userns: Convert security/keys to the new userns infrastructure

- Replace key_user ->user_ns equality checks with kuid_has_mapping checks.
- Use from_kuid to generate key descriptions
- Use kuid_t and kgid_t and the associated helpers instead of uid_t and gid_t
- Avoid potential problems with file descriptor passing by displaying
  keys in the user namespace of the opener of key status proc files.

Cc: linux-security-module@vger.kernel.org
Cc: keyrings@linux-nfs.org
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

1 files changed, 30 insertions, 20 deletions

diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 3364fbf46807..1ecc0f79906e 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -569,8 +569,8 @@ okay:
 	ret = snprintf(tmpbuf, PAGE_SIZE - 1,
 		       "%s;%d;%d;%08x;%s",
 		       key->type->name,
-		       key->uid,
-		       key->gid,
+		       from_kuid_munged(current_user_ns(), key->uid),
+		       from_kgid_munged(current_user_ns(), key->gid),
 		       key->perm,
 		       key->description ?: "");
 
@@ -766,15 +766,25 @@ error:
  *
  * If successful, 0 will be returned.
  */
-long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid)
+long keyctl_chown_key(key_serial_t id, uid_t user, gid_t group)
 {
 	struct key_user *newowner, *zapowner = NULL;
 	struct key *key;
 	key_ref_t key_ref;
 	long ret;
+	kuid_t uid;
+	kgid_t gid;
+
+	uid = make_kuid(current_user_ns(), user);
+	gid = make_kgid(current_user_ns(), group);
+	ret = -EINVAL;
+	if ((user != (uid_t) -1) && !uid_valid(uid))
+		goto error;
+	if ((group != (gid_t) -1) && !gid_valid(gid))
+		goto error;
 
 	ret = 0;
-	if (uid == (uid_t) -1 && gid == (gid_t) -1)
+	if (user == (uid_t) -1 && group == (gid_t) -1)
 		goto error;
 
 	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
@@ -792,27 +802,27 @@ long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid)
 
 	if (!capable(CAP_SYS_ADMIN)) {
 		/* only the sysadmin can chown a key to some other UID */
-		if (uid != (uid_t) -1 && key->uid != uid)
+		if (user != (uid_t) -1 && !uid_eq(key->uid, uid))
 			goto error_put;
 
 		/* only the sysadmin can set the key's GID to a group other
 		 * than one of those that the current process subscribes to */
-		if (gid != (gid_t) -1 && gid != key->gid && !in_group_p(gid))
+		if (group != (gid_t) -1 && !gid_eq(gid, key->gid) && !in_group_p(gid))
 			goto error_put;
 	}
 
 	/* change the UID */
-	if (uid != (uid_t) -1 && uid != key->uid) {
+	if (user != (uid_t) -1 && !uid_eq(uid, key->uid)) {
 		ret = -ENOMEM;
-		newowner = key_user_lookup(uid, current_user_ns());
+		newowner = key_user_lookup(uid);
 		if (!newowner)
 			goto error_put;
 
 		/* transfer the quota burden to the new user */
 		if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
-			unsigned maxkeys = (uid == 0) ?
+			unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ?
 				key_quota_root_maxkeys : key_quota_maxkeys;
-			unsigned maxbytes = (uid == 0) ?
+			unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
 				key_quota_root_maxbytes : key_quota_maxbytes;
 
 			spin_lock(&newowner->lock);
@@ -846,7 +856,7 @@ long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid)
 	}
 
 	/* change the GID */
-	if (gid != (gid_t) -1)
+	if (group != (gid_t) -1)
 		key->gid = gid;
 
 	ret = 0;
@@ -897,7 +907,7 @@ long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
 	down_write(&key->sem);
 
 	/* if we're not the sysadmin, we can only change a key that we own */
-	if (capable(CAP_SYS_ADMIN) || key->uid == current_fsuid()) {
+	if (capable(CAP_SYS_ADMIN) || uid_eq(key->uid, current_fsuid())) {
 		key->perm = perm;
 		ret = 0;
 	}
@@ -1507,18 +1517,18 @@ long keyctl_session_to_parent(void)
 
 	/* the parent must have the same effective ownership and mustn't be
 	 * SUID/SGID */
-	if (pcred->uid	!= mycred->euid	||
-	    pcred->euid	!= mycred->euid	||
-	    pcred->suid	!= mycred->euid	||
-	    pcred->gid	!= mycred->egid	||
-	    pcred->egid	!= mycred->egid	||
-	    pcred->sgid	!= mycred->egid)
+	if (!uid_eq(pcred->uid,	 mycred->euid) ||
+	    !uid_eq(pcred->euid, mycred->euid) ||
+	    !uid_eq(pcred->suid, mycred->euid) ||
+	    !gid_eq(pcred->gid,	 mycred->egid) ||
+	    !gid_eq(pcred->egid, mycred->egid) ||
+	    !gid_eq(pcred->sgid, mycred->egid))
 		goto unlock;
 
 	/* the keyrings must have the same UID */
 	if ((pcred->tgcred->session_keyring &&
-	     pcred->tgcred->session_keyring->uid != mycred->euid) ||
-	    mycred->tgcred->session_keyring->uid != mycred->euid)
+	     !uid_eq(pcred->tgcred->session_keyring->uid, mycred->euid)) ||
+	    !uid_eq(mycred->tgcred->session_keyring->uid, mycred->euid))
 		goto unlock;
 
 	/* cancel an already pending keyring replacement */