671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 1) // SPDX-License-Identifier: GPL-2.0
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 2) /*
7bf765dd8442d (Eric Biggers 2020-11-13 13:19:15 -0800 3) * fs-verity hash algorithms
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 4) *
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 5) * Copyright 2019 Google LLC
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 6) */
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 7)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 8) #include "fsverity_private.h"
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 9)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 10) #include <crypto/hash.h>
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 11) #include <linux/scatterlist.h>
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 12)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 13) /* The hash algorithms supported by fs-verity */
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 14) struct fsverity_hash_alg fsverity_hash_algs[] = {
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 15) [FS_VERITY_HASH_ALG_SHA256] = {
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 16) .name = "sha256",
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 17) .digest_size = SHA256_DIGEST_SIZE,
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 18) .block_size = SHA256_BLOCK_SIZE,
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 19) },
add890c9f9d2d (Eric Biggers 2019-07-22 09:26:23 -0700 20) [FS_VERITY_HASH_ALG_SHA512] = {
add890c9f9d2d (Eric Biggers 2019-07-22 09:26:23 -0700 21) .name = "sha512",
add890c9f9d2d (Eric Biggers 2019-07-22 09:26:23 -0700 22) .digest_size = SHA512_DIGEST_SIZE,
add890c9f9d2d (Eric Biggers 2019-07-22 09:26:23 -0700 23) .block_size = SHA512_BLOCK_SIZE,
add890c9f9d2d (Eric Biggers 2019-07-22 09:26:23 -0700 24) },
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 25) };
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 26)
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 27) static DEFINE_MUTEX(fsverity_hash_alg_init_mutex);
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 28)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 29) /**
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 30) * fsverity_get_hash_alg() - validate and prepare a hash algorithm
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 31) * @inode: optional inode for logging purposes
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 32) * @num: the hash algorithm number
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 33) *
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 34) * Get the struct fsverity_hash_alg for the given hash algorithm number, and
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 35) * ensure it has a hash transform ready to go. The hash transforms are
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 36) * allocated on-demand so that we don't waste resources unnecessarily, and
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 37) * because the crypto modules may be initialized later than fs/verity/.
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 38) *
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 39) * Return: pointer to the hash alg on success, else an ERR_PTR()
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 40) */
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 41) struct fsverity_hash_alg *fsverity_get_hash_alg(const struct inode *inode,
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 42) unsigned int num)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 43) {
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 44) struct fsverity_hash_alg *alg;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 45) struct crypto_ahash *tfm;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 46) int err;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 47)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 48) if (num >= ARRAY_SIZE(fsverity_hash_algs) ||
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 49) !fsverity_hash_algs[num].name) {
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 50) fsverity_warn(inode, "Unknown hash algorithm number: %u", num);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 51) return ERR_PTR(-EINVAL);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 52) }
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 53) alg = &fsverity_hash_algs[num];
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 54)
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 55) /* pairs with smp_store_release() below */
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 56) if (likely(smp_load_acquire(&alg->tfm) != NULL))
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 57) return alg;
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 58)
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 59) mutex_lock(&fsverity_hash_alg_init_mutex);
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 60)
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 61) if (alg->tfm != NULL)
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 62) goto out_unlock;
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 63)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 64) /*
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 65) * Using the shash API would make things a bit simpler, but the ahash
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 66) * API is preferable as it allows the use of crypto accelerators.
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 67) */
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 68) tfm = crypto_alloc_ahash(alg->name, 0, 0);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 69) if (IS_ERR(tfm)) {
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 70) if (PTR_ERR(tfm) == -ENOENT) {
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 71) fsverity_warn(inode,
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 72) "Missing crypto API support for hash algorithm \"%s\"",
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 73) alg->name);
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 74) alg = ERR_PTR(-ENOPKG);
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 75) goto out_unlock;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 76) }
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 77) fsverity_err(inode,
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 78) "Error allocating hash algorithm \"%s\": %ld",
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 79) alg->name, PTR_ERR(tfm));
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 80) alg = ERR_CAST(tfm);
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 81) goto out_unlock;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 82) }
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 83)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 84) err = -EINVAL;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 85) if (WARN_ON(alg->digest_size != crypto_ahash_digestsize(tfm)))
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 86) goto err_free_tfm;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 87) if (WARN_ON(alg->block_size != crypto_ahash_blocksize(tfm)))
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 88) goto err_free_tfm;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 89)
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 90) err = mempool_init_kmalloc_pool(&alg->req_pool, 1,
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 91) sizeof(struct ahash_request) +
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 92) crypto_ahash_reqsize(tfm));
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 93) if (err)
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 94) goto err_free_tfm;
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 95)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 96) pr_info("%s using implementation \"%s\"\n",
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 97) alg->name, crypto_ahash_driver_name(tfm));
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 98)
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 99) /* pairs with smp_load_acquire() above */
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 100) smp_store_release(&alg->tfm, tfm);
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 101) goto out_unlock;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 102)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 103) err_free_tfm:
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 104) crypto_free_ahash(tfm);
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 105) alg = ERR_PTR(err);
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 106) out_unlock:
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 107) mutex_unlock(&fsverity_hash_alg_init_mutex);
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 108) return alg;
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 109) }
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 110)
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 111) /**
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 112) * fsverity_alloc_hash_request() - allocate a hash request object
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 113) * @alg: the hash algorithm for which to allocate the request
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 114) * @gfp_flags: memory allocation flags
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 115) *
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 116) * This is mempool-backed, so this never fails if __GFP_DIRECT_RECLAIM is set in
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 117) * @gfp_flags. However, in that case this might need to wait for all
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 118) * previously-allocated requests to be freed. So to avoid deadlocks, callers
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 119) * must never need multiple requests at a time to make forward progress.
