linux-stable.git/kernel/bpf, branch v5.16.9

bpf: Use VM_MAP instead of VM_ALLOC for ringbuf

2022-02-08T17:35:17+00:00

commit b293dcc473d22a62dc6d78de2b15e4f49515db56 upstream.

After commit 2fd3fb0be1d1 ("kasan, vmalloc: unpoison VM_ALLOC pages
after mapping"), non-VM_ALLOC mappings will be marked as accessible
in __get_vm_area_node() when KASAN is enabled. But now the flag for
ringbuf area is VM_ALLOC, so KASAN will complain out-of-bound access
after vmap() returns. Because the ringbuf area is created by mapping
allocated pages, so use VM_MAP instead.

After the change, info in /proc/vmallocinfo also changes from
  [start]-[end]   24576 ringbuf_map_alloc+0x171/0x290 vmalloc user
to
  [start]-[end]   24576 ringbuf_map_alloc+0x171/0x290 vmap user

Fixes: 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it")
Reported-by: syzbot+5ad567a418794b9b5983@syzkaller.appspotmail.com
Signed-off-by: Hou Tao 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20220202060158.6260-1-houtao1@huawei.com
Signed-off-by: Greg Kroah-Hartman

bpf: Fix possible race in inc_misses_counter

2022-02-05T11:39:58+00:00

commit 0e3135d3bfa5dfb658145238d2bc723a8e30c3a3 upstream.

It seems inc_misses_counter() suffers from same issue fixed in
the commit d979617aa84d ("bpf: Fixes possible race in update_prog_stats()
for 32bit arches"):
As it can run while interrupts are enabled, it could
be re-entered and the u64_stats syncp could be mangled.

Fixes: 9ed9e9ba2337 ("bpf: Count the number of times recursion was prevented")
Signed-off-by: He Fengqing 
Acked-by: John Fastabend 
Link: https://lore.kernel.org/r/20220122102936.1219518-1-hefengqing@huawei.com
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Greg Kroah-Hartman

bpf: Guard against accessing NULL pt_regs in bpf_get_task_stack()

2022-02-01T16:29:01+00:00

commit b992f01e66150fc5e90be4a96f5eb8e634c8249e upstream.

task_pt_regs() can return NULL on powerpc for kernel threads. This is
then used in __bpf_get_stack() to check for user mode, resulting in a
kernel oops. Guard against this by checking return value of
task_pt_regs() before trying to obtain the call chain.

Fixes: fa28dcb82a38f8 ("bpf: Introduce helper bpf_get_task_stack()")
Cc: stable@vger.kernel.org # v5.9+
Signed-off-by: Naveen N. Rao 
Acked-by: Daniel Borkmann 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/d5ef83c361cc255494afd15ff1b4fb02a36e1dcf.1641468127.git.naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Greg Kroah-Hartman

bpf: Mark PTR_TO_FUNC register initially with zero offset

2022-01-27T11:02:54+00:00

commit d400a6cf1c8a57cdf10f35220ead3284320d85ff upstream.

Similar as with other pointer types where we use ldimm64, clear the register
content to zero first, and then populate the PTR_TO_FUNC type and subprogno
number. Currently this is not done, and leads to reuse of stale register
tracking data.

Given for special ldimm64 cases we always clear the register offset, make it
common for all cases, so it won't be forgotten in future.

Fixes: 69c087ba6225 ("bpf: Add bpf_for_each_map_elem() helper")
Signed-off-by: Daniel Borkmann 
Acked-by: John Fastabend 
Acked-by: Alexei Starovoitov 
Signed-off-by: Greg Kroah-Hartman

bpf: Fix mount source show for bpffs

2022-01-27T11:02:54+00:00

commit 1e9d74660d4df625b0889e77018f9e94727ceacd upstream.

We noticed our tc ebpf tools can't start after we upgrade our in-house kernel
version from 4.19 to 5.10. That is because of the behaviour change in bpffs
caused by commit d2935de7e4fd ("vfs: Convert bpf to use the new mount API").

