Andrew's git - gitweb.git/blob

   1#include "cache.h"
   2#include "config.h"
   3#include "run-command.h"
   4#include "strbuf.h"
   5#include "gpg-interface.h"
   6#include "sigchain.h"
   7#include "tempfile.h"
   8
   9static char *configured_signing_key;
  10struct gpg_format {
  11        const char *name;
  12        const char *program;
  13        const char **verify_args;
  14        const char **sigs;
  15};
  16
  17static const char *openpgp_verify_args[] = {
  18        "--keyid-format=long",
  19        NULL
  20};
  21static const char *openpgp_sigs[] = {
  22        "-----BEGIN PGP SIGNATURE-----",
  23        "-----BEGIN PGP MESSAGE-----",
  24        NULL
  25};
  26
  27static const char *x509_verify_args[] = {
  28        NULL
  29};
  30static const char *x509_sigs[] = {
  31        "-----BEGIN SIGNED MESSAGE-----",
  32        NULL
  33};
  34
  35static struct gpg_format gpg_format[] = {
  36        { .name = "openpgp", .program = "gpg",
  37          .verify_args = openpgp_verify_args,
  38          .sigs = openpgp_sigs
  39        },
  40        { .name = "x509", .program = "gpgsm",
  41          .verify_args = x509_verify_args,
  42          .sigs = x509_sigs
  43        },
  44};
  45
  46static struct gpg_format *use_format = &gpg_format[0];
  47
  48static struct gpg_format *get_format_by_name(const char *str)
  49{
  50        int i;
  51
  52        for (i = 0; i < ARRAY_SIZE(gpg_format); i++)
  53                if (!strcmp(gpg_format[i].name, str))
  54                        return gpg_format + i;
  55        return NULL;
  56}
  57
  58static struct gpg_format *get_format_by_sig(const char *sig)
  59{
  60        int i, j;
  61
  62        for (i = 0; i < ARRAY_SIZE(gpg_format); i++)
  63                for (j = 0; gpg_format[i].sigs[j]; j++)
  64                        if (starts_with(sig, gpg_format[i].sigs[j]))
  65                                return gpg_format + i;
  66        return NULL;
  67}
  68
  69void signature_check_clear(struct signature_check *sigc)
  70{
  71        FREE_AND_NULL(sigc->payload);
  72        FREE_AND_NULL(sigc->gpg_output);
  73        FREE_AND_NULL(sigc->gpg_status);
  74        FREE_AND_NULL(sigc->signer);
  75        FREE_AND_NULL(sigc->key);
  76        FREE_AND_NULL(sigc->fingerprint);
  77        FREE_AND_NULL(sigc->primary_key_fingerprint);
  78}
  79
  80/* An exclusive status -- only one of them can appear in output */
  81#define GPG_STATUS_EXCLUSIVE    (1<<0)
  82/* The status includes key identifier */
  83#define GPG_STATUS_KEYID        (1<<1)
  84/* The status includes user identifier */
  85#define GPG_STATUS_UID          (1<<2)
  86/* The status includes key fingerprints */
  87#define GPG_STATUS_FINGERPRINT  (1<<3)
  88
  89/* Short-hand for standard exclusive *SIG status with keyid & UID */
  90#define GPG_STATUS_STDSIG       (GPG_STATUS_EXCLUSIVE|GPG_STATUS_KEYID|GPG_STATUS_UID)
  91
  92static struct {
  93        char result;
  94        const char *check;
  95        unsigned int flags;
  96} sigcheck_gpg_status[] = {
  97        { 'G', "GOODSIG ", GPG_STATUS_STDSIG },
  98        { 'B', "BADSIG ", GPG_STATUS_STDSIG },
  99        { 'U', "TRUST_NEVER", 0 },
 100        { 'U', "TRUST_UNDEFINED", 0 },
 101        { 'E', "ERRSIG ", GPG_STATUS_EXCLUSIVE|GPG_STATUS_KEYID },
 102        { 'X', "EXPSIG ", GPG_STATUS_STDSIG },
 103        { 'Y', "EXPKEYSIG ", GPG_STATUS_STDSIG },
 104        { 'R', "REVKEYSIG ", GPG_STATUS_STDSIG },
 105        { 0, "VALIDSIG ", GPG_STATUS_FINGERPRINT },
 106};
 107
 108static void parse_gpg_output(struct signature_check *sigc)
 109{
 110        const char *buf = sigc->gpg_status;
 111        const char *line, *next;
 112        int i, j;
 113        int seen_exclusive_status = 0;
 114
 115        /* Iterate over all lines */
 116        for (line = buf; *line; line = strchrnul(line+1, '\n')) {
 117                while (*line == '\n')
 118                        line++;
 119                if (!*line)
 120                        break;
 121
 122                /* Skip lines that don't start with GNUPG status */
 123                if (!skip_prefix(line, "[GNUPG:] ", &line))
 124                        continue;
 125
 126                /* Iterate over all search strings */
 127                for (i = 0; i < ARRAY_SIZE(sigcheck_gpg_status); i++) {
 128                        if (skip_prefix(line, sigcheck_gpg_status[i].check, &line)) {
 129                                if (sigcheck_gpg_status[i].flags & GPG_STATUS_EXCLUSIVE) {
