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 static const char *gpg_program = "gpg";
  11
  12 #define PGP_SIGNATURE "-----BEGIN PGP SIGNATURE-----"
  13 #define PGP_MESSAGE "-----BEGIN PGP MESSAGE-----"
  14
  15 void signature_check_clear(struct signature_check *sigc)
  16 {
  17         FREE_AND_NULL(sigc->payload);
  18         FREE_AND_NULL(sigc->gpg_output);
  19         FREE_AND_NULL(sigc->gpg_status);
  20         FREE_AND_NULL(sigc->signer);
  21         FREE_AND_NULL(sigc->key);
  22 }
  23
  24 static struct {
  25         char result;
  26         const char *check;
  27 } sigcheck_gpg_status[] = {
  28         { 'G', "\n[GNUPG:] GOODSIG " },
  29         { 'B', "\n[GNUPG:] BADSIG " },
  30         { 'U', "\n[GNUPG:] TRUST_NEVER" },
  31         { 'U', "\n[GNUPG:] TRUST_UNDEFINED" },
  32         { 'E', "\n[GNUPG:] ERRSIG "},
  33         { 'X', "\n[GNUPG:] EXPSIG "},
  34         { 'Y', "\n[GNUPG:] EXPKEYSIG "},
  35         { 'R', "\n[GNUPG:] REVKEYSIG "},
  36 };
  37
  38 static void parse_gpg_output(struct signature_check *sigc)
  39 {
  40         const char *buf = sigc->gpg_status;
  41         int i;
  42
  43         /* Iterate over all search strings */
  44         for (i = 0; i < ARRAY_SIZE(sigcheck_gpg_status); i++) {
  45                 const char *found, *next;
  46
  47                 if (!skip_prefix(buf, sigcheck_gpg_status[i].check + 1, &found)) {
  48                         found = strstr(buf, sigcheck_gpg_status[i].check);
  49                         if (!found)
  50                                 continue;
  51                         found += strlen(sigcheck_gpg_status[i].check);
  52                 }
  53                 sigc->result = sigcheck_gpg_status[i].result;
  54                 /* The trust messages are not followed by key/signer information */
  55                 if (sigc->result != 'U') {
  56                         sigc->key = xmemdupz(found, 16);
  57                         /* The ERRSIG message is not followed by signer information */
  58                         if (sigc-> result != 'E') {
  59                                 found += 17;
  60                                 next = strchrnul(found, '\n');
  61                                 sigc->signer = xmemdupz(found, next - found);
  62                         }
  63                 }
  64         }
  65 }
  66
  67 int check_signature(const char *payload, size_t plen, const char *signature,
  68         size_t slen, struct signature_check *sigc)
  69 {
  70         struct strbuf gpg_output = STRBUF_INIT;
  71         struct strbuf gpg_status = STRBUF_INIT;
  72         int status;
  73
  74         sigc->result = 'N';
  75
  76         status = verify_signed_buffer(payload, plen, signature, slen,
  77                                       &gpg_output, &gpg_status);
  78         if (status && !gpg_output.len)
  79                 goto out;
  80         sigc->payload = xmemdupz(payload, plen);
  81         sigc->gpg_output = strbuf_detach(&gpg_output, NULL);
  82         sigc->gpg_status = strbuf_detach(&gpg_status, NULL);
  83         parse_gpg_output(sigc);
  84
  85  out:
  86         strbuf_release(&gpg_status);
  87         strbuf_release(&gpg_output);
  88
  89         return sigc->result != 'G' && sigc->result != 'U';
  90 }
  91
  92 void print_signature_buffer(const struct signature_check *sigc, unsigned flags)
  93 {
  94         const char *output = flags & GPG_VERIFY_RAW ?
