src/basic/khash.c - systemd-stable - Rivoreo Source Code Repositories

 /* SPDX-License-Identifier: LGPL-2.1+ */
 /***
   This file is part of systemd.

   Copyright 2016 Lennart Poettering

   systemd is free software; you can redistribute it and/or modify it
   under the terms of the GNU Lesser General Public License as published by
   the Free Software Foundation; either version 2.1 of the License, or
   (at your option) any later version.

   systemd is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/

 #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.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 = h;
         h = NULL;

         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 = copy;
         copy = NULL;

         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 = {
                 mh.msg_iov = (struct iovec*) iovec,
                 mh.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;
 }
	/* SPDX-License-Identifier: LGPL-2.1+ */
	/***
	This file is part of systemd.

	Copyright 2016 Lennart Poettering

	systemd is free software; you can redistribute it and/or modify it
	under the terms of the GNU Lesser General Public License as published by
	the Free Software Foundation; either version 2.1 of the License, or
	(at your option) any later version.

	systemd is distributed in the hope that it will be useful, but
	WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	Lesser General Public License for more details.

	You should have received a copy of the GNU Lesser General Public License
	along with systemd; If not, see <http://www.gnu.org/licenses/>.
	***/

	#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.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 = h;
	h = NULL;

	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 = copy;
	copy = NULL;

	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 = {
	mh.msg_iov = (struct iovec*) iovec,
	mh.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;
	}