lib/sigs.c

   1 /*
   2  * Copyright (c) 2022 Josh Rickmar <jrick@zettaport.com>
   3  *
   4  * Permission to use, copy, modify, and distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15  */
  16
  17 #include <sys/time.h>
  18 #include <sys/types.h>
  19 #include <sys/stat.h>
  20 #include <sys/socket.h>
  21 #include <sys/wait.h>
  22
  23 #include <stdlib.h>
  24 #include <stdio.h>
  25 #include <fcntl.h>
  26 #include <unistd.h>
  27 #include <string.h>
  28 #include <err.h>
  29 #include <assert.h>
  30
  31 #include "got_error.h"
  32 #include "got_date.h"
  33 #include "got_object.h"
  34 #include "got_opentemp.h"
  35
  36 #include "got_sigs.h"
  37 #include "got_compat.h"
  38 #include "buf.h"
  39
  40 #ifndef MIN
  41 #define MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
  42 #endif
  43
  44 #ifndef nitems
  45 #define nitems(_a)      (sizeof((_a)) / sizeof((_a)[0]))
  46 #endif
  47
  48 #ifndef GOT_TAG_PATH_SSH_KEYGEN
  49 #define GOT_TAG_PATH_SSH_KEYGEN "/usr/bin/ssh-keygen"
  50 #endif
  51
  52 #ifndef GOT_TAG_PATH_SIGNIFY
  53 #define GOT_TAG_PATH_SIGNIFY "/usr/bin/signify"
  54 #endif
  55
  56 const struct got_error *
  57 got_sigs_apply_unveil()
  58 {
  59         if (unveil(GOT_TAG_PATH_SSH_KEYGEN, "x") != 0) {
  60                 return got_error_from_errno2("unveil",
  61                     GOT_TAG_PATH_SSH_KEYGEN);
  62         }
  63         if (unveil(GOT_TAG_PATH_SIGNIFY, "x") != 0) {
  64                 return got_error_from_errno2("unveil",
  65                     GOT_TAG_PATH_SIGNIFY);
  66         }
  67
  68         return NULL;
  69 }
  70
  71 const struct got_error *
  72 got_sigs_sign_tag_ssh(pid_t *newpid, int *in_fd, int *out_fd,
  73     const char* key_file, int verbosity)
  74 {
  75         const struct got_error *error = NULL;
  76         int pid, in_pfd[2], out_pfd[2];
  77         const char* argv[11];
  78         int i = 0, j;
  79
  80         *newpid = -1;
  81         *in_fd = -1;
  82         *out_fd = -1;
  83
  84         argv[i++] = GOT_TAG_PATH_SSH_KEYGEN;
  85         argv[i++] = "-Y";
  86         argv[i++] = "sign";
  87         argv[i++] = "-f";
  88         argv[i++] = key_file;
  89         argv[i++] = "-n";
  90         argv[i++] = "git";
  91         if (verbosity <= 0) {
  92                 argv[i++] = "-q";
  93         } else {
  94                 /* ssh(1) allows up to 3 "-v" options. */
  95                 for (j = 0; j < MIN(3, verbosity); j++)
  96                         argv[i++] = "-v";
  97         }
  98         argv[i++] = NULL;
  99         assert(i <= nitems(argv));
 100
 101         if (pipe(in_pfd) == -1)
 102                 return got_error_from_errno("pipe");
 103         if (pipe(out_pfd) == -1)
 104                 return got_error_from_errno("pipe");
 105
 106         pid = fork();
 107         if (pid == -1) {
 108                 error = got_error_from_errno("fork");
 109                 close(in_pfd[0]);
 110                 close(in_pfd[1]);
 111                 close(out_pfd[0]);
 112                 close(out_pfd[1]);
 113                 return error;
 114         } else if (pid == 0) {
 115                 if (close(in_pfd[1]) == -1)
 116                         err(1, "close");
 117                 if (close(out_pfd[1]) == -1)
 118                         err(1, "close");
 119                 if (dup2(in_pfd[0], 0) == -1)
 120                         err(1, "dup2");
 121                 if (dup2(out_pfd[0], 1) == -1)
 122                         err(1, "dup2");
 123                 if (execv(GOT_TAG_PATH_SSH_KEYGEN, (char **const)argv) == -1)
 124                         err(1, "execv");
 125                 abort(); /* not reached */
 126         }
 127         if (close(in_pfd[0]) == -1)
 128                 return got_error_from_errno("close");
 129         if (close(out_pfd[0]) == -1)
 130                 return got_error_from_errno("close");
 131         *newpid = pid;
 132         *in_fd = in_pfd[1];
 133         *out_fd = out_pfd[1];
 134         return NULL;
 135 }
 136
 137 static char *
 138 signer_identity(const char *tagger)
 139 {
 140         char *lt, *gt;
 141
 142         lt = strstr(tagger, " <");
 143         gt = strrchr(tagger, '>');
 144         if (lt && gt && lt+1 < gt)
 145                 return strndup(lt+2, gt-lt-2);
 146         return NULL;
 147 }
 148
 149 static const char* BEGIN_SSH_SIG = "-----BEGIN SSH SIGNATURE-----\n";
 150 static const char* END_SSH_SIG = "-----END SSH SIGNATURE-----\n";
 151
 152 const char *
 153 got_sigs_get_tagmsg_ssh_signature(const char *tagmsg)
