Commit Graph

892 Commits

Author SHA1 Message Date
Linus Torvalds
f4f27d0028 Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
Pull security subsystem updates from James Morris:
 "Highlights:

   - A new LSM, "LoadPin", from Kees Cook is added, which allows forcing
     of modules and firmware to be loaded from a specific device (this
     is from ChromeOS, where the device as a whole is verified
     cryptographically via dm-verity).

     This is disabled by default but can be configured to be enabled by
     default (don't do this if you don't know what you're doing).

   - Keys: allow authentication data to be stored in an asymmetric key.
     Lots of general fixes and updates.

   - SELinux: add restrictions for loading of kernel modules via
     finit_module().  Distinguish non-init user namespace capability
     checks.  Apply execstack check on thread stacks"

* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (48 commits)
  LSM: LoadPin: provide enablement CONFIG
  Yama: use atomic allocations when reporting
  seccomp: Fix comment typo
  ima: add support for creating files using the mknodat syscall
  ima: fix ima_inode_post_setattr
  vfs: forbid write access when reading a file into memory
  fs: fix over-zealous use of "const"
  selinux: apply execstack check on thread stacks
  selinux: distinguish non-init user namespace capability checks
  LSM: LoadPin for kernel file loading restrictions
  fs: define a string representation of the kernel_read_file_id enumeration
  Yama: consolidate error reporting
  string_helpers: add kstrdup_quotable_file
  string_helpers: add kstrdup_quotable_cmdline
  string_helpers: add kstrdup_quotable
  selinux: check ss_initialized before revalidating an inode label
  selinux: delay inode label lookup as long as possible
  selinux: don't revalidate an inode's label when explicitly setting it
  selinux: Change bool variable name to index.
  KEYS: Add KEYCTL_DH_COMPUTE command
  ...
2016-05-19 09:21:36 -07:00
Linus Torvalds
c52b76185b Merge branch 'work.const-path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull 'struct path' constification update from Al Viro:
 "'struct path' is passed by reference to a bunch of Linux security
  methods; in theory, there's nothing to stop them from modifying the
  damn thing and LSM community being what it is, sooner or later some
  enterprising soul is going to decide that it's a good idea.

  Let's remove the temptation and constify all of those..."

* 'work.const-path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  constify ima_d_path()
  constify security_sb_pivotroot()
  constify security_path_chroot()
  constify security_path_{link,rename}
  apparmor: remove useless checks for NULL ->mnt
  constify security_path_{mkdir,mknod,symlink}
  constify security_path_{unlink,rmdir}
  apparmor: constify common_perm_...()
  apparmor: constify aa_path_link()
  apparmor: new helper - common_path_perm()
  constify chmod_common/security_path_chmod
  constify security_sb_mount()
  constify chown_common/security_path_chown
  tomoyo: constify assorted struct path *
  apparmor_path_truncate(): path->mnt is never NULL
  constify vfs_truncate()
  constify security_path_truncate()
  [apparmor] constify struct path * in a bunch of helpers
2016-05-17 14:41:03 -07:00
Linus Torvalds
7f427d3a60 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull parallel filesystem directory handling update from Al Viro.

This is the main parallel directory work by Al that makes the vfs layer
able to do lookup and readdir in parallel within a single directory.
That's a big change, since this used to be all protected by the
directory inode mutex.

The inode mutex is replaced by an rwsem, and serialization of lookups of
a single name is done by a "in-progress" dentry marker.

The series begins with xattr cleanups, and then ends with switching
filesystems over to actually doing the readdir in parallel (switching to
the "iterate_shared()" that only takes the read lock).

A more detailed explanation of the process from Al Viro:
 "The xattr work starts with some acl fixes, then switches ->getxattr to
  passing inode and dentry separately.  This is the point where the
  things start to get tricky - that got merged into the very beginning
  of the -rc3-based #work.lookups, to allow untangling the
  security_d_instantiate() mess.  The xattr work itself proceeds to
  switch a lot of filesystems to generic_...xattr(); no complications
  there.

