Commit Graph

720 Commits

Author SHA1 Message Date
Linus Torvalds
54450af662 parisc architecture fixes and updates for kernel v6.12-rc1:
- Convert parisc to the generic clockevents framework
 - Fix syscall and mm for 64-bit userspace
 - Fix stack start when ADDR_NO_RANDOMIZE personality is set
 - Fix mmap(MAP_STACK) to map upward growing expandable memory on parisc
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Merge tag 'parisc-for-6.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux

Pull parisc architecture updates from Helge Deller:

 - On parisc we now use the generic clockevent framework for timekeeping

 - Although there is no 64-bit glibc/userspace for parisc yet, for
   testing purposes one can run statically linked 64-bit binaries. This
   patchset contains two patches which fix 64-bit userspace which has
   been broken since kernel 4.19

 - Fix the userspace stack position and size when the ADDR_NO_RANDOMIZE
   personality is enabled

 - On other architectures mmap(MAP_GROWSDOWN | MAP_STACK) creates a
   downward-growing stack. On parisc mmap(MAP_STACK) is now sufficient
   to create an upward-growing stack

* tag 'parisc-for-6.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
  parisc: Allow mmap(MAP_STACK) memory to automatically expand upwards
  parisc: Use PRIV_USER instead of hardcoded value
  parisc: Fix itlb miss handler for 64-bit programs
  parisc: Fix 64-bit userspace syscall path
  parisc: Fix stack start for ADDR_NO_RANDOMIZE personality
  parisc: Convert to generic clockevents
  parisc: pdc_stable: Constify struct kobj_type
2024-09-19 07:43:13 +02:00
Helge Deller
f31b256994 parisc: Fix stack start for ADDR_NO_RANDOMIZE personality
Fix the stack start address calculation for the parisc architecture in
setup_arg_pages() when address randomization is disabled. When the
ADDR_NO_RANDOMIZE process personality is disabled there is no need to add
additional space for the stack.
Note that this patch touches code inside an #ifdef CONFIG_STACK_GROWSUP hunk,
which is why only the parisc architecture is affected since it's the
only Linux architecture where the stack grows upwards.

Without this patch you will find the stack in the middle of some
mapped libaries and suddenly limited to 6MB instead of 8MB:

root@parisc:~# setarch -R /bin/bash -c "cat /proc/self/maps"
00010000-00019000 r-xp 00000000 08:05 1182034           /usr/bin/cat
00019000-0001a000 rwxp 00009000 08:05 1182034           /usr/bin/cat
0001a000-0003b000 rwxp 00000000 00:00 0                 [heap]
f90c4000-f9283000 r-xp 00000000 08:05 1573004           /usr/lib/hppa-linux-gnu/libc.so.6
f9283000-f9285000 r--p 001bf000 08:05 1573004           /usr/lib/hppa-linux-gnu/libc.so.6
f9285000-f928a000 rwxp 001c1000 08:05 1573004           /usr/lib/hppa-linux-gnu/libc.so.6
f928a000-f9294000 rwxp 00000000 00:00 0
f9301000-f9323000 rwxp 00000000 00:00 0                 [stack]
f98b4000-f98e4000 r-xp 00000000 08:05 1572869           /usr/lib/hppa-linux-gnu/ld.so.1
f98e4000-f98e5000 r--p 00030000 08:05 1572869           /usr/lib/hppa-linux-gnu/ld.so.1
f98e5000-f98e9000 rwxp 00031000 08:05 1572869           /usr/lib/hppa-linux-gnu/ld.so.1
f9ad8000-f9b00000 rw-p 00000000 00:00 0
f9b00000-f9b01000 r-xp 00000000 00:00 0                 [vdso]

With the patch the stack gets correctly mapped at the end
of the process memory map:

root@panama:~# setarch -R /bin/bash -c "cat /proc/self/maps"
00010000-00019000 r-xp 00000000 08:13 16385582          /usr/bin/cat
00019000-0001a000 rwxp 00009000 08:13 16385582          /usr/bin/cat
0001a000-0003b000 rwxp 00000000 00:00 0                 [heap]
fef29000-ff0eb000 r-xp 00000000 08:13 16122400          /usr/lib/hppa-linux-gnu/libc.so.6
ff0eb000-ff0ed000 r--p 001c2000 08:13 16122400          /usr/lib/hppa-linux-gnu/libc.so.6
ff0ed000-ff0f2000 rwxp 001c4000 08:13 16122400          /usr/lib/hppa-linux-gnu/libc.so.6
ff0f2000-ff0fc000 rwxp 00000000 00:00 0
ff4b4000-ff4e4000 r-xp 00000000 08:13 16121913          /usr/lib/hppa-linux-gnu/ld.so.1
ff4e4000-ff4e6000 r--p 00030000 08:13 16121913          /usr/lib/hppa-linux-gnu/ld.so.1
ff4e6000-ff4ea000 rwxp 00032000 08:13 16121913          /usr/lib/hppa-linux-gnu/ld.so.1
ff6d7000-ff6ff000 rw-p 00000000 00:00 0
ff6ff000-ff700000 r-xp 00000000 00:00 0                 [vdso]
ff700000-ff722000 rwxp 00000000 00:00 0                 [stack]

Reported-by: Camm Maguire <camm@maguirefamily.org>
Signed-off-by: Helge Deller <deller@gmx.de>
Fixes: d045c77c1a ("parisc,metag: Fix crashes due to stack randomization on stack-grows-upwards architectures")
Fixes: 17d9822d4b ("parisc: Consider stack randomization for mmap base only when necessary")
Cc: stable@vger.kernel.org	# v5.2+
2024-09-09 08:53:17 +02:00
Mateusz Guzik
0d196e7589 exec: don't WARN for racy path_noexec check
Both i_mode and noexec checks wrapped in WARN_ON stem from an artifact
of the previous implementation. They used to legitimately check for the
condition, but that got moved up in two commits:
633fb6ac39 ("exec: move S_ISREG() check earlier")
0fd338b2d2 ("exec: move path_noexec() check earlier")

Instead of being removed said checks are WARN_ON'ed instead, which
has some debug value.

However, the spurious path_noexec check is racy, resulting in
unwarranted warnings should someone race with setting the noexec flag.

One can note there is more to perm-checking whether execve is allowed
and none of the conditions are guaranteed to still hold after they were
tested for.

Additionally this does not validate whether the code path did any perm
checking to begin with -- it will pass if the inode happens to be
regular.

Keep the redundant path_noexec() check even though it's mindless
nonsense checking for guarantee that isn't given so drop the WARN.

Reword the commentary and do small tidy ups while here.

Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20240805131721.765484-1-mjguzik@gmail.com
[brauner: keep redundant path_noexec() check]
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-08-30 08:22:33 +02:00
Kees Cook
f50733b45d exec: Fix ToCToU between perm check and set-uid/gid usage
When opening a file for exec via do_filp_open(), permission checking is
done against the file's metadata at that moment, and on success, a file
pointer is passed back. Much later in the execve() code path, the file
metadata (specifically mode, uid, and gid) is used to determine if/how
to set the uid and gid. However, those values may have changed since the
permissions check, meaning the execution may gain unintended privileges.

For example, if a file could change permissions from executable and not
set-id:

---------x 1 root root 16048 Aug  7 13:16 target

to set-id and non-executable:

---S------ 1 root root 16048 Aug  7 13:16 target

it is possible to gain root privileges when execution should have been
disallowed.

While this race condition is rare in real-world scenarios, it has been
observed (and proven exploitable) when package managers are updating
the setuid bits of installed programs. Such files start with being
world-executable but then are adjusted to be group-exec with a set-uid
bit. For example, "chmod o-x,u+s target" makes "target" executable only
by uid "root" and gid "cdrom", while also becoming setuid-root:

-rwxr-xr-x 1 root cdrom 16048 Aug  7 13:16 target

becomes:

-rwsr-xr-- 1 root cdrom 16048 Aug  7 13:16 target

But racing the chmod means users without group "cdrom" membership can
get the permission to execute "target" just before the chmod, and when
the chmod finishes, the exec reaches brpm_fill_uid(), and performs the
setuid to root, violating the expressed authorization of "only cdrom
group members can setuid to root".

Re-check that we still have execute permissions in case the metadata
has changed. It would be better to keep a copy from the perm-check time,
but until we can do that refactoring, the least-bad option is to do a
full inode_permission() call (under inode lock). It is understood that
this is safe against dead-locks, but hardly optimal.

Reported-by: Marco Vanotti <mvanotti@google.com>
Tested-by: Marco Vanotti <mvanotti@google.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: stable@vger.kernel.org
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Signed-off-by: Kees Cook <kees@kernel.org>
2024-08-13 13:24:29 -07:00
Joel Granados
78eb4ea25c sysctl: treewide: constify the ctl_table argument of proc_handlers
const qualify the struct ctl_table argument in the proc_handler function
signatures. This is a prerequisite to moving the static ctl_table
structs into .rodata data which will ensure that proc_handler function
pointers cannot be modified.

This patch has been generated by the following coccinelle script:

```
  virtual patch

  @r1@
  identifier ctl, write, buffer, lenp, ppos;
  identifier func !~ "appldata_(timer|interval)_handler|sched_(rt|rr)_handler|rds_tcp_skbuf_handler|proc_sctp_do_(hmac_alg|rto_min|rto_max|udp_port|alpha_beta|auth|probe_interval)";
  @@

  int func(
  - struct ctl_table *ctl
  + const struct ctl_table *ctl
    ,int write, void *buffer, size_t *lenp, loff_t *ppos);

  @r2@
  identifier func, ctl, write, buffer, lenp, ppos;
  @@

  int func(
  - struct ctl_table *ctl
  + const struct ctl_table *ctl
    ,int write, void *buffer, size_t *lenp, loff_t *ppos)
  { ... }

  @r3@
  identifier func;
  @@

  int func(
  - struct ctl_table *
  + const struct ctl_table *
    ,int , void *, size_t *, loff_t *);

  @r4@
  identifier func, ctl;
  @@

  int func(
  - struct ctl_table *ctl
  + const struct ctl_table *ctl
    ,int , void *, size_t *, loff_t *);

  @r5@
  identifier func, write, buffer, lenp, ppos;
  @@

  int func(
  - struct ctl_table *
  + const struct ctl_table *
    ,int write, void *buffer, size_t *lenp, loff_t *ppos);

```

* Code formatting was adjusted in xfs_sysctl.c to comply with code
  conventions. The xfs_stats_clear_proc_handler,
  xfs_panic_mask_proc_handler and xfs_deprecated_dointvec_minmax where
  adjusted.

