]> git.ipfire.org Git - thirdparty/git.git/commitdiff
fast-export, fast-import: add support for signed-commits
authorLuke Shumaker <lukeshu@datawire.io>
Mon, 10 Mar 2025 15:57:46 +0000 (16:57 +0100)
committerJunio C Hamano <gitster@pobox.com>
Mon, 10 Mar 2025 20:24:56 +0000 (13:24 -0700)
fast-export has a --signed-tags= option that controls how to handle tag
signatures.  However, there is no equivalent for commit signatures; it
just silently strips the signature out of the commit (analogously to
--signed-tags=strip).

While signatures are generally problematic for fast-export/fast-import
(because hashes are likely to change), if they're going to support tag
signatures, there's no reason to not also support commit signatures.

So, implement a --signed-commits= option that mirrors the --signed-tags=
option.

On the fast-export side, try to be as much like signed-tags as possible,
in both implementation and in user-interface.  This will change the
default behavior to '--signed-commits=abort' from what is now
'--signed-commits=strip'.  In order to provide an escape hatch for users
of third-party tools that call fast-export and do not yet know of the
--signed-commits= option, add an environment variable
'FAST_EXPORT_SIGNED_COMMITS_NOABORT=1' that changes the default to
'--signed-commits=warn-strip'.

Signed-off-by: Luke Shumaker <lukeshu@datawire.io>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Documentation/git-fast-export.adoc
Documentation/git-fast-import.adoc
builtin/fast-export.c
builtin/fast-import.c
t/t9350-fast-export.sh

index 2bb52261a0b9954604fc722bea6bcf9a2dac2e3a..413a5274969b6c3adab7562e46e5a080e92a799e 100644 (file)
@@ -44,6 +44,17 @@ affecting tags or any commit in their history will be performed by you
 or by fast-export or fast-import, or if you do not care that the
 resulting tag will have an invalid signature.
 
+--signed-commits=(verbatim|warn-verbatim|warn-strip|strip|abort)::
+       Specify how to handle signed commits.  Behaves exactly as
+       '--signed-tags', but for commits.  Default is 'abort'.
++
+Earlier versions this command that did not have '--signed-commits'
+behaved as if '--signed-commits=strip'.  As an escape hatch for users
+of tools that call 'git fast-export' but do not yet support
+'--signed-commits', you may set the environment variable
+'FAST_EXPORT_SIGNED_COMMITS_NOABORT=1' in order to change the default
+from 'abort' to 'warn-strip'.
+
 --tag-of-filtered-object=(abort|drop|rewrite)::
        Specify how to handle tags whose tagged object is filtered out.
        Since revisions and files to export can be limited by path,
index 8e0de618c0e4df696560352299bcbe767ec974aa..7b107f5e8e9da5779856eb620ac4ef73de521909 100644 (file)
@@ -431,12 +431,21 @@ and control the current import process.  More detailed discussion
 Create or update a branch with a new commit, recording one logical
 change to the project.
 
+////
+Yes, it's intentional that the 'gpgsig' line doesn't have a trailing
+`LF`; the definition of `data` has a byte-count prefix, so it
+doesn't need an `LF` to act as a terminator (and `data` also already
+includes an optional trailing `LF?` just in case you want to include
+one).
+////
+
 ....
        'commit' SP <ref> LF
        mark?
        original-oid?
        ('author' (SP <name>)? SP LT <email> GT SP <when> LF)?
        'committer' (SP <name>)? SP LT <email> GT SP <when> LF
+       ('gpgsig' SP <alg> LF data)?
        ('encoding' SP <encoding> LF)?
        data
        ('from' SP <commit-ish> LF)?
@@ -505,6 +514,15 @@ that was selected by the --date-format=<fmt> command-line option.
 See ``Date Formats'' above for the set of supported formats, and
 their syntax.
 
