| /* Keyring handling |
| * |
| * Copyright (C) 2004-2005, 2008 Red Hat, Inc. All Rights Reserved. |
| * Written by David Howells (dhowells@redhat.com) |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License |
| * as published by the Free Software Foundation; either version |
| * 2 of the License, or (at your option) any later version. |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/init.h> |
| #include <linux/sched.h> |
| #include <linux/slab.h> |
| #include <linux/security.h> |
| #include <linux/seq_file.h> |
| #include <linux/err.h> |
| #include <keys/keyring-type.h> |
| #include <asm/uaccess.h> |
| #include "internal.h" |
| |
| /* |
| * when plumbing the depths of the key tree, this sets a hard limit set on how |
| * deep we're willing to go |
| */ |
| #define KEYRING_SEARCH_MAX_DEPTH 6 |
| |
| /* |
| * we keep all named keyrings in a hash to speed looking them up |
| */ |
| #define KEYRING_NAME_HASH_SIZE (1 << 5) |
| |
| static struct list_head keyring_name_hash[KEYRING_NAME_HASH_SIZE]; |
| static DEFINE_RWLOCK(keyring_name_lock); |
| |
| static inline unsigned keyring_hash(const char *desc) |
| { |
| unsigned bucket = 0; |
| |
| for (; *desc; desc++) |
| bucket += (unsigned char) *desc; |
| |
| return bucket & (KEYRING_NAME_HASH_SIZE - 1); |
| } |
| |
| /* |
| * the keyring type definition |
| */ |
| static int keyring_instantiate(struct key *keyring, |
| const void *data, size_t datalen); |
| static int keyring_match(const struct key *keyring, const void *criterion); |
| static void keyring_revoke(struct key *keyring); |
| static void keyring_destroy(struct key *keyring); |
| static void keyring_describe(const struct key *keyring, struct seq_file *m); |
| static long keyring_read(const struct key *keyring, |
| char __user *buffer, size_t buflen); |
| |
| struct key_type key_type_keyring = { |
| .name = "keyring", |
| .def_datalen = sizeof(struct keyring_list), |
| .instantiate = keyring_instantiate, |
| .match = keyring_match, |
| .revoke = keyring_revoke, |
| .destroy = keyring_destroy, |
| .describe = keyring_describe, |
| .read = keyring_read, |
| }; |
| |
| EXPORT_SYMBOL(key_type_keyring); |
| |
| /* |
| * semaphore to serialise link/link calls to prevent two link calls in parallel |
| * introducing a cycle |
| */ |
| static DECLARE_RWSEM(keyring_serialise_link_sem); |
| |
| /*****************************************************************************/ |
| /* |
| * publish the name of a keyring so that it can be found by name (if it has |
| * one) |
| */ |
| static void keyring_publish_name(struct key *keyring) |
| { |
| int bucket; |
| |
| if (keyring->description) { |
| bucket = keyring_hash(keyring->description); |
| |
| write_lock(&keyring_name_lock); |
| |
| if (!keyring_name_hash[bucket].next) |
| INIT_LIST_HEAD(&keyring_name_hash[bucket]); |
| |
| list_add_tail(&keyring->type_data.link, |
| &keyring_name_hash[bucket]); |
| |
| write_unlock(&keyring_name_lock); |
| } |
| |
| } /* end keyring_publish_name() */ |
| |
| /*****************************************************************************/ |
| /* |
| * initialise a keyring |
| * - we object if we were given any data |
| */ |
| static int keyring_instantiate(struct key *keyring, |
| const void *data, size_t datalen) |
| { |
| int ret; |
| |
| ret = -EINVAL; |
| if (datalen == 0) { |
| /* make the keyring available by name if it has one */ |
| keyring_publish_name(keyring); |
| ret = 0; |
| } |
| |
| return ret; |
| |
| } /* end keyring_instantiate() */ |
| |
| /*****************************************************************************/ |
| /* |