* The ctl_table argument in proc_watchdog_common was const qualified.
  This is called from a proc_handler itself and is calling back into
  another proc_handler, making it necessary to change it as part of the
  proc_handler migration.

Co-developed-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Co-developed-by: Joel Granados <j.granados@samsung.com>
Signed-off-by: Joel Granados <j.granados@samsung.com>
2024-07-24 20:59:29 +02:00
Linus Torvalds
e9e969797b execve fix for v6.11-rc1
- Move KUnit tests to tests/ subdirectory
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Merge tag 'execve-v6.11-rc1-fix1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull execve fix from Kees Cook:
 "This moves the exec and binfmt_elf tests out of your way and into the
  tests/ subdirectory, following the newly ratified KUnit naming
  conventions. :)"

* tag 'execve-v6.11-rc1-fix1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  execve: Move KUnit tests to tests/ subdirectory
2024-07-23 17:30:42 -07:00
Kees Cook
b6f5ee4d53 execve: Move KUnit tests to tests/ subdirectory
Move the exec KUnit tests into a separate directory to avoid polluting
the local directory namespace. Additionally update MAINTAINERS for the
new files.

Reviewed-by: David Gow <davidgow@google.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Acked-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20240720170310.it.942-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
2024-07-22 18:25:47 -07:00
Linus Torvalds
72fda6c8e5 execve updates for v6.11-rc1
- Use value of kernel.randomize_va_space once per exec (Alexey Dobriyan)
 
 - Honor PT_LOAD alignment for static PIE
 
 - Make bprm->argmin only visible under CONFIG_MMU
 
 - Add KUnit testing of bprm_stack_limits()
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Merge tag 'execve-v6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull execve updates from Kees Cook:

 - Use value of kernel.randomize_va_space once per exec (Alexey
   Dobriyan)

 - Honor PT_LOAD alignment for static PIE

 - Make bprm->argmin only visible under CONFIG_MMU

 - Add KUnit testing of bprm_stack_limits()

* tag 'execve-v6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  exec: Avoid pathological argc, envc, and bprm->p values
  execve: Keep bprm->argmin behind CONFIG_MMU
  ELF: fix kernel.randomize_va_space double read
  exec: Add KUnit test for bprm_stack_limits()
  binfmt_elf: Honor PT_LOAD alignment for static PIE
  binfmt_elf: Calculate total_size earlier
  selftests/exec: Build both static and non-static load_address tests
2024-07-16 12:59:20 -07:00
Kees Cook
21f9310830 exec: Avoid pathological argc, envc, and bprm->p values
Make sure nothing goes wrong with the string counters or the bprm's
belief about the stack pointer. Add checks and matching self-tests.

Take special care for !CONFIG_MMU, since argmin is not exposed there.

For 32-bit validation, 32-bit UML was used:
$ tools/testing/kunit/kunit.py run \
	--make_options CROSS_COMPILE=i686-linux-gnu- \
	--make_options SUBARCH=i386 \
	exec

For !MMU validation, m68k was used:
$ tools/testing/kunit/kunit.py run \
	--arch m68k --make_option CROSS_COMPILE=m68k-linux-gnu- \
	exec

Link: https://lore.kernel.org/r/20240520021615.741800-2-keescook@chromium.org
Link: https://lore.kernel.org/r/20240621205046.4001362-2-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
2024-07-13 21:31:58 -07:00
Kees Cook
084ebf7ca8 execve: Keep bprm->argmin behind CONFIG_MMU
When argmin was added in commit 655c16a8ce ("exec: separate
MM_ANONPAGES and RLIMIT_STACK accounting"), it was intended only for
validating stack limits on CONFIG_MMU[1]. All checking for reaching the
limit (argmin) is wrapped in CONFIG_MMU ifdef checks, though setting
argmin was not. That argmin is only supposed to be used under CONFIG_MMU
was rediscovered recently[2], and I don't want to trip over this again.

Move argmin's declaration into the existing CONFIG_MMU area, and add
helpers functions so the MMU tests can be consolidated.

Link: https://lore.kernel.org/all/20181126122307.GA1660@redhat.com [1]
Link: https://lore.kernel.org/all/202406211253.7037F69@keescook/ [2]
Link: https://lore.kernel.org/r/20240621205046.4001362-1-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
2024-07-13 21:31:57 -07:00
Kees Cook
60371f43e5 exec: Add KUnit test for bprm_stack_limits()
Since bprm_stack_limits() operates with very limited side-effects, add
it as the first exec.c KUnit test. Add to Kconfig and adjust MAINTAINERS
file to include it.

Tested on 64-bit UML:
$ tools/testing/kunit/kunit.py run exec

Link: https://lore.kernel.org/lkml/20240520021615.741800-1-keescook@chromium.org/
Signed-off-by: Kees Cook <kees@kernel.org>
2024-06-19 13:13:55 -07:00
Christian Brauner
2a010c4128 fs: don't block i_writecount during exec
Back in 2021 we already discussed removing deny_write_access() for
executables. Back then I was hesistant because I thought that this might
cause issues in userspace. But even back then I had started taking some
notes on what could potentially depend on this and I didn't come up with
a lot so I've changed my mind and I would like to try this.

Here are some of the notes that I took:

(1) The deny_write_access() mechanism is causing really pointless issues
    such as [1]. If a thread in a thread-group opens a file writable,
    then writes some stuff, then closing the file descriptor and then
    calling execve() they can fail the execve() with ETXTBUSY because
    another thread in the thread-group could have concurrently called
    fork(). Multi-threaded libraries such as go suffer from this.

(2) There are userspace attacks that rely on overwriting the binary of a
    running process. These attacks are _mitigated_ but _not at all
    prevented_ from ocurring by the deny_write_access() mechanism.

    I'll go over some details. The clearest example of such attacks was
    the attack against runC in CVE-2019-5736 (cf. [3]).

    An attack could compromise the runC host binary from inside a
    _privileged_ runC container. The malicious binary could then be used
    to take over the host.

    (It is crucial to note that this attack is _not_ possible with
     unprivileged containers. IOW, the setup here is already insecure.)

    The attack can be made when attaching to a running container or when
    starting a container running a specially crafted image. For example,
    when runC attaches to a container the attacker can trick it into
    executing itself.

    This could be done by replacing the target binary inside the
    container with a custom binary pointing back at the runC binary
    itself. As an example, if the target binary was /bin/bash, this
    could be replaced with an executable script specifying the
    interpreter path #!/proc/self/exe.

    As such when /bin/bash is executed inside the container, instead the
    target of /proc/self/exe will be executed. That magic link will
    point to the runc binary on the host. The attacker can then proceed
    to write to the target of /proc/self/exe to try and overwrite the
    runC binary on the host.

    However, this will not succeed because of deny_write_access(). Now,
    one might think that this would prevent the attack but it doesn't.

    To overcome this, the attacker has multiple ways:
    * Open a file descriptor to /proc/self/exe using the O_PATH flag and
      then proceed to reopen the binary as O_WRONLY through
      /proc/self/fd/<nr> and try to write to it in a busy loop from a
      separate process. Ultimately it will succeed when the runC binary
      exits. After this the runC binary is compromised and can be used
      to attack other containers or the host itself.
    * Use a malicious shared library annotating a function in there with
      the constructor attribute making the malicious function run as an
      initializor. The malicious library will then open /proc/self/exe
      for creating a new entry under /proc/self/fd/<nr>. It'll then call
      exec to a) force runC to exit and b) hand the file descriptor off
      to a program that then reopens /proc/self/fd/<nr> for writing
      (which is now possible because runC has exited) and overwriting
      that binary.

    To sum up: the deny_write_access() mechanism doesn't prevent such
    attacks in insecure setups. It just makes them minimally harder.
    That's all.

    The only way back then to prevent this is to create a temporary copy
    of the calling binary itself when it starts or attaches to
    containers. So what I did back then for LXC (and Aleksa for runC)
    was to create an anonymous, in-memory file using the memfd_create()
    system call and to copy itself into the temporary in-memory file,
    which is then sealed to prevent further modifications. This sealed,
    in-memory file copy is then executed instead of the original on-disk
    binary.

    Any compromising write operations from a privileged container to the
    host binary will then write to the temporary in-memory binary and
    not to the host binary on-disk, preserving the integrity of the host
    binary. Also as the temporary, in-memory binary is sealed, writes to
    this will also fail.

    The point is that deny_write_access() is uselss to prevent these
    attacks.

(3) Denying write access to an inode because it's currently used in an
    exec path could easily be done on an LSM level. It might need an
    additional hook but that should be about it.

(4) The MAP_DENYWRITE flag for mmap() has been deprecated a long time
    ago so while we do protect the main executable the bigger portion of
    the things you'd think need protecting such as the shared libraries
    aren't. IOW, we let anyone happily overwrite shared libraries.

(5) We removed all remaining uses of VM_DENYWRITE in [2]. That means:
    (5.1) We removed the legacy uselib() protection for preventing
          overwriting of shared libraries. Nobody cared in 3 years.
    (5.2) We allow write access to the elf interpreter after exec
          completed treating it on a par with shared libraries.

Yes, someone in userspace could potentially be relying on this. It's not
completely out of the realm of possibility but let's find out if that's
actually the case and not guess.

Link: https://github.com/golang/go/issues/22315 [1]
Link: 49624efa65 ("Merge tag 'denywrite-for-5.15' of git://github.com/davidhildenbrand/linux") [2]
Link: https://unit42.paloaltonetworks.com/breaking-docker-via-runc-explaining-cve-2019-5736 [3]
Link: https://lwn.net/Articles/866493
Link: https://github.com/golang/go/issues/22220
Link: 5bf8c0cf09/src/cmd/go/internal/work/buildid.go (L724)
Link: 5bf8c0cf09/src/cmd/go/internal/work/exec.go (L1493)
Link: 5bf8c0cf09/src/cmd/go/internal/script/cmds.go (L457)
Link: 5bf8c0cf09/src/cmd/go/internal/test/test.go (L1557)
Link: 5bf8c0cf09/src/os/exec/lp_linux_test.go (L61)
Link: https://github.com/buildkite/agent/pull/2736
Link: https://github.com/rust-lang/rust/issues/114554
Link: https://bugs.openjdk.org/browse/JDK-8068370
Link: https://github.com/dotnet/runtime/issues/58964
Link: https://lore.kernel.org/r/20240531-vfs-i_writecount-v1-1-a17bea7ee36b@kernel.org
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-06-03 15:52:10 +02:00
Linus Torvalds
61307b7be4 The usual shower of singleton fixes and minor series all over MM,
documented (hopefully adequately) in the respective changelogs.  Notable
 series include:
 
 - Lucas Stach has provided some page-mapping
   cleanup/consolidation/maintainability work in the series "mm/treewide:
   Remove pXd_huge() API".
 
