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Subject[PATCH bpf] security: Fix hook iteration for secid_to_secctx
Date
From: KP Singh <kpsingh@google.com>

secid_to_secctx is not stackable, and since the BPF LSM registers this
hook by default, the call_int_hook logic is not suitable which
"bails-on-fail" and casues issues when other LSMs register this hook and
eventually breaks Audit.

In order to fix this, directly iterate over the security hooks instead
of using call_int_hook as suggested in:

https: //lore.kernel.org/bpf/9d0eb6c6-803a-ff3a-5603-9ad6d9edfc00@schaufler-ca.com/#t

Fixes: 98e828a0650f ("security: Refactor declaration of LSM hooks")
Fixes: 625236ba3832 ("security: Fix the default value of secid_to_secctx hook"
Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: KP Singh <kpsingh@google.com>
---
security/security.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/security/security.c b/security/security.c
index 7fed24b9d57e..51de970fbb1e 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1965,8 +1965,20 @@ EXPORT_SYMBOL(security_ismaclabel);

int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
{
- return call_int_hook(secid_to_secctx, -EOPNOTSUPP, secid, secdata,
- seclen);
+ struct security_hook_list *hp;
+ int rc;
+
+ /*
+ * Currently, only one LSM can implement secid_to_secctx (i.e this
+ * LSM hook is not "stackable").
+ */
+ hlist_for_each_entry(hp, &security_hook_heads.secid_to_secctx, list) {
+ rc = hp->hook.secid_to_secctx(secid, secdata, seclen);
+ if (rc != LSM_RET_DEFAULT(secid_to_secctx))
+ return rc;
+ }
+
+ return LSM_RET_DEFAULT(secid_to_secctx);
}
EXPORT_SYMBOL(security_secid_to_secctx);

--
2.26.2.761.g0e0b3e54be-goog
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