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 /*
  24  * check for revoker deadlink in pubkeydir
  25  * return true if a revoker exists, false otherwise
  26  */
  27 int _usign_key_is_revoked(const char *fingerprint, const char *pubkeydir) {
  28         char tml[64] = {0};
  29         char rfname[256] = {0};
  30
  31         snprintf(rfname, sizeof(rfname)-1, "%s/%s", pubkeydir, fingerprint);
  32         if (readlink(rfname, tml, sizeof(tml)) > 0 &&
  33             !strcmp(tml, ".revoked.")) {
  34                 return true;
  35         };
  36
  37         return false;
  38 }
  39
  40 /*
  41  * call usign -S ...
  42  * return WEXITSTATUS or -1 if fork or execv fails
  43  */
  44 int usign_s(const char *msgfile, const char *seckeyfile, const char *sigfile, bool quiet) {
  45         pid_t pid;
  46         int status;
  47         const char *usign_argv[16] = {0};
  48         unsigned int usign_argc = 0;
  49
  50         usign_argv[usign_argc++] = "/usr/bin/usign";
  51         usign_argv[usign_argc++] = "-S";
  52         usign_argv[usign_argc++] = "-m";
  53         usign_argv[usign_argc++] = msgfile;
  54         usign_argv[usign_argc++] = "-s";
  55         usign_argv[usign_argc++] = seckeyfile;
  56         usign_argv[usign_argc++] = "-x";
  57         usign_argv[usign_argc++] = sigfile;
  58
  59         if (quiet)
  60                 usign_argv[usign_argc++] = "-q";
  61
  62         pid = fork();
  63         switch (pid) {
  64         case -1:
  65                 return -1;
  66
  67         case 0:
  68                 if (execv(usign_argv[0], usign_argv))
  69                         return -1;
  70
  71                 break;
  72
  73         default:
  74                 waitpid(pid, &status, 0);
  75                 return WEXITSTATUS(status);
  76         }
  77
  78         return -1;
  79 }
  80
  81 /*
  82  * call usign -F ... and set fingerprint returned
  83  * return WEXITSTATUS or -1 if fork or execv fails
  84  */
  85 static int usign_f(char *fingerprint, const char *pubkeyfile, const char *seckeyfile, const char *sigfile) {
  86         int fds[2];
  87         pid_t pid;
  88         int status;
  89         const char *usign_argv[16] = {0};
  90         unsigned int usign_argc = 0;
  91
  92         if (pipe(fds))
  93                 return -1;
  94
  95         usign_argv[usign_argc++] = "/usr/bin/usign";
  96         usign_argv[usign_argc++] = "-F";
  97
  98         if (pubkeyfile) {
  99                 usign_argv[usign_argc++] = "-p";
 100                 usign_argv[usign_argc++] = pubkeyfile;
 101         }
 102
 103         if (seckeyfile) {
 104                 usign_argv[usign_argc++] = "-s";
 105                 usign_argv[usign_argc++] = seckeyfile;
 106         }
 107
 108         if (sigfile) {
 109                 usign_argv[usign_argc++] = "-x";
 110                 usign_argv[usign_argc++] = sigfile;
 111         }
 112
 113         pid = fork();
 114         switch (pid) {
 115         case -1:
 116                 return -1;
 117
 118         case 0:
 119                 dup2(fds[1], 1);
 120
 121                 close(0);
 122                 close(2);
 123                 close(fds[0]);
 124                 close(fds[1]);
 125
 126                 if (execv(usign_argv[0], usign_argv))
 127                         return -1;
 128
 129                 break;
 130
 131         default:
 132                 waitpid(pid, &status, 0);
 133                 if (fingerprint && !WEXITSTATUS(status)) {
 134                         memset(fingerprint, 0, 16);
 135                         read(fds[0], fingerprint, 16);
 136                         fingerprint[16] = '\0';
 137                 }
 138                 close(fds[0]);
 139                 close(fds[1]);
 140                 return WEXITSTATUS(status);
 141         }
 142
 143         return -1;
 144 }
 145
 146 /*
 147  * call usign -F -p ...
 148  */
 149 int usign_f_pubkey(char *fingerprint, const char *pubkeyfile) {
 150         return usign_f(fingerprint, pubkeyfile, NULL, NULL);
 151 }
 152
 153 /*
 154  * call usign -F -s ...
 155  */
 156 int usign_f_seckey(char *fingerprint, const char *seckeyfile) {
 157         return usign_f(fingerprint, NULL, seckeyfile, NULL);
 158 }
 159
 160 /*
 161  * call usign -F -x ...
 162  */
 163 int usign_f_sig(char *fingerprint, const char *sigfile) {
 164         return usign_f(fingerprint, NULL, NULL, sigfile);
 165 }
 166
 167
 168 /*
 169  * call usign -V ...
 170  * return WEXITSTATUS or -1 if fork or execv fails
 171  */
 172 int usign_v(const char *msgfile, const char *pubkeyfile,
 173             const char *pubkeydir, const char *sigfile, bool quiet) {
 174         pid_t pid;
 175         int status;
 176         const char *usign_argv[16] = {0};
 177         unsigned int usign_argc = 0;
 178         char fingerprint[17];
 179
 180         if (usign_f_sig(fingerprint, sigfile)) {
 181                 if (!quiet)
 182                         fprintf(stdout, "cannot get signing key fingerprint\n");
 183                 return 1;
 184         }
 185
 186         if (pubkeydir && _usign_key_is_revoked(fingerprint, pubkeydir)) {
 187                 if (!quiet)
 188                         fprintf(stdout, "key %s has been revoked!\n", fingerprint);
 189                 return 1;
 190         }
 191         usign_argv[usign_argc++] = "/usr/bin/usign";
 192         usign_argv[usign_argc++] = "-V";
 193         usign_argv[usign_argc++] = "-m";
 194         usign_argv[usign_argc++] = msgfile;
 195
 196         if (quiet)
 197                 usign_argv[usign_argc++] = "-q";
 198
 199         if (pubkeyfile) {
 200                 usign_argv[usign_argc++] = "-p";
 201                 usign_argv[usign_argc++] = pubkeyfile;
 202         }
 203
 204         if (pubkeydir) {
 205                 usign_argv[usign_argc++] = "-P";
 206                 usign_argv[usign_argc++] = pubkeydir;
 207         }
 208
 209         if (sigfile) {
 210                 usign_argv[usign_argc++] = "-x";
 211                 usign_argv[usign_argc++] = sigfile;
 212         }
 213
 214         pid = fork();
 215         switch (pid) {
 216         case -1:
 217                 return -1;
 218
 219         case 0:
 220                 if (execv(usign_argv[0], usign_argv))
 221                         return -1;
 222
 223                 break;
 224
 225         default:
 226                 waitpid(pid, &status, 0);
 227                 return WEXITSTATUS(status);
 228         }
 229
 230         return -1;
 231 }