Merge tag 'apparmor-pr-2024-07-25' of git://git.kernel.org/pub/scm/linux/kernel/git/jj/linux-apparmor

Pull apparmor updates from John Johansen:
"Cleanups
- optimization: try to avoid refing the label in apparmor_file_open
- remove useless static inline function is_deleted
- use kvfree_sensitive to free data->data
- fix typo in kernel doc

Bug fixes:
- unpack transition table if dfa is not present
- test: add MODULE_DESCRIPTION()
- take nosymfollow flag into account
- fix possible NULL pointer dereference
- fix null pointer deref when receiving skb during sock creation"

* tag 'apparmor-pr-2024-07-25' of git://git.kernel.org/pub/scm/linux/kernel/git/jj/linux-apparmor:
apparmor: unpack transition table if dfa is not present
apparmor: try to avoid refing the label in apparmor_file_open
apparmor: test: add MODULE_DESCRIPTION()
apparmor: take nosymfollow flag into account
apparmor: fix possible NULL pointer dereference
apparmor: fix typo in kernel doc
apparmor: remove useless static inline function is_deleted
apparmor: use kvfree_sensitive to free data->data
apparmor: Fix null pointer deref when receiving skb during sock creation

security/apparmor/apparmorfs.c

···
 		struct aa_profile *p;
 		p = aa_deref_parent(profile);
 		dent = prof_dir(p);
+		if (!dent) {
+			error = -ENOENT;
+			goto fail2;
+		}
 		/* adding to parent that previously didn't have children */
 		dent = aafs_create_dir("profiles", dent);
 		if (IS_ERR(dent))

security/apparmor/file.c

···
 	return aa_audit(type, profile, &ad, file_audit_cb);
 }
 
-/**
- * is_deleted - test if a file has been completely unlinked
- * @dentry: dentry of file to test for deletion  (NOT NULL)
- *
- * Returns: true if deleted else false
- */
-static inline bool is_deleted(struct dentry *dentry)
-{
-	if (d_unlinked(dentry) && d_backing_inode(dentry)->i_nlink == 0)
-		return true;
-	return false;
-}
-
 static int path_name(const char *op, const struct cred *subj_cred,
 		     struct aa_label *label,
 		     const struct path *path, int flags, char *buffer,

security/apparmor/include/cred.h

···
 	return aa_get_newest_label(aa_cred_raw_label(cred));
 }
 
+static inline struct aa_label *aa_get_newest_cred_label_condref(const struct cred *cred,
+								bool *needput)
+{
+	struct aa_label *l = aa_cred_raw_label(cred);
+
+	if (unlikely(label_is_stale(l))) {
+		*needput = true;
+		return aa_get_newest_label(l);
+	}
+
+	*needput = false;
+	return l;
+}
+
+static inline void aa_put_label_condref(struct aa_label *l, bool needput)
+{
+	if (unlikely(needput))
+		aa_put_label(l);
+}
+
 /**
  * aa_current_raw_label - find the current tasks confining label
  *

security/apparmor/lsm.c

···
 	struct aa_file_ctx *fctx = file_ctx(file);
 	struct aa_label *label;
 	int error = 0;
+	bool needput;
 
 	if (!path_mediated_fs(file->f_path.dentry))
 		return 0;
···
 		return 0;
 	}
 
-	label = aa_get_newest_cred_label(file->f_cred);
+	label = aa_get_newest_cred_label_condref(file->f_cred, &needput);
 	if (!unconfined(label)) {
 		struct mnt_idmap *idmap = file_mnt_idmap(file);
 		struct inode *inode = file_inode(file);
···
 		/* todo cache full allowed permissions set and state */
 		fctx->allow = aa_map_file_to_perms(file);
 	}
-	aa_put_label(label);
+	aa_put_label_condref(label, needput);
 
 	return error;
 }
···
  * @sock: socket that is being setup
  * @family: family of socket being created
  * @type: type of the socket
- * @ptotocol: protocol of the socket
+ * @protocol: protocol of the socket
  * @kern: socket is a special kernel socket
  *
  * Note:
···
 