  After that initial xattr work, the series then does the following:

   - untangle security_d_instantiate()

   - convert a bunch of open-coded lookup_one_len_unlocked() to calls of
     that thing; one such place (in overlayfs) actually yields a trivial
     conflict with overlayfs fixes later in the cycle - overlayfs ended
     up switching to a variant of lookup_one_len_unlocked() sans the
     permission checks.  I would've dropped that commit (it gets
     overridden on merge from #ovl-fixes in #for-next; proper resolution
     is to use the variant in mainline fs/overlayfs/super.c), but I
     didn't want to rebase the damn thing - it was fairly late in the
     cycle...

   - some filesystems had managed to depend on lookup/lookup exclusion
     for *fs-internal* data structures in a way that would break if we
     relaxed the VFS exclusion.  Fixing hadn't been hard, fortunately.

   - core of that series - parallel lookup machinery, replacing
     ->i_mutex with rwsem, making lookup_slow() take it only shared.  At
     that point lookups happen in parallel; lookups on the same name
     wait for the in-progress one to be done with that dentry.

     Surprisingly little code, at that - almost all of it is in
     fs/dcache.c, with fs/namei.c changes limited to lookup_slow() -
     making it use the new primitive and actually switching to locking
     shared.

   - parallel readdir stuff - first of all, we provide the exclusion on
     per-struct file basis, same as we do for read() vs lseek() for
     regular files.  That takes care of most of the needed exclusion in
     readdir/readdir; however, these guys are trickier than lookups, so
     I went for switching them one-by-one.  To do that, a new method
     '->iterate_shared()' is added and filesystems are switched to it
     as they are either confirmed to be OK with shared lock on directory
     or fixed to be OK with that.  I hope to kill the original method
     come next cycle (almost all in-tree filesystems are switched
     already), but it's still not quite finished.

   - several filesystems get switched to parallel readdir.  The
     interesting part here is dealing with dcache preseeding by readdir;
     that needs minor adjustment to be safe with directory locked only
     shared.

     Most of the filesystems doing that got switched to in those
     commits.  Important exception: NFS.  Turns out that NFS folks, with
     their, er, insistence on VFS getting the fuck out of the way of the
     Smart Filesystem Code That Knows How And What To Lock(tm) have
     grown the locking of their own.  They had their own homegrown
     rwsem, with lookup/readdir/atomic_open being *writers* (sillyunlink
     is the reader there).  Of course, with VFS getting the fuck out of
     the way, as requested, the actual smarts of the smart filesystem
     code etc. had become exposed...

   - do_last/lookup_open/atomic_open cleanups.  As the result, open()
     without O_CREAT locks the directory only shared.  Including the
     ->atomic_open() case.  Backmerge from #for-linus in the middle of
     that - atomic_open() fix got brought in.

   - then comes NFS switch to saner (VFS-based ;-) locking, killing the
     homegrown "lookup and readdir are writers" kinda-sorta rwsem.  All
     exclusion for sillyunlink/lookup is done by the parallel lookups
     mechanism.  Exclusion between sillyunlink and rmdir is a real rwsem
     now - rmdir being the writer.

     Result: NFS lookups/readdirs/O_CREAT-less opens happen in parallel
     now.

   - the rest of the series consists of switching a lot of filesystems
     to parallel readdir; in a lot of cases ->llseek() gets simplified
     as well.  One backmerge in there (again, #for-linus - rockridge
     fix)"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (74 commits)
  ext4: switch to ->iterate_shared()
  hfs: switch to ->iterate_shared()
  hfsplus: switch to ->iterate_shared()
  hostfs: switch to ->iterate_shared()
  hpfs: switch to ->iterate_shared()
  hpfs: handle allocation failures in hpfs_add_pos()
  gfs2: switch to ->iterate_shared()
  f2fs: switch to ->iterate_shared()
  afs: switch to ->iterate_shared()
  befs: switch to ->iterate_shared()
  befs: constify stuff a bit
  isofs: switch to ->iterate_shared()
  get_acorn_filename(): deobfuscate a bit
  btrfs: switch to ->iterate_shared()
  logfs: no need to lock directory in lseek
  switch ecryptfs to ->iterate_shared
  9p: switch to ->iterate_shared()
  fat: switch to ->iterate_shared()
  romfs, squashfs: switch to ->iterate_shared()
  more trivial ->iterate_shared conversions
  ...
2016-05-17 11:01:31 -07:00
Al Viro
0e0162bb8c Merge branch 'ovl-fixes' into for-linus
Backmerge to resolve a conflict in ovl_lookup_real();
"ovl_lookup_real(): use lookup_one_len_unlocked()" instead,
but it was too late in the cycle to rebase.
2016-05-17 02:17:59 -04:00
George Spelvin
0fed3ac866 namei: Improve hash mixing if CONFIG_DCACHE_WORD_ACCESS
The hash mixing between adding the next 64 bits of name
was just a bit weak.

