usign-exec.c

   1 /*
   2  * wrapper functions around the usign executable
   3  * Copyright (C) 2018 Daniel Golle <daniel@makrotopia.org>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 3
   7  * as published by the Free Software Foundation
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14
  15 #include <stdbool.h>
  16 #include <stdio.h>
  17 #include <string.h>
  18 #include <unistd.h>
  19 #include <sys/wait.h>
  20
  21 #include "usign.h"
  22
  23 #ifdef UCERT_HOST_BUILD
  24 #define USIGN_EXEC "usign"
  25 #else
  26 #define USIGN_EXEC "/usr/bin/usign"
  27 #endif
  28
  29 /*
  30  * check for revoker deadlink in pubkeydir
  31  * return true if a revoker exists, false otherwise
  32  */
  33 int _usign_key_is_revoked(const char *fingerprint, const char *pubkeydir) {
  34         char tml[64] = {0};
  35         char rfname[256] = {0};
  36
  37         snprintf(rfname, sizeof(rfname)-1, "%s/%s", pubkeydir, fingerprint);
  38         if (readlink(rfname, tml, sizeof(tml)) > 0 &&
  39             !strcmp(tml, ".revoked.")) {
  40                 return true;
  41         };
  42
  43         return false;
  44 }
  45
  46 #ifdef UCERT_FULL
  47 /*
  48  * call usign -S ...
  49  * return WEXITSTATUS or -1 if fork fails
  50  */
  51 int usign_s(const char *msgfile, const char *seckeyfile, const char *sigfile, bool quiet) {
  52         pid_t pid;
  53         int status;
  54         const char *usign_argv[16] = {0};
  55         unsigned int usign_argc = 0;
  56
  57         usign_argv[usign_argc++] = USIGN_EXEC;
  58         usign_argv[usign_argc++] = "-S";
  59         usign_argv[usign_argc++] = "-m";
  60         usign_argv[usign_argc++] = msgfile;
  61         usign_argv[usign_argc++] = "-s";
  62         usign_argv[usign_argc++] = seckeyfile;
  63         usign_argv[usign_argc++] = "-x";
  64         usign_argv[usign_argc++] = sigfile;
  65
  66         if (quiet)
  67                 usign_argv[usign_argc++] = "-q";
  68
  69         pid = fork();
  70         switch (pid) {
  71         case -1:
  72                 return -1;
  73
  74         case 0:
  75                 execvp(usign_argv[0], (char *const *)usign_argv);
  76                 if (!quiet)
  77                         perror("Failed to execute usign");
  78                 _exit(1);
  79         }
  80
  81         waitpid(pid, &status, 0);
  82         return WEXITSTATUS(status);
  83 }
  84 #else
  85 int usign_s(const char *msgfile, const char *seckeyfile, const char *sigfile, bool quiet) {
  86         return -1;
  87 };
  88 #endif
  89
  90 /*
  91  * call usign -F ... and set fingerprint returned
  92  * return WEXITSTATUS or -1 if fork fails
  93  */
  94 static int usign_f(char fingerprint[17], const char *pubkeyfile, const char *seckeyfile, const char *sigfile, bool quiet) {
  95         int fds[2];
  96         pid_t pid;
  97         int status;
  98         const char *usign_argv[16] = {0};
  99         unsigned int usign_argc = 0;
 100
 101         if (pipe(fds))
 102                 return -1;
 103
 104         usign_argv[usign_argc++] = USIGN_EXEC;
 105         usign_argv[usign_argc++] = "-F";
 106
 107         if (pubkeyfile) {
 108                 usign_argv[usign_argc++] = "-p";
 109                 usign_argv[usign_argc++] = pubkeyfile;
 110         }
 111
 112         if (seckeyfile) {
 113                 usign_argv[usign_argc++] = "-s";
 114                 usign_argv[usign_argc++] = seckeyfile;
 115         }
 116
 117         if (sigfile) {
 118                 usign_argv[usign_argc++] = "-x";
 119                 usign_argv[usign_argc++] = sigfile;
 120         }
 121
 122         pid = fork();
 123         switch (pid) {
 124         case -1:
 125                 return -1;
 126
 127         case 0:
 128                 dup2(fds[1], 1);
 129
 130                 close(fds[0]);
 131                 close(fds[1]);
 132
 133                 execvp(usign_argv[0], (char *const *)usign_argv);
 134                 if (!quiet)
 135                         perror("Failed to execute usign");
 136                 _exit(1);
 137         }
 138
 139         waitpid(pid, &status, 0);
 140         status = WEXITSTATUS(status);
 141         if (fingerprint && !WEXITSTATUS(status)) {
 142                 ssize_t r;
 143                 memset(fingerprint, 0, 17);
 144                 r = read(fds[0], fingerprint, 17);
 145                 if (r < 16)
 146                         status = -1;
 147
 148                 fingerprint[16] = '\0';
 149
 150         }
 151         close(fds[0]);
 152         close(fds[1]);
 153         return status;
 154 }
 155
 156 /*
 157  * call usign -F -p ...
