[PATCH] keys: sort out key quota system

Add the ability for key creation to overrun the user's quota in some
circumstances - notably when a session keyring is created and assigned to a
process that didn't previously have one.

This means it's still possible to log in, should PAM require the creation of a
new session keyring, and fix an overburdened key quota.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

11 files changed, 85 insertions, 51 deletions

diff --git a/include/linux/key.h b/include/linux/key.h
index e81ebf910d0b..e693e729bc92 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -248,7 +248,14 @@ extern struct key *key_alloc(struct key_type *type,
                              const char *desc,
                              uid_t uid, gid_t gid,
                              struct task_struct *ctx,
-                             key_perm_t perm, int not_in_quota);
+                             key_perm_t perm,
+                             unsigned long flags);
+
+
+#define KEY_ALLOC_IN_QUOTA      0x0000  /* add to quota, reject if would overrun */
+#define KEY_ALLOC_QUOTA_OVERRUN 0x0001  /* add to quota, permit even if overrun */
+#define KEY_ALLOC_NOT_IN_QUOTA  0x0002  /* not in quota */
+
 extern int key_payload_reserve(struct key *key, size_t datalen);
 extern int key_instantiate_and_link(struct key *key,
                                     const void *data,
@@ -285,7 +292,7 @@ extern key_ref_t key_create_or_update(key_ref_t keyring,
                                       const char *description,
                                       const void *payload,
                                       size_t plen,
-                                      int not_in_quota);
+                                      unsigned long flags);
 
 extern int key_update(key_ref_t key,
                       const void *payload,
@@ -299,7 +306,7 @@ extern int key_unlink(struct key *keyring,
 
 extern struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
                                  struct task_struct *ctx,
-                                 int not_in_quota,
+                                 unsigned long flags,
                                  struct key *dest);
 
 extern int keyring_clear(struct key *keyring);
diff --git a/include/linux/security.h b/include/linux/security.h
index d2c17bd91a29..51805806f974 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -862,6 +862,7 @@ struct swap_info_struct;
  *      Permit allocation of a key and assign security data. Note that key does
  *      not have a serial number assigned at this point.
  *      @key points to the key.
+ *      @flags is the allocation flags
  *      Return 0 if permission is granted, -ve error otherwise.
  * @key_free:
  *      Notification of destruction; free security data.
@@ -1324,7 +1325,7 @@ struct security_operations {
 
         /* key management security hooks */
 #ifdef CONFIG_KEYS
-        int (*key_alloc)(struct key *key, struct task_struct *tsk);
+        int (*key_alloc)(struct key *key, struct task_struct *tsk, unsigned long flags);
         void (*key_free)(struct key *key);
         int (*key_permission)(key_ref_t key_ref,
                               struct task_struct *context,
@@ -3040,9 +3041,10 @@ static inline int security_xfrm_policy_lookup(struct xfrm_policy *xp, u32 sk_sid
 #ifdef CONFIG_KEYS
 #ifdef CONFIG_SECURITY
 static inline int security_key_alloc(struct key *key,
-                                     struct task_struct *tsk)
+                                     struct task_struct *tsk,
+                                     unsigned long flags)
 {
-        return security_ops->key_alloc(key, tsk);
+        return security_ops->key_alloc(key, tsk, flags);
 }
 
 static inline void security_key_free(struct key *key)
@@ -3060,7 +3062,8 @@ static inline int security_key_permission(key_ref_t key_ref,
 #else
 
 static inline int security_key_alloc(struct key *key,
-                                     struct task_struct *tsk)
+                                     struct task_struct *tsk,
+                                     unsigned long flags)
 {
         return 0;
 }
diff --git a/security/dummy.c b/security/dummy.c
index c3c5493581e2..310fcdf7b749 100644
--- a/security/dummy.c
+++ b/security/dummy.c
@@ -870,7 +870,8 @@ static int dummy_setprocattr(struct task_struct *p, char *name, void *value, siz
 }
 
 #ifdef CONFIG_KEYS
-static inline int dummy_key_alloc(struct key *key, struct task_struct *ctx)
+static inline int dummy_key_alloc(struct key *key, struct task_struct *ctx,
+                                  unsigned long flags)
 {
         return 0;
 }
diff --git a/security/keys/internal.h b/security/keys/internal.h
index e066e6057955..3c2877f0663e 100644
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -99,7 +99,8 @@ extern int install_process_keyring(struct task_struct *tsk);
 extern struct key *request_key_and_link(struct key_type *type,
                                         const char *description,
                                         const char *callout_info,
-                                        struct key *dest_keyring);
+                                        struct key *dest_keyring,
+                                        unsigned long flags);
 
