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Author SHA1 Message Date
Luis Gerhorst
e4f4db4779 bpf: Fix pointer-leak due to insufficient speculative store bypass mitigation 
To mitigate Spectre v4, 2039f26f3a ("bpf: Fix leakage due to
insufficient speculative store bypass mitigation") inserts lfence
instructions after 1) initializing a stack slot and 2) spilling a
pointer to the stack.

However, this does not cover cases where a stack slot is first
initialized with a pointer (subject to sanitization) but then
overwritten with a scalar (not subject to sanitization because
the slot was already initialized). In this case, the second write
may be subject to speculative store bypass (SSB) creating a
speculative pointer-as-scalar type confusion. This allows the
program to subsequently leak the numerical pointer value using,
for example, a branch-based cache side channel.

To fix this, also sanitize scalars if they write a stack slot
that previously contained a pointer. Assuming that pointer-spills
are only generated by LLVM on register-pressure, the performance
impact on most real-world BPF programs should be small.

The following unprivileged BPF bytecode drafts a minimal exploit
and the mitigation:

  [...]
  // r6 = 0 or 1 (skalar, unknown user input)
  // r7 = accessible ptr for side channel
  // r10 = frame pointer (fp), to be leaked
  //
  r9 = r10 # fp alias to encourage ssb
  *(u64 *)(r9 - 8) = r10 // fp[-8] = ptr, to be leaked
  // lfence added here because of pointer spill to stack.
  //
  // Ommitted: Dummy bpf_ringbuf_output() here to train alias predictor
  // for no r9-r10 dependency.
  //
  *(u64 *)(r10 - 8) = r6 // fp[-8] = scalar, overwrites ptr
  // 2039f26f3a: no lfence added because stack slot was not STACK_INVALID,
  // store may be subject to SSB
  //
  // fix: also add an lfence when the slot contained a ptr
  //
  r8 = *(u64 *)(r9 - 8)
  // r8 = architecturally a scalar, speculatively a ptr
  //
  // leak ptr using branch-based cache side channel:
  r8 &= 1 // choose bit to leak
  if r8 == 0 goto SLOW // no mispredict
  // architecturally dead code if input r6 is 0,
  // only executes speculatively iff ptr bit is 1
  r8 = *(u64 *)(r7 + 0) # encode bit in cache (0: slow, 1: fast)
SLOW:
  [...]

After running this, the program can time the access to *(r7 + 0) to
determine whether the chosen pointer bit was 0 or 1. Repeat this 64
times to recover the whole address on amd64.

In summary, sanitization can only be skipped if one scalar is
overwritten with another scalar. Scalar-confusion due to speculative
store bypass can not lead to invalid accesses because the pointer
bounds deducted during verification are enforced using branchless
logic. See 979d63d50c ("bpf: prevent out of bounds speculation on
pointer arithmetic") for details.

Do not make the mitigation depend on !env->allow_{uninit_stack,ptr_leaks}
because speculative leaks are likely unexpected if these were enabled.
For example, leaking the address to a protected log file may be acceptable
while disabling the mitigation might unintentionally leak the address
into the cached-state of a map that is accessible to unprivileged
processes.

Fixes: 2039f26f3a ("bpf: Fix leakage due to insufficient speculative store bypass mitigation")
Signed-off-by: Luis Gerhorst <gerhorst@cs.fau.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Henriette Hofmeier <henriette.hofmeier@rub.de>
Link: https://lore.kernel.org/bpf/edc95bad-aada-9cfc-ffe2-fa9bb206583c@cs.fau.de
Link: https://lore.kernel.org/bpf/20230109150544.41465-1-gerhorst@cs.fau.de
 2023-01-13 17:18:35 +01:00
Tonghao Zhang
9f907439dc bpf: hash map, avoid deadlock with suitable hash mask 
The deadlock still may occur while accessed in NMI and non-NMI
context. Because in NMI, we still may access the same bucket but with
different map_locked index.

For example, on the same CPU, .max_entries = 2, we update the hash map,
with key = 4, while running bpf prog in NMI nmi_handle(), to update
hash map with key = 20, so it will have the same bucket index but have
different map_locked index.

To fix this issue, using min mask to hash again.

Fixes: 20b6cc34ea ("bpf: Avoid hashtab deadlock with map_locked")
Signed-off-by: Tonghao Zhang <tong@infragraf.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Song Liu <song@kernel.org>
Cc: Yonghong Song <yhs@fb.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20230111092903.92389-1-tong@infragraf.org
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
 2023-01-12 18:55:42 -08:00
Paul Moore
e7895f017b bpf: remove the do_idr_lock parameter from bpf_prog_free_id() 
It was determined that the do_idr_lock parameter to
bpf_prog_free_id() was not necessary as it should always be true.

Suggested-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20230106154400.74211-2-paul@paul-moore.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2023-01-09 19:47:59 -08:00
Paul Moore
ef01f4e25c bpf: restore the ebpf program ID for BPF_AUDIT_UNLOAD and PERF_BPF_EVENT_PROG_UNLOAD 
When changing the ebpf program put() routines to support being called
from within IRQ context the program ID was reset to zero prior to
calling the perf event and audit UNLOAD record generators, which
resulted in problems as the ebpf program ID was bogus (always zero).
This patch addresses this problem by removing an unnecessary call to
bpf_prog_free_id() in __bpf_prog_offload_destroy() and adjusting
__bpf_prog_put() to only call bpf_prog_free_id() after audit and perf
have finished their bpf program unload tasks in
bpf_prog_put_deferred().  For the record, no one can determine, or
remember, why it was necessary to free the program ID, and remove it
from the IDR, prior to executing bpf_prog_put_deferred();
regardless, both Stanislav and Alexei agree that the approach in this
patch should be safe.

It is worth noting that when moving the bpf_prog_free_id() call, the
do_idr_lock parameter was forced to true as the ebpf devs determined
this was the correct as the do_idr_lock should always be true.  The
do_idr_lock parameter will be removed in a follow-up patch, but it
was kept here to keep the patch small in an effort to ease any stable
backports.

I also modified the bpf_audit_prog() logic used to associate the
AUDIT_BPF record with other associated records, e.g. @ctx != NULL.
Instead of keying off the operation, it now keys off the execution
context, e.g. '!in_irg && !irqs_disabled()', which is much more
appropriate and should help better connect the UNLOAD operations with
the associated audit state (other audit records).

Cc: stable@vger.kernel.org
Fixes: d809e134be ("bpf: Prepare bpf_prog_put() to be called from irq context.")
Reported-by: Burn Alting <burn.alting@iinet.net.au>
Reported-by: Jiri Olsa <olsajiri@gmail.com>
Suggested-by: Stanislav Fomichev <sdf@google.com>
Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20230106154400.74211-1-paul@paul-moore.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2023-01-09 19:47:58 -08:00
Hao Sun
d3178e8a43 bpf: Skip invalid kfunc call in backtrack_insn 
The verifier skips invalid kfunc call in check_kfunc_call(), which
would be captured in fixup_kfunc_call() if such insn is not eliminated
by dead code elimination. However, this can lead to the following
warning in backtrack_insn(), also see [1]:

  ------------[ cut here ]------------
  verifier backtracking bug
  WARNING: CPU: 6 PID: 8646 at kernel/bpf/verifier.c:2756 backtrack_insn
  kernel/bpf/verifier.c:2756
	__mark_chain_precision kernel/bpf/verifier.c:3065
	mark_chain_precision kernel/bpf/verifier.c:3165
	adjust_reg_min_max_vals kernel/bpf/verifier.c:10715
	check_alu_op kernel/bpf/verifier.c:10928
	do_check kernel/bpf/verifier.c:13821 [inline]
	do_check_common kernel/bpf/verifier.c:16289
  [...]

So make backtracking conservative with this by returning ENOTSUPP.

  [1] https://lore.kernel.org/bpf/CACkBjsaXNceR8ZjkLG=dT3P=4A8SBsg0Z5h5PWLryF5=ghKq=g@mail.gmail.com/

Reported-by: syzbot+4da3ff23081bafe74fc2@syzkaller.appspotmail.com
Signed-off-by: Hao Sun <sunhao.th@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20230104014709.9375-1-sunhao.th@gmail.com
 2023-01-06 18:49:37 +01:00
Kees Cook
45435d8da7 bpf: Always use maximal size for copy_array() 
Instead of counting on prior allocations to have sized allocations to
the next kmalloc bucket size, always perform a krealloc that is at least
ksize(dst) in size (which is a no-op), so the size can be correctly
tracked by all the various allocation size trackers (KASAN,
__alloc_size, etc).

Reported-by: Hyunwoo Kim <v4bel@theori.io>
Link: https://lore.kernel.org/bpf/20221223094551.GA1439509@ubuntu
Fixes: ceb35b666d ("bpf/verifier: Use kmalloc_size_roundup() to match ksize() usage")
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Song Liu <song@kernel.org>
Cc: Yonghong Song <yhs@fb.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: bpf@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20221223182836.never.866-kees@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-28 14:54:53 -08:00
Kui-Feng Lee
7ff94f276f bpf: keep a reference to the mm, in case the task is dead. 
Fix the system crash that happens when a task iterator travel through
vma of tasks.

In task iterators, we used to access mm by following the pointer on
the task_struct; however, the death of a task will clear the pointer,
even though we still hold the task_struct.  That can cause an
unexpected crash for a null pointer when an iterator is visiting a
task that dies during the visit.  Keeping a reference of mm on the
iterator ensures we always have a valid pointer to mm.

Co-developed-by: Song Liu <song@kernel.org>
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Kui-Feng Lee <kuifeng@meta.com>
Reported-by: Nathan Slingerland <slinger@meta.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221216221855.4122288-2-kuifeng@meta.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-28 14:11:48 -08:00
Chuang Wang
9ed1d9aeef bpf: Fix panic due to wrong pageattr of im->image 
In the scenario where livepatch and kretfunc coexist, the pageattr of
im->image is rox after arch_prepare_bpf_trampoline in
bpf_trampoline_update, and then modify_fentry or register_fentry returns
-EAGAIN from bpf_tramp_ftrace_ops_func, the BPF_TRAMP_F_ORIG_STACK flag
will be configured, and arch_prepare_bpf_trampoline will be re-executed.