  95                 sigc->gpg_status : sigc->gpg_output;
  96
  97         if (flags & GPG_VERIFY_VERBOSE && sigc->payload)
  98                 fputs(sigc->payload, stdout);
  99
 100         if (output)
 101                 fputs(output, stderr);
 102 }
 103
 104 static int is_gpg_start(const char *line)
 105 {
 106         return starts_with(line, PGP_SIGNATURE) ||
 107                 starts_with(line, PGP_MESSAGE);
 108 }
 109
 110 size_t parse_signature(const char *buf, size_t size)
 111 {
 112         size_t len = 0;
 113         size_t match = size;
 114         while (len < size) {
 115                 const char *eol;
 116
 117                 if (is_gpg_start(buf + len))
 118                         match = len;
 119
 120                 eol = memchr(buf + len, '\n', size - len);
 121                 len += eol ? eol - (buf + len) + 1 : size - len;
 122         }
 123         return match;
 124 }
 125
 126 void set_signing_key(const char *key)
 127 {
 128         free(configured_signing_key);
 129         configured_signing_key = xstrdup(key);
 130 }
 131
 132 int git_gpg_config(const char *var, const char *value, void *cb)
 133 {
 134         if (!strcmp(var, "user.signingkey")) {
 135                 if (!value)
 136                         return config_error_nonbool(var);
 137                 set_signing_key(value);
 138                 return 0;
 139         }
 140
 141         if (!strcmp(var, "gpg.program")) {
 142                 if (!value)
 143                         return config_error_nonbool(var);
 144                 gpg_program = xstrdup(value);
 145                 return 0;
 146         }
 147
 148         return 0;
 149 }
 150
 151 const char *get_signing_key(void)
 152 {
 153         if (configured_signing_key)
 154                 return configured_signing_key;
 155         return git_committer_info(IDENT_STRICT|IDENT_NO_DATE);
 156 }
 157
 158 int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key)
 159 {
 160         struct child_process gpg = CHILD_PROCESS_INIT;
 161         int ret;
 162         size_t i, j, bottom;
 163         struct strbuf gpg_status = STRBUF_INIT;
 164
 165         argv_array_pushl(&gpg.args,
 166                          gpg_program,
 167                          "--status-fd=2",
 168                          "-bsau", signing_key,
 169                          NULL);
 170
 171         bottom = signature->len;
 172
 173         /*
 174          * When the username signingkey is bad, program could be terminated
 175          * because gpg exits without reading and then write gets SIGPIPE.
 176          */
 177         sigchain_push(SIGPIPE, SIG_IGN);
 178         ret = pipe_command(&gpg, buffer->buf, buffer->len,
 179                            signature, 1024, &gpg_status, 0);
 180         sigchain_pop(SIGPIPE);
 181
 182         ret |= !strstr(gpg_status.buf, "\n[GNUPG:] SIG_CREATED ");
 183         strbuf_release(&gpg_status);
 184         if (ret)
 185                 return error(_("gpg failed to sign the data"));
 186
 187         /* Strip CR from the line endings, in case we are on Windows. */
 188         for (i = j = bottom; i < signature->len; i++)
 189                 if (signature->buf[i] != '\r') {
 190                         if (i != j)
 191                                 signature->buf[j] = signature->buf[i];
 192                         j++;
 193                 }
 194         strbuf_setlen(signature, j);
 195
 196         return 0;
 197 }
 198
 199 int verify_signed_buffer(const char *payload, size_t payload_size,
 200                          const char *signature, size_t signature_size,
 201                          struct strbuf *gpg_output, struct strbuf *gpg_status)
 202 {
 203         struct child_process gpg = CHILD_PROCESS_INIT;
 204         struct tempfile *temp;
 205         int ret;
 206         struct strbuf buf = STRBUF_INIT;
 207
 208         temp = mks_tempfile_t(".git_vtag_tmpXXXXXX");
 209         if (!temp)
 210                 return error_errno(_("could not create temporary file"));
 211         if (write_in_full(temp->fd, signature, signature_size) < 0 ||
 212             close_tempfile_gently(temp) < 0) {
 213                 error_errno(_("failed writing detached signature to '%s'"),
 214                             temp->filename.buf);
 215                 delete_tempfile(&temp);
 216                 return -1;
 217         }
 218
 219         argv_array_pushl(&gpg.args,
 220                          gpg_program,
 221                          "--status-fd=1",
 222                          "--keyid-format=long",
 223                          "--verify", temp->filename.buf, "-",
 224                          NULL);
 225
 226         if (!gpg_status)
 227                 gpg_status = &buf;
 228
 229         sigchain_push(SIGPIPE, SIG_IGN);
 230         ret = pipe_command(&gpg, payload, payload_size,
 231                            gpg_status, 0, gpg_output, 0);
 232         sigchain_pop(SIGPIPE);
 233
 234         delete_tempfile(&temp);
 235
 236         ret |= !strstr(gpg_status->buf, "\n[GNUPG:] GOODSIG ");
 237         strbuf_release(&buf); /* no matter it was used or not */
 238
 239         return ret;
 240 }