 154 {
 155         const char *s = tagmsg, *begin = NULL, *end = NULL;
 156
 157         while ((s = strstr(s, BEGIN_SSH_SIG)) != NULL) {
 158                 begin = s;
 159                 s += strlen(BEGIN_SSH_SIG);
 160         }
 161         if (begin)
 162                 end = strstr(begin+strlen(BEGIN_SSH_SIG), END_SSH_SIG);
 163         if (end == NULL)
 164                 return NULL;
 165         return (end[strlen(END_SSH_SIG)] == '\0') ? begin : NULL;
 166 }
 167
 168 static const struct got_error *
 169 got_tag_write_signed_data(BUF *buf, struct got_tag_object *tag,
 170     const char *start_sig)
 171 {
 172         const struct got_error *err = NULL;
 173         struct got_object_id *id;
 174         char *id_str = NULL;
 175         char *tagger = NULL;
 176         const char *tagmsg;
 177         char gmtoff[6];
 178         size_t len;
 179
 180         id = got_object_tag_get_object_id(tag);
 181         err = got_object_id_str(&id_str, id);
 182         if (err)
 183                 goto done;
 184
 185         const char *type_label = NULL;
 186         switch (got_object_tag_get_object_type(tag)) {
 187         case GOT_OBJ_TYPE_BLOB:
 188                 type_label = GOT_OBJ_LABEL_BLOB;
 189                 break;
 190         case GOT_OBJ_TYPE_TREE:
 191                 type_label = GOT_OBJ_LABEL_TREE;
 192                 break;
 193         case GOT_OBJ_TYPE_COMMIT:
 194                 type_label = GOT_OBJ_LABEL_COMMIT;
 195                 break;
 196         case GOT_OBJ_TYPE_TAG:
 197                 type_label = GOT_OBJ_LABEL_TAG;
 198                 break;
 199         default:
 200                 break;
 201         }
 202         got_date_format_gmtoff(gmtoff, sizeof(gmtoff),
 203             got_object_tag_get_tagger_gmtoff(tag));
 204         if (asprintf(&tagger, "%s %lld %s", got_object_tag_get_tagger(tag),
 205             (long long)got_object_tag_get_tagger_time(tag), gmtoff) == -1) {
 206                 err = got_error_from_errno("asprintf");
 207                 goto done;
 208         }
 209
 210         err = buf_puts(&len, buf, GOT_TAG_LABEL_OBJECT);
 211         if (err)
 212                 goto done;
 213         err = buf_puts(&len, buf, id_str);
 214         if (err)
 215                 goto done;
 216         err = buf_putc(buf, '\n');
 217         if (err)
 218                 goto done;
 219         err = buf_puts(&len, buf, GOT_TAG_LABEL_TYPE);
 220         if (err)
 221                 goto done;
 222         err = buf_puts(&len, buf, type_label);
 223         if (err)
 224                 goto done;
 225         err = buf_putc(buf, '\n');
 226         if (err)
 227                 goto done;
 228         err = buf_puts(&len, buf, GOT_TAG_LABEL_TAG);
 229         if (err)
 230                 goto done;
 231         err = buf_puts(&len, buf, got_object_tag_get_name(tag));
 232         if (err)
 233                 goto done;
 234         err = buf_putc(buf, '\n');
 235         if (err)
 236                 goto done;
 237         err = buf_puts(&len, buf, GOT_TAG_LABEL_TAGGER);
 238         if (err)
 239                 goto done;
 240         err = buf_puts(&len, buf, tagger);
 241         if (err)
 242                 goto done;
 243         err = buf_puts(&len, buf, "\n");
 244         if (err)
 245                 goto done;
 246         tagmsg = got_object_tag_get_message(tag);
 247         err = buf_append(&len, buf, tagmsg, start_sig-tagmsg);
 248         if (err)
 249                 goto done;
 250
 251 done:
 252         free(id_str);
 253         free(tagger);
 254         return err;
 255 }
 256
 257 const struct got_error *
 258 got_sigs_verify_tag_ssh(char **msg, struct got_tag_object *tag,
 259     const char *start_sig, const char* allowed_signers, const char* revoked,
 260     int verbosity)
 261 {
 262         const struct got_error *error = NULL;
 263         const char* argv[17];
 264         int pid, status, in_pfd[2], out_pfd[2];
 265         char* parsed_identity = NULL;
 266         const char *identity;
 267         char* tmppath = NULL;
 268         FILE *tmpsig, *out = NULL;
 269         BUF *buf;
 270         int i = 0, j;
 271
 272         *msg = NULL;
 273
 274         error = got_opentemp_named(&tmppath, &tmpsig,
 275             GOT_TMPDIR_STR "/got-tagsig");
 276         if (error)
 277                 goto done;
 278
 279         identity = got_object_tag_get_tagger(tag);
 280         parsed_identity = signer_identity(identity);
 281         if (parsed_identity != NULL)
