diff options
Diffstat (limited to 'security/keys/process_keys.c')
| -rw-r--r-- | security/keys/process_keys.c | 965 |
1 files changed, 965 insertions, 0 deletions
diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c new file mode 100644 index 000000000..b5d5333ab --- /dev/null +++ b/security/keys/process_keys.c @@ -0,0 +1,965 @@ +// 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); |