+`gpgsig`
+^^^^^^^^
+
+The optional `gpgsig` command is used to include a PGP/GPG signature
+that signs the commit data.
+
+Here <alg> specifies which hashing algorithm is used for this
+signature, either `sha1` or `sha256`.
+
 `encoding`
 ^^^^^^^^^^
 The optional `encoding` command indicates the encoding of the commit
index 39d43c2a292d434f8a2ba696151ccbc5c5811a05..126980f724fd69bb75cf70a0480c3b54d1b9b329 100644 (file)
@@ -35,8 +35,11 @@ static const char *fast_export_usage[] = {
        NULL
 };
 
+enum sign_mode { SIGN_ABORT, SIGN_VERBATIM, SIGN_STRIP, SIGN_WARN_VERBATIM, SIGN_WARN_STRIP };
+
 static int progress;
-static enum signed_tag_mode { SIGNED_TAG_ABORT, VERBATIM, WARN_VERBATIM, WARN_STRIP, STRIP } signed_tag_mode = SIGNED_TAG_ABORT;
+static enum sign_mode signed_tag_mode = SIGN_ABORT;
+static enum sign_mode signed_commit_mode = SIGN_ABORT;
 static enum tag_of_filtered_mode { TAG_FILTERING_ABORT, DROP, REWRITE } tag_of_filtered_mode = TAG_FILTERING_ABORT;
 static enum reencode_mode { REENCODE_ABORT, REENCODE_YES, REENCODE_NO } reencode_mode = REENCODE_ABORT;
 static int fake_missing_tagger;
@@ -53,23 +56,24 @@ static int anonymize;
 static struct hashmap anonymized_seeds;
 static struct revision_sources revision_sources;
 
-static int parse_opt_signed_tag_mode(const struct option *opt,
+static int parse_opt_sign_mode(const struct option *opt,
                                     const char *arg, int unset)
 {
-       enum signed_tag_mode *val = opt->value;
-
-       if (unset || !strcmp(arg, "abort"))
-               *val = SIGNED_TAG_ABORT;
+       enum sign_mode *val = opt->value;
+       if (unset)
+               return 0;
+       else if (!strcmp(arg, "abort"))
+               *val = SIGN_ABORT;
        else if (!strcmp(arg, "verbatim") || !strcmp(arg, "ignore"))
-               *val = VERBATIM;
+               *val = SIGN_VERBATIM;
        else if (!strcmp(arg, "warn-verbatim") || !strcmp(arg, "warn"))
-               *val = WARN_VERBATIM;
+               *val = SIGN_WARN_VERBATIM;
        else if (!strcmp(arg, "warn-strip"))
-               *val = WARN_STRIP;
+               *val = SIGN_WARN_STRIP;
        else if (!strcmp(arg, "strip"))
-               *val = STRIP;
+               *val = SIGN_STRIP;
        else
-               return error("Unknown signed-tags mode: %s", arg);
+               return error("Unknown %s mode: %s", opt->long_name, arg);
        return 0;
 }
 
@@ -611,6 +615,43 @@ static void anonymize_ident_line(const char **beg, const char **end)
        *end = out->buf + out->len;
 }
 
+/*
+ * find_commit_multiline_header is similar to find_commit_header,
+ * except that it handles multi-line headers, rather than simply
+ * returning the first line of the header.
+ *
+ * The returned string has had the ' ' line continuation markers
+ * removed, and points to allocated memory that must be free()d (not
+ * to memory within 'msg').
+ *
+ * If the header is found, then *end is set to point at the '\n' in
+ * msg that immediately follows the header value.
+ */
+static const char *find_commit_multiline_header(const char *msg,
+                                               const char *key,
+                                               const char **end)
+{
+       struct strbuf val = STRBUF_INIT;
+       const char *bol, *eol;
+       size_t len;
+
+       bol = find_commit_header(msg, key, &len);
+       if (!bol)
+               return NULL;
+       eol = bol + len;
+       strbuf_add(&val, bol, len);
+
+       while (eol[0] == '\n' && eol[1] == ' ') {
+               bol = eol + 2;
+               eol = strchrnul(bol, '\n');
+               strbuf_addch(&val, '\n');
+               strbuf_add(&val, bol, eol - bol);
+       }
+
+       *end = eol;
+       return strbuf_detach(&val, NULL);
+}
+
 static void handle_commit(struct commit *commit, struct rev_info *rev,
                          struct string_list *paths_of_changed_objects)
 {
@@ -619,6 +660,7 @@ static void handle_commit(struct commit *commit, struct rev_info *rev,
        const char *author, *author_end, *committer, *committer_end;
        const char *encoding = NULL;
        size_t encoding_len;
+       const char *signature_alg = NULL, *signature = NULL;
        const char *message;
        char *reencoded = NULL;
        struct commit_list *p;
@@ -645,17 +687,25 @@ static void handle_commit(struct commit *commit, struct rev_info *rev,
        commit_buffer_cursor = committer_end = strchrnul(committer, '\n');
 
