/* Keyring handling * * Copyright (C) 2004-2005, 2008, 2013 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 #include #include #include #include #include #include #include #include #include #include #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) /* * We mark pointers we pass to the associative array with bit 1 set if * they're keyrings and clear otherwise. */ #define KEYRING_PTR_SUBTYPE 0x2UL static inline bool keyring_ptr_is_keyring(const struct assoc_array_ptr *x) { return (unsigned long)x & KEYRING_PTR_SUBTYPE; } static inline struct key *keyring_ptr_to_key(const struct assoc_array_ptr *x) { void *object = assoc_array_ptr_to_leaf(x); return (struct key *)((unsigned long)object & ~KEYRING_PTR_SUBTYPE); } static inline void *keyring_key_to_ptr(struct key *key) { if (key->type == &key_type_keyring) return (void *)((unsigned long)key | KEYRING_PTR_SUBTYPE); return key; } 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 key type definition. Keyrings are simply keys of this type and * can be treated as ordinary keys in addition to having their own special * operations. */ static int keyring_instantiate(struct key *keyring, struct key_preparsed_payload *prep); 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 = 0, .instantiate = keyring_instantiate, .match = user_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); } } /* * Initialise a keyring. * * Returns 0 on success, -EINVAL if given any data. */ static int keyring_instantiate(struct key *keyring, struct key_preparsed_payload *prep) { int ret; ret = -EINVAL; if (prep->datalen == 0) { assoc_array_init(&keyring->keys); /* make the keyring available by name if it has one */ keyring_publish_name(keyring); ret = 0; } return ret; } /* * Multiply 64-bits by 32-bits to 96-bits and fold back to 64-bit. Ideally we'd * fold the carry back too, but that requires inline asm. */ static u64 mult_64x32_and_fold(u64 x, u32 y) { u64 hi = (u64)(u32)(x >> 32) * y; u64 lo = (u64)(u32)(x) * y; return lo + ((u64)(u32)hi << 32) + (u32)(hi >> 32); } /* * Hash a key type and description. */ static unsigned long hash_key_type_and_desc(const struct keyring_index_key *index_key) { const unsigned level_shift = ASSOC_ARRAY_LEVEL_STEP; const unsigned long level_mask = ASSOC_ARRAY_LEVEL_STEP_MASK; const char *description = index_key->description; unsigned long hash, type; u32 piece; u64 acc; int n, desc_len = index_key->desc_len; type = (unsigned long)index_key->type; acc = mult_64x32_and_fold(type, desc_len + 13); acc = mult_64x32_and_fold(acc, 9207); for (;;) { n = desc_len; if (n <= 0) break; if (n > 4) n = 4; piece = 0; memcpy(&piece, description, n); description += n; desc_len -= n; acc = mult_64x32_and_fold(acc, piece); acc = mult_64x32_and_fold(acc, 9207); } /* Fold the hash down to 32 bits if need be. */ hash = acc; if (ASSOC_ARRAY_KEY_CHUNK_SIZE == 32) hash ^= acc >> 32; /* Squidge all the keyrings into a separate part of the tree to * ordinary keys by making sure the lowest level segment in the hash is * zero for keyrings and non-zero otherwise. */ if (index_key->type != &key_type_keyring && (hash & level_mask) == 0) return hash | (hash >> (ASSOC_ARRAY_KEY_CHUNK_SIZE - level_shift)) | 1; if (index_key->type == &key_type_keyring && (hash & level_mask) != 0) return (hash + (hash << level_shift)) & ~level_mask; return hash; } /* * Build the next index key chunk. * * On 32-bit systems the index key is laid out as: * * 0 4 5 9... * hash desclen typeptr desc[] * * On 64-bit systems: * * 0 8 9 17... * hash desclen typeptr desc[] * * We return it one word-sized chunk at a time. */ static unsigned long keyring_get_key_chunk(const void *data, int level) { const struct keyring_index_key *index_key = data; unsigned long chunk = 0; long offset = 0; int desc_len = index_key->desc_len, n = sizeof(chunk); level /= ASSOC_ARRAY_KEY_CHUNK_SIZE; switch (level) { case 0: return hash_key_type_and_desc(index_key); case 1: return ((unsigned long)index_key->type << 8) | desc_len; case 2: if (desc_len == 0) return (u8)((unsigned long)index_key->type >> (ASSOC_ARRAY_KEY_CHUNK_SIZE - 8)); n--; offset = 1; default: offset += sizeof(chunk) - 1; offset += (level - 3) * sizeof(chunk); if (offset >= desc_len) return 0; desc_len -= offset; if (desc_len > n) desc_len = n; offset += desc_len; do { chunk <<= 8; chunk |= ((u8*)index_key->description)[--offset]; } while (--desc_len > 0); if (level == 2) { chunk <<= 8; chunk |= (u8)((unsigned long)index_key->type >> (ASSOC_ARRAY_KEY_CHUNK_SIZE - 8)); } return chunk; } } static unsigned long keyring_get_object_key_chunk(const void *object, int level) { const struct key *key = keyring_ptr_to_key(object); return keyring_get_key_chunk(&key->index_key, level); } static bool keyring_compare_object(const void *object, const void *data) { const struct keyring_index_key *index_key = data; const struct key *key = keyring_ptr_to_key(object); return key->index_key.type == index_key->type && key->index_key.desc_len == index_key->desc_len && memcmp(key->index_key.description, index_key->description, index_key->desc_len) == 0; } /* * Compare the index keys of a pair of objects and determine the bit position * at which they differ - if they differ. */ static int keyring_diff_objects(const void *_a, const void *_b) { const struct key *key_a = keyring_ptr_to_key(_a); const struct key *key_b = keyring_ptr_to_key(_b); const struct keyring_index_key *a = &key_a->index_key; const struct keyring_index_key *b = &key_b->index_key; unsigned long seg_a, seg_b; int level, i; level = 0; seg_a = hash_key_type_and_desc(a); seg_b = hash_key_type_and_desc(b); if ((seg_a ^ seg_b) != 0) goto differ; /* The number of bits contributed by the hash is controlled by a * constant in the assoc_array headers. Everything else thereafter we * can deal with as being machine word-size dependent. */ level += ASSOC_ARRAY_KEY_CHUNK_SIZE / 8; seg_a = a->desc_len; seg_b = b->desc_len; if ((seg_a ^ seg_b) != 0) goto differ; /* The next bit may not work on big endian */ level++; seg_a = (unsigned long)a->type; seg_b = (unsigned long)b->type; if ((seg_a ^ seg_b) != 0) goto differ; level += sizeof(unsigned long); if (a->desc_len == 0) goto same; i = 0; if (((unsigned long)a->description | (unsigned long)b->description) & (sizeof(unsigned long) - 1)) { do { seg_a = *(unsigned long *)(a->description + i); seg_b = *(unsigned long *)(b->description + i); if ((seg_a ^ seg_b) != 0) goto differ_plus_i; i += sizeof(unsigned long); } while (i < (a->desc_len & (sizeof(unsigned long) - 1))); } for (; i < a->desc_len; i++) { seg_a = *(unsigned char *)(a->description + i); seg_b = *(unsigned char *)(b->description + i); if ((seg_a ^ seg_b) != 0) goto differ_plus_i; } same: return -1; differ_plus_i: level += i; differ: i = level * 8 + __ffs(seg_a ^ seg_b); return i; } /* * Free an object after stripping the keyring flag off of the pointer. */ static void keyring_free_object(void *object) { key_put(keyring_ptr_to_key(object)); } /* * Operations for keyring management by the index-tree routines. */ static const struct assoc_array_ops keyring_assoc_array_ops = { .get_key_chunk = keyring_get_key_chunk, .get_object_key_chunk = keyring_get_object_key_chunk, .compare_object = keyring_compare_object, .diff_objects = keyring_diff_objects, .free_object = keyring_free_object, }; /* * Clean up a keyring when it is destroyed. Unpublish its name if it had one * and dispose of its data. * * The garbage collector detects the final key_put(), removes the keyring from * the serial number tree and then does RCU synchronisation before coming here, * so we shouldn't need to worry about code poking around here with the RCU * readlock held by this time. */ static void keyring_destroy(struct