kernel/tools/testing/selftests/bpf/progs/task_kfunc_failure.c, branch linux-6.2.y

selftests/bpf: Fix a selftest compilation error with CONFIG_SMP=n

2022-12-14T17:35:41Z

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: fe147956fca4 ("bpf/selftests: Add selftests for new task kfuncs") Fixes: 48671232fcb8 ("selftests/bpf: Add tests for bpf_rcu_read_lock()") Reported-by: kernel test robot Signed-off-by: David Vernet Signed-off-by: Yonghong Song Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Acked-by: David Vernet Link: https://lore.kernel.org/bpf/20221213012224.379581-1-yhs@fb.com

bpf: Do not mark certain LSM hook arguments as trusted

2022-12-04T20:59:58Z

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: 3f00c5239344 ("bpf: Allow trusted pointers to be passed to KF_TRUSTED_ARGS kfuncs") Signed-off-by: Yonghong Song Link: https://lore.kernel.org/r/20221203204954.2043348-1-yhs@fb.com Signed-off-by: Alexei Starovoitov

selftests/bpf: Add selftests for bpf_task_from_pid()

2022-11-24T01:45:30Z

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 Link: https://lore.kernel.org/r/20221122145300.251210-3-void@manifault.com Signed-off-by: Alexei Starovoitov

bpf/selftests: Add selftests for new task kfuncs

2022-11-20T17:16:21Z

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 Link: https://lore.kernel.org/r/20221120051004.3605026-5-void@manifault.com Signed-off-by: Alexei Starovoitov