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Merge pull request #20915 from bluca/libsystemd_openssl

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libsystemd/sd-id128: use only internal hmac, remove khash/OpenSSL support
This commit is contained in:
Luca Boccassi
2021-10-09 18:37:59 +01:00
committed by GitHub
parent af7fb6831f ee6df1fdd4
commit ccf609c88c
22 changed files with 301 additions and 577 deletions
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src/basic/hmac.c
+62
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@@ -0,0 +1,62 @@
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <assert.h>
#include <string.h>
#include "hmac.h"
#include "sha256.h"
#define HMAC_BLOCK_SIZE 64
#define INNER_PADDING_BYTE 0x36
#define OUTER_PADDING_BYTE 0x5c
void hmac_sha256(const void *key,
size_t key_size,
const void *input,
size_t input_size,
uint8_t res[static SHA256_DIGEST_SIZE]) {
uint8_t inner_padding[HMAC_BLOCK_SIZE] = { };
uint8_t outer_padding[HMAC_BLOCK_SIZE] = { };
uint8_t replacement_key[SHA256_DIGEST_SIZE];
struct sha256_ctx hash;
assert(key);
assert(key_size > 0);
assert(res);
/* Implement algorithm as described by FIPS 198. */
/* The key needs to be block size length or less, hash it if it's longer. */
if (key_size > HMAC_BLOCK_SIZE) {
sha256_init_ctx(&hash);
sha256_process_bytes(key, key_size, &hash);
sha256_finish_ctx(&hash, replacement_key);
key = replacement_key;
key_size = SHA256_DIGEST_SIZE;
}
/* First, copy the key into the padding arrays. If it's shorter than
* the block size, the arrays are already initialized to 0. */
memcpy(inner_padding, key, key_size);
memcpy(outer_padding, key, key_size);
/* Then, XOR the provided key and any padding leftovers with the fixed
* padding bytes as defined in FIPS 198. */
for (size_t i = 0; i < HMAC_BLOCK_SIZE; i++) {
inner_padding[i] ^= INNER_PADDING_BYTE;
outer_padding[i] ^= OUTER_PADDING_BYTE;
}
/* First pass: hash the inner padding array and the input. */
sha256_init_ctx(&hash);
sha256_process_bytes(inner_padding, HMAC_BLOCK_SIZE, &hash);
sha256_process_bytes(input, input_size, &hash);
sha256_finish_ctx(&hash, res);
/* Second pass: hash the outer padding array and the result of the first pass. */
sha256_init_ctx(&hash);
sha256_process_bytes(outer_padding, HMAC_BLOCK_SIZE, &hash);
sha256_process_bytes(res, SHA256_DIGEST_SIZE, &hash);
sha256_finish_ctx(&hash, res);
}
src/basic/hmac.h
+12
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@@ -0,0 +1,12 @@
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#pragma once
#include <stdint.h>
#include <stdlib.h>
#define SHA256_DIGEST_SIZE 32
/* Unoptimized implementation based on FIPS 198. 'res' has to be allocated by
* the caller. Prefer external OpenSSL functions, and use this only when
* linking to OpenSSL is not desireable (eg: libsystemd.so). */
void hmac_sha256(const void *key, size_t key_size, const void *input, size_t input_size, uint8_t res[static SHA256_DIGEST_SIZE]);
src/basic/khash.c
-321
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@@ -1,321 +0,0 @@
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <linux/if_alg.h>
#include <stdbool.h>
#include <sys/socket.h>
#include "alloc-util.h"
#include "fd-util.h"
#include "hexdecoct.h"
#include "khash.h"
#include "macro.h"
#include "missing_socket.h"
#include "string-util.h"
#include "util.h"
/* On current kernels the maximum digest (according to "grep digestsize /proc/crypto | sort -u") is actually 32, but
* let's add some extra room, the few wasted bytes don't really matter... */
#define LONGEST_DIGEST 128
struct khash {
int fd;