Replaced with a still very fast but slightly more effective
mixing function.

Signed-off-by: George Spelvin <linux@horizon.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-16 11:35:08 -07:00
Al Viro
e4d35be584 Merge branch 'ovl-fixes' into for-linus 2016-05-11 00:00:29 -04:00
Miklos Szeredi
3c9fe8cdff vfs: add lookup_hash() helper
Overlayfs needs lookup without inode_permission() and already has the name
hash (in form of dentry->d_name on overlayfs dentry).  It also doesn't
support filesystems with d_op->d_hash() so basically it only needs
the actual hashed lookup from lookup_one_len_unlocked()

So add a new helper that does unlocked lookup of a hashed name.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-05-10 23:56:28 -04:00
Miklos Szeredi
9409e22acd vfs: rename: check backing inode being equal
If a file is renamed to a hardlink of itself POSIX specifies that rename(2)
should do nothing and return success.

This condition is checked in vfs_rename().  However it won't detect hard
links on overlayfs where these are given separate inodes on the overlayfs
layer.

Overlayfs itself detects this condition and returns success without doing
anything, but then vfs_rename() will proceed as if this was a successful
rename (detach_mounts(), d_move()).

The correct thing to do is to detect this condition before even calling
into overlayfs.  This patch does this by calling vfs_select_inode() to get
the underlying inodes.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org> # v4.2+
2016-05-10 23:55:43 -04:00
Al Viro
9cf843e3f4 lookup_open(): lock the parent shared unless O_CREAT is given
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:51:17 -04:00
Al Viro
6fbd07146d lookup_open(): put the dentry fed to ->lookup() or ->atomic_open() into in-lookup hash
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:51:16 -04:00
Al Viro
12fa5e2404 lookup_open(): expand the call of real_lookup()
... and lose the duplicate IS_DEADDIR() - we'd already checked that.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:51:16 -04:00
Al Viro
384f26e28f atomic_open(): reorder and clean up a bit
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:51:15 -04:00
Al Viro
1643b43fbd lookup_open(): lift the "fallback to !O_CREAT" logics from atomic_open()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:51:15 -04:00
Al Viro
b3d58eaffb atomic_open(): be paranoid about may_open() return value
It should never return positives; however, with Linux S&M crowd
involved, no bogosity is impossible.  Results would be unpleasant...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:51:14 -04:00
Al Viro
0fb1ea0933 atomic_open(): delay open_to_namei_flags() until the method call
nobody else needs that transformation.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:51:14 -04:00
Al Viro
fe9ec8291f do_last(): take fput() on error after opening to out:
make it conditional on *opened & FILE_OPENED; in addition to getting
rid of exit_fput: thing, it simplifies atomic_open() cleanup on
may_open() failure.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:51:13 -04:00
Al Viro
47f9dbd387 do_last(): get rid of duplicate ELOOP check
may_open() will catch it

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:51:13 -04:00
Al Viro
55db2fd936 atomic_open(): massage the create_error logics a bit
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:51:12 -04:00
Al Viro
9d0728e16e atomic_open(): consolidate "overridden ENOENT" in open-yourself cases
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:51:12 -04:00
Al Viro
5249e411b4 atomic_open(): don't bother with EEXIST check - it's done in do_last()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:51:11 -04:00
Al Viro
df889b3631 Merge branch 'for-linus' into work.lookups 2016-05-02 19:49:46 -04:00
Al Viro
ce8644fcad lookup_open(): expand the call of vfs_create()
Lift IS_DEADDIR handling up into the part common with atomic_open(),
remove it from the latter.  Collapse permission checks into the
call of may_o_create(), getting it closer to atomic_open() case.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:49:33 -04:00
Al Viro
6ac087099e path_openat(): take O_PATH handling out of do_last()
do_last() and lookup_open() simpler that way and so does O_PATH
itself.  As it bloody well should: we find what the pathname
resolves to, same way as in stat() et.al. and associate it with
FMODE_PATH struct file.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:49:33 -04:00
Al Viro
9902af79c0 parallel lookups: actual switch to rwsem
ta-da!