 - In the series "Allow migrate on protnone reference with
   MPOL_PREFERRED_MANY policy", Donet Tom has optimized mempolicy's
   MPOL_PREFERRED_MANY mode, yielding almost doubled performance in one
   test.
 
 - In their series "Memory allocation profiling" Kent Overstreet and
   Suren Baghdasaryan have contributed a means of determining (via
   /proc/allocinfo) whereabouts in the kernel memory is being allocated:
   number of calls and amount of memory.
 
 - Matthew Wilcox has provided the series "Various significant MM
   patches" which does a number of rather unrelated things, but in largely
   similar code sites.
 
 - In his series "mm: page_alloc: freelist migratetype hygiene" Johannes
   Weiner has fixed the page allocator's handling of migratetype requests,
   with resulting improvements in compaction efficiency.
 
 - In the series "make the hugetlb migration strategy consistent" Baolin
   Wang has fixed a hugetlb migration issue, which should improve hugetlb
   allocation reliability.
 
 - Liu Shixin has hit an I/O meltdown caused by readahead in a
   memory-tight memcg.  Addressed in the series "Fix I/O high when memory
   almost met memcg limit".
 
 - In the series "mm/filemap: optimize folio adding and splitting" Kairui
   Song has optimized pagecache insertion, yielding ~10% performance
   improvement in one test.
 
 - Baoquan He has cleaned up and consolidated the early zone
   initialization code in the series "mm/mm_init.c: refactor
   free_area_init_core()".
 
 - Baoquan has also redone some MM initializatio code in the series
   "mm/init: minor clean up and improvement".
 
 - MM helper cleanups from Christoph Hellwig in his series "remove
   follow_pfn".
 
 - More cleanups from Matthew Wilcox in the series "Various page->flags
   cleanups".
 
 - Vlastimil Babka has contributed maintainability improvements in the
   series "memcg_kmem hooks refactoring".
 
 - More folio conversions and cleanups in Matthew Wilcox's series
 
 	"Convert huge_zero_page to huge_zero_folio"
 	"khugepaged folio conversions"
 	"Remove page_idle and page_young wrappers"
 	"Use folio APIs in procfs"
 	"Clean up __folio_put()"
 	"Some cleanups for memory-failure"
 	"Remove page_mapping()"
 	"More folio compat code removal"
 
 - David Hildenbrand chipped in with "fs/proc/task_mmu: convert hugetlb
   functions to work on folis".
 
 - Code consolidation and cleanup work related to GUP's handling of
   hugetlbs in Peter Xu's series "mm/gup: Unify hugetlb, part 2".
 
 - Rick Edgecombe has developed some fixes to stack guard gaps in the
   series "Cover a guard gap corner case".
 
 - Jinjiang Tu has fixed KSM's behaviour after a fork+exec in the series
   "mm/ksm: fix ksm exec support for prctl".
 
 - Baolin Wang has implemented NUMA balancing for multi-size THPs.  This
   is a simple first-cut implementation for now.  The series is "support
   multi-size THP numa balancing".
 
 - Cleanups to vma handling helper functions from Matthew Wilcox in the
   series "Unify vma_address and vma_pgoff_address".
 
 - Some selftests maintenance work from Dev Jain in the series
   "selftests/mm: mremap_test: Optimizations and style fixes".
 
 - Improvements to the swapping of multi-size THPs from Ryan Roberts in
   the series "Swap-out mTHP without splitting".
 
 - Kefeng Wang has significantly optimized the handling of arm64's
   permission page faults in the series
 
 	"arch/mm/fault: accelerate pagefault when badaccess"
 	"mm: remove arch's private VM_FAULT_BADMAP/BADACCESS"
 
 - GUP cleanups from David Hildenbrand in "mm/gup: consistently call it
   GUP-fast".
 
 - hugetlb fault code cleanups from Vishal Moola in "Hugetlb fault path to
   use struct vm_fault".
 
 - selftests build fixes from John Hubbard in the series "Fix
   selftests/mm build without requiring "make headers"".
 
 - Memory tiering fixes/improvements from Ho-Ren (Jack) Chuang in the
   series "Improved Memory Tier Creation for CPUless NUMA Nodes".  Fixes
   the initialization code so that migration between different memory types
   works as intended.
 
 - David Hildenbrand has improved follow_pte() and fixed an errant driver
   in the series "mm: follow_pte() improvements and acrn follow_pte()
   fixes".
 
 - David also did some cleanup work on large folio mapcounts in his
   series "mm: mapcount for large folios + page_mapcount() cleanups".
 
 - Folio conversions in KSM in Alex Shi's series "transfer page to folio
   in KSM".
 
 - Barry Song has added some sysfs stats for monitoring multi-size THP's
   in the series "mm: add per-order mTHP alloc and swpout counters".
 
 - Some zswap cleanups from Yosry Ahmed in the series "zswap same-filled
   and limit checking cleanups".
 
 - Matthew Wilcox has been looking at buffer_head code and found the
   documentation to be lacking.  The series is "Improve buffer head
   documentation".
 
 - Multi-size THPs get more work, this time from Lance Yang.  His series
   "mm/madvise: enhance lazyfreeing with mTHP in madvise_free" optimizes
   the freeing of these things.
 
 - Kemeng Shi has added more userspace-visible writeback instrumentation
   in the series "Improve visibility of writeback".
 
 - Kemeng Shi then sent some maintenance work on top in the series "Fix
   and cleanups to page-writeback".
 
 - Matthew Wilcox reduces mmap_lock traffic in the anon vma code in the
   series "Improve anon_vma scalability for anon VMAs".  Intel's test bot
   reported an improbable 3x improvement in one test.
 
 - SeongJae Park adds some DAMON feature work in the series
 
 	"mm/damon: add a DAMOS filter type for page granularity access recheck"
 	"selftests/damon: add DAMOS quota goal test"
 
 - Also some maintenance work in the series
 
 	"mm/damon/paddr: simplify page level access re-check for pageout"
 	"mm/damon: misc fixes and improvements"
 
 - David Hildenbrand has disabled some known-to-fail selftests ni the
   series "selftests: mm: cow: flag vmsplice() hugetlb tests as XFAIL".
 
 - memcg metadata storage optimizations from Shakeel Butt in "memcg:
   reduce memory consumption by memcg stats".
 
 - DAX fixes and maintenance work from Vishal Verma in the series
   "dax/bus.c: Fixups for dax-bus locking".
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Merge tag 'mm-stable-2024-05-17-19-19' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull mm updates from Andrew Morton:
 "The usual shower of singleton fixes and minor series all over MM,
  documented (hopefully adequately) in the respective changelogs.
  Notable series include:

   - Lucas Stach has provided some page-mapping cleanup/consolidation/
     maintainability work in the series "mm/treewide: Remove pXd_huge()
     API".

   - In the series "Allow migrate on protnone reference with
     MPOL_PREFERRED_MANY policy", Donet Tom has optimized mempolicy's
     MPOL_PREFERRED_MANY mode, yielding almost doubled performance in
     one test.

   - In their series "Memory allocation profiling" Kent Overstreet and
     Suren Baghdasaryan have contributed a means of determining (via
     /proc/allocinfo) whereabouts in the kernel memory is being
     allocated: number of calls and amount of memory.

   - Matthew Wilcox has provided the series "Various significant MM
     patches" which does a number of rather unrelated things, but in
     largely similar code sites.

   - In his series "mm: page_alloc: freelist migratetype hygiene"
     Johannes Weiner has fixed the page allocator's handling of
     migratetype requests, with resulting improvements in compaction
     efficiency.

   - In the series "make the hugetlb migration strategy consistent"
     Baolin Wang has fixed a hugetlb migration issue, which should
     improve hugetlb allocation reliability.

   - Liu Shixin has hit an I/O meltdown caused by readahead in a
     memory-tight memcg. Addressed in the series "Fix I/O high when
     memory almost met memcg limit".

   - In the series "mm/filemap: optimize folio adding and splitting"
     Kairui Song has optimized pagecache insertion, yielding ~10%
     performance improvement in one test.

   - Baoquan He has cleaned up and consolidated the early zone
     initialization code in the series "mm/mm_init.c: refactor
     free_area_init_core()".

   - Baoquan has also redone some MM initializatio code in the series
     "mm/init: minor clean up and improvement".

   - MM helper cleanups from Christoph Hellwig in his series "remove
     follow_pfn".

   - More cleanups from Matthew Wilcox in the series "Various
     page->flags cleanups".

   - Vlastimil Babka has contributed maintainability improvements in the
     series "memcg_kmem hooks refactoring".

   - More folio conversions and cleanups in Matthew Wilcox's series:
	"Convert huge_zero_page to huge_zero_folio"
	"khugepaged folio conversions"
	"Remove page_idle and page_young wrappers"
	"Use folio APIs in procfs"
	"Clean up __folio_put()"
	"Some cleanups for memory-failure"
	"Remove page_mapping()"
	"More folio compat code removal"

   - David Hildenbrand chipped in with "fs/proc/task_mmu: convert
     hugetlb functions to work on folis".

   - Code consolidation and cleanup work related to GUP's handling of
     hugetlbs in Peter Xu's series "mm/gup: Unify hugetlb, part 2".

   - Rick Edgecombe has developed some fixes to stack guard gaps in the
     series "Cover a guard gap corner case".

   - Jinjiang Tu has fixed KSM's behaviour after a fork+exec in the
     series "mm/ksm: fix ksm exec support for prctl".

   - Baolin Wang has implemented NUMA balancing for multi-size THPs.
     This is a simple first-cut implementation for now. The series is
     "support multi-size THP numa balancing".

   - Cleanups to vma handling helper functions from Matthew Wilcox in
     the series "Unify vma_address and vma_pgoff_address".

   - Some selftests maintenance work from Dev Jain in the series
     "selftests/mm: mremap_test: Optimizations and style fixes".

   - Improvements to the swapping of multi-size THPs from Ryan Roberts
     in the series "Swap-out mTHP without splitting".

   - Kefeng Wang has significantly optimized the handling of arm64's
     permission page faults in the series
	"arch/mm/fault: accelerate pagefault when badaccess"
	"mm: remove arch's private VM_FAULT_BADMAP/BADACCESS"

   - GUP cleanups from David Hildenbrand in "mm/gup: consistently call
     it GUP-fast".

   - hugetlb fault code cleanups from Vishal Moola in "Hugetlb fault
     path to use struct vm_fault".

