Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

Pull security subsystem fixes from James Morris:
 "Two fixes for the security subsystem:

   - keys: split both rcu_dereference_key() and user_key_payload() into
     versions which can be called with or without holding the key
     semaphore.

   - SELinux: fix Android init(8) breakage due to new cgroup security
     labeling support when using older policy"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  selinux: wrap cgroup seclabel support with its own policy capability
  KEYS: Differentiate uses of rcu_dereference_key() and user_key_payload()

Documentation/security/keys.txt

@@ -1151,8 +1151,21 @@ access the data:
      usage.  This is called key->payload.rcu_data0.  The following accessors
      wrap the RCU calls to this element:
 
+     (a) Set or change the first payload pointer:
+
 		rcu_assign_keypointer(struct key *key, void *data);
-	void *rcu_dereference_key(struct key *key);
+
+     (b) Read the first payload pointer with the key semaphore held:
+
+		[const] void *dereference_key_locked([const] struct key *key);
+
+	 Note that the return value will inherit its constness from the key
+	 parameter.  Static analysis will give an error if it things the lock
+	 isn't held.
+
+     (c) Read the first payload pointer with the RCU read lock held:
+
+		const void *dereference_key_rcu(const struct key *key);
 
 
 ===================

drivers/md/dm-crypt.c

@@ -1536,7 +1536,7 @@ static int crypt_set_keyring_key(struct crypt_config *cc, const char *key_string
 
 	down_read(&key->sem);
 
-	ukp = user_key_payload(key);
+	ukp = user_key_payload_locked(key);
 	if (!ukp) {
 		up_read(&key->sem);
 		key_put(key);

fs/cifs/connect.c

@@ -2455,7 +2455,7 @@ cifs_set_cifscreds(struct smb_vol *vol, struct cifs_ses *ses)
 	}
 
 	down_read(&key->sem);
-	upayload = user_key_payload(key);
+	upayload = user_key_payload_locked(key);
 	if (IS_ERR_OR_NULL(upayload)) {
 		rc = upayload ? PTR_ERR(upayload) : -EINVAL;
 		goto out_key_put;

fs/crypto/keyinfo.c

@@ -103,7 +103,7 @@ static int validate_user_key(struct fscrypt_info *crypt_info,
 		goto out;
 	}
 	down_read(&keyring_key->sem);
-	ukp = user_key_payload(keyring_key);
+	ukp = user_key_payload_locked(keyring_key);
 	if (ukp->datalen != sizeof(struct fscrypt_key)) {
 		res = -EINVAL;
 		up_read(&keyring_key->sem);

fs/ecryptfs/ecryptfs_kernel.h

@@ -117,7 +117,7 @@ ecryptfs_get_key_payload_data(struct key *key)
 
 	auth_tok = ecryptfs_get_encrypted_key_payload_data(key);
 	if (!auth_tok)
-		return (struct ecryptfs_auth_tok *)user_key_payload(key)->data;
+		return (struct ecryptfs_auth_tok *)user_key_payload_locked(key)->data;
 	else
 		return auth_tok;
 }

fs/fscache/object-list.c

@@ -329,7 +329,7 @@ static void fscache_objlist_config(struct fscache_objlist_data *data)
 	config = 0;
 	rcu_read_lock();
 
-	confkey = user_key_payload(key);
+	confkey = user_key_payload_rcu(key);
 	buf = confkey->data;
 
 	for (len = confkey->datalen - 1; len >= 0; len--) {

fs/nfs/nfs4idmap.c

@@ -316,7 +316,7 @@ static ssize_t nfs_idmap_get_key(const char *name, size_t namelen,
 	if (ret < 0)
 		goto out_up;
 
-	payload = user_key_payload(rkey);
+	payload = user_key_payload_rcu(rkey);
 	if (IS_ERR_OR_NULL(payload)) {
 		ret = PTR_ERR(payload);
 		goto out_up;

include/keys/user-type.h

@@ -48,9 +48,14 @@ extern void user_describe(const struct key *user, struct seq_file *m);
 extern long user_read(const struct key *key,
 		      char __user *buffer, size_t buflen);
 
