string: factorize skip_spaces and export it to be generally available
[safe/jmp/linux-2.6] / security / keys / keyctl.c
index 56e963b..06ec722 100644 (file)
@@ -54,11 +54,11 @@ static int key_get_type_from_user(char *type,
  * - returns the new key's serial number
  * - implements add_key()
  */
-asmlinkage long sys_add_key(const char __user *_type,
-                           const char __user *_description,
-                           const void __user *_payload,
-                           size_t plen,
-                           key_serial_t ringid)
+SYSCALL_DEFINE5(add_key, const char __user *, _type,
+               const char __user *, _description,
+               const void __user *, _payload,
+               size_t, plen,
+               key_serial_t, ringid)
 {
        key_ref_t keyring_ref, key_ref;
        char type[32], *description;
@@ -103,7 +103,7 @@ asmlinkage long sys_add_key(const char __user *_type,
        }
 
        /* find the target keyring (which must be writable) */
-       keyring_ref = lookup_user_key(NULL, ringid, 1, 0, KEY_WRITE);
+       keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
        if (IS_ERR(keyring_ref)) {
                ret = PTR_ERR(keyring_ref);
                goto error3;
@@ -112,7 +112,8 @@ 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, KEY_ALLOC_IN_QUOTA);
+                                      payload, plen, KEY_PERM_UNDEF,
+                                      KEY_ALLOC_IN_QUOTA);
        if (!IS_ERR(key_ref)) {
                ret = key_ref_to_ptr(key_ref)->serial;
                key_ref_put(key_ref);
@@ -145,10 +146,10 @@ asmlinkage long sys_add_key(const char __user *_type,
  *   - if the _callout_info string is empty, it will be rendered as "-"
  * - implements request_key()
  */
-asmlinkage long sys_request_key(const char __user *_type,
-                               const char __user *_description,
-                               const char __user *_callout_info,
-                               key_serial_t destringid)
+SYSCALL_DEFINE4(request_key, const char __user *, _type,
+               const char __user *, _description,
+               const char __user *, _callout_info,
+               key_serial_t, destringid)
 {
        struct key_type *ktype;
        struct key *key;
@@ -184,7 +185,8 @@ asmlinkage long sys_request_key(const char __user *_type,
        /* get the destination keyring if specified */
        dest_ref = NULL;
        if (destringid) {
-               dest_ref = lookup_user_key(NULL, destringid, 1, 0, KEY_WRITE);
+               dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
+                                          KEY_WRITE);
                if (IS_ERR(dest_ref)) {
                        ret = PTR_ERR(dest_ref);
                        goto error3;
@@ -232,9 +234,11 @@ asmlinkage long sys_request_key(const char __user *_type,
 long keyctl_get_keyring_ID(key_serial_t id, int create)
 {
        key_ref_t key_ref;
+       unsigned long lflags;
        long ret;
 
-       key_ref = lookup_user_key(NULL, id, create, 0, KEY_SEARCH);
+       lflags = create ? KEY_LOOKUP_CREATE : 0;
+       key_ref = lookup_user_key(id, lflags, KEY_SEARCH);
        if (IS_ERR(key_ref)) {
                ret = PTR_ERR(key_ref);
                goto error;
@@ -269,6 +273,7 @@ long keyctl_join_session_keyring(const char __user *_name)
 
        /* join the session */
        ret = join_session_keyring(name);
+       kfree(name);
 
  error:
        return ret;
@@ -307,7 +312,7 @@ long keyctl_update_key(key_serial_t id,
        }
 
        /* find the target key (which must be writable) */
-       key_ref = lookup_user_key(NULL, id, 0, 0, KEY_WRITE);
+       key_ref = lookup_user_key(id, 0, KEY_WRITE);
        if (IS_ERR(key_ref)) {
                ret = PTR_ERR(key_ref);
                goto error2;
@@ -335,10 +340,16 @@ long keyctl_revoke_key(key_serial_t id)
        key_ref_t key_ref;
        long ret;
 