At this time, because the pageattr of im->image is rox,
arch_prepare_bpf_trampoline will read and write im->image, which causes
a fault. as follows:

  insmod livepatch-sample.ko    # samples/livepatch/livepatch-sample.c
  bpftrace -e 'kretfunc:cmdline_proc_show {}'

BUG: unable to handle page fault for address: ffffffffa0206000
PGD 322d067 P4D 322d067 PUD 322e063 PMD 1297e067 PTE d428061
Oops: 0003 [#1] PREEMPT SMP PTI
CPU: 2 PID: 270 Comm: bpftrace Tainted: G            E K    6.1.0 #5
RIP: 0010:arch_prepare_bpf_trampoline+0xed/0x8c0
RSP: 0018:ffffc90001083ad8 EFLAGS: 00010202
RAX: ffffffffa0206000 RBX: 0000000000000020 RCX: 0000000000000000
RDX: ffffffffa0206001 RSI: ffffffffa0206000 RDI: 0000000000000030
RBP: ffffc90001083b70 R08: 0000000000000066 R09: ffff88800f51b400
R10: 000000002e72c6e5 R11: 00000000d0a15080 R12: ffff8880110a68c8
R13: 0000000000000000 R14: ffff88800f51b400 R15: ffffffff814fec10
FS:  00007f87bc0dc780(0000) GS:ffff88803e600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffa0206000 CR3: 0000000010b70000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
 bpf_trampoline_update+0x25a/0x6b0
 __bpf_trampoline_link_prog+0x101/0x240
 bpf_trampoline_link_prog+0x2d/0x50
 bpf_tracing_prog_attach+0x24c/0x530
 bpf_raw_tp_link_attach+0x73/0x1d0
 __sys_bpf+0x100e/0x2570
 __x64_sys_bpf+0x1c/0x30
 do_syscall_64+0x5b/0x80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

With this patch, when modify_fentry or register_fentry returns -EAGAIN
from bpf_tramp_ftrace_ops_func, the pageattr of im->image will be reset
to nx+rw.

Cc: stable@vger.kernel.org
Fixes: 00963a2e75 ("bpf: Support bpf_trampoline on functions with IPMODIFY (e.g. livepatch)")
Signed-off-by: Chuang Wang <nashuiliang@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20221224133146.780578-1-nashuiliang@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-28 13:46:28 -08:00
David S. Miller
be1236fce5 bpf-for-netdev 
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Merge tag 'for-netdev' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Daniel Borkmann says:

====================
The following pull-request contains BPF updates for your *net* tree.

We've added 7 non-merge commits during the last 5 day(s) which contain
a total of 11 files changed, 231 insertions(+), 3 deletions(-).

The main changes are:

1) Fix a splat in bpf_skb_generic_pop() under CHECKSUM_PARTIAL due to
   misuse of skb_postpull_rcsum(), from Jakub Kicinski with test case
   from Martin Lau.

2) Fix BPF verifier's nullness propagation when registers are of
   type PTR_TO_BTF_ID, from Hao Sun.

3) Fix bpftool build for JIT disassembler under statically built
   libllvm, from Anton Protopopov.

4) Fix warnings reported by resolve_btfids when building vmlinux
   with CONFIG_SECURITY_NETWORK disabled, from Hou Tao.

5) Minor fix up for BPF selftest gitignore, from Stanislav Fomichev.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
 2022-12-24 09:39:02 +00:00
Hao Sun
8374bfd5a3 bpf: fix nullness propagation for reg to reg comparisons 
After befae75856, the verifier would propagate null information after
JEQ/JNE, e.g., if two pointers, one is maybe_null and the other is not,
the former would be marked as non-null in eq path. However, as comment
"PTR_TO_BTF_ID points to a kernel struct that does not need to be null
checked by the BPF program ... The verifier must keep this in mind and
can make no assumptions about null or non-null when doing branch ...".
If one pointer is maybe_null and the other is PTR_TO_BTF, the former is
incorrectly marked non-null. The following BPF prog can trigger a
null-ptr-deref, also see this report for more details[1]:

	0: (18) r1 = map_fd	        ; R1_w=map_ptr(ks=4, vs=4)
	2: (79) r6 = *(u64 *)(r1 +8)    ; R6_w=bpf_map->inner_map_data
					; R6 is PTR_TO_BTF_ID
					; equals to null at runtime
	3: (bf) r2 = r10
	4: (07) r2 += -4
	5: (62) *(u32 *)(r2 +0) = 0
	6: (85) call bpf_map_lookup_elem#1    ; R0_w=map_value_or_null
	7: (1d) if r6 == r0 goto pc+1
	8: (95) exit
	; from 7 to 9: R0=map_value R6=ptr_bpf_map
	9: (61) r0 = *(u32 *)(r0 +0)          ; null-ptr-deref
	10: (95) exit

So, make the verifier propagate nullness information for reg to reg
comparisons only if neither reg is PTR_TO_BTF_ID.

[1] https://lore.kernel.org/bpf/CACkBjsaFJwjC5oiw-1KXvcazywodwXo4zGYsRHwbr2gSG9WcSw@mail.gmail.com/T/#u

Fixes: befae75856 ("bpf: propagate nullness information for reg to reg comparisons")
Signed-off-by: Hao Sun <sunhao.th@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221222024414.29539-1-sunhao.th@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
 2022-12-22 17:19:06 -08:00
Linus Torvalds
609d3bc623 Including fixes from bpf, netfilter and can. 
Current release - regressions:
 
  - bpf: synchronize dispatcher update with bpf_dispatcher_xdp_func
 
  - rxrpc:
   - fix security setting propagation
   - fix null-deref in rxrpc_unuse_local()
   - fix switched parameters in peer tracing
 
 Current release - new code bugs:
 
  - rxrpc:
    - fix I/O thread startup getting skipped
    - fix locking issues in rxrpc_put_peer_locked()
    - fix I/O thread stop
    - fix uninitialised variable in rxperf server
    - fix the return value of rxrpc_new_incoming_call()
 
  - microchip: vcap: fix initialization of value and mask
 
  - nfp: fix unaligned io read of capabilities word
 
 Previous releases - regressions:
 
  - stop in-kernel socket users from corrupting socket's task_frag
 
  - stream: purge sk_error_queue in sk_stream_kill_queues()
 
  - openvswitch: fix flow lookup to use unmasked key
 
  - dsa: mv88e6xxx: avoid reg_lock deadlock in mv88e6xxx_setup_port()
 
  - devlink:
    - hold region lock when flushing snapshots
    - protect devlink dump by the instance lock
 
 Previous releases - always broken:
 
  - bpf:
    - prevent leak of lsm program after failed attach
    - resolve fext program type when checking map compatibility
 
  - skbuff: account for tail adjustment during pull operations
 
  - macsec: fix net device access prior to holding a lock
 
  - bonding: switch back when high prio link up
 
  - netfilter: flowtable: really fix NAT IPv6 offload
 
  - enetc: avoid buffer leaks on xdp_do_redirect() failure
 
  - unix: fix race in SOCK_SEQPACKET's unix_dgram_sendmsg()
 
  - dsa: microchip: remove IRQF_TRIGGER_FALLING in request_threaded_irq
 
 Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Merge tag 'net-6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

Pull networking fixes from Jakub Kicinski:
 "Including fixes from bpf, netfilter and can.

  Current release - regressions:

   - bpf: synchronize dispatcher update with bpf_dispatcher_xdp_func

   - rxrpc:
      - fix security setting propagation
      - fix null-deref in rxrpc_unuse_local()
      - fix switched parameters in peer tracing

  Current release - new code bugs:

   - rxrpc:
      - fix I/O thread startup getting skipped
      - fix locking issues in rxrpc_put_peer_locked()
      - fix I/O thread stop
      - fix uninitialised variable in rxperf server
      - fix the return value of rxrpc_new_incoming_call()

   - microchip: vcap: fix initialization of value and mask

   - nfp: fix unaligned io read of capabilities word

  Previous releases - regressions:

   - stop in-kernel socket users from corrupting socket's task_frag

   - stream: purge sk_error_queue in sk_stream_kill_queues()

   - openvswitch: fix flow lookup to use unmasked key

   - dsa: mv88e6xxx: avoid reg_lock deadlock in mv88e6xxx_setup_port()

   - devlink:
      - hold region lock when flushing snapshots
      - protect devlink dump by the instance lock

  Previous releases - always broken:

   - bpf:
      - prevent leak of lsm program after failed attach
      - resolve fext program type when checking map compatibility

   - skbuff: account for tail adjustment during pull operations

   - macsec: fix net device access prior to holding a lock

   - bonding: switch back when high prio link up

   - netfilter: flowtable: really fix NAT IPv6 offload

   - enetc: avoid buffer leaks on xdp_do_redirect() failure

   - unix: fix race in SOCK_SEQPACKET's unix_dgram_sendmsg()

   - dsa: microchip: remove IRQF_TRIGGER_FALLING in
     request_threaded_irq"

* tag 'net-6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (64 commits)
  net: fec: check the return value of build_skb()
  net: simplify sk_page_frag
  Treewide: Stop corrupting socket's task_frag
  net: Introduce sk_use_task_frag in struct sock.
  mctp: Remove device type check at unregister
  net: dsa: microchip: remove IRQF_TRIGGER_FALLING in request_threaded_irq
  can: kvaser_usb: hydra: help gcc-13 to figure out cmd_len
  can: flexcan: avoid unbalanced pm_runtime_enable warning
  Documentation: devlink: add missing toc entry for etas_es58x devlink doc
  mctp: serial: Fix starting value for frame check sequence
  nfp: fix unaligned io read of capabilities word
  net: stream: purge sk_error_queue in sk_stream_kill_queues()
  myri10ge: Fix an error handling path in myri10ge_probe()
  net: microchip: vcap: Fix initialization of value and mask
  rxrpc: Fix the return value of rxrpc_new_incoming_call()
  rxrpc: rxperf: Fix uninitialised variable
  rxrpc: Fix I/O thread stop
  rxrpc: Fix switched parameters in peer tracing
  rxrpc: Fix locking issues in rxrpc_put_peer_locked()
  rxrpc: Fix I/O thread startup getting skipped
  ...
 2022-12-21 08:41:32 -08:00
Hou Tao
cc07482246 bpf: Define sock security related BTF IDs under CONFIG_SECURITY_NETWORK 
There are warnings reported from resolve_btfids when building vmlinux
with CONFIG_SECURITY_NETWORK disabled:

  WARN: resolve_btfids: unresolved symbol bpf_lsm_sk_free_security
  WARN: resolve_btfids: unresolved symbol bpf_lsm_sk_alloc_security

So only define BTF IDs for these LSM hooks when CONFIG_SECURITY_NETWORK
is enabled.

