Kernel test robot reported bpf selftest build failure when CONFIG_SMP
is not set. The error message looks below:
>> progs/rcu_read_lock.c:256:34: error: no member named 'last_wakee' in 'struct task_struct'
last_wakee = task->real_parent->last_wakee;
~~~~~~~~~~~~~~~~~ ^
1 error generated.
When CONFIG_SMP is not set, the field 'last_wakee' is not available in struct
'task_struct'. Hence the above compilation failure. To fix the issue, let us
choose another field 'group_leader' which is available regardless of
CONFIG_SMP set or not.
Fixes: fe147956fc ("bpf/selftests: Add selftests for new task kfuncs")
Fixes: 48671232fc ("selftests/bpf: Add tests for bpf_rcu_read_lock()")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: David Vernet <void@manifault.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/bpf/20221213012224.379581-1-yhs@fb.com
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>
Add some selftest testcases that validate the expected behavior of the
bpf_task_from_pid() kfunc that was added in the prior patch.
Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20221122145300.251210-3-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
A previous change added a series of kfuncs for storing struct
task_struct objects as referenced kptrs. This patch adds a new
task_kfunc test suite for validating their expected behavior.
Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20221120051004.3605026-5-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