The main issue is the lack of down_write_killable(), so the places
like readdir.c switched to plain inode_lock(); once killable
variants of rwsem primitives appear, that'll be dealt with.

lockdep side also might need more work

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:49:28 -04:00
Al Viro
d9171b9345 parallel lookups machinery, part 4 (and last)
If we *do* run into an in-lookup match, we need to wait for it to
cease being in-lookup.  Fortunately, we do have unused space in
in-lookup dentries - d_lru is never looked at until it stops being
in-lookup.

So we can stash a pointer to wait_queue_head from stack frame of
the caller of ->lookup().  Some precautions are needed while
waiting, but it's not that hard - we do hold a reference to dentry
we are waiting for, so it can't go away.  If it's found to be
in-lookup the wait_queue_head is still alive and will remain so
at least while ->d_lock is held.  Moreover, the condition we
are waiting for becomes true at the same point where everything
on that wq gets woken up, so we can just add ourselves to the
queue once.

d_alloc_parallel() gets a pointer to wait_queue_head_t from its
caller; lookup_slow() adjusted, d_add_ci() taught to use
d_alloc_parallel() if the dentry passed to it happens to be
in-lookup one (i.e. if it's been called from the parallel lookup).

That's pretty much it - all that remains is to switch ->i_mutex
to rwsem and have lookup_slow() take it shared.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:49:27 -04:00
Al Viro
94bdd655ca parallel lookups machinery, part 3
We will need to be able to check if there is an in-lookup
dentry with matching parent/name.  Right now it's impossible,
but as soon as start locking directories shared such beasts
will appear.

Add a secondary hash for locating those.  Hash chains go through
the same space where d_alias will be once it's not in-lookup anymore.
Search is done under the same bitlock we use for modifications -
with the primary hash we can rely on d_rehash() into the wrong
chain being the worst that could happen, but here the pointers are
buggered once it's removed from the chain.  On the other hand,
the chains are not going to be long and normally we'll end up
adding to the chain anyway.  That allows us to avoid bothering with
->d_lock when doing the comparisons - everything is stable until
removed from chain.

New helper: d_alloc_parallel().  Right now it allocates, verifies
that no hashed and in-lookup matches exist and adds to in-lookup
hash.

Returns ERR_PTR() for error, hashed match (in the unlikely case it's
been found) or new dentry.  In-lookup matches trigger BUG() for
now; that will change in the next commit when we introduce waiting
for ongoing lookup to finish.  Note that in-lookup matches won't be
possible until we actually go for shared locking.

lookup_slow() switched to use of d_alloc_parallel().

Again, these commits are separated only for making it easier to
review.  All this machinery will start doing something useful only
when we go for shared locking; it's just that the combination is
too large for my taste.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:49:27 -04:00
Al Viro
85c7f81041 beginning of transition to parallel lookups - marking in-lookup dentries
marked as such when (would be) parallel lookup is about to pass them
to actual ->lookup(); unmarked when
	* __d_add() is about to make it hashed, positive or not.
	* __d_move() (from d_splice_alias(), directly or via
__d_unalias()) puts a preexisting dentry in its place
	* in caller of ->lookup() if it has escaped all of the
above.  Bug (WARN_ON, actually) if it reaches the final dput()
or d_instantiate() while still marked such.