Fixes: c0c852dd18 ("bpf: Do not mark certain LSM hook arguments as trusted")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20221217062144.2507222-1-houtao@huaweicloud.com
 2022-12-19 22:02:17 +01:00
Linus Torvalds
4f292c4de4 New Feature: 
* Randomize the per-cpu entry areas
 Cleanups:
 * Have CR3_ADDR_MASK use PHYSICAL_PAGE_MASK instead of open
   coding it
 * Move to "native" set_memory_rox() helper
 * Clean up pmd_get_atomic() and i386-PAE
 * Remove some unused page table size macros
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Merge tag 'x86_mm_for_6.2_v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 mm updates from Dave Hansen:
 "New Feature:

   - Randomize the per-cpu entry areas

  Cleanups:

   - Have CR3_ADDR_MASK use PHYSICAL_PAGE_MASK instead of open coding it

   - Move to "native" set_memory_rox() helper

   - Clean up pmd_get_atomic() and i386-PAE

   - Remove some unused page table size macros"

* tag 'x86_mm_for_6.2_v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (35 commits)
  x86/mm: Ensure forced page table splitting
  x86/kasan: Populate shadow for shared chunk of the CPU entry area
  x86/kasan: Add helpers to align shadow addresses up and down
  x86/kasan: Rename local CPU_ENTRY_AREA variables to shorten names
  x86/mm: Populate KASAN shadow for entire per-CPU range of CPU entry area
  x86/mm: Recompute physical address for every page of per-CPU CEA mapping
  x86/mm: Rename __change_page_attr_set_clr(.checkalias)
  x86/mm: Inhibit _PAGE_NX changes from cpa_process_alias()
  x86/mm: Untangle __change_page_attr_set_clr(.checkalias)
  x86/mm: Add a few comments
  x86/mm: Fix CR3_ADDR_MASK
  x86/mm: Remove P*D_PAGE_MASK and P*D_PAGE_SIZE macros
  mm: Convert __HAVE_ARCH_P..P_GET to the new style
  mm: Remove pointless barrier() after pmdp_get_lockless()
  x86/mm/pae: Get rid of set_64bit()
  x86_64: Remove pointless set_64bit() usage
  x86/mm/pae: Be consistent with pXXp_get_and_clear()
  x86/mm/pae: Use WRITE_ONCE()
  x86/mm/pae: Don't (ab)use atomic64
  mm/gup: Fix the lockless PMD access
  ...
 2022-12-17 14:06:53 -06:00
Peter Zijlstra
d48567c9a0 mm: Introduce set_memory_rox() 
Because endlessly repeating:

	set_memory_ro()
	set_memory_x()

is getting tedious.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/Y1jek64pXOsougmz@hirez.programming.kicks-ass.net
 2022-12-15 10:37:26 -08:00
Toke Høiland-Jørgensen
1c123c567f bpf: Resolve fext program type when checking map compatibility 
The bpf_prog_map_compatible() check makes sure that BPF program types are
not mixed inside BPF map types that can contain programs (tail call maps,
cpumaps and devmaps). It does this by setting the fields of the map->owner
struct to the values of the first program being checked against, and
rejecting any subsequent programs if the values don't match.

One of the values being set in the map owner struct is the program type,
and since the code did not resolve the prog type for fext programs, the map
owner type would be set to PROG_TYPE_EXT and subsequent loading of programs
of the target type into the map would fail.

This bug is seen in particular for XDP programs that are loaded as
PROG_TYPE_EXT using libxdp; these cannot insert programs into devmaps and
cpumaps because the check fails as described above.

Fix the bug by resolving the fext program type to its target program type
as elsewhere in the verifier.

v3:
- Add Yonghong's ACK

Fixes: f45d5b6ce2 ("bpf: generalise tail call map compatibility check")
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20221214230254.790066-1-toke@redhat.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
 2022-12-14 21:30:27 -08:00
Jiri Olsa
4121d4481b bpf: Synchronize dispatcher update with bpf_dispatcher_xdp_func 
Hao Sun reported crash in dispatcher image [1].

Currently we don't have any sync between bpf_dispatcher_update and
bpf_dispatcher_xdp_func, so following race is possible:

 cpu 0:                               cpu 1:

 bpf_prog_run_xdp
   ...
   bpf_dispatcher_xdp_func
     in image at offset 0x0

                                      bpf_dispatcher_update
                                        update image at offset 0x800
                                      bpf_dispatcher_update
                                        update image at offset 0x0

     in image at offset 0x0 -> crash

Fixing this by synchronizing dispatcher image update (which is done
in bpf_dispatcher_update function) with bpf_dispatcher_xdp_func that
reads and execute the dispatcher image.

Calling synchronize_rcu after updating and installing new image ensures
that readers leave old image before it's changed in the next dispatcher
update. The update itself is locked with dispatcher's mutex.

The bpf_prog_run_xdp is called under local_bh_disable and synchronize_rcu
will wait for it to leave [2].

[1] https://lore.kernel.org/bpf/Y5SFho7ZYXr9ifRn@krava/T/#m00c29ece654bc9f332a17df493bbca33e702896c
[2] https://lore.kernel.org/bpf/0B62D35A-E695-4B7A-A0D4-774767544C1A@gmail.com/T/#mff43e2c003ae99f4a38f353c7969be4c7162e877

Reported-by: Hao Sun <sunhao.th@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/r/20221214123542.1389719-1-jolsa@kernel.org
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
 2022-12-14 12:02:14 -08:00
Milan Landaverde
e89f3edffb bpf: prevent leak of lsm program after failed attach 
In [0], we added the ability to bpf_prog_attach LSM programs to cgroups,
but in our validation to make sure the prog is meant to be attached to
BPF_LSM_CGROUP, we return too early if the check fails. This results in
lack of decrementing prog's refcnt (through bpf_prog_put)
leaving the LSM program alive past the point of the expected lifecycle.
This fix allows for the decrement to take place.

[0] https://lore.kernel.org/all/20220628174314.1216643-4-sdf@google.com/

Fixes: 69fd337a97 ("bpf: per-cgroup lsm flavor")
Signed-off-by: Milan Landaverde <milan@mdaverde.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20221213175714.31963-1-milan@mdaverde.com
 2022-12-14 18:35:41 +01:00
Linus Torvalds
7e68dd7d07 Networking changes for 6.2. 
Core
 ----
  - Allow live renaming when an interface is up
 
  - Add retpoline wrappers for tc, improving considerably the
    performances of complex queue discipline configurations.
 
  - Add inet drop monitor support.
 
  - A few GRO performance improvements.
 
  - Add infrastructure for atomic dev stats, addressing long standing
    data races.
 
  - De-duplicate common code between OVS and conntrack offloading
    infrastructure.
 
  - A bunch of UBSAN_BOUNDS/FORTIFY_SOURCE improvements.
 
  - Netfilter: introduce packet parser for tunneled packets
 
  - Replace IPVS timer-based estimators with kthreads to scale up
    the workload with the number of available CPUs.
 
  - Add the helper support for connection-tracking OVS offload.
 
 BPF
 ---
  - Support for user defined BPF objects: the use case is to allocate
    own objects, build own object hierarchies and use the building
    blocks to build own data structures flexibly, for example, linked
    lists in BPF.
 
  - Make cgroup local storage available to non-cgroup attached BPF
    programs.
 
  - Avoid unnecessary deadlock detection and failures wrt BPF task
    storage helpers.
 
  - A relevant bunch of BPF verifier fixes and improvements.
 
  - Veristat tool improvements to support custom filtering, sorting,
    and replay of results.
 
  - Add LLVM disassembler as default library for dumping JITed code.
 
  - Lots of new BPF documentation for various BPF maps.
 
  - Add bpf_rcu_read_{,un}lock() support for sleepable programs.
 
  - Add RCU grace period chaining to BPF to wait for the completion
    of access from both sleepable and non-sleepable BPF programs.
 
  - Add support storing struct task_struct objects as kptrs in maps.
 
  - Improve helper UAPI by explicitly defining BPF_FUNC_xxx integer
    values.
 
  - Add libbpf *_opts API-variants for bpf_*_get_fd_by_id() functions.
 
 Protocols
 ---------
  - TCP: implement Protective Load Balancing across switch links.
 
  - TCP: allow dynamically disabling TCP-MD5 static key, reverting
    back to fast[er]-path.
 
  - UDP: Introduce optional per-netns hash lookup table.
 
  - IPv6: simplify and cleanup sockets disposal.
 
  - Netlink: support different type policies for each generic
    netlink operation.
 
  - MPTCP: add MSG_FASTOPEN and FastOpen listener side support.
 
  - MPTCP: add netlink notification support for listener sockets
    events.
 
  - SCTP: add VRF support, allowing sctp sockets binding to VRF
    devices.
 
  - Add bridging MAC Authentication Bypass (MAB) support.
 
  - Extensions for Ethernet VPN bridging implementation to better
    support multicast scenarios.
 
  - More work for Wi-Fi 7 support, comprising conversion of all
    the existing drivers to internal TX queue usage.
 
  - IPSec: introduce a new offload type (packet offload) allowing
    complete header processing and crypto offloading.
 
  - IPSec: extended ack support for more descriptive XFRM error
    reporting.
 
  - RXRPC: increase SACK table size and move processing into a
    per-local endpoint kernel thread, reducing considerably the
    required locking.
 
  - IEEE 802154: synchronous send frame and extended filtering
    support, initial support for scanning available 15.4 networks.
 
  - Tun: bump the link speed from 10Mbps to 10Gbps.
 
  - Tun/VirtioNet: implement UDP segmentation offload support.
 
 Driver API
 ----------
 
  - PHY/SFP: improve power level switching between standard
    level 1 and the higher power levels.
 
  - New API for netdev <-> devlink_port linkage.
 
  - PTP: convert existing drivers to new frequency adjustment
    implementation.
 
  - DSA: add support for rx offloading.
 
  - Autoload DSA tagging driver when dynamically changing protocol.
 
  - Add new PCP and APPTRUST attributes to Data Center Bridging.
 
  - Add configuration support for 800Gbps link speed.
 
  - Add devlink port function attribute to enable/disable RoCE and
    migratable.
 
  - Extend devlink-rate to support strict prioriry and weighted fair
    queuing.
 
  - Add devlink support to directly reading from region memory.
 
  - New device tree helper to fetch MAC address from nvmem.
 
  - New big TCP helper to simplify temporary header stripping.
 
 New hardware / drivers
 ----------------------
 
  - Ethernet:
    - Marvel Octeon CNF95N and CN10KB Ethernet Switches.
    - Marvel Prestera AC5X Ethernet Switch.
    - WangXun 10 Gigabit NIC.
    - Motorcomm yt8521 Gigabit Ethernet.
    - Microchip ksz9563 Gigabit Ethernet Switch.
    - Microsoft Azure Network Adapter.
    - Linux Automation 10Base-T1L adapter.
 
  - PHY:
    - Aquantia AQR112 and AQR412.
    - Motorcomm YT8531S.
 
  - PTP:
    - Orolia ART-CARD.
 
  - WiFi:
    - MediaTek Wi-Fi 7 (802.11be) devices.
    - RealTek rtw8821cu, rtw8822bu, rtw8822cu and rtw8723du USB
      devices.
 
