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authorJunio C Hamano <gitster@pobox.com>2014-10-08 20:05:15 (GMT)
committerJunio C Hamano <gitster@pobox.com>2014-10-08 20:05:25 (GMT)
commitfb06b5280ea05d75515fa780cf08d4ec9d6fe101 (patch)
tree9d7c7032df370076149f31f3373e067b69248169 /builtin
parent325602ce120e7bd7321b9ed409b49b48fd20888e (diff)
parent6f5ef44e0d8933621fcd50127518557013002313 (diff)
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Merge branch 'jc/push-cert'
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 ...
Diffstat (limited to 'builtin')
-rw-r--r--builtin/push.c1
-rw-r--r--builtin/receive-pack.c393
-rw-r--r--builtin/send-pack.c4
3 files changed, 358 insertions, 40 deletions
diff --git a/builtin/push.c b/builtin/push.c
index f50e3d5..ae56f73 100644
--- a/builtin/push.c
+++ b/builtin/push.c
@@ -506,6 +506,7 @@ int cmd_push(int argc, const char **argv, const char *prefix)
OPT_BIT(0, "no-verify", &flags, N_("bypass pre-push hook"), TRANSPORT_PUSH_NO_HOOK),
OPT_BIT(0, "follow-tags", &flags, N_("push missing but relevant tags"),
TRANSPORT_PUSH_FOLLOW_TAGS),
+ OPT_BIT(0, "signed", &flags, N_("GPG sign the push"), TRANSPORT_PUSH_CERT),
OPT_END()
};
diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index daf0600..a01ac20 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -15,6 +15,8 @@
#include "connected.h"
#include "argv-array.h"
#include "version.h"
+#include "tag.h"
+#include "gpg-interface.h"
#include "sigchain.h"
static const char receive_pack_usage[] = "git receive-pack <git-dir>";
@@ -42,11 +44,27 @@ static int prefer_ofs_delta = 1;
static int auto_update_server_info;
static int auto_gc = 1;
static int fix_thin = 1;
+static int stateless_rpc;
+static const char *service_dir;
static const char *head_name;
static void *head_name_to_free;
static int sent_capabilities;
static int shallow_update;
static const char *alt_shallow_file;
+static struct strbuf push_cert = STRBUF_INIT;
+static unsigned char push_cert_sha1[20];
+static struct signature_check sigcheck;
+static const char *push_cert_nonce;
+static const char *cert_nonce_seed;
+
+static const char *NONCE_UNSOLICITED = "UNSOLICITED";
+static const char *NONCE_BAD = "BAD";
+static const char *NONCE_MISSING = "MISSING";
+static const char *NONCE_OK = "OK";
+static const char *NONCE_SLOP = "SLOP";
+static const char *nonce_status;
+static long nonce_stamp_slop;
+static unsigned long nonce_stamp_slop_limit;
static enum deny_action parse_deny_action(const char *var, const char *value)
{
@@ -130,6 +148,14 @@ static int receive_pack_config(const char *var, const char *value, void *cb)
return 0;
}
+ if (strcmp(var, "receive.certnonceseed") == 0)
+ return git_config_string(&cert_nonce_seed, var, value);
+
+ if (strcmp(var, "receive.certnonceslop") == 0) {
+ nonce_stamp_slop_limit = git_config_ulong(var, value);
+ return 0;
+ }
+
return git_default_config(var, value, cb);
}
@@ -138,15 +164,23 @@ static void show_ref(const char *path, const unsigned char *sha1)
if (ref_is_hidden(path))
return;
- if (sent_capabilities)
+ if (sent_capabilities) {
packet_write(1, "%s %s\n", sha1_to_hex(sha1), path);
- else
- packet_write(1, "%s %s%c%s%s agent=%s\n",
- sha1_to_hex(sha1), path, 0,
- " report-status delete-refs side-band-64k quiet",
- prefer_ofs_delta ? " ofs-delta" : "",
- git_user_agent_sanitized());
- sent_capabilities = 1;
+ } else {
+ struct strbuf cap = STRBUF_INIT;
+
+ strbuf_addstr(&cap,
+ "report-status delete-refs side-band-64k quiet");