key *keyring) { 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); } assoc_array_destroy(&keyring->keys, &keyring_assoc_array_ops); } /* * Describe a keyring for /proc. */ static void keyring_describe(const struct key *keyring, struct seq_file *m) { if (keyring->description) seq_puts(m, keyring->description); else seq_puts(m, "[anon]"); if (key_is_instantiated(keyring)) { if (keyring->keys.nr_leaves_on_tree != 0) seq_printf(m, ": %lu", keyring->keys.nr_leaves_on_tree); else seq_puts(m, ": empty"); } } struct keyring_read_iterator_context { size_t qty; size_t count; key_serial_t __user *buffer; }; static int keyring_read_iterator(const void *object, void *data) { struct keyring_read_iterator_context *ctx = data; const struct key *key = keyring_ptr_to_key(object); int ret; kenter("{%s,%d},,{%zu/%zu}", key->type->name, key->serial, ctx->count, ctx->qty); if (ctx->count >= ctx->qty) return 1; ret = put_user(key->serial, ctx->buffer); if (ret < 0) return ret; ctx->buffer++; ctx->count += sizeof(key->serial); return 0; } /* * Read a list of key IDs from the keyring's contents in binary form * * The keyring's semaphore is read-locked by the caller. This prevents someone * from modifying it under us - which could cause us to read key IDs multiple * times. */ static long keyring_read(const struct key *keyring, char __user *buffer, size_t buflen) { struct keyring_read_iterator_context ctx; unsigned long nr_keys; int ret; kenter("{%d},,%zu", key_serial(keyring), buflen); if (buflen & (sizeof(key_serial_t) - 1)) return -EINVAL; nr_keys = keyring->keys.nr_leaves_on_tree; if (nr_keys == 0) return 0; /* Calculate how much data we could return */ ctx.qty = nr_keys * sizeof(key_serial_t); if (!buffer || !buflen) return ctx.qty; if (buflen > ctx.qty) ctx.qty = buflen; /* Copy the IDs of the subscribed keys into the buffer */ ctx.buffer = (key_serial_t __user *)buffer; ctx.count = 0; ret = assoc_array_iterate(&keyring->keys, keyring_read_iterator, &ctx); if (ret < 0) { kleave(" = %d [iterate]", ret); return ret; } kleave(" = %zu [ok]", ctx.count); return ctx.count; } /* * Allocate a keyring and link into the destination keyring. */ struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid, const struct cred *cred, key_perm_t perm, unsigned long flags, struct key *dest) { struct key *keyring; int ret; keyring = key_alloc(&key_type_keyring, description, uid, gid, cred, perm, 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; } EXPORT_SYMBOL(keyring_alloc); /* * Iteration function to consider each key found. */ static int keyring_search_iterator(const void *object, void *iterator_data) { struct keyring_search_context *ctx = iterator_data; const struct key *key = keyring_ptr_to_key(object); unsigned long kflags = key->flags; kenter("{%d}", key->serial); /* ignore keys not of this type */ if (key->type != ctx->index_key.type) { kleave(" = 0 [!type]"); return 0; } /* skip invalidated, revoked and expired keys */ if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) { if (kflags & ((1 << KEY_FLAG_INVALIDATED) | (1 << KEY_FLAG_REVOKED))) { ctx->result = ERR_PTR(-EKEYREVOKED); kleave(" = %d [invrev]", ctx->skipped_ret); goto skipped; } if (key->expiry && ctx->now.tv_sec >= key->expiry) { ctx->result = ERR_PTR(-EKEYEXPIRED); kleave(" = %d [expire]", ctx->skipped_ret); goto skipped; } } /* keys that don't match */ if (!ctx->match(key, ctx->match_data)) { kleave(" = 0 [!match]"); return 0; } /* key must have search permissions */ if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) && key_task_permission(make_key_ref(key, ctx->possessed), ctx->cred, KEY_SEARCH) < 0) { ctx->result = ERR_PTR(-EACCES); kleave(" = %d [!perm]", ctx->skipped_ret); goto skipped; } if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) { /* we set a different error code if we pass a negative key */ if (kflags & (1 << KEY_FLAG_NEGATIVE)) { smp_rmb(); ctx->result = ERR_PTR(key->type_data.reject_error); kleave(" = %d [neg]", ctx->skipped_ret); goto skipped; } } /* Found */ ctx->result = make_key_ref(key, ctx->possessed); kleave(" = 1 [found]"); return 1; skipped: return ctx->skipped_ret; } /* * Search inside a keyring for a key. We can search by walking to it * directly based on its index-key or we can iterate over the entire * tree looking for it, based on the match function. */ static int search_keyring(struct key *keyring, struct keyring_search_context *ctx) { if ((ctx->flags & KEYRING_SEARCH_LOOKUP_TYPE) == KEYRING_SEARCH_LOOKUP_DIRECT) { const void *object; object = assoc_array_find(&keyring->keys, &keyring_assoc_array_ops, &ctx->index_key); return object ? ctx->iterator(object, ctx) : 0; } return assoc_array_iterate(&keyring->keys, ctx->iterator, ctx); } /* * Search a tree of keyrings that point to other keyrings up to the maximum * depth. */ static bool search_nested_keyrings(struct key *keyring, struct keyring_search_context *ctx) { struct { struct key *keyring; struct assoc_array_node *node; int slot; } stack[KEYRING_SEARCH_MAX_DEPTH]; struct assoc_array_shortcut *shortcut; struct assoc_array_node *node; struct assoc_array_ptr *ptr; struct key *key; int sp = 0, slot; kenter("{%d},{%s,%s}", keyring->serial, ctx->index_key.type->name, ctx->index_key.description); if (ctx->index_key.description) ctx->index_key.desc_len = strlen(ctx->index_key.description); /* Check to see if this top-level keyring is what we are looking for * and whether it is valid or not. */ if (ctx->flags & KEYRING_SEARCH_LOOKUP_ITERATE || keyring_compare_object(keyring, &ctx->index_key)) { ctx->skipped_ret = 2; ctx->flags |= KEYRING_SEARCH_DO_STATE_CHECK; switch (ctx->iterator(keyring_key_to_ptr(keyring), ctx)) { case 1: goto found; case 2: return false; default: break; } } ctx->skipped_ret = 0; if (ctx->flags & KEYRING_SEARCH_NO_STATE_CHECK) ctx->flags &= ~KEYRING_SEARCH_DO_STATE_CHECK; /* Start processing a new keyring */ descend_to_keyring: kdebug("descend to %d", keyring->serial); if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) | (1 << KEY_FLAG_REVOKED))) goto not_this_keyring; /* Search through the keys in this keyring before its searching its * subtrees. */ if (search_keyring(keyring, ctx)) goto found; /* Then manually iterate through the keyrings nested in this one. * * Start from the root node of the index tree. Because of the way the * hash function has been set up, keyrings cluster on the leftmost * branch of the root node (root slot 0) or in the root node itself. * Non-keyrings avoid the leftmost branch of the root entirely (root * slots 1-15). */ ptr = ACCESS_ONCE(keyring->keys.root); if (!ptr) goto not_this_keyring; if (assoc_array_ptr_is_shortcut(ptr)) { /* If the root is a shortcut, either the keyring only contains * keyring pointers (everything clusters behind root slot 0) or * doesn't contain any keyring pointers. */ shortcut = assoc_array_ptr_to_shortcut(ptr); smp_read_barrier_depends(); if ((shortcut->index_key[0] & ASSOC_ARRAY_FAN_MASK) != 0) goto not_this_keyring; ptr = ACCESS_ONCE(shortcut->next_node); node = assoc_array_ptr_to_node(ptr); goto begin_node; } node = assoc_array_ptr_to_node(ptr); smp_read_barrier_depends(); ptr = node->slots[0]; if (!assoc_array_ptr_is_meta(ptr)) goto begin_node; descend_to_node: /* Descend to a more distal node in this keyring's content tree and go * through that. */ kdebug("descend"); if (assoc_array_ptr_is_shortcut(ptr)) { shortcut = assoc_array_ptr_to_shortcut(ptr); smp_read_barrier_depends(); ptr = ACCESS_ONCE(shortcut->next_node); BUG_ON(!assoc_array_ptr_is_node(ptr)); node = assoc_array_ptr_to_node(ptr); } begin_node: kdebug("begin_node"); smp_read_barrier_depends(); slot = 0; ascend_to_node: /* Go through the slots in a node */ for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) { ptr = ACCESS_ONCE(node->slots[slot]); if (assoc_array_ptr_is_meta(ptr) && node->back_pointer) goto descend_to_node; if (!keyring_ptr_is_keyring(ptr)) continue; key = keyring_ptr_to_key(ptr); if (sp >= KEYRING_SEARCH_MAX_DEPTH) { if (ctx->flags & KEYRING_SEARCH_DETECT_TOO_DEEP) { ctx->result = ERR_PTR(-ELOOP); return false; } goto not_this_keyring; } /* Search a nested keyring */ if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) && key_task_permission(make_key_ref(key, ctx->possessed), ctx->cred, KEY_SEARCH) < 0) continue; /* stack the current position */ stack[sp].keyring = keyring; stack[sp].node = node; stack[sp].slot = slot; sp++; /* begin again with the new keyring */ keyring = key; goto descend_to_keyring; } /* We've dealt with all the slots in the current node, so now we need * to ascend to the parent and continue processing there. */ ptr = ACCESS_ONCE(node->back_pointer); slot = node->parent_slot; if (ptr && assoc_array_ptr_is_shortcut(ptr)) { shortcut = assoc_array_ptr_to_shortcut(ptr); smp_read_barrier_depends(); ptr = ACCESS_ONCE(shortcut->back_pointer); slot = shortcut->parent_slot; } if (!ptr) goto not_this_keyring; node = assoc_array_ptr_to_node(ptr); smp_read_barrier_depends(); slot++; /* If we've ascended to the root (zero backpointer), we must have just * finished processing the leftmost branch rather than the root slots - * so there can't be any more keyrings for us to find. */ if (node->back_pointer) { kdebug("ascend %d", slot); goto ascend_to_node; } /* The keyring we're looking at was disqualified or didn't contain a * matching key. */ not_this_keyring: kdebug("not_this_keyring %d", sp); if (sp <= 0) { kleave(" = false"); return false; } /* Resume the processing of a keyring higher up in the tree */ sp--; keyring = stack[sp].keyring; node = stack[sp].node; slot = stack[sp].slot + 1; kdebug("ascend to %d [%d]", keyring->serial, slot); goto ascend_to_node; /* We found a viable match */ found: key = key_ref_to_ptr(ctx->result); key_check(key); if (!(ctx->flags & KEYRING_SEARCH_NO_UPDATE_TIME)) { key->last_used_at = ctx->now.tv_sec; keyring->last_used_at = ctx->now.tv_sec; while (sp > 0) stack[--sp].keyring->last_used_at = ctx->now.tv_sec; } kleave(" = true"); return true; } /** * keyring_search_aux - Search a keyring tree for a key matching some criteria * @keyring_ref: A pointer to the keyring with possession indicator. * @ctx: The keyring search context. * * Search the supplied keyring tree for a key that matches the criteria given. * The root keyring and any linked keyrings must grant Search permission to the * caller to be searchable and keys can only be found if they too grant Search * to the caller. The possession flag on the root keyring pointer controls use * of the possessor bits in permissions checking of the entire tree. In * addition, the LSM gets to forbid keyring searches and key matches. * * The search is performed as a breadth-then-depth search up to the prescribed * limit (KEYRING_SEARCH_MAX_DEPTH). * * Keys are matched to the type provided and are then filtered by the match * function, which is given the description to use in any way it sees fit. The * match function may use any attributes of a key that it wishes to to * determine the match. Normally the match function from the key type would be * used. * * RCU can be used to prevent the keyring key lists from disappearing without * the need to take lots of locks. * * Returns a pointer to the found key and increments the key usage count if * successful; -EAGAIN if no matching keys were found, or if expired or revoked * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the * specified keyring wasn't a keyring. * * In the case of a successful return, the possession attribute from * @keyring_ref is propagated to the returned key reference. */ key_ref_t