From d07b00b7f31d0cb6675b4bdba269ce7f087ddd24 Mon Sep 17 00:00:00 2001 From: Michael J Gruber Date: Mon, 23 Jun 2014 09:05:49 +0200 Subject: [PATCH] verify-commit: scriptable commit signature verification Commit signatures can be verified using "git show -s --show-signature" or the "%G?" pretty format and parsing the output, which is well suited for user inspection, but not for scripting. Provide a command "verify-commit" which is analogous to "verify-tag": It returns 0 for good signatures and non-zero otherwise, has the gpg output on stderr and (optionally) the commit object on stdout, sans the signature, just like "verify-tag" does. Signed-off-by: Michael J Gruber Signed-off-by: Junio C Hamano --- Documentation/git-verify-commit.txt | 28 +++++++++ Makefile | 1 + builtin.h | 1 + builtin/verify-commit.c | 93 +++++++++++++++++++++++++++++ command-list.txt | 1 + git.c | 1 + 6 files changed, 125 insertions(+) create mode 100644 Documentation/git-verify-commit.txt create mode 100644 builtin/verify-commit.c diff --git a/Documentation/git-verify-commit.txt b/Documentation/git-verify-commit.txt new file mode 100644 index 0000000000..9413e2802a --- /dev/null +++ b/Documentation/git-verify-commit.txt @@ -0,0 +1,28 @@ +git-verify-commit(1) +==================== + +NAME +---- +git-verify-commit - Check the GPG signature of commits + +SYNOPSIS +-------- +[verse] +'git verify-commit' ... + +DESCRIPTION +----------- +Validates the gpg signature created by 'git commit -S'. + +OPTIONS +------- +-v:: +--verbose:: + Print the contents of the commit object before validating it. + +...:: + SHA-1 identifiers of Git commit objects. + +GIT +--- +Part of the linkgit:git[1] suite diff --git a/Makefile b/Makefile index 07ea105837..b92418de7b 100644 --- a/Makefile +++ b/Makefile @@ -999,6 +999,7 @@ BUILTIN_OBJS += builtin/update-ref.o BUILTIN_OBJS += builtin/update-server-info.o BUILTIN_OBJS += builtin/upload-archive.o BUILTIN_OBJS += builtin/var.o +BUILTIN_OBJS += builtin/verify-commit.o BUILTIN_OBJS += builtin/verify-pack.o BUILTIN_OBJS += builtin/verify-tag.o BUILTIN_OBJS += builtin/write-tree.o diff --git a/builtin.h b/builtin.h index c47c110e0f..5d91f31ca2 100644 --- a/builtin.h +++ b/builtin.h @@ -128,6 +128,7 @@ extern int cmd_update_server_info(int argc, const char **argv, const char *prefi extern int cmd_upload_archive(int argc, const char **argv, const char *prefix); extern int cmd_upload_archive_writer(int argc, const char **argv, const char *prefix); extern int cmd_var(int argc, const char **argv, const char *prefix); +extern int cmd_verify_commit(int argc, const char **argv, const char *prefix); extern int cmd_verify_tag(int argc, const char **argv, const char *prefix); extern int cmd_version(int argc, const char **argv, const char *prefix); extern int cmd_whatchanged(int argc, const char **argv, const char *prefix); diff --git a/builtin/verify-commit.c b/builtin/verify-commit.c new file mode 100644 index 0000000000..b0f85042b2 --- /dev/null +++ b/builtin/verify-commit.c @@ -0,0 +1,93 @@ +/* + * Builtin "git commit-commit" + * + * Copyright (c) 2014 Michael J Gruber + * + * Based on git-verify-tag + */ +#include "cache.h" +#include "builtin.h" +#include "commit.h" +#include "run-command.h" +#include +#include "parse-options.h" +#include "gpg-interface.h" + +static const char * const verify_commit_usage[] = { + N_("git verify-commit [-v|--verbose] ..."), + NULL +}; + +static int run_gpg_verify(const unsigned char *sha1, const char *buf, unsigned long size, int verbose) +{ + struct signature_check signature_check; + + memset(&signature_check, 0, sizeof(signature_check)); + + check_commit_signature(lookup_commit(sha1), &signature_check); + + if (verbose && signature_check.payload) + fputs(signature_check.payload, stdout); + + if (signature_check.gpg_output) + fputs(signature_check.gpg_output, stderr); + + signature_check_clear(&signature_check); + return signature_check.result != 'G'; +} + +static int verify_commit(const char *name, int verbose) +{ + enum object_type type; + unsigned char sha1[20]; + char *buf; + unsigned long size; + int ret; + + if (get_sha1(name, sha1)) + return error("commit '%s' not found.", name); + + buf = read_sha1_file(sha1, &type, &size); + if (!buf) + return error("%s: unable to read file.", name); + if (type != OBJ_COMMIT) + return error("%s: cannot verify a non-commit object of type %s.", + name, typename(type)); + + ret = run_gpg_verify(sha1, buf, size, verbose); + + free(buf); + return ret; +} + +static int git_verify_commit_config(const char *var, const char *value, void *cb) +{ + int status = git_gpg_config(var, value, cb); + if (status) + return status; + return git_default_config(var, value, cb); +} + +int cmd_verify_commit(int argc, const char **argv, const char *prefix) +{ + int i = 1, verbose = 0, had_error = 0; + const struct option verify_commit_options[] = { + OPT__VERBOSE(&verbose, N_("print commit contents")), + OPT_END() + }; + + git_config(git_verify_commit_config, NULL); + + argc = parse_options(argc, argv, prefix, verify_commit_options, + verify_commit_usage, PARSE_OPT_KEEP_ARGV0); + if (argc <= i) + usage_with_options(verify_commit_usage, verify_commit_options); + + /* sometimes the program was terminated because this signal + * was received in the process of writing the gpg input: */ + signal(SIGPIPE, SIG_IGN); + while (i < argc) + if (verify_commit(argv[i++], verbose)) + had_error = 1; + return had_error; +} diff --git a/command-list.txt b/command-list.txt index cf36c3d71e..a3ff0c9e60 100644 --- a/command-list.txt +++ b/command-list.txt @@ -132,6 +132,7 @@ git-update-server-info synchingrepositories git-upload-archive synchelpers git-upload-pack synchelpers git-var plumbinginterrogators +git-verify-commit ancillaryinterrogators git-verify-pack plumbinginterrogators git-verify-tag ancillaryinterrogators gitweb ancillaryinterrogators diff --git a/git.c b/git.c index 7780572948..bbc329395b 100644 --- a/git.c +++ b/git.c @@ -441,6 +441,7 @@ static struct cmd_struct commands[] = { { "upload-archive", cmd_upload_archive }, { "upload-archive--writer", cmd_upload_archive_writer }, { "var", cmd_var, RUN_SETUP_GENTLY }, + { "verify-commit", cmd_verify_commit, RUN_SETUP }, { "verify-pack", cmd_verify_pack }, { "verify-tag", cmd_verify_tag, RUN_SETUP }, { "version", cmd_version }, -- 2.47.1