-       key_ref = lookup_user_key(NULL, id, 0, 0, KEY_WRITE);
+       key_ref = lookup_user_key(id, 0, KEY_WRITE);
        if (IS_ERR(key_ref)) {
                ret = PTR_ERR(key_ref);
-               goto error;
+               if (ret != -EACCES)
+                       goto error;
+               key_ref = lookup_user_key(id, 0, KEY_SETATTR);
+               if (IS_ERR(key_ref)) {
+                       ret = PTR_ERR(key_ref);
+                       goto error;
+               }
        }
 
        key_revoke(key_ref_to_ptr(key_ref));
@@ -361,7 +372,7 @@ long keyctl_keyring_clear(key_serial_t ringid)
        key_ref_t keyring_ref;
        long ret;
 
-       keyring_ref = lookup_user_key(NULL, ringid, 1, 0, KEY_WRITE);
+       keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
        if (IS_ERR(keyring_ref)) {
                ret = PTR_ERR(keyring_ref);
                goto error;
@@ -387,13 +398,13 @@ long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
        key_ref_t keyring_ref, key_ref;
        long ret;
 
-       keyring_ref = lookup_user_key(NULL, ringid, 1, 0, KEY_WRITE);
+       keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
        if (IS_ERR(keyring_ref)) {
                ret = PTR_ERR(keyring_ref);
                goto error;
        }
 
-       key_ref = lookup_user_key(NULL, id, 1, 0, KEY_LINK);
+       key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_LINK);
        if (IS_ERR(key_ref)) {
                ret = PTR_ERR(key_ref);
                goto error2;
@@ -421,13 +432,13 @@ long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
        key_ref_t keyring_ref, key_ref;
        long ret;
 
-       keyring_ref = lookup_user_key(NULL, ringid, 0, 0, KEY_WRITE);
+       keyring_ref = lookup_user_key(ringid, 0, KEY_WRITE);
        if (IS_ERR(keyring_ref)) {
                ret = PTR_ERR(keyring_ref);
                goto error;
        }
 
-       key_ref = lookup_user_key(NULL, id, 0, 0, 0);
+       key_ref = lookup_user_key(id, KEY_LOOKUP_FOR_UNLINK, 0);
        if (IS_ERR(key_ref)) {
                ret = PTR_ERR(key_ref);
                goto error2;
@@ -463,7 +474,7 @@ long keyctl_describe_key(key_serial_t keyid,
        char *tmpbuf;
        long ret;
 
-       key_ref = lookup_user_key(NULL, keyid, 0, 1, KEY_VIEW);
+       key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_VIEW);
        if (IS_ERR(key_ref)) {
                /* viewing a key under construction is permitted if we have the
                 * authorisation token handy */
@@ -471,8 +482,9 @@ long keyctl_describe_key(key_serial_t keyid,
                        instkey = key_get_instantiation_authkey(keyid);
                        if (!IS_ERR(instkey)) {
                                key_put(instkey);
-                               key_ref = lookup_user_key(NULL, keyid,
-                                                         0, 1, 0);
+                               key_ref = lookup_user_key(keyid,
+                                                         KEY_LOOKUP_PARTIAL,
+                                                         0);
                                if (!IS_ERR(key_ref))
                                        goto okay;
                        }
@@ -556,7 +568,7 @@ long keyctl_keyring_search(key_serial_t ringid,
        }
 
        /* get the keyring at which to begin the search */
-       keyring_ref = lookup_user_key(NULL, ringid, 0, 0, KEY_SEARCH);
+       keyring_ref = lookup_user_key(ringid, 0, KEY_SEARCH);
        if (IS_ERR(keyring_ref)) {
                ret = PTR_ERR(keyring_ref);
                goto error2;
@@ -565,7 +577,8 @@ long keyctl_keyring_search(key_serial_t ringid,
        /* get the destination keyring if specified */
        dest_ref = NULL;
        if (destringid) {
-               dest_ref = lookup_user_key(NULL, destringid, 1, 0, KEY_WRITE);
+               dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
+                                          KEY_WRITE);
                if (IS_ERR(dest_ref)) {
                        ret = PTR_ERR(dest_ref);
                        goto error3;
@@ -635,7 +648,7 @@ long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
        long ret;
 