In our tc ebpf tools, we do strict environment check. If the environment is
not matched, we won't allow to start the ebpf progs. One of the check is whether
bpffs is properly mounted. The mount information of bpffs in kernel-4.19 and
kernel-5.10 are as follows:

- kernel 4.19
$ mount -t bpf bpffs /sys/fs/bpf
$ mount -t bpf
bpffs on /sys/fs/bpf type bpf (rw,relatime)

- kernel 5.10
$ mount -t bpf bpffs /sys/fs/bpf
$ mount -t bpf
none on /sys/fs/bpf type bpf (rw,relatime)

The device name in kernel-5.10 is displayed as none instead of bpffs, then our
environment check fails. Currently we modify the tools to adopt to the kernel
behaviour change, but I think we'd better change the kernel code to keep the
behavior consistent.

After this change, the mount information will be displayed the same with the
behavior in kernel-4.19, for example:

$ mount -t bpf bpffs /sys/fs/bpf
$ mount -t bpf
bpffs on /sys/fs/bpf type bpf (rw,relatime)

Fixes: d2935de7e4fd ("vfs: Convert bpf to use the new mount API")
Suggested-by: Daniel Borkmann 
Signed-off-by: Yafang Shao 
Signed-off-by: Daniel Borkmann 
Acked-by: Christian Brauner 
Cc: David Howells 
Cc: Al Viro 
Link: https://lore.kernel.org/bpf/20220108134623.32467-1-laoar.shao@gmail.com
Signed-off-by: Greg Kroah-Hartman

bpf: Change value of MAX_TAIL_CALL_CNT from 32 to 33

2022-01-27T11:02:14+00:00

[ Upstream commit ebf7f6f0a6cdcc17a3da52b81e4b3a98c4005028 ]

In the current code, the actual max tail call count is 33 which is greater
than MAX_TAIL_CALL_CNT (defined as 32). The actual limit is not consistent
with the meaning of MAX_TAIL_CALL_CNT and thus confusing at first glance.
We can see the historical evolution from commit 04fd61ab36ec ("bpf: allow
bpf programs to tail-call other bpf programs") and commit f9dabe016b63
("bpf: Undo off-by-one in interpreter tail call count limit"). In order
to avoid changing existing behavior, the actual limit is 33 now, this is
reasonable.

After commit 874be05f525e ("bpf, tests: Add tail call test suite"), we can
see there exists failed testcase.

On all archs when CONFIG_BPF_JIT_ALWAYS_ON is not set:
 # echo 0 > /proc/sys/net/core/bpf_jit_enable
 # modprobe test_bpf
 # dmesg | grep -w FAIL
 Tail call error path, max count reached jited:0 ret 34 != 33 FAIL

On some archs:
 # echo 1 > /proc/sys/net/core/bpf_jit_enable
 # modprobe test_bpf
 # dmesg | grep -w FAIL
 Tail call error path, max count reached jited:1 ret 34 != 33 FAIL

Although the above failed testcase has been fixed in commit 18935a72eb25
("bpf/tests: Fix error in tail call limit tests"), it would still be good
to change the value of MAX_TAIL_CALL_CNT from 32 to 33 to make the code
more readable.

The 32-bit x86 JIT was using a limit of 32, just fix the wrong comments and
limit to 33 tail calls as the constant MAX_TAIL_CALL_CNT updated. For the
mips64 JIT, use "ori" instead of "addiu" as suggested by Johan Almbladh.
For the riscv JIT, use RV_REG_TCC directly to save one register move as
suggested by Björn Töpel. For the other implementations, no function changes,
it does not change the current limit 33, the new value of MAX_TAIL_CALL_CNT
can reflect the actual max tail call count, the related tail call testcases
in test_bpf module and selftests can work well for the interpreter and the
JIT.

Here are the test results on x86_64:

 # uname -m
 x86_64
 # echo 0 > /proc/sys/net/core/bpf_jit_enable
 # modprobe test_bpf test_suite=test_tail_calls
 # dmesg | tail -1
 test_bpf: test_tail_calls: Summary: 8 PASSED, 0 FAILED, [0/8 JIT'ed]
 # rmmod test_bpf
 # echo 1 > /proc/sys/net/core/bpf_jit_enable
 # modprobe test_bpf test_suite=test_tail_calls
 # dmesg | tail -1
 test_bpf: test_tail_calls: Summary: 8 PASSED, 0 FAILED, [8/8 JIT'ed]
 # rmmod test_bpf
 # ./test_progs -t tailcalls
 #142 tailcalls:OK
 Summary: 1/11 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Tiezhu Yang 
Signed-off-by: Daniel Borkmann 
Tested-by: Johan Almbladh 
Tested-by: Ilya Leoshkevich 
Acked-by: Björn Töpel 
Acked-by: Johan Almbladh 
Acked-by: Ilya Leoshkevich 
Link: https://lore.kernel.org/bpf/1636075800-3264-1-git-send-email-yangtiezhu@loongson.cn
Signed-off-by: Sasha Levin

bpf: Fix verifier support for validation of async callbacks

2022-01-27T11:01:55+00:00

[ Upstream commit a5bebc4f00dee47113eed48098c68e88b5ba70e8 ]

Commit bfc6bb74e4f1 ("bpf: Implement verifier support for validation of async callbacks.")
added support for BPF_FUNC_timer_set_callback to
the __check_func_call() function.  The test in __check_func_call() is
flaweed because it can mis-interpret a regular BPF-to-BPF pseudo-call
as a BPF_FUNC_timer_set_callback callback call.

Consider the conditional in the code:

	if (insn->code == (BPF_JMP | BPF_CALL) &&
	    insn->imm == BPF_FUNC_timer_set_callback) {

The BPF_FUNC_timer_set_callback has value 170.  This means that if you
have a BPF program that contains a pseudo-call with an instruction delta
of 170, this conditional will be found to be true by the verifier, and
it will interpret the pseudo-call as a callback.  This leads to a mess
with the verification of the program because it makes the wrong
assumptions about the nature of this call.

Solution: include an explicit check to ensure that insn->src_reg == 0.
This ensures that calls cannot be mis-interpreted as an async callback
call.

Fixes: bfc6bb74e4f1 ("bpf: Implement verifier support for validation of async callbacks.")
Signed-off-by: Kris Van Hees 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20220105210150.GH1559@oracle.com
Signed-off-by: Sasha Levin

bpf: Don't promote bogus looking registers after null check.

2022-01-27T11:01:55+00:00

[ Upstream commit e60b0d12a95dcf16a63225cead4541567f5cb517 ]

If we ever get to a point again where we convert a bogus looking _or_null
typed register containing a non-zero fixed or variable offset, then lets not
reset these bounds to zero since they are not and also don't promote the register
to a  type, but instead leave it as _or_null. Converting to a unknown
register could be an avenue as well, but then if we run into this case it would
allow to leak a kernel pointer this way.

Fixes: f1174f77b50c ("bpf/verifier: rework value tracking")
Signed-off-by: Daniel Borkmann 
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Sasha Levin

bpf: Add missing map_get_next_key method to bloom filter map.

2022-01-27T11:01:53+00:00

[ Upstream commit 3ccdcee28415c4226de05438b4d89eb5514edf73 ]

Without it, kernel crashes in map_get_next_key().

Fixes: 9330986c0300 ("bpf: Add bloom filter map implementation")
Reported-by: TCS Robot 
Signed-off-by: Haimin Zhang 
Signed-off-by: Alexei Starovoitov 
Acked-by: Joanne Koong 
Link: https://lore.kernel.org/bpf/1640776802-22421-1-git-send-email-tcs.kernel@gmail.com
Signed-off-by: Sasha Levin

bpf: Disallow BPF_LOG_KERNEL log level for bpf(BPF_BTF_LOAD)

2022-01-27T11:01:40+00:00

[ Upstream commit 866de407444398bc8140ea70de1dba5f91cc34ac ]

BPF_LOG_KERNEL is only used internally, so disallow bpf_btf_load()
to set log level as BPF_LOG_KERNEL. The same checking has already
been done in bpf_check(), so factor out a helper to check the
validity of log attributes and use it in both places.

Fixes: 8580ac9404f6 ("bpf: Process in-kernel BTF")
Signed-off-by: Hou Tao 
Signed-off-by: Alexei Starovoitov 
Acked-by: Yonghong Song 
Acked-by: Martin KaFai Lau 
Link: https://lore.kernel.org/bpf/20211203053001.740945-1-houtao1@huawei.com
Signed-off-by: Sasha Levin