| * match keyrings on their name |
| */ |
| static int keyring_match(const struct key *keyring, const void *description) |
| { |
| return keyring->description && |
| strcmp(keyring->description, description) == 0; |
| |
| } /* end keyring_match() */ |
| |
| /*****************************************************************************/ |
| /* |
| * dispose of the data dangling from the corpse of a keyring |
| */ |
| static void keyring_destroy(struct key *keyring) |
| { |
| struct keyring_list *klist; |
| int loop; |
| |
| if (keyring->description) { |
| write_lock(&keyring_name_lock); |
| |
| if (keyring->type_data.link.next != NULL && |
| !list_empty(&keyring->type_data.link)) |
| list_del(&keyring->type_data.link); |
| |
| write_unlock(&keyring_name_lock); |
| } |
| |
| klist = rcu_dereference(keyring->payload.subscriptions); |
| if (klist) { |
| for (loop = klist->nkeys - 1; loop >= 0; loop--) |
| key_put(klist->keys[loop]); |
| kfree(klist); |
| } |
| |
| } /* end keyring_destroy() */ |
| |
| /*****************************************************************************/ |
| /* |
| * describe the keyring |
| */ |
| static void keyring_describe(const struct key *keyring, struct seq_file *m) |
| { |
| struct keyring_list *klist; |
| |
| if (keyring->description) { |
| seq_puts(m, keyring->description); |
| } |
| else { |
| seq_puts(m, "[anon]"); |
| } |
| |
| rcu_read_lock(); |
| klist = rcu_dereference(keyring->payload.subscriptions); |
| if (klist) |
| seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys); |
| else |
| seq_puts(m, ": empty"); |
| rcu_read_unlock(); |
| |
| } /* end keyring_describe() */ |
| |
| /*****************************************************************************/ |
| /* |
| * read a list of key IDs from the keyring's contents |
| * - the keyring's semaphore is read-locked |
| */ |
| static long keyring_read(const struct key *keyring, |
| char __user *buffer, size_t buflen) |
| { |
| struct keyring_list *klist; |
| struct key *key; |
| size_t qty, tmp; |
| int loop, ret; |
| |
| ret = 0; |
| klist = rcu_dereference(keyring->payload.subscriptions); |
| |
| if (klist) { |
| /* calculate how much data we could return */ |
| qty = klist->nkeys * sizeof(key_serial_t); |
| |
| if (buffer && buflen > 0) { |
| if (buflen > qty) |
| buflen = qty; |
| |
| /* copy the IDs of the subscribed keys into the |
| * buffer */ |
| ret = -EFAULT; |
| |
| for (loop = 0; loop < klist->nkeys; loop++) { |
| key = klist->keys[loop]; |
| |
| tmp = sizeof(key_serial_t); |
| if (tmp > buflen) |
| tmp = buflen; |
| |
| if (copy_to_user(buffer, |
| &key->serial, |
| tmp) != 0) |
| goto error; |
| |
| buflen -= tmp; |
| if (buflen == 0) |
| break; |
| buffer += tmp; |
| } |
| } |
| |
| ret = qty; |
| } |
| |
| error: |
| return ret; |
| |
| } /* end keyring_read() */ |
| |
| /*****************************************************************************/ |
| /* |
| * allocate a keyring and link into the destination keyring |
| */ |
| struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid, |
| const struct cred *cred, unsigned long flags, |
| struct key *dest) |
| { |
| struct key *keyring; |
| int ret; |
| |
| keyring = key_alloc(&key_type_keyring, description, |
| uid, gid, cred, |
| (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL, |
| flags); |
| |
| if (!IS_ERR(keyring)) { |
| ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL); |
| if (ret < 0) { |
| key_put(keyring); |
| keyring = ERR_PTR(ret); |
| } |
| } |
| |
| return keyring; |
| |
| } /* end keyring_alloc() */ |
| |
| /*****************************************************************************/ |
