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