From 4838f62c8caffbfe5d7d39cad4e8aeb2a2d57da8 Mon Sep 17 00:00:00 2001 From: Fabian Stelzer Date: Fri, 10 Sep 2021 20:07:38 +0000 Subject: [PATCH] ssh signing: provide a textual signing_key_id For ssh the user.signingkey can be a filename/path or even a literal ssh pubkey. In push certs and textual output we prefer the ssh fingerprint instead. Signed-off-by: Fabian Stelzer Signed-off-by: Junio C Hamano --- gpg-interface.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++ gpg-interface.h | 6 ++++++ send-pack.c | 8 +++---- 3 files changed, 66 insertions(+), 4 deletions(-) diff --git a/gpg-interface.c b/gpg-interface.c index 3a0cca1b1d2..0f1c6a02e53 100644 --- a/gpg-interface.c +++ b/gpg-interface.c @@ -24,6 +24,7 @@ struct gpg_format { int (*sign_buffer)(struct strbuf *buffer, struct strbuf *signature, const char *signing_key); const char *(*get_default_key)(void); + const char *(*get_key_id)(void); }; static const char *openpgp_verify_args[] = { @@ -61,6 +62,8 @@ static int sign_buffer_ssh(struct strbuf *buffer, struct strbuf *signature, static const char *get_default_ssh_signing_key(void); +static const char *get_ssh_key_id(void); + static struct gpg_format gpg_format[] = { { .name = "openpgp", @@ -70,6 +73,7 @@ static struct gpg_format gpg_format[] = { .verify_signed_buffer = verify_gpg_signed_buffer, .sign_buffer = sign_buffer_gpg, .get_default_key = NULL, + .get_key_id = NULL, }, { .name = "x509", @@ -79,6 +83,7 @@ static struct gpg_format gpg_format[] = { .verify_signed_buffer = verify_gpg_signed_buffer, .sign_buffer = sign_buffer_gpg, .get_default_key = NULL, + .get_key_id = NULL, }, { .name = "ssh", @@ -88,6 +93,7 @@ static struct gpg_format gpg_format[] = { .verify_signed_buffer = NULL, /* TODO */ .sign_buffer = sign_buffer_ssh, .get_default_key = get_default_ssh_signing_key, + .get_key_id = get_ssh_key_id, }, }; @@ -484,6 +490,41 @@ int git_gpg_config(const char *var, const char *value, void *cb) return 0; } +static char *get_ssh_key_fingerprint(const char *signing_key) +{ + struct child_process ssh_keygen = CHILD_PROCESS_INIT; + int ret = -1; + struct strbuf fingerprint_stdout = STRBUF_INIT; + struct strbuf **fingerprint; + + /* + * With SSH Signing this can contain a filename or a public key + * For textual representation we usually want a fingerprint + */ + if (starts_with(signing_key, "ssh-")) { + strvec_pushl(&ssh_keygen.args, "ssh-keygen", "-lf", "-", NULL); + ret = pipe_command(&ssh_keygen, signing_key, + strlen(signing_key), &fingerprint_stdout, 0, + NULL, 0); + } else { + strvec_pushl(&ssh_keygen.args, "ssh-keygen", "-lf", + configured_signing_key, NULL); + ret = pipe_command(&ssh_keygen, NULL, 0, &fingerprint_stdout, 0, + NULL, 0); + } + + if (!!ret) + die_errno(_("failed to get the ssh fingerprint for key '%s'"), + signing_key); + + fingerprint = strbuf_split_max(&fingerprint_stdout, ' ', 3); + if (!fingerprint[1]) + die_errno(_("failed to get the ssh fingerprint for key '%s'"), + signing_key); + + return strbuf_detach(fingerprint[1], NULL); +} + /* Returns the first public key from an ssh-agent to use for signing */ static const char *get_default_ssh_signing_key(void) { @@ -532,6 +573,21 @@ static const char *get_default_ssh_signing_key(void) return default_key; } +static const char *get_ssh_key_id(void) { + return get_ssh_key_fingerprint(get_signing_key()); +} + +/* Returns a textual but unique representation of the signing key */ +const char *get_signing_key_id(void) +{ + if (use_format->get_key_id) { + return use_format->get_key_id(); + } + + /* GPG/GPGSM only store a key id on this variable */ + return get_signing_key(); +} + const char *get_signing_key(void) { if (configured_signing_key) diff --git a/gpg-interface.h b/gpg-interface.h index feac4decf8b..beefacbb1e9 100644 --- a/gpg-interface.h +++ b/gpg-interface.h @@ -64,6 +64,12 @@ int sign_buffer(struct strbuf *buffer, struct strbuf *signature, int git_gpg_config(const char *, const char *, void *); void set_signing_key(const char *); const char *get_signing_key(void); + +/* + * Returns a textual unique representation of the signing key in use + * Either a GPG KeyID or a SSH Key Fingerprint + */ +const char *get_signing_key_id(void); int check_signature(const char *payload, size_t plen, const char *signature, size_t slen, struct signature_check *sigc); diff --git a/send-pack.c b/send-pack.c index 5a79e0e7110..50cca7e439b 100644 --- a/send-pack.c +++ b/send-pack.c @@ -341,13 +341,13 @@ static int generate_push_cert(struct strbuf *req_buf, { const struct ref *ref; struct string_list_item *item; - char *signing_key = xstrdup(get_signing_key()); + char *signing_key_id = xstrdup(get_signing_key_id()); const char *cp, *np; struct strbuf cert = STRBUF_INIT; int update_seen = 0; strbuf_addstr(&cert, "certificate version 0.1\n"); - strbuf_addf(&cert, "pusher %s ", signing_key); + strbuf_addf(&cert, "pusher %s ", signing_key_id); datestamp(&cert); strbuf_addch(&cert, '\n'); if (args->url && *args->url) { @@ -374,7 +374,7 @@ static int generate_push_cert(struct strbuf *req_buf, if (!update_seen) goto free_return; - if (sign_buffer(&cert, &cert, signing_key)) + if (sign_buffer(&cert, &cert, get_signing_key())) die(_("failed to sign the push certificate")); packet_buf_write(req_buf, "push-cert%c%s", 0, cap_string); @@ -386,7 +386,7 @@ static int generate_push_cert(struct strbuf *req_buf, packet_buf_write(req_buf, "push-cert-end\n"); free_return: - free(signing_key); + free(signing_key_id); strbuf_release(&cert); return update_seen; }