Andrew's git - gitweb.git/blob

efe2c0d3863c7b4118d08c4152dbc6e1d5dcc09f
   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
  81static struct {
  82        char result;
  83        const char *check;
  84        unsigned int flags;
  85} sigcheck_gpg_status[] = {
  86        { 'G', "GOODSIG ", GPG_STATUS_EXCLUSIVE },
  87        { 'B', "BADSIG ", GPG_STATUS_EXCLUSIVE },
  88        { 'U', "TRUST_NEVER", 0 },
  89        { 'U', "TRUST_UNDEFINED", 0 },
  90        { 'E', "ERRSIG ", GPG_STATUS_EXCLUSIVE },
  91        { 'X', "EXPSIG ", GPG_STATUS_EXCLUSIVE },
  92        { 'Y', "EXPKEYSIG ", GPG_STATUS_EXCLUSIVE },
  93        { 'R', "REVKEYSIG ", GPG_STATUS_EXCLUSIVE },
  94};
  95
  96static void parse_gpg_output(struct signature_check *sigc)
  97{
  98        const char *buf = sigc->gpg_status;
  99        const char *line, *next;
 100        int i;
 101        int seen_exclusive_status = 0;
 102
 103        /* Iterate over all lines */
 104        for (line = buf; *line; line = strchrnul(line+1, '\n')) {
 105                while (*line == '\n')
 106                        line++;
 107                /* Skip lines that don't start with GNUPG status */
 108                if (!skip_prefix(line, "[GNUPG:] ", &line))
 109                        continue;
 110
 111                /* Iterate over all search strings */
 112                for (i = 0; i < ARRAY_SIZE(sigcheck_gpg_status); i++) {
 113                        if (skip_prefix(line, sigcheck_gpg_status[i].check, &line)) {
 114                                if (sigcheck_gpg_status[i].flags & GPG_STATUS_EXCLUSIVE) {
 115                                        if (++seen_exclusive_status > 1)
 116                                                goto found_duplicate_status;
 117                                }
 118
 119                                sigc->result = sigcheck_gpg_status[i].result;
 120                                /* The trust messages are not followed by key/signer information */
 121                                if (sigc->result != 'U') {
 122                                        next = strchrnul(line, ' ');
 123                                        free(sigc->key);
 124                                        sigc->key = xmemdupz(line, next - line);
 125                                        /* The ERRSIG message is not followed by signer information */
 126                                        if (*next && sigc->result != 'E') {
 127                                                line = next + 1;
 128                                                next = strchrnul(line, '\n');
 129                                                free(sigc->signer);
 130                                                sigc->signer = xmemdupz(line, next - line);
 131                                        }
 132                                }
 133
 134                                break;
 135                        }
 136                }
 137        }
 138        return;
 139
 140found_duplicate_status:
 141        /*
 142         * GOODSIG, BADSIG etc. can occur only once for each signature.
 143         * Therefore, if we had more than one then we're dealing with multiple
 144         * signatures.  We don't support them currently, and they're rather
 145         * hard to create, so something is likely fishy and we should reject
 146         * them altogether.
 147         */
 148        sigc->result = 'E';
 149        /* Clear partial data to avoid confusion */
 150        FREE_AND_NULL(sigc->signer);
 151        FREE_AND_NULL(sigc->key);
 152}
 153
 154int check_signature(const char *payload, size_t plen, const char *signature,
 155        size_t slen, struct signature_check *sigc)
 156{
 157        struct strbuf gpg_output = STRBUF_INIT;
 158        struct strbuf gpg_status = STRBUF_INIT;
 159        int status;
 160
 161        sigc->result = 'N';
 162
 163        status = verify_signed_buffer(payload, plen, signature, slen,
 164                                      &gpg_output, &gpg_status);
 165        if (status && !gpg_output.len)
 166                goto out;
 167        sigc->payload = xmemdupz(payload, plen);
 168        sigc->gpg_output = strbuf_detach(&gpg_output, NULL);
 169        sigc->gpg_status = strbuf_detach(&gpg_status, NULL);
 170        parse_gpg_output(sigc);
 171        status |= sigc->result != 'G' && sigc->result != 'U';
 172
 173 out:
 174        strbuf_release(&gpg_status);
 175        strbuf_release(&gpg_output);
 176
 177        return !!status;
 178}
 179
 180void print_signature_buffer(const struct signature_check *sigc, unsigned flags)
 181{
 182        const char *output = flags & GPG_VERIFY_RAW ?