+ if (prefer_ofs_delta)
+ strbuf_addstr(&cap, " ofs-delta");
+ if (push_cert_nonce)
+ strbuf_addf(&cap, " push-cert=%s", push_cert_nonce);
+ strbuf_addf(&cap, " agent=%s", git_user_agent_sanitized());
+ packet_write(1, "%s %s%c%s\n",
+ sha1_to_hex(sha1), path, 0, cap.buf);
+ strbuf_release(&cap);
+ sent_capabilities = 1;
+ }
}
static int show_ref_cb(const char *path, const unsigned char *sha1, int flag, void *unused)
@@ -253,6 +287,222 @@ static int copy_to_sideband(int in, int out, void *arg)
return 0;
}
+#define HMAC_BLOCK_SIZE 64
+
+static void hmac_sha1(unsigned char *out,
+ const char *key_in, size_t key_len,
+ const char *text, size_t text_len)
+{
+ unsigned char key[HMAC_BLOCK_SIZE];
+ unsigned char k_ipad[HMAC_BLOCK_SIZE];
+ unsigned char k_opad[HMAC_BLOCK_SIZE];
+ int i;
+ git_SHA_CTX ctx;
+
+ /* RFC 2104 2. (1) */
+ memset(key, '\0', HMAC_BLOCK_SIZE);
+ if (HMAC_BLOCK_SIZE < key_len) {
+ git_SHA1_Init(&ctx);
+ git_SHA1_Update(&ctx, key_in, key_len);
+ git_SHA1_Final(key, &ctx);
+ } else {
+ memcpy(key, key_in, key_len);
+ }
+
+ /* RFC 2104 2. (2) & (5) */
+ for (i = 0; i < sizeof(key); i++) {
+ k_ipad[i] = key[i] ^ 0x36;
+ k_opad[i] = key[i] ^ 0x5c;
+ }
+
+ /* RFC 2104 2. (3) & (4) */
+ git_SHA1_Init(&ctx);
+ git_SHA1_Update(&ctx, k_ipad, sizeof(k_ipad));
+ git_SHA1_Update(&ctx, text, text_len);
+ git_SHA1_Final(out, &ctx);
+
+ /* RFC 2104 2. (6) & (7) */
+ git_SHA1_Init(&ctx);
+ git_SHA1_Update(&ctx, k_opad, sizeof(k_opad));
+ git_SHA1_Update(&ctx, out, 20);
+ git_SHA1_Final(out, &ctx);
+}
+
+static char *prepare_push_cert_nonce(const char *path, unsigned long stamp)
+{
+ struct strbuf buf = STRBUF_INIT;
+ unsigned char sha1[20];
+
+ strbuf_addf(&buf, "%s:%lu", path, stamp);
+ hmac_sha1(sha1, buf.buf, buf.len, cert_nonce_seed, strlen(cert_nonce_seed));;
+ strbuf_release(&buf);
+
+ /* RFC 2104 5. HMAC-SHA1-80 */
+ strbuf_addf(&buf, "%lu-%.*s", stamp, 20, sha1_to_hex(sha1));
+ return strbuf_detach(&buf, NULL);
+}
+
+/*
+ * NEEDSWORK: reuse find_commit_header() from jk/commit-author-parsing
+ * after dropping "_commit" from its name and possibly moving it out
+ * of commit.c
+ */
+static char *find_header(const char *msg, size_t len, const char *key)
+{
+ int key_len = strlen(key);
+ const char *line = msg;
+
+ while (line && line < msg + len) {
+ const char *eol = strchrnul(line, '\n');
+
+ if ((msg + len <= eol) || line == eol)
+ return NULL;
+ if (line + key_len < eol &&
+ !memcmp(line, key, key_len) && line[key_len] == ' ') {
+ int offset = key_len + 1;
+ return xmemdupz(line + offset, (eol - line) - offset);
+ }
+ line = *eol ? eol + 1 : NULL;
+ }
+ return NULL;
+}
+
+static const char *check_nonce(const char *buf, size_t len)
+{
+ char *nonce = find_header(buf, len, "nonce");
+ unsigned long stamp, ostamp;
+ char *bohmac, *expect = NULL;
+ const char *retval = NONCE_BAD;
+
+ if (!nonce) {
+ retval = NONCE_MISSING;
+ goto leave;
+ } else if (!push_cert_nonce) {
+ retval = NONCE_UNSOLICITED;
+ goto leave;
+ } else if (!strcmp(push_cert_nonce, nonce)) {
+ retval = NONCE_OK;
+ goto leave;
+ }
+
+ if (!stateless_rpc) {
+ /* returned nonce MUST match what we gave out earlier */
+ retval = NONCE_BAD;
+ goto leave;
+ }
+
+ /*
+ * In stateless mode, we may be receiving a nonce issued by
+ * another instance of the server that serving the same
+ * repository, and the timestamps may not match, but the
+ * nonce-seed and dir should match, so we can recompute and
+ * report the time slop.