        /* find the key first */
-       key_ref = lookup_user_key(NULL, keyid, 0, 0, 0);
+       key_ref = lookup_user_key(keyid, 0, 0);
        if (IS_ERR(key_ref)) {
                ret = -ENOKEY;
                goto error;
@@ -698,7 +711,8 @@ long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid)
        if (uid == (uid_t) -1 && gid == (gid_t) -1)
                goto error;
 
-       key_ref = lookup_user_key(NULL, id, 1, 1, KEY_SETATTR);
+       key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
+                                 KEY_SETATTR);
        if (IS_ERR(key_ref)) {
                ret = PTR_ERR(key_ref);
                goto error;
@@ -724,16 +738,22 @@ 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;
 
                /* transfer the quota burden to the new user */
                if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
+                       unsigned maxkeys = (uid == 0) ?
+                               key_quota_root_maxkeys : key_quota_maxkeys;
+                       unsigned maxbytes = (uid == 0) ?
+                               key_quota_root_maxbytes : key_quota_maxbytes;
+
                        spin_lock(&newowner->lock);
-                       if (newowner->qnkeys + 1 >= KEYQUOTA_MAX_KEYS ||
-                           newowner->qnbytes + key->quotalen >=
-                           KEYQUOTA_MAX_BYTES)
+                       if (newowner->qnkeys + 1 >= maxkeys ||
+                           newowner->qnbytes + key->quotalen >= maxbytes ||
+                           newowner->qnbytes + key->quotalen <
+                           newowner->qnbytes)
                                goto quota_overrun;
 
                        newowner->qnkeys++;
@@ -797,7 +817,8 @@ long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
        if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
                goto error;
 
-       key_ref = lookup_user_key(NULL, id, 1, 1, KEY_SETATTR);
+       key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
+                                 KEY_SETATTR);
        if (IS_ERR(key_ref)) {
                ret = PTR_ERR(key_ref);
                goto error;
@@ -810,7 +831,7 @@ 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) || key->uid == current_fsuid()) {
                key->perm = perm;
                ret = 0;
        }
@@ -822,6 +843,60 @@ error:
 
 } /* end keyctl_setperm_key() */
 
+/*
+ * get the destination keyring for instantiation
+ */
+static long get_instantiation_keyring(key_serial_t ringid,
+                                     struct request_key_auth *rka,
+                                     struct key **_dest_keyring)
+{
+       key_ref_t dkref;
+
+       *_dest_keyring = NULL;
+
+       /* just return a NULL pointer if we weren't asked to make a link */
+       if (ringid == 0)
+               return 0;
+
+       /* if a specific keyring is nominated by ID, then use that */
+       if (ringid > 0) {
+               dkref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
+               if (IS_ERR(dkref))
+                       return PTR_ERR(dkref);
+               *_dest_keyring = key_ref_to_ptr(dkref);
+               return 0;
+       }
+
+       if (ringid == KEY_SPEC_REQKEY_AUTH_KEY)
+               return -EINVAL;
+
+       /* otherwise specify the destination keyring recorded in the
+        * authorisation key (any KEY_SPEC_*_KEYRING) */
+       if (ringid >= KEY_SPEC_REQUESTOR_KEYRING) {
+               *_dest_keyring = key_get(rka->dest_keyring);
+               return 0;
+       }
+
+       return -ENOKEY;
+}
+
+/*
+ * change the request_key authorisation key on the current process
+ */
+static int keyctl_change_reqkey_auth(struct key *key)
+{
+       struct cred *new;
+
+       new = prepare_creds();
+       if (!new)
+               return -ENOMEM;
+
+       key_put(new->request_key_auth);
+       new->request_key_auth = key_get(key);
+
+       return commit_creds(new);
+}
+
 /*****************************************************************************/
 /*
  * instantiate the key with the specified payload, and, if one is given, link
@@ -832,13 +907,15 @@ long keyctl_instantiate_key(key_serial_t id,
                            size_t plen,
                            key_serial_t ringid)
 {
+       const struct cred *cred = current_cred();
        struct request_key_auth *rka;
-       struct key *instkey;
-       key_ref_t keyring_ref;
+       struct key *instkey, *dest_keyring;
        void *payload;
        long ret;
        bool vm = false;
 
