From 4c71303c837449158815c521fcee4ec3b8721dbd Mon Sep 17 00:00:00 2001 From: Xu Kuohai Date: Wed, 10 Jun 2026 20:17:23 +0000 Subject: bpf: Fix setting retval to -EPERM for cgroup hooks not returning errno When a cgroup BPF program exits with 0, bpf_prog_run_array_cg() sets the hook return value to -EPERM if it is not a valid errno. This is correct for errno-based hooks, which return 0 on success and negative errno on failure, but wrong for boolean and void LSM hooks. Boolean LSM hooks should only return true or false, and void LSM hooks have no return value at all. Fix it by skipping setting -EPERM for hooks not returning errno. Fixes: 69fd337a975c ("bpf: per-cgroup lsm flavor") Signed-off-by: Xu Kuohai Link: https://lore.kernel.org/r/20260610201724.733943-2-xukuohai@huaweicloud.com Signed-off-by: Alexei Starovoitov --- include/linux/bpf_lsm.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux') diff --git a/include/linux/bpf_lsm.h b/include/linux/bpf_lsm.h index 643809cc78c3..143775a27a2a 100644 --- a/include/linux/bpf_lsm.h +++ b/include/linux/bpf_lsm.h @@ -52,6 +52,7 @@ int bpf_set_dentry_xattr_locked(struct dentry *dentry, const char *name__str, const struct bpf_dynptr *value_p, int flags); int bpf_remove_dentry_xattr_locked(struct dentry *dentry, const char *name__str); bool bpf_lsm_has_d_inode_locked(const struct bpf_prog *prog); +bool bpf_lsm_hook_returns_errno(u32 btf_id); #else /* !CONFIG_BPF_LSM */ @@ -104,6 +105,11 @@ static inline bool bpf_lsm_has_d_inode_locked(const struct bpf_prog *prog) { return false; } + +static inline bool bpf_lsm_hook_returns_errno(u32 btf_id) +{ + return true; +} #endif /* CONFIG_BPF_LSM */ #endif /* _LINUX_BPF_LSM_H */ -- cgit v1.2.3