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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /* Manage a process's keyrings
  *
  * Copyright (C) 2004-2005, 2008 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  */
 
 #include <linux/init.h>
 #include <linux/sched.h>
 #include <linux/sched/user.h>
 #include <linux/keyctl.h>
 #include <linux/fs.h>
 #include <linux/err.h>
 #include <linux/mutex.h>
 #include <linux/security.h>
 #include <linux/user_namespace.h>
 #include <linux/uaccess.h>
 #include <linux/init_task.h>
 #include <keys/request_key_auth-type.h>
 #include "internal.h"
 
 /* Session keyring create vs join semaphore */
 static DEFINE_MUTEX(key_session_mutex);
 
 /* The root user's tracking struct */
 struct key_user root_key_user = {
     .usage      = REFCOUNT_INIT(3),
     .cons_lock  = __MUTEX_INITIALIZER(root_key_user.cons_lock),
     .lock       = __SPIN_LOCK_UNLOCKED(root_key_user.lock),
     .nkeys      = ATOMIC_INIT(2),
     .nikeys     = ATOMIC_INIT(2),
     .uid        = GLOBAL_ROOT_UID,
 };
 
 /*
  * Get or create a user register keyring.
  */
 static struct key *get_user_register(struct user_namespace *user_ns)
 {
     struct key *reg_keyring = READ_ONCE(user_ns->user_keyring_register);
 
     if (reg_keyring)
         return reg_keyring;
 
     down_write(&user_ns->keyring_sem);
 
     /* Make sure there's a register keyring.  It gets owned by the
      * user_namespace's owner.
      */
     reg_keyring = user_ns->user_keyring_register;
     if (!reg_keyring) {
         reg_keyring = keyring_alloc(".user_reg",
                         user_ns->owner, INVALID_GID,
                         &init_cred,
                         KEY_POS_WRITE | KEY_POS_SEARCH |
                         KEY_USR_VIEW | KEY_USR_READ,
                         0,
                         NULL, NULL);
         if (!IS_ERR(reg_keyring))
             smp_store_release(&user_ns->user_keyring_register,
                       reg_keyring);
     }
 
     up_write(&user_ns->keyring_sem);
 
     /* We don't return a ref since the keyring is pinned by the user_ns */
     return reg_keyring;
 }
 
 /*
  * Look up the user and user session keyrings for the current process's UID,
  * creating them if they don't exist.
  */
 int look_up_user_keyrings(struct key **_user_keyring,
               struct key **_user_session_keyring)
 {
     const struct cred *cred = current_cred();
     struct user_namespace *user_ns = current_user_ns();
     struct key *reg_keyring, *uid_keyring, *session_keyring;
     key_perm_t user_keyring_perm;
     key_ref_t uid_keyring_r, session_keyring_r;
     uid_t uid = from_kuid(user_ns, cred->user->uid);
     char buf[20];
     int ret;
 
     user_keyring_perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL;
 
     kenter("%u", uid);
 
     reg_keyring = get_user_register(user_ns);
     if (IS_ERR(reg_keyring))
         return PTR_ERR(reg_keyring);
 
     down_write(&user_ns->keyring_sem);
     ret = 0;
 
     /* Get the user keyring.  Note that there may be one in existence
      * already as it may have been pinned by a session, but the user_struct
      * pointing to it may have been destroyed by setuid.
      */
     snprintf(buf, sizeof(buf), "_uid.%u", uid);
     uid_keyring_r = keyring_search(make_key_ref(reg_keyring, true),
                        &key_type_keyring, buf, false);
     kdebug("_uid %p", uid_keyring_r);
     if (uid_keyring_r == ERR_PTR(-EAGAIN)) {
         uid_keyring = keyring_alloc(buf, cred->user->uid, INVALID_GID,
                         cred, user_keyring_perm,
                         KEY_ALLOC_UID_KEYRING |
                         KEY_ALLOC_IN_QUOTA,
                         NULL, reg_keyring);
         if (IS_ERR(uid_keyring)) {
             ret = PTR_ERR(uid_keyring);
             goto error;
         }
     } else if (IS_ERR(uid_keyring_r)) {
         ret = PTR_ERR(uid_keyring_r);
         goto error;
     } else {
         uid_keyring = key_ref_to_ptr(uid_keyring_r);
     }
 
