[PATCH 5.10.y] apparmor: remove fs entries created by a failed policy load

[Sasha Levin <sashal@kernel.org>]

From: Georgia Garcia <georgia.garcia@canonical.com>

[ Upstream commit 6ec46f8f1977d218bf2494ce276152b2d01424af ]

aa_replace_profiles() creates the raw_data/<rev> directory for the
loaddata and the profile directories for new profiles before the last
checks that can fail. When one of those checks fails, the fail path
releases the ns lock without removing what this load created.

The raw_data directory is named after the current ns revision, and the
revision is only bumped by a successful load. The stale directory is
only removed once the loaddata's last profile reference is dropped, from
a workqueue. Until then, every load fails to create raw_data/<rev> with
-EEXIST. If the new profiles are never freed, which is the case when
their dents are left behind pinning the proxy, that never happens and no
policy can be loaded until reboot.

While still holding the ns lock in the fail path, remove the profile
directories of the new profiles and, if this load created it, the
raw_data directory.

Fixes: 5d5182cae401 ("apparmor: move to per loaddata files, instead of replicating in profiles")
Cc: stable@vger.kernel.org
Signed-off-by: Georgia Garcia <georgia.garcia@canonical.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
[ sashal: Adjusted context for different local variable declarations in aa_replace_profiles(). ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 security/apparmor/policy.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/security/apparmor/policy.c b/security/apparmor/policy.c
index f3592af433553..dd8439e9cf55b 100644
--- a/security/apparmor/policy.c
+++ b/security/apparmor/policy.c
@@ -923,6 +923,7 @@ ssize_t aa_replace_profiles(struct aa_ns *policy_ns, struct aa_label *label,
 	const char *op;
 	ssize_t count, error;
 	ssize_t udata_sz;
+	bool rawdata_created = false;
 	LIST_HEAD(lh);
 
 	op = mask & AA_MAY_REPLACE_POLICY ? OP_PROF_REPL : OP_PROF_LOAD;
@@ -1041,6 +1042,7 @@ ssize_t aa_replace_profiles(struct aa_ns *policy_ns, struct aa_label *label,
 			ent = NULL;
 			goto fail_lock;
 		}
+		rawdata_created = true;
 	}
 	list_for_each_entry(ent, &lh, list) {
 		if (!ent->old) {
@@ -1119,6 +1121,18 @@ ssize_t aa_replace_profiles(struct aa_ns *policy_ns, struct aa_label *label,
 	return udata_sz;
 
 fail_lock:
+	/*
+	 * Remove fs entries created by this load. Nothing else references
+	 * them yet, and leaving them behind would leak the new profiles
+	 * (their dents pin the proxy) and make the next load at the same,
+	 * unbumped ns revision fail with -EEXIST on its raw_data dir.
+	 */
+	list_for_each_entry(tmp, &lh, list) {
+		if (!tmp->old)
+			__aafs_profile_rmdir(tmp->new);
+	}
+	if (rawdata_created)
+		__aa_fs_remove_rawdata(udata);
 	mutex_unlock(&ns->lock);
 
 	/* audit cause of failure */
-- 
2.53.0