| /* |
| * search the supplied keyring tree for a key that matches the criterion |
| * - perform a breadth-then-depth search up to the prescribed limit |
| * - we only find keys on which we have search permission |
| * - we use the supplied match function to see if the description (or other |
| * feature of interest) matches |
| * - we rely on RCU to prevent the keyring lists from disappearing on us |
| * - we return -EAGAIN if we didn't find any matching key |
| * - we return -ENOKEY if we only found negative matching keys |
| * - we propagate the possession attribute from the keyring ref to the key ref |
| */ |
| key_ref_t keyring_search_aux(key_ref_t keyring_ref, |
| const struct cred *cred, |
| struct key_type *type, |
| const void *description, |
| key_match_func_t match) |
| { |
| struct { |
| struct keyring_list *keylist; |
| int kix; |
| } stack[KEYRING_SEARCH_MAX_DEPTH]; |
| |
| struct keyring_list *keylist; |
| struct timespec now; |
| unsigned long possessed, kflags; |
| struct key *keyring, *key; |
| key_ref_t key_ref; |
| long err; |
| int sp, kix; |
| |
| keyring = key_ref_to_ptr(keyring_ref); |
| possessed = is_key_possessed(keyring_ref); |
| key_check(keyring); |
| |
| /* top keyring must have search permission to begin the search */ |
| err = key_task_permission(keyring_ref, cred, KEY_SEARCH); |
| if (err < 0) { |
| key_ref = ERR_PTR(err); |
| goto error; |
| } |
| |
| key_ref = ERR_PTR(-ENOTDIR); |
| if (keyring->type != &key_type_keyring) |
| goto error; |
| |
| rcu_read_lock(); |
| |
| now = current_kernel_time(); |
| err = -EAGAIN; |
| sp = 0; |
| |
| /* firstly we should check to see if this top-level keyring is what we |
| * are looking for */ |
| key_ref = ERR_PTR(-EAGAIN); |
| kflags = keyring->flags; |
| if (keyring->type == type && match(keyring, description)) { |
| key = keyring; |
| |
| /* check it isn't negative and hasn't expired or been |
| * revoked */ |
| if (kflags & (1 << KEY_FLAG_REVOKED)) |
| goto error_2; |
| if (key->expiry && now.tv_sec >= key->expiry) |
| goto error_2; |
| key_ref = ERR_PTR(-ENOKEY); |
| if (kflags & (1 << KEY_FLAG_NEGATIVE)) |
| goto error_2; |
| goto found; |
| } |
| |
| /* otherwise, the top keyring must not be revoked, expired, or |
| * negatively instantiated if we are to search it */ |
| key_ref = ERR_PTR(-EAGAIN); |
| if (kflags & ((1 << KEY_FLAG_REVOKED) | (1 << KEY_FLAG_NEGATIVE)) || |
| (keyring->expiry && now.tv_sec >= keyring->expiry)) |
| goto error_2; |
| |
| /* start processing a new keyring */ |
| descend: |
| if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
| goto not_this_keyring; |
| |
| keylist = rcu_dereference(keyring->payload.subscriptions); |
| if (!keylist) |
| goto not_this_keyring; |
| |
| /* iterate through the keys in this keyring first */ |
| for (kix = 0; kix < keylist->nkeys; kix++) { |
| key = keylist->keys[kix]; |
| kflags = key->flags; |
| |
| /* ignore keys not of this type */ |
| if (key->type != type) |
| continue; |
| |
| /* skip revoked keys and expired keys */ |
| if (kflags & (1 << KEY_FLAG_REVOKED)) |
| continue; |
| |
| if (key->expiry && now.tv_sec >= key->expiry) |
| continue; |
| |
| /* keys that don't match */ |
| if (!match(key, description)) |
| continue; |
| |
| /* key must have search permissions */ |
| if (key_task_permission(make_key_ref(key, possessed), |
| cred, KEY_SEARCH) < 0) |
| continue; |
| |
| /* we set a different error code if we pass a negative key */ |
| if (kflags & (1 << KEY_FLAG_NEGATIVE)) { |
| err = -ENOKEY; |
| continue; |
| } |
| |
| goto found; |
| } |
| |