+       kenter("%d,,%zu,%d", id, plen, ringid);
+
        ret = -EINVAL;
        if (plen > 1024 * 1024 - 1)
                goto error;
@@ -846,7 +923,7 @@ long keyctl_instantiate_key(key_serial_t id,
        /* the appropriate instantiation authorisation key must have been
         * assumed before calling this */
        ret = -EPERM;
-       instkey = current->request_key_auth;
+       instkey = cred->request_key_auth;
        if (!instkey)
                goto error;
 
@@ -876,28 +953,20 @@ long keyctl_instantiate_key(key_serial_t id,
 
        /* find the destination keyring amongst those belonging to the
         * requesting task */
-       keyring_ref = NULL;
-       if (ringid) {
-               keyring_ref = lookup_user_key(rka->context, ringid, 1, 0,
-                                             KEY_WRITE);
-               if (IS_ERR(keyring_ref)) {
-                       ret = PTR_ERR(keyring_ref);
-                       goto error2;
-               }
-       }
+       ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
+       if (ret < 0)
+               goto error2;
 
        /* instantiate the key and link it into a keyring */
        ret = key_instantiate_and_link(rka->target_key, payload, plen,
-                                      key_ref_to_ptr(keyring_ref), instkey);
+                                      dest_keyring, instkey);
 
-       key_ref_put(keyring_ref);
+       key_put(dest_keyring);
 
        /* discard the assumed authority if it's just been disabled by
         * instantiation of the key */
-       if (ret == 0) {
-               key_put(current->request_key_auth);
-               current->request_key_auth = NULL;
-       }
+       if (ret == 0)
+               keyctl_change_reqkey_auth(NULL);
 
 error2:
        if (!vm)
@@ -916,15 +985,17 @@ error:
  */
 long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
 {
+       const struct cred *cred = current_cred();
        struct request_key_auth *rka;
-       struct key *instkey;
-       key_ref_t keyring_ref;
+       struct key *instkey, *dest_keyring;
        long ret;
 
+       kenter("%d,%u,%d", id, timeout, ringid);
+
        /* the appropriate instantiation authorisation key must have been
         * assumed before calling this */
        ret = -EPERM;
-       instkey = current->request_key_auth;
+       instkey = cred->request_key_auth;
        if (!instkey)
                goto error;
 
@@ -934,27 +1005,20 @@ long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
 
        /* find the destination keyring if present (which must also be
         * writable) */
-       keyring_ref = NULL;
-       if (ringid) {
-               keyring_ref = lookup_user_key(NULL, ringid, 1, 0, KEY_WRITE);
-               if (IS_ERR(keyring_ref)) {
-                       ret = PTR_ERR(keyring_ref);
-                       goto error;
-               }
-       }
+       ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
+       if (ret < 0)
+               goto error;
 
        /* instantiate the key and link it into a keyring */
        ret = key_negate_and_link(rka->target_key, timeout,
-                                 key_ref_to_ptr(keyring_ref), instkey);
+                                 dest_keyring, instkey);
 
-       key_ref_put(keyring_ref);
+       key_put(dest_keyring);
 
        /* discard the assumed authority if it's just been disabled by
         * instantiation of the key */
-       if (ret == 0) {
-               key_put(current->request_key_auth);
-               current->request_key_auth = NULL;
-       }
+       if (ret == 0)
+               keyctl_change_reqkey_auth(NULL);
 
 error:
        return ret;
@@ -968,35 +1032,56 @@ error:
  */
 long keyctl_set_reqkey_keyring(int reqkey_defl)
 {
-       int ret;
+       struct cred *new;
+       int ret, old_setting;
+
+       old_setting = current_cred_xxx(jit_keyring);
+
+       if (reqkey_defl == KEY_REQKEY_DEFL_NO_CHANGE)
+               return old_setting;
+
+       new = prepare_creds();
+       if (!new)
+               return -ENOMEM;
 