+ *
+ * In addition, when a nonce issued by another instance has
+ * timestamp within receive.certnonceslop seconds, we pretend
+ * as if we issued that nonce when reporting to the hook.
+ */
+
+ /* nonce is concat(<seconds-since-epoch>, "-", <hmac>) */
+ if (*nonce <= '0' || '9' < *nonce) {
+ retval = NONCE_BAD;
+ goto leave;
+ }
+ stamp = strtoul(nonce, &bohmac, 10);
+ if (bohmac == nonce || bohmac[0] != '-') {
+ retval = NONCE_BAD;
+ goto leave;
+ }
+
+ expect = prepare_push_cert_nonce(service_dir, stamp);
+ if (strcmp(expect, nonce)) {
+ /* Not what we would have signed earlier */
+ retval = NONCE_BAD;
+ goto leave;
+ }
+
+ /*
+ * By how many seconds is this nonce stale? Negative value
+ * would mean it was issued by another server with its clock
+ * skewed in the future.
+ */
+ ostamp = strtoul(push_cert_nonce, NULL, 10);
+ nonce_stamp_slop = (long)ostamp - (long)stamp;
+
+ if (nonce_stamp_slop_limit &&
+ abs(nonce_stamp_slop) <= nonce_stamp_slop_limit) {
+ /*
+ * Pretend as if the received nonce (which passes the
+ * HMAC check, so it is not a forged by third-party)
+ * is what we issued.
+ */
+ free((void *)push_cert_nonce);
+ push_cert_nonce = xstrdup(nonce);
+ retval = NONCE_OK;
+ } else {
+ retval = NONCE_SLOP;
+ }
+
+leave:
+ free(nonce);
+ free(expect);
+ return retval;
+}
+
+static void prepare_push_cert_sha1(struct child_process *proc)
+{
+ static int already_done;
+ struct argv_array env = ARGV_ARRAY_INIT;
+
+ if (!push_cert.len)
+ return;
+
+ if (!already_done) {
+ struct strbuf gpg_output = STRBUF_INIT;
+ struct strbuf gpg_status = STRBUF_INIT;
+ int bogs /* beginning_of_gpg_sig */;
+
+ already_done = 1;
+ if (write_sha1_file(push_cert.buf, push_cert.len, "blob", push_cert_sha1))
+ hashclr(push_cert_sha1);
+
+ memset(&sigcheck, '\0', sizeof(sigcheck));
+ sigcheck.result = 'N';
+
+ bogs = parse_signature(push_cert.buf, push_cert.len);
+ if (verify_signed_buffer(push_cert.buf, bogs,
+ push_cert.buf + bogs, push_cert.len - bogs,
+ &gpg_output, &gpg_status) < 0) {
+ ; /* error running gpg */
+ } else {
+ sigcheck.payload = push_cert.buf;
+ sigcheck.gpg_output = gpg_output.buf;
+ sigcheck.gpg_status = gpg_status.buf;
+ parse_gpg_output(&sigcheck);
+ }
+
+ strbuf_release(&gpg_output);
+ strbuf_release(&gpg_status);
+ nonce_status = check_nonce(push_cert.buf, bogs);
+ }
+ if (!is_null_sha1(push_cert_sha1)) {
+ argv_array_pushf(&env, "GIT_PUSH_CERT=%s", sha1_to_hex(push_cert_sha1));
+ argv_array_pushf(&env, "GIT_PUSH_CERT_SIGNER=%s",
+ sigcheck.signer ? sigcheck.signer : "");
+ argv_array_pushf(&env, "GIT_PUSH_CERT_KEY=%s",
+ sigcheck.key ? sigcheck.key : "");
+ argv_array_pushf(&env, "GIT_PUSH_CERT_STATUS=%c", sigcheck.result);
+ if (push_cert_nonce) {
+ argv_array_pushf(&env, "GIT_PUSH_CERT_NONCE=%s", push_cert_nonce);
+ argv_array_pushf(&env, "GIT_PUSH_CERT_NONCE_STATUS=%s", nonce_status);