| /* search through the keyrings nested in this one */ |
| kix = 0; |
| ascend: |
| for (; kix < keylist->nkeys; kix++) { |
| key = keylist->keys[kix]; |
| if (key->type != &key_type_keyring) |
| continue; |
| |
| /* recursively search nested keyrings |
| * - only search keyrings for which we have search permission |
| */ |
| if (sp >= KEYRING_SEARCH_MAX_DEPTH) |
| continue; |
| |
| if (key_task_permission(make_key_ref(key, possessed), |
| cred, KEY_SEARCH) < 0) |
| continue; |
| |
| /* stack the current position */ |
| stack[sp].keylist = keylist; |
| stack[sp].kix = kix; |
| sp++; |
| |
| /* begin again with the new keyring */ |
| keyring = key; |
| goto descend; |
| } |
| |
| /* the keyring we're looking at was disqualified or didn't contain a |
| * matching key */ |
| not_this_keyring: |
| if (sp > 0) { |
| /* resume the processing of a keyring higher up in the tree */ |
| sp--; |
| keylist = stack[sp].keylist; |
| kix = stack[sp].kix + 1; |
| goto ascend; |
| } |
| |
| key_ref = ERR_PTR(err); |
| goto error_2; |
| |
| /* we found a viable match */ |
| found: |
| atomic_inc(&key->usage); |
| key_check(key); |
| key_ref = make_key_ref(key, possessed); |
| error_2: |
| rcu_read_unlock(); |
| error: |
| return key_ref; |
| |
| } /* end keyring_search_aux() */ |
| |
| /*****************************************************************************/ |
| /* |
| * search the supplied keyring tree for a key that matches the criterion |
| * - perform a breadth-then-depth search up to the prescribed limit |
| * - we only find keys on which we have search permission |
| * - we readlock the keyrings as we search down the tree |
| * - we return -EAGAIN if we didn't find any matching key |
| * - we return -ENOKEY if we only found negative matching keys |
| */ |
| key_ref_t keyring_search(key_ref_t keyring, |
| struct key_type *type, |
| const char *description) |
| { |
| if (!type->match) |
| return ERR_PTR(-ENOKEY); |
| |
| return keyring_search_aux(keyring, current->cred, |
| type, description, type->match); |
| |
| } /* end keyring_search() */ |
| |
| EXPORT_SYMBOL(keyring_search); |
| |
| /*****************************************************************************/ |
| /* |
| * search the given keyring only (no recursion) |
| * - keyring must be locked by caller |
| * - caller must guarantee that the keyring is a keyring |
| */ |
| key_ref_t __keyring_search_one(key_ref_t keyring_ref, |
| const struct key_type *ktype, |
| const char *description, |
| key_perm_t perm) |
| { |
| struct keyring_list *klist; |
| unsigned long possessed; |
| struct key *keyring, *key; |
| int loop; |
| |
| keyring = key_ref_to_ptr(keyring_ref); |
| possessed = is_key_possessed(keyring_ref); |
| |
| rcu_read_lock(); |
| |
| klist = rcu_dereference(keyring->payload.subscriptions); |
| if (klist) { |
| for (loop = 0; loop < klist->nkeys; loop++) { |
| key = klist->keys[loop]; |
| |
| if (key->type == ktype && |
| (!key->type->match || |
| key->type->match(key, description)) && |
| key_permission(make_key_ref(key, possessed), |
| perm) == 0 && |
| !test_bit(KEY_FLAG_REVOKED, &key->flags) |
| ) |
| goto found; |
| } |
| } |
| |
| rcu_read_unlock(); |
| return ERR_PTR(-ENOKEY); |
| |
| found: |
| atomic_inc(&key->usage); |
| rcu_read_unlock(); |
| return make_key_ref(key, possessed); |
| |
| } /* end __keyring_search_one() */ |
| |
| /*****************************************************************************/ |
| /* |
| * find a keyring with the specified name |
| * - all named keyrings are searched |
| * - normally only finds keyrings with search permission for the current process |
| */ |