 /*
  * request_key authorisation
diff --git a/security/keys/key.c b/security/keys/key.c
index 51f851557389..3601fddca9f2 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -248,7 +248,7 @@ static inline void key_alloc_serial(struct key *key)
  */
 struct key *key_alloc(struct key_type *type, const char *desc,
                       uid_t uid, gid_t gid, struct task_struct *ctx,
-                      key_perm_t perm, int not_in_quota)
+                      key_perm_t perm, unsigned long flags)
 {
         struct key_user *user = NULL;
         struct key *key;
@@ -269,12 +269,14 @@ struct key *key_alloc(struct key_type *type, const char *desc,
 
         /* check that the user's quota permits allocation of another key and
          * its description */
-        if (!not_in_quota) {
+        if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
                 spin_lock(&user->lock);
-                if (user->qnkeys + 1 >= KEYQUOTA_MAX_KEYS ||
-                    user->qnbytes + quotalen >= KEYQUOTA_MAX_BYTES
-                    )
-                        goto no_quota;
+                if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
+                        if (user->qnkeys + 1 >= KEYQUOTA_MAX_KEYS ||
+                            user->qnbytes + quotalen >= KEYQUOTA_MAX_BYTES
+                            )
+                                goto no_quota;
+                }
 
                 user->qnkeys++;
                 user->qnbytes += quotalen;
@@ -308,7 +310,7 @@ struct key *key_alloc(struct key_type *type, const char *desc,
         key->payload.data = NULL;
         key->security = NULL;
 
-        if (!not_in_quota)
+        if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
                 key->flags |= 1 << KEY_FLAG_IN_QUOTA;
 
         memset(&key->type_data, 0, sizeof(key->type_data));
@@ -318,7 +320,7 @@ struct key *key_alloc(struct key_type *type, const char *desc,
 #endif
 
         /* let the security module know about the key */
-        ret = security_key_alloc(key, ctx);
+        ret = security_key_alloc(key, ctx, flags);
         if (ret < 0)
                 goto security_error;
 
@@ -332,7 +334,7 @@ error:
 security_error:
         kfree(key->description);
         kmem_cache_free(key_jar, key);
-        if (!not_in_quota) {
+        if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
                 spin_lock(&user->lock);
                 user->qnkeys--;
                 user->qnbytes -= quotalen;
@@ -345,7 +347,7 @@ security_error:
 no_memory_3:
         kmem_cache_free(key_jar, key);
 no_memory_2:
-        if (!not_in_quota) {
+        if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
                 spin_lock(&user->lock);
                 user->qnkeys--;
                 user->qnbytes -= quotalen;
@@ -761,7 +763,7 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref,
                                const char *description,
                                const void *payload,
                                size_t plen,
-                               int not_in_quota)
+                               unsigned long flags)
 {
         struct key_type *ktype;
         struct key *keyring, *key = NULL;
@@ -822,7 +824,7 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref,
 
         /* allocate a new key */
         key = key_alloc(ktype, description, current->fsuid, current->fsgid,
-                        current, perm, not_in_quota);
+                        current, perm, flags);
         if (IS_ERR(key)) {
                 key_ref = ERR_PTR(PTR_ERR(key));
                 goto error_3;
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index ed71d86d2ce2..d74458522e98 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -102,7 +102,7 @@ asmlinkage long sys_add_key(const char __user *_type,
         /* create or update the requested key and add it to the target
          * keyring */
         key_ref = key_create_or_update(keyring_ref, type, description,
-                                       payload, plen, 0);
+                                       payload, plen, KEY_ALLOC_IN_QUOTA);
         if (!IS_ERR(key_ref)) {
                 ret = key_ref_to_ptr(key_ref)->serial;
                 key_ref_put(key_ref);
@@ -184,7 +184,8 @@ asmlinkage long sys_request_key(const char __user *_type,
 
         /* do the search */
         key = request_key_and_link(ktype, description, callout_info,
-                                   key_ref_to_ptr(dest_ref));
+                                   key_ref_to_ptr(dest_ref),
+                                   KEY_ALLOC_IN_QUOTA);
         if (IS_ERR(key)) {
                 ret = PTR_ERR(key);
                 goto error5;
diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index 1357207fc9df..6c282bd937e2 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -240,7 +240,7 @@ static long keyring_read(const struct key *keyring,
  * allocate a keyring and link into the destination keyring
  */
 struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
-                          struct task_struct *ctx, int not_in_quota,
+                          struct task_struct *ctx, unsigned long flags,
                           struct key *dest)
 {
         struct key *keyring;
@@ -249,7 +249,7 @@ struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
         keyring = key_alloc(&key_type_keyring, description,
                             uid, gid, ctx,
                             (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
-                            not_in_quota);
+                            flags);
 
         if (!IS_ERR(keyring)) {
                 ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index 4d9825f9962c..32150cf7c37f 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -77,7 +77,8 @@ int alloc_uid_keyring(struct user_struct *user,
         /* concoct a default session keyring */
         sprintf(buf, "_uid_ses.%u", user->uid);
 
