misc/e4crypt.c

   1 /*
   2  * e4crypt.c - ext4 encryption management utility
   3  *
   4  * Copyright (c) 2014 Google, Inc.
   5  *      SHA512 implementation from libtomcrypt.
   6  *
   7  * Authors: Michael Halcrow <mhalcrow@google.com>,
   8  *      Ildar Muslukhov <ildarm@google.com>
   9  */
  10
  11 #ifndef _LARGEFILE_SOURCE
  12 #define _LARGEFILE_SOURCE
  13 #endif
  14
  15 #ifndef _LARGEFILE64_SOURCE
  16 #define _LARGEFILE64_SOURCE
  17 #endif
  18
  19 #ifndef _GNU_SOURCE
  20 #define _GNU_SOURCE
  21 #endif
  22
  23 #include "config.h"
  24 #include <assert.h>
  25 #include <errno.h>
  26 #include <getopt.h>
  27 #include <dirent.h>
  28 #include <errno.h>
  29 #include <stdarg.h>
  30 #include <stdio.h>
  31 #include <stdlib.h>
  32 #include <string.h>
  33 #include <mntent.h>
  34 #include <sys/ioctl.h>
  35 #include <sys/stat.h>
  36 #include <sys/types.h>
  37 #include <fcntl.h>
  38 #include <termios.h>
  39 #include <unistd.h>
  40 #include <signal.h>
  41 #if !defined(HAVE_ADD_KEY) || !defined(HAVE_KEYCTL)
  42 #include <sys/syscall.h>
  43 #endif
  44 #ifdef HAVE_SYS_KEY_H
  45 #include <sys/key.h>
  46 #endif
  47
  48 #include "ext2fs/ext2_fs.h"
  49 #include "ext2fs/ext2fs.h"
  50 #include "uuid/uuid.h"
  51
  52 /* special process keyring shortcut IDs */
  53 #define KEY_SPEC_THREAD_KEYRING         -1
  54 #define KEY_SPEC_PROCESS_KEYRING        -2
  55 #define KEY_SPEC_SESSION_KEYRING        -3
  56 #define KEY_SPEC_USER_KEYRING           -4
  57 #define KEY_SPEC_USER_SESSION_KEYRING   -5
  58 #define KEY_SPEC_GROUP_KEYRING          -6
  59
  60 #define KEYCTL_GET_KEYRING_ID           0
  61 #define KEYCTL_JOIN_SESSION_KEYRING     1
  62 #define KEYCTL_DESCRIBE                 6
  63 #define KEYCTL_SEARCH                   10
  64 #define KEYCTL_SESSION_TO_PARENT        18
  65
  66 typedef __s32 key_serial_t;
  67
  68 #define EXT4_KEY_REF_STR_BUF_SIZE ((EXT4_KEY_DESCRIPTOR_SIZE * 2) + 1)
  69
  70 #ifndef EXT4_IOC_GET_ENCRYPTION_PWSALT
  71 #define EXT4_IOC_GET_ENCRYPTION_PWSALT  _IOW('f', 20, __u8[16])
  72 #endif
  73
  74 #define OPT_VERBOSE     0x0001
  75 #define OPT_QUIET       0x0002
  76
  77 int options;
  78
  79 #ifndef HAVE_KEYCTL
  80 static long keyctl(int cmd, ...)