  - Bluetooth:
    - Broadcom BCM4377/4378/4387 Bluetooth chipsets.
    - Realtek RTL8852BE and RTL8723DS.
    - Cypress.CYW4373A0 WiFi + Bluetooth combo device.
 
 Drivers
 -------
  - CAN:
    - gs_usb: bus error reporting support.
    - kvaser_usb: listen only and bus error reporting support.
 
  - Ethernet NICs:
    - Intel (100G):
      - extend action skbedit to RX queue mapping.
      - implement devlink-rate support.
      - support direct read from memory.
    - nVidia/Mellanox (mlx5):
      - SW steering improvements, increasing rules update rate.
      - Support for enhanced events compression.
      - extend H/W offload packet manipulation capabilities.
      - implement IPSec packet offload mode.
    - nVidia/Mellanox (mlx4):
      - better big TCP support.
    - Netronome Ethernet NICs (nfp):
      - IPsec offload support.
      - add support for multicast filter.
    - Broadcom:
      - RSS and PTP support improvements.
    - AMD/SolarFlare:
      - netlink extened ack improvements.
      - add basic flower matches to offload, and related stats.
    - Virtual NICs:
      - ibmvnic: introduce affinity hint support.
    - small / embedded:
      - FreeScale fec: add initial XDP support.
      - Marvel mv643xx_eth: support MII/GMII/RGMII modes for Kirkwood.
      - TI am65-cpsw: add suspend/resume support.
      - Mediatek MT7986: add RX wireless wthernet dispatch support.
      - Realtek 8169: enable GRO software interrupt coalescing per
        default.
 
  - Ethernet high-speed switches:
    - Microchip (sparx5):
      - add support for Sparx5 TC/flower H/W offload via VCAP.
    - Mellanox mlxsw:
      - add 802.1X and MAC Authentication Bypass offload support.
      - add ip6gre support.
 
  - Embedded Ethernet switches:
    - Mediatek (mtk_eth_soc):
      - improve PCS implementation, add DSA untag support.
      - enable flow offload support.
    - Renesas:
      - add rswitch R-Car Gen4 gPTP support.
    - Microchip (lan966x):
      - add full XDP support.
      - add TC H/W offload via VCAP.
      - enable PTP on bridge interfaces.
    - Microchip (ksz8):
      - add MTU support for KSZ8 series.
 
  - Qualcomm 802.11ax WiFi (ath11k):
    - support configuring channel dwell time during scan.
 
  - MediaTek WiFi (mt76):
    - enable Wireless Ethernet Dispatch (WED) offload support.
    - add ack signal support.
    - enable coredump support.
    - remain_on_channel support.
 
  - Intel WiFi (iwlwifi):
    - enable Wi-Fi 7 Extremely High Throughput (EHT) PHY capabilities.
    - 320 MHz channels support.
 
  - RealTek WiFi (rtw89):
    - new dynamic header firmware format support.
    - wake-over-WLAN support.
 
 Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Merge tag 'net-next-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next

Pull networking updates from Paolo Abeni:
 "Core:

   - Allow live renaming when an interface is up

   - Add retpoline wrappers for tc, improving considerably the
     performances of complex queue discipline configurations

   - Add inet drop monitor support

   - A few GRO performance improvements

   - Add infrastructure for atomic dev stats, addressing long standing
     data races

   - De-duplicate common code between OVS and conntrack offloading
     infrastructure

   - A bunch of UBSAN_BOUNDS/FORTIFY_SOURCE improvements

   - Netfilter: introduce packet parser for tunneled packets

   - Replace IPVS timer-based estimators with kthreads to scale up the
     workload with the number of available CPUs

   - Add the helper support for connection-tracking OVS offload

  BPF:

   - Support for user defined BPF objects: the use case is to allocate
     own objects, build own object hierarchies and use the building
     blocks to build own data structures flexibly, for example, linked
     lists in BPF

   - Make cgroup local storage available to non-cgroup attached BPF
     programs

   - Avoid unnecessary deadlock detection and failures wrt BPF task
     storage helpers

   - A relevant bunch of BPF verifier fixes and improvements

   - Veristat tool improvements to support custom filtering, sorting,
     and replay of results

   - Add LLVM disassembler as default library for dumping JITed code

   - Lots of new BPF documentation for various BPF maps

   - Add bpf_rcu_read_{,un}lock() support for sleepable programs

   - Add RCU grace period chaining to BPF to wait for the completion of
     access from both sleepable and non-sleepable BPF programs

   - Add support storing struct task_struct objects as kptrs in maps

   - Improve helper UAPI by explicitly defining BPF_FUNC_xxx integer
     values

   - Add libbpf *_opts API-variants for bpf_*_get_fd_by_id() functions

  Protocols:

   - TCP: implement Protective Load Balancing across switch links

   - TCP: allow dynamically disabling TCP-MD5 static key, reverting back
     to fast[er]-path

   - UDP: Introduce optional per-netns hash lookup table

   - IPv6: simplify and cleanup sockets disposal

   - Netlink: support different type policies for each generic netlink
     operation

   - MPTCP: add MSG_FASTOPEN and FastOpen listener side support

   - MPTCP: add netlink notification support for listener sockets events

   - SCTP: add VRF support, allowing sctp sockets binding to VRF devices

   - Add bridging MAC Authentication Bypass (MAB) support

   - Extensions for Ethernet VPN bridging implementation to better
     support multicast scenarios

   - More work for Wi-Fi 7 support, comprising conversion of all the
     existing drivers to internal TX queue usage

   - IPSec: introduce a new offload type (packet offload) allowing
     complete header processing and crypto offloading

   - IPSec: extended ack support for more descriptive XFRM error
     reporting

   - RXRPC: increase SACK table size and move processing into a
     per-local endpoint kernel thread, reducing considerably the
     required locking

   - IEEE 802154: synchronous send frame and extended filtering support,
     initial support for scanning available 15.4 networks

   - Tun: bump the link speed from 10Mbps to 10Gbps

   - Tun/VirtioNet: implement UDP segmentation offload support

  Driver API:

   - PHY/SFP: improve power level switching between standard level 1 and
     the higher power levels

   - New API for netdev <-> devlink_port linkage

   - PTP: convert existing drivers to new frequency adjustment
     implementation

   - DSA: add support for rx offloading

   - Autoload DSA tagging driver when dynamically changing protocol

   - Add new PCP and APPTRUST attributes to Data Center Bridging

   - Add configuration support for 800Gbps link speed

   - Add devlink port function attribute to enable/disable RoCE and
     migratable

   - Extend devlink-rate to support strict prioriry and weighted fair
     queuing

   - Add devlink support to directly reading from region memory

   - New device tree helper to fetch MAC address from nvmem

   - New big TCP helper to simplify temporary header stripping

  New hardware / drivers:

   - Ethernet:
      - Marvel Octeon CNF95N and CN10KB Ethernet Switches
      - Marvel Prestera AC5X Ethernet Switch
      - WangXun 10 Gigabit NIC
      - Motorcomm yt8521 Gigabit Ethernet
      - Microchip ksz9563 Gigabit Ethernet Switch
      - Microsoft Azure Network Adapter
      - Linux Automation 10Base-T1L adapter

   - PHY:
      - Aquantia AQR112 and AQR412
      - Motorcomm YT8531S

   - PTP:
      - Orolia ART-CARD

   - WiFi:
      - MediaTek Wi-Fi 7 (802.11be) devices
      - RealTek rtw8821cu, rtw8822bu, rtw8822cu and rtw8723du USB
        devices

   - Bluetooth:
      - Broadcom BCM4377/4378/4387 Bluetooth chipsets
      - Realtek RTL8852BE and RTL8723DS
      - Cypress.CYW4373A0 WiFi + Bluetooth combo device

  Drivers:

   - CAN:
      - gs_usb: bus error reporting support
      - kvaser_usb: listen only and bus error reporting support

   - Ethernet NICs:
      - Intel (100G):
         - extend action skbedit to RX queue mapping
         - implement devlink-rate support
         - support direct read from memory
      - nVidia/Mellanox (mlx5):
         - SW steering improvements, increasing rules update rate
         - Support for enhanced events compression
         - extend H/W offload packet manipulation capabilities
         - implement IPSec packet offload mode
      - nVidia/Mellanox (mlx4):
         - better big TCP support
      - Netronome Ethernet NICs (nfp):
         - IPsec offload support
         - add support for multicast filter
      - Broadcom:
         - RSS and PTP support improvements
      - AMD/SolarFlare:
         - netlink extened ack improvements
         - add basic flower matches to offload, and related stats
      - Virtual NICs:
         - ibmvnic: introduce affinity hint support
      - small / embedded:
         - FreeScale fec: add initial XDP support
         - Marvel mv643xx_eth: support MII/GMII/RGMII modes for Kirkwood
         - TI am65-cpsw: add suspend/resume support
         - Mediatek MT7986: add RX wireless wthernet dispatch support
         - Realtek 8169: enable GRO software interrupt coalescing per
           default

   - Ethernet high-speed switches:
      - Microchip (sparx5):
         - add support for Sparx5 TC/flower H/W offload via VCAP
      - Mellanox mlxsw:
         - add 802.1X and MAC Authentication Bypass offload support
         - add ip6gre support

   - Embedded Ethernet switches:
      - Mediatek (mtk_eth_soc):
         - improve PCS implementation, add DSA untag support
         - enable flow offload support
      - Renesas:
         - add rswitch R-Car Gen4 gPTP support
      - Microchip (lan966x):
         - add full XDP support
         - add TC H/W offload via VCAP
         - enable PTP on bridge interfaces
      - Microchip (ksz8):
         - add MTU support for KSZ8 series

   - Qualcomm 802.11ax WiFi (ath11k):
      - support configuring channel dwell time during scan

   - MediaTek WiFi (mt76):
      - enable Wireless Ethernet Dispatch (WED) offload support
      - add ack signal support
      - enable coredump support
      - remain_on_channel support

   - Intel WiFi (iwlwifi):
      - enable Wi-Fi 7 Extremely High Throughput (EHT) PHY capabilities
      - 320 MHz channels support

   - RealTek WiFi (rtw89):
      - new dynamic header firmware format support
      - wake-over-WLAN support"

* tag 'net-next-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2002 commits)
  ipvs: fix type warning in do_div() on 32 bit
  net: lan966x: Remove a useless test in lan966x_ptp_add_trap()
  net: ipa: add IPA v4.7 support
  dt-bindings: net: qcom,ipa: Add SM6350 compatible
  bnxt: Use generic HBH removal helper in tx path
  IPv6/GRO: generic helper to remove temporary HBH/jumbo header in driver
  selftests: forwarding: Add bridge MDB test
  selftests: forwarding: Rename bridge_mdb test
  bridge: mcast: Support replacement of MDB port group entries
  bridge: mcast: Allow user space to specify MDB entry routing protocol
  bridge: mcast: Allow user space to add (*, G) with a source list and filter mode
  bridge: mcast: Add support for (*, G) with a source list and filter mode
  bridge: mcast: Avoid arming group timer when (S, G) corresponds to a source
  bridge: mcast: Add a flag for user installed source entries
  bridge: mcast: Expose __br_multicast_del_group_src()
  bridge: mcast: Expose br_multicast_new_group_src()
  bridge: mcast: Add a centralized error path
  bridge: mcast: Place netlink policy before validation functions
  bridge: mcast: Split (*, G) and (S, G) addition into different functions
  bridge: mcast: Do not derive entry type from its filter mode
  ...
 2022-12-13 15:47:48 -08:00
Linus Torvalds
268325bda5 Random number generator updates for Linux 6.2-rc1. 
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Merge tag 'random-6.2-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random

Pull random number generator updates from Jason Donenfeld:

 - Replace prandom_u32_max() and various open-coded variants of it,
   there is now a new family of functions that uses fast rejection
   sampling to choose properly uniformly random numbers within an
   interval:

       get_random_u32_below(ceil) - [0, ceil)
       get_random_u32_above(floor) - (floor, U32_MAX]
       get_random_u32_inclusive(floor, ceil) - [floor, ceil]

   Coccinelle was used to convert all current users of
   prandom_u32_max(), as well as many open-coded patterns, resulting in
   improvements throughout the tree.