     /* Get a default session keyring (which might also exist already) */
     snprintf(buf, sizeof(buf), "_uid_ses.%u", uid);
     session_keyring_r = keyring_search(make_key_ref(reg_keyring, true),
                        &key_type_keyring, buf, false);
     kdebug("_uid_ses %p", session_keyring_r);
     if (session_keyring_r == ERR_PTR(-EAGAIN)) {
         session_keyring = keyring_alloc(buf, cred->user->uid, INVALID_GID,
                         cred, user_keyring_perm,
                         KEY_ALLOC_UID_KEYRING |
                         KEY_ALLOC_IN_QUOTA,
                         NULL, NULL);
         if (IS_ERR(session_keyring)) {
             ret = PTR_ERR(session_keyring);
             goto error_release;
         }
 
         /* We install a link from the user session keyring to
          * the user keyring.
          */
         ret = key_link(session_keyring, uid_keyring);
         if (ret < 0)
             goto error_release_session;
 
         /* And only then link the user-session keyring to the
          * register.
          */
         ret = key_link(reg_keyring, session_keyring);
         if (ret < 0)
             goto error_release_session;
     } else if (IS_ERR(session_keyring_r)) {
         ret = PTR_ERR(session_keyring_r);
         goto error_release;
     } else {
         session_keyring = key_ref_to_ptr(session_keyring_r);
     }
 
     up_write(&user_ns->keyring_sem);
 
     if (_user_session_keyring)
         *_user_session_keyring = session_keyring;
     else
         key_put(session_keyring);
     if (_user_keyring)
         *_user_keyring = uid_keyring;
     else
         key_put(uid_keyring);
     kleave(" = 0");
     return 0;
 
 error_release_session:
     key_put(session_keyring);
 error_release:
     key_put(uid_keyring);
 error:
     up_write(&user_ns->keyring_sem);
     kleave(" = %d", ret);
     return ret;
 }
 
 /*
  * Get the user session keyring if it exists, but don't create it if it
  * doesn't.
  */
 struct key *get_user_session_keyring_rcu(const struct cred *cred)
 {
     struct key *reg_keyring = READ_ONCE(cred->user_ns->user_keyring_register);
     key_ref_t session_keyring_r;
     char buf[20];
 
     struct keyring_search_context ctx = {
         .index_key.type     = &key_type_keyring,
         .index_key.description  = buf,
         .cred           = cred,
         .match_data.cmp     = key_default_cmp,
         .match_data.raw_data    = buf,
         .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
         .flags          = KEYRING_SEARCH_DO_STATE_CHECK,
     };
 
     if (!reg_keyring)
         return NULL;
 
     ctx.index_key.desc_len = snprintf(buf, sizeof(buf), "_uid_ses.%u",
                       from_kuid(cred->user_ns,
                             cred->user->uid));
 
     session_keyring_r = keyring_search_rcu(make_key_ref(reg_keyring, true),
                            &ctx);
     if (IS_ERR(session_keyring_r))
         return NULL;
     return key_ref_to_ptr(session_keyring_r);
 }
 
 /*
  * Install a thread keyring to the given credentials struct if it didn't have
  * one already.  This is allowed to overrun the quota.
  *
  * Return: 0 if a thread keyring is now present; -errno on failure.
  */
 int install_thread_keyring_to_cred(struct cred *new)
 {
     struct key *keyring;
 
     if (new->thread_keyring)
         return 0;
 
     keyring = keyring_alloc("_tid", new->uid, new->gid, new,
                 KEY_POS_ALL | KEY_USR_VIEW,
                 KEY_ALLOC_QUOTA_OVERRUN,
                 NULL, NULL);
     if (IS_ERR(keyring))
         return PTR_ERR(keyring);
 
     new->thread_keyring = keyring;
     return 0;
 }
 
 /*
  * Install a thread keyring to the current task if it didn't have one already.
  *
  * Return: 0 if a thread keyring is now present; -errno on failure.
  */
 static int install_thread_keyring(void)
 {
     struct cred *new;
     int ret;
 
     new = prepare_creds();
     if (!new)
         return -ENOMEM;
 
