diff --git a/.gitignore b/.gitignore index 21fcf9841c..2e39f65e43 100644 --- a/.gitignore +++ b/.gitignore @@ -198,6 +198,7 @@ /test-fs-util /test-fstab-util /test-glob-util +/test-hash /test-hashmap /test-hexdecoct /test-hostname diff --git a/Makefile-man.am b/Makefile-man.am index 013e0d7967..228e29fc4f 100644 --- a/Makefile-man.am +++ b/Makefile-man.am @@ -397,6 +397,7 @@ MANPAGES_ALIAS += \ man/sd_id128_from_string.3 \ man/sd_id128_get_boot.3 \ man/sd_id128_get_invocation.3 \ + man/sd_id128_get_machine_app_specific.3 \ man/sd_id128_is_null.3 \ man/sd_id128_t.3 \ man/sd_is_mq.3 \ @@ -750,6 +751,7 @@ man/sd_id128_equal.3: man/sd-id128.3 man/sd_id128_from_string.3: man/sd_id128_to_string.3 man/sd_id128_get_boot.3: man/sd_id128_get_machine.3 man/sd_id128_get_invocation.3: man/sd_id128_get_machine.3 +man/sd_id128_get_machine_app_specific.3: man/sd_id128_get_machine.3 man/sd_id128_is_null.3: man/sd-id128.3 man/sd_id128_t.3: man/sd-id128.3 man/sd_is_mq.3: man/sd_is_fifo.3 @@ -1531,6 +1533,9 @@ man/sd_id128_get_boot.html: man/sd_id128_get_machine.html man/sd_id128_get_invocation.html: man/sd_id128_get_machine.html $(html-alias) +man/sd_id128_get_machine_app_specific.html: man/sd_id128_get_machine.html + $(html-alias) + man/sd_id128_is_null.html: man/sd-id128.html $(html-alias) diff --git a/Makefile.am b/Makefile.am index 124e1867cd..99adfe4480 100644 --- a/Makefile.am +++ b/Makefile.am @@ -938,7 +938,9 @@ libbasic_la_SOURCES = \ src/basic/alloc-util.h \ src/basic/alloc-util.c \ src/basic/format-util.h \ - src/basic/nss-util.h + src/basic/nss-util.h \ + src/basic/khash.h \ + src/basic/khash.c nodist_libbasic_la_SOURCES = \ src/basic/errno-from-name.h \ @@ -4045,6 +4047,16 @@ test_id128_LDADD = \ tests += \ test-id128 +# ------------------------------------------------------------------------------ +test_hash_SOURCES = \ + src/test/test-hash.c + +test_hash_LDADD = \ + libsystemd-shared.la + +tests += \ + test-hash + # ------------------------------------------------------------------------------ bin_PROGRAMS += \ diff --git a/man/machine-id.xml b/man/machine-id.xml index a722649de4..3c261bffcc 100644 --- a/man/machine-id.xml +++ b/man/machine-id.xml @@ -71,13 +71,14 @@ This machine ID adheres to the same format and logic as the D-Bus machine ID. - This ID uniquely identifies the host. It should be considered "confidential", and must not - be exposed in untrusted environments, in particular on the network. If a stable unique - identifier that is tied to the machine is needed for some application, the machine ID or any - part of it must not be used directly. Instead the machine ID should be hashed with a - cryptographic, keyed hash function, using a fixed, application-specific key. That way the ID - will be properly unique, and derived in a constant way from the machine ID but there will be no - way to retrieve the original machine ID from the application-specific one. + This ID uniquely identifies the host. It should be considered "confidential", and must not be exposed in + untrusted environments, in particular on the network. If a stable unique identifier that is tied to the machine is + needed for some application, the machine ID or any part of it must not be used directly. Instead the machine ID + should be hashed with a cryptographic, keyed hash function, using a fixed, application-specific key. That way the + ID will be properly unique, and derived in a constant way from the machine ID but there will be no way to retrieve + the original machine ID from the application-specific one. The + sd_id128_get_machine_app_specific3 + API provides an implementation of such an algorithm. The systemd-machine-id-setup1 diff --git a/man/sd_id128_get_machine.xml b/man/sd_id128_get_machine.xml index 9a86c24aed..3938c6d836 100644 --- a/man/sd_id128_get_machine.xml +++ b/man/sd_id128_get_machine.xml @@ -44,6 +44,7 @@ sd_id128_get_machine + sd_id128_get_machine_app_specific sd_id128_get_boot sd_id128_get_invocation Retrieve 128-bit IDs @@ -58,6 +59,12 @@ sd_id128_t *ret + + int sd_id128_get_machine_app_specific + sd_id128_t app_id + sd_id128_t *ret + + int sd_id128_get_boot sd_id128_t *ret @@ -74,11 +81,22 @@ Description - sd_id128_get_machine() returns the - machine ID of the executing host. This reads and parses the - machine-id5 - file. This function caches the machine ID internally to make - retrieving the machine ID a cheap operation. + sd_id128_get_machine() returns the machine ID of the executing host. This reads and + parses the machine-id5 + file. This function caches the machine ID internally to make retrieving the machine ID a cheap operation. This ID + may be used wherever a unique identifier for the local system is needed. However, it is recommended to use this ID + as-is only in trusted environments. In untrusted environments it is recommended to derive an application specific + ID from this machine ID, in an irreversable (cryptographically secure) way. To make this easy + sd_id128_get_machine_app_specific() is provided, see below. + + sd_id128_get_machine_app_specific() is similar to + sd_id128_get_machine(), but retrieves a machine ID that is specific to the application that is + identified by the indicated application ID. It is recommended to use this function instead of + sd_id128_get_machine() when passing an ID to untrusted environments, in order to make sure + that the original machine ID may not be determined externally. The application-specific ID should be generated via + a tool like journalctl --new-id128, and may be compiled into the application. This function will + return the same application-specific ID for each combination of machine ID and application ID. Internally, this + function calculates HMAC-SHA256 of the application ID, keyed by the machine ID. sd_id128_get_boot() returns the boot ID of the executing kernel. This reads and parses the @@ -95,10 +113,10 @@ systemd.exec5 for details. The ID is cached internally. In future a different mechanism to determine the invocation ID may be added. - Note that sd_id128_get_boot() and sd_id128_get_invocation() always - return UUID v4 compatible IDs. sd_id128_get_machine() will also return a UUID v4-compatible - ID on new installations but might not on older. It is possible to convert the machine ID into a UUID v4-compatible - one. For more information, see + Note that sd_id128_get_machine_app_specific(), sd_id128_get_boot() + and sd_id128_get_invocation() always return UUID v4 compatible IDs. + sd_id128_get_machine() will also return a UUID v4-compatible ID on new installations but might + not on older. It is possible to convert the machine ID into a UUID v4-compatible one. For more information, see machine-id5. For more information about the sd_id128_t @@ -117,12 +135,35 @@ Notes - The sd_id128_get_machine(), sd_id128_get_boot() and - sd_id128_get_invocation() interfaces are available as a shared library, which can be compiled - and linked to with the libsystemd The sd_id128_get_machine(), sd_id128_get_machine_app_specific() + sd_id128_get_boot() and sd_id128_get_invocation() interfaces are + available