Andrew's git - gitweb.git/blob

71618d86b9153a62b1b52b57fea1a5234d35b1f0
   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}
  77
  78/* An exclusive status -- only one of them can appear in output */
  79#define GPG_STATUS_EXCLUSIVE    (1<<0)
  80/* The status includes key identifier */
  81#define GPG_STATUS_KEYID        (1<<1)
  82/* The status includes user identifier */
  83#define GPG_STATUS_UID          (1<<2)
  84
  85/* Short-hand for standard exclusive *SIG status with keyid & UID */
  86#define GPG_STATUS_STDSIG       (GPG_STATUS_EXCLUSIVE|GPG_STATUS_KEYID|GPG_STATUS_UID)
  87
  88static struct {
  89        char result;
  90        const char *check;
  91        unsigned int flags;
  92} sigcheck_gpg_status[] = {
  93        { 'G', "GOODSIG ", GPG_STATUS_STDSIG },
  94        { 'B', "BADSIG ", GPG_STATUS_STDSIG },
  95        { 'U', "TRUST_NEVER", 0 },
  96        { 'U', "TRUST_UNDEFINED", 0 },
  97        { 'E', "ERRSIG ", GPG_STATUS_EXCLUSIVE|GPG_STATUS_KEYID },
  98        { 'X', "EXPSIG ", GPG_STATUS_STDSIG },
  99        { 'Y', "EXPKEYSIG ", GPG_STATUS_STDSIG },
 100        { 'R', "REVKEYSIG ", GPG_STATUS_STDSIG },
 101};
 102
 103static void parse_gpg_output(struct signature_check *sigc)
 104{
 105        const char *buf = sigc->gpg_status;
 106        const char *line, *next;
 107        int i;
 108        int seen_exclusive_status = 0;
 109
 110        /* Iterate over all lines */
 111        for (line = buf; *line; line = strchrnul(line+1, '\n')) {
 112                while (*line == '\n')
 113                        line++;
 114                /* Skip lines that don't start with GNUPG status */
 115                if (!skip_prefix(line, "[GNUPG:] ", &line))
 116                        continue;
 117
 118                /* Iterate over all search strings */
 119                for (i = 0; i < ARRAY_SIZE(sigcheck_gpg_status); i++) {
 120                        if (skip_prefix(line, sigcheck_gpg_status[i].check, &line)) {
 121                                if (sigcheck_gpg_status[i].flags & GPG_STATUS_EXCLUSIVE) {
 122                                        if (++seen_exclusive_status > 1)
 123                                                goto found_duplicate_status;
 124                                }
 125
 126                                sigc->result = sigcheck_gpg_status[i].result;
 127                                /* Do we have key information? */
 128                                if (sigcheck_gpg_status[i].flags & GPG_STATUS_KEYID) {
 129                                        next = strchrnul(line, ' ');
 130                                        free(sigc->key);
 131                                        sigc->key = xmemdupz(line, next - line);
 132                                        /* Do we have signer information? */
 133                                        if (*next && (sigcheck_gpg_status[i].flags & GPG_STATUS_UID)) {
 134                                                line = next + 1;
 135                                                next = strchrnul(line, '\n');
 136                                                free(sigc->signer);
 137                                                sigc->signer = xmemdupz(line, next - line);
 138                                        }
 139                                }
 140
 141                                break;
 142                        }
 143                }
 144        }
 145        return;
 146
 147found_duplicate_status:
 148        /*
 149         * GOODSIG, BADSIG etc. can occur only once for each signature.
 150         * Therefore, if we had more than one then we're dealing with multiple
 151         * signatures.  We don't support them currently, and they're rather
 152         * hard to create, so something is likely fishy and we should reject
 153         * them altogether.
 154         */
 155        sigc->result = 'E';
 156        /* Clear partial data to avoid confusion */
 157        FREE_AND_NULL(sigc->signer);
 158        FREE_AND_NULL(sigc->key);
 159}
 160
 161int check_signature(const char *payload, size_t plen, const char *signature,
 162        size_t slen, struct signature_check *sigc)
 163{
 164        struct strbuf gpg_output = STRBUF_INIT;
 165        struct strbuf gpg_status = STRBUF_INIT;
 166        int status;
 167
 168        sigc->result = 'N';
 169
 170        status = verify_signed_buffer(payload, plen, signature, slen,
 171                                      &gpg_output, &gpg_status);
 172        if (status && !gpg_output.len)
 173                goto out;
 174        sigc->payload = xmemdupz(payload, plen);
 175        sigc->gpg_output = strbuf_detach(&gpg_output, NULL);
 176        sigc->gpg_status = strbuf_detach(&gpg_status, NULL);
 177        parse_gpg_output(sigc);
 178        status |= sigc->result != 'G' && sigc->result != 'U';
 179
 180 out:
 181        strbuf_release(&gpg_status);
 182        strbuf_release(&gpg_output);
 183
 184        return !!status;
 185}
 186
 187void print_signature_buffer(const struct signature_check *sigc, unsigned flags)
 188{
 189        const char *output = flags & GPG_VERIFY_RAW ?