   - selftests build fixes from John Hubbard in the series "Fix
     selftests/mm build without requiring "make headers"".

   - Memory tiering fixes/improvements from Ho-Ren (Jack) Chuang in the
     series "Improved Memory Tier Creation for CPUless NUMA Nodes".
     Fixes the initialization code so that migration between different
     memory types works as intended.

   - David Hildenbrand has improved follow_pte() and fixed an errant
     driver in the series "mm: follow_pte() improvements and acrn
     follow_pte() fixes".

   - David also did some cleanup work on large folio mapcounts in his
     series "mm: mapcount for large folios + page_mapcount() cleanups".

   - Folio conversions in KSM in Alex Shi's series "transfer page to
     folio in KSM".

   - Barry Song has added some sysfs stats for monitoring multi-size
     THP's in the series "mm: add per-order mTHP alloc and swpout
     counters".

   - Some zswap cleanups from Yosry Ahmed in the series "zswap
     same-filled and limit checking cleanups".

   - Matthew Wilcox has been looking at buffer_head code and found the
     documentation to be lacking. The series is "Improve buffer head
     documentation".

   - Multi-size THPs get more work, this time from Lance Yang. His
     series "mm/madvise: enhance lazyfreeing with mTHP in madvise_free"
     optimizes the freeing of these things.

   - Kemeng Shi has added more userspace-visible writeback
     instrumentation in the series "Improve visibility of writeback".

   - Kemeng Shi then sent some maintenance work on top in the series
     "Fix and cleanups to page-writeback".

   - Matthew Wilcox reduces mmap_lock traffic in the anon vma code in
     the series "Improve anon_vma scalability for anon VMAs". Intel's
     test bot reported an improbable 3x improvement in one test.

   - SeongJae Park adds some DAMON feature work in the series
	"mm/damon: add a DAMOS filter type for page granularity access recheck"
	"selftests/damon: add DAMOS quota goal test"

   - Also some maintenance work in the series
	"mm/damon/paddr: simplify page level access re-check for pageout"
	"mm/damon: misc fixes and improvements"

   - David Hildenbrand has disabled some known-to-fail selftests ni the
     series "selftests: mm: cow: flag vmsplice() hugetlb tests as
     XFAIL".

   - memcg metadata storage optimizations from Shakeel Butt in "memcg:
     reduce memory consumption by memcg stats".

   - DAX fixes and maintenance work from Vishal Verma in the series
     "dax/bus.c: Fixups for dax-bus locking""

* tag 'mm-stable-2024-05-17-19-19' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (426 commits)
  memcg, oom: cleanup unused memcg_oom_gfp_mask and memcg_oom_order
  selftests/mm: hugetlb_madv_vs_map: avoid test skipping by querying hugepage size at runtime
  mm/hugetlb: add missing VM_FAULT_SET_HINDEX in hugetlb_wp
  mm/hugetlb: add missing VM_FAULT_SET_HINDEX in hugetlb_fault
  selftests: cgroup: add tests to verify the zswap writeback path
  mm: memcg: make alloc_mem_cgroup_per_node_info() return bool
  mm/damon/core: fix return value from damos_wmark_metric_value
  mm: do not update memcg stats for NR_{FILE/SHMEM}_PMDMAPPED
  selftests: cgroup: remove redundant enabling of memory controller
  Docs/mm/damon/maintainer-profile: allow posting patches based on damon/next tree
  Docs/mm/damon/maintainer-profile: change the maintainer's timezone from PST to PT
  Docs/mm/damon/design: use a list for supported filters
  Docs/admin-guide/mm/damon/usage: fix wrong schemes effective quota update command
  Docs/admin-guide/mm/damon/usage: fix wrong example of DAMOS filter matching sysfs file
  selftests/damon: classify tests for functionalities and regressions
  selftests/damon/_damon_sysfs: use 'is' instead of '==' for 'None'
  selftests/damon/_damon_sysfs: find sysfs mount point from /proc/mounts
  selftests/damon/_damon_sysfs: check errors from nr_schemes file reads
  mm/damon/core: initialize ->esz_bp from damos_quota_init_priv()
  selftests/damon: add a test for DAMOS quota goal
  ...
2024-05-19 09:21:03 -07:00
Jinjiang Tu
3a9e567ca4 mm/ksm: fix ksm exec support for prctl
Patch series "mm/ksm: fix ksm exec support for prctl", v4.

commit 3c6f33b727 ("mm/ksm: support fork/exec for prctl") inherits
MMF_VM_MERGE_ANY flag when a task calls execve().  However, it doesn't
create the mm_slot, so ksmd will not try to scan this task.  The first
patch fixes the issue.

The second patch refactors to prepare for the third patch.  The third
patch extends the selftests of ksm to verfity the deduplication really
happens after fork/exec inherits ths KSM setting.


This patch (of 3):

commit 3c6f33b727 ("mm/ksm: support fork/exec for prctl") inherits
MMF_VM_MERGE_ANY flag when a task calls execve().  Howerver, it doesn't
create the mm_slot, so ksmd will not try to scan this task.

To fix it, allocate and add the mm_slot to ksm_mm_head in __bprm_mm_init()
when the mm has MMF_VM_MERGE_ANY flag.

Link: https://lkml.kernel.org/r/20240328111010.1502191-1-tujinjiang@huawei.com
Link: https://lkml.kernel.org/r/20240328111010.1502191-2-tujinjiang@huawei.com
Fixes: 3c6f33b727 ("mm/ksm: support fork/exec for prctl")
Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Nanyong Sun <sunnanyong@huawei.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Stefan Roesch <shr@devkernel.io>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-04-25 20:56:29 -07:00
Marco Elver
c82389947d tracing: Add sched_prepare_exec tracepoint
Add "sched_prepare_exec" tracepoint, which is run right after the point
of no return but before the current task assumes its new exec identity.

Unlike the tracepoint "sched_process_exec", the "sched_prepare_exec"
tracepoint runs before flushing the old exec, i.e. while the task still
has the original state (such as original MM), but when the new exec
either succeeds or crashes (but never returns to the original exec).

Being able to trace this event can be helpful in a number of use cases:

  * allowing tracing eBPF programs access to the original MM on exec,
    before current->mm is replaced;
  * counting exec in the original task (via perf event);
  * profiling flush time ("sched_prepare_exec" to "sched_process_exec").

Example of tracing output:

 $ cat /sys/kernel/debug/tracing/trace_pipe
    <...>-379  [003] .....  179.626921: sched_prepare_exec: interp=/usr/bin/sshd filename=/usr/bin/sshd pid=379 comm=sshd
    <...>-381  [002] .....  180.048580: sched_prepare_exec: interp=/bin/bash filename=/bin/bash pid=381 comm=sshd
    <...>-385  [001] .....  180.068277: sched_prepare_exec: interp=/usr/bin/tty filename=/usr/bin/tty pid=385 comm=bash
    <...>-389  [006] .....  192.020147: sched_prepare_exec: interp=/usr/bin/dmesg filename=/usr/bin/dmesg pid=389 comm=bash

Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20240411102158.1272267-1-elver@google.com
Signed-off-by: Kees Cook <keescook@chromium.org>
2024-04-11 09:02:21 -07:00
Linus Torvalds
f4a432914a execve fixes for v6.9-rc2
- Fix selftests to conform to the TAP output format (Muhammad Usama Anjum)
 
 - Fix NOMMU linux_binprm::exec pointer in auxv (Max Filippov)
 
 - Replace deprecated strncpy usage (Justin Stitt)
 
 - Replace another /bin/sh instance in selftests
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Merge tag 'execve-v6.9-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull execve fixes from Kees Cook:

 - Fix selftests to conform to the TAP output format (Muhammad Usama
   Anjum)

 - Fix NOMMU linux_binprm::exec pointer in auxv (Max Filippov)

 - Replace deprecated strncpy usage (Justin Stitt)

 - Replace another /bin/sh instance in selftests

* tag 'execve-v6.9-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  binfmt: replace deprecated strncpy
  exec: Fix NOMMU linux_binprm::exec in transfer_args_to_stack()
  selftests/exec: Convert remaining /bin/sh to /bin/bash
  selftests/exec: execveat: Improve debug reporting
  selftests/exec: recursion-depth: conform test to TAP format output
  selftests/exec: load_address: conform test to TAP format output
  selftests/exec: binfmt_script: Add the overall result line according to TAP
2024-03-27 09:57:30 -07:00
Max Filippov
2aea94ac14 exec: Fix NOMMU linux_binprm::exec in transfer_args_to_stack()
In NOMMU kernel the value of linux_binprm::p is the offset inside the
temporary program arguments array maintained in separate pages in the
linux_binprm::page. linux_binprm::exec being a copy of linux_binprm::p
thus must be adjusted when that array is copied to the user stack.
Without that adjustment the value passed by the NOMMU kernel to the ELF
program in the AT_EXECFN entry of the aux array doesn't make any sense
and it may break programs that try to access memory pointed to by that
entry.

Adjust linux_binprm::exec before the successful return from the
transfer_args_to_stack().

Cc: <stable@vger.kernel.org>
Fixes: b6a2fea393 ("mm: variable length argument support")
Fixes: 5edc2a5123 ("binfmt_elf_fdpic: wire up AT_EXECFD, AT_EXECFN, AT_SECURE")
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Link: https://lore.kernel.org/r/20240320182607.1472887-1-jcmvbkbc@gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org>
2024-03-21 10:05:47 -07:00
Linus Torvalds
b32273ee89 execve updates for v6.9-rc1
- Drop needless error path code in remove_arg_zero() (Li kunyu, Kees Cook)
 
 - binfmt_elf_efpic: Don't use missing interpreter's properties (Max Filippov)
 
 - Use /bin/bash for execveat selftests
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Merge tag 'execve-v6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull execve updates from Kees Cook:

 - Drop needless error path code in remove_arg_zero() (Li kunyu, Kees
   Cook)

 - binfmt_elf_efpic: Don't use missing interpreter's properties (Max
   Filippov)

 - Use /bin/bash for execveat selftests

* tag 'execve-v6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  exec: Simplify remove_arg_zero() error path
  selftests/exec: Perform script checks with /bin/bash
  exec: Delete unnecessary statements in remove_arg_zero()
  fs: binfmt_elf_efpic: don't use missing interpreter's properties
2024-03-12 14:45:12 -07:00
Linus Torvalds
b5683a37c8 vfs-6.9.pidfd
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Merge tag 'vfs-6.9.pidfd' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull pdfd updates from Christian Brauner:

 - Until now pidfds could only be created for thread-group leaders but
   not for threads. There was no technical reason for this. We simply
   had no users that needed support for this. Now we do have users that
   need support for this.