char *algorithm;
uint8_t digest[LONGEST_DIGEST+1];
size_t digest_size;
bool digest_valid;
};
int khash_supported(void) {
static const union {
struct sockaddr sa;
struct sockaddr_alg alg;
} sa = {
.alg.salg_family = AF_ALG,
.alg.salg_type = "hash",
.alg.salg_name = "sha256", /* a very common algorithm */
};
static int cached = -1;
if (cached < 0) {
_cleanup_close_ int fd1 = -1, fd2 = -1;
uint8_t buf[LONGEST_DIGEST+1];
fd1 = socket(AF_ALG, SOCK_SEQPACKET|SOCK_CLOEXEC, 0);
if (fd1 < 0) {
/* The kernel returns EAFNOSUPPORT if AF_ALG is not supported at all */
if (IN_SET(errno, EAFNOSUPPORT, EOPNOTSUPP))
return (cached = false);
return -errno;
}
if (bind(fd1, &sa.sa, sizeof(sa)) < 0) {
/* The kernel returns ENOENT if the selected algorithm is not supported at all. We use a check
* for SHA256 as a proxy for whether the whole API is supported at all. After all it's one of
* the most common hash functions, and if it isn't supported, that's ample indication that
* something is really off. */
if (IN_SET(errno, ENOENT, EOPNOTSUPP))
return (cached = false);
return -errno;
}
fd2 = accept4(fd1, NULL, 0, SOCK_CLOEXEC);
if (fd2 < 0) {
if (errno == EOPNOTSUPP)
return (cached = false);
return -errno;
}
if (recv(fd2, buf, sizeof(buf), 0) < 0) {
/* On some kernels we get ENOKEY for non-keyed hash functions (such as sha256), let's refuse
* using the API in those cases, since the kernel is
* broken. https://github.com/systemd/systemd/issues/8278 */
if (IN_SET(errno, ENOKEY, EOPNOTSUPP))
return (cached = false);
}
cached = true;
}
return cached;
}
int khash_new_with_key(khash **ret, const char *algorithm, const void *key, size_t key_size) {
union {
struct sockaddr sa;
struct sockaddr_alg alg;
} sa = {
.alg.salg_family = AF_ALG,
.alg.salg_type = "hash",
};
_cleanup_(khash_unrefp) khash *h = NULL;
_cleanup_close_ int fd = -1;
int supported;
ssize_t n;
assert(ret);
assert(key || key_size == 0);
/* Filter out an empty algorithm early, as we do not support an algorithm by that name. */
if (isempty(algorithm))
return -EINVAL;
/* Overly long hash algorithm names we definitely do not support */
if (strlen(algorithm) >= sizeof(sa.alg.salg_name))
return -EOPNOTSUPP;
supported = khash_supported();
if (supported < 0)
return supported;
if (supported == 0)
return -EOPNOTSUPP;
fd = socket(AF_ALG, SOCK_SEQPACKET|SOCK_CLOEXEC, 0);
if (fd < 0)
return -errno;
strcpy((char*) sa.alg.salg_name, algorithm);
if (bind(fd, &sa.sa, sizeof(sa)) < 0) {
if (errno == ENOENT)
return -EOPNOTSUPP;
return -errno;
}
if (key) {
if (setsockopt(fd, SOL_ALG, ALG_SET_KEY, key, key_size) < 0)
return -errno;
}
h = new0(khash, 1);
if (!h)
return -ENOMEM;
h->fd = accept4(fd, NULL, 0, SOCK_CLOEXEC);
if (h->fd < 0)
return -errno;
h->algorithm = strdup(algorithm);
if (!h->algorithm)
return -ENOMEM;
/* Temporary fix for rc kernel bug: https://bugzilla.redhat.com/show_bug.cgi?id=1395896 */
(void) send(h->fd, NULL, 0, 0);
/* Figure out the digest size */
n = recv(h->fd, h->digest, sizeof(h->digest), 0);
if (n < 0)
return -errno;
if (n >= LONGEST_DIGEST) /* longer than what we expected? If so, we don't support this */
return -EOPNOTSUPP;
h->digest_size = (size_t) n;
h->digest_valid = true;
/* Temporary fix for rc kernel bug: https://bugzilla.redhat.com/show_bug.cgi?id=1395896 */
(void) send(h->fd, NULL, 0, 0);
*ret = TAKE_PTR(h);
return 0;
}
int khash_new(khash **ret, const char *algorithm) {
return khash_new_with_key(ret, algorithm, NULL, 0);
}
khash* khash_unref(khash *h) {
if (!h)
return NULL;
safe_close(h->fd);
free(h->algorithm);
return mfree(h);
}
int khash_dup(khash *h, khash **ret) {