 130                                        if (seen_exclusive_status++)
 131                                                goto found_duplicate_status;
 132                                }
 133
 134                                if (sigcheck_gpg_status[i].result)
 135                                        sigc->result = sigcheck_gpg_status[i].result;
 136                                /* Do we have key information? */
 137                                if (sigcheck_gpg_status[i].flags & GPG_STATUS_KEYID) {
 138                                        next = strchrnul(line, ' ');
 139                                        free(sigc->key);
 140                                        sigc->key = xmemdupz(line, next - line);
 141                                        /* Do we have signer information? */
 142                                        if (*next && (sigcheck_gpg_status[i].flags & GPG_STATUS_UID)) {
 143                                                line = next + 1;
 144                                                next = strchrnul(line, '\n');
 145                                                free(sigc->signer);
 146                                                sigc->signer = xmemdupz(line, next - line);
 147                                        }
 148                                }
 149                                /* Do we have fingerprint? */
 150                                if (sigcheck_gpg_status[i].flags & GPG_STATUS_FINGERPRINT) {
 151                                        next = strchrnul(line, ' ');
 152                                        free(sigc->fingerprint);
 153                                        sigc->fingerprint = xmemdupz(line, next - line);
 154
 155                                        /* Skip interim fields */
 156                                        for (j = 9; j > 0; j--) {
 157                                                if (!*next)
 158                                                        break;
 159                                                line = next + 1;
 160                                                next = strchrnul(line, ' ');
 161                                        }
 162
 163                                        next = strchrnul(line, '\n');
 164                                        free(sigc->primary_key_fingerprint);
 165                                        sigc->primary_key_fingerprint = xmemdupz(line, next - line);
 166                                }
 167
 168                                break;
 169                        }
 170                }
 171        }
 172        return;
 173
 174found_duplicate_status:
 175        /*
 176         * GOODSIG, BADSIG etc. can occur only once for each signature.
 177         * Therefore, if we had more than one then we're dealing with multiple
 178         * signatures.  We don't support them currently, and they're rather
 179         * hard to create, so something is likely fishy and we should reject
 180         * them altogether.
 181         */
 182        sigc->result = 'E';
 183        /* Clear partial data to avoid confusion */
 184        FREE_AND_NULL(sigc->primary_key_fingerprint);
 185        FREE_AND_NULL(sigc->fingerprint);
 186        FREE_AND_NULL(sigc->signer);
 187        FREE_AND_NULL(sigc->key);
 188}
 189
 190int check_signature(const char *payload, size_t plen, const char *signature,
 191        size_t slen, struct signature_check *sigc)
 192{
 193        struct strbuf gpg_output = STRBUF_INIT;
 194        struct strbuf gpg_status = STRBUF_INIT;
 195        int status;
 196
 197        sigc->result = 'N';
 198
 199        status = verify_signed_buffer(payload, plen, signature, slen,
 200                                      &gpg_output, &gpg_status);
 201        if (status && !gpg_output.len)
 202                goto out;
 203        sigc->payload = xmemdupz(payload, plen);
 204        sigc->gpg_output = strbuf_detach(&gpg_output, NULL);
 205        sigc->gpg_status = strbuf_detach(&gpg_status, NULL);
 206        parse_gpg_output(sigc);
 207        status |= sigc->result != 'G' && sigc->result != 'U';
 208
 209 out:
 210        strbuf_release(&gpg_status);
 211        strbuf_release(&gpg_output);
 212
 213        return !!status;
 214}
 215
 216void print_signature_buffer(const struct signature_check *sigc, unsigned flags)
 217{
 218        const char *output = flags & GPG_VERIFY_RAW ?