   This introduces a new PIDFD_THREAD flag for pidfd_open(). If that
   flag is set pidfd_open() creates a pidfd that refers to a specific
   thread.

   In addition, we now allow clone() and clone3() to be called with
   CLONE_PIDFD | CLONE_THREAD which wasn't possible before.

   A pidfd that refers to an individual thread differs from a pidfd that
   refers to a thread-group leader:

    (1) Pidfds are pollable. A task may poll a pidfd and get notified
        when the task has exited.

        For thread-group leader pidfds the polling task is woken if the
        thread-group is empty. In other words, if the thread-group
        leader task exits when there are still threads alive in its
        thread-group the polling task will not be woken when the
        thread-group leader exits but rather when the last thread in the
        thread-group exits.

        For thread-specific pidfds the polling task is woken if the
        thread exits.

    (2) Passing a thread-group leader pidfd to pidfd_send_signal() will
        generate thread-group directed signals like kill(2) does.

        Passing a thread-specific pidfd to pidfd_send_signal() will
        generate thread-specific signals like tgkill(2) does.

        The default scope of the signal is thus determined by the type
        of the pidfd.

        Since use-cases exist where the default scope of the provided
        pidfd needs to be overriden the following flags are added to
        pidfd_send_signal():

         - PIDFD_SIGNAL_THREAD
           Send a thread-specific signal.

         - PIDFD_SIGNAL_THREAD_GROUP
           Send a thread-group directed signal.

         - PIDFD_SIGNAL_PROCESS_GROUP
           Send a process-group directed signal.

        The scope change will only work if the struct pid is actually
        used for this scope.

        For example, in order to send a thread-group directed signal the
        provided pidfd must be used as a thread-group leader and
        similarly for PIDFD_SIGNAL_PROCESS_GROUP the struct pid must be
        used as a process group leader.

 - Move pidfds from the anonymous inode infrastructure to a tiny pseudo
   filesystem. This will unblock further work that we weren't able to do
   simply because of the very justified limitations of anonymous inodes.
   Moving pidfds to a tiny pseudo filesystem allows for statx on pidfds
   to become useful for the first time. They can now be compared by
   inode number which are unique for the system lifetime.

   Instead of stashing struct pid in file->private_data we can now stash
   it in inode->i_private. This makes it possible to introduce concepts
   that operate on a process once all file descriptors have been closed.
   A concrete example is kill-on-last-close. Another side-effect is that
   file->private_data is now freed up for per-file options for pidfds.

   Now, each struct pid will refer to a different inode but the same
   struct pid will refer to the same inode if it's opened multiple
   times. In contrast to now where each struct pid refers to the same
   inode.

   The tiny pseudo filesystem is not visible anywhere in userspace
   exactly like e.g., pipefs and sockfs. There's no lookup, there's no
   complex inode operations, nothing. Dentries and inodes are always
   deleted when the last pidfd is closed.

   We allocate a new inode and dentry for each struct pid and we reuse
   that inode and dentry for all pidfds that refer to the same struct
   pid. The code is entirely optional and fairly small. If it's not
   selected we fallback to anonymous inodes. Heavily inspired by nsfs.

   The dentry and inode allocation mechanism is moved into generic
   infrastructure that is now shared between nsfs and pidfs. The
   path_from_stashed() helper must be provided with a stashing location,
   an inode number, a mount, and the private data that is supposed to be
   used and it will provide a path that can be passed to dentry_open().

   The helper will try retrieve an existing dentry from the provided
   stashing location. If a valid dentry is found it is reused. If not a
   new one is allocated and we try to stash it in the provided location.
   If this fails we retry until we either find an existing dentry or the
   newly allocated dentry could be stashed. Subsequent openers of the
   same namespace or task are then able to reuse it.

 - Currently it is only possible to get notified when a task has exited,
   i.e., become a zombie and userspace gets notified with EPOLLIN. We
   now also support waiting until the task has been reaped, notifying
   userspace with EPOLLHUP.

 - Ensure that ESRCH is reported for getfd if a task is exiting instead
   of the confusing EBADF.

 - Various smaller cleanups to pidfd functions.

* tag 'vfs-6.9.pidfd' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (23 commits)
  libfs: improve path_from_stashed()
  libfs: add stashed_dentry_prune()
  libfs: improve path_from_stashed() helper
  pidfs: convert to path_from_stashed() helper
  nsfs: convert to path_from_stashed() helper
  libfs: add path_from_stashed()
  pidfd: add pidfs
  pidfd: move struct pidfd_fops
  pidfd: allow to override signal scope in pidfd_send_signal()
  pidfd: change pidfd_send_signal() to respect PIDFD_THREAD
  signal: fill in si_code in prepare_kill_siginfo()
  selftests: add ESRCH tests for pidfd_getfd()
  pidfd: getfd should always report ESRCH if a task is exiting
  pidfd: clone: allow CLONE_THREAD | CLONE_PIDFD together
  pidfd: exit: kill the no longer used thread_group_exited()
  pidfd: change do_notify_pidfd() to use __wake_up(poll_to_key(EPOLLIN))
  pid: kill the obsolete PIDTYPE_PID code in transfer_pid()
  pidfd: kill the no longer needed do_notify_pidfd() in de_thread()
  pidfd_poll: report POLLHUP when pid_task() == NULL
  pidfd: implement PIDFD_THREAD flag for pidfd_open()
  ...
2024-03-11 10:21:06 -07:00
Kees Cook
725d502612 exec: Simplify remove_arg_zero() error path
We don't need the "out" label any more, so remove "ret" and return
directly on error.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: linux-mm@kvack.org
Cc: linux-fsdevel@vger.kernel.org
2024-03-09 13:46:30 -08:00
Li kunyu
d3f0d7bbae exec: Delete unnecessary statements in remove_arg_zero()
'ret=0; ' In actual operation, the ret was not modified, so this
sentence can be removed.

Signed-off-by: Li kunyu <kunyu@nfschina.com>
Link: https://lore.kernel.org/r/20240220052426.62018-1-kunyu@nfschina.com
Signed-off-by: Kees Cook <keescook@chromium.org>
2024-02-23 17:07:31 -08:00
Oleg Nesterov
90f92b68c9 pidfd: kill the no longer needed do_notify_pidfd() in de_thread()
Now that __change_pid() does wake_up_all(&pid->wait_pidfd) we can kill
do_notify_pidfd(leader) in de_thread(), it calls release_task(leader)
right after that and this implies detach_pid(leader, PIDTYPE_PID).

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20240202131248.GA26022@redhat.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-02-02 14:57:53 +01:00
Oleg Nesterov
64bef697d3 pidfd: implement PIDFD_THREAD flag for pidfd_open()
With this flag:

	- pidfd_open() doesn't require that the target task must be
	  a thread-group leader

	- pidfd_poll() succeeds when the task exits and becomes a
	  zombie (iow, passes exit_notify()), even if it is a leader
	  and thread-group is not empty.

	  This means that the behaviour of pidfd_poll(PIDFD_THREAD,
	  pid-of-group-leader) is not well defined if it races with
	  exec() from its sub-thread; pidfd_poll() can succeed or not
	  depending on whether pidfd_task_exited() is called before
	  or after exchange_tids().

	  Perhaps we can improve this behaviour later, pidfd_poll()
	  can probably take sig->group_exec_task into account. But
	  this doesn't really differ from the case when the leader
	  exits before other threads (so pidfd_poll() succeeds) and
	  then another thread execs and pidfd_poll() will block again.

thread_group_exited() is no longer used, perhaps it can die.

Co-developed-by: Tycho Andersen <tycho@tycho.pizza>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20240131132602.GA23641@redhat.com
Tested-by: Tycho Andersen <tandersen@netflix.com>
Reviewed-by: Tycho Andersen <tandersen@netflix.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-02-02 13:12:28 +01:00
Linus Torvalds
cf10015a24 execve fixes for v6.8-rc2
- Fix error handling in begin_new_exec() (Bernd Edlinger)
 
 - MAINTAINERS: specifically mention ELF (Alexey Dobriyan)
 
 - Various cleanups related to earlier open() (Askar Safin, Kees Cook)
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Merge tag 'execve-v6.8-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull execve fixes from Kees Cook:

 - Fix error handling in begin_new_exec() (Bernd Edlinger)

 - MAINTAINERS: specifically mention ELF (Alexey Dobriyan)

 - Various cleanups related to earlier open() (Askar Safin, Kees Cook)

* tag 'execve-v6.8-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  exec: Distinguish in_execve from in_exec
  exec: Fix error handling in begin_new_exec()
  exec: Add do_close_execat() helper
  exec: remove useless comment
  ELF, MAINTAINERS: specifically mention ELF
2024-01-24 13:32:29 -08:00
Linus Torvalds
3eab830189 uselib: remove use of __FMODE_EXEC
Jann Horn points out that uselib() really shouldn't trigger the new
FMODE_EXEC logic introduced by commit 4759ff71f2 ("exec: __FMODE_EXEC
instead of in_execve for LSMs").

In fact, it shouldn't even have ever triggered the old pre-existing
logic for __FMODE_EXEC (like the NFS code that makes executables not
need read permissions).  Unlike a real execve(), that can work even with
files that are purely executable by the user (not readable), uselib()
has that MAY_READ requirement becasue it's really just a convenience
wrapper around mmap() for legacy shared libraries.

The whole FMODE_EXEC bit was originally introduced by commit
b500531e6f ("[PATCH] Introduce FMODE_EXEC file flag"), primarily to
give ETXTBUSY error returns for distributed filesystems.

It has since grown a few other warts (like that NFS thing), but there
really isn't any reason to use it for uselib(), and now that we are
trying to use it to replace the horrid 'tsk->in_execve' flag, it's
actively wrong.

Of course, as Jann Horn also points out, nobody should be enabling
CONFIG_USELIB in the first place in this day and age, but that's a
different discussion entirely.

Reported-by: Jann Horn <jannh@google.com>
Fixes: 4759ff71f2 ("exec: __FMODE_EXEC instead of in_execve for LSMs")
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2024-01-24 13:12:20 -08:00
Kees Cook
90383cc078 exec: Distinguish in_execve from in_exec
Just to help distinguish the fs->in_exec flag from the current->in_execve
flag, add comments in check_unsafe_exec() and copy_fs() for more
context. Also note that in_execve is only used by TOMOYO now.