-static inline const struct user_key_payload *user_key_payload(const struct key *key)
+static inline const struct user_key_payload *user_key_payload_rcu(const struct key *key)
 {
-	return (struct user_key_payload *)rcu_dereference_key(key);
+	return (struct user_key_payload *)dereference_key_rcu(key);
+}
+
+static inline struct user_key_payload *user_key_payload_locked(const struct key *key)
+{
+	return (struct user_key_payload *)dereference_key_locked((struct key *)key);
 }
 
 #endif /* CONFIG_KEYS */

include/linux/key.h

@@ -354,7 +354,10 @@ static inline bool key_is_instantiated(const struct key *key)
 		!test_bit(KEY_FLAG_NEGATIVE, &key->flags);
 }
 
-#define rcu_dereference_key(KEY)					\
+#define dereference_key_rcu(KEY)					\
+	(rcu_dereference((KEY)->payload.rcu_data0))
+
+#define dereference_key_locked(KEY)					\
 	(rcu_dereference_protected((KEY)->payload.rcu_data0,		\
 				   rwsem_is_locked(&((struct key *)(KEY))->sem)))
 

lib/digsig.c

@@ -85,7 +85,7 @@ static int digsig_verify_rsa(struct key *key,
 	struct pubkey_hdr *pkh;
 
 	down_read(&key->sem);
-	ukp = user_key_payload(key);
+	ukp = user_key_payload_locked(key);
 
 	if (ukp->datalen < sizeof(*pkh))
 		goto err1;

net/dns_resolver/dns_query.c

@@ -70,7 +70,7 @@ int dns_query(const char *type, const char *name, size_t namelen,
 	      const char *options, char **_result, time64_t *_expiry)
 {
 	struct key *rkey;
-	const struct user_key_payload *upayload;
+	struct user_key_payload *upayload;
 	const struct cred *saved_cred;
 	size_t typelen, desclen;
 	char *desc, *cp;
@@ -141,7 +141,7 @@ int dns_query(const char *type, const char *name, size_t namelen,
 	if (ret)
 		goto put;
 
-	upayload = user_key_payload(rkey);
+	upayload = user_key_payload_locked(rkey);
 	len = upayload->datalen;
 
 	ret = -ENOMEM;

security/keys/dh.c

@@ -55,7 +55,7 @@ static ssize_t mpi_from_key(key_serial_t keyid, size_t maxlen, MPI *mpi)
 		if (status == 0) {
 			const struct user_key_payload *payload;
 
-			payload = user_key_payload(key);
+			payload = user_key_payload_locked(key);
 
 			if (maxlen == 0) {
 				*mpi = NULL;

security/keys/encrypted-keys/encrypted.c

@@ -314,7 +314,7 @@ static struct key *request_user_key(const char *master_desc, const u8 **master_k
 		goto error;
 
 	down_read(&ukey->sem);
-	upayload = user_key_payload(ukey);
+	upayload = user_key_payload_locked(ukey);
 	*master_key = upayload->data;
 	*master_keylen = upayload->datalen;
 error:
@@ -926,7 +926,7 @@ static long encrypted_read(const struct key *key, char __user *buffer,
 	size_t asciiblob_len;
 	int ret;
 
-	epayload = rcu_dereference_key(key);
+	epayload = dereference_key_locked(key);
 
 	/* returns the hex encoded iv, encrypted-data, and hmac as ascii */
 	asciiblob_len = epayload->datablob_len + ivsize + 1

security/keys/trusted.c

@@ -1140,12 +1140,12 @@ out:
 static long trusted_read(const struct key *key, char __user *buffer,
 			 size_t buflen)
 {
-	struct trusted_key_payload *p;
+	const struct trusted_key_payload *p;
 	char *ascii_buf;
 	char *bufp;
 	int i;
 
-	p = rcu_dereference_key(key);
+	p = dereference_key_locked(key);
 	if (!p)
 		return -EINVAL;
 	if (!buffer || buflen <= 0)

security/keys/user_defined.c

@@ -107,7 +107,7 @@ int user_update(struct key *key, struct key_preparsed_payload *prep)
 	/* attach the new data, displacing the old */
 	key->expiry = prep->expiry;
 	if (!test_bit(KEY_FLAG_NEGATIVE, &key->flags))
-		zap = rcu_dereference_key(key);
+		zap = dereference_key_locked(key);
 	rcu_assign_keypointer(key, prep->payload.data[0]);
 	prep->payload.data[0] = NULL;
 
