Re: [PATCH bpf] security: Fix hook iteration for secid_to_secctx
From: Casey Schaufler <casey@schaufler-ca.com>
Date: 2020-05-20 15:15:55
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bpf, lkml
On 5/20/2020 5:56 AM, KP Singh wrote:
From: KP Singh <redacted>
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 <redacted>This looks fine.
quoted hunk ↗ jump to hunk
--- 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);