apparmor: provide base for multiple profiles to be replaced at once

previously profiles had to be loaded one at a time, which could result
in cases where a replacement of a set would partially succeed, and then fail
resulting in inconsistent policy.

Allow multiple profiles to replaced "atomically" so that the replacement
either succeeds or fails for the entire set of profiles.

Signed-off-by: John Johansen <john.johansen@canonical.com>

1 files changed, 86 insertions, 28 deletions

diff --git a/security/apparmor/policy_unpack.c b/security/apparmor/policy_unpack.c
index 6dac7d77cb4d..080a26b11f01 100644
--- a/security/apparmor/policy_unpack.c
+++ b/security/apparmor/policy_unpack.c
@@ -333,8 +333,10 @@ static struct aa_dfa *unpack_dfa(struct aa_ext *e)
 		/*
 		 * The dfa is aligned with in the blob to 8 bytes
 		 * from the beginning of the stream.
+		 * alignment adjust needed by dfa unpack
 		 */
-		size_t sz = blob - (char *)e->start;
+		size_t sz = blob - (char *) e->start -
+			((e->pos - e->start) & 7);
 		size_t pad = ALIGN(sz, 8) - sz;
 		int flags = TO_ACCEPT1_FLAG(YYTD_DATA32) |
 			TO_ACCEPT2_FLAG(YYTD_DATA32);
@@ -622,29 +624,41 @@ fail:
 /**
  * verify_head - unpack serialized stream header
  * @e: serialized data read head (NOT NULL)
+ * @required: whether the header is required or optional
  * @ns: Returns - namespace if one is specified else NULL (NOT NULL)
  *
  * Returns: error or 0 if header is good
  */
-static int verify_header(struct aa_ext *e, const char **ns)
+static int verify_header(struct aa_ext *e, int required, const char **ns)
 {
 	int error = -EPROTONOSUPPORT;
+	const char *name = NULL;
+	*ns = NULL;
+
 	/* get the interface version */
 	if (!unpack_u32(e, &e->version, "version")) {
-		audit_iface(NULL, NULL, "invalid profile format", e, error);
-		return error;
-	}
+		if (required) {
+			audit_iface(NULL, NULL, "invalid profile format", e,
+				    error);
+			return error;
+		}
 
-	/* check that the interface version is currently supported */
-	if (e->version != 5) {
-		audit_iface(NULL, NULL, "unsupported interface version", e,
-			    error);
-		return error;
+		/* check that the interface version is currently supported */
+		if (e->version != 5) {
+			audit_iface(NULL, NULL, "unsupported interface version",
+				    e, error);
+			return error;
+		}
 	}
 
+
 	/* read the namespace if present */
-	if (!unpack_str(e, ns, "namespace"))
-		*ns = NULL;
+	if (unpack_str(e, &name, "namespace")) {
+		if (*ns && strcmp(*ns, name))
+			audit_iface(NULL, NULL, "invalid ns change", e, error);
+		else if (!*ns)
+			*ns = name;
+	}
 
 	return 0;
 }
@@ -693,18 +707,40 @@ static int verify_profile(struct aa_profile *profile)
 	return 0;
 }
 
+void aa_load_ent_free(struct aa_load_ent *ent)
+{
+	if (ent) {
+		aa_put_profile(ent->rename);
+		aa_put_profile(ent->old);
+		aa_put_profile(ent->new);
+		kzfree(ent);
+	}
+}
+
+struct aa_load_ent *aa_load_ent_alloc(void)
+{
+	struct aa_load_ent *ent = kzalloc(sizeof(*ent), GFP_KERNEL);
+	if (ent)
+		INIT_LIST_HEAD(&ent->list);
+	return ent;
+}
+
 /**
- * aa_unpack - unpack packed binary profile data loaded from user space
+ * aa_unpack - unpack packed binary profile(s) data loaded from user space
  * @udata: user data copied to kmem  (NOT NULL)
  * @size: the size of the user data
+ * @lh: list to place unpacked profiles in a aa_repl_ws
  * @ns: Returns namespace profile is in if specified else NULL (NOT NULL)
  *
- * Unpack user data and return refcounted allocated profile or ERR_PTR
+ * Unpack user data and return refcounted allocated profile(s) stored in
+ * @lh in order of discovery, with the list chain stored in base.list
+ * or error
  *
- * Returns: profile else error pointer if fails to unpack
+ * Returns: profile(s) on @lh else error pointer if fails to unpack
  */
-struct aa_profile *aa_unpack(void *udata, size_t size, const char **ns)
+int aa_unpack(void *udata, size_t size, struct list_head *lh, const char **ns)
 {
+	struct aa_load_ent *tmp, *ent;
 	struct aa_profile *profile = NULL;
 	int error;
 	struct aa_ext e = {
@@ -713,20 +749,42 @@ struct aa_profile *aa_unpack(void *udata, size_t size, const char **ns)
 		.pos = udata,
 	};
 
-	error = verify_header(&e, ns);
-	if (error)
-		return ERR_PTR(error);
+	*ns = NULL;
+	while (e.pos < e.end) {
+		error = verify_header(&e, e.pos == e.start, ns);
+		if (error)
+			goto fail;
 
-	profile = unpack_profile(&e);
-	if (IS_ERR(profile))
-		return profile;
+		profile = unpack_profile(&e);
+		if (IS_ERR(profile)) {
+			error = PTR_ERR(profile);
+			goto fail;
+		}
+
+		error = verify_profile(profile);
+		if (error) {
+			aa_put_profile(profile);
+			goto fail;
+		}
+
+		ent = aa_load_ent_alloc();
+		if (!ent) {
+			error = -ENOMEM;
+			aa_put_profile(profile);
+			goto fail;
+		}
 
-	error = verify_profile(profile);
-	if (error) {
-		aa_put_profile(profile);
-		profile = ERR_PTR(error);
+		ent->new = profile;
+		list_add_tail(&ent->list, lh);
 	}
 
-	/* return refcount */
-	return profile;
+	return 0;
+
+fail:
+	list_for_each_entry_safe(ent, tmp, lh, list) {
+		list_del_init(&ent->list);
+		aa_load_ent_free(ent);
+	}
+
+	return error;
 }