From: Casey Schaufler <casey@schaufler-ca.com>
To: Christian Brauner <christian@brauner.io>,
Paul Moore <paul@paul-moore.com>,
James Morris <jmorris@namei.org>,
Linux Security Module list
<linux-security-module@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
syzbot <syzbot+d1e3b1d92d25abf97943@syzkaller.appspotmail.com>,
David Howells <dhowells@redhat.com>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Subject: [PATCH] LSM: general protection fault in legacy_parse_param
Date: Mon, 11 Oct 2021 15:40:22 -0700 [thread overview]
Message-ID: <018a9bb4-accb-c19a-5b0a-fde22f4bc822@schaufler-ca.com> (raw)
In-Reply-To: 018a9bb4-accb-c19a-5b0a-fde22f4bc822.ref@schaufler-ca.com
The usual LSM hook "bail on fail" scheme doesn't work for cases where
a security module may return an error code indicating that it does not
recognize an input. In this particular case Smack sees a mount option
that it recognizes, and returns 0. A call to a BPF hook follows, which
returns -ENOPARAM, which confuses the caller because Smack has processed
its data.
Reported-by: syzbot+d1e3b1d92d25abf97943@syzkaller.appspotmail.com
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
security/security.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/security/security.c b/security/security.c
index 09533cbb7221..3cf0faaf1c5b 100644
--- a/security/security.c
+++ b/security/security.c
@@ -885,7 +885,19 @@ int security_fs_context_dup(struct fs_context *fc, struct fs_context *src_fc)
int security_fs_context_parse_param(struct fs_context *fc, struct fs_parameter *param)
{
- return call_int_hook(fs_context_parse_param, -ENOPARAM, fc, param);
+ struct security_hook_list *hp;
+ int trc;
+ int rc = -ENOPARAM;
+
+ hlist_for_each_entry(hp, &security_hook_heads.fs_context_parse_param,
+ list) {
+ trc = hp->hook.fs_context_parse_param(fc, param);
+ if (trc == 0)
+ rc = 0;
+ else if (trc != -ENOPARAM)
+ return trc;
+ }
+ return rc;
}
int security_sb_alloc(struct super_block *sb)
next parent reply other threads:[~2021-10-11 22:40 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <018a9bb4-accb-c19a-5b0a-fde22f4bc822.ref@schaufler-ca.com>
2021-10-11 22:40 ` Casey Schaufler [this message]
2021-10-12 10:32 ` [PATCH] LSM: general protection fault in legacy_parse_param Christian Brauner
2021-10-12 14:27 ` Casey Schaufler
2022-01-25 22:18 ` Paul Moore
2022-01-25 23:30 ` Casey Schaufler
2022-01-25 23:36 ` Paul Moore
2022-01-26 7:24 ` Christian Brauner
2022-01-26 22:37 ` Paul Moore
2022-01-27 16:51 ` [PATCH v2] " Casey Schaufler
2022-01-27 17:33 ` James Morris
2022-01-28 1:44 ` Paul Moore
2022-01-28 2:33 ` Casey Schaufler
2022-01-28 8:59 ` Christian Brauner
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