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![Junio C Hamano](/assets/img/avatar_default.png)
Allow "git push" request to be signed, so that it can be verified and audited, using the GPG signature of the person who pushed, that the tips of branches at a public repository really point the commits the pusher wanted to, without having to "trust" the server. * jc/push-cert: (24 commits) receive-pack::hmac_sha1(): copy the entire SHA-1 hash out signed push: allow stale nonce in stateless mode signed push: teach smart-HTTP to pass "git push --signed" around signed push: fortify against replay attacks signed push: add "pushee" header to push certificate signed push: remove duplicated protocol info send-pack: send feature request on push-cert packet receive-pack: GPG-validate push certificates push: the beginning of "git push --signed" pack-protocol doc: typofix for PKT-LINE gpg-interface: move parse_signature() to where it should be gpg-interface: move parse_gpg_output() to where it should be send-pack: clarify that cmds_sent is a boolean send-pack: refactor inspecting and resetting status and sending commands send-pack: rename "new_refs" to "need_pack_data" receive-pack: factor out capability string generation send-pack: factor out capability string generation send-pack: always send capabilities send-pack: refactor decision to send update per ref send-pack: move REF_STATUS_REJECT_NODELETE logic a bit higher ...
224 lines
5.6 KiB
C
224 lines
5.6 KiB
C
#include "cache.h"
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#include "run-command.h"
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#include "strbuf.h"
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#include "gpg-interface.h"
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#include "sigchain.h"
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static char *configured_signing_key;
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static const char *gpg_program = "gpg";
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#define PGP_SIGNATURE "-----BEGIN PGP SIGNATURE-----"
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#define PGP_MESSAGE "-----BEGIN PGP MESSAGE-----"
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void signature_check_clear(struct signature_check *sigc)
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{
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free(sigc->payload);
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free(sigc->gpg_output);
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free(sigc->gpg_status);
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free(sigc->signer);
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free(sigc->key);
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sigc->payload = NULL;
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sigc->gpg_output = NULL;
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sigc->gpg_status = NULL;
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sigc->signer = NULL;
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sigc->key = NULL;
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}
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static struct {
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char result;
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const char *check;
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} sigcheck_gpg_status[] = {
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{ 'G', "\n[GNUPG:] GOODSIG " },
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{ 'B', "\n[GNUPG:] BADSIG " },
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{ 'U', "\n[GNUPG:] TRUST_NEVER" },
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{ 'U', "\n[GNUPG:] TRUST_UNDEFINED" },
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};
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void parse_gpg_output(struct signature_check *sigc)
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{
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const char *buf = sigc->gpg_status;
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int i;
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/* Iterate over all search strings */
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for (i = 0; i < ARRAY_SIZE(sigcheck_gpg_status); i++) {
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const char *found, *next;
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if (!skip_prefix(buf, sigcheck_gpg_status[i].check + 1, &found)) {
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found = strstr(buf, sigcheck_gpg_status[i].check);
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if (!found)
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continue;
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found += strlen(sigcheck_gpg_status[i].check);
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}
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sigc->result = sigcheck_gpg_status[i].result;
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/* The trust messages are not followed by key/signer information */
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if (sigc->result != 'U') {
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sigc->key = xmemdupz(found, 16);
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found += 17;
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next = strchrnul(found, '\n');
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sigc->signer = xmemdupz(found, next - found);
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}
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}
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}
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/*
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* Look at GPG signed content (e.g. a signed tag object), whose
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* payload is followed by a detached signature on it. Return the
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* offset where the embedded detached signature begins, or the end of
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* the data when there is no such signature.