As the result, we are guaranteed that for as long as the flag is
set, dentry will
	* remain negative unhashed with positive refcount
	* never have its ->d_alias looked at
	* never have its ->d_lru looked at
	* never have its ->d_parent and ->d_name changed

Right now we have at most one such for any given parent directory.
With parallel lookups that restriction will weaken to
	* only exist when parent is locked shared
	* at most one with given (parent,name) pair (comparison of
names is according to ->d_compare())
	* only exist when there's no hashed dentry with the same
(parent,name)

Transition will take the next several commits; unfortunately, we'll
only be able to switch to rwsem at the end of this series.  The
reason for not making it a single patch is to simplify review.

New primitives: d_in_lookup() (a predicate checking if dentry is in
the in-lookup state) and d_lookup_done() (tells the system that
we are done with lookup and if it's still marked as in-lookup, it
should cease to be such).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:47:51 -04:00
Al Viro
1936386ea9 lookup_slow(): bugger off on IS_DEADDIR() from the very beginning
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:47:26 -04:00
Al Viro
84695ffee7 Merge getxattr prototype change into work.lookups
The rest of work.xattr stuff isn't needed for this branch
2016-05-02 19:45:47 -04:00
Mimi Zohar
05d1a717ec ima: add support for creating files using the mknodat syscall
Commit 3034a14 "ima: pass 'opened' flag to identify newly created files"
stopped identifying empty files as new files.  However new empty files
can be created using the mknodat syscall.  On systems with IMA-appraisal
enabled, these empty files are not labeled with security.ima extended
attributes properly, preventing them from subsequently being opened in
order to write the file data contents.  This patch defines a new hook
named ima_post_path_mknod() to mark these empty files, created using
mknodat, as new in order to allow the file data contents to be written.

In addition, files with security.ima xattrs containing a file signature
are considered "immutable" and can not be modified.  The file contents
need to be written, before signing the file.  This patch relaxes this
requirement for new files, allowing the file signature to be written
before the file contents.

Changelog:
- defer identifying files with signatures stored as security.ima
  (based on Dmitry Rozhkov's comments)
- removing tests (eg. dentry, dentry->d_inode, inode->i_size == 0)
  (based on Al's review)

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: Al Viro <<viro@zeniv.linux.org.uk>
Tested-by: Dmitry Rozhkov <dmitry.rozhkov@linux.intel.com>
2016-05-01 09:23:52 -04:00
Al Viro
10c64cea04 atomic_open(): fix the handling of create_error
* if we have a hashed negative dentry and either CREAT|EXCL on
r/o filesystem, or CREAT|TRUNC on r/o filesystem, or CREAT|EXCL
with failing may_o_create(), we should fail with EROFS or the
error may_o_create() has returned, but not ENOENT.  Which is what
the current code ends up returning.

* if we have CREAT|TRUNC hitting a regular file on a read-only
filesystem, we can't fail with EROFS here.  At the very least,
not until we'd done follow_managed() - we might have a writable
file (or a device, for that matter) bound on top of that one.
Moreover, the code downstream will see that O_TRUNC and attempt
to grab the write access (*after* following possible mount), so
if we really should fail with EROFS, it will happen.  No need
to do that inside atomic_open().

The real logics is much simpler than what the current code is
trying to do - if we decided to go for simple lookup, ended
up with a negative dentry *and* had create_error set, fail with
create_error.  No matter whether we'd got that negative dentry
from lookup_real() or had found it in dcache.

Cc: stable@vger.kernel.org # v3.6+
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-04-30 16:40:52 -04:00
Al Viro
fc64005c93 don't bother with ->d_inode->i_sb - it's always equal to ->d_sb
... and neither can ever be NULL

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-04-10 17:11:51 -04:00
Andreas Gruenbacher
b8a7a3a667 posix_acl: Inode acl caching fixes
When get_acl() is called for an inode whose ACL is not cached yet, the
get_acl inode operation is called to fetch the ACL from the filesystem.
The inode operation is responsible for updating the cached acl with
set_cached_acl().  This is done without locking at the VFS level, so
another task can call set_cached_acl() or forget_cached_acl() before the
get_acl inode operation gets to calling set_cached_acl(), and then
get_acl's call to set_cached_acl() results in caching an outdate ACL.

Prevent this from happening by setting the cached ACL pointer to a
task-specific sentinel value before calling the get_acl inode operation.
Move the responsibility for updating the cached ACL from the get_acl
inode operations to get_acl().  There, only set the cached ACL if the
sentinel value hasn't changed.

