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 /* 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
  88 static 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
 103 static 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
 147 found_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
 161 int 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
 187 void 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
 199 size_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
 215 void set_signing_key(const char *key)
 216 {
 217         free(configured_signing_key);
 218         configured_signing_key = xstrdup(key);
 219 }
 220
 221 int 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
 258 const 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
 265 int 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
 306 int 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 }