   I'll have a "late" 6.1-rc1 pull for you that removes the now unused
   prandom_u32_max() function, just in case any other trees add a new
   use case of it that needs to converted. According to linux-next,
   there may be two trivial cases of prandom_u32_max() reintroductions
   that are fixable with a 's/.../.../'. So I'll have for you a final
   conversion patch doing that alongside the removal patch during the
   second week.

   This is a treewide change that touches many files throughout.

 - More consistent use of get_random_canary().

 - Updates to comments, documentation, tests, headers, and
   simplification in configuration.

 - The arch_get_random*_early() abstraction was only used by arm64 and
   wasn't entirely useful, so this has been replaced by code that works
   in all relevant contexts.

 - The kernel will use and manage random seeds in non-volatile EFI
   variables, refreshing a variable with a fresh seed when the RNG is
   initialized. The RNG GUID namespace is then hidden from efivarfs to
   prevent accidental leakage.

   These changes are split into random.c infrastructure code used in the
   EFI subsystem, in this pull request, and related support inside of
   EFISTUB, in Ard's EFI tree. These are co-dependent for full
   functionality, but the order of merging doesn't matter.

 - Part of the infrastructure added for the EFI support is also used for
   an improvement to the way vsprintf initializes its siphash key,
   replacing an sleep loop wart.

 - The hardware RNG framework now always calls its correct random.c
   input function, add_hwgenerator_randomness(), rather than sometimes
   going through helpers better suited for other cases.

 - The add_latent_entropy() function has long been called from the fork
   handler, but is a no-op when the latent entropy gcc plugin isn't
   used, which is fine for the purposes of latent entropy.

   But it was missing out on the cycle counter that was also being mixed
   in beside the latent entropy variable. So now, if the latent entropy
   gcc plugin isn't enabled, add_latent_entropy() will expand to a call
   to add_device_randomness(NULL, 0), which adds a cycle counter,
   without the absent latent entropy variable.

 - The RNG is now reseeded from a delayed worker, rather than on demand
   when used. Always running from a worker allows it to make use of the
   CPU RNG on platforms like S390x, whose instructions are too slow to
   do so from interrupts. It also has the effect of adding in new inputs
   more frequently with more regularity, amounting to a long term
   transcript of random values. Plus, it helps a bit with the upcoming
   vDSO implementation (which isn't yet ready for 6.2).

 - The jitter entropy algorithm now tries to execute on many different
   CPUs, round-robining, in hopes of hitting even more memory latencies
   and other unpredictable effects. It also will mix in a cycle counter
   when the entropy timer fires, in addition to being mixed in from the
   main loop, to account more explicitly for fluctuations in that timer
   firing. And the state it touches is now kept within the same cache
   line, so that it's assured that the different execution contexts will
   cause latencies.

* tag 'random-6.2-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random: (23 commits)
  random: include <linux/once.h> in the right header
  random: align entropy_timer_state to cache line
  random: mix in cycle counter when jitter timer fires
  random: spread out jitter callback to different CPUs
  random: remove extraneous period and add a missing one in comments
  efi: random: refresh non-volatile random seed when RNG is initialized
  vsprintf: initialize siphash key using notifier
  random: add back async readiness notifier
  random: reseed in delayed work rather than on-demand
  random: always mix cycle counter in add_latent_entropy()
  hw_random: use add_hwgenerator_randomness() for early entropy
  random: modernize documentation comment on get_random_bytes()
  random: adjust comment to account for removed function
  random: remove early archrandom abstraction
  random: use random.trust_{bootloader,cpu} command line option only
  stackprotector: actually use get_random_canary()
  stackprotector: move get_random_canary() into stackprotector.h
  treewide: use get_random_u32_inclusive() when possible
  treewide: use get_random_u32_{above,below}() instead of manual loop
  treewide: use get_random_u32_below() instead of deprecated function
  ...
 2022-12-12 16:22:22 -08:00
Eduard Zingerman
4ea2bb158b bpf: use check_ids() for active_lock comparison 
An update for verifier.c:states_equal()/regsafe() to use check_ids()
for active spin lock comparisons. This fixes the issue reported by
Kumar Kartikeya Dwivedi in [1] using technique suggested by Edward Cree.

W/o this commit the verifier might be tricked to accept the following
program working with a map containing spin locks:

  0: r9 = map_lookup_elem(...)  ; Returns PTR_TO_MAP_VALUE_OR_NULL id=1.
  1: r8 = map_lookup_elem(...)  ; Returns PTR_TO_MAP_VALUE_OR_NULL id=2.
  2: if r9 == 0 goto exit       ; r9 -> PTR_TO_MAP_VALUE.
  3: if r8 == 0 goto exit       ; r8 -> PTR_TO_MAP_VALUE.
  4: r7 = ktime_get_ns()        ; Unbound SCALAR_VALUE.
  5: r6 = ktime_get_ns()        ; Unbound SCALAR_VALUE.
  6: bpf_spin_lock(r8)          ; active_lock.id == 2.
  7: if r6 > r7 goto +1         ; No new information about the state
                                ; is derived from this check, thus
                                ; produced verifier states differ only
                                ; in 'insn_idx'.
  8: r9 = r8                    ; Optionally make r9.id == r8.id.
  --- checkpoint ---            ; Assume is_state_visisted() creates a
                                ; checkpoint here.
  9: bpf_spin_unlock(r9)        ; (a,b) active_lock.id == 2.
                                ; (a) r9.id == 2, (b) r9.id == 1.
 10: exit(0)

Consider two verification paths:
(a) 0-10
(b) 0-7,9-10

The path (a) is verified first. If checkpoint is created at (8)
the (b) would assume that (8) is safe because regsafe() does not
compare register ids for registers of type PTR_TO_MAP_VALUE.

[1] https://lore.kernel.org/bpf/20221111202719.982118-1-memxor@gmail.com/

Reported-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Suggested-by: Edward Cree <ecree.xilinx@gmail.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20221209135733.28851-6-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-10 13:20:53 -08:00
Eduard Zingerman
5dd9cdbc9d bpf: states_equal() must build idmap for all function frames 
verifier.c:states_equal() must maintain register ID mapping across all
function frames. Otherwise the following example might be erroneously
marked as safe:

main:
    fp[-24] = map_lookup_elem(...)  ; frame[0].fp[-24].id == 1
    fp[-32] = map_lookup_elem(...)  ; frame[0].fp[-32].id == 2
    r1 = &fp[-24]
    r2 = &fp[-32]
    call foo()
    r0 = 0
    exit

foo:
  0: r9 = r1
  1: r8 = r2
  2: r7 = ktime_get_ns()
  3: r6 = ktime_get_ns()
  4: if (r6 > r7) goto skip_assign
  5: r9 = r8

skip_assign:                ; <--- checkpoint
  6: r9 = *r9               ; (a) frame[1].r9.id == 2
                            ; (b) frame[1].r9.id == 1

  7: if r9 == 0 goto exit:  ; mark_ptr_or_null_regs() transfers != 0 info
                            ; for all regs sharing ID:
                            ;   (a) r9 != 0 => &frame[0].fp[-32] != 0
                            ;   (b) r9 != 0 => &frame[0].fp[-24] != 0

  8: r8 = *r8               ; (a) r8 == &frame[0].fp[-32]
                            ; (b) r8 == &frame[0].fp[-32]
  9: r0 = *r8               ; (a) safe
                            ; (b) unsafe

exit:
 10: exit

While processing call to foo() verifier considers the following
execution paths:

(a) 0-10
(b) 0-4,6-10
(There is also path 0-7,10 but it is not interesting for the issue at
 hand. (a) is verified first.)

Suppose that checkpoint is created at (6) when path (a) is verified,
next path (b) is verified and (6) is reached.

If states_equal() maintains separate 'idmap' for each frame the
mapping at (6) for frame[1] would be empty and
regsafe(r9)::check_ids() would add a pair 2->1 and return true,
which is an error.

If states_equal() maintains single 'idmap' for all frames the mapping
at (6) would be { 1->1, 2->2 } and regsafe(r9)::check_ids() would
return false when trying to add a pair 2->1.

This issue was suggested in the following discussion:
https://lore.kernel.org/bpf/CAEf4BzbFB5g4oUfyxk9rHy-PJSLQ3h8q9mV=rVoXfr_JVm8+1Q@mail.gmail.com/

Suggested-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20221209135733.28851-4-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-10 13:20:53 -08:00
Eduard Zingerman
7c884339bb bpf: regsafe() must not skip check_ids() 
The verifier.c:regsafe() has the following shortcut:

	equal = memcmp(rold, rcur, offsetof(struct bpf_reg_state, parent)) == 0;
	...
	if (equal)
		return true;

Which is executed regardless old register type. This is incorrect for
register types that might have an ID checked by check_ids(), namely:
 - PTR_TO_MAP_KEY
 - PTR_TO_MAP_VALUE
 - PTR_TO_PACKET_META
 - PTR_TO_PACKET

The following pattern could be used to exploit this:

  0: r9 = map_lookup_elem(...)  ; Returns PTR_TO_MAP_VALUE_OR_NULL id=1.
  1: r8 = map_lookup_elem(...)  ; Returns PTR_TO_MAP_VALUE_OR_NULL id=2.
  2: r7 = ktime_get_ns()        ; Unbound SCALAR_VALUE.
  3: r6 = ktime_get_ns()        ; Unbound SCALAR_VALUE.
  4: if r6 > r7 goto +1         ; No new information about the state
                                ; is derived from this check, thus
                                ; produced verifier states differ only
                                ; in 'insn_idx'.
  5: r9 = r8                    ; Optionally make r9.id == r8.id.
  --- checkpoint ---            ; Assume is_state_visisted() creates a
                                ; checkpoint here.
  6: if r9 == 0 goto <exit>     ; Nullness info is propagated to all
                                ; registers with matching ID.
  7: r1 = *(u64 *) r8           ; Not always safe.