+ if (nonce_status == NONCE_SLOP)
+ argv_array_pushf(&env, "GIT_PUSH_CERT_NONCE_SLOP=%ld",
+ nonce_stamp_slop);
+ }
+ proc->env = env.argv;
+ }
+}
+
typedef int (*feed_fn)(void *, const char **, size_t *);
static int run_and_feed_hook(const char *hook_name, feed_fn feed, void *feed_state)
{
@@ -271,6 +521,8 @@ static int run_and_feed_hook(const char *hook_name, feed_fn feed, void *feed_sta
proc.in = -1;
proc.stdout_to_stderr = 1;
+ prepare_push_cert_sha1(&proc);
+
if (use_sideband) {
memset(&muxer, 0, sizeof(muxer));
muxer.proc = copy_to_sideband;
@@ -841,40 +1093,79 @@ static void execute_commands(struct command *commands,
"the reported refs above");
}
+static struct command **queue_command(struct command **tail,
+ const char *line,
+ int linelen)
+{
+ unsigned char old_sha1[20], new_sha1[20];
+ struct command *cmd;
+ const char *refname;
+ int reflen;
+
+ if (linelen < 83 ||
+ line[40] != ' ' ||
+ line[81] != ' ' ||
+ get_sha1_hex(line, old_sha1) ||
+ get_sha1_hex(line + 41, new_sha1))
+ die("protocol error: expected old/new/ref, got '%s'", line);
+
+ refname = line + 82;
+ reflen = linelen - 82;
+ cmd = xcalloc(1, sizeof(struct command) + reflen + 1);
+ hashcpy(cmd->old_sha1, old_sha1);
+ hashcpy(cmd->new_sha1, new_sha1);
+ memcpy(cmd->ref_name, refname, reflen);
+ cmd->ref_name[reflen] = '\0';
+ *tail = cmd;
+ return &cmd->next;
+}
+
+static void queue_commands_from_cert(struct command **tail,
+ struct strbuf *push_cert)
+{
+ const char *boc, *eoc;
+
+ if (*tail)
+ die("protocol error: got both push certificate and unsigned commands");
+
+ boc = strstr(push_cert->buf, "\n\n");
+ if (!boc)
+ die("malformed push certificate %.*s", 100, push_cert->buf);
+ else
+ boc += 2;
+ eoc = push_cert->buf + parse_signature(push_cert->buf, push_cert->len);
+
+ while (boc < eoc) {
+ const char *eol = memchr(boc, '\n', eoc - boc);
+ tail = queue_command(tail, boc, eol ? eol - boc : eoc - eol);
+ boc = eol ? eol + 1 : eoc;
+ }
+}
+
static struct command *read_head_info(struct sha1_array *shallow)
{
struct command *commands = NULL;
struct command **p = &commands;
for (;;) {
char *line;
- unsigned char old_sha1[20], new_sha1[20];
- struct command *cmd;
- char *refname;
- int len, reflen;
+ int len, linelen;
line = packet_read_line(0, &len);
if (!line)
break;
if (len == 48 && starts_with(line, "shallow ")) {
- if (get_sha1_hex(line + 8, old_sha1))
- die("protocol error: expected shallow sha, got '%s'", line + 8);
- sha1_array_append(shallow, old_sha1);
+ unsigned char sha1[20];
+ if (get_sha1_hex(line + 8, sha1))
+ die("protocol error: expected shallow sha, got '%s'",
+ line + 8);
+ sha1_array_append(shallow, sha1);
continue;
}
- if (len < 83 ||
- line[40] != ' ' ||
- line[81] != ' ' ||
- get_sha1_hex(line, old_sha1) ||
- get_sha1_hex(line + 41, new_sha1))
- die("protocol error: expected old/new/ref, got '%s'",