     ret = install_thread_keyring_to_cred(new);
     if (ret < 0) {
         abort_creds(new);
         return ret;
     }
 
     return commit_creds(new);
 }
 
 /*
  * Install a process keyring to the given credentials struct if it didn't have
  * one already.  This is allowed to overrun the quota.
  *
  * Return: 0 if a process keyring is now present; -errno on failure.
  */
 int install_process_keyring_to_cred(struct cred *new)
 {
     struct key *keyring;
 
     if (new->process_keyring)
         return 0;
 
     keyring = keyring_alloc("_pid", new->uid, new->gid, new,
                 KEY_POS_ALL | KEY_USR_VIEW,
                 KEY_ALLOC_QUOTA_OVERRUN,
                 NULL, NULL);
     if (IS_ERR(keyring))
         return PTR_ERR(keyring);
 
     new->process_keyring = keyring;
     return 0;
 }
 
 /*
  * Install a process keyring to the current task if it didn't have one already.
  *
  * Return: 0 if a process keyring is now present; -errno on failure.
  */
 static int install_process_keyring(void)
 {
     struct cred *new;
     int ret;
 
     new = prepare_creds();
     if (!new)
         return -ENOMEM;
 
     ret = install_process_keyring_to_cred(new);
     if (ret < 0) {
         abort_creds(new);
         return ret;
     }
 
     return commit_creds(new);
 }
 
 /*
  * Install the given keyring as the session keyring of the given credentials
  * struct, replacing the existing one if any.  If the given keyring is NULL,
  * then install a new anonymous session keyring.
  * @cred can not be in use by any task yet.
  *
  * Return: 0 on success; -errno on failure.
  */
 int install_session_keyring_to_cred(struct cred *cred, struct key *keyring)
 {
     unsigned long flags;
     struct key *old;
 
     might_sleep();
 
     /* create an empty session keyring */
     if (!keyring) {
         flags = KEY_ALLOC_QUOTA_OVERRUN;
         if (cred->session_keyring)
             flags = KEY_ALLOC_IN_QUOTA;
 
         keyring = keyring_alloc("_ses", cred->uid, cred->gid, cred,
                     KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ,
                     flags, NULL, NULL);
         if (IS_ERR(keyring))
             return PTR_ERR(keyring);
     } else {
         __key_get(keyring);
     }
 
     /* install the keyring */
     old = cred->session_keyring;
     cred->session_keyring = keyring;
 
     if (old)
         key_put(old);
 
     return 0;
 }
 
 /*
  * Install the given keyring as the session keyring of the current task,
  * replacing the existing one if any.  If the given keyring is NULL, then
  * install a new anonymous session keyring.
  *
  * Return: 0 on success; -errno on failure.
  */
 static int install_session_keyring(struct key *keyring)
 {
     struct cred *new;
     int ret;
 
     new = prepare_creds();
     if (!new)
         return -ENOMEM;
 
     ret = install_session_keyring_to_cred(new, keyring);
     if (ret < 0) {
         abort_creds(new);
         return ret;
     }
 
     return commit_creds(new);
 }
 
 /*
  * Handle the fsuid changing.
  */
 void key_fsuid_changed(struct cred *new_cred)
 {
     /* update the ownership of the thread keyring */
     if (new_cred->thread_keyring) {
         down_write(&new_cred->thread_keyring->sem);
         new_cred->thread_keyring->uid = new_cred->fsuid;
         up_write(&new_cred->thread_keyring->sem);
     }
 }
 
 /*
  * Handle the fsgid changing.
  */
 void key_fsgid_changed(struct cred *new_cred)
 {
     /* update the ownership of the thread keyring */
     if (new_cred->thread_keyring) {
         down_write(&new_cred->thread_keyring->sem);
         new_cred->thread_keyring->gid = new_cred->fsgid;
         up_write(&new_cred->thread_keyring->sem);
     }
 }
 
