gpg-interface.c

   1 #include "cache.h"
   2 #include "run-command.h"
   3 #include "strbuf.h"
   4 #include "gpg-interface.h"
   5 #include "sigchain.h"
   6
   7 static char *configured_signing_key;
   8 static const char *gpg_program = "gpg";
   9
  10 void signature_check_clear(struct signature_check *sigc)
  11 {
  12         free(sigc->payload);
  13         free(sigc->gpg_output);
  14         free(sigc->gpg_status);
  15         free(sigc->signer);
  16         free(sigc->key);
  17         sigc->payload = NULL;
  18         sigc->gpg_output = NULL;
  19         sigc->gpg_status = NULL;
  20         sigc->signer = NULL;
  21         sigc->key = NULL;
  22 }
  23
  24 void set_signing_key(const char *key)
  25 {
  26         free(configured_signing_key);
  27         configured_signing_key = xstrdup(key);
  28 }
  29
  30 int git_gpg_config(const char *var, const char *value, void *cb)
  31 {
  32         if (!strcmp(var, "user.signingkey")) {
  33                 set_signing_key(value);
  34         }
  35         if (!strcmp(var, "gpg.program")) {
  36                 if (!value)
  37                         return config_error_nonbool(var);
  38                 gpg_program = xstrdup(value);
  39         }
  40         return 0;
  41 }
  42
  43 const char *get_signing_key(void)
  44 {
  45         if (configured_signing_key)
  46                 return configured_signing_key;
  47         return git_committer_info(IDENT_STRICT|IDENT_NO_DATE);
  48 }
  49
  50 /*
  51  * Create a detached signature for the contents of "buffer" and append
  52  * it after "signature"; "buffer" and "signature" can be the same
  53  * strbuf instance, which would cause the detached signature appended
  54  * at the end.
  55  */
  56 int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key)
  57 {
  58         struct child_process gpg;
  59         const char *args[4];
  60         ssize_t len;
  61         size_t i, j, bottom;
  62
  63         memset(&gpg, 0, sizeof(gpg));
  64         gpg.argv = args;
  65         gpg.in = -1;
  66         gpg.out = -1;
  67         args[0] = gpg_program;
  68         args[1] = "-bsau";
  69         args[2] = signing_key;
  70         args[3] = NULL;
  71
  72         if (start_command(&gpg))
  73                 return error(_("could not run gpg."));
  74
  75         /*
  76          * When the username signingkey is bad, program could be terminated
  77          * because gpg exits without reading and then write gets SIGPIPE.
  78          */
  79         sigchain_push(SIGPIPE, SIG_IGN);
  80
  81         if (write_in_full(gpg.in, buffer->buf, buffer->len) != buffer->len) {
  82                 close(gpg.in);
  83                 close(gpg.out);
  84                 finish_command(&gpg);
  85                 return error(_("gpg did not accept the data"));
  86         }
  87         close(gpg.in);
  88
  89         bottom = signature->len;
  90         len = strbuf_read(signature, gpg.out, 1024);
  91         close(gpg.out);
  92
  93         sigchain_pop(SIGPIPE);
  94
  95         if (finish_command(&gpg) || !len || len < 0)
  96                 return error(_("gpg failed to sign the data"));
  97
  98         /* Strip CR from the line endings, in case we are on Windows. */
  99         for (i = j = bottom; i < signature->len; i++)
 100                 if (signature->buf[i] != '\r') {
 101                         if (i != j)
 102                                 signature->buf[j] = signature->buf[i];
 103                         j++;
 104                 }
 105         strbuf_setlen(signature, j);
 106
 107         return 0;
 108 }
 109
 110 /*
 111  * Run "gpg" to see if the payload matches the detached signature.
 112  * gpg_output, when set, receives the diagnostic output from GPG.
 113  * gpg_status, when set, receives the status output from GPG.
 114  */
 115 int verify_signed_buffer(const char *payload, size_t payload_size,
 116                          const char *signature, size_t signature_size,
 117                          struct strbuf *gpg_output, struct strbuf *gpg_status)
 118 {
 119         struct child_process gpg;
 120         const char *args_gpg[] = {NULL, "--status-fd=1", "--verify", "FILE", "-", NULL};
 121         char path[PATH_MAX];
 122         int fd, ret;
 123         struct strbuf buf = STRBUF_INIT;
 124         struct strbuf *pbuf = &buf;
 125
 126         args_gpg[0] = gpg_program;
 127         fd = git_mkstemp(path, PATH_MAX, ".git_vtag_tmpXXXXXX");
 128         if (fd < 0)
 129                 return error(_("could not create temporary file '%s': %s"),
 130                              path, strerror(errno));
 131         if (write_in_full(fd, signature, signature_size) < 0)
 132                 return error(_("failed writing detached signature to '%s': %s"),
 133                              path, strerror(errno));
 134         close(fd);
 135
 136         memset(&gpg, 0, sizeof(gpg));
 137         gpg.argv = args_gpg;
 138         gpg.in = -1;
 139         gpg.out = -1;
 140         if (gpg_output)
 141                 gpg.err = -1;
 142         args_gpg[3] = path;
 143         if (start_command(&gpg)) {
 144                 unlink(path);
 145                 return error(_("could not run gpg."));
 146         }
 147
 148         write_in_full(gpg.in, payload, payload_size);
 149         close(gpg.in);
 150
 151         if (gpg_output) {
 152                 strbuf_read(gpg_output, gpg.err, 0);
 153                 close(gpg.err);
 154         }
 155         if (gpg_status)
 156                 pbuf = gpg_status;
 157         strbuf_read(pbuf, gpg.out, 0);
 158         close(gpg.out);
 159
 160         ret = finish_command(&gpg);
 161
 162         unlink_or_warn(path);
 163
 164         ret |= !strstr(pbuf->buf, "\n[GNUPG:] GOODSIG ");
 165         strbuf_release(&buf); /* no matter it was used or not */
 166
 167         return ret;
 168 }