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 <git@drmicha.warpmail.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Michael J Gruber committed
Jun 23, 2014 at 09:05 UTC
d07b00b7f31d0cb6675b4bdba269ce7f087ddd24
6 files changed
+125
Documentation/git-verify-commit.txt
new
+28
@@ -0,0 +1,28 @@
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+git-verify-commit(1)
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+====================
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+
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+NAME
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+----
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+git-verify-commit - Check the GPG signature of commits
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+
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+SYNOPSIS
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+--------
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+[verse]
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+'git verify-commit' <commit>...
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+
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+DESCRIPTION
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+-----------
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+Validates the gpg signature created by 'git commit -S'.
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+
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+OPTIONS
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+-------
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+-v::
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+--verbose::
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+ Print the contents of the commit object before validating it.
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+
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+<commit>...::
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+ SHA-1 identifiers of Git commit objects.
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+
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+GIT
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+---
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+Part of the linkgit:git[1] suite
Makefile
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@@ -999,6 +999,7 @@ BUILTIN_OBJS += builtin/update-ref.o
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BUILTIN_OBJS += builtin/update-server-info.o
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BUILTIN_OBJS += builtin/upload-archive.o
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BUILTIN_OBJS += builtin/var.o
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+BUILTIN_OBJS += builtin/verify-commit.o
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BUILTIN_OBJS += builtin/verify-pack.o
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BUILTIN_OBJS += builtin/verify-tag.o
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BUILTIN_OBJS += builtin/write-tree.o
builtin.h
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@@ -128,6 +128,7 @@ extern int cmd_update_server_info(int argc, const char **argv, const char *prefi
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extern int cmd_upload_archive(int argc, const char **argv, const char *prefix);
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extern int cmd_upload_archive_writer(int argc, const char **argv, const char *prefix);
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extern int cmd_var(int argc, const char **argv, const char *prefix);
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+extern int cmd_verify_commit(int argc, const char **argv, const char *prefix);
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extern int cmd_verify_tag(int argc, const char **argv, const char *prefix);
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extern int cmd_version(int argc, const char **argv, const char *prefix);
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extern int cmd_whatchanged(int argc, const char **argv, const char *prefix);
builtin/verify-commit.c
new
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@@ -0,0 +1,93 @@
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+/*
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+ * Builtin "git commit-commit"
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+ *
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+ * Copyright (c) 2014 Michael J Gruber <git@drmicha.warpmail.net>
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+ *
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+ * Based on git-verify-tag
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+ */
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+#include "cache.h"
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+#include "builtin.h"
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+#include "commit.h"
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+#include "run-command.h"
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+#include <signal.h>
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+#include "parse-options.h"
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+#include "gpg-interface.h"
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+
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+static const char * const verify_commit_usage[] = {
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+ N_("git verify-commit [-v|--verbose] <commit>..."),
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+ NULL
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+};
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+
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+static int run_gpg_verify(const unsigned char *sha1, const char *buf, unsigned long size, int verbose)
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+{
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+ struct signature_check signature_check;
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+
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+ memset(&signature_check, 0, sizeof(signature_check));
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+
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+ check_commit_signature(lookup_commit(sha1), &signature_check);
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+
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+ if (verbose && signature_check.payload)
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+ fputs(signature_check.payload, stdout);
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+
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+ if (signature_check.gpg_output)
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+ fputs(signature_check.gpg_output, stderr);
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+
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+ signature_check_clear(&signature_check);
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+ return signature_check.result != 'G';
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+}
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+
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+static int verify_commit(const char *name, int verbose)
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+{
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+ enum object_type type;
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+ unsigned char sha1[20];
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+ char *buf;
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+ unsigned long size;
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+ int ret;
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+
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+ if (get_sha1(name, sha1))
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+ return error("commit '%s' not found.", name);
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+
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+ buf = read_sha1_file(sha1, &type, &size);
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+ if (!buf)
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+ return error("%s: unable to read file.", name);
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+ if (type != OBJ_COMMIT)
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+ return error("%s: cannot verify a non-commit object of type %s.",
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+ name, typename(type));
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+
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+ ret = run_gpg_verify(sha1, buf, size, verbose);
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+
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+ free(buf);
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+ return ret;
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+}
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+
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+static int git_verify_commit_config(const char *var, const char *value, void *cb)
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+{
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+ int status = git_gpg_config(var, value, cb);
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+ if (status)
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+ return status;
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+ return git_default_config(var, value, cb);
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+}
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+
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+int cmd_verify_commit(int argc, const char **argv, const char *prefix)
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+{
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+ int i = 1, verbose = 0, had_error = 0;
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+ const struct option verify_commit_options[] = {
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+ OPT__VERBOSE(&verbose, N_("print commit contents")),
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+ OPT_END()
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+ };
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+
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+ git_config(git_verify_commit_config, NULL);
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+
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+ argc = parse_options(argc, argv, prefix, verify_commit_options,
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+ verify_commit_usage, PARSE_OPT_KEEP_ARGV0);
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+ if (argc <= i)
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+ usage_with_options(verify_commit_usage, verify_commit_options);
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+
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+ /* sometimes the program was terminated because this signal
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+ * was received in the process of writing the gpg input: */
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+ signal(SIGPIPE, SIG_IGN);
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+ while (i < argc)
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+ if (verify_commit(argv[i++], verbose))
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+ had_error = 1;
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+ return had_error;
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+}
command-list.txt
+1
@@ -132,6 +132,7 @@ git-update-server-info synchingrepositories
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git-upload-archive synchelpers
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git-upload-pack synchelpers
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git-var plumbinginterrogators
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+git-verify-commit ancillaryinterrogators
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git-verify-pack plumbinginterrogators
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git-verify-tag ancillaryinterrogators
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gitweb ancillaryinterrogators
git.c
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@@ -441,6 +441,7 @@ static struct cmd_struct commands[] = {
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{ "upload-archive", cmd_upload_archive },
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{ "upload-archive--writer", cmd_upload_archive_writer },
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{ "var", cmd_var, RUN_SETUP_GENTLY },
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+ { "verify-commit", cmd_verify_commit, RUN_SETUP },
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{ "verify-pack", cmd_verify_pack },
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{ "verify-tag", cmd_verify_tag, RUN_SETUP },
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{ "version", cmd_version },