The sentinel values are chosen to have odd values.  Likewise, the value
of ACL_NOT_CACHED is odd.  In contrast, ACL object pointers always have
an even value (ACLs are aligned in memory).  This allows to distinguish
uncached ACLs values from ACL objects.

In addition, switch from guarding inode->i_acl and inode->i_default_acl
upates by the inode->i_lock spinlock to using xchg() and cmpxchg().

Filesystems that do not want ACLs returned from their get_acl inode
operations to be cached must call forget_cached_acl() to prevent the VFS
from doing so.

(Patch written by Al Viro and Andreas Gruenbacher.)

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-03-31 00:30:15 -04:00
Al Viro
7500c38ac3 fix the braino in "namei: massage lookup_slow() to be usable by lookup_one_len_unlocked()"
We should try to trigger automount *before* bailing out on negative dentry.

Reported-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Reported-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Reported-by: Arend van Spriel <arend@broadcom.com>
Tested-by: Arend van Spriel <arend@broadcom.com>
Tested-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-03-31 00:23:05 -04:00
Al Viro
d360775217 constify security_path_{mkdir,mknod,symlink}
... as well as unix_mknod() and may_o_create()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-03-28 00:47:27 -04:00
Al Viro
9d95afd597 kill dentry_unhash()
the last user is gone

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-03-14 00:16:33 -04:00
Al Viro
949a852e46 namei: teach lookup_slow() to skip revalidate
... and make mountpoint_last() use it.  That makes all
candidates for lookup with parent locked shared go
through lookup_slow().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-03-14 00:15:46 -04:00
Al Viro
e3c1392808 namei: massage lookup_slow() to be usable by lookup_one_len_unlocked()
Return dentry and don't pass nameidata or path; lift crossing mountpoints
into the caller.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-03-14 00:15:40 -04:00
Al Viro
d6d95ded91 lookup_one_len_unlocked(): use lookup_dcache()
No need to lock parent just because of ->d_revalidate() on child;
contrary to the stale comment, lookup_dcache() *can* be used without
locking the parent.  Result can be moved as soon as we return, of
course, but the same is true for lookup_one_len_unlocked() itself.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-03-14 00:15:36 -04:00
Al Viro
74ff0ffc7f namei: simplify invalidation logics in lookup_dcache()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-03-14 00:15:31 -04:00
Al Viro
e9742b5332 namei: change calling conventions for lookup_{fast,slow} and follow_managed()
Have lookup_fast() return 1 on success and 0 on "need to fall back";
lookup_slow() and follow_managed() return positive (1) on success.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-03-14 00:14:35 -04:00
Al Viro
5d0f49c136 namei: untanlge lookup_fast()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-03-14 00:14:25 -04:00
Al Viro
6c51e513a3 lookup_dcache(): lift d_alloc() into callers
... and kill need_lookup thing

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-03-05 20:09:32 -05:00
Al Viro
6583fe22d1 do_last(): reorder and simplify a bit
bugger off on negatives a bit earlier, simplify the tests

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-03-05 18:14:03 -05:00
Al Viro
5129fa482b do_last(): ELOOP failure exit should be done after leaving RCU mode
... or we risk seeing a bogus value of d_is_symlink() there.

Cc: stable@vger.kernel.org # v4.2+
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-02-27 19:37:37 -05:00
Al Viro
a7f775428b should_follow_link(): validate ->d_seq after having decided to follow
... otherwise d_is_symlink() above might have nothing to do with
the inode value we've got.

Cc: stable@vger.kernel.org # v4.2+
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-02-27 19:31:01 -05:00
Al Viro
d4565649b6 namei: ->d_inode of a pinned dentry is stable only for positives
both do_last() and walk_component() risk picking a NULL inode out
of dentry about to become positive, *then* checking its flags and
seeing that it's not negative anymore and using (already stale by
then) value they'd fetched earlier.  Usually ends up oopsing soon
after that...