keyring_search_aux(key_ref_t keyring_ref, struct keyring_search_context *ctx) { struct key *keyring; long err; ctx->iterator = keyring_search_iterator; ctx->possessed = is_key_possessed(keyring_ref); ctx->result = ERR_PTR(-EAGAIN); keyring = key_ref_to_ptr(keyring_ref); key_check(keyring); if (keyring->type != &key_type_keyring) return ERR_PTR(-ENOTDIR); if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM)) { err = key_task_permission(keyring_ref, ctx->cred, KEY_SEARCH); if (err < 0) return ERR_PTR(err); } rcu_read_lock(); ctx->now = current_kernel_time(); if (search_nested_keyrings(keyring, ctx)) __key_get(key_ref_to_ptr(ctx->result)); rcu_read_unlock(); return ctx->result; } /** * keyring_search - Search the supplied keyring tree for a matching key * @keyring: The root of the keyring tree to be searched. * @type: The type of keyring we want to find. * @description: The name of the keyring we want to find. * * As keyring_search_aux() above, but using the current task's credentials and * type's default matching function and preferred search method. */ key_ref_t keyring_search(key_ref_t keyring, struct key_type *type, const char *description) { struct keyring_search_context ctx = { .index_key.type = type, .index_key.description = description, .cred = current_cred(), .match = type->match, .match_data = description, .flags = (type->def_lookup_type | KEYRING_SEARCH_DO_STATE_CHECK), }; if (!ctx.match) return ERR_PTR(-ENOKEY); return keyring_search_aux(keyring, &ctx); } EXPORT_SYMBOL(keyring_search); /* * Search the given keyring for a key that might be updated. * * The caller must guarantee that the keyring is a keyring and that the * permission is granted to modify the keyring as no check is made here. The * caller must also hold a lock on the keyring semaphore. * * Returns a pointer to the found key with usage count incremented if * successful and returns NULL if not found. Revoked and invalidated keys are * skipped over. * * If successful, the possession indicator is propagated from the keyring ref * to the returned key reference. */ key_ref_t find_key_to_update(key_ref_t keyring_ref, const struct keyring_index_key *index_key) { struct key *keyring, *key; const void *object; keyring = key_ref_to_ptr(keyring_ref); kenter("{%d},{%s,%s}", keyring->serial, index_key->type->name, index_key->description); object = assoc_array_find(&keyring->keys, &keyring_assoc_array_ops, index_key); if (object) goto found; kleave(" = NULL"); return NULL; found: key = keyring_ptr_to_key(object); if (key->flags & ((1 << KEY_FLAG_INVALIDATED) | (1 << KEY_FLAG_REVOKED))) { kleave(" = NULL [x]"); return NULL; } __key_get(key); kleave(" = {%d}", key->serial); return make_key_ref(key, is_key_possessed(keyring_ref)); } /* * Find a keyring with the specified name. * * All named keyrings in the current user namespace are searched, provided they * grant Search permission directly to the caller (unless this check is * skipped). Keyrings whose usage points have reached zero or who have been * revoked are skipped. * * Returns a pointer to the keyring with the keyring's refcount having being * incremented on success. -ENOKEY is returned if a key could not be found. */ 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 (!kuid_has_mapping(current_user_ns(), keyring->user->uid)) 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; keyring->last_used_at = current_kernel_time().tv_sec; goto out; } } keyring = ERR_PTR(-ENOKEY); out: read_unlock(&keyring_name_lock); return keyring; } static int keyring_detect_cycle_iterator(const void *object, void *iterator_data) { struct keyring_search_context *ctx = iterator_data; const struct key *key = keyring_ptr_to_key(object); kenter("{%d}", key->serial); BUG_ON(key != ctx->match_data); ctx->result = ERR_PTR(-EDEADLK); return 1; } /* * 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 keyring_search_context ctx = { .index_key = A->index_key, .match_data = A, .iterator = keyring_detect_cycle_iterator, .flags = (KEYRING_SEARCH_LOOKUP_DIRECT | KEYRING_SEARCH_NO_STATE_CHECK | KEYRING_SEARCH_NO_UPDATE_TIME | KEYRING_SEARCH_NO_CHECK_PERM | KEYRING_SEARCH_DETECT_TOO_DEEP), }; rcu_read_lock(); search_nested_keyrings(B, &ctx); rcu_read_unlock(); return PTR_ERR(ctx.result) == -EAGAIN ? 