| struct key *find_keyring_by_name(const char *name, bool skip_perm_check) |
| { |
| struct key *keyring; |
| int bucket; |
| |
| if (!name) |
| return ERR_PTR(-EINVAL); |
| |
| bucket = keyring_hash(name); |
| |
| read_lock(&keyring_name_lock); |
| |
| if (keyring_name_hash[bucket].next) { |
| /* search this hash bucket for a keyring with a matching name |
| * that's readable and that hasn't been revoked */ |
| list_for_each_entry(keyring, |
| &keyring_name_hash[bucket], |
| type_data.link |
| ) { |
| if (keyring->user->user_ns != current_user_ns()) |
| continue; |
| |
| if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
| continue; |
| |
| if (strcmp(keyring->description, name) != 0) |
| continue; |
| |
| if (!skip_perm_check && |
| key_permission(make_key_ref(keyring, 0), |
| KEY_SEARCH) < 0) |
| continue; |
| |
| /* we've got a match but we might end up racing with |
| * key_cleanup() if the keyring is currently 'dead' |
| * (ie. it has a zero usage count) */ |
| if (!atomic_inc_not_zero(&keyring->usage)) |
| continue; |
| goto out; |
| } |
| } |
| |
| keyring = ERR_PTR(-ENOKEY); |
| out: |
| read_unlock(&keyring_name_lock); |
| return keyring; |
| |
| } /* end find_keyring_by_name() */ |
| |
| /*****************************************************************************/ |
| /* |
| * see if a cycle will will be created by inserting acyclic tree B in acyclic |
| * tree A at the topmost level (ie: as a direct child of A) |
| * - since we are adding B to A at the top level, checking for cycles should |
| * just be a matter of seeing if node A is somewhere in tree B |
| */ |
| static int keyring_detect_cycle(struct key *A, struct key *B) |
| { |
| struct { |
| struct keyring_list *keylist; |
| int kix; |
| } stack[KEYRING_SEARCH_MAX_DEPTH]; |
| |
| struct keyring_list *keylist; |
| struct key *subtree, *key; |
| int sp, kix, ret; |
| |
| rcu_read_lock(); |
| |
| ret = -EDEADLK; |
| if (A == B) |
| goto cycle_detected; |
| |
| subtree = B; |
| sp = 0; |
| |
| /* start processing a new keyring */ |
| descend: |
| if (test_bit(KEY_FLAG_REVOKED, &subtree->flags)) |
| goto not_this_keyring; |
| |
| keylist = rcu_dereference(subtree->payload.subscriptions); |
| if (!keylist) |
| goto not_this_keyring; |
| kix = 0; |
| |
| ascend: |
| /* iterate through the remaining keys in this keyring */ |
| for (; kix < keylist->nkeys; kix++) { |
| key = keylist->keys[kix]; |
| |
| if (key == A) |
| goto cycle_detected; |
| |
| /* recursively check nested keyrings */ |
| if (key->type == &key_type_keyring) { |
| if (sp >= KEYRING_SEARCH_MAX_DEPTH) |
| goto too_deep; |
| |
| /* stack the current position */ |
| stack[sp].keylist = keylist; |
| stack[sp].kix = kix; |
| sp++; |
| |
| /* begin again with the new keyring */ |
| subtree = key; |
| goto descend; |
| } |
| } |
| |
| /* the keyring we're looking at was disqualified or didn't contain a |
| * matching key */ |
| not_this_keyring: |
| if (sp > 0) { |
| /* resume the checking of a keyring higher up in the tree */ |
| sp--; |
| keylist = stack[sp].keylist; |
| kix = stack[sp].kix + 1; |
| goto ascend; |
| } |
| |
| ret = 0; /* no cycles detected */ |
| |
| error: |
| rcu_read_unlock(); |
| return ret; |
| |
| too_deep: |
| ret = -ELOOP; |
| goto error; |
| |
| cycle_detected: |
| ret = -EDEADLK; |
| goto error; |
| |
| } /* end keyring_detect_cycle() */ |
| |
| /*****************************************************************************/ |
| /* |
| * dispose of a keyring list after the RCU grace period |
| */ |
| static void keyring_link_rcu_disposal(struct rcu_head *rcu) |
| { |
| struct keyring_list *klist = |