 	if (!skb->secmark)
 		return 0;
+
+	/*
+	 * If reach here before socket_post_create hook is called, in which
+	 * case label is null, drop the packet.
+	 */
+	if (!ctx->label)
+		return -EACCES;
 
 	return apparmor_secmark_check(ctx->label, OP_RECVMSG, AA_MAY_RECEIVE,
 				      skb->secmark, sk);

security/apparmor/mount.c

···
 		audit_log_format(ab, ", mand");
 	if (flags & MS_DIRSYNC)
 		audit_log_format(ab, ", dirsync");
+	if (flags & MS_NOSYMFOLLOW)
+		audit_log_format(ab, ", nosymfollow");
 	if (flags & MS_NOATIME)
 		audit_log_format(ab, ", noatime");
 	if (flags & MS_NODIRATIME)

security/apparmor/policy.c

···
 {
 	struct aa_data *data = ptr;
 
-	kfree_sensitive(data->data);
+	kvfree_sensitive(data->data, data->size);
 	kfree_sensitive(data->key);
 	kfree_sensitive(data);
 }

security/apparmor/policy_unpack.c

···
 			*info = "missing required dfa";
 			goto fail;
 		}
-		goto out;
+	} else {
+		/*
+		 * only unpack the following if a dfa is present
+		 *
+		 * sadly start was given different names for file and policydb
+		 * but since it is optional we can try both
+		 */
+		if (!aa_unpack_u32(e, &pdb->start[0], "start"))
+			/* default start state */
+			pdb->start[0] = DFA_START;
+		if (!aa_unpack_u32(e, &pdb->start[AA_CLASS_FILE], "dfa_start")) {
+			/* default start state for xmatch and file dfa */
+			pdb->start[AA_CLASS_FILE] = DFA_START;
+		}	/* setup class index */
+		for (i = AA_CLASS_FILE + 1; i <= AA_CLASS_LAST; i++) {
+			pdb->start[i] = aa_dfa_next(pdb->dfa, pdb->start[0],
+						    i);
+		}
 	}
 
 	/*
-	 * only unpack the following if a dfa is present
-	 *
-	 * sadly start was given different names for file and policydb
-	 * but since it is optional we can try both
+	 * Unfortunately due to a bug in earlier userspaces, a
+	 * transition table may be present even when the dfa is
+	 * not. For compatibility reasons unpack and discard.
 	 */
-	if (!aa_unpack_u32(e, &pdb->start[0], "start"))
-		/* default start state */
-		pdb->start[0] = DFA_START;
-	if (!aa_unpack_u32(e, &pdb->start[AA_CLASS_FILE], "dfa_start")) {
-		/* default start state for xmatch and file dfa */
-		pdb->start[AA_CLASS_FILE] = DFA_START;
-	}	/* setup class index */
-	for (i = AA_CLASS_FILE + 1; i <= AA_CLASS_LAST; i++) {
-		pdb->start[i] = aa_dfa_next(pdb->dfa, pdb->start[0],
-					       i);
-	}
 	if (!unpack_trans_table(e, &pdb->trans) && required_trans) {
 		*info = "failed to unpack profile transition table";
 		goto fail;
 	}
 
+	if (!pdb->dfa && pdb->trans.table)
+		aa_free_str_table(&pdb->trans);
+
 	/* TODO: move compat mapping here, requires dfa merging first */
 	/* TODO: move verify here, it has to be done after compat mappings */
-out:
+
 	*policy = pdb;
 	return 0;
 
···
 
 			if (rhashtable_insert_fast(profile->data, &data->head,
 						   profile->data->p)) {
+				kvfree_sensitive(data->data, data->size);
 				kfree_sensitive(data->key);
 				kfree_sensitive(data);
 				info = "failed to insert data to table";

security/apparmor/policy_unpack_test.c

···
 
 kunit_test_suite(apparmor_policy_unpack_test_module);
 
+MODULE_DESCRIPTION("KUnit tests for AppArmor's policy unpack");
 MODULE_LICENSE("GPL");