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 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 size_t parse_signature(const char *buf, unsigned long size)
 105 {
 106         char *eol;
 107         size_t len = 0;
 108         while (len < size && !starts_with(buf + len, PGP_SIGNATURE) &&
 109                         !starts_with(buf + len, PGP_MESSAGE)) {
 110                 eol = memchr(buf + len, '\n', size - len);
 111                 len += eol ? eol - (buf + len) + 1 : size - len;
 112         }
 113         return len;
 114 }
 115
 116 void set_signing_key(const char *key)
 117 {
 118         free(configured_signing_key);
 119         configured_signing_key = xstrdup(key);
 120 }
 121
 122 int git_gpg_config(const char *var, const char *value, void *cb)
 123 {
 124         if (!strcmp(var, "user.signingkey")) {
 125                 if (!value)
 126                         return config_error_nonbool(var);
 127                 set_signing_key(value);
 128                 return 0;
 129         }
 130
 131         if (!strcmp(var, "gpg.program")) {
 132                 if (!value)
 133                         return config_error_nonbool(var);
 134                 gpg_program = xstrdup(value);
 135                 return 0;
 136         }
 137
 138         return 0;
 139 }
 140
 141 const char *get_signing_key(void)
 142 {
 143         if (configured_signing_key)
 144                 return configured_signing_key;
 145         return git_committer_info(IDENT_STRICT|IDENT_NO_DATE);
 146 }
 147
 148 int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key)
 149 {
 150         struct child_process gpg = CHILD_PROCESS_INIT;
 151         int ret;
 152         size_t i, j, bottom;
 153         struct strbuf gpg_status = STRBUF_INIT;
 154
 155         argv_array_pushl(&gpg.args,
 156                          gpg_program,
 157                          "--status-fd=2",
 158                          "-bsau", signing_key,
 159                          NULL);
 160
 161         bottom = signature->len;
 162
 163         /*
 164          * When the username signingkey is bad, program could be terminated
 165          * because gpg exits without reading and then write gets SIGPIPE.
 166          */
 167         sigchain_push(SIGPIPE, SIG_IGN);
 168         ret = pipe_command(&gpg, buffer->buf, buffer->len,
 169                            signature, 1024, &gpg_status, 0);
 170         sigchain_pop(SIGPIPE);
 171
 172         ret |= !strstr(gpg_status.buf, "\n[GNUPG:] SIG_CREATED ");
 173         strbuf_release(&gpg_status);
 174         if (ret)
 175                 return error(_("gpg failed to sign the data"));
 176
 177         /* Strip CR from the line endings, in case we are on Windows. */
 178         for (i = j = bottom; i < signature->len; i++)
 179                 if (signature->buf[i] != '\r') {
 180                         if (i != j)
 181                                 signature->buf[j] = signature->buf[i];
 182                         j++;
 183                 }
 184         strbuf_setlen(signature, j);
 185
 186         return 0;
 187 }
 188
 189 int verify_signed_buffer(const char *payload, size_t payload_size,
 190                          const char *signature, size_t signature_size,
 191                          struct strbuf *gpg_output, struct strbuf *gpg_status)
 192 {
 193         struct child_process gpg = CHILD_PROCESS_INIT;
 194         struct tempfile *temp;
 195         int ret;
 196         struct strbuf buf = STRBUF_INIT;
 197
 198         temp = mks_tempfile_t(".git_vtag_tmpXXXXXX");
 199         if (!temp)
 200                 return error_errno(_("could not create temporary file"));
 201         if (write_in_full(temp->fd, signature, signature_size) < 0 ||
 202             close_tempfile_gently(temp) < 0) {
 203                 error_errno(_("failed writing detached signature to '%s'"),
 204                             temp->filename.buf);
 205                 delete_tempfile(&temp);
 206                 return -1;
 207         }
 208
 209         argv_array_pushl(&gpg.args,
 210                          gpg_program,
 211                          "--status-fd=1",
 212                          "--keyid-format=long",
 213                          "--verify", temp->filename.buf, "-",
 214                          NULL);
 215
 216         if (!gpg_status)
 217                 gpg_status = &buf;
 218
 219         sigchain_push(SIGPIPE, SIG_IGN);
 220         ret = pipe_command(&gpg, payload, payload_size,
 221                            gpg_status, 0, gpg_output, 0);
 222         sigchain_pop(SIGPIPE);
 223
 224         delete_tempfile(&temp);
 225
 226         ret |= !strstr(gpg_status->buf, "\n[GNUPG:] GOODSIG ");
 227         strbuf_release(&buf); /* no matter it was used or not */
 228
 229         return ret;
 230 }