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 120) *
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 121) * Return: the request object on success; NULL on failure (but see above)
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 122) */
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 123) struct ahash_request *fsverity_alloc_hash_request(struct fsverity_hash_alg *alg,
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 124) gfp_t gfp_flags)
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 125) {
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 126) struct ahash_request *req = mempool_alloc(&alg->req_pool, gfp_flags);
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 127)
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 128) if (req)
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 129) ahash_request_set_tfm(req, alg->tfm);
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 130) return req;
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 131) }
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 132)
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 133) /**
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 134) * fsverity_free_hash_request() - free a hash request object
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 135) * @alg: the hash algorithm
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 136) * @req: the hash request object to free
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 137) */
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 138) void fsverity_free_hash_request(struct fsverity_hash_alg *alg,
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 139) struct ahash_request *req)
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 140) {
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 141) if (req) {
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 142) ahash_request_zero(req);
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 143) mempool_free(req, &alg->req_pool);
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 144) }
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 145) }
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 146)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 147) /**
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 148) * fsverity_prepare_hash_state() - precompute the initial hash state
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 149) * @alg: hash algorithm
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 150) * @salt: a salt which is to be prepended to all data to be hashed
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 151) * @salt_size: salt size in bytes, possibly 0
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 152) *
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 153) * Return: NULL if the salt is empty, otherwise the kmalloc()'ed precomputed
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 154) * initial hash state on success or an ERR_PTR() on failure.
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 155) */
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 156) const u8 *fsverity_prepare_hash_state(struct fsverity_hash_alg *alg,
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 157) const u8 *salt, size_t salt_size)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 158) {
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 159) u8 *hashstate = NULL;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 160) struct ahash_request *req = NULL;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 161) u8 *padded_salt = NULL;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 162) size_t padded_salt_size;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 163) struct scatterlist sg;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 164) DECLARE_CRYPTO_WAIT(wait);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 165) int err;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 166)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 167) if (salt_size == 0)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 168) return NULL;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 169)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 170) hashstate = kmalloc(crypto_ahash_statesize(alg->tfm), GFP_KERNEL);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 171) if (!hashstate)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 172) return ERR_PTR(-ENOMEM);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 173)
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 174) /* This allocation never fails, since it's mempool-backed. */
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 175) req = fsverity_alloc_hash_request(alg, GFP_KERNEL);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 176)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 177) /*
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 178) * Zero-pad the salt to the next multiple of the input size of the hash
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 179) * algorithm's compression function, e.g. 64 bytes for SHA-256 or 128
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 180) * bytes for SHA-512. This ensures that the hash algorithm won't have
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 181) * any bytes buffered internally after processing the salt, thus making
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 182) * salted hashing just as fast as unsalted hashing.
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 183) */
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 184) padded_salt_size = round_up(salt_size, alg->block_size);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 185) padded_salt = kzalloc(padded_salt_size, GFP_KERNEL);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 186) if (!padded_salt) {
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 187) err = -ENOMEM;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 188) goto err_free;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 189) }
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 190) memcpy(padded_salt, salt, salt_size);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 191)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 192) sg_init_one(&sg, padded_salt, padded_salt_size);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 193) ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP |
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 194) CRYPTO_TFM_REQ_MAY_BACKLOG,
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 195) crypto_req_done, &wait);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 196) ahash_request_set_crypt(req, &sg, NULL, padded_salt_size);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 197)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 198) err = crypto_wait_req(crypto_ahash_init(req), &wait);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 199) if (err)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 200) goto err_free;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 201)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 202) err = crypto_wait_req(crypto_ahash_update(req), &wait);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 203) if (err)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 204) goto err_free;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 205)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 206) err = crypto_ahash_export(req, hashstate);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 207) if (err)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 208) goto err_free;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 209) out:
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 210) fsverity_free_hash_request(alg, req);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 211) kfree(padded_salt);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 212) return hashstate;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 213)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 214) err_free:
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 215) kfree(hashstate);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 216) hashstate = ERR_PTR(err);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 217) goto out;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 218) }
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 219)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 220) /**
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 221) * fsverity_hash_page() - hash a single data or hash page
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 222) * @params: the Merkle tree's parameters
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 223) * @inode: inode for which the hashing is being done
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 224) * @req: preallocated hash request
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 225) * @page: the page to hash
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 226) * @out: output digest, size 'params->digest_size' bytes
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 227) *
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 228) * Hash a single data or hash block, assuming block_size == PAGE_SIZE.