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*/
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size_t parse_signature(const char *buf, unsigned long size)
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{
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char *eol;
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size_t len = 0;
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while (len < size && !starts_with(buf + len, PGP_SIGNATURE) &&
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!starts_with(buf + len, PGP_MESSAGE)) {
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eol = memchr(buf + len, '\n', size - len);
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len += eol ? eol - (buf + len) + 1 : size - len;
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}
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return len;
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}
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void set_signing_key(const char *key)
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{
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free(configured_signing_key);
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configured_signing_key = xstrdup(key);
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}
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int git_gpg_config(const char *var, const char *value, void *cb)
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{
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if (!strcmp(var, "user.signingkey")) {
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set_signing_key(value);
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}
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if (!strcmp(var, "gpg.program")) {
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if (!value)
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return config_error_nonbool(var);
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gpg_program = xstrdup(value);
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}
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return 0;
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}
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const char *get_signing_key(void)
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{
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if (configured_signing_key)
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return configured_signing_key;
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return git_committer_info(IDENT_STRICT|IDENT_NO_DATE);
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}
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/*
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* Create a detached signature for the contents of "buffer" and append
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* it after "signature"; "buffer" and "signature" can be the same
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* strbuf instance, which would cause the detached signature appended
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* at the end.
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*/
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int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key)
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{
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struct child_process gpg = CHILD_PROCESS_INIT;
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const char *args[4];
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ssize_t len;
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size_t i, j, bottom;
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gpg.argv = args;
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gpg.in = -1;
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gpg.out = -1;
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args[0] = gpg_program;
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args[1] = "-bsau";
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args[2] = signing_key;
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args[3] = NULL;
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if (start_command(&gpg))
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return error(_("could not run gpg."));
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/*
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* When the username signingkey is bad, program could be terminated
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* because gpg exits without reading and then write gets SIGPIPE.
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*/
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sigchain_push(SIGPIPE, SIG_IGN);
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if (write_in_full(gpg.in, buffer->buf, buffer->len) != buffer->len) {
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close(gpg.in);
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close(gpg.out);
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finish_command(&gpg);
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return error(_("gpg did not accept the data"));
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}
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close(gpg.in);
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bottom = signature->len;
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len = strbuf_read(signature, gpg.out, 1024);
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close(gpg.out);
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sigchain_pop(SIGPIPE);
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if (finish_command(&gpg) || !len || len < 0)
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return error(_("gpg failed to sign the data"));
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/* Strip CR from the line endings, in case we are on Windows. */
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for (i = j = bottom; i < signature->len; i++)
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if (signature->buf[i] != '\r') {
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if (i != j)
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signature->buf[j] = signature->buf[i];
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j++;
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}
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strbuf_setlen(signature, j);
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return 0;
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}
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/*
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* Run "gpg" to see if the payload matches the detached signature.
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* gpg_output, when set, receives the diagnostic output from GPG.
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* gpg_status, when set, receives the status output from GPG.
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*/
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int verify_signed_buffer(const char *payload, size_t payload_size,
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const char *signature, size_t signature_size,
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struct strbuf *gpg_output, struct strbuf *gpg_status)
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{
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struct child_process gpg = CHILD_PROCESS_INIT;
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const char *args_gpg[] = {NULL, "--status-fd=1", "--verify", "FILE", "-", NULL};
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char path[PATH_MAX];
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int fd, ret;
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struct strbuf buf = STRBUF_INIT;
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struct strbuf *pbuf = &buf;
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args_gpg[0] = gpg_program;
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fd = git_mkstemp(path, PATH_MAX, ".git_vtag_tmpXXXXXX");
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if (fd < 0)
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return error(_("could not create temporary file '%s': %s"),
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path, strerror(errno));
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if (write_in_full(fd, signature, signature_size) < 0)
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return error(_("failed writing detached signature to '%s': %s"),
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path, strerror(errno));
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close(fd);
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gpg.argv = args_gpg;
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gpg.in = -1;
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gpg.out = -1;
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if (gpg_output)
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gpg.err = -1;
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args_gpg[3] = path;
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if (start_command(&gpg)) {
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unlink(path);
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return error(_("could not run gpg."));
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}
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write_in_full(gpg.in, payload, payload_size);
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close(gpg.in);
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if (gpg_output) {
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strbuf_read(gpg_output, gpg.err, 0);
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close(gpg.err);
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}
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if (gpg_status)
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pbuf = gpg_status;
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strbuf_read(pbuf, gpg.out, 0);
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close(gpg.out);
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ret = finish_command(&gpg);
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unlink_or_warn(path);
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ret |= !strstr(pbuf->buf, "\n[GNUPG:] GOODSIG ");
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strbuf_release(&buf); /* no matter it was used or not */
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return ret;
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}
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