 282                 identity = parsed_identity;
 283
 284         if (fputs(start_sig, tmpsig) == EOF) {
 285                 error = got_error_from_errno("fputs");
 286                 goto done;
 287         }
 288         if (fflush(tmpsig) == EOF) {
 289                 error = got_error_from_errno("fflush");
 290                 goto done;
 291         }
 292
 293         error = buf_alloc(&buf, 0);
 294         if (error)
 295                 goto done;
 296         error = got_tag_write_signed_data(buf, tag, start_sig);
 297         if (error)
 298                 goto done;
 299
 300         argv[i++] = GOT_TAG_PATH_SSH_KEYGEN;
 301         argv[i++] = "-Y";
 302         argv[i++] = "verify";
 303         argv[i++] = "-f";
 304         argv[i++] = allowed_signers;
 305         argv[i++] = "-I";
 306         argv[i++] = identity;
 307         argv[i++] = "-n";
 308         argv[i++] = "git";
 309         argv[i++] = "-s";
 310         argv[i++] = tmppath;
 311         if (revoked) {
 312                 argv[i++] = "-r";
 313                 argv[i++] = revoked;
 314         }
 315         if (verbosity > 0) {
 316                 /* ssh(1) allows up to 3 "-v" options. */
 317                 for (j = 0; j < MIN(3, verbosity); j++)
 318                         argv[i++] = "-v";
 319         }
 320         argv[i++] = NULL;
 321         assert(i <= nitems(argv));
 322
 323         if (pipe(in_pfd) == -1) {
 324                 error = got_error_from_errno("pipe");
 325                 goto done;
 326         }
 327         if (pipe(out_pfd) == -1) {
 328                 error = got_error_from_errno("pipe");
 329                 goto done;
 330         }
 331
 332         pid = fork();
 333         if (pid == -1) {
 334                 error = got_error_from_errno("fork");
 335                 close(in_pfd[0]);
 336                 close(in_pfd[1]);
 337                 close(out_pfd[0]);
 338                 close(out_pfd[1]);
 339                 return error;
 340         } else if (pid == 0) {
 341                 if (close(in_pfd[1]) == -1)
 342                         err(1, "close");
 343                 if (close(out_pfd[1]) == -1)
 344                         err(1, "close");
 345                 if (dup2(in_pfd[0], 0) == -1)
 346                         err(1, "dup2");
 347                 if (dup2(out_pfd[0], 1) == -1)
 348                         err(1, "dup2");
 349                 if (execv(GOT_TAG_PATH_SSH_KEYGEN, (char **const)argv) == -1)
 350                         err(1, "execv");
 351                 abort(); /* not reached */
 352         }
 353         if (close(in_pfd[0]) == -1) {
 354                 error = got_error_from_errno("close");
 355                 goto done;
 356         }
 357         if (close(out_pfd[0]) == -1) {
 358                 error = got_error_from_errno("close");
 359                 goto done;
 360         }
 361         if (buf_write_fd(buf, in_pfd[1]) == -1) {
 362                 error = got_error_from_errno("write");
 363                 goto done;
 364         }
 365         if (close(in_pfd[1]) == -1) {
 366                 error = got_error_from_errno("close");
 367                 goto done;
 368         }
 369         if (waitpid(pid, &status, 0) == -1) {
 370                 error = got_error_from_errno("waitpid");
 371                 goto done;
 372         }
 373         if (!WIFEXITED(status)) {
 374                 error = got_error(GOT_ERR_BAD_TAG_SIGNATURE);
 375                 goto done;
 376         }
 377
 378         out = fdopen(out_pfd[1], "r");
 379         if (out == NULL) {
 380                 error = got_error_from_errno("fdopen");
 381                 goto done;
 382         }
 383         error = buf_load(&buf, out);
 384         if (error)
 385                 goto done;
 386         error = buf_putc(buf, '\0');
 387         if (error)
 388                 goto done;
 389         if (close(out_pfd[1]) == -1) {
 390                 error = got_error_from_errno("close");
 391                 goto done;
 392         }
 393         out = NULL;
 394         *msg = buf_get(buf);
 395         if (WEXITSTATUS(status) != 0)
 396                 error = got_error(GOT_ERR_BAD_TAG_SIGNATURE);
 397
 398 done:
 399         free(parsed_identity);
 400         free(tmppath);
 401         if (tmpsig && fclose(tmpsig) == EOF && error == NULL)
 402                 error = got_error_from_errno("fclose");
 403         if (out && fclose(out) == EOF && error == NULL)
 404                 error = got_error_from_errno("fclose");
 405         return error;
 406 }