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 set_signing_key(const char *key)
  11 {
  12         free(configured_signing_key);
  13         configured_signing_key = xstrdup(key);
  14 }
  15
  16 int git_gpg_config(const char *var, const char *value, void *cb)
  17 {
  18         if (!strcmp(var, "user.signingkey")) {
  19                 set_signing_key(value);
  20         }
  21         if (!strcmp(var, "gpg.program")) {
  22                 if (!value)
  23                         return config_error_nonbool(var);
  24                 gpg_program = xstrdup(value);
  25         }
  26         return 0;
  27 }
  28
  29 const char *get_signing_key(void)
  30 {
  31         if (configured_signing_key)
  32                 return configured_signing_key;
  33         return git_committer_info(IDENT_STRICT|IDENT_NO_DATE);
  34 }
  35
  36 /*
  37  * Create a detached signature for the contents of "buffer" and append
  38  * it after "signature"; "buffer" and "signature" can be the same
  39  * strbuf instance, which would cause the detached signature appended
  40  * at the end.
  41  */
  42 int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key)
  43 {
  44         struct child_process gpg;
  45         const char *args[4];
  46         ssize_t len;
  47         size_t i, j, bottom;
  48
  49         memset(&gpg, 0, sizeof(gpg));
  50         gpg.argv = args;
  51         gpg.in = -1;
  52         gpg.out = -1;
  53         args[0] = gpg_program;
  54         args[1] = "-bsau";
  55         args[2] = signing_key;
  56         args[3] = NULL;
  57
  58         if (start_command(&gpg))
  59                 return error(_("could not run gpg."));
  60
  61         /*
  62          * When the username signingkey is bad, program could be terminated
  63          * because gpg exits without reading and then write gets SIGPIPE.
  64          */
  65         sigchain_push(SIGPIPE, SIG_IGN);
  66
  67         if (write_in_full(gpg.in, buffer->buf, buffer->len) != buffer->len) {
  68                 close(gpg.in);
  69                 close(gpg.out);
  70                 finish_command(&gpg);
  71                 return error(_("gpg did not accept the data"));
  72         }
  73         close(gpg.in);
  74
  75         bottom = signature->len;
  76         len = strbuf_read(signature, gpg.out, 1024);
  77         close(gpg.out);
  78
  79         sigchain_pop(SIGPIPE);
  80
  81         if (finish_command(&gpg) || !len || len < 0)
  82                 return error(_("gpg failed to sign the data"));
  83
  84         /* Strip CR from the line endings, in case we are on Windows. */
  85         for (i = j = bottom; i < signature->len; i++)
  86                 if (signature->buf[i] != '\r') {
  87                         if (i != j)
  88                                 signature->buf[j] = signature->buf[i];
  89                         j++;
  90                 }
  91         strbuf_setlen(signature, j);
  92
  93         return 0;
  94 }
  95
  96 /*
  97  * Run "gpg" to see if the payload matches the detached signature.
  98  * gpg_output, when set, receives the diagnostic output from GPG.
  99  */
 100 int verify_signed_buffer(const char *payload, size_t payload_size,
 101                          const char *signature, size_t signature_size,
 102                          struct strbuf *gpg_output)
 103 {
 104         struct child_process gpg;
 105         const char *args_gpg[] = {NULL, "--verify", "FILE", "-", NULL};
 106         char path[PATH_MAX];
 107         int fd, ret;
 108
 109         args_gpg[0] = gpg_program;
 110         fd = git_mkstemp(path, PATH_MAX, ".git_vtag_tmpXXXXXX");
 111         if (fd < 0)
 112                 return error("could not create temporary file '%s': %s",
 113                              path, strerror(errno));
 114         if (write_in_full(fd, signature, signature_size) < 0)
 115                 return error("failed writing detached signature to '%s': %s",
 116                              path, strerror(errno));
 117         close(fd);
 118
 119         memset(&gpg, 0, sizeof(gpg));
 120         gpg.argv = args_gpg;
 121         gpg.in = -1;
 122         if (gpg_output)
 123                 gpg.err = -1;
 124         args_gpg[2] = path;
 125         if (start_command(&gpg)) {
 126                 unlink(path);
 127                 return error("could not run gpg.");
 128         }
 129
 130         write_in_full(gpg.in, payload, payload_size);
 131         close(gpg.in);
 132
 133         if (gpg_output) {
 134                 strbuf_read(gpg_output, gpg.err, 0);
 135                 close(gpg.err);
 136         }
 137         ret = finish_command(&gpg);
 138
 139         unlink_or_warn(path);
 140
 141         return ret;
 142 }