Verifier first visits path 1-7 where r8 is verified to be not null
at (6). Later the jump from 4 to 6 is examined. The checkpoint for (6)
looks as follows:
  R8_rD=map_value_or_null(id=2,off=0,ks=4,vs=8,imm=0)
  R9_rwD=map_value_or_null(id=2,off=0,ks=4,vs=8,imm=0)
  R10=fp0

The current state is:
  R0=... R6=... R7=... fp-8=...
  R8=map_value_or_null(id=2,off=0,ks=4,vs=8,imm=0)
  R9=map_value_or_null(id=1,off=0,ks=4,vs=8,imm=0)
  R10=fp0

Note that R8 states are byte-to-byte identical, so regsafe() would
exit early and skip call to check_ids(), thus ID mapping 2->2 will not
be added to 'idmap'. Next, states for R9 are compared: these are not
identical and check_ids() is executed, but 'idmap' is empty, so
check_ids() adds mapping 2->1 to 'idmap' and returns success.

This commit pushes the 'equal' down to register types that don't need
check_ids().

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20221209135733.28851-2-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-10 13:20:52 -08:00
Kumar Kartikeya Dwivedi
76d16077be bpf: Use memmove for bpf_dynptr_{read,write} 
It may happen that destination buffer memory overlaps with memory dynptr
points to. Hence, we must use memmove to correctly copy from dynptr to
destination buffer, or source buffer to dynptr.

This actually isn't a problem right now, as memcpy implementation falls
back to memmove on detecting overlap and warns about it, but we
shouldn't be relying on that.

Acked-by: Joanne Koong <joannelkoong@gmail.com>
Acked-by: David Vernet <void@manifault.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20221207204141.308952-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-08 18:39:28 -08:00
Kumar Kartikeya Dwivedi
f6ee298fa1 bpf: Move PTR_TO_STACK alignment check to process_dynptr_func 
After previous commit, we are minimizing helper specific assumptions
from check_func_arg_reg_off, making it generic, and offloading checks
for a specific argument type to their respective functions called after
check_func_arg_reg_off has been called.

This allows relying on a consistent set of guarantees after that call
and then relying on them in code that deals with registers for each
argument type later. This is in line with how process_spin_lock,
process_timer_func, process_kptr_func check reg->var_off to be constant.
The same reasoning is used here to move the alignment check into
process_dynptr_func. Note that it also needs to check for constant
var_off, and accumulate the constant var_off when computing the spi in
get_spi, but that fix will come in later changes.

Acked-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20221207204141.308952-6-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-08 18:39:28 -08:00
Kumar Kartikeya Dwivedi
184c9bdb8f bpf: Rework check_func_arg_reg_off 
While check_func_arg_reg_off is the place which performs generic checks
needed by various candidates of reg->type, there is some handling for
special cases, like ARG_PTR_TO_DYNPTR, OBJ_RELEASE, and
ARG_PTR_TO_RINGBUF_MEM.

This commit aims to streamline these special cases and instead leave
other things up to argument type specific code to handle. The function
will be restrictive by default, and cover all possible cases when
OBJ_RELEASE is set, without having to update the function again (and
missing to do that being a bug).

This is done primarily for two reasons: associating back reg->type to
its argument leaves room for the list getting out of sync when a new
reg->type is supported by an arg_type.

The other case is ARG_PTR_TO_RINGBUF_MEM. The problem there is something
we already handle, whenever a release argument is expected, it should
be passed as the pointer that was received from the acquire function.
Hence zero fixed and variable offset.

There is nothing special about ARG_PTR_TO_RINGBUF_MEM, where technically
its target register type PTR_TO_MEM | MEM_RINGBUF can already be passed
with non-zero offset to other helper functions, which makes sense.

Hence, lift the arg_type_is_release check for reg->off and cover all
possible register types, instead of duplicating the same kind of check
twice for current OBJ_RELEASE arg_types (alloc_mem and ptr_to_btf_id).

For the release argument, arg_type_is_dynptr is the special case, where
we go to actual object being freed through the dynptr, so the offset of
the pointer still needs to allow fixed and variable offset and
process_dynptr_func will verify them later for the release argument case
as well.

This is not specific to ARG_PTR_TO_DYNPTR though, we will need to make
this exception for any future object on the stack that needs to be
released. In this sense, PTR_TO_STACK as a candidate for object on stack
argument is a special case for release offset checks, and they need to
be done by the helper releasing the object on stack.

Since the check has been lifted above all register type checks, remove
the duplicated check that is being done for PTR_TO_BTF_ID.

Acked-by: Joanne Koong <joannelkoong@gmail.com>
Acked-by: David Vernet <void@manifault.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20221207204141.308952-5-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-08 18:39:06 -08:00
Kumar Kartikeya Dwivedi
2706053173 bpf: Rework process_dynptr_func 
Recently, user ringbuf support introduced a PTR_TO_DYNPTR register type
for use in callback state, because in case of user ringbuf helpers,
there is no dynptr on the stack that is passed into the callback. To
reflect such a state, a special register type was created.

However, some checks have been bypassed incorrectly during the addition
of this feature. First, for arg_type with MEM_UNINIT flag which
initialize a dynptr, they must be rejected for such register type.
Secondly, in the future, there are plans to add dynptr helpers that
operate on the dynptr itself and may change its offset and other
properties.

In all of these cases, PTR_TO_DYNPTR shouldn't be allowed to be passed
to such helpers, however the current code simply returns 0.

The rejection for helpers that release the dynptr is already handled.

For fixing this, we take a step back and rework existing code in a way
that will allow fitting in all classes of helpers and have a coherent
model for dealing with the variety of use cases in which dynptr is used.

First, for ARG_PTR_TO_DYNPTR, it can either be set alone or together
with a DYNPTR_TYPE_* constant that denotes the only type it accepts.

Next, helpers which initialize a dynptr use MEM_UNINIT to indicate this
fact. To make the distinction clear, use MEM_RDONLY flag to indicate
that the helper only operates on the memory pointed to by the dynptr,
not the dynptr itself. In C parlance, it would be equivalent to taking
the dynptr as a point to const argument.

When either of these flags are not present, the helper is allowed to
mutate both the dynptr itself and also the memory it points to.
Currently, the read only status of the memory is not tracked in the
dynptr, but it would be trivial to add this support inside dynptr state
of the register.

With these changes and renaming PTR_TO_DYNPTR to CONST_PTR_TO_DYNPTR to
better reflect its usage, it can no longer be passed to helpers that
initialize a dynptr, i.e. bpf_dynptr_from_mem, bpf_ringbuf_reserve_dynptr.

A note to reviewers is that in code that does mark_stack_slots_dynptr,
and unmark_stack_slots_dynptr, we implicitly rely on the fact that
PTR_TO_STACK reg is the only case that can reach that code path, as one
cannot pass CONST_PTR_TO_DYNPTR to helpers that don't set MEM_RDONLY. In
both cases such helpers won't be setting that flag.

The next patch will add a couple of selftest cases to make sure this
doesn't break.

Fixes: 2057156738 ("bpf: Add bpf_user_ringbuf_drain() helper")
Acked-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20221207204141.308952-4-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-08 18:25:31 -08:00
Kumar Kartikeya Dwivedi
ac50fe51ce bpf: Propagate errors from process_* checks in check_func_arg 
Currently, we simply ignore the errors in process_spin_lock,
process_timer_func, process_kptr_func, process_dynptr_func. Instead,
bubble up the error by storing and checking err variable.

Acked-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20221207204141.308952-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-08 18:25:31 -08:00
Kumar Kartikeya Dwivedi
6b75bd3d03 bpf: Refactor ARG_PTR_TO_DYNPTR checks into process_dynptr_func 
ARG_PTR_TO_DYNPTR is akin to ARG_PTR_TO_TIMER, ARG_PTR_TO_KPTR, where
the underlying register type is subjected to more special checks to
determine the type of object represented by the pointer and its state
consistency.

Move dynptr checks to their own 'process_dynptr_func' function so that
is consistent and in-line with existing code. This also makes it easier
to reuse this code for kfunc handling.

Then, reuse this consolidated function in kfunc dynptr handling too.
Note that for kfuncs, the arg_type constraint of DYNPTR_TYPE_LOCAL has
been lifted.

Acked-by: David Vernet <void@manifault.com>
Acked-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20221207204141.308952-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-08 18:25:31 -08:00
Hou Tao
822ed78fab bpf: Skip rcu_barrier() if rcu_trace_implies_rcu_gp() is true 
If there are pending rcu callback, free_mem_alloc() will use
rcu_barrier_tasks_trace() and rcu_barrier() to wait for the pending
__free_rcu_tasks_trace() and __free_rcu() callback.

If rcu_trace_implies_rcu_gp() is true, there will be no pending
__free_rcu(), so it will be OK to skip rcu_barrier() as well.

Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20221209010947.3130477-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-08 17:50:17 -08:00
Hou Tao
0893d6007d bpf: Reuse freed element in free_by_rcu during allocation 
When there are batched freeing operations on a specific CPU, part of
the freed elements ((high_watermark - lower_watermark) / 2 + 1) will be
indirectly moved into waiting_for_gp list through free_by_rcu list.
After call_rcu_in_progress becomes false again, the remaining elements
in free_by_rcu list will be moved to waiting_for_gp list by the next
invocation of free_bulk(). However if the expiration of RCU tasks trace
grace period is relatively slow, none element in free_by_rcu list will
be moved.

So instead of invoking __alloc_percpu_gfp() or kmalloc_node() to
allocate a new object, in alloc_bulk() just check whether or not there is
freed element in free_by_rcu list and reuse it if available.

Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20221209010947.3130477-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-08 17:50:17 -08:00
Yang Jihong
c2cc0ce72a bpf: Fix comment error in fixup_kfunc_call function 
insn->imm for kfunc is the relative address of __bpf_call_base,
instead of __bpf_base_call, Fix the comment error.

Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
Link: https://lore.kernel.org/r/20221208013724.257848-1-yangjihong1@huawei.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-08 10:05:05 -08:00
Björn Töpel
d35af0a7fe bpf: Do not zero-extend kfunc return values 
In BPF all global functions, and BPF helpers return a 64-bit
value. For kfunc calls, this is not the case, and they can return
e.g. 32-bit values.