 158  */
 159 int usign_f_pubkey(char fingerprint[17], const char *pubkeyfile, bool quiet) {
 160         return usign_f(fingerprint, pubkeyfile, NULL, NULL, quiet);
 161 }
 162
 163 /*
 164  * call usign -F -s ...
 165  */
 166 int usign_f_seckey(char fingerprint[17], const char *seckeyfile, bool quiet) {
 167         return usign_f(fingerprint, NULL, seckeyfile, NULL, quiet);
 168 }
 169
 170 /*
 171  * call usign -F -x ...
 172  */
 173 int usign_f_sig(char fingerprint[17], const char *sigfile, bool quiet) {
 174         return usign_f(fingerprint, NULL, NULL, sigfile, quiet);
 175 }
 176
 177
 178 /*
 179  * call usign -V ...
 180  * return WEXITSTATUS or -1 if fork fails
 181  */
 182 int usign_v(const char *msgfile, const char *pubkeyfile,
 183             const char *pubkeydir, const char *sigfile, bool quiet) {
 184         pid_t pid;
 185         int status;
 186         const char *usign_argv[16] = {0};
 187         unsigned int usign_argc = 0;
 188         char fingerprint[17];
 189
 190         if (usign_f_sig(fingerprint, sigfile, quiet)) {
 191                 if (!quiet)
 192                         fprintf(stderr, "cannot get signing key fingerprint\n");
 193                 return 1;
 194         }
 195
 196         if (pubkeydir && _usign_key_is_revoked(fingerprint, pubkeydir)) {
 197                 if (!quiet)
 198                         fprintf(stderr, "key %s has been revoked!\n", fingerprint);
 199                 return 1;
 200         }
 201         usign_argv[usign_argc++] = USIGN_EXEC;
 202         usign_argv[usign_argc++] = "-V";
 203         usign_argv[usign_argc++] = "-m";
 204         usign_argv[usign_argc++] = msgfile;
 205
 206         if (quiet)
 207                 usign_argv[usign_argc++] = "-q";
 208
 209         if (pubkeyfile) {
 210                 usign_argv[usign_argc++] = "-p";
 211                 usign_argv[usign_argc++] = pubkeyfile;
 212         }
 213
 214         if (pubkeydir) {
 215                 usign_argv[usign_argc++] = "-P";
 216                 usign_argv[usign_argc++] = pubkeydir;
 217         }
 218
 219         if (sigfile) {
 220                 usign_argv[usign_argc++] = "-x";
 221                 usign_argv[usign_argc++] = sigfile;
 222         }
 223
 224         pid = fork();
 225         switch (pid) {
 226         case -1:
 227                 return -1;
 228
 229         case 0:
 230                 execvp(usign_argv[0], (char *const *)usign_argv);
 231                 if (!quiet)
 232                         perror("Failed to execute usign");
 233                 _exit(1);
 234         }
 235
 236         waitpid(pid, &status, 0);
 237         return WEXITSTATUS(status);
 238 }