- line);
-
- refname = line + 82;
- reflen = strlen(refname);
- if (reflen + 82 < len) {
- const char *feature_list = refname + reflen + 1;
+ linelen = strlen(line);
+ if (linelen < len) {
+ const char *feature_list = line + linelen + 1;
if (parse_feature_request(feature_list, "report-status"))
report_status = 1;
if (parse_feature_request(feature_list, "side-band-64k"))
@@ -882,13 +1173,34 @@ static struct command *read_head_info(struct sha1_array *shallow)
if (parse_feature_request(feature_list, "quiet"))
quiet = 1;
}
- cmd = xcalloc(1, sizeof(struct command) + len - 80);
- hashcpy(cmd->old_sha1, old_sha1);
- hashcpy(cmd->new_sha1, new_sha1);
- memcpy(cmd->ref_name, line + 82, len - 81);
- *p = cmd;
- p = &cmd->next;
+
+ if (!strcmp(line, "push-cert")) {
+ int true_flush = 0;
+ char certbuf[1024];
+
+ for (;;) {
+ len = packet_read(0, NULL, NULL,
+ certbuf, sizeof(certbuf), 0);
+ if (!len) {
+ true_flush = 1;
+ break;
+ }
+ if (!strcmp(certbuf, "push-cert-end\n"))
+ break; /* end of cert */
+ strbuf_addstr(&push_cert, certbuf);
+ }
+
+ if (true_flush)
+ break;
+ continue;
+ }
+
+ p = queue_command(p, line, linelen);
}
+
+ if (push_cert.len)
+ queue_commands_from_cert(p, &push_cert);
+
return commands;
}
@@ -1129,9 +1441,7 @@ static int delete_only(struct command *commands)
int cmd_receive_pack(int argc, const char **argv, const char *prefix)
{
int advertise_refs = 0;
- int stateless_rpc = 0;
int i;
- const char *dir = NULL;
struct command *commands;
struct sha1_array shallow = SHA1_ARRAY_INIT;
struct sha1_array ref = SHA1_ARRAY_INIT;
@@ -1164,19 +1474,21 @@ int cmd_receive_pack(int argc, const char **argv, const char *prefix)
usage(receive_pack_usage);
}
- if (dir)
+ if (service_dir)
usage(receive_pack_usage);
- dir = arg;
+ service_dir = arg;
}
- if (!dir)
+ if (!service_dir)
usage(receive_pack_usage);
setup_path();
- if (!enter_repo(dir, 0))
- die("'%s' does not appear to be a git repository", dir);
+ if (!enter_repo(service_dir, 0))
+ die("'%s' does not appear to be a git repository", service_dir);
git_config(receive_pack_config, NULL);
+ if (cert_nonce_seed)
+ push_cert_nonce = prepare_push_cert_nonce(service_dir, time(NULL));
if (0 <= transfer_unpack_limit)
unpack_limit = transfer_unpack_limit;
@@ -1221,5 +1533,6 @@ int cmd_receive_pack(int argc, const char **argv, const char *prefix)
packet_flush(1);
sha1_array_clear(&shallow);
sha1_array_clear(&ref);
+ free((void *)push_cert_nonce);
return 0;
}
diff --git a/builtin/send-pack.c b/builtin/send-pack.c
index 4b1bc0f..b564a77 100644
--- a/builtin/send-pack.c
+++ b/builtin/send-pack.c
@@ -154,6 +154,10 @@ int cmd_send_pack(int argc, const char **argv, const char *prefix)
args.verbose = 1;
continue;
}
+ if (!strcmp(arg, "--signed")) {
+ args.push_cert = 1;
+ continue;
+ }
if (!strcmp(arg, "--progress")) {
progress = 1;
continue;