Andrew's git - gitweb.git/blob

8ed274533f87198a74a3660809c25932fa43124a
   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                /* Skip lines that don't start with GNUPG status */
 120                if (!skip_prefix(line, "[GNUPG:] ", &line))
 121                        continue;
 122
 123                /* Iterate over all search strings */
 124                for (i = 0; i < ARRAY_SIZE(sigcheck_gpg_status); i++) {
 125                        if (skip_prefix(line, sigcheck_gpg_status[i].check, &line)) {
 126                                if (sigcheck_gpg_status[i].flags & GPG_STATUS_EXCLUSIVE) {
 127                                        if (seen_exclusive_status++)
 128                                                goto found_duplicate_status;
 129                                }
 130
 131                                if (sigcheck_gpg_status[i].result)
 132                                        sigc->result = sigcheck_gpg_status[i].result;
 133                                /* Do we have key information? */
 134                                if (sigcheck_gpg_status[i].flags & GPG_STATUS_KEYID) {
 135                                        next = strchrnul(line, ' ');
 136                                        free(sigc->key);
 137                                        sigc->key = xmemdupz(line, next - line);
 138                                        /* Do we have signer information? */
 139                                        if (*next && (sigcheck_gpg_status[i].flags & GPG_STATUS_UID)) {
 140                                                line = next + 1;
 141                                                next = strchrnul(line, '\n');
 142                                                free(sigc->signer);
 143                                                sigc->signer = xmemdupz(line, next - line);
 144                                        }
 145                                }
 146                                /* Do we have fingerprint? */
 147                                if (sigcheck_gpg_status[i].flags & GPG_STATUS_FINGERPRINT) {
 148                                        next = strchrnul(line, ' ');
 149                                        free(sigc->fingerprint);
 150                                        sigc->fingerprint = xmemdupz(line, next - line);
 151
 152                                        /* Skip interim fields */
 153                                        for (j = 9; j > 0; j--) {
 154                                                if (!*next)
 155                                                        break;
 156                                                line = next + 1;
 157                                                next = strchrnul(line, ' ');
 158                                        }
 159
 160                                        next = strchrnul(line, '\n');
 161                                        free(sigc->primary_key_fingerprint);
 162                                        sigc->primary_key_fingerprint = xmemdupz(line, next - line);
 163                                }
 164
 165                                break;
 166                        }
 167                }
 168        }
 169        return;
 170
 171found_duplicate_status:
 172        /*
 173         * GOODSIG, BADSIG etc. can occur only once for each signature.
 174         * Therefore, if we had more than one then we're dealing with multiple
 175         * signatures.  We don't support them currently, and they're rather
 176         * hard to create, so something is likely fishy and we should reject
 177         * them altogether.
 178         */
 179        sigc->result = 'E';
 180        /* Clear partial data to avoid confusion */
 181        FREE_AND_NULL(sigc->primary_key_fingerprint);
 182        FREE_AND_NULL(sigc->fingerprint);
 183        FREE_AND_NULL(sigc->signer);
 184        FREE_AND_NULL(sigc->key);
 185}
 186
 187int check_signature(const char *payload, size_t plen, const char *signature,
 188        size_t slen, struct signature_check *sigc)
 189{
 190        struct strbuf gpg_output = STRBUF_INIT;
 191        struct strbuf gpg_status = STRBUF_INIT;
 192        int status;
 193
 194        sigc->result = 'N';
 195
 196        status = verify_signed_buffer(payload, plen, signature, slen,
 197                                      &gpg_output, &gpg_status);
 198        if (status && !gpg_output.len)
 199                goto out;
 200        sigc->payload = xmemdupz(payload, plen);
 201        sigc->gpg_output = strbuf_detach(&gpg_output, NULL);
 202        sigc->gpg_status = strbuf_detach(&gpg_status, NULL);
 203        parse_gpg_output(sigc);
 204        status |= sigc->result != 'G' && sigc->result != 'U';
 205
 206 out:
 207        strbuf_release(&gpg_status);
 208        strbuf_release(&gpg_output);
 209
 210        return !!status;
 211}
 212
 213void print_signature_buffer(const struct signature_check *sigc, unsigned flags)
 214{
 215        const char *output = flags & GPG_VERIFY_RAW ?