 /*
  * Search the process keyrings attached to the supplied cred for the first
  * matching key under RCU conditions (the caller must be holding the RCU read
  * lock).
  *
  * The search criteria are the type and the match function.  The description is
  * given to the match function as a parameter, but doesn't otherwise influence
  * the search.  Typically the match function will compare the description
  * parameter to the key's description.
  *
  * This can only search keyrings that grant Search permission to the supplied
  * credentials.  Keyrings linked to searched keyrings will also be searched if
  * they grant Search permission too.  Keys can only be found if they grant
  * Search permission to the credentials.
  *
  * Returns a pointer to the key with the key usage count incremented if
  * successful, -EAGAIN if we didn't find any matching key or -ENOKEY if we only
  * matched negative keys.
  *
  * In the case of a successful return, the possession attribute is set on the
  * returned key reference.
  */
 key_ref_t search_cred_keyrings_rcu(struct keyring_search_context *ctx)
 {
     struct key *user_session;
     key_ref_t key_ref, ret, err;
     const struct cred *cred = ctx->cred;
 
     /* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
      * searchable, but we failed to find a key or we found a negative key;
      * otherwise we want to return a sample error (probably -EACCES) if
      * none of the keyrings were searchable
      *
      * in terms of priority: success > -ENOKEY > -EAGAIN > other error
      */
     key_ref = NULL;
     ret = NULL;
     err = ERR_PTR(-EAGAIN);
 
     /* search the thread keyring first */
     if (cred->thread_keyring) {
         key_ref = keyring_search_rcu(
             make_key_ref(cred->thread_keyring, 1), ctx);
         if (!IS_ERR(key_ref))
             goto found;
 
         switch (PTR_ERR(key_ref)) {
         case -EAGAIN: /* no key */
         case -ENOKEY: /* negative key */
             ret = key_ref;
             break;
         default:
             err = key_ref;
             break;
         }
     }
 
     /* search the process keyring second */
     if (cred->process_keyring) {
         key_ref = keyring_search_rcu(
             make_key_ref(cred->process_keyring, 1), ctx);
         if (!IS_ERR(key_ref))
             goto found;
 
         switch (PTR_ERR(key_ref)) {
         case -EAGAIN: /* no key */
             if (ret)
                 break;
             fallthrough;
         case -ENOKEY: /* negative key */
             ret = key_ref;
             break;
         default:
             err = key_ref;
             break;
         }
     }
 
     /* search the session keyring */
     if (cred->session_keyring) {
         key_ref = keyring_search_rcu(
             make_key_ref(cred->session_keyring, 1), ctx);
 
         if (!IS_ERR(key_ref))
             goto found;
 
         switch (PTR_ERR(key_ref)) {
         case -EAGAIN: /* no key */
             if (ret)
                 break;
             fallthrough;
         case -ENOKEY: /* negative key */
             ret = key_ref;
             break;
         default:
             err = key_ref;
             break;
         }
     }
     /* or search the user-session keyring */
     else if ((user_session = get_user_session_keyring_rcu(cred))) {
         key_ref = keyring_search_rcu(make_key_ref(user_session, 1),
                          ctx);
         key_put(user_session);
 
         if (!IS_ERR(key_ref))
             goto found;
 
         switch (PTR_ERR(key_ref)) {
         case -EAGAIN: /* no key */
             if (ret)
                 break;
             fallthrough;
         case -ENOKEY: /* negative key */
             ret = key_ref;
             break;
         default:
             err = key_ref;
             break;
         }
     }
 
     /* no key - decide on the error we're going to go for */
     key_ref = ret ? ret : err;
 
 found:
     return key_ref;
 }
 
 /*
  * Search the process keyrings attached to the supplied cred for the first
  * matching key in the manner of search_my_process_keyrings(), but also search
  * the keys attached to the assumed authorisation key using its credentials if
  * one is available.
  *
  * The caller must be holding the RCU read lock.
  *
  * Return same as search_cred_keyrings_rcu().
  */
 key_ref_t search_process_keyrings_rcu(struct keyring_search_context *ctx)
 {
     struct request_key_auth *rka;
     key_ref_t key_ref, ret = ERR_PTR(-EACCES), err;
 
     key_ref = search_cred_keyrings_rcu(ctx);
     if (!IS_ERR(key_ref))
         goto found;
     err = key_ref;
 