Cc: Kentaro Takeda <takedakn@nttdata.co.jp>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-mm@kvack.org
Signed-off-by: Kees Cook <keescook@chromium.org>
2024-01-24 11:48:52 -08:00
Bernd Edlinger
84c39ec57d exec: Fix error handling in begin_new_exec()
If get_unused_fd_flags() fails, the error handling is incomplete because
bprm->cred is already set to NULL, and therefore free_bprm will not
unlock the cred_guard_mutex. Note there are two error conditions which
end up here, one before and one after bprm->cred is cleared.

Fixes: b8a61c9e7b ("exec: Generic execfd support")
Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Acked-by: Eric W. Biederman <ebiederm@xmission.com>
Link: https://lore.kernel.org/r/AS8P193MB128517ADB5EFF29E04389EDAE4752@AS8P193MB1285.EURP193.PROD.OUTLOOK.COM
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
2024-01-22 12:51:31 -08:00
Kees Cook
bdd8f62431 exec: Add do_close_execat() helper
Consolidate the calls to allow_write_access()/fput() into a single
place, since we repeat this code pattern. Add comments around the
callers for the details on it.

Link: https://lore.kernel.org/r/202209161637.9EDAF6B18@keescook
Signed-off-by: Kees Cook <keescook@chromium.org>
2024-01-22 11:45:39 -08:00
Askar Safin
8788a17c23 exec: remove useless comment
Function name is wrong and the comment tells us nothing

Signed-off-by: Askar Safin <safinaskar@zohomail.com>
Link: https://lore.kernel.org/r/20240109030801.31827-1-safinaskar@zohomail.com
Signed-off-by: Kees Cook <keescook@chromium.org>
2024-01-22 11:27:25 -08:00
Linus Torvalds
978ffcbf00 execve: open the executable file before doing anything else
No point in allocating a new mm, counting arguments and environment
variables etc if we're just going to return ENOENT.

This patch does expose the fact that 'do_filp_open()' that execve() uses
is still unnecessarily expensive in the failure case, because it
allocates the 'struct file *' early, even if the path lookup (which is
heavily optimized) fails.

So that remains an unnecessary cost in the "no such executable" case,
but it's a separate issue.  Regardless, I do not want to do _both_ a
filename_lookup() and a later do_filp_open() like the origin patch by
Josh Triplett did in [1].

Reported-by: Josh Triplett <josh@joshtriplett.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/lkml/5c7333ea4bec2fad1b47a8fa2db7c31e4ffc4f14.1663334978.git.josh@joshtriplett.org/ [1]
Link: https://lore.kernel.org/lkml/202209161637.9EDAF6B18@keescook/
Link: https://lore.kernel.org/lkml/CAHk-=wgznerM-xs+x+krDfE7eVBiy_HOam35rbsFMMOwvYuEKQ@mail.gmail.com/
Link: https://lore.kernel.org/lkml/CAHk-=whf9qLO8ipps4QhmS0BkM8mtWJhvnuDSdtw5gFjhzvKNA@mail.gmail.com/
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2024-01-20 12:15:43 -08:00
Linus Torvalds
a05aea98d4 sysctl-6.8-rc1
To help make the move of sysctls out of kernel/sysctl.c not incur a size
 penalty sysctl has been changed to allow us to not require the sentinel, the
 final empty element on the sysctl array. Joel Granados has been doing all this
 work. On the v6.6 kernel we got the major infrastructure changes required to
 support this. For v6.7 we had all arch/ and drivers/ modified to remove
 the sentinel. For v6.8-rc1 we get a few more updates for fs/ directory only.
 The kernel/ directory is left but we'll save that for v6.9-rc1 as those patches
 are still being reviewed. After that we then can expect also the removal of the
 no longer needed check for procname == NULL.
 
 Let us recap the purpose of this work:
 
   - this helps reduce the overall build time size of the kernel and run time
     memory consumed by the kernel by about ~64 bytes per array
   - the extra 64-byte penalty is no longer inncurred now when we move sysctls
     out from kernel/sysctl.c to their own files
 
 Thomas Weißschuh also sent a few cleanups, for v6.9-rc1 we expect to see further
 work by Thomas Weißschuh with the constificatin of the struct ctl_table.
 
 Due to Joel Granados's work, and to help bring in new blood, I have suggested
 for him to become a maintainer and he's accepted. So for v6.9-rc1 I look forward
 to seeing him sent you a pull request for further sysctl changes. This also
 removes Iurii Zaikin as a maintainer as he has moved on to other projects and
 has had no time to help at all.
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Merge tag 'sysctl-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux

Pull sysctl updates from Luis Chamberlain:
 "To help make the move of sysctls out of kernel/sysctl.c not incur a
  size penalty sysctl has been changed to allow us to not require the
  sentinel, the final empty element on the sysctl array. Joel Granados
  has been doing all this work.

  In the v6.6 kernel we got the major infrastructure changes required to
  support this. For v6.7 we had all arch/ and drivers/ modified to
  remove the sentinel. For v6.8-rc1 we get a few more updates for fs/
  directory only.

  The kernel/ directory is left but we'll save that for v6.9-rc1 as
  those patches are still being reviewed. After that we then can expect
  also the removal of the no longer needed check for procname == NULL.

  Let us recap the purpose of this work:

   - this helps reduce the overall build time size of the kernel and run
     time memory consumed by the kernel by about ~64 bytes per array

   - the extra 64-byte penalty is no longer inncurred now when we move
     sysctls out from kernel/sysctl.c to their own files

  Thomas Weißschuh also sent a few cleanups, for v6.9-rc1 we expect to
  see further work by Thomas Weißschuh with the constificatin of the
  struct ctl_table.

  Due to Joel Granados's work, and to help bring in new blood, I have
  suggested for him to become a maintainer and he's accepted. So for
  v6.9-rc1 I look forward to seeing him sent you a pull request for
  further sysctl changes. This also removes Iurii Zaikin as a maintainer
  as he has moved on to other projects and has had no time to help at
  all"

* tag 'sysctl-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux:
  sysctl: remove struct ctl_path
  sysctl: delete unused define SYSCTL_PERM_EMPTY_DIR
  coda: Remove the now superfluous sentinel elements from ctl_table array
  sysctl: Remove the now superfluous sentinel elements from ctl_table array
  fs: Remove the now superfluous sentinel elements from ctl_table array
  cachefiles: Remove the now superfluous sentinel element from ctl_table array
  sysclt: Clarify the results of selftest run
  sysctl: Add a selftest for handling empty dirs
  sysctl: Fix out of bounds access for empty sysctl registers
  MAINTAINERS: Add Joel Granados as co-maintainer for proc sysctl
  MAINTAINERS: remove Iurii Zaikin from proc sysctl
2024-01-10 17:44:36 -08:00
Linus Torvalds
78273df7f6 header cleanups for 6.8
The goal is to get sched.h down to a type only header, so the main thing
 happening in this patchset is splitting out various _types.h headers and
 dependency fixups, as well as moving some things out of sched.h to
 better locations.
 
 This is prep work for the memory allocation profiling patchset which
 adds new sched.h interdepencencies.
 
 Testing - it's been in -next, and fixes from pretty much all
 architectures have percolated in - nothing major.
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Merge tag 'header_cleanup-2024-01-10' of https://evilpiepirate.org/git/bcachefs

Pull header cleanups from Kent Overstreet:
 "The goal is to get sched.h down to a type only header, so the main
  thing happening in this patchset is splitting out various _types.h
  headers and dependency fixups, as well as moving some things out of
  sched.h to better locations.

  This is prep work for the memory allocation profiling patchset which
  adds new sched.h interdepencencies"

* tag 'header_cleanup-2024-01-10' of https://evilpiepirate.org/git/bcachefs: (51 commits)
  Kill sched.h dependency on rcupdate.h
  kill unnecessary thread_info.h include
  Kill unnecessary kernel.h include
  preempt.h: Kill dependency on list.h
  rseq: Split out rseq.h from sched.h
  LoongArch: signal.c: add header file to fix build error
  restart_block: Trim includes
  lockdep: move held_lock to lockdep_types.h
  sem: Split out sem_types.h
  uidgid: Split out uidgid_types.h
  seccomp: Split out seccomp_types.h
  refcount: Split out refcount_types.h
  uapi/linux/resource.h: fix include
  x86/signal: kill dependency on time.h
  syscall_user_dispatch.h: split out *_types.h
  mm_types_task.h: Trim dependencies
  Split out irqflags_types.h
  ipc: Kill bogus dependency on spinlock.h
  shm: Slim down dependencies
  workqueue: Split out workqueue_types.h
  ...
2024-01-10 16:43:55 -08:00
Joel Granados
9d5b947535 fs: Remove the now superfluous sentinel elements from ctl_table array
This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels) which
will reduce the overall build time size of the kernel and run time
memory bloat by ~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)

Remove sentinel elements ctl_table struct. Special attention was placed in
making sure that an empty directory for fs/verity was created when
CONFIG_FS_VERITY_BUILTIN_SIGNATURES is not defined. In this case we use the
register sysctl call that expects a size.

Signed-off-by: Joel Granados <j.granados@samsung.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
2023-12-28 04:57:57 -08:00
Kent Overstreet
932562a604 rseq: Split out rseq.h from sched.h
We're trying to get sched.h down to more or less just types only, not
code - rseq can live in its own header.

This helps us kill the dependency on preempt.h in sched.h.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-27 11:49:56 -05:00
Oleg Nesterov
61a7a5e25f introduce for_other_threads(p, t)
Cosmetic, but imho it makes the usage look more clear and simple, the new
helper doesn't require to initialize "t".

After this change while_each_thread() has only 3 users, and it is only
used in the do/while loops.

Link: https://lkml.kernel.org/r/20231030155710.GA9095@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-12-10 17:21:25 -08:00
Joel Fernandes (Google)
b1e5a3dee2 mm/mremap: allow moves within the same VMA for stack moves
For the stack move happening in shift_arg_pages(), the move is happening
within the same VMA which spans the old and new ranges.

In case the aligned address happens to fall within that VMA, allow such
moves and don't abort the mremap alignment optimization.

In the regular non-stack mremap case, we cannot allow any such moves as
will end up destroying some part of the mapping (either the source of the
move, or part of the existing mapping).  So just avoid it for stack moves.

Link: https://lkml.kernel.org/r/20230903151328.2981432-3-joel@joelfernandes.org
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-10-04 10:32:20 -07:00
Mateusz Guzik
bc0c335760 mm: remove remnants of SPLIT_RSS_COUNTING
The feature got retired in f1a7941243 ("mm: convert mm's rss stats into
percpu_counter"), but the patch failed to fully clean it up.

Link: https://lkml.kernel.org/r/20230823170556.2281747-1-mjguzik@gmail.com
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-10-04 10:32:20 -07:00
Linus Torvalds
d68b4b6f30 - An extensive rework of kexec and crash Kconfig from Eric DeVolder
("refactor Kconfig to consolidate KEXEC and CRASH options").
 
