| /* 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->name_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->name_link.next != NULL && |
| !list_empty(&keyring->name_link)) |
| list_del(&keyring->name_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, |
| key_restrict_link_func_t restrict_link, |
| struct key *dest) |
| { |
| struct key *keyring; |
| int ret; |
| |
| keyring = key_alloc(&key_type_keyring, description, |
| uid, gid, cred, perm, flags, restrict_link); |
| 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); |
| |
| /** |
| * restrict_link_reject - Give -EPERM to restrict link |
| * @keyring: The keyring being added to. |
| * @type: The type of key being added. |
| * @payload: The payload of the key intended to be added. |
| * @data: Additional data for evaluating restriction. |
| * |
| * Reject the addition of any links to a keyring. It can be overridden by |
| * passing KEY_ALLOC_BYPASS_RESTRICTION to key_instantiate_and_link() when |
| * adding a key to a keyring. |
| * |
| * This is meant to be passed as the restrict_link parameter to |
| * keyring_alloc(). |
| */ |
| int restrict_link_reject(struct key *keyring, |
| const struct key_type *type, |
| const union key_payload *payload, |
| struct key *restriction_key) |
| { |
| return -EPERM; |
| } |
| |
| /* |
| * 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->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], |
| name_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 (!refcount_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); |
| } |
| |
| /* |
| * Check addition of keys to restricted keyrings. |
| */ |
| static int __key_link_check_restriction(struct key *keyring, struct key *key) |
| { |
| if (!keyring->restrict_link) |
| return 0; |
| return keyring->restrict_link(keyring, key->type, &key->payload, NULL); |
| } |
| |
| /** |
| * 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, refcount_read(&keyring->usage)); |
| |
| key_check(keyring); |
| key_check(key); |
| |
| ret = __key_link_begin(keyring, &key->index_key, &edit); |
| if (ret == 0) { |
| kdebug("begun {%d,%d}", keyring->serial, refcount_read(&keyring->usage)); |
| ret = __key_link_check_restriction(keyring, key); |
| if (ret == 0) |
| 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, refcount_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]"); |
| } |