        switch (reqkey_defl) {
        case KEY_REQKEY_DEFL_THREAD_KEYRING:
-               ret = install_thread_keyring(current);
+               ret = install_thread_keyring_to_cred(new);
                if (ret < 0)
-                       return ret;
+                       goto error;
                goto set;
 
        case KEY_REQKEY_DEFL_PROCESS_KEYRING:
-               ret = install_process_keyring(current);
-               if (ret < 0)
-                       return ret;
+               ret = install_process_keyring_to_cred(new);
+               if (ret < 0) {
+                       if (ret != -EEXIST)
+                               goto error;
+                       ret = 0;
+               }
+               goto set;
 
        case KEY_REQKEY_DEFL_DEFAULT:
        case KEY_REQKEY_DEFL_SESSION_KEYRING:
        case KEY_REQKEY_DEFL_USER_KEYRING:
        case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
-       set:
-               current->jit_keyring = reqkey_defl;
+       case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
+               goto set;
 
        case KEY_REQKEY_DEFL_NO_CHANGE:
-               return current->jit_keyring;
-
        case KEY_REQKEY_DEFL_GROUP_KEYRING:
        default:
-               return -EINVAL;
+               ret = -EINVAL;
+               goto error;
        }
 
+set:
+       new->jit_keyring = reqkey_defl;
+       commit_creds(new);
+       return old_setting;
+error:
+       abort_creds(new);
+       return -EINVAL;
+
 } /* end keyctl_set_reqkey_keyring() */
 
 /*****************************************************************************/
@@ -1011,7 +1096,8 @@ long keyctl_set_timeout(key_serial_t id, unsigned timeout)
        time_t expiry;
        long ret;
 
-       key_ref = lookup_user_key(NULL, id, 1, 1, KEY_SETATTR);
+       key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
+                                 KEY_SETATTR);
        if (IS_ERR(key_ref)) {
                ret = PTR_ERR(key_ref);
                goto error;
@@ -1029,6 +1115,7 @@ long keyctl_set_timeout(key_serial_t id, unsigned timeout)
        }
 
        key->expiry = expiry;
+       key_schedule_gc(key->expiry + key_gc_delay);
 
        up_write(&key->sem);
        key_put(key);
@@ -1055,9 +1142,7 @@ long keyctl_assume_authority(key_serial_t id)
 
        /* we divest ourselves of authority if given an ID of 0 */
        if (id == 0) {
-               key_put(current->request_key_auth);
-               current->request_key_auth = NULL;
-               ret = 0;
+               ret = keyctl_change_reqkey_auth(NULL);
                goto error;
        }
 
@@ -1072,10 +1157,12 @@ long keyctl_assume_authority(key_serial_t id)
                goto error;
        }
 
-       key_put(current->request_key_auth);
-       current->request_key_auth = authkey;
-       ret = authkey->serial;
+       ret = keyctl_change_reqkey_auth(authkey);
+       if (ret < 0)
+               goto error;
+       key_put(authkey);
 
+       ret = authkey->serial;
 error:
        return ret;
 
@@ -1098,7 +1185,7 @@ long keyctl_get_security(key_serial_t keyid,
        char *context;
        long ret;
 
-       key_ref = lookup_user_key(NULL, keyid, 0, 1, KEY_VIEW);
+       key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_VIEW);
        if (IS_ERR(key_ref)) {
                if (PTR_ERR(key_ref) != -EACCES)
                        return PTR_ERR(key_ref);
@@ -1110,7 +1197,7 @@ long keyctl_get_security(key_serial_t keyid,
                        return PTR_ERR(key_ref);
                key_put(instkey);
 
-               key_ref = lookup_user_key(NULL, keyid, 0, 1, 0);
+               key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, 0);
                if (IS_ERR(key_ref))
                        return PTR_ERR(key_ref);
        }
@@ -1141,12 +1228,112 @@ long keyctl_get_security(key_serial_t keyid,
        return ret;
 }
 