-        session_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, ctx, 0, NULL);
+        session_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, ctx,
+                                        KEY_ALLOC_IN_QUOTA, NULL);
         if (IS_ERR(session_keyring)) {
                 ret = PTR_ERR(session_keyring);
                 goto error;
@@ -87,8 +88,8 @@ int alloc_uid_keyring(struct user_struct *user,
          * keyring */
         sprintf(buf, "_uid.%u", user->uid);
 
-        uid_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, ctx, 0,
-                                    session_keyring);
+        uid_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, ctx,
+                                    KEY_ALLOC_IN_QUOTA, session_keyring);
         if (IS_ERR(uid_keyring)) {
                 key_put(session_keyring);
                 ret = PTR_ERR(uid_keyring);
@@ -144,7 +145,8 @@ int install_thread_keyring(struct task_struct *tsk)
 
         sprintf(buf, "_tid.%u", tsk->pid);
 
-        keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk, 1, NULL);
+        keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk,
+                                KEY_ALLOC_QUOTA_OVERRUN, NULL);
         if (IS_ERR(keyring)) {
                 ret = PTR_ERR(keyring);
                 goto error;
@@ -178,7 +180,8 @@ int install_process_keyring(struct task_struct *tsk)
         if (!tsk->signal->process_keyring) {
                 sprintf(buf, "_pid.%u", tsk->tgid);
 
-                keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk, 1, NULL);
+                keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk,
+                                        KEY_ALLOC_QUOTA_OVERRUN, NULL);
                 if (IS_ERR(keyring)) {
                         ret = PTR_ERR(keyring);
                         goto error;
@@ -209,6 +212,7 @@ error:
 static int install_session_keyring(struct task_struct *tsk,
                                    struct key *keyring)
 {
+        unsigned long flags;
         struct key *old;
         char buf[20];
 
@@ -218,7 +222,12 @@ static int install_session_keyring(struct task_struct *tsk,
         if (!keyring) {
                 sprintf(buf, "_ses.%u", tsk->tgid);
 
-                keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk, 1, NULL);
+                flags = KEY_ALLOC_QUOTA_OVERRUN;
+                if (tsk->signal->session_keyring)
+                        flags = KEY_ALLOC_IN_QUOTA;
+
+                keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk,
+                                        flags, NULL);
                 if (IS_ERR(keyring))
                         return PTR_ERR(keyring);
         }
@@ -728,7 +737,8 @@ long join_session_keyring(const char *name)
         keyring = find_keyring_by_name(name, 0);
         if (PTR_ERR(keyring) == -ENOKEY) {
                 /* not found - try and create a new one */
-                keyring = keyring_alloc(name, tsk->uid, tsk->gid, tsk, 0, NULL);
+                keyring = keyring_alloc(name, tsk->uid, tsk->gid, tsk,
+                                        KEY_ALLOC_IN_QUOTA, NULL);
                 if (IS_ERR(keyring)) {
                         ret = PTR_ERR(keyring);
                         goto error2;
diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index eab66a06ca53..58d1efd4fc2c 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -48,8 +48,8 @@ static int call_sbin_request_key(struct key *key,
         /* allocate a new session keyring */
         sprintf(desc, "_req.%u", key->serial);
 
-        keyring = keyring_alloc(desc, current->fsuid, current->fsgid,
-                                current, 1, NULL);
+        keyring = keyring_alloc(desc, current->fsuid, current->fsgid, current,
+                                KEY_ALLOC_QUOTA_OVERRUN, NULL);
         if (IS_ERR(keyring)) {
                 ret = PTR_ERR(keyring);
                 goto error_alloc;
@@ -126,7 +126,8 @@ error_alloc:
  */
 static struct key *__request_key_construction(struct key_type *type,
                                               const char *description,
-                                              const char *callout_info)
+                                              const char *callout_info,
+                                              unsigned long flags)
 {
         request_key_actor_t actor;
         struct key_construction cons;
@@ -134,12 +135,12 @@ static struct key *__request_key_construction(struct key_type *type,
         struct key *key, *authkey;
         int ret, negated;
 
