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