+/*
+ * attempt to install the calling process's session keyring on the process's
+ * parent process
+ * - the keyring must exist and must grant us LINK permission
+ * - implements keyctl(KEYCTL_SESSION_TO_PARENT)
+ */
+long keyctl_session_to_parent(void)
+{
+       struct task_struct *me, *parent;
+       const struct cred *mycred, *pcred;
+       struct cred *cred, *oldcred;
+       key_ref_t keyring_r;
+       int ret;
+
+       keyring_r = lookup_user_key(KEY_SPEC_SESSION_KEYRING, 0, KEY_LINK);
+       if (IS_ERR(keyring_r))
+               return PTR_ERR(keyring_r);
+
+       /* our parent is going to need a new cred struct, a new tgcred struct
+        * and new security data, so we allocate them here to prevent ENOMEM in
+        * our parent */
+       ret = -ENOMEM;
+       cred = cred_alloc_blank();
+       if (!cred)
+               goto error_keyring;
+
+       cred->tgcred->session_keyring = key_ref_to_ptr(keyring_r);
+       keyring_r = NULL;
+
+       me = current;
+       write_lock_irq(&tasklist_lock);
+
+       parent = me->real_parent;
+       ret = -EPERM;
+
+       /* the parent mustn't be init and mustn't be a kernel thread */
+       if (parent->pid <= 1 || !parent->mm)
+               goto not_permitted;
+
+       /* the parent must be single threaded */
+       if (atomic_read(&parent->signal->count) != 1)
+               goto not_permitted;
+
+       /* the parent and the child must have different session keyrings or
+        * there's no point */
+       mycred = current_cred();
+       pcred = __task_cred(parent);
+       if (mycred == pcred ||
+           mycred->tgcred->session_keyring == pcred->tgcred->session_keyring)
+               goto already_same;
+
+       /* 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)
+               goto not_permitted;
+
+       /* the keyrings must have the same UID */
+       if (pcred ->tgcred->session_keyring->uid != mycred->euid ||
+           mycred->tgcred->session_keyring->uid != mycred->euid)
+               goto not_permitted;
+
+       /* the LSM must permit the replacement of the parent's keyring with the
+        * keyring from this process */
+       ret = security_key_session_to_parent(mycred, pcred,
+                                            key_ref_to_ptr(keyring_r));
+       if (ret < 0)
+               goto not_permitted;
+
+       /* if there's an already pending keyring replacement, then we replace
+        * that */
+       oldcred = parent->replacement_session_keyring;
+
+       /* the replacement session keyring is applied just prior to userspace
+        * restarting */
+       parent->replacement_session_keyring = cred;
+       cred = NULL;
+       set_ti_thread_flag(task_thread_info(parent), TIF_NOTIFY_RESUME);
+
+       write_unlock_irq(&tasklist_lock);
+       if (oldcred)
+               put_cred(oldcred);
+       return 0;
+
+already_same:
+       ret = 0;
+not_permitted:
+       write_unlock_irq(&tasklist_lock);
+       put_cred(cred);
+       return ret;
+
+error_keyring:
+       key_ref_put(keyring_r);
+       return ret;
+}
+
 /*****************************************************************************/
 /*
  * the key control system call
  */
-asmlinkage long sys_keyctl(int option, unsigned long arg2, unsigned long arg3,
-                          unsigned long arg4, unsigned long arg5)
+SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
+               unsigned long, arg4, unsigned long, arg5)
 {
        switch (option) {
        case KEYCTL_GET_KEYRING_ID:
@@ -1223,9 +1410,12 @@ asmlinkage long sys_keyctl(int option, unsigned long arg2, unsigned long arg3,
 
        case KEYCTL_GET_SECURITY:
                return keyctl_get_security((key_serial_t) arg2,
-                                          (char *) arg3,
+                                          (char __user *) arg3,
                                           (size_t) arg4);
 
+       case KEYCTL_SESSION_TO_PARENT:
+               return keyctl_session_to_parent();
+
        default:
                return -EOPNOTSUPP;
        }