 190                sigc->gpg_status : sigc->gpg_output;
 191
 192        if (flags & GPG_VERIFY_VERBOSE && sigc->payload)
 193                fputs(sigc->payload, stdout);
 194
 195        if (output)
 196                fputs(output, stderr);
 197}
 198
 199size_t parse_signature(const char *buf, size_t size)
 200{
 201        size_t len = 0;
 202        size_t match = size;
 203        while (len < size) {
 204                const char *eol;
 205
 206                if (get_format_by_sig(buf + len))
 207                        match = len;
 208
 209                eol = memchr(buf + len, '\n', size - len);
 210                len += eol ? eol - (buf + len) + 1 : size - len;
 211        }
 212        return match;
 213}
 214
 215void set_signing_key(const char *key)
 216{
 217        free(configured_signing_key);
 218        configured_signing_key = xstrdup(key);
 219}
 220
 221int git_gpg_config(const char *var, const char *value, void *cb)
 222{
 223        struct gpg_format *fmt = NULL;
 224        char *fmtname = NULL;
 225
 226        if (!strcmp(var, "user.signingkey")) {
 227                if (!value)
 228                        return config_error_nonbool(var);
 229                set_signing_key(value);
 230                return 0;
 231        }
 232
 233        if (!strcmp(var, "gpg.format")) {
 234                if (!value)
 235                        return config_error_nonbool(var);
 236                fmt = get_format_by_name(value);
 237                if (!fmt)
 238                        return error("unsupported value for %s: %s",
 239                                     var, value);
 240                use_format = fmt;
 241                return 0;
 242        }
 243
 244        if (!strcmp(var, "gpg.program") || !strcmp(var, "gpg.openpgp.program"))
 245                fmtname = "openpgp";
 246
 247        if (!strcmp(var, "gpg.x509.program"))
 248                fmtname = "x509";
 249
 250        if (fmtname) {
 251                fmt = get_format_by_name(fmtname);
 252                return git_config_string(&fmt->program, var, value);
 253        }
 254
 255        return 0;
 256}
 257
 258const char *get_signing_key(void)
 259{
 260        if (configured_signing_key)
 261                return configured_signing_key;
 262        return git_committer_info(IDENT_STRICT|IDENT_NO_DATE);
 263}
 264
 265int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key)
 266{
 267        struct child_process gpg = CHILD_PROCESS_INIT;
 268        int ret;
 269        size_t i, j, bottom;
 270        struct strbuf gpg_status = STRBUF_INIT;
 271
 272        argv_array_pushl(&gpg.args,
 273                         use_format->program,
 274                         "--status-fd=2",
 275                         "-bsau", signing_key,
 276                         NULL);
 277
 278        bottom = signature->len;
 279
 280        /*
 281         * When the username signingkey is bad, program could be terminated
 282         * because gpg exits without reading and then write gets SIGPIPE.
 283         */
 284        sigchain_push(SIGPIPE, SIG_IGN);
 285        ret = pipe_command(&gpg, buffer->buf, buffer->len,
 286                           signature, 1024, &gpg_status, 0);
 287        sigchain_pop(SIGPIPE);
 288
 289        ret |= !strstr(gpg_status.buf, "\n[GNUPG:] SIG_CREATED ");
 290        strbuf_release(&gpg_status);
 291        if (ret)
 292                return error(_("gpg failed to sign the data"));
 293
 294        /* Strip CR from the line endings, in case we are on Windows. */
 295        for (i = j = bottom; i < signature->len; i++)
 296                if (signature->buf[i] != '\r') {
 297                        if (i != j)
 298                                signature->buf[j] = signature->buf[i];
 299                        j++;
 300                }
 301        strbuf_setlen(signature, j);
 302
 303        return 0;
 304}
 305
 306int verify_signed_buffer(const char *payload, size_t payload_size,
 307                         const char *signature, size_t signature_size,
 308                         struct strbuf *gpg_output, struct strbuf *gpg_status)
 309{
 310        struct child_process gpg = CHILD_PROCESS_INIT;
 311        struct gpg_format *fmt;
 312        struct tempfile *temp;
 313        int ret;
 314        struct strbuf buf = STRBUF_INIT;
 315
 316        temp = mks_tempfile_t(".git_vtag_tmpXXXXXX");
 317        if (!temp)
 318                return error_errno(_("could not create temporary file"));
 319        if (write_in_full(temp->fd, signature, signature_size) < 0 ||
 320            close_tempfile_gently(temp) < 0) {
 321                error_errno(_("failed writing detached signature to '%s'"),
 322                            temp->filename.buf);
 323                delete_tempfile(&temp);
 324                return -1;
 325        }
 326
 327        fmt = get_format_by_sig(signature);
 328        if (!fmt)
 329                BUG("bad signature '%s'", signature);
 330
 331        argv_array_push(&gpg.args, fmt->program);
 332        argv_array_pushv(&gpg.args, fmt->verify_args);
 333        argv_array_pushl(&gpg.args,
 334                         "--status-fd=1",
 335                         "--verify", temp->filename.buf, "-",
 336                         NULL);
 337
 338        if (!gpg_status)
 339                gpg_status = &buf;
 340
 341        sigchain_push(SIGPIPE, SIG_IGN);
 342        ret = pipe_command(&gpg, payload, payload_size,
 343                           gpg_status, 0, gpg_output, 0);
 344        sigchain_pop(SIGPIPE);
 345
 346        delete_tempfile(&temp);
 347
 348        ret |= !strstr(gpg_status->buf, "\n[GNUPG:] GOODSIG ");
 349        strbuf_release(&buf); /* no matter it was used or not */
 350
 351        return ret;
 352}