From: David Windsor <dwindsor@gmail.com> mainline inclusion from mainline-v7.2-rc1 commit 5b038319be442c620f774e6fc9e9283deeca1c75 category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/9693 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- The cgroup shim runs under rcu_read_lock_dont_migrate(), so we should not attach any sleepable BPF programs there. Add support to the verifier to explicitly reject attempts to load sleepable BPF programs destined for LSM cgroup attachment. Without this, we get the following splat from a BPF_LSM_CGROUP program marked BPF_F_SLEEPABLE attached to file_open when it calls bpf_get_dentry_xattr(): BUG: sleeping function called from invalid context at kernel/locking/rwsem.c:1567 in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 34317, name: load preempt_count: 0, expected: 0 RCU nest depth: 2, expected: 0 Call Trace: down_read+0x76/0x480 ext4_xattr_get+0x11f/0x700 __vfs_getxattr+0xf0/0x150 bpf_get_dentry_xattr+0xbb/0xf0 bpf_prog_e76a298dac9218c6_test_open+0x6a/0x85 __cgroup_bpf_run_lsm_current+0x326/0x840 bpf_trampoline_6442534646+0x62/0x14d security_file_open+0x34/0x60 do_dentry_open+0x340/0x1260 vfs_open+0x7a/0x440 path_openat+0x1bac/0x30a0 libbpf provides a .s named section variant for every sleepable program type except lsm_cgroup, reflecting that per-cgroup LSM programs are intended to only run in a non-sleepable context. The above splat was obtained by bypassing libbpf by using bpf(2) directly. Fixes: 69fd337a975c ("bpf: per-cgroup lsm flavor") Signed-off-by: David Windsor <dwindsor@gmail.com> Acked-by: Yonghong Song <yonghong.song@linux.dev> Acked-by: Song Liu <song@kernel.org> Link: https://lore.kernel.org/bpf/20260605145707.608579-1-dwindsor@gmail.com Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Conflicts: kernel/bpf/verifier.c [ctx conflicts] Signed-off-by: Pu Lehui <pulehui@huawei.com> --- kernel/bpf/verifier.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 7e2451d1a74a..3cbc46a591f9 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -20745,8 +20745,10 @@ static bool can_be_sleepable(struct bpf_prog *prog) return false; } } - return prog->type == BPF_PROG_TYPE_LSM || - prog->type == BPF_PROG_TYPE_KPROBE /* only for uprobes */ || + if (prog->type == BPF_PROG_TYPE_LSM) + return prog->expected_attach_type != BPF_LSM_CGROUP; + + return prog->type == BPF_PROG_TYPE_KPROBE /* only for uprobes */ || prog->type == BPF_PROG_TYPE_STRUCT_OPS; } -- 2.34.1