@@ -123,7 +123,7 @@ EXPORT_SYMBOL_GPL(user_update);
  */
 void user_revoke(struct key *key)
 {
-	struct user_key_payload *upayload = key->payload.data[0];
+	struct user_key_payload *upayload = user_key_payload_locked(key);
 
 	/* clear the quota */
 	key_payload_reserve(key, 0);
@@ -169,7 +169,7 @@ long user_read(const struct key *key, char __user *buffer, size_t buflen)
 	const struct user_key_payload *upayload;
 	long ret;
 
-	upayload = user_key_payload(key);
+	upayload = user_key_payload_locked(key);
 	ret = upayload->datalen;
 
 	/* we can return the data as is */

security/selinux/hooks.c

@@ -480,12 +480,13 @@ static int selinux_is_sblabel_mnt(struct super_block *sb)
 		sbsec->behavior == SECURITY_FS_USE_NATIVE ||
 		/* Special handling. Genfs but also in-core setxattr handler */
 		!strcmp(sb->s_type->name, "sysfs") ||
-		!strcmp(sb->s_type->name, "cgroup") ||
-		!strcmp(sb->s_type->name, "cgroup2") ||
 		!strcmp(sb->s_type->name, "pstore") ||
 		!strcmp(sb->s_type->name, "debugfs") ||
 		!strcmp(sb->s_type->name, "tracefs") ||
-		!strcmp(sb->s_type->name, "rootfs");
+		!strcmp(sb->s_type->name, "rootfs") ||
+		(selinux_policycap_cgroupseclabel &&
+		 (!strcmp(sb->s_type->name, "cgroup") ||
+		  !strcmp(sb->s_type->name, "cgroup2")));
 }
 
 static int sb_finish_set_opts(struct super_block *sb)

security/selinux/include/security.h

@@ -71,6 +71,7 @@ enum {
 	POLICYDB_CAPABILITY_OPENPERM,
 	POLICYDB_CAPABILITY_EXTSOCKCLASS,
 	POLICYDB_CAPABILITY_ALWAYSNETWORK,
+	POLICYDB_CAPABILITY_CGROUPSECLABEL,
 	__POLICYDB_CAPABILITY_MAX
 };
 #define POLICYDB_CAPABILITY_MAX (__POLICYDB_CAPABILITY_MAX - 1)
@@ -79,6 +80,7 @@ extern int selinux_policycap_netpeer;
 extern int selinux_policycap_openperm;
 extern int selinux_policycap_extsockclass;
 extern int selinux_policycap_alwaysnetwork;
+extern int selinux_policycap_cgroupseclabel;
 
 /*
  * type_datum properties

security/selinux/selinuxfs.c

@@ -46,7 +46,8 @@ static char *policycap_names[] = {
 	"network_peer_controls",
 	"open_perms",
 	"extended_socket_class",
-	"always_check_network"
+	"always_check_network",
+	"cgroup_seclabel"
 };
 
 unsigned int selinux_checkreqprot = CONFIG_SECURITY_SELINUX_CHECKREQPROT_VALUE;

security/selinux/ss/services.c

@@ -74,6 +74,7 @@ int selinux_policycap_netpeer;
 int selinux_policycap_openperm;
 int selinux_policycap_extsockclass;
 int selinux_policycap_alwaysnetwork;
+int selinux_policycap_cgroupseclabel;
 
 static DEFINE_RWLOCK(policy_rwlock);
 
@@ -1993,6 +1994,9 @@ static void security_load_policycaps(void)
 					  POLICYDB_CAPABILITY_EXTSOCKCLASS);
 	selinux_policycap_alwaysnetwork = ebitmap_get_bit(&policydb.policycaps,
 						  POLICYDB_CAPABILITY_ALWAYSNETWORK);
+	selinux_policycap_cgroupseclabel =
+		ebitmap_get_bit(&policydb.policycaps,
+				POLICYDB_CAPABILITY_CGROUPSECLABEL);
 }
 
 static int security_preserve_bools(struct policydb *p);