as a shared library, which can be compiled and linked to with the + libsystemd pkg-config1 file. + + Examples + + + Application-specific machine ID + + Here's a simple example for an application specific machine ID: + + #include <systemd/sd-id128.h> +#include <stdio.h> + +#define OUR_APPLICATION_ID SD_ID128_MAKE(c2,73,27,73,23,db,45,4e,a6,3b,b9,6e,79,b5,3e,97) + +int main(int argc, char *argv[]) { + sd_id128_t id; + sd_id128_get_machine_app_specific(OUR_APPLICATION_ID, &id); + printf("Our application ID: " SD_ID128_FORMAT_STR "\n", SD_ID128_FORMAT_VAL(id)); + return 0; +} + + + See Also diff --git a/src/basic/khash.c b/src/basic/khash.c new file mode 100644 index 0000000000..9a2a3edb75 --- /dev/null +++ b/src/basic/khash.c @@ -0,0 +1,275 @@ +/*** + 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 . +***/ + +#include +#include +#include + +#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_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; + 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; + + 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); + free(h); + + return NULL; +} + +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) + 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; +} diff --git a/src/basic/khash.h b/src/basic/khash.h new file mode 100644 index 0000000000..f404a68236 --- /dev/null +++ b/src/basic/khash.h @@ -0,0 +1,53 @@ +#pragma once + +/*** + 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 . +***/ + +#include +#include +#include + +#include "macro.h" + +typedef struct khash khash; + +/* 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); diff --git a/src/basic/missing.h b/src/basic/missing.h index 8833617dc6..1502b3f4f4 100644 --- a/src/basic/missing.h +++ b/src/basic/missing.h @@ -1109,4 +1109,8 @@ struct ethtool_link_settings { #endif +#ifndef SOL_ALG +#define SOL_ALG 279 +#endif + #include "missing_syscall.h" diff --git a/src/libsystemd/libsystemd.sym b/src/libsystemd/libsystemd.sym index d48ef6bbe2..46c4dac7d7 100644 --- a/src/libsystemd/libsystemd.sym +++ b/src/libsystemd/libsystemd.sym @@ -511,3 +511,8 @@ global: sd_bus_get_exit_on_disconnect; sd_id128_get_invocation; } LIBSYSTEMD_231; + +LIBSYSTEMD_233 { +global: + sd_id128_get_machine_app_specific; +} LIBSYSTEMD_232; diff --git a/src/libsystemd/sd-id128/sd-id128.c b/src/libsystemd/sd-id128/sd-id128.c index d4450c70a0..0d673ba655 100644 --- a/src/libsystemd/sd-id128/sd-id128.c +++ b/src/libsystemd/sd-id128/sd-id128.c @@ -27,6 +27,7 @@ #include "hexdecoct.h" #include "id128-util.h" #include "io-util.h" +#include "khash.h" #include "macro.h" #include "random-util.h" #include "util.h" @@ -181,3 +182,34 @@ _public_ int sd_id128_randomize(sd_id128_t *ret) { *ret = make_v4_uuid(t); return 0; } + +_public_ int sd_id128_get_machine_app_specific(sd_id128_t app_id, sd_id128_t *ret) { + _cleanup_(khash_unrefp) khash *h = NULL; + sd_id128_t m, result; + const void *p; + int r; + + assert_return(ret, -EINVAL); + + r = sd_id128_get_machine(&m); + if (r < 0) + return r; + + r = khash_new_with_key(&h, "hmac(sha256)", &m, sizeof(m)); + if (r < 0) + return r; + + r = khash_put(h, &app_id, sizeof(app_id)); + if (r < 0) + return r; + + r = khash_digest_data(h, &p); + if (r < 0) + return r; + + /* We chop off the trailing 16 bytes */ + memcpy(&result, p, MIN(khash_get_size(h), sizeof(result))); + + *ret = make_v4_uuid(result); + return 0; +} diff --git a/src/systemd/sd-id128.h b/src/systemd/sd-id128.h index ee011b1861..6cc8e4ac0e 100644 --- a/src/systemd/sd-id128.h +++ b/src/systemd/sd-id128.h @@ -39,12 +39,12 @@ union sd_id128 { #define SD_ID128_STRING_MAX 33 char *sd_id128_to_string(sd_id128_t id, char s[SD_ID128_STRING_MAX]); - int sd_id128_from_string(const char *s, sd_id128_t *ret); int sd_id128_randomize(sd_id128_t *ret); int sd_id128_get_machine(sd_id128_t *ret); +int sd_id128_get_machine_app_specific(sd_id128_t app_id, sd_id128_t *ret); int sd_id128_get_boot(sd_id128_t *ret); int sd_id128_get_invocation(sd_id128_t *ret); diff --git a/src/test/test-hash.c b/src/test/test-hash.c new file mode 100644 index 0000000000..1972b94cfe --- /dev/null +++ b/src/test/test-hash.c @@ -0,0 +1,82 @@ +/*** + 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 . +***/ + +#include "alloc-util.h" +#include "log.h" +#include "string-util.h" +#include "khash.h" + +int main(int argc, char *argv[]) { + _cleanup_(khash_unrefp) khash *h = NULL, *copy = NULL; + _cleanup_free_ char *s = NULL; + + log_set_max_level(LOG_DEBUG); + + assert_se(khash_new(&h, NULL) == -EINVAL); + assert_se(khash_new(&h, "") == -EINVAL); + assert_se(khash_new(&h, "foobar") == -EOPNOTSUPP); + + assert_se(khash_new(&h, "sha256") >= 0); + assert_se(khash_get_size(h) == 32); + assert_se(streq(khash_get_algorithm(h), "sha256")); + + assert_se(khash_digest_string(h, &s) >= 0); + assert_se(streq(s, "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855")); + s = mfree(s); + + assert_se(khash_put(h, "foobar", 6) >= 0); + assert_se(khash_digest_string(h, &s) >= 0); + assert_se(streq(s, "c3ab8ff13720e8ad9047dd39466b3c8974e592c2fa383d4a3960714caef0c4f2")); + s = mfree(s); + + assert_se(khash_put(h, "piep", 4) >= 0); + assert_se(khash_digest_string(h, &s) >= 0); + assert_se(streq(s, "f114d872b5ea075d3be9040d0b7a429514b3f9324a8e8e3dc3fb24c34ee56bea")); + s = mfree(s); + + assert_se(khash_put(h, "foo", 3) >= 0); + assert_se(khash_dup(h, ©) >= 0); + + assert_se(khash_put(h, "bar", 3) >= 0); + assert_se(khash_put(copy, "bar", 3) >= 0); + + assert_se(khash_digest_string(h, &s) >= 0); + assert_se(streq(s, "c3ab8ff13720e8ad9047dd39466b3c8974e592c2fa383d4a3960714caef0c4f2")); + s = mfree(s); + + assert_se(khash_digest_string(copy, &s) >= 0); + assert_se(streq(s, "c3ab8ff13720e8ad9047dd39466b3c8974e592c2fa383d4a3960714caef0c4f2")); + s = mfree(s); + + h = khash_unref(h); + + assert_se(khash_new_with_key(&h, "hmac(sha256)", "quux", 4) >= 0); + assert_se(khash_get_size(h) == 32); + assert_se(streq(khash_get_algorithm(h), "hmac(sha256)")); + + assert_se(khash_digest_string(h, &s) >= 0); + assert_se(streq(s, "abed9f8218ab473f77218a6a7d39abf1d21fa46d0700c4898e330ba88309d5ae")); + s = mfree(s); + + assert_se(khash_put(h, "foobar", 6) >= 0); + assert_se(khash_digest_string(h, &s) >= 0); + assert_se(streq(s, "33f6c70a60db66007d5325d5d1dea37c371354e5b83347a59ad339ce9f4ba3dc")); + + return 0; +} diff --git a/src/test/test-id128.c b/src/test/test-id128.c index 1c8e5549da..ab5a111ba9 100644 --- a/src/test/test-id128.c +++ b/src/test/test-id128.c @@ -153,5 +153,11 @@ int main(int argc, char *argv[]) { assert_se(id128_read_fd(fd, ID128_UUID, &id2) >= 0); assert_se(sd_id128_equal(id, id2)); + assert_se(sd_id128_get_machine_app_specific(SD_ID128_MAKE(f0,3d,aa,eb,1c,33,4b,43,a7,32,17,29,44,bf,77,2e), &id) >= 0); + assert_se(sd_id128_get_machine_app_specific(SD_ID128_MAKE(f0,3d,aa,eb,1c,33,4b,43,a7,32,17,29,44,bf,77,2e), &id2) >= 0); + assert_se(sd_id128_equal(id, id2)); + assert_se(sd_id128_get_machine_app_specific(SD_ID128_MAKE(51,df,0b,4b,c3,b0,4c,97,80,e2,99,b9,8c,a3,73,b8), &id2) >= 0); + assert_se(!sd_id128_equal(id, id2)); + return 0; }