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
   9 void set_signing_key(const char *key)
  10 {
  11         free(configured_signing_key);
  12         configured_signing_key = xstrdup(key);
  13 }
  14
  15 int git_gpg_config(const char *var, const char *value, void *cb)
  16 {
  17         if (!strcmp(var, "user.signingkey")) {
  18                 if (!value)
  19                         return config_error_nonbool(var);
  20                 set_signing_key(value);
  21         }
  22         return 0;
  23 }
  24
  25 const char *get_signing_key(void)
  26 {
  27         if (configured_signing_key)
  28                 return configured_signing_key;
  29         return git_committer_info(IDENT_ERROR_ON_NO_NAME|IDENT_NO_DATE);
  30 }
  31
  32 /*
  33  * Create a detached signature for the contents of "buffer" and append
  34  * it after "signature"; "buffer" and "signature" can be the same
  35  * strbuf instance, which would cause the detached signature appended
  36  * at the end.
  37  */
  38 int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key)
  39 {
  40         struct child_process gpg;
  41         const char *args[4];
  42         ssize_t len;
  43         size_t i, j, bottom;
  44
  45         memset(&gpg, 0, sizeof(gpg));
  46         gpg.argv = args;
  47         gpg.in = -1;
  48         gpg.out = -1;
  49         args[0] = "gpg";
  50         args[1] = "-bsau";
  51         args[2] = signing_key;
  52         args[3] = NULL;
  53
  54         if (start_command(&gpg))
  55                 return error(_("could not run gpg."));
  56
  57         /*
  58          * When the username signingkey is bad, program could be terminated
  59          * because gpg exits without reading and then write gets SIGPIPE.
  60          */
  61         sigchain_push(SIGPIPE, SIG_IGN);
  62
  63         if (write_in_full(gpg.in, buffer->buf, buffer->len) != buffer->len) {
  64                 close(gpg.in);
  65                 close(gpg.out);
  66                 finish_command(&gpg);
  67                 return error(_("gpg did not accept the data"));
  68         }
  69         close(gpg.in);
  70
  71         bottom = signature->len;
  72         len = strbuf_read(signature, gpg.out, 1024);
  73         close(gpg.out);
  74
  75         sigchain_pop(SIGPIPE);
  76
  77         if (finish_command(&gpg) || !len || len < 0)
  78                 return error(_("gpg failed to sign the data"));
  79
  80         /* Strip CR from the line endings, in case we are on Windows. */
  81         for (i = j = bottom; i < signature->len; i++)
  82                 if (signature->buf[i] != '\r') {
  83                         if (i != j)
  84                                 signature->buf[j] = signature->buf[i];
  85                         j++;
  86                 }
  87         strbuf_setlen(signature, j);
  88
  89         return 0;
  90 }
  91
  92 /*
  93  * Run "gpg" to see if the payload matches the detached signature.
  94  * gpg_output_to tells where the output from "gpg" should go:
  95  *   < 0: /dev/null
  96  *   = 0: standard error of the calling process
  97  *   > 0: the specified file descriptor
  98  */
  99 int verify_signed_buffer(const char *payload, size_t payload_size,
 100                          const char *signature, size_t signature_size,
 101                          struct strbuf *gpg_output)
 102 {
 103         struct child_process gpg;
 104         const char *args_gpg[] = {"gpg", "--verify", "FILE", "-", NULL};
 105         char path[PATH_MAX];
 106         int fd, ret;
 107
 108         fd = git_mkstemp(path, PATH_MAX, ".git_vtag_tmpXXXXXX");
 109         if (fd < 0)
 110                 return error("could not create temporary file '%s': %s",
 111                              path, strerror(errno));
 112         if (write_in_full(fd, signature, signature_size) < 0)
 113                 return error("failed writing detached signature to '%s': %s",
 114                              path, strerror(errno));
 115         close(fd);
 116
 117         memset(&gpg, 0, sizeof(gpg));
 118         gpg.argv = args_gpg;
 119         gpg.in = -1;
 120         if (gpg_output)
 121                 gpg.err = -1;
 122         args_gpg[2] = path;
 123         if (start_command(&gpg)) {
 124                 unlink(path);
 125                 return error("could not run gpg.");
 126         }
 127
 128         write_in_full(gpg.in, payload, payload_size);
 129         close(gpg.in);
 130
 131         if (gpg_output)
 132                 strbuf_read(gpg_output, gpg.err, 0);
 133         ret = finish_command(&gpg);
 134
 135         unlink_or_warn(path);
 136
 137         return ret;
 138 }