From ec4afb4606e2b1ea44b0f32778a51c2a8be7eadd Mon Sep 17 00:00:00 2001 From: Luca Boccassi Date: Thu, 30 Sep 2021 11:01:45 +0100 Subject: [PATCH] libsystemd/sd-id128: use only internal hmac, remove khash/OpenSSL support Using OpenSSL brings in an additional dependency for all users of libsystemd.so even though it's just one API that makes use of it. The khash implementation is awkward as it requires context switches and computation inside the kernel, thus leaving the process. Remove both from libsystemd.so, and use exclusively the internal hmac fallback. While this is not optimized, the sd-id128 API is not used in performance-critical contexts where hardware acceleration would make a noticeable difference. --- LICENSES/README.md | 5 ++++ src/libsystemd/meson.build | 3 +-- src/libsystemd/sd-id128/sd-id128.c | 43 +++--------------------------- src/test/test-id128.c | 15 ++++------- 4 files changed, 15 insertions(+), 51 deletions(-) diff --git a/LICENSES/README.md b/LICENSES/README.md index f01049c13f..3c28de51b1 100644 --- a/LICENSES/README.md +++ b/LICENSES/README.md @@ -58,3 +58,8 @@ The following exceptions apply: **BSD-3-Clause** license. * any files under test/ without an explicit license we assume non-copyrightable (eg: computer-generated fuzzer data) + +## OpenSSL Notes + +Note that building the systemd project with OpenSSL does not affect the libsystemd.so +shared library, which is not linked with the OpenSSL library. diff --git a/src/libsystemd/meson.build b/src/libsystemd/meson.build index 8ec871f6a4..02b2cd64b2 100644 --- a/src/libsystemd/meson.build +++ b/src/libsystemd/meson.build @@ -170,8 +170,7 @@ libsystemd_static = static_library( include_directories : libsystemd_includes, link_with : libbasic, dependencies : [threads, - librt, - libopenssl], + librt], c_args : libsystemd_c_args) libsystemd_sym = files('libsystemd.sym') diff --git a/src/libsystemd/sd-id128/sd-id128.c b/src/libsystemd/sd-id128/sd-id128.c index 28ae10a198..992b19130e 100644 --- a/src/libsystemd/sd-id128/sd-id128.c +++ b/src/libsystemd/sd-id128/sd-id128.c @@ -4,21 +4,14 @@ #include #include -#if HAVE_OPENSSL -#include -#include -#endif - #include "sd-id128.h" #include "alloc-util.h" #include "fd-util.h" #include "hexdecoct.h" +#include "hmac.h" #include "id128-util.h" #include "io-util.h" -#if !HAVE_OPENSSL -#include "khash.h" -#endif #include "macro.h" #include "missing_syscall.h" #include "random-util.h" @@ -278,43 +271,15 @@ _public_ int sd_id128_randomize(sd_id128_t *ret) { } static int get_app_specific(sd_id128_t base, sd_id128_t app_id, sd_id128_t *ret) { + uint8_t hmac[SHA256_DIGEST_SIZE]; sd_id128_t result; assert(ret); -#if HAVE_OPENSSL - /* We prefer doing this in-process, since we this means we are not dependent on kernel configuration, - * and this also works in locked down container environments. But some distros don't like OpenSSL's - * license and its (in-) compatibility with GPL2, hence also support khash */ - uint8_t md[256/8]; - if (!HMAC(EVP_sha256(), - &base, sizeof(base), - (const unsigned char*) &app_id, sizeof(app_id), - md, NULL)) - return -ENOTRECOVERABLE; + hmac_sha256(&base, sizeof(base), &app_id, sizeof(app_id), hmac); /* Take only the first half. */ - memcpy(&result, md, MIN(sizeof(md), sizeof(result))); -#else - _cleanup_(khash_unrefp) khash *h = NULL; - const void *p; - int r; - - r = khash_new_with_key(&h, "hmac(sha256)", &base, sizeof(base)); - 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))); -#endif + memcpy(&result, hmac, MIN(sizeof(hmac), sizeof(result))); *ret = id128_make_v4_uuid(result); return 0; diff --git a/src/test/test-id128.c b/src/test/test-id128.c index a61b35b9a3..55fdab0ab8 100644 --- a/src/test/test-id128.c +++ b/src/test/test-id128.c @@ -146,16 +146,11 @@ int main(int argc, char *argv[]) { assert_se(id128_read_fd(fd, ID128_UUID, &id2) >= 0); assert_se(sd_id128_equal(id, id2)); - r = 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); - if (r == -EOPNOTSUPP) - log_info("khash not supported on this kernel, skipping sd_id128_get_machine_app_specific() checks"); - else { - assert_se(r >= 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)); - } + 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)); /* Query the invocation ID */ r = sd_id128_get_invocation(&id);