0 : PTR_ERR(ctx.result); } /* * Preallocate memory so that a key can be linked into to a keyring. */ int __key_link_begin(struct key *keyring, const struct keyring_index_key *index_key, struct assoc_array_edit **_edit) __acquires(&keyring->sem) __acquires(&keyring_serialise_link_sem) { struct assoc_array_edit *edit; int ret; kenter("%d,%s,%s,", keyring->serial, index_key->type->name, index_key->description); BUG_ON(index_key->desc_len == 0); if (keyring->type != &key_type_keyring) return -ENOTDIR; down_write(&keyring->sem); ret = -EKEYREVOKED; if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) goto error_krsem; /* serialise link/link calls to prevent parallel calls causing a cycle * when linking two keyring in opposite orders */ if (index_key->type == &key_type_keyring) down_write(&keyring_serialise_link_sem); /* 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 error_sem; /* Create an edit script that will insert/replace the key in the * keyring tree. */ edit = assoc_array_insert(&keyring->keys, &keyring_assoc_array_ops, index_key, NULL); if (IS_ERR(edit)) { ret = PTR_ERR(edit); goto error_quota; } *_edit = edit; kleave(" = 0"); return 0; error_quota: /* undo the quota changes */ key_payload_reserve(keyring, keyring->datalen - KEYQUOTA_LINK_BYTES); error_sem: if (index_key->type == &key_type_keyring) up_write(&keyring_serialise_link_sem); error_krsem: up_write(&keyring->sem); kleave(" = %d", ret); return ret; } /* * Check already instantiated keys aren't going to be a problem. * * The caller must have called __key_link_begin(). Don't need to call this for * keys that were created since __key_link_begin() was called. */ int __key_link_check_live_key(struct key *keyring, struct key *key) { if (key->type == &key_type_keyring) /* check that we aren't going to create a cycle by linking one * keyring to another */ return keyring_detect_cycle(keyring, key); return 0; } /* * Link a key into to a keyring. * * Must be called with __key_link_begin() having being called. Discards any * already extant link to matching key if there is one, so that each keyring * holds at most one link to any given key of a particular type+description * combination. */ void __key_link(struct key *key, struct assoc_array_edit **_edit) { __key_get(key); assoc_array_insert_set_object(*_edit, keyring_key_to_ptr(key)); assoc_array_apply_edit(*_edit); *_edit = NULL; } /* * Finish linking a key into to a keyring. * * Must be called with __key_link_begin() having being called. */ void __key_link_end(struct key *keyring, const struct keyring_index_key *index_key, struct assoc_array_edit *edit) __releases(&keyring->sem) __releases(&keyring_serialise_link_sem) { BUG_ON(index_key->type == NULL); kenter("%d,%s,", keyring->serial, index_key->type->name); if (index_key->type == &key_type_keyring) up_write(&keyring_serialise_link_sem); if (edit) { key_payload_reserve(keyring, keyring->datalen - KEYQUOTA_LINK_BYTES); assoc_array_cancel_edit(edit); } up_write(&keyring->sem); } /** * key_link - Link a key to a keyring * @keyring: The keyring to make the link in. * @key: The key to link to. * * Make a link in a keyring to a key, such that the keyring holds a reference * on that key and the key can potentially be found by searching that keyring. * * This function will write-lock the keyring's semaphore and will consume some * of the user's key data quota to hold the link. * * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is * full, -EDQUOT if there is insufficient key data quota remaining to add * another link or -ENOMEM if there's insufficient memory. * * It is assumed that the caller has checked that it is permitted for a link to * be made (the keyring should have Write permission and the key Link * permission). */ int key_link(struct key *keyring, struct key *key) { struct assoc_array_edit *edit; int ret; kenter("{%d,%d}", keyring->serial, atomic_read(&keyring->usage)); key_check(keyring); key_check(key); if (test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags) && !test_bit(KEY_FLAG_TRUSTED, &key->flags)) return -EPERM; ret = __key_link_begin(keyring, &key->index_key, &edit); if (ret == 0) { kdebug("begun {%d,%d}", keyring->serial, atomic_read(&keyring->usage)); ret = __key_link_check_live_key(keyring, key); if (ret == 0) __key_link(key, &edit); __key_link_end(keyring, &key->index_key, edit); } kleave(" = %d {%d,%d}", ret, keyring->serial, atomic_read(&keyring->usage)); return ret; } EXPORT_SYMBOL(key_link); /** * key_unlink - Unlink the first link to a key from a keyring. * @keyring: The keyring to remove the link from. * @key: The key the link is to. * * Remove a link from a keyring to a key. * * This function will write-lock the keyring's semaphore. * * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if * the key isn't linked to by the keyring or -ENOMEM if there's insufficient * memory. * * It is assumed that the caller has checked that it is permitted for a link to * be removed (the keyring should have Write permission; no permissions are * required on the key). */ int key_unlink(struct key *keyring, struct key *key) { struct assoc_array_edit *edit; int ret; key_check(keyring); key_check(key); if (keyring->type != &key_type_keyring) return -ENOTDIR; down_write(&keyring->sem); edit = assoc_array_delete(&keyring->keys, &keyring_assoc_array_ops, &key->index_key); if (IS_ERR(edit)) { ret = PTR_ERR(edit); goto error; } ret = -ENOENT; if (edit == NULL) goto error; assoc_array_apply_edit(edit); ret = 0; error: up_write(&keyring->sem); return ret; } EXPORT_SYMBOL(key_unlink); /** * keyring_clear - Clear a keyring * @keyring: The keyring to clear. * * Clear the contents of the specified keyring. * * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring. */ int keyring_clear(struct key *keyring) { struct assoc_array_edit *edit; int ret; if (keyring->type != &key_type_keyring) return -ENOTDIR; down_write(&keyring->sem); edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops); if (IS_ERR(edit)) { ret = PTR_ERR(edit); } else { if (edit) assoc_array_apply_edit(edit); key_payload_reserve(keyring, 0); ret = 0; } up_write(&keyring->sem); return ret; } EXPORT_SYMBOL(keyring_clear); /* * Dispose of the links from a revoked keyring. * * This is called with the key sem write-locked. */ static void keyring_revoke(struct key *keyring) { struct assoc_array_edit *edit; edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops); if (!IS_ERR(edit)) { if (edit) assoc_array_apply_edit(edit); key_payload_reserve(keyring, 0); } } static bool gc_iterator(void *object, void *iterator_data) { struct key *key = keyring_ptr_to_key(object); time_t *limit = iterator_data; if (key_is_dead(key, *limit)) return false; key_get(key); return true; } /* * Collect garbage from the contents of a keyring, replacing the old list with * a new one with the pointers all shuffled down. * * Dead keys are classed as oned that are flagged as being dead or are revoked, * expired or negative keys that were revoked or expired before the specified * limit. */ void keyring_gc(struct key *keyring, time_t limit) { kenter("{%x,%s}", key_serial(keyring), keyring->description); down_write(&keyring->sem); assoc_array_gc(&keyring->keys, &keyring_assoc_array_ops, gc_iterator, &limit); up_write(&keyring->sem); kleave(""); }