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 229) * The hash is salted if a salt is specified in the Merkle tree parameters.
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 230) *
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 231) * Return: 0 on success, -errno on failure
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 232) */
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 233) int fsverity_hash_page(const struct merkle_tree_params *params,
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 234) const struct inode *inode,
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 235) struct ahash_request *req, struct page *page, u8 *out)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 236) {
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 237) struct scatterlist sg;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 238) DECLARE_CRYPTO_WAIT(wait);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 239) int err;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 240)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 241) if (WARN_ON(params->block_size != PAGE_SIZE))
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 242) return -EINVAL;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 243)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 244) sg_init_table(&sg, 1);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 245) sg_set_page(&sg, page, PAGE_SIZE, 0);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 246) ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP |
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 247) CRYPTO_TFM_REQ_MAY_BACKLOG,
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 248) crypto_req_done, &wait);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 249) ahash_request_set_crypt(req, &sg, out, PAGE_SIZE);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 250)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 251) if (params->hashstate) {
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 252) err = crypto_ahash_import(req, params->hashstate);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 253) if (err) {
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 254) fsverity_err(inode,
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 255) "Error %d importing hash state", err);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 256) return err;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 257) }
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 258) err = crypto_ahash_finup(req);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 259) } else {
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 260) err = crypto_ahash_digest(req);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 261) }
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 262)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 263) err = crypto_wait_req(err, &wait);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 264) if (err)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 265) fsverity_err(inode, "Error %d computing page hash", err);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 266) return err;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 267) }
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 268)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 269) /**
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 270) * fsverity_hash_buffer() - hash some data
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 271) * @alg: the hash algorithm to use
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 272) * @data: the data to hash
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 273) * @size: size of data to hash, in bytes
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 274) * @out: output digest, size 'alg->digest_size' bytes
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 275) *
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 276) * Hash some data which is located in physically contiguous memory (i.e. memory
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 277) * allocated by kmalloc(), not by vmalloc()). No salt is used.
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 278) *
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 279) * Return: 0 on success, -errno on failure
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 280) */
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 281) int fsverity_hash_buffer(struct fsverity_hash_alg *alg,
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 282) const void *data, size_t size, u8 *out)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 283) {
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 284) struct ahash_request *req;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 285) struct scatterlist sg;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 286) DECLARE_CRYPTO_WAIT(wait);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 287) int err;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 288)
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 289) /* This allocation never fails, since it's mempool-backed. */
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 290) req = fsverity_alloc_hash_request(alg, GFP_KERNEL);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 291)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 292) sg_init_one(&sg, data, size);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 293) ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP |
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 294) CRYPTO_TFM_REQ_MAY_BACKLOG,
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 295) crypto_req_done, &wait);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 296) ahash_request_set_crypt(req, &sg, out, size);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 297)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 298) err = crypto_wait_req(crypto_ahash_digest(req), &wait);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 299)
439bea104c3d2 (Eric Biggers 2019-12-31 11:55:45 -0600 300) fsverity_free_hash_request(alg, req);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 301) return err;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 302) }
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 303)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 304) void __init fsverity_check_hash_algs(void)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 305) {
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 306) size_t i;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 307)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 308) /*
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 309) * Sanity check the hash algorithms (could be a build-time check, but
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 310) * they're in an array)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 311) */
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 312) for (i = 0; i < ARRAY_SIZE(fsverity_hash_algs); i++) {
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 313) const struct fsverity_hash_alg *alg = &fsverity_hash_algs[i];
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 314)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 315) if (!alg->name)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 316) continue;
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 317)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 318) BUG_ON(alg->digest_size > FS_VERITY_MAX_DIGEST_SIZE);
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 319)
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 320) /*
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 321) * For efficiency, the implementation currently assumes the
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 322) * digest and block sizes are powers of 2. This limitation can
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 323) * be lifted if the code is updated to handle other values.
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 324) */
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 325) BUG_ON(!is_power_of_2(alg->digest_size));
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 326) BUG_ON(!is_power_of_2(alg->block_size));
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 327) }
671e67b47e9ff (Eric Biggers 2019-07-22 09:26:21 -0700 328) }
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