The return register R0 for kfuncs calls can therefore be marked as
subreg_def != DEF_NOT_SUBREG. In general, if a register is marked with
subreg_def != DEF_NOT_SUBREG, some archs (where bpf_jit_needs_zext()
returns true) require the verifier to insert explicit zero-extension
instructions.

For kfuncs calls, however, the caller should do sign/zero extension
for return values. In other words, the compiler is responsible to
insert proper instructions, not the verifier.

An example, provided by Yonghong Song:

$ cat t.c
extern unsigned foo(void);
unsigned bar1(void) {
     return foo();
}
unsigned bar2(void) {
     if (foo()) return 10; else return 20;
}

$ clang -target bpf -mcpu=v3 -O2 -c t.c && llvm-objdump -d t.o
t.o:    file format elf64-bpf

Disassembly of section .text:

0000000000000000 <bar1>:
	0:       85 10 00 00 ff ff ff ff call -0x1
	1:       95 00 00 00 00 00 00 00 exit

0000000000000010 <bar2>:
	2:       85 10 00 00 ff ff ff ff call -0x1
	3:       bc 01 00 00 00 00 00 00 w1 = w0
	4:       b4 00 00 00 14 00 00 00 w0 = 0x14
	5:       16 01 01 00 00 00 00 00 if w1 == 0x0 goto +0x1 <LBB1_2>
	6:       b4 00 00 00 0a 00 00 00 w0 = 0xa

0000000000000038 <LBB1_2>:
	7:       95 00 00 00 00 00 00 00 exit

If the return value of 'foo()' is used in the BPF program, the proper
zero-extension will be done.

Currently, the verifier correctly marks, say, a 32-bit return value as
subreg_def != DEF_NOT_SUBREG, but will fail performing the actual
zero-extension, due to a verifier bug in
opt_subreg_zext_lo32_rnd_hi32(). load_reg is not properly set to R0,
and the following path will be taken:

		if (WARN_ON(load_reg == -1)) {
			verbose(env, "verifier bug. zext_dst is set, but no reg is defined\n");
			return -EFAULT;
		}

A longer discussion from v1 can be found in the link below.

Correct the verifier by avoiding doing explicit zero-extension of R0
for kfunc calls. Note that R0 will still be marked as a sub-register
for return values smaller than 64-bit.

Fixes: 83a2881903 ("bpf: Account for BPF_FETCH in insn_has_def32()")
Link: https://lore.kernel.org/bpf/20221202103620.1915679-1-bjorn@kernel.org/
Suggested-by: Yonghong Song <yhs@meta.com>
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221207103540.396496-1-bjorn@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-08 09:59:27 -08:00
David Vernet
36aa10ffd6 bpf/docs: Document struct cgroup * kfuncs 
bpf_cgroup_acquire(), bpf_cgroup_release(), bpf_cgroup_kptr_get(), and
bpf_cgroup_ancestor(), are kfuncs that were recently added to
kernel/bpf/helpers.c. These are "core" kfuncs in that they're available
for use in any tracepoint or struct_ops BPF program. Though they have no
ABI stability guarantees, we should still document them. This patch adds
a struct cgroup * subsection to the Core kfuncs section which describes
each of these kfuncs.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20221207204911.873646-3-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-07 17:11:24 -08:00
David Vernet
25c5e92d19 bpf/docs: Document struct task_struct * kfuncs 
bpf_task_acquire(), bpf_task_release(), and bpf_task_from_pid() are
kfuncs that were recently added to kernel/bpf/helpers.c. These are
"core" kfuncs in that they're available for use for any tracepoint or
struct_ops BPF program. Though they have no ABI stability guarantees, we
should still document them. This patch adds a new Core kfuncs section to
the BPF kfuncs doc, and adds entries for all of these task kfuncs.

Note that bpf_task_kptr_get() is not documented, as it still returns
NULL while we're working to resolve how it can use RCU to ensure struct
task_struct * lifetime.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20221207204911.873646-2-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-07 17:09:13 -08:00
Andrii Nakryiko
dcb2288b1f bpf: Remove unused insn_cnt argument from visit_[func_call_]insn() 
Number of total instructions in BPF program (including subprogs) can and
is accessed from env->prog->len. visit_func_call_insn() doesn't do any
checks against insn_cnt anymore, relying on push_insn() to do this check
internally. So remove unnecessary insn_cnt input argument from
visit_func_call_insn() and visit_insn() functions.

Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20221207195534.2866030-1-andrii@kernel.org
 2022-12-07 22:58:41 +01:00
Alexei Starovoitov
0a6ea1ce82 for-alexei-2022120701 
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Merge "do not rely on ALLOW_ERROR_INJECTION for fmod_ret" into bpf-next

Merge commit 5b481acab4 ("bpf: do not rely on ALLOW_ERROR_INJECTION for fmod_ret")
from hid tree into bpf-next.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-07 13:49:21 -08:00
Benjamin Tissoires
5b481acab4 bpf: do not rely on ALLOW_ERROR_INJECTION for fmod_ret 
The current way of expressing that a non-bpf kernel component is willing
to accept that bpf programs can be attached to it and that they can change
the return value is to abuse ALLOW_ERROR_INJECTION.
This is debated in the link below, and the result is that it is not a
reasonable thing to do.

Reuse the kfunc declaration structure to also tag the kernel functions
we want to be fmodret. This way we can control from any subsystem which
functions are being modified by bpf without touching the verifier.

Link: https://lore.kernel.org/all/20221121104403.1545f9b5@gandalf.local.home/
Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20221206145936.922196-2-benjamin.tissoires@redhat.com
 2022-12-07 15:31:08 +01:00
Andrii Nakryiko
618945fbed bpf: remove unnecessary prune and jump points 
Don't mark some instructions as jump points when there are actually no
jumps and instructions are just processed sequentially. Such case is
handled naturally by precision backtracking logic without the need to
update jump history. See get_prev_insn_idx(). It goes back linearly by
one instruction, unless current top of jmp_history is pointing to
current instruction. In such case we use `st->jmp_history[cnt - 1].prev_idx`
to find instruction from which we jumped to the current instruction
non-linearly.

Also remove both jump and prune point marking for instruction right
after unconditional jumps, as program flow can get to the instruction
right after unconditional jump instruction only if there is a jump to
that instruction from somewhere else in the program. In such case we'll
mark such instruction as prune/jump point because it's a destination of
a jump.

This change has no changes in terms of number of instructions or states
processes across Cilium and selftests programs.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20221206233345.438540-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-06 19:14:38 -08:00
Andrii Nakryiko
a095f42105 bpf: mostly decouple jump history management from is_state_visited() 
Jump history updating and state equivalence checks are conceptually
independent, so move push_jmp_history() out of is_state_visited(). Also
make a decision whether to perform state equivalence checks or not one
layer higher in do_check(), keeping is_state_visited() unconditionally
performing state checks.

push_jmp_history() should be performed after state checks. There is just
one small non-uniformity. When is_state_visited() finds already
validated equivalent state, it propagates precision marks to current
state's parent chain. For this to work correctly, jump history has to be
updated, so is_state_visited() is doing that internally.

But if no equivalent verified state is found, jump history has to be
updated in a newly cloned child state, so is_jmp_point()
+ push_jmp_history() is performed after is_state_visited() exited with
zero result, which means "proceed with validation".

This change has no functional changes. It's not strictly necessary, but
feels right to decouple these two processes.

Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20221206233345.438540-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-06 19:14:38 -08:00
Andrii Nakryiko
bffdeaa8a5 bpf: decouple prune and jump points 
BPF verifier marks some instructions as prune points. Currently these
prune points serve two purposes.

It's a point where verifier tries to find previously verified state and
check current state's equivalence to short circuit verification for
current code path.

But also currently it's a point where jump history, used for precision
backtracking, is updated. This is done so that non-linear flow of
execution could be properly backtracked.

Such coupling is coincidental and unnecessary. Some prune points are not
part of some non-linear jump path, so don't need update of jump history.
On the other hand, not all instructions which have to be recorded in
jump history necessarily are good prune points.

This patch splits prune and jump points into independent flags.
Currently all prune points are marked as jump points to minimize amount
of changes in this patch, but next patch will perform some optimization
of prune vs jmp point placement.

No functional changes are intended.

Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20221206233345.438540-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-06 19:14:38 -08:00
Dave Marchevsky
d8939cb0a0 bpf: Loosen alloc obj test in verifier's reg_btf_record 
btf->struct_meta_tab is populated by btf_parse_struct_metas in btf.c.
There, a BTF record is created for any type containing a spin_lock or
any next-gen datastructure node/head.

Currently, for non-MAP_VALUE types, reg_btf_record will only search for
a record using struct_meta_tab if the reg->type exactly matches
(PTR_TO_BTF_ID | MEM_ALLOC). This exact match is too strict: an
"allocated obj" type - returned from bpf_obj_new - might pick up other
flags while working its way through the program.

Loosen the check to be exact for base_type and just use MEM_ALLOC mask
for type_flag.

This patch is marked Fixes as the original intent of reg_btf_record was
unlikely to have been to fail finding btf_record for valid alloc obj
types with additional flags, some of which (e.g. PTR_UNTRUSTED)
are valid register type states for alloc obj independent of this series.
However, I didn't find a specific broken repro case outside of this
series' added functionality, so it's possible that nothing was
triggering this logic error before.

Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
cc: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Fixes: 4e814da0d5 ("bpf: Allow locking bpf_spin_lock in allocated objects")
Link: https://lore.kernel.org/r/20221206231000.3180914-2-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-06 18:40:25 -08:00
David Vernet
156ed20d22 bpf: Don't use rcu_users to refcount in task kfuncs 
A series of prior patches added some kfuncs that allow struct
task_struct * objects to be used as kptrs. These kfuncs leveraged the
'refcount_t rcu_users' field of the task for performing refcounting.
This field was used instead of 'refcount_t usage', as we wanted to
leverage the safety provided by RCU for ensuring a task's lifetime.

A struct task_struct is refcounted by two different refcount_t fields:

1. p->usage:     The "true" refcount field which task lifetime. The
		 task is freed as soon as this refcount drops to 0.

2. p->rcu_users: An "RCU users" refcount field which is statically
		 initialized to 2, and is co-located in a union with
		 a struct rcu_head field (p->rcu). p->rcu_users
		 essentially encapsulates a single p->usage
		 refcount, and when p->rcu_users goes to 0, an RCU
		 callback is scheduled on the struct rcu_head which
		 decrements the p->usage refcount.

Our logic was that by using p->rcu_users, we would be able to use RCU to
safely issue refcount_inc_not_zero() a task's rcu_users field to
determine if a task could still be acquired, or was exiting.
Unfortunately, this does not work due to p->rcu_users and p->rcu sharing
a union. When p->rcu_users goes to 0, an RCU callback is scheduled to
drop a single p->usage refcount, and because the fields share a union,
the refcount immediately becomes nonzero again after the callback is
scheduled.