     /* if this process has an instantiation authorisation key, then we also
      * search the keyrings of the process mentioned there
      * - we don't permit access to request_key auth keys via this method
      */
     if (ctx->cred->request_key_auth &&
         ctx->cred == current_cred() &&
         ctx->index_key.type != &key_type_request_key_auth
         ) {
         const struct cred *cred = ctx->cred;
 
         if (key_validate(cred->request_key_auth) == 0) {
             rka = ctx->cred->request_key_auth->payload.data[0];
 
             //// was search_process_keyrings() [ie. recursive]
             ctx->cred = rka->cred;
             key_ref = search_cred_keyrings_rcu(ctx);
             ctx->cred = cred;
 
             if (!IS_ERR(key_ref))
                 goto found;
             ret = key_ref;
         }
     }
 
     /* no key - decide on the error we're going to go for */
     if (err == ERR_PTR(-ENOKEY) || ret == ERR_PTR(-ENOKEY))
         key_ref = ERR_PTR(-ENOKEY);
     else if (err == ERR_PTR(-EACCES))
         key_ref = ret;
     else
         key_ref = err;
 
 found:
     return key_ref;
 }
 /*
  * See if the key we're looking at is the target key.
  */
 bool lookup_user_key_possessed(const struct key *key,
                    const struct key_match_data *match_data)
 {
     return key == match_data->raw_data;
 }
 
 /*
  * Look up a key ID given us by userspace with a given permissions mask to get
  * the key it refers to.
  *
  * Flags can be passed to request that special keyrings be created if referred
  * to directly, to permit partially constructed keys to be found and to skip
  * validity and permission checks on the found key.
  *
  * Returns a pointer to the key with an incremented usage count if successful;
  * -EINVAL if the key ID is invalid; -ENOKEY if the key ID does not correspond
  * to a key or the best found key was a negative key; -EKEYREVOKED or
  * -EKEYEXPIRED if the best found key was revoked or expired; -EACCES if the
  * found key doesn't grant the requested permit or the LSM denied access to it;
  * or -ENOMEM if a special keyring couldn't be created.
  *
  * In the case of a successful return, the possession attribute is set on the
  * returned key reference.
  */
 key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
               enum key_need_perm need_perm)
 {
     struct keyring_search_context ctx = {
         .match_data.cmp     = lookup_user_key_possessed,
         .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
         .flags          = (KEYRING_SEARCH_NO_STATE_CHECK |
                        KEYRING_SEARCH_RECURSE),
     };
     struct request_key_auth *rka;
     struct key *key, *user_session;
     key_ref_t key_ref, skey_ref;
     int ret;
 
 try_again:
     ctx.cred = get_current_cred();
     key_ref = ERR_PTR(-ENOKEY);
 
     switch (id) {
     case KEY_SPEC_THREAD_KEYRING:
         if (!ctx.cred->thread_keyring) {
             if (!(lflags & KEY_LOOKUP_CREATE))
                 goto error;
 
             ret = install_thread_keyring();
             if (ret < 0) {
                 key_ref = ERR_PTR(ret);
                 goto error;
             }
             goto reget_creds;
         }
 
         key = ctx.cred->thread_keyring;
         __key_get(key);
         key_ref = make_key_ref(key, 1);
         break;
 
     case KEY_SPEC_PROCESS_KEYRING:
         if (!ctx.cred->process_keyring) {
             if (!(lflags & KEY_LOOKUP_CREATE))
                 goto error;
 
             ret = install_process_keyring();
             if (ret < 0) {
                 key_ref = ERR_PTR(ret);
                 goto error;
             }
             goto reget_creds;
         }
 
         key = ctx.cred->process_keyring;
         __key_get(key);
         key_ref = make_key_ref(key, 1);
         break;
 
     case KEY_SPEC_SESSION_KEYRING:
         if (!ctx.cred->session_keyring) {
             /* always install a session keyring upon access if one
              * doesn't exist yet */
             ret = look_up_user_keyrings(NULL, &user_session);
             if (ret < 0)
                 goto error;
             if (lflags & KEY_LOOKUP_CREATE)
                 ret = join_session_keyring(NULL);
             else
                 ret = install_session_keyring(user_session);
 
             key_put(user_session);
             if (ret < 0)
                 goto error;
             goto reget_creds;
         } else if (test_bit(KEY_FLAG_UID_KEYRING,
                     &ctx.cred->session_keyring->flags) &&
                lflags & KEY_LOOKUP_CREATE) {
             ret = join_session_keyring(NULL);
             if (ret < 0)
                 goto error;
             goto reget_creds;
         }
 