-        kenter("%s,%s,%s", type->name, description, callout_info);
+        kenter("%s,%s,%s,%lx", type->name, description, callout_info, flags);
 
         /* create a key and add it to the queue */
         key = key_alloc(type, description,
-                        current->fsuid, current->fsgid,
-                        current, KEY_POS_ALL, 0);
+                        current->fsuid, current->fsgid, current, KEY_POS_ALL,
+                        flags);
         if (IS_ERR(key))
                 goto alloc_failed;
 
@@ -258,15 +259,16 @@ alloc_failed:
 static struct key *request_key_construction(struct key_type *type,
                                             const char *description,
                                             struct key_user *user,
-                                            const char *callout_info)
+                                            const char *callout_info,
+                                            unsigned long flags)
 {
         struct key_construction *pcons;
         struct key *key, *ckey;
 
         DECLARE_WAITQUEUE(myself, current);
 
-        kenter("%s,%s,{%d},%s",
-               type->name, description, user->uid, callout_info);
+        kenter("%s,%s,{%d},%s,%lx",
+               type->name, description, user->uid, callout_info, flags);
 
         /* see if there's such a key under construction already */
         down_write(&key_construction_sem);
@@ -282,7 +284,8 @@ static struct key *request_key_construction(struct key_type *type,
         }
 
         /* see about getting userspace to construct the key */
-        key = __request_key_construction(type, description, callout_info);
+        key = __request_key_construction(type, description, callout_info,
+                                         flags);
  error:
         kleave(" = %p", key);
         return key;
@@ -389,14 +392,15 @@ static void request_key_link(struct key *key, struct key *dest_keyring)
 struct key *request_key_and_link(struct key_type *type,
                                  const char *description,
                                  const char *callout_info,
-                                 struct key *dest_keyring)
+                                 struct key *dest_keyring,
+                                 unsigned long flags)
 {
         struct key_user *user;
         struct key *key;
         key_ref_t key_ref;
 
-        kenter("%s,%s,%s,%p",
-               type->name, description, callout_info, dest_keyring);
+        kenter("%s,%s,%s,%p,%lx",
+               type->name, description, callout_info, dest_keyring, flags);
 
         /* search all the process keyrings for a key */
         key_ref = search_process_keyrings(type, description, type->match,
@@ -429,7 +433,8 @@ struct key *request_key_and_link(struct key_type *type,
                         /* ask userspace (returns NULL if it waited on a key
                          * being constructed) */
                         key = request_key_construction(type, description,
-                                                       user, callout_info);
+                                                       user, callout_info,
+                                                       flags);
                         if (key)
                                 break;
 
@@ -485,7 +490,8 @@ struct key *request_key(struct key_type *type,
                         const char *description,
                         const char *callout_info)
 {
-        return request_key_and_link(type, description, callout_info, NULL);
+        return request_key_and_link(type, description, callout_info, NULL,
+                                    KEY_ALLOC_IN_QUOTA);
 
 } /* end request_key() */
 
diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_auth.c
index cb9817ced3fd..cbf58a91b00a 100644
--- a/security/keys/request_key_auth.c
+++ b/security/keys/request_key_auth.c
@@ -187,7 +187,7 @@ struct key *request_key_auth_new(struct key *target, const char *callout_info)
         authkey = key_alloc(&key_type_request_key_auth, desc,
                             current->fsuid, current->fsgid, current,
                             KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH |
-                            KEY_USR_VIEW, 1);
+                            KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA);
         if (IS_ERR(authkey)) {
                 ret = PTR_ERR(authkey);
                 goto error_alloc;
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 79c16e31c884..13384fef0d60 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -4264,7 +4264,8 @@ static int selinux_setprocattr(struct task_struct *p,
 
 #ifdef CONFIG_KEYS
 
-static int selinux_key_alloc(struct key *k, struct task_struct *tsk)
+static int selinux_key_alloc(struct key *k, struct task_struct *tsk,
+                             unsigned long flags)
 {
         struct task_security_struct *tsec = tsk->security;
         struct key_security_struct *ksec;
@@ -4513,8 +4514,10 @@ static __init int selinux_init(void)
 
 #ifdef CONFIG_KEYS
         /* Add security information to initial keyrings */
-        security_key_alloc(&root_user_keyring, current);
-        security_key_alloc(&root_session_keyring, current);
+        security_key_alloc(&root_user_keyring, current,
+                           KEY_ALLOC_NOT_IN_QUOTA);
+        security_key_alloc(&root_session_keyring, current,
+                           KEY_ALLOC_NOT_IN_QUOTA);
 #endif
 
         return 0;