| container_of(rcu, struct keyring_list, rcu); |
| |
| kfree(klist); |
| |
| } /* end keyring_link_rcu_disposal() */ |
| |
| /*****************************************************************************/ |
| /* |
| * dispose of a keyring list after the RCU grace period, freeing the unlinked |
| * key |
| */ |
| static void keyring_unlink_rcu_disposal(struct rcu_head *rcu) |
| { |
| struct keyring_list *klist = |
| container_of(rcu, struct keyring_list, rcu); |
| |
| key_put(klist->keys[klist->delkey]); |
| kfree(klist); |
| |
| } /* end keyring_unlink_rcu_disposal() */ |
| |
| /*****************************************************************************/ |
| /* |
| * link a key into to a keyring |
| * - must be called with the keyring's semaphore write-locked |
| * - discard already extant link to matching key if there is one |
| */ |
| int __key_link(struct key *keyring, struct key *key) |
| { |
| struct keyring_list *klist, *nklist; |
| unsigned max; |
| size_t size; |
| int loop, ret; |
| |
| ret = -EKEYREVOKED; |
| if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
| goto error; |
| |
| ret = -ENOTDIR; |
| if (keyring->type != &key_type_keyring) |
| goto error; |
| |
| /* serialise link/link calls to prevent parallel calls causing a |
| * cycle when applied to two keyring in opposite orders */ |
| down_write(&keyring_serialise_link_sem); |
| |
| /* check that we aren't going to create a cycle adding one keyring to |
| * another */ |
| if (key->type == &key_type_keyring) { |
| ret = keyring_detect_cycle(keyring, key); |
| if (ret < 0) |
| goto error2; |
| } |
| |
| /* see if there's a matching key we can displace */ |
| klist = keyring->payload.subscriptions; |
| |
| if (klist && klist->nkeys > 0) { |
| struct key_type *type = key->type; |
| |
| for (loop = klist->nkeys - 1; loop >= 0; loop--) { |
| if (klist->keys[loop]->type == type && |
| strcmp(klist->keys[loop]->description, |
| key->description) == 0 |
| ) { |
| /* found a match - replace with new key */ |
| size = sizeof(struct key *) * klist->maxkeys; |
| size += sizeof(*klist); |
| BUG_ON(size > PAGE_SIZE); |
| |
| ret = -ENOMEM; |
| nklist = kmemdup(klist, size, GFP_KERNEL); |
| if (!nklist) |
| goto error2; |
| |
| /* replace matched key */ |
| atomic_inc(&key->usage); |
| nklist->keys[loop] = key; |
| |
| rcu_assign_pointer( |
| keyring->payload.subscriptions, |
| nklist); |
| |
| /* dispose of the old keyring list and the |
| * displaced key */ |
| klist->delkey = loop; |
| call_rcu(&klist->rcu, |
| keyring_unlink_rcu_disposal); |
| |
| goto done; |
| } |
| } |
| } |
| |
| /* check that we aren't going to overrun the user's quota */ |
| ret = key_payload_reserve(keyring, |
| keyring->datalen + KEYQUOTA_LINK_BYTES); |
| if (ret < 0) |
| goto error2; |
| |
| klist = keyring->payload.subscriptions; |
| |
| if (klist && klist->nkeys < klist->maxkeys) { |
| /* there's sufficient slack space to add directly */ |
| atomic_inc(&key->usage); |
| |
| klist->keys[klist->nkeys] = key; |
| smp_wmb(); |
| klist->nkeys++; |
| smp_wmb(); |
| } |
| else { |
| /* grow the key list */ |
| max = 4; |
| if (klist) |
| max += klist->maxkeys; |
| |
| ret = -ENFILE; |
| if (max > 65535) |
| goto error3; |
| size = sizeof(*klist) + sizeof(struct key *) * max; |
| if (size > PAGE_SIZE) |
| goto error3; |
| |
| ret = -ENOMEM; |
| nklist = kmalloc(size, GFP_KERNEL); |
| if (!nklist) |
| goto error3; |
| nklist->maxkeys = max; |
| nklist->nkeys = 0; |
| |
| if (klist) { |
| nklist->nkeys = klist->nkeys; |
| memcpy(nklist->keys, |
| klist->keys, |
| sizeof(struct key *) * klist->nkeys); |