 - kernel.h slimming work from Andy Shevchenko ("kernel.h: Split out a
   couple of macros to args.h").
 
 - gdb feature work from Kuan-Ying Lee ("Add GDB memory helper
   commands").
 
 - vsprintf inclusion rationalization from Andy Shevchenko
   ("lib/vsprintf: Rework header inclusions").
 
 - Switch the handling of kdump from a udev scheme to in-kernel handling,
   by Eric DeVolder ("crash: Kernel handling of CPU and memory hot
   un/plug").
 
 - Many singleton patches to various parts of the tree
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Merge tag 'mm-nonmm-stable-2023-08-28-22-48' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull non-MM updates from Andrew Morton:

 - An extensive rework of kexec and crash Kconfig from Eric DeVolder
   ("refactor Kconfig to consolidate KEXEC and CRASH options")

 - kernel.h slimming work from Andy Shevchenko ("kernel.h: Split out a
   couple of macros to args.h")

 - gdb feature work from Kuan-Ying Lee ("Add GDB memory helper
   commands")

 - vsprintf inclusion rationalization from Andy Shevchenko
   ("lib/vsprintf: Rework header inclusions")

 - Switch the handling of kdump from a udev scheme to in-kernel
   handling, by Eric DeVolder ("crash: Kernel handling of CPU and memory
   hot un/plug")

 - Many singleton patches to various parts of the tree

* tag 'mm-nonmm-stable-2023-08-28-22-48' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (81 commits)
  document while_each_thread(), change first_tid() to use for_each_thread()
  drivers/char/mem.c: shrink character device's devlist[] array
  x86/crash: optimize CPU changes
  crash: change crash_prepare_elf64_headers() to for_each_possible_cpu()
  crash: hotplug support for kexec_load()
  x86/crash: add x86 crash hotplug support
  crash: memory and CPU hotplug sysfs attributes
  kexec: exclude elfcorehdr from the segment digest
  crash: add generic infrastructure for crash hotplug support
  crash: move a few code bits to setup support of crash hotplug
  kstrtox: consistently use _tolower()
  kill do_each_thread()
  nilfs2: fix WARNING in mark_buffer_dirty due to discarded buffer reuse
  scripts/bloat-o-meter: count weak symbol sizes
  treewide: drop CONFIG_EMBEDDED
  lockdep: fix static memory detection even more
  lib/vsprintf: declare no_hash_pointers in sprintf.h
  lib/vsprintf: split out sprintf() and friends
  kernel/fork: stop playing lockless games for exe_file replacement
  adfs: delete unused "union adfs_dirtail" definition
  ...
2023-08-29 14:53:51 -07:00
Mateusz Guzik
a7031f1452 kernel/fork: stop playing lockless games for exe_file replacement
xchg originated in 6e399cd144 ("prctl: avoid using mmap_sem for exe_file
serialization").  While the commit message does not explain *why* the
change, I found the original submission [1] which ultimately claims it
cleans things up by removing dependency of exe_file on the semaphore.

However, fe69d560b5 ("kernel/fork: always deny write access to current
MM exe_file") added a semaphore up/down cycle to synchronize the state of
exe_file against fork, defeating the point of the original change.

This is on top of semaphore trips already present both in the replacing
function and prctl (the only consumer).

Normally replacing exe_file does not happen for busy processes, thus
write-locking is not an impediment to performance in the intended use
case.  If someone keeps invoking the routine for a busy processes they are
trying to play dirty and that's another reason to avoid any trickery.

As such I think the atomic here only adds complexity for no benefit.

Just write-lock around the replacement.

I also note that replacement races against the mapping check loop as
nothing synchronizes actual assignment with with said checks but I am not
addressing it in this patch.  (Is the loop of any use to begin with?)

Link: https://lore.kernel.org/linux-mm/1424979417.10344.14.camel@stgolabs.net/ [1]
Link: https://lkml.kernel.org/r/20230814172140.1777161-1-mjguzik@gmail.com
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: "Christian Brauner (Microsoft)" <brauner@kernel.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-08-21 13:46:24 -07:00
Liam R. Howlett
b5df092264 mm: set up vma iterator for vma_iter_prealloc() calls
Set the correct limits for vma_iter_prealloc() calls so that the maple
tree can be smarter about how many nodes are needed.

Link: https://lkml.kernel.org/r/20230724183157.3939892-11-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Peng Zhang <zhangpeng.00@bytedance.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-08-18 10:12:49 -07:00
Linus Torvalds
18c9901d74 \n
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Merge tag 'fsnotify_for_v6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs

Pull fsnotify updates from Jan Kara:

 - Support for fanotify events returning file handles for filesystems
   not exportable via NFS

 - Improved error handling exportfs functions

 - Add missing FS_OPEN events when unusual open helpers are used

* tag 'fsnotify_for_v6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  fsnotify: move fsnotify_open() hook into do_dentry_open()
  exportfs: check for error return value from exportfs_encode_*()
  fanotify: support reporting non-decodeable file handles
  exportfs: allow exporting non-decodeable file handles to userspace
  exportfs: add explicit flag to request non-decodeable file handles
  exportfs: change connectable argument to bit flags
2023-06-29 13:31:44 -07:00
Linus Torvalds
9471f1f2f5 Merge branch 'expand-stack'
This modifies our user mode stack expansion code to always take the
mmap_lock for writing before modifying the VM layout.

It's actually something we always technically should have done, but
because we didn't strictly need it, we were being lazy ("opportunistic"
sounds so much better, doesn't it?) about things, and had this hack in
place where we would extend the stack vma in-place without doing the
proper locking.

And it worked fine.  We just needed to change vm_start (or, in the case
of grow-up stacks, vm_end) and together with some special ad-hoc locking
using the anon_vma lock and the mm->page_table_lock, it all was fairly
straightforward.

That is, it was all fine until Ruihan Li pointed out that now that the
vma layout uses the maple tree code, we *really* don't just change
vm_start and vm_end any more, and the locking really is broken.  Oops.

It's not actually all _that_ horrible to fix this once and for all, and
do proper locking, but it's a bit painful.  We have basically three
different cases of stack expansion, and they all work just a bit
differently:

 - the common and obvious case is the page fault handling. It's actually
   fairly simple and straightforward, except for the fact that we have
   something like 24 different versions of it, and you end up in a maze
   of twisty little passages, all alike.

 - the simplest case is the execve() code that creates a new stack.
   There are no real locking concerns because it's all in a private new
   VM that hasn't been exposed to anybody, but lockdep still can end up
   unhappy if you get it wrong.

 - and finally, we have GUP and page pinning, which shouldn't really be
   expanding the stack in the first place, but in addition to execve()
   we also use it for ptrace(). And debuggers do want to possibly access
   memory under the stack pointer and thus need to be able to expand the
   stack as a special case.

None of these cases are exactly complicated, but the page fault case in
particular is just repeated slightly differently many many times.  And
ia64 in particular has a fairly complicated situation where you can have
both a regular grow-down stack _and_ a special grow-up stack for the
register backing store.

So to make this slightly more manageable, the bulk of this series is to
first create a helper function for the most common page fault case, and
convert all the straightforward architectures to it.

Thus the new 'lock_mm_and_find_vma()' helper function, which ends up
being used by x86, arm, powerpc, mips, riscv, alpha, arc, csky, hexagon,
loongarch, nios2, sh, sparc32, and xtensa.  So we not only convert more
than half the architectures, we now have more shared code and avoid some
of those twisty little passages.

And largely due to this common helper function, the full diffstat of
this series ends up deleting more lines than it adds.

That still leaves eight architectures (ia64, m68k, microblaze, openrisc,
parisc, s390, sparc64 and um) that end up doing 'expand_stack()'
manually because they are doing something slightly different from the
normal pattern.  Along with the couple of special cases in execve() and
GUP.

So there's a couple of patches that first create 'locked' helper
versions of the stack expansion functions, so that there's a obvious
path forward in the conversion.  The execve() case is then actually
pretty simple, and is a nice cleanup from our old "grow-up stackls are
special, because at execve time even they grow down".

The #ifdef CONFIG_STACK_GROWSUP in that code just goes away, because
it's just more straightforward to write out the stack expansion there
manually, instead od having get_user_pages_remote() do it for us in some
situations but not others and have to worry about locking rules for GUP.

And the final step is then to just convert the remaining odd cases to a
new world order where 'expand_stack()' is called with the mmap_lock held
for reading, but where it might drop it and upgrade it to a write, only
to return with it held for reading (in the success case) or with it
completely dropped (in the failure case).

In the process, we remove all the stack expansion from GUP (where
dropping the lock wouldn't be ok without special rules anyway), and add
it in manually to __access_remote_vm() for ptrace().

Thanks to Adrian Glaubitz and Frank Scheiner who tested the ia64 cases.
Everything else here felt pretty straightforward, but the ia64 rules for
stack expansion are really quite odd and very different from everything
else.  Also thanks to Vegard Nossum who caught me getting one of those
odd conditions entirely the wrong way around.

Anyway, I think I want to actually move all the stack expansion code to
a whole new file of its own, rather than have it split up between
mm/mmap.c and mm/memory.c, but since this will have to be backported to
the initial maple tree vma introduction anyway, I tried to keep the
patches _fairly_ minimal.

Also, while I don't think it's valid to expand the stack from GUP, the
final patch in here is a "warn if some crazy GUP user wants to try to
expand the stack" patch.  That one will be reverted before the final
release, but it's left to catch any odd cases during the merge window
and release candidates.

Reported-by: Ruihan Li <lrh2000@pku.edu.cn>

* branch 'expand-stack':
  gup: add warning if some caller would seem to want stack expansion
  mm: always expand the stack with the mmap write lock held
  execve: expand new process stack manually ahead of time
  mm: make find_extend_vma() fail if write lock not held
  powerpc/mm: convert coprocessor fault to lock_mm_and_find_vma()
  mm/fault: convert remaining simple cases to lock_mm_and_find_vma()
  arm/mm: Convert to using lock_mm_and_find_vma()
  riscv/mm: Convert to using lock_mm_and_find_vma()
  mips/mm: Convert to using lock_mm_and_find_vma()
  powerpc/mm: Convert to using lock_mm_and_find_vma()
  arm64/mm: Convert to using lock_mm_and_find_vma()
  mm: make the page fault mmap locking killable
  mm: introduce new 'lock_mm_and_find_vma()' page fault helper
2023-06-28 20:35:21 -07:00
Linus Torvalds
8d7071af89 mm: always expand the stack with the mmap write lock held
This finishes the job of always holding the mmap write lock when
extending the user stack vma, and removes the 'write_locked' argument
from the vm helper functions again.