Cc: stable@vger.kernel.org # v3.13+
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-02-27 19:23:16 -05:00
Al Viro
c80567c82a do_last(): don't let a bogus return value from ->open() et.al. to confuse us
... into returning a positive to path_openat(), which would interpret that
as "symlink had been encountered" and proceed to corrupt memory, etc.
It can only happen due to a bug in some ->open() instance or in some LSM
hook, etc., so we report any such event *and* make sure it doesn't trick
us into further unpleasantness.

Cc: stable@vger.kernel.org # v3.6+, at least
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-02-27 19:17:33 -05:00
Al Viro
5955102c99 wrappers for ->i_mutex access
parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
inode_foo(inode) being mutex_foo(&inode->i_mutex).

Please, use those for access to ->i_mutex; over the coming cycle
->i_mutex will become rwsem, with ->lookup() done with it held
only shared.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-01-22 18:04:28 -05:00
Linus Torvalds
33caf82acf Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull misc vfs updates from Al Viro:
 "All kinds of stuff.  That probably should've been 5 or 6 separate
  branches, but by the time I'd realized how large and mixed that bag
  had become it had been too close to -final to play with rebasing.

  Some fs/namei.c cleanups there, memdup_user_nul() introduction and
  switching open-coded instances, burying long-dead code, whack-a-mole
  of various kinds, several new helpers for ->llseek(), assorted
  cleanups and fixes from various people, etc.

  One piece probably deserves special mention - Neil's
  lookup_one_len_unlocked().  Similar to lookup_one_len(), but gets
  called without ->i_mutex and tries to avoid ever taking it.  That, of
  course, means that it's not useful for any directory modifications,
  but things like getting inode attributes in nfds readdirplus are fine
  with that.  I really should've asked for moratorium on lookup-related
  changes this cycle, but since I hadn't done that early enough...  I
  *am* asking for that for the coming cycle, though - I'm going to try
  and get conversion of i_mutex to rwsem with ->lookup() done under lock
  taken shared.

  There will be a patch closer to the end of the window, along the lines
  of the one Linus had posted last May - mechanical conversion of
  ->i_mutex accesses to inode_lock()/inode_unlock()/inode_trylock()/
  inode_is_locked()/inode_lock_nested().  To quote Linus back then:

    -----
    |    This is an automated patch using
    |
    |        sed 's/mutex_lock(&\(.*\)->i_mutex)/inode_lock(\1)/'
    |        sed 's/mutex_unlock(&\(.*\)->i_mutex)/inode_unlock(\1)/'
    |        sed 's/mutex_lock_nested(&\(.*\)->i_mutex,[     ]*I_MUTEX_\([A-Z0-9_]*\))/inode_lock_nested(\1, I_MUTEX_\2)/'
    |        sed 's/mutex_is_locked(&\(.*\)->i_mutex)/inode_is_locked(\1)/'
    |        sed 's/mutex_trylock(&\(.*\)->i_mutex)/inode_trylock(\1)/'
    |
    |    with a very few manual fixups
    -----

  I'm going to send that once the ->i_mutex-affecting stuff in -next
  gets mostly merged (or when Linus says he's about to stop taking
  merges)"

* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (63 commits)
  nfsd: don't hold i_mutex over userspace upcalls
  fs:affs:Replace time_t with time64_t
  fs/9p: use fscache mutex rather than spinlock
  proc: add a reschedule point in proc_readfd_common()
  logfs: constify logfs_block_ops structures
  fcntl: allow to set O_DIRECT flag on pipe
  fs: __generic_file_splice_read retry lookup on AOP_TRUNCATED_PAGE
  fs: xattr: Use kvfree()
  [s390] page_to_phys() always returns a multiple of PAGE_SIZE
  nbd: use ->compat_ioctl()
  fs: use block_device name vsprintf helper
  lib/vsprintf: add %*pg format specifier
  fs: use gendisk->disk_name where possible
  poll: plug an unused argument to do_poll
  amdkfd: don't open-code memdup_user()
  cdrom: don't open-code memdup_user()
  rsxx: don't open-code memdup_user()
  mtip32xx: don't open-code memdup_user()
  [um] mconsole: don't open-code memdup_user_nul()
  [um] hostaudio: don't open-code memdup_user()
  ...
2016-01-12 17:11:47 -08:00