 216                sigc->gpg_status : sigc->gpg_output;
 217
 218        if (flags & GPG_VERIFY_VERBOSE && sigc->payload)
 219                fputs(sigc->payload, stdout);
 220
 221        if (output)
 222                fputs(output, stderr);
 223}
 224
 225size_t parse_signature(const char *buf, size_t size)
 226{
 227        size_t len = 0;
 228        size_t match = size;
 229        while (len < size) {
 230                const char *eol;
 231
 232                if (get_format_by_sig(buf + len))
 233                        match = len;
 234
 235                eol = memchr(buf + len, '\n', size - len);
 236                len += eol ? eol - (buf + len) + 1 : size - len;
 237        }
 238        return match;
 239}
 240
 241void set_signing_key(const char *key)
 242{
 243        free(configured_signing_key);
 244        configured_signing_key = xstrdup(key);
 245}
 246
 247int git_gpg_config(const char *var, const char *value, void *cb)
 248{
 249        struct gpg_format *fmt = NULL;
 250        char *fmtname = NULL;
 251
 252        if (!strcmp(var, "user.signingkey")) {
 253                if (!value)
 254                        return config_error_nonbool(var);
 255                set_signing_key(value);
 256                return 0;
 257        }
 258
 259        if (!strcmp(var, "gpg.format")) {
 260                if (!value)
 261                        return config_error_nonbool(var);
 262                fmt = get_format_by_name(value);
 263                if (!fmt)
 264                        return error("unsupported value for %s: %s",
 265                                     var, value);
 266                use_format = fmt;
 267                return 0;
 268        }
 269
 270        if (!strcmp(var, "gpg.program") || !strcmp(var, "gpg.openpgp.program"))
 271                fmtname = "openpgp";
 272
 273        if (!strcmp(var, "gpg.x509.program"))
 274                fmtname = "x509";
 275
 276        if (fmtname) {
 277                fmt = get_format_by_name(fmtname);
 278                return git_config_string(&fmt->program, var, value);
 279        }
 280
 281        return 0;
 282}
 283
 284const char *get_signing_key(void)
 285{
 286        if (configured_signing_key)
 287                return configured_signing_key;
 288        return git_committer_info(IDENT_STRICT|IDENT_NO_DATE);
 289}
 290
 291int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key)
 292{
 293        struct child_process gpg = CHILD_PROCESS_INIT;
 294        int ret;
 295        size_t i, j, bottom;
 296        struct strbuf gpg_status = STRBUF_INIT;
 297
 298        argv_array_pushl(&gpg.args,
 299                         use_format->program,
 300                         "--status-fd=2",
 301                         "-bsau", signing_key,
 302                         NULL);
 303
 304        bottom = signature->len;
 305
 306        /*
 307         * When the username signingkey is bad, program could be terminated
 308         * because gpg exits without reading and then write gets SIGPIPE.
 309         */
 310        sigchain_push(SIGPIPE, SIG_IGN);
 311        ret = pipe_command(&gpg, buffer->buf, buffer->len,
 312                           signature, 1024, &gpg_status, 0);
 313        sigchain_pop(SIGPIPE);
 314
 315        ret |= !strstr(gpg_status.buf, "\n[GNUPG:] SIG_CREATED ");
 316        strbuf_release(&gpg_status);
 317        if (ret)
 318                return error(_("gpg failed to sign the data"));
 319
 320        /* Strip CR from the line endings, in case we are on Windows. */
 321        for (i = j = bottom; i < signature->len; i++)
 322                if (signature->buf[i] != '\r') {
 323                        if (i != j)
 324                                signature->buf[j] = signature->buf[i];
 325                        j++;
 326                }
 327        strbuf_setlen(signature, j);
 328
 329        return 0;
 330}
 331
 332int verify_signed_buffer(const char *payload, size_t payload_size,
 333                         const char *signature, size_t signature_size,
 334                         struct strbuf *gpg_output, struct strbuf *gpg_status)
 335{
 336        struct child_process gpg = CHILD_PROCESS_INIT;
 337        struct gpg_format *fmt;
 338        struct tempfile *temp;
 339        int ret;
 340        struct strbuf buf = STRBUF_INIT;
 341
 342        temp = mks_tempfile_t(".git_vtag_tmpXXXXXX");
 343        if (!temp)
 344                return error_errno(_("could not create temporary file"));
 345        if (write_in_full(temp->fd, signature, signature_size) < 0 ||
 346            close_tempfile_gently(temp) < 0) {
 347                error_errno(_("failed writing detached signature to '%s'"),
 348                            temp->filename.buf);
 349                delete_tempfile(&temp);
 350                return -1;
 351        }
 352
 353        fmt = get_format_by_sig(signature);
 354        if (!fmt)
 355                BUG("bad signature '%s'", signature);
 356
 357        argv_array_push(&gpg.args, fmt->program);
 358        argv_array_pushv(&gpg.args, fmt->verify_args);
 359        argv_array_pushl(&gpg.args,
 360                         "--status-fd=1",
 361                         "--verify", temp->filename.buf, "-",
 362                         NULL);
 363
 364        if (!gpg_status)
 365                gpg_status = &buf;
 366
 367        sigchain_push(SIGPIPE, SIG_IGN);
 368        ret = pipe_command(&gpg, payload, payload_size,
 369                           gpg_status, 0, gpg_output, 0);
 370        sigchain_pop(SIGPIPE);
 371
 372        delete_tempfile(&temp);
 373
 374        ret |= !strstr(gpg_status->buf, "\n[GNUPG:] GOODSIG ");
 375        strbuf_release(&buf); /* no matter it was used or not */
 376
 377        return ret;
 378}