  81 {
  82         va_list va;
  83         unsigned long arg2, arg3, arg4, arg5;
  84
  85         va_start(va, cmd);
  86         arg2 = va_arg(va, unsigned long);
  87         arg3 = va_arg(va, unsigned long);
  88         arg4 = va_arg(va, unsigned long);
  89         arg5 = va_arg(va, unsigned long);
  90         va_end(va);
  91         return syscall(__NR_keyctl, cmd, arg2, arg3, arg4, arg5);
  92 }
  93 #endif
  94
  95 #ifndef HAVE_ADD_KEY
  96 static key_serial_t add_key(const char *type, const char *description,
  97                             const void *payload, size_t plen,
  98                             key_serial_t keyring)
  99 {
 100         return syscall(__NR_add_key, type, description, payload,
 101                        plen, keyring);
 102 }
 103 #endif
 104
 105 static const unsigned char *hexchars = (const unsigned char *) "0123456789abcdef";
 106 static const size_t hexchars_size = 16;
 107
 108 #define SHA512_LENGTH 64
 109 #define EXT2FS_KEY_TYPE_LOGON "logon"
 110 #define EXT2FS_KEY_DESC_PREFIX "ext4:"
 111 #define EXT2FS_KEY_DESC_PREFIX_SIZE 5
 112
 113 #define EXT4_IOC_SET_ENCRYPTION_POLICY      _IOR('f', 19, struct ext4_encryption_policy)
 114 #define EXT4_IOC_GET_ENCRYPTION_POLICY      _IOW('f', 21, struct ext4_encryption_policy)
 115
 116 static int int_log2(int arg)
 117 {
 118         int     l = 0;
 119
 120         arg >>= 1;
 121         while (arg) {
 122                 l++;
 123                 arg >>= 1;
 124         }
 125         return l;
 126 }
 127
 128 static void validate_paths(int argc, char *argv[], int path_start_index)
 129 {
 130         int x;
 131         int valid = 1;
 132         struct stat st;
 133
 134         for (x = path_start_index; x < argc; x++) {
 135                 int ret = access(argv[x], W_OK);
 136                 if (ret) {
 137                 invalid:
 138                         perror(argv[x]);
 139                         valid = 0;
 140                         continue;
 141                 }
 142                 ret = stat(argv[x], &st);
 143                 if (ret < 0)
 144                         goto invalid;
 145                 if (!S_ISDIR(st.st_mode)) {
 146                         fprintf(stderr, "%s is not a directory\n", argv[x]);
 147                         goto invalid;
 148                 }
 149         }
 150         if (!valid)
 151                 exit(1);
 152 }
 153
 154 static int hex2byte(const char *hex, size_t hex_size, unsigned char *bytes,
 155                     size_t bytes_size)
 156 {
 157         size_t x;
 158         unsigned char *h, *l;
 159
 160         if (hex_size % 2)
 161                 return -EINVAL;
 162         for (x = 0; x < hex_size; x += 2) {
 163                 h = memchr(hexchars, hex[x], hexchars_size);
 164                 if (!h)
 165                         return -EINVAL;
 166                 l = memchr(hexchars, hex[x + 1], hexchars_size);
 167                 if (!l)
 168                         return -EINVAL;
 169                 if ((x >> 1) >= bytes_size)
 170                         return -EINVAL;
 171                 bytes[x >> 1] = (((unsigned char)(h - hexchars) << 4) +
 172                                  (unsigned char)(l - hexchars));
 173         }
 174         return 0;
 175 }
 176
 177 /*
 178  * Salt handling
 179  */
 180 struct salt {
 181         unsigned char *salt;
 182         char key_ref_str[EXT4_KEY_REF_STR_BUF_SIZE];
 183         unsigned char key_desc[EXT4_KEY_DESCRIPTOR_SIZE];
 184         unsigned char key[EXT4_MAX_KEY_SIZE];
 185         size_t salt_len;
 186 };
 187 struct salt *salt_list;
 188 unsigned num_salt;
 189 unsigned max_salt;
 190 char in_passphrase[EXT4_MAX_PASSPHRASE_SIZE];
 191
 192 static struct salt *find_by_salt(unsigned char *salt, size_t salt_len)
 193 {
 194         unsigned int i;
 195         struct salt *p;
 196
 197         for (i = 0, p = salt_list; i < num_salt; i++, p++)
 198                 if ((p->salt_len == salt_len) &&
 199                     !memcmp(p->salt, salt, salt_len))
 200                         return p;
 201         return NULL;
 202 }
 203
 204 static void add_salt(unsigned char *salt, size_t salt_len)
 205 {
 206         if (find_by_salt(salt, salt_len))
 207                 return;
 208         if (num_salt >= max_salt) {
 209                 max_salt = num_salt + 10;
 210                 salt_list = realloc(salt_list, max_salt * sizeof(struct salt));