        /*
-        * find_commit_header() gets a `+ 1` because
-        * commit_buffer_cursor points at the trailing "\n" at the end
-        * of the previous line, but find_commit_header() wants a
+        * find_commit_header() and find_commit_multiline_header() get
+        * a `+ 1` because commit_buffer_cursor points at the trailing
+        * "\n" at the end of the previous line, but they want a
         * pointer to the beginning of the next line.
         */
+
        if (*commit_buffer_cursor == '\n') {
                encoding = find_commit_header(commit_buffer_cursor + 1, "encoding", &encoding_len);
                if (encoding)
                        commit_buffer_cursor = encoding + encoding_len;
        }
 
+       if (*commit_buffer_cursor == '\n') {
+               if ((signature = find_commit_multiline_header(commit_buffer_cursor + 1, "gpgsig", &commit_buffer_cursor)))
+                       signature_alg = "sha1";
+               else if ((signature = find_commit_multiline_header(commit_buffer_cursor + 1, "gpgsig-sha256", &commit_buffer_cursor)))
+                       signature_alg = "sha256";
+       }
+
        message = strstr(commit_buffer_cursor, "\n\n");
        if (message)
                message += 2;
@@ -719,6 +769,31 @@ static void handle_commit(struct commit *commit, struct rev_info *rev,
        printf("%.*s\n%.*s\n",
               (int)(author_end - author), author,
               (int)(committer_end - committer), committer);
+       if (signature) {
+               switch (signed_commit_mode) {
+               case SIGN_ABORT:
+                       die("encountered signed commit %s; use "
+                           "--signed-commits=<mode> to handle it",
+                           oid_to_hex(&commit->object.oid));
+               case SIGN_WARN_VERBATIM:
+                       warning("exporting signed commit %s",
+                               oid_to_hex(&commit->object.oid));
+                       /* fallthru */
+               case SIGN_VERBATIM:
+                       printf("gpgsig %s\ndata %u\n%s",
+                              signature_alg,
+                              (unsigned)strlen(signature),
+                              signature);
+                       break;
+               case SIGN_WARN_STRIP:
+                       warning("stripping signature from commit %s",
+                               oid_to_hex(&commit->object.oid));
+                       /* fallthru */
+               case SIGN_STRIP:
+                       break;
+               }
+               free((char *)signature);
+       }
        if (!reencoded && encoding)
                printf("encoding %.*s\n", (int)encoding_len, encoding);
        printf("data %u\n%s",
@@ -834,21 +909,21 @@ static void handle_tag(const char *name, struct tag *tag)
                                               "\n-----BEGIN PGP SIGNATURE-----\n");
                if (signature)
                        switch (signed_tag_mode) {
-                       case SIGNED_TAG_ABORT:
+                       case SIGN_ABORT:
                                die("encountered signed tag %s; use "
                                    "--signed-tags=<mode> to handle it",
                                    oid_to_hex(&tag->object.oid));
-                       case WARN_VERBATIM:
+                       case SIGN_WARN_VERBATIM:
                                warning("exporting signed tag %s",
                                        oid_to_hex(&tag->object.oid));
                                /* fallthru */
-                       case VERBATIM:
+                       case SIGN_VERBATIM:
                                break;
-                       case WARN_STRIP:
+                       case SIGN_WARN_STRIP:
                                warning("stripping signature from tag %s",
                                        oid_to_hex(&tag->object.oid));
                                /* fallthru */
-                       case STRIP:
+                       case SIGN_STRIP:
                                message_size = signature + 1 - message;
                                break;
                        }
@@ -1194,6 +1269,7 @@ int cmd_fast_export(int argc,
                    const char *prefix,
                    struct repository *repo UNUSED)
 {
+       const char *env_signed_commits_noabort;
        struct rev_info revs;
        struct commit *commit;
        char *export_filename = NULL,
@@ -1207,7 +1283,10 @@ int cmd_fast_export(int argc,
                            N_("show progress after <n> objects")),
                OPT_CALLBACK(0, "signed-tags", &signed_tag_mode, N_("mode"),
                             N_("select handling of signed tags"),
-                            parse_opt_signed_tag_mode),
+                            parse_opt_sign_mode),
+               OPT_CALLBACK(0, "signed-commits", &signed_commit_mode, N_("mode"),
+                            N_("select handling of signed commits"),
+                            parse_opt_sign_mode),
                OPT_CALLBACK(0, "tag-of-filtered-object", &tag_of_filtered_mode, N_("mode"),
                             N_("select handling of tags that tag filtered objects"),
                             parse_opt_tag_of_filtered_mode),
@@ -1248,6 +1327,10 @@ int cmd_fast_export(int argc,
        if (argc == 1)
                usage_with_options (fast_export_usage, options);
 