 219                sigc->gpg_status : sigc->gpg_output;
 220
 221        if (flags & GPG_VERIFY_VERBOSE && sigc->payload)
 222                fputs(sigc->payload, stdout);
 223
 224        if (output)
 225                fputs(output, stderr);
 226}
 227
 228size_t parse_signature(const char *buf, size_t size)
 229{
 230        size_t len = 0;
 231        size_t match = size;
 232        while (len < size) {
 233                const char *eol;
 234
 235                if (get_format_by_sig(buf + len))
 236                        match = len;
 237
 238                eol = memchr(buf + len, '\n', size - len);
 239                len += eol ? eol - (buf + len) + 1 : size - len;
 240        }
 241        return match;
 242}
 243
 244void set_signing_key(const char *key)
 245{
 246        free(configured_signing_key);
 247        configured_signing_key = xstrdup(key);
 248}
 249
 250int git_gpg_config(const char *var, const char *value, void *cb)
 251{
 252        struct gpg_format *fmt = NULL;
 253        char *fmtname = NULL;
 254
 255        if (!strcmp(var, "user.signingkey")) {
 256                if (!value)
 257                        return config_error_nonbool(var);
 258                set_signing_key(value);
 259                return 0;
 260        }
 261
 262        if (!strcmp(var, "gpg.format")) {
 263                if (!value)
 264                        return config_error_nonbool(var);
 265                fmt = get_format_by_name(value);
 266                if (!fmt)
 267                        return error("unsupported value for %s: %s",
 268                                     var, value);
 269                use_format = fmt;
 270                return 0;
 271        }
 272
 273        if (!strcmp(var, "gpg.program") || !strcmp(var, "gpg.openpgp.program"))
 274                fmtname = "openpgp";
 275
 276        if (!strcmp(var, "gpg.x509.program"))
 277                fmtname = "x509";
 278
 279        if (fmtname) {
 280                fmt = get_format_by_name(fmtname);
 281                return git_config_string(&fmt->program, var, value);
 282        }
 283
 284        return 0;
 285}
 286
 287const char *get_signing_key(void)
 288{
 289        if (configured_signing_key)
 290                return configured_signing_key;
 291        return git_committer_info(IDENT_STRICT|IDENT_NO_DATE);
 292}
 293
 294int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key)
 295{
 296        struct child_process gpg = CHILD_PROCESS_INIT;
 297        int ret;
 298        size_t i, j, bottom;
 299        struct strbuf gpg_status = STRBUF_INIT;
 300
 301        argv_array_pushl(&gpg.args,
 302                         use_format->program,
 303                         "--status-fd=2",
 304                         "-bsau", signing_key,
 305                         NULL);
 306
 307        bottom = signature->len;
 308
 309        /*
 310         * When the username signingkey is bad, program could be terminated
 311         * because gpg exits without reading and then write gets SIGPIPE.
 312         */
 313        sigchain_push(SIGPIPE, SIG_IGN);
 314        ret = pipe_command(&gpg, buffer->buf, buffer->len,
 315                           signature, 1024, &gpg_status, 0);
 316        sigchain_pop(SIGPIPE);
 317
 318        ret |= !strstr(gpg_status.buf, "\n[GNUPG:] SIG_CREATED ");
 319        strbuf_release(&gpg_status);
 320        if (ret)
 321                return error(_("gpg failed to sign the data"));
 322
 323        /* Strip CR from the line endings, in case we are on Windows. */
 324        for (i = j = bottom; i < signature->len; i++)
 325                if (signature->buf[i] != '\r') {
 326                        if (i != j)
 327                                signature->buf[j] = signature->buf[i];
 328                        j++;
 329                }
 330        strbuf_setlen(signature, j);
 331
 332        return 0;
 333}
 334
 335int verify_signed_buffer(const char *payload, size_t payload_size,
 336                         const char *signature, size_t signature_size,
 337                         struct strbuf *gpg_output, struct strbuf *gpg_status)
 338{
 339        struct child_process gpg = CHILD_PROCESS_INIT;
 340        struct gpg_format *fmt;
 341        struct tempfile *temp;
 342        int ret;
 343        struct strbuf buf = STRBUF_INIT;
 344
 345        temp = mks_tempfile_t(".git_vtag_tmpXXXXXX");
 346        if (!temp)
 347                return error_errno(_("could not create temporary file"));
 348        if (write_in_full(temp->fd, signature, signature_size) < 0 ||
 349            close_tempfile_gently(temp) < 0) {
 350                error_errno(_("failed writing detached signature to '%s'"),
 351                            temp->filename.buf);
 352                delete_tempfile(&temp);
 353                return -1;
 354        }
 355
 356        fmt = get_format_by_sig(signature);
 357        if (!fmt)
 358                BUG("bad signature '%s'", signature);
 359
 360        argv_array_push(&gpg.args, fmt->program);
 361        argv_array_pushv(&gpg.args, fmt->verify_args);
 362        argv_array_pushl(&gpg.args,
 363                         "--status-fd=1",
 364                         "--verify", temp->filename.buf, "-",
 365                         NULL);
 366
 367        if (!gpg_status)
 368                gpg_status = &buf;
 369
 370        sigchain_push(SIGPIPE, SIG_IGN);
 371        ret = pipe_command(&gpg, payload, payload_size,
 372                           gpg_status, 0, gpg_output, 0);
 373        sigchain_pop(SIGPIPE);
 374
 375        delete_tempfile(&temp);
 376
 377        ret |= !strstr(gpg_status->buf, "\n[GNUPG:] GOODSIG ");
 378        strbuf_release(&buf); /* no matter it was used or not */
 379
 380        return ret;
 381}