 211                 if (!salt_list) {
 212                         fprintf(stderr, "Couldn't allocate salt list\n");
 213                         exit(1);
 214                 }
 215         }
 216         salt_list[num_salt].salt = salt;
 217         salt_list[num_salt].salt_len = salt_len;
 218         num_salt++;
 219 }
 220
 221 static void clear_secrets(void)
 222 {
 223         if (salt_list) {
 224                 memset(salt_list, 0, sizeof(struct salt) * max_salt);
 225                 free(salt_list);
 226                 salt_list = NULL;
 227         }
 228         memset(in_passphrase, 0, sizeof(in_passphrase));
 229 }
 230
 231 static void die_signal_handler(int signum EXT2FS_ATTR((unused)),
 232                                siginfo_t *siginfo EXT2FS_ATTR((unused)),
 233                                void *context EXT2FS_ATTR((unused)))
 234 {
 235         clear_secrets();
 236         exit(-1);
 237 }
 238
 239 static void sigcatcher_setup(void)
 240 {
 241         struct sigaction        sa;
 242
 243         memset(&sa, 0, sizeof(struct sigaction));
 244         sa.sa_sigaction = die_signal_handler;
 245         sa.sa_flags = SA_SIGINFO;
 246
 247         sigaction(SIGHUP, &sa, 0);
 248         sigaction(SIGINT, &sa, 0);
 249         sigaction(SIGQUIT, &sa, 0);
 250         sigaction(SIGFPE, &sa, 0);
 251         sigaction(SIGILL, &sa, 0);
 252         sigaction(SIGBUS, &sa, 0);
 253         sigaction(SIGSEGV, &sa, 0);
 254         sigaction(SIGABRT, &sa, 0);
 255         sigaction(SIGPIPE, &sa, 0);
 256         sigaction(SIGALRM, &sa, 0);
 257         sigaction(SIGTERM, &sa, 0);
 258         sigaction(SIGUSR1, &sa, 0);
 259         sigaction(SIGUSR2, &sa, 0);
 260         sigaction(SIGPOLL, &sa, 0);
 261         sigaction(SIGPROF, &sa, 0);
 262         sigaction(SIGSYS, &sa, 0);
 263         sigaction(SIGTRAP, &sa, 0);
 264         sigaction(SIGVTALRM, &sa, 0);
 265         sigaction(SIGXCPU, &sa, 0);
 266         sigaction(SIGXFSZ, &sa, 0);
 267 }
 268
 269
 270 #define PARSE_FLAGS_NOTSUPP_OK  0x0001
 271 #define PARSE_FLAGS_FORCE_FN    0x0002
 272
 273 static void parse_salt(char *salt_str, int flags)
 274 {
 275         unsigned char buf[EXT4_MAX_SALT_SIZE];
 276         char *cp = salt_str;
 277         unsigned char *salt_buf;
 278         int fd, ret, salt_len = 0;
 279
 280         if (flags & PARSE_FLAGS_FORCE_FN)
 281                 goto salt_from_filename;
 282         if (strncmp(cp, "s:", 2) == 0) {
 283                 cp += 2;
 284                 salt_len = strlen(cp);
 285                 if (salt_len >= EXT4_MAX_SALT_SIZE)
 286                         goto invalid_salt;
 287                 strncpy((char *) buf, cp, sizeof(buf));
 288         } else if (cp[0] == '/') {
 289         salt_from_filename:
 290                 fd = open(cp, O_RDONLY | O_DIRECTORY);
 291                 if (fd == -1 && errno == ENOTDIR)
 292                         fd = open(cp, O_RDONLY);
 293                 if (fd == -1) {
 294                         perror(cp);
 295                         exit(1);
 296                 }
 297                 ret = ioctl(fd, EXT4_IOC_GET_ENCRYPTION_PWSALT, &buf);
 298                 close(fd);
 299                 if (ret < 0) {
 300                         if (flags & PARSE_FLAGS_NOTSUPP_OK)
 301                                 return;
 302                         perror("EXT4_IOC_GET_ENCRYPTION_PWSALT");
 303                         exit(1);
 304                 }
 305                 if (options & OPT_VERBOSE) {
 306                         char tmp[80];
 307                         uuid_unparse(buf, tmp);
 308                         printf("%s has pw salt %s\n", cp, tmp);
 309                 }
 310                 salt_len = 16;
 311         } else if (strncmp(cp, "f:", 2) == 0) {
 312                 cp += 2;
 313                 goto salt_from_filename;
 314         } else if (strncmp(cp, "0x", 2) == 0) {
 315                 unsigned char *h, *l;
 316
 317                 cp += 2;
 318                 if (strlen(cp) & 1)
 319                         goto invalid_salt;
 320                 while (*cp) {
 321                         if (salt_len >= EXT4_MAX_SALT_SIZE)
 322                                 goto invalid_salt;
 323                         h = memchr(hexchars, *cp++, hexchars_size);
 324                         l = memchr(hexchars, *cp++, hexchars_size);
 325                         if (!h || !l)
 326                                 goto invalid_salt;