+       env_signed_commits_noabort = getenv("FAST_EXPORT_SIGNED_COMMITS_NOABORT");
+       if (env_signed_commits_noabort && *env_signed_commits_noabort)
+               signed_commit_mode = SIGN_WARN_STRIP;
+
        /* we handle encodings */
        git_config(git_default_config, NULL);
 
index d6a368a56652031e68511548486874fa305ee725..a5b33eb91ea2280a099bdd2af6c12ba05a2b0962 100644 (file)
@@ -2719,10 +2719,13 @@ static struct hash_list *parse_merge(unsigned int *count)
 
 static void parse_new_commit(const char *arg)
 {
+       static struct strbuf sig = STRBUF_INIT;
        static struct strbuf msg = STRBUF_INIT;
+       struct string_list siglines = STRING_LIST_INIT_NODUP;
        struct branch *b;
        char *author = NULL;
        char *committer = NULL;
+       char *sig_alg = NULL;
        char *encoding = NULL;
        struct hash_list *merge_list = NULL;
        unsigned int merge_count;
@@ -2746,6 +2749,13 @@ static void parse_new_commit(const char *arg)
        }
        if (!committer)
                die("Expected committer but didn't get one");
+       if (skip_prefix(command_buf.buf, "gpgsig ", &v)) {
+               sig_alg = xstrdup(v);
+               read_next_command();
+               parse_data(&sig, 0, NULL);
+               read_next_command();
+       } else
+               strbuf_setlen(&sig, 0);
        if (skip_prefix(command_buf.buf, "encoding ", &v)) {
                encoding = xstrdup(v);
                read_next_command();
@@ -2819,10 +2829,23 @@ static void parse_new_commit(const char *arg)
                strbuf_addf(&new_data,
                        "encoding %s\n",
                        encoding);
+       if (sig_alg) {
+               if (!strcmp(sig_alg, "sha1"))
+                       strbuf_addstr(&new_data, "gpgsig ");
+               else if (!strcmp(sig_alg, "sha256"))
+                       strbuf_addstr(&new_data, "gpgsig-sha256 ");
+               else
+                       die("Expected gpgsig algorithm sha1 or sha256, got %s", sig_alg);
+               string_list_split_in_place(&siglines, sig.buf, "\n", -1);
+               strbuf_add_separated_string_list(&new_data, "\n ", &siglines);
+               strbuf_addch(&new_data, '\n');
+       }
        strbuf_addch(&new_data, '\n');
        strbuf_addbuf(&new_data, &msg);
+       string_list_clear(&siglines, 1);
        free(author);
        free(committer);
+       free(sig_alg);
        free(encoding);
 
        if (!store_object(OBJ_COMMIT, &new_data, NULL, &b->oid, next_mark))
index cc110727fb1eddf9a337d1de9db3474032f424b3..304bac5b1dfb0d0b016799c328b4bd78707fa216 100755 (executable)
@@ -8,6 +8,7 @@ GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
 . ./test-lib.sh
+. "$TEST_DIRECTORY/lib-gpg.sh"
 
 test_expect_success 'setup' '
 