| } |
| |
| /* add the key into the new space */ |
| atomic_inc(&key->usage); |
| nklist->keys[nklist->nkeys++] = key; |
| |
| rcu_assign_pointer(keyring->payload.subscriptions, nklist); |
| |
| /* dispose of the old keyring list */ |
| if (klist) |
| call_rcu(&klist->rcu, keyring_link_rcu_disposal); |
| } |
| |
| done: |
| ret = 0; |
| error2: |
| up_write(&keyring_serialise_link_sem); |
| error: |
| return ret; |
| |
| error3: |
| /* undo the quota changes */ |
| key_payload_reserve(keyring, |
| keyring->datalen - KEYQUOTA_LINK_BYTES); |
| goto error2; |
| |
| } /* end __key_link() */ |
| |
| /*****************************************************************************/ |
| /* |
| * link a key to a keyring |
| */ |
| int key_link(struct key *keyring, struct key *key) |
| { |
| int ret; |
| |
| key_check(keyring); |
| key_check(key); |
| |
| down_write(&keyring->sem); |
| ret = __key_link(keyring, key); |
| up_write(&keyring->sem); |
| |
| return ret; |
| |
| } /* end key_link() */ |
| |
| EXPORT_SYMBOL(key_link); |
| |
| /*****************************************************************************/ |
| /* |
| * unlink the first link to a key from a keyring |
| */ |
| int key_unlink(struct key *keyring, struct key *key) |
| { |
| struct keyring_list *klist, *nklist; |
| int loop, ret; |
| |
| key_check(keyring); |
| key_check(key); |
| |
| ret = -ENOTDIR; |
| if (keyring->type != &key_type_keyring) |
| goto error; |
| |
| down_write(&keyring->sem); |
| |
| klist = keyring->payload.subscriptions; |
| if (klist) { |
| /* search the keyring for the key */ |
| for (loop = 0; loop < klist->nkeys; loop++) |
| if (klist->keys[loop] == key) |
| goto key_is_present; |
| } |
| |
| up_write(&keyring->sem); |
| ret = -ENOENT; |
| goto error; |
| |
| key_is_present: |
| /* we need to copy the key list for RCU purposes */ |
| nklist = kmalloc(sizeof(*klist) + |
| sizeof(struct key *) * klist->maxkeys, |
| GFP_KERNEL); |
| if (!nklist) |
| goto nomem; |
| nklist->maxkeys = klist->maxkeys; |
| nklist->nkeys = klist->nkeys - 1; |
| |
| if (loop > 0) |
| memcpy(&nklist->keys[0], |
| &klist->keys[0], |
| loop * sizeof(struct key *)); |
| |
| if (loop < nklist->nkeys) |
| memcpy(&nklist->keys[loop], |
| &klist->keys[loop + 1], |
| (nklist->nkeys - loop) * sizeof(struct key *)); |
| |
| /* adjust the user's quota */ |
| key_payload_reserve(keyring, |
| keyring->datalen - KEYQUOTA_LINK_BYTES); |
| |
| rcu_assign_pointer(keyring->payload.subscriptions, nklist); |
| |
| up_write(&keyring->sem); |
| |
| /* schedule for later cleanup */ |
| klist->delkey = loop; |
| call_rcu(&klist->rcu, keyring_unlink_rcu_disposal); |
| |
| ret = 0; |
| |
| error: |
| return ret; |
| nomem: |
| ret = -ENOMEM; |
| up_write(&keyring->sem); |
| goto error; |
| |
| } /* end key_unlink() */ |
| |
| EXPORT_SYMBOL(key_unlink); |
| |
| /*****************************************************************************/ |
| /* |
| * dispose of a keyring list after the RCU grace period, releasing the keys it |
| * links to |
| */ |
| static void keyring_clear_rcu_disposal(struct rcu_head *rcu) |
| { |
| struct keyring_list *klist; |
| int loop; |
| |
| klist = container_of(rcu, struct keyring_list, rcu); |
| |
| for (loop = klist->nkeys - 1; loop >= 0; loop--) |
| key_put(klist->keys[loop]); |
| |
| kfree(klist); |
| |
| } /* end keyring_clear_rcu_disposal() */ |
| |
| /*****************************************************************************/ |
| /* |
| * clear the specified process keyring |
| * - implements keyctl(KEYCTL_CLEAR) |
| */ |
| int keyring_clear(struct key *keyring) |
| { |