         key = ctx.cred->session_keyring;
         __key_get(key);
         key_ref = make_key_ref(key, 1);
         break;
 
     case KEY_SPEC_USER_KEYRING:
         ret = look_up_user_keyrings(&key, NULL);
         if (ret < 0)
             goto error;
         key_ref = make_key_ref(key, 1);
         break;
 
     case KEY_SPEC_USER_SESSION_KEYRING:
         ret = look_up_user_keyrings(NULL, &key);
         if (ret < 0)
             goto error;
         key_ref = make_key_ref(key, 1);
         break;
 
     case KEY_SPEC_GROUP_KEYRING:
         /* group keyrings are not yet supported */
         key_ref = ERR_PTR(-EINVAL);
         goto error;
 
     case KEY_SPEC_REQKEY_AUTH_KEY:
         key = ctx.cred->request_key_auth;
         if (!key)
             goto error;
 
         __key_get(key);
         key_ref = make_key_ref(key, 1);
         break;
 
     case KEY_SPEC_REQUESTOR_KEYRING:
         if (!ctx.cred->request_key_auth)
             goto error;
 
         down_read(&ctx.cred->request_key_auth->sem);
         if (test_bit(KEY_FLAG_REVOKED,
                  &ctx.cred->request_key_auth->flags)) {
             key_ref = ERR_PTR(-EKEYREVOKED);
             key = NULL;
         } else {
             rka = ctx.cred->request_key_auth->payload.data[0];
             key = rka->dest_keyring;
             __key_get(key);
         }
         up_read(&ctx.cred->request_key_auth->sem);
         if (!key)
             goto error;
         key_ref = make_key_ref(key, 1);
         break;
 
     default:
         key_ref = ERR_PTR(-EINVAL);
         if (id < 1)
             goto error;
 
         key = key_lookup(id);
         if (IS_ERR(key)) {
             key_ref = ERR_CAST(key);
             goto error;
         }
 
         key_ref = make_key_ref(key, 0);
 
         /* check to see if we possess the key */
         ctx.index_key           = key->index_key;
         ctx.match_data.raw_data     = key;
         kdebug("check possessed");
         rcu_read_lock();
         skey_ref = search_process_keyrings_rcu(&ctx);
         rcu_read_unlock();
         kdebug("possessed=%p", skey_ref);
 
         if (!IS_ERR(skey_ref)) {
             key_put(key);
             key_ref = skey_ref;
         }
 
         break;
     }
 
     /* unlink does not use the nominated key in any way, so can skip all
      * the permission checks as it is only concerned with the keyring */
     if (need_perm != KEY_NEED_UNLINK) {
         if (!(lflags & KEY_LOOKUP_PARTIAL)) {
             ret = wait_for_key_construction(key, true);
             switch (ret) {
             case -ERESTARTSYS:
                 goto invalid_key;
             default:
                 if (need_perm != KEY_AUTHTOKEN_OVERRIDE &&
                     need_perm != KEY_DEFER_PERM_CHECK)
                     goto invalid_key;
                 break;
             case 0:
                 break;
             }
         } else if (need_perm != KEY_DEFER_PERM_CHECK) {
             ret = key_validate(key);
             if (ret < 0)
                 goto invalid_key;
         }
 
         ret = -EIO;
         if (!(lflags & KEY_LOOKUP_PARTIAL) &&
             key_read_state(key) == KEY_IS_UNINSTANTIATED)
             goto invalid_key;
     }
 
     /* check the permissions */
     ret = key_task_permission(key_ref, ctx.cred, need_perm);
     if (ret < 0)
         goto invalid_key;
 
     key->last_used_at = ktime_get_real_seconds();
 
 error:
     put_cred(ctx.cred);
     return key_ref;
 
 invalid_key:
     key_ref_put(key_ref);
     key_ref = ERR_PTR(ret);
     goto error;
 
     /* if we attempted to install a keyring, then it may have caused new
      * creds to be installed */
 reget_creds:
     put_cred(ctx.cred);
     goto try_again;
 }
 EXPORT_SYMBOL(lookup_user_key);
 