@@ -284,10 +285,107 @@ test_expect_success 'signed-tags=warn-strip' '
        test -s err
 '
 
+test_expect_success GPG 'set up signed commit' '
+
+       # Generate a commit with both "gpgsig" and "encoding" set, so
+       # that we can test that fast-import gets the ordering correct
+       # between the two.
+       test_config i18n.commitEncoding ISO-8859-1 &&
+       git checkout -f -b commit-signing main &&
+       echo Sign your name >file-sign &&
+       git add file-sign &&
+       git commit -S -m "signed commit" &&
+       COMMIT_SIGNING=$(git rev-parse --verify commit-signing)
+
+'
+
+test_expect_success GPG 'signed-commits default' '
+
+       sane_unset FAST_EXPORT_SIGNED_COMMITS_NOABORT &&
+       test_must_fail git fast-export --reencode=no commit-signing &&
+
+       FAST_EXPORT_SIGNED_COMMITS_NOABORT=1 git fast-export --reencode=no commit-signing >output 2>err &&
+       ! grep ^gpgsig output &&
+       grep "^encoding ISO-8859-1" output &&
+       test -s err &&
+       sed "s/commit-signing/commit-strip-signing/" output | (
+               cd new &&
+               git fast-import &&
+               STRIPPED=$(git rev-parse --verify refs/heads/commit-strip-signing) &&
+               test $COMMIT_SIGNING != $STRIPPED
+       )
+
+'
+
+test_expect_success GPG 'signed-commits=abort' '
+
+       test_must_fail git fast-export --signed-commits=abort commit-signing
+
+'
+
+test_expect_success GPG 'signed-commits=verbatim' '
+
+       git fast-export --signed-commits=verbatim --reencode=no commit-signing >output &&
+       grep "^gpgsig sha" output &&
+       grep "encoding ISO-8859-1" output &&
+       (
+               cd new &&
+               git fast-import &&
+               STRIPPED=$(git rev-parse --verify refs/heads/commit-signing) &&
+               test $COMMIT_SIGNING = $STRIPPED
+       ) <output
+
+'
+
+test_expect_success GPG 'signed-commits=warn-verbatim' '
+
+       git fast-export --signed-commits=warn-verbatim --reencode=no commit-signing >output 2>err &&
+       grep "^gpgsig sha" output &&
+       grep "encoding ISO-8859-1" output &&
+       test -s err &&
+       (
+               cd new &&
+               git fast-import &&
+               STRIPPED=$(git rev-parse --verify refs/heads/commit-signing) &&
+               test $COMMIT_SIGNING = $STRIPPED
+       ) <output
+
+'
+
+test_expect_success GPG 'signed-commits=strip' '
+
+       git fast-export --signed-commits=strip --reencode=no commit-signing >output &&
+       ! grep ^gpgsig output &&
+       grep "^encoding ISO-8859-1" output &&
+       sed "s/commit-signing/commit-strip-signing/" output | (
+               cd new &&
+               git fast-import &&
+               STRIPPED=$(git rev-parse --verify refs/heads/commit-strip-signing) &&
+               test $COMMIT_SIGNING != $STRIPPED
+       )
+
+'
+
+test_expect_success GPG 'signed-commits=warn-strip' '
+
+       git fast-export --signed-commits=warn-strip --reencode=no commit-signing >output 2>err &&
+       ! grep ^gpgsig output &&
+       grep "^encoding ISO-8859-1" output &&
+       test -s err &&
+       sed "s/commit-signing/commit-strip-signing/" output | (
+               cd new &&
+               git fast-import &&
+               STRIPPED=$(git rev-parse --verify refs/heads/commit-strip-signing) &&
+               test $COMMIT_SIGNING != $STRIPPED
+       )
+
+'
+
 test_expect_success 'setup submodule' '
 
        test_config_global protocol.file.allow always &&
        git checkout -f main &&
+       test_might_fail git update-ref -d refs/heads/commit-signing &&
        mkdir sub &&
        (
                cd sub &&