| struct keyring_list *klist; |
| int ret; |
| |
| ret = -ENOTDIR; |
| if (keyring->type == &key_type_keyring) { |
| /* detach the pointer block with the locks held */ |
| down_write(&keyring->sem); |
| |
| klist = keyring->payload.subscriptions; |
| if (klist) { |
| /* adjust the quota */ |
| key_payload_reserve(keyring, |
| sizeof(struct keyring_list)); |
| |
| rcu_assign_pointer(keyring->payload.subscriptions, |
| NULL); |
| } |
| |
| up_write(&keyring->sem); |
| |
| /* free the keys after the locks have been dropped */ |
| if (klist) |
| call_rcu(&klist->rcu, keyring_clear_rcu_disposal); |
| |
| ret = 0; |
| } |
| |
| return ret; |
| |
| } /* end keyring_clear() */ |
| |
| EXPORT_SYMBOL(keyring_clear); |
| |
| /*****************************************************************************/ |
| /* |
| * dispose of the links from a revoked keyring |
| * - called with the key sem write-locked |
| */ |
| static void keyring_revoke(struct key *keyring) |
| { |
| struct keyring_list *klist = keyring->payload.subscriptions; |
| |
| /* adjust the quota */ |
| key_payload_reserve(keyring, 0); |
| |
| if (klist) { |
| rcu_assign_pointer(keyring->payload.subscriptions, NULL); |
| call_rcu(&klist->rcu, keyring_clear_rcu_disposal); |
| } |
| |
| } /* end keyring_revoke() */ |
| |
| /* |
| * Determine whether a key is dead |
| */ |
| static bool key_is_dead(struct key *key, time_t limit) |
| { |
| return test_bit(KEY_FLAG_DEAD, &key->flags) || |
| (key->expiry > 0 && key->expiry <= limit); |
| } |
| |
| /* |
| * Collect garbage from the contents of a keyring |
| */ |
| void keyring_gc(struct key *keyring, time_t limit) |
| { |
| struct keyring_list *klist, *new; |
| struct key *key; |
| int loop, keep, max; |
| |
| kenter("{%x,%s}", key_serial(keyring), keyring->description); |
| |
| down_write(&keyring->sem); |
| |
| klist = keyring->payload.subscriptions; |
| if (!klist) |
| goto no_klist; |
| |
| /* work out how many subscriptions we're keeping */ |
| keep = 0; |
| for (loop = klist->nkeys - 1; loop >= 0; loop--) |
| if (!key_is_dead(klist->keys[loop], limit)) |
| keep++; |
| |
| if (keep == klist->nkeys) |
| goto just_return; |
| |
| /* allocate a new keyring payload */ |
| max = roundup(keep, 4); |
| new = kmalloc(sizeof(struct keyring_list) + max * sizeof(struct key *), |
| GFP_KERNEL); |
| if (!new) |
| goto nomem; |
| new->maxkeys = max; |
| new->nkeys = 0; |
| new->delkey = 0; |
| |
| /* install the live keys |
| * - must take care as expired keys may be updated back to life |
| */ |
| keep = 0; |
| for (loop = klist->nkeys - 1; loop >= 0; loop--) { |
| key = klist->keys[loop]; |
| if (!key_is_dead(key, limit)) { |
| if (keep >= max) |
| goto discard_new; |
| new->keys[keep++] = key_get(key); |
| } |
| } |
| new->nkeys = keep; |
| |
| /* adjust the quota */ |
| key_payload_reserve(keyring, |
| sizeof(struct keyring_list) + |
| KEYQUOTA_LINK_BYTES * keep); |
| |
| if (keep == 0) { |
| rcu_assign_pointer(keyring->payload.subscriptions, NULL); |
| kfree(new); |
| } else { |
| rcu_assign_pointer(keyring->payload.subscriptions, new); |
| } |
| |
| up_write(&keyring->sem); |
| |
| call_rcu(&klist->rcu, keyring_clear_rcu_disposal); |
| kleave(" [yes]"); |
| return; |
| |
| discard_new: |
| new->nkeys = keep; |
| keyring_clear_rcu_disposal(&new->rcu); |
| up_write(&keyring->sem); |
| kleave(" [discard]"); |
| return; |
| |
| just_return: |
| up_write(&keyring->sem); |
| kleave(" [no dead]"); |
| return; |
| |
| no_klist: |
| up_write(&keyring->sem); |
| kleave(" [no_klist]"); |
| return; |
| |
| nomem: |
| up_write(&keyring->sem); |
| kleave(" [oom]"); |
| } |