 /*
  * Join the named keyring as the session keyring if possible else attempt to
  * create a new one of that name and join that.
  *
  * If the name is NULL, an empty anonymous keyring will be installed as the
  * session keyring.
  *
  * Named session keyrings are joined with a semaphore held to prevent the
  * keyrings from going away whilst the attempt is made to going them and also
  * to prevent a race in creating compatible session keyrings.
  */
 long join_session_keyring(const char *name)
 {
     const struct cred *old;
     struct cred *new;
     struct key *keyring;
     long ret, serial;
 
     new = prepare_creds();
     if (!new)
         return -ENOMEM;
     old = current_cred();
 
     /* if no name is provided, install an anonymous keyring */
     if (!name) {
         ret = install_session_keyring_to_cred(new, NULL);
         if (ret < 0)
             goto error;
 
         serial = new->session_keyring->serial;
         ret = commit_creds(new);
         if (ret == 0)
             ret = serial;
         goto okay;
     }
 
     /* allow the user to join or create a named keyring */
     mutex_lock(&key_session_mutex);
 
     /* look for an existing keyring of this name */
     keyring = find_keyring_by_name(name, false);
     if (PTR_ERR(keyring) == -ENOKEY) {
         /* not found - try and create a new one */
         keyring = keyring_alloc(
             name, old->uid, old->gid, old,
             KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_LINK,
             KEY_ALLOC_IN_QUOTA, NULL, NULL);
         if (IS_ERR(keyring)) {
             ret = PTR_ERR(keyring);
             goto error2;
         }
     } else if (IS_ERR(keyring)) {
         ret = PTR_ERR(keyring);
         goto error2;
     } else if (keyring == new->session_keyring) {
         ret = 0;
         goto error3;
     }
 
     /* we've got a keyring - now to install it */
     ret = install_session_keyring_to_cred(new, keyring);
     if (ret < 0)
         goto error3;
 
     commit_creds(new);
     mutex_unlock(&key_session_mutex);
 
     ret = keyring->serial;
     key_put(keyring);
 okay:
     return ret;
 
 error3:
     key_put(keyring);
 error2:
     mutex_unlock(&key_session_mutex);
 error:
     abort_creds(new);
     return ret;
 }
 
 /*
  * Replace a process's session keyring on behalf of one of its children when
  * the target  process is about to resume userspace execution.
  */
 void key_change_session_keyring(struct callback_head *twork)
 {
     const struct cred *old = current_cred();
     struct cred *new = container_of(twork, struct cred, rcu);
 
     if (unlikely(current->flags & PF_EXITING)) {
         put_cred(new);
         return;
     }
 
     /* If get_ucounts fails more bits are needed in the refcount */
     if (unlikely(!get_ucounts(old->ucounts))) {
         WARN_ONCE(1, "In %s get_ucounts failed\n", __func__);
         put_cred(new);
         return;
     }
 
     new->  uid  = old->  uid;
     new-> euid  = old-> euid;
     new-> suid  = old-> suid;
     new->fsuid  = old->fsuid;
     new->  gid  = old->  gid;
     new-> egid  = old-> egid;
     new-> sgid  = old-> sgid;
     new->fsgid  = old->fsgid;
     new->user   = get_uid(old->user);
     new->ucounts    = old->ucounts;
     new->user_ns    = get_user_ns(old->user_ns);
     new->group_info = get_group_info(old->group_info);
 
     new->securebits = old->securebits;
     new->cap_inheritable    = old->cap_inheritable;
     new->cap_permitted  = old->cap_permitted;
     new->cap_effective  = old->cap_effective;
     new->cap_ambient    = old->cap_ambient;
     new->cap_bset       = old->cap_bset;
 
     new->jit_keyring    = old->jit_keyring;
     new->thread_keyring = key_get(old->thread_keyring);
     new->process_keyring    = key_get(old->process_keyring);
 
     security_transfer_creds(new, old);
 
     commit_creds(new);
 }
 
 /*
  * Make sure that root's user and user-session keyrings exist.
  */
 static int __init init_root_keyring(void)
 {
     return look_up_user_keyrings(NULL, NULL);
 }
 
 late_initcall(init_root_keyring);

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