keys: distinguish per-uid keys in different namespaces

per-uid keys were looked by uid only.  Use the user namespace
to distinguish the same uid in different namespaces.

This does not address key_permission.  So a task can for instance
try to join a keyring owned by the same uid in another namespace.
That will be handled by a separate patch.

Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

6 files changed, 17 insertions, 6 deletions

diff --git a/kernel/user.c b/kernel/user.c
index 477b6660f447..d8b332c3ae3a 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -20,7 +20,7 @@
 
 struct user_namespace init_user_ns = {
         .kref = {
-                .refcount       = ATOMIC_INIT(1),
+                .refcount       = ATOMIC_INIT(2),
         },
         .creator = &root_user,
 };
diff --git a/security/keys/internal.h b/security/keys/internal.h
index 81932abefe7b..9fb679c66b8a 100644
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -53,6 +53,7 @@ struct key_user {
         atomic_t                nkeys;          /* number of keys */
         atomic_t                nikeys;         /* number of instantiated keys */
         uid_t                   uid;
+        struct user_namespace   *user_ns;
         int                     qnkeys;         /* number of keys allocated to this user */
         int                     qnbytes;        /* number of bytes allocated to this user */
 };
@@ -61,7 +62,8 @@ extern struct rb_root	key_user_tree;
 extern spinlock_t       key_user_lock;
 extern struct key_user  root_key_user;
 
-extern struct key_user *key_user_lookup(uid_t uid);
+extern struct key_user *key_user_lookup(uid_t uid,
+                                        struct user_namespace *user_ns);
 extern void key_user_put(struct key_user *user);
 
 /*
diff --git a/security/keys/key.c b/security/keys/key.c
index f76c8a546fd3..4a1297d1ada4 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -18,6 +18,7 @@
 #include <linux/workqueue.h>
 #include <linux/random.h>
 #include <linux/err.h>
+#include <linux/user_namespace.h>
 #include "internal.h"
 
 static struct kmem_cache        *key_jar;
@@ -60,7 +61,7 @@ void __key_check(const struct key *key)
  * get the key quota record for a user, allocating a new record if one doesn't
  * already exist
  */
-struct key_user *key_user_lookup(uid_t uid)
+struct key_user *key_user_lookup(uid_t uid, struct user_namespace *user_ns)
 {
         struct key_user *candidate = NULL, *user;
         struct rb_node *parent = NULL;
@@ -79,6 +80,10 @@ struct key_user *key_user_lookup(uid_t uid)
                         p = &(*p)->rb_left;
                 else if (uid > user->uid)
                         p = &(*p)->rb_right;
+                else if (user_ns < user->user_ns)
+                        p = &(*p)->rb_left;
+                else if (user_ns > user->user_ns)
+                        p = &(*p)->rb_right;
                 else
                         goto found;
         }
@@ -106,6 +111,7 @@ struct key_user *key_user_lookup(uid_t uid)
         atomic_set(&candidate->nkeys, 0);
         atomic_set(&candidate->nikeys, 0);
         candidate->uid = uid;
+        candidate->user_ns = get_user_ns(user_ns);
         candidate->qnkeys = 0;
         candidate->qnbytes = 0;
         spin_lock_init(&candidate->lock);
@@ -136,6 +142,7 @@ void key_user_put(struct key_user *user)
         if (atomic_dec_and_lock(&user->usage, &key_user_lock)) {
                 rb_erase(&user->node, &key_user_tree);
                 spin_unlock(&key_user_lock);
+                put_user_ns(user->user_ns);
 
                 kfree(user);
         }
@@ -234,7 +241,7 @@ struct key *key_alloc(struct key_type *type, const char *desc,
         quotalen = desclen + type->def_datalen;
 
         /* get hold of the key tracking for this user */
-        user = key_user_lookup(uid);
+        user = key_user_lookup(uid, cred->user->user_ns);
         if (!user)
                 goto no_memory_1;
 
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index b1ec3b4ee17d..7f09fb897d2b 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -726,7 +726,7 @@ long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid)
         /* change the UID */
         if (uid != (uid_t) -1 && uid != key->uid) {
                 ret = -ENOMEM;
-                newowner = key_user_lookup(uid);
+                newowner = key_user_lookup(uid, current_user_ns());
                 if (!newowner)
                         goto error_put;
 
diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index 2f5d89e92b85..276d27882ce8 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -17,6 +17,7 @@
 #include <linux/fs.h>
 #include <linux/err.h>
 #include <linux/mutex.h>
+#include <linux/user_namespace.h>
 #include <asm/uaccess.h>
 #include "internal.h"
 
@@ -34,6 +35,7 @@ struct key_user root_key_user = {
         .nkeys          = ATOMIC_INIT(2),
         .nikeys         = ATOMIC_INIT(2),
         .uid            = 0,
+        .user_ns        = &init_user_ns,
 };
 
 /*****************************************************************************/
diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index 0e04f72ef2d4..22a31582bfaa 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -365,7 +365,7 @@ static struct key *construct_key_and_link(struct key_type *type,
 
         kenter("");
 
-        user = key_user_lookup(current_fsuid());
+        user = key_user_lookup(current_fsuid(), current_user_ns());
         if (!user)
                 return ERR_PTR(-ENOMEM);