[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>

7 files changed, 60 insertions, 40 deletions

diff --git a/security/keys/internal.h b/security/keys/internal.h
index e066e60..3c2877f 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 51f8515..3601fdd 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 ed71d86..d744585 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 1357207..6c282bd 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 4d9825f..32150cf 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 eab66a0..58d1efd 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 cb9817c..cbf58a9 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;