For some cases, we just avoid expanding the stack at all: drivers and
page pinning really shouldn't be extending any stacks.  Let's see if any
strange users really wanted that.

It's worth noting that architectures that weren't converted to the new
lock_mm_and_find_vma() helper function are left using the legacy
"expand_stack()" function, but it has been changed to drop the mmap_lock
and take it for writing while expanding the vma.  This makes it fairly
straightforward to convert the remaining architectures.

As a result of dropping and re-taking the lock, the calling conventions
for this function have also changed, since the old vma may no longer be
valid.  So it will now return the new vma if successful, and NULL - and
the lock dropped - if the area could not be extended.

Tested-by: Vegard Nossum <vegard.nossum@oracle.com>
Tested-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> # ia64
Tested-by: Frank Scheiner <frank.scheiner@web.de> # ia64
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2023-06-27 09:41:30 -07:00
Linus Torvalds
f313c51d26 execve: expand new process stack manually ahead of time
This is a small step towards a model where GUP itself would not expand
the stack, and any user that needs GUP to not look up existing mappings,
but actually expand on them, would have to do so manually before-hand,
and with the mm lock held for writing.

It turns out that execve() already did almost exactly that, except it
didn't take the mm lock at all (it's single-threaded so no locking
technically needed, but it could cause lockdep errors).  And it only did
it for the CONFIG_STACK_GROWSUP case, since in that case GUP has
obviously never expanded the stack downwards.

So just make that CONFIG_STACK_GROWSUP case do the right thing with
locking, and enable it generally.  This will eventually help GUP, and in
the meantime avoids a special case and the lockdep issue.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2023-06-24 14:13:55 -07:00
Liam R. Howlett
f440fa1ac9 mm: make find_extend_vma() fail if write lock not held
Make calls to extend_vma() and find_extend_vma() fail if the write lock
is required.

To avoid making this a flag-day event, this still allows the old
read-locking case for the trivial situations, and passes in a flag to
say "is it write-locked".  That way write-lockers can say "yes, I'm
being careful", and legacy users will continue to work in all the common
cases until they have been fully converted to the new world order.

Co-Developed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2023-06-24 14:13:54 -07:00
Amir Goldstein
7b8c9d7bb4 fsnotify: move fsnotify_open() hook into do_dentry_open()
fsnotify_open() hook is called only from high level system calls
context and not called for the very many helpers to open files.

This may makes sense for many of the special file open cases, but it is
inconsistent with fsnotify_close() hook that is called for every last
fput() of on a file object with FMODE_OPENED.

As a result, it is possible to observe ACCESS, MODIFY and CLOSE events
without ever observing an OPEN event.

Fix this inconsistency by replacing all the fsnotify_open() hooks with
a single hook inside do_dentry_open().

If there are special cases that would like to opt-out of the possible
overhead of fsnotify() call in fsnotify_open(), they would probably also
want to avoid the overhead of fsnotify() call in the rest of the fsnotify
hooks, so they should be opening that file with the __FMODE_NONOTIFY flag.

However, in the majority of those cases, the s_fsnotify_connectors
optimization in fsnotify_parent() would be sufficient to avoid the
overhead of fsnotify() call anyway.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20230611122429.1499617-1-amir73il@gmail.com>
2023-06-12 10:43:45 +02:00
Lorenzo Stoakes
ca5e863233 mm/gup: remove vmas parameter from get_user_pages_remote()
The only instances of get_user_pages_remote() invocations which used the
vmas parameter were for a single page which can instead simply look up the
VMA directly. In particular:-

- __update_ref_ctr() looked up the VMA but did nothing with it so we simply
  remove it.

- __access_remote_vm() was already using vma_lookup() when the original
  lookup failed so by doing the lookup directly this also de-duplicates the
  code.

We are able to perform these VMA operations as we already hold the
mmap_lock in order to be able to call get_user_pages_remote().

As part of this work we add get_user_page_vma_remote() which abstracts the
VMA lookup, error handling and decrementing the page reference count should
the VMA lookup fail.

This forms part of a broader set of patches intended to eliminate the vmas
parameter altogether.

[akpm@linux-foundation.org: avoid passing NULL to PTR_ERR]
Link: https://lkml.kernel.org/r/d20128c849ecdbf4dd01cc828fcec32127ed939a.1684350871.git.lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> (for arm64)
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com> (for s390)
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Christian König <christian.koenig@amd.com>
Cc: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jarkko Sakkinen <jarkko@kernel.org>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: Sean Christopherson <seanjc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-09 16:25:26 -07:00
Linus Torvalds
d579c468d7 tracing updates for 6.4:
- User events are finally ready!
   After lots of collaboration between various parties, we finally locked
   down on a stable interface for user events that can also work with user
   space only tracing. This is implemented by telling the kernel (or user
   space library, but that part is user space only and not part of this
   patch set), where the variable is that the application uses to know if
   something is listening to the trace. There's also an interface to tell
   the kernel about these events, which will show up in the
   /sys/kernel/tracing/events/user_events/ directory, where it can be
    enabled. When it's enabled, the kernel will update the variable, to tell
   the application to start writing to the kernel.
   See https://lwn.net/Articles/927595/
 
 - Cleaned up the direct trampolines code to simplify arm64 addition of
   direct trampolines. Direct trampolines use the ftrace interface but
   instead of jumping to the ftrace trampoline, applications (mostly BPF)
   can register their own trampoline for performance reasons.
 
 - Some updates to the fprobe infrastructure. fprobes are more efficient than
   kprobes, as it does not need to save all the registers that kprobes on
   ftrace do. More work needs to be done before the fprobes will be exposed
   as dynamic events.
 
 - More updates to references to the obsolete path of
   /sys/kernel/debug/tracing for the new /sys/kernel/tracing path.
 
 - Add a seq_buf_do_printk() helper to seq_bufs, to print a large buffer line
   by line instead of all at once. There's users in production kernels that
   have a large data dump that originally used printk() directly, but the
   data dump was larger than what printk() allowed as a single print.
   Using seq_buf() to do the printing fixes that.
 
 - Add /sys/kernel/tracing/touched_functions that shows all functions that
   was every traced by ftrace or a direct trampoline. This is used for
   debugging issues where a traced function could have caused a crash by
   a bpf program or live patching.
 
 - Add a "fields" option that is similar to "raw" but outputs the fields of
   the events. It's easier to read by humans.
 
 - Some minor fixes and clean ups.
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Merge tag 'trace-v6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing updates from Steven Rostedt:

 - User events are finally ready!

   After lots of collaboration between various parties, we finally
   locked down on a stable interface for user events that can also work
   with user space only tracing.

   This is implemented by telling the kernel (or user space library, but
   that part is user space only and not part of this patch set), where
   the variable is that the application uses to know if something is
   listening to the trace.

   There's also an interface to tell the kernel about these events,
   which will show up in the /sys/kernel/tracing/events/user_events/
   directory, where it can be enabled.

   When it's enabled, the kernel will update the variable, to tell the
   application to start writing to the kernel.

   See https://lwn.net/Articles/927595/

 - Cleaned up the direct trampolines code to simplify arm64 addition of
   direct trampolines.

   Direct trampolines use the ftrace interface but instead of jumping to
   the ftrace trampoline, applications (mostly BPF) can register their
   own trampoline for performance reasons.

 - Some updates to the fprobe infrastructure. fprobes are more efficient
   than kprobes, as it does not need to save all the registers that
   kprobes on ftrace do. More work needs to be done before the fprobes
   will be exposed as dynamic events.

 - More updates to references to the obsolete path of
   /sys/kernel/debug/tracing for the new /sys/kernel/tracing path.

 - Add a seq_buf_do_printk() helper to seq_bufs, to print a large buffer
   line by line instead of all at once.

   There are users in production kernels that have a large data dump
   that originally used printk() directly, but the data dump was larger
   than what printk() allowed as a single print.

   Using seq_buf() to do the printing fixes that.

 - Add /sys/kernel/tracing/touched_functions that shows all functions
   that was every traced by ftrace or a direct trampoline. This is used
   for debugging issues where a traced function could have caused a
   crash by a bpf program or live patching.

 - Add a "fields" option that is similar to "raw" but outputs the fields
   of the events. It's easier to read by humans.

 - Some minor fixes and clean ups.

* tag 'trace-v6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (41 commits)
  ring-buffer: Sync IRQ works before buffer destruction
  tracing: Add missing spaces in trace_print_hex_seq()
  ring-buffer: Ensure proper resetting of atomic variables in ring_buffer_reset_online_cpus
  recordmcount: Fix memory leaks in the uwrite function
  tracing/user_events: Limit max fault-in attempts
  tracing/user_events: Prevent same address and bit per process
  tracing/user_events: Ensure bit is cleared on unregister
  tracing/user_events: Ensure write index cannot be negative
  seq_buf: Add seq_buf_do_printk() helper
  tracing: Fix print_fields() for __dyn_loc/__rel_loc
  tracing/user_events: Set event filter_type from type
  ring-buffer: Clearly check null ptr returned by rb_set_head_page()
  tracing: Unbreak user events
  tracing/user_events: Use print_format_fields() for trace output
  tracing/user_events: Align structs with tabs for readability
  tracing/user_events: Limit global user_event count
  tracing/user_events: Charge event allocs to cgroups
  tracing/user_events: Update documentation for ABI
  tracing/user_events: Use write ABI in example
  tracing/user_events: Add ABI self-test
  ...
2023-04-28 15:57:53 -07:00
Beau Belgrave
fd593511cd tracing/user_events: Track fork/exec/exit for mm lifetime
During tracefs discussions it was decided instead of requiring a mapping
within a user-process to track the lifetime of memory descriptors we
should hook the appropriate calls. Do this by adding the minimal stubs
required for task fork, exec, and exit. Currently this is just a NOP.
Future patches will implement these calls fully.

Link: https://lkml.kernel.org/r/20230328235219.203-3-beaub@linux.microsoft.com

Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-03-29 06:52:08 -04:00
Nicholas Piggin
aa464ba9a1 lazy tlb: introduce lazy tlb mm refcount helper functions
Add explicit _lazy_tlb annotated functions for lazy tlb mm refcounting. 
This makes the lazy tlb mm references more obvious, and allows the
refcounting scheme to be modified in later changes.  There is no
functional change with this patch.

Link: https://lkml.kernel.org/r/20230203071837.1136453-3-npiggin@gmail.com
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-03-28 16:20:08 -07:00