 183                sigc->gpg_status : sigc->gpg_output;
 184
 185        if (flags & GPG_VERIFY_VERBOSE && sigc->payload)
 186                fputs(sigc->payload, stdout);
 187
 188        if (output)
 189                fputs(output, stderr);
 190}
 191
 192size_t parse_signature(const char *buf, size_t size)
 193{
 194        size_t len = 0;
 195        size_t match = size;
 196        while (len < size) {
 197                const char *eol;
 198
 199                if (get_format_by_sig(buf + len))
 200                        match = len;
 201
 202                eol = memchr(buf + len, '\n', size - len);
 203                len += eol ? eol - (buf + len) + 1 : size - len;
 204        }
 205        return match;
 206}
 207
 208void set_signing_key(const char *key)
 209{
 210        free(configured_signing_key);
 211        configured_signing_key = xstrdup(key);
 212}
 213
 214int git_gpg_config(const char *var, const char *value, void *cb)
 215{
 216        struct gpg_format *fmt = NULL;
 217        char *fmtname = NULL;
 218
 219        if (!strcmp(var, "user.signingkey")) {
 220                if (!value)
 221                        return config_error_nonbool(var);
 222                set_signing_key(value);
 223                return 0;
 224        }
 225
 226        if (!strcmp(var, "gpg.format")) {
 227                if (!value)
 228                        return config_error_nonbool(var);
 229                fmt = get_format_by_name(value);
 230                if (!fmt)
 231                        return error("unsupported value for %s: %s",
 232                                     var, value);
 233                use_format = fmt;
 234                return 0;
 235        }
 236
 237        if (!strcmp(var, "gpg.program") || !strcmp(var, "gpg.openpgp.program"))
 238                fmtname = "openpgp";
 239
 240        if (!strcmp(var, "gpg.x509.program"))
 241                fmtname = "x509";
 242
 243        if (fmtname) {
 244                fmt = get_format_by_name(fmtname);
 245                return git_config_string(&fmt->program, var, value);
 246        }
 247
 248        return 0;
 249}
 250
 251const char *get_signing_key(void)
 252{
 253        if (configured_signing_key)
 254                return configured_signing_key;
 255        return git_committer_info(IDENT_STRICT|IDENT_NO_DATE);
 256}
 257
 258int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key)
 259{
 260        struct child_process gpg = CHILD_PROCESS_INIT;
 261        int ret;
 262        size_t i, j, bottom;
 263        struct strbuf gpg_status = STRBUF_INIT;
 264
 265        argv_array_pushl(&gpg.args,
 266                         use_format->program,
 267                         "--status-fd=2",
 268                         "-bsau", signing_key,
 269                         NULL);
 270
 271        bottom = signature->len;
 272
 273        /*
 274         * When the username signingkey is bad, program could be terminated
 275         * because gpg exits without reading and then write gets SIGPIPE.
 276         */
 277        sigchain_push(SIGPIPE, SIG_IGN);
 278        ret = pipe_command(&gpg, buffer->buf, buffer->len,
 279                           signature, 1024, &gpg_status, 0);
 280        sigchain_pop(SIGPIPE);
 281
 282        ret |= !strstr(gpg_status.buf, "\n[GNUPG:] SIG_CREATED ");
 283        strbuf_release(&gpg_status);
 284        if (ret)
 285                return error(_("gpg failed to sign the data"));
 286
 287        /* Strip CR from the line endings, in case we are on Windows. */
 288        for (i = j = bottom; i < signature->len; i++)
 289                if (signature->buf[i] != '\r') {
 290                        if (i != j)
 291                                signature->buf[j] = signature->buf[i];
 292                        j++;
 293                }
 294        strbuf_setlen(signature, j);
 295
 296        return 0;
 297}
 298
 299int verify_signed_buffer(const char *payload, size_t payload_size,
 300                         const char *signature, size_t signature_size,
 301                         struct strbuf *gpg_output, struct strbuf *gpg_status)
 302{
 303        struct child_process gpg = CHILD_PROCESS_INIT;
 304        struct gpg_format *fmt;
 305        struct tempfile *temp;
 306        int ret;
 307        struct strbuf buf = STRBUF_INIT;
 308
 309        temp = mks_tempfile_t(".git_vtag_tmpXXXXXX");
 310        if (!temp)
 311                return error_errno(_("could not create temporary file"));
 312        if (write_in_full(temp->fd, signature, signature_size) < 0 ||
 313            close_tempfile_gently(temp) < 0) {
 314                error_errno(_("failed writing detached signature to '%s'"),
 315                            temp->filename.buf);
 316                delete_tempfile(&temp);
 317                return -1;
 318        }
 319
 320        fmt = get_format_by_sig(signature);
 321        if (!fmt)
 322                BUG("bad signature '%s'", signature);
 323
 324        argv_array_push(&gpg.args, fmt->program);
 325        argv_array_pushv(&gpg.args, fmt->verify_args);
 326        argv_array_pushl(&gpg.args,
 327                         "--status-fd=1",
 328                         "--verify", temp->filename.buf, "-",
 329                         NULL);
 330
 331        if (!gpg_status)
 332                gpg_status = &buf;
 333
 334        sigchain_push(SIGPIPE, SIG_IGN);
 335        ret = pipe_command(&gpg, payload, payload_size,
 336                           gpg_status, 0, gpg_output, 0);
 337        sigchain_pop(SIGPIPE);
 338
 339        delete_tempfile(&temp);
 340
 341        ret |= !strstr(gpg_status->buf, "\n[GNUPG:] GOODSIG ");
 342        strbuf_release(&buf); /* no matter it was used or not */
 343
 344        return ret;
 345}