git.oblomov.eu Git - git/blob - gpg-interface.c

   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
   9 static char *configured_signing_key;
  10 struct gpg_format {
  11         const char *name;
  12         const char *program;
  13         const char **verify_args;
  14         const char **sigs;
  15 };
  16
  17 static const char *openpgp_verify_args[] = {
  18         "--keyid-format=long",
  19         NULL
  20 };
  21 static const char *openpgp_sigs[] = {
  22         "-----BEGIN PGP SIGNATURE-----",
  23         "-----BEGIN PGP MESSAGE-----",
  24         NULL
  25 };
  26
  27 static const char *x509_verify_args[] = {
  28         NULL
  29 };
  30 static const char *x509_sigs[] = {
  31         "-----BEGIN SIGNED MESSAGE-----",
  32         NULL
  33 };
  34
  35 static 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
  46 static struct gpg_format *use_format = &gpg_format[0];
  47
  48 static 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
  58 static 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
  69 void 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
  81 static 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
  96 static 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
 140 found_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
 154 int 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
 180 void 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
 192 size_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
 208 void set_signing_key(const char *key)
 209 {
 210         free(configured_signing_key);
 211         configured_signing_key = xstrdup(key);
 212 }
 213
 214 int 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
 251 const 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
 258 int 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
 299 int 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 }