diff options
Diffstat (limited to 'security/keys/keyring.c')
| -rw-r--r-- | security/keys/keyring.c | 1396 |
1 files changed, 1396 insertions, 0 deletions
diff --git a/security/keys/keyring.c b/security/keys/keyring.c new file mode 100644 index 000000000..d33437007 --- /dev/null +++ b/security/keys/keyring.c @@ -0,0 +1,1396 @@ +/* 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 <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 <keys/user-type.h> +#include <linux/assoc_array_priv.h> +#include <linux/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) + +/* + * 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_preparse(struct key_preparsed_payload *prep); +static void keyring_free_preparse(struct key_preparsed_payload *prep); +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, + .preparse = keyring_preparse, + .free_preparse = keyring_free_preparse, + .instantiate = keyring_instantiate, + .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); + } +} + +/* + * Preparse a keyring payload + */ +static int keyring_preparse(struct key_preparsed_payload *prep) +{ + return prep->datalen != 0 ? -EINVAL : 0; +} + +/* + * Free a preparse of a user defined key payload + */ +static void keyring_free_preparse(struct key_preparsed_payload *prep) +{ +} + +/* + * Initialise a keyring. + * + * Returns 0 on success, -EINVAL if given any data. + */ +static int keyring_instantiate(struct key *keyring, + struct key_preparsed_payload *prep) +{ + assoc_array_init(&keyring->keys); + /* make the keyring available by name if it has one */ + keyring_publish_name(keyring); + return 0; +} + +/* + * 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 fan_mask = ASSOC_ARRAY_FAN_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 & fan_mask) == 0) + return hash | (hash >> (ASSOC_ARRAY_KEY_CHUNK_SIZE - level_shift)) | 1; + if (index_key->type == &key_type_keyring && (hash & fan_mask) != 0) + return (hash + (hash << level_shift)) & ~fan_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 *object, const void *data) +{ + const struct key *key_a = keyring_ptr_to_key(object); + const struct keyring_index_key *a = &key_a->index_key; + const struct keyring_index_key *b = data; + 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); + +/* + * By default, we keys found by getting an exact match on their descriptions. + */ +bool key_default_cmp(const struct key *key, + const struct key_match_data *match_data) +{ + return strcmp(key->description, match_data->raw_data) == 0; +} + +/* + * 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) { + if (!(ctx->flags & KEYRING_SEARCH_SKIP_EXPIRED)) + ctx->result = ERR_PTR(-EKEYEXPIRED); + kleave(" = %d [expire]", ctx->skipped_ret); + goto skipped; + } + } + + /* keys that don't match */ + if (!ctx->match_data.cmp(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_NEED_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->match_data.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); + +#define STATE_CHECKS (KEYRING_SEARCH_NO_STATE_CHECK | KEYRING_SEARCH_DO_STATE_CHECK) + BUG_ON((ctx->flags & STATE_CHECKS) == 0 || + (ctx->flags & STATE_CHECKS) == STATE_CHECKS); + + 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->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_ITERATE || + keyring_compare_object(keyring, &ctx->index_key)) { + ctx->skipped_ret = 2; + switch (ctx->iterator(keyring_key_to_ptr(keyring), ctx)) { + case 1: + goto found; + case 2: + return false; + default: + break; + } + } + + ctx->skipped_ret = 0; + + /* 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_NEED_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_NEED_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_data.cmp = key_default_cmp, + .match_data.raw_data = description, + .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT, + .flags = KEYRING_SEARCH_DO_STATE_CHECK, + }; + key_ref_t key; + int ret; + + if (type->match_preparse) { + ret = type->match_preparse(&ctx.match_data); + if (ret < 0) + return ERR_PTR(ret); + } + + key = keyring_search_aux(keyring, &ctx); + + if (type->match_free) + type->match_free(&ctx.match_data); + return key; +} +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_NEED_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); + + /* We might get a keyring with matching index-key that is nonetheless a + * different keyring. */ + if (key != ctx->match_data.raw_data) + return 0; + + 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.raw_data = A, + .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT, + .iterator = keyring_detect_cycle_iterator, + .flags = (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); + + /* 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_sem; + } + + /* If we're not replacing a link in-place then we're going to need some + * extra quota. + */ + if (!edit->dead_leaf) { + ret = key_payload_reserve(keyring, + keyring->datalen + KEYQUOTA_LINK_BYTES); + if (ret < 0) + goto error_cancel; + } + + *_edit = edit; + kleave(" = 0"); + return 0; + +error_cancel: + assoc_array_cancel_edit(edit); +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) { + if (!edit->dead_leaf) { + 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); + key_payload_reserve(keyring, keyring->datalen - KEYQUOTA_LINK_BYTES); + 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 keyring_gc_select_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; +} + +static int keyring_gc_check_iterator(const void *object, void *iterator_data) +{ + const struct key *key = keyring_ptr_to_key(object); + time_t *limit = iterator_data; + + key_check(key); + return key_is_dead(key, *limit); +} + +/* + * Garbage collect pointers from a keyring. + * + * Not called with any locks held. The keyring's key struct will not be + * deallocated under us as only our caller may deallocate it. + */ +void keyring_gc(struct key *keyring, time_t limit) +{ + int result; + + kenter("%x{%s}", keyring->serial, keyring->description ?: ""); + + if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) | + (1 << KEY_FLAG_REVOKED))) + goto dont_gc; + + /* scan the keyring looking for dead keys */ + rcu_read_lock(); + result = assoc_array_iterate(&keyring->keys, + keyring_gc_check_iterator, &limit); + rcu_read_unlock(); + if (result == true) + goto do_gc; + +dont_gc: + kleave(" [no gc]"); + return; + +do_gc: + down_write(&keyring->sem); + assoc_array_gc(&keyring->keys, &keyring_assoc_array_ops, + keyring_gc_select_iterator, &limit); + up_write(&keyring->sem); + kleave(" [gc]"); +} |