_cleanup_(khash_unrefp) khash *copy = NULL;
assert(h);
assert(ret);
copy = newdup(khash, h, 1);
if (!copy)
return -ENOMEM;
copy->fd = -1;
copy->algorithm = strdup(h->algorithm);
if (!copy->algorithm)
return -ENOMEM;
copy->fd = accept4(h->fd, NULL, 0, SOCK_CLOEXEC);
if (copy->fd < 0)
return -errno;
*ret = TAKE_PTR(copy);
return 0;
}
const char *khash_get_algorithm(khash *h) {
assert(h);
return h->algorithm;
}
size_t khash_get_size(khash *h) {
assert(h);
return h->digest_size;
}
int khash_reset(khash *h) {
ssize_t n;
assert(h);
n = send(h->fd, NULL, 0, 0);
if (n < 0)
return -errno;
h->digest_valid = false;
return 0;
}
int khash_put(khash *h, const void *buffer, size_t size) {
ssize_t n;
assert(h);
assert(buffer || size == 0);
if (size <= 0)
return 0;
n = send(h->fd, buffer, size, MSG_MORE);
if (n < 0)
return -errno;
h->digest_valid = false;
return 0;
}
int khash_put_iovec(khash *h, const struct iovec *iovec, size_t n) {
struct msghdr mh = {
.msg_iov = (struct iovec*) iovec,
.msg_iovlen = n,
};
ssize_t k;
assert(h);
assert(iovec || n == 0);
if (n <= 0)
return 0;
k = sendmsg(h->fd, &mh, MSG_MORE);
if (k < 0)
return -errno;
h->digest_valid = false;
return 0;
}
static int retrieve_digest(khash *h) {
ssize_t n;
assert(h);
if (h->digest_valid)
return 0;
n = recv(h->fd, h->digest, h->digest_size, 0);
if (n < 0)
return n;
if ((size_t) n != h->digest_size) /* digest size changed? */
return -EIO;
h->digest_valid = true;
return 0;
}
int khash_digest_data(khash *h, const void **ret) {
int r;
assert(h);
assert(ret);
r = retrieve_digest(h);
if (r < 0)
return r;
*ret = h->digest;
return 0;
}
int khash_digest_string(khash *h, char **ret) {
int r;
char *p;
assert(h);
assert(ret);
r = retrieve_digest(h);
if (r < 0)
return r;
p = hexmem(h->digest, h->digest_size);
if (!p)
return -ENOMEM;
*ret = p;
return 0;
}
src/basic/khash.h
-37
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@@ -1,37 +0,0 @@
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#pragma once
#include <inttypes.h>
#include <sys/types.h>
#include <sys/uio.h>
#include "macro.h"
typedef struct khash khash;
int khash_supported(void);
/* For plain hash functions. Hash functions commonly supported on today's kernels are: crc32c, crct10dif, crc32,
* sha224, sha256, sha512, sha384, sha1, md5, md4, sha3-224, sha3-256, sha3-384, sha3-512, and more. */
int khash_new(khash **ret, const char *algorithm);
/* For keyed hash functions. Hash functions commonly supported on today's kernels are: hmac(sha256), cmac(aes),
* cmac(des3_ede), hmac(sha3-512), hmac(sha3-384), hmac(sha3-256), hmac(sha3-224), hmac(rmd160), hmac(rmd128),
* hmac(sha224), hmac(sha512), hmac(sha384), hmac(sha1), hmac(md5), and more. */
int khash_new_with_key(khash **ret, const char *algorithm, const void *key, size_t key_size);
int khash_dup(khash *h, khash **ret);
khash* khash_unref(khash *h);
const char *khash_get_algorithm(khash *h);
size_t khash_get_size(khash *h);
int khash_reset(khash *h);
int khash_put(khash *h, const void *buffer, size_t size);
int khash_put_iovec(khash *h, const struct iovec *iovec, size_t n);
int khash_digest_data(khash *h, const void **ret);
int khash_digest_string(khash *h, char **ret);
DEFINE_TRIVIAL_CLEANUP_FUNC(khash*, khash_unref);
src/basic/meson.build
+2 -2
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@@ -72,6 +72,8 @@ basic_sources = files('''
hashmap.h
hexdecoct.c
hexdecoct.h
hmac.c
hmac.h
hostname-util.c
hostname-util.h
in-addr-util.c
@@ -80,8 +82,6 @@ basic_sources = files('''
inotify-util.h
io-util.c
io-util.h
khash.c
khash.h
limits-util.c
limits-util.h
linux/btrfs.h