If we were to split the fields out of the union, this wouldn't be a
problem. Doing so should also be rather non-controversial, as there are
a number of places in struct task_struct that have padding which we
could use to avoid growing the structure by splitting up the fields.

For now, so as to fix the kfuncs to be correct, this patch instead
updates bpf_task_acquire() and bpf_task_release() to use the p->usage
field for refcounting via the get_task_struct() and put_task_struct()
functions. Because we can no longer rely on RCU, the change also guts
the bpf_task_acquire_not_zero() and bpf_task_kptr_get() functions
pending a resolution on the above problem.

In addition, the task fixes the kfunc and rcu_read_lock selftests to
expect this new behavior.

Fixes: 90660309b0 ("bpf: Add kfuncs for storing struct task_struct * as a kptr")
Fixes: fca1aa7551 ("bpf: Handle MEM_RCU type properly")
Reported-by: Matus Jokay <matus.jokay@stuba.sk>
Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20221206210538.597606-1-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-06 16:40:16 -08:00
Yonghong Song
2c40d97da1 bpf: Enable sleeptable support for cgrp local storage 
Similar to sk/inode/task local storage, enable sleepable support for
cgrp local storage.

Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221201050444.2785007-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-04 16:51:18 -08:00
Yonghong Song
c0c852dd18 bpf: Do not mark certain LSM hook arguments as trusted 
Martin mentioned that the verifier cannot assume arguments from
LSM hook sk_alloc_security being trusted since after the hook
is called, the sk ref_count is set to 1. This will overwrite
the ref_count changed by the bpf program and may cause ref_count
underflow later on.

I then further checked some other hooks. For example,
for bpf_lsm_file_alloc() hook in fs/file_table.c,

        f->f_cred = get_cred(cred);
        error = security_file_alloc(f);
        if (unlikely(error)) {
                file_free_rcu(&f->f_rcuhead);
                return ERR_PTR(error);
        }

        atomic_long_set(&f->f_count, 1);

The input parameter 'f' to security_file_alloc() cannot be trusted
as well.

Specifically, I investiaged bpf_map/bpf_prog/file/sk/task alloc/free
lsm hooks. Except bpf_map_alloc and task_alloc, arguments for all other
hooks should not be considered as trusted. This may not be a complete
list, but it covers common usage for sk and task.

Fixes: 3f00c52393 ("bpf: Allow trusted pointers to be passed to KF_TRUSTED_ARGS kfuncs")
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221203204954.2043348-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-04 12:59:58 -08:00
Yonghong Song
fca1aa7551 bpf: Handle MEM_RCU type properly 
Commit 9bb00b2895 ("bpf: Add kfunc bpf_rcu_read_lock/unlock()")
introduced MEM_RCU and bpf_rcu_read_lock/unlock() support. In that
commit, a rcu pointer is tagged with both MEM_RCU and PTR_TRUSTED
so that it can be passed into kfuncs or helpers as an argument.

Martin raised a good question in [1] such that the rcu pointer,
although being able to accessing the object, might have reference
count of 0. This might cause a problem if the rcu pointer is passed
to a kfunc which expects trusted arguments where ref count should
be greater than 0.

This patch makes the following changes related to MEM_RCU pointer:
  - MEM_RCU pointer might be NULL (PTR_MAYBE_NULL).
  - Introduce KF_RCU so MEM_RCU ptr can be acquired with
    a KF_RCU tagged kfunc which assumes ref count of rcu ptr
    could be zero.
  - For mem access 'b = ptr->a', say 'ptr' is a MEM_RCU ptr, and
    'a' is tagged with __rcu as well. Let us mark 'b' as
    MEM_RCU | PTR_MAYBE_NULL.

 [1] https://lore.kernel.org/bpf/ac70f574-4023-664e-b711-e0d3b18117fd@linux.dev/

Fixes: 9bb00b2895 ("bpf: Add kfunc bpf_rcu_read_lock/unlock()")
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221203184602.477272-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-04 12:52:40 -08:00
Dave Marchevsky
1f82dffc10 bpf: Fix release_on_unlock release logic for multiple refs 
Consider a verifier state with three acquired references, all with
release_on_unlock = true:

            idx  0 1 2
  state->refs = [2 4 6]

(with 2, 4, and 6 being the ref ids).

When bpf_spin_unlock is called, process_spin_lock will loop through all
acquired_refs and, for each ref, if it's release_on_unlock, calls
release_reference on it. That function in turn calls
release_reference_state, which removes the reference from state->refs by
swapping the reference state with the last reference state in
refs array and decrements acquired_refs count.

process_spin_lock's loop logic, which is essentially:

  for (i = 0; i < state->acquired_refs; i++) {
    if (!state->refs[i].release_on_unlock)
      continue;
    release_reference(state->refs[i].id);
  }

will fail to release release_on_unlock references which are swapped from
the end. Running this logic on our example demonstrates:

  state->refs = [2 4 6] (start of idx=0 iter)
    release state->refs[0] by swapping w/ state->refs[2]

  state->refs = [6 4]   (start of idx=1)
    release state->refs[1], no need to swap as it's the last idx

  state->refs = [6]     (start of idx=2, loop terminates)

ref_id 6 should have been removed but was skipped.

Fix this by looping from back-to-front, which results in refs that are
candidates for removal being swapped with refs which have already been
examined and kept.

If we modify our initial example such that ref 6 is replaced with ref 7,
which is _not_ release_on_unlock, and loop from the back, we'd see:

  state->refs = [2 4 7] (start of idx=2)

  state->refs = [2 4 7] (start of idx=1)

  state->refs = [2 7]   (start of idx=0, refs 7 and 4 swapped)

  state->refs = [7]     (after idx=0, 7 and 2 swapped, loop terminates)

Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
cc: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Fixes: 534e86bc6c ("bpf: Add 'release on unlock' logic for bpf_list_push_{front,back}")
Link: https://lore.kernel.org/r/20221201183406.1203621-1-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
 2022-12-01 19:38:17 -08:00
Yonghong Song
3144bfa507 bpf: Fix a compilation failure with clang lto build 
When building the kernel with clang lto (CONFIG_LTO_CLANG_FULL=y), the
following compilation error will appear:

  $ make LLVM=1 LLVM_IAS=1 -j
  ...
  ld.lld: error: ld-temp.o <inline asm>:26889:1: symbol 'cgroup_storage_map_btf_ids' is already defined
  cgroup_storage_map_btf_ids:;
  ^
  make[1]: *** [/.../bpf-next/scripts/Makefile.vmlinux_o:61: vmlinux.o] Error 1

In local_storage.c, we have
  BTF_ID_LIST_SINGLE(cgroup_storage_map_btf_ids, struct, bpf_local_storage_map)
Commit c4bcfb38a9 ("bpf: Implement cgroup storage available to
non-cgroup-attached bpf progs") added the above identical BTF_ID_LIST_SINGLE
definition in bpf_cgrp_storage.c. With duplicated definitions, llvm linker
complains with lto build.

Also, extracting btf_id of 'struct bpf_local_storage_map' is defined four times
for sk, inode, task and cgrp local storages. Let us define a single global one
with a different name than cgroup_storage_map_btf_ids, which also fixed
the lto compilation error.

Fixes: c4bcfb38a9 ("bpf: Implement cgroup storage available to non-cgroup-attached bpf progs")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221130052147.1591625-1-yhs@fb.com
 2022-11-30 17:13:25 -08:00
Alexei Starovoitov
c67cae551f bpf: Tighten ptr_to_btf_id checks. 
The networking programs typically don't require CAP_PERFMON, but through kfuncs
like bpf_cast_to_kern_ctx() they can access memory through PTR_TO_BTF_ID. In
such case enforce CAP_PERFMON.
Also make sure that only GPL programs can access kernel data structures.
All kfuncs require GPL already.

Also remove allow_ptr_to_map_access. It's the same as allow_ptr_leaks and
different name for the same check only causes confusion.

Fixes: fd264ca020 ("bpf: Add a kfunc to type cast from bpf uapi ctx to kernel ctx")
Fixes: 50c6b8a9ae ("selftests/bpf: Add a test for btf_type_tag "percpu"")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20221125220617.26846-1-alexei.starovoitov@gmail.com
 2022-11-30 15:33:48 -08:00
Jakub Kicinski
f2bb566f5c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 
tools/lib/bpf/ringbuf.c
  927cbb478a ("libbpf: Handle size overflow for ringbuf mmap")
  b486d19a0a ("libbpf: checkpatch: Fixed code alignments in ringbuf.c")
https://lore.kernel.org/all/20221121122707.44d1446a@canb.auug.org.au/

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
 2022-11-29 13:04:52 -08:00
Jakub Kicinski
d6dc62fca6 bpf-next-for-netdev 
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Daniel Borkmann says:

====================
bpf-next 2022-11-25

We've added 101 non-merge commits during the last 11 day(s) which contain
a total of 109 files changed, 8827 insertions(+), 1129 deletions(-).

The main changes are:

1) Support for user defined BPF objects: the use case is to allocate own
   objects, build own object hierarchies and use the building blocks to
   build own data structures flexibly, for example, linked lists in BPF,
   from Kumar Kartikeya Dwivedi.

2) Add bpf_rcu_read_{,un}lock() support for sleepable programs,
   from Yonghong Song.

3) Add support storing struct task_struct objects as kptrs in maps,
   from David Vernet.

4) Batch of BPF map documentation improvements, from Maryam Tahhan
   and Donald Hunter.

5) Improve BPF verifier to propagate nullness information for branches
   of register to register comparisons, from Eduard Zingerman.

6) Fix cgroup BPF iter infra to hold reference on the start cgroup,
   from Hou Tao.

7) Fix BPF verifier to not mark fentry/fexit program arguments as trusted
   given it is not the case for them, from Alexei Starovoitov.

8) Improve BPF verifier's realloc handling to better play along with dynamic
   runtime analysis tools like KASAN and friends, from Kees Cook.

9) Remove legacy libbpf mode support from bpftool,
   from Sahid Orentino Ferdjaoui.

10) Rework zero-len skb redirection checks to avoid potentially breaking
    existing BPF test infra users, from Stanislav Fomichev.

11) Two small refactorings which are independent and have been split out
    of the XDP queueing RFC series, from Toke Høiland-Jørgensen.

12) Fix a memory leak in LSM cgroup BPF selftest, from Wang Yufen.

13) Documentation on how to run BPF CI without patch submission,
    from Daniel Müller.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
====================

Link: https://lore.kernel.org/r/20221125012450.441-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
 2022-11-28 19:42:17 -08:00