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