 327                         buf[salt_len++] =
 328                                 (((unsigned char)(h - hexchars) << 4) +
 329                                  (unsigned char)(l - hexchars));
 330                 }
 331         } else if (uuid_parse(cp, buf) == 0) {
 332                 salt_len = 16;
 333         } else {
 334         invalid_salt:
 335                 fprintf(stderr, "Invalid salt: %s\n", salt_str);
 336                 exit(1);
 337         }
 338         salt_buf = malloc(salt_len);
 339         if (!salt_buf) {
 340                 fprintf(stderr, "Couldn't allocate salt\n");
 341                 exit(1);
 342         }
 343         memcpy(salt_buf, buf, salt_len);
 344         add_salt(salt_buf, salt_len);
 345 }
 346
 347 static void set_policy(struct salt *set_salt, int pad,
 348                        int argc, char *argv[], int path_start_index)
 349 {
 350         struct salt *salt;
 351         struct ext4_encryption_policy policy;
 352         uuid_t  uu;
 353         int fd;
 354         int x;
 355         int rc;
 356
 357         if ((pad != 4) && (pad != 8) &&
 358                  (pad != 16) && (pad != 32)) {
 359                 fprintf(stderr, "Invalid padding %d\n", pad);
 360                 exit(1);
 361         }
 362
 363         for (x = path_start_index; x < argc; x++) {
 364                 fd = open(argv[x], O_DIRECTORY);
 365                 if (fd == -1) {
 366                         perror(argv[x]);
 367                         exit(1);
 368                 }
 369                 if (set_salt)
 370                         salt = set_salt;
 371                 else {
 372                         if (ioctl(fd, EXT4_IOC_GET_ENCRYPTION_PWSALT,
 373                                   &uu) < 0) {
 374                                 perror("EXT4_IOC_GET_ENCRYPTION_PWSALT");
 375                                 exit(1);
 376                         }
 377                         salt = find_by_salt(uu, sizeof(uu));
 378                         if (!salt) {
 379                                 fprintf(stderr, "Couldn't find salt!?!\n");
 380                                 exit(1);
 381                         }
 382                 }
 383                 policy.version = 0;
 384                 policy.contents_encryption_mode =
 385                         EXT4_ENCRYPTION_MODE_AES_256_XTS;
 386                 policy.filenames_encryption_mode =
 387                         EXT4_ENCRYPTION_MODE_AES_256_CTS;
 388                 policy.flags = int_log2(pad >> 2);
 389                 memcpy(policy.master_key_descriptor, salt->key_desc,
 390                        EXT4_KEY_DESCRIPTOR_SIZE);
 391                 rc = ioctl(fd, EXT4_IOC_SET_ENCRYPTION_POLICY, &policy);
 392                 close(fd);
 393                 if (rc) {
 394                         printf("Error [%s] setting policy.\nThe key descriptor "
 395                                "[%s] may not match the existing encryption "
 396                                "context for directory [%s].\n",
 397                                strerror(errno), salt->key_ref_str, argv[x]);
 398                         continue;
 399                 }
 400                 printf("Key with descriptor [%s] applied to %s.\n",
 401                        salt->key_ref_str, argv[x]);
 402         }
 403 }
 404
 405 static void pbkdf2_sha512(const char *passphrase, struct salt *salt,
 406                           unsigned int count,
 407                           unsigned char derived_key[EXT4_MAX_KEY_SIZE])
 408 {
 409         size_t passphrase_size = strlen(passphrase);
 410         unsigned char buf[SHA512_LENGTH + EXT4_MAX_PASSPHRASE_SIZE] = {0};
 411         unsigned char tempbuf[SHA512_LENGTH] = {0};
 412         char final[SHA512_LENGTH] = {0};
 413         unsigned char saltbuf[EXT4_MAX_SALT_SIZE + EXT4_MAX_PASSPHRASE_SIZE] = {0};
 414         int actual_buf_len = SHA512_LENGTH + passphrase_size;
 415         int actual_saltbuf_len = EXT4_MAX_SALT_SIZE + passphrase_size;
 416         unsigned int x, y;
 417         __u32 *final_u32 = (__u32 *)final;
 418         __u32 *temp_u32 = (__u32 *)tempbuf;
 419
 420         if (passphrase_size > EXT4_MAX_PASSPHRASE_SIZE) {
 421                 printf("Passphrase size is %zd; max is %d.\n", passphrase_size,
 422                        EXT4_MAX_PASSPHRASE_SIZE);
 423                 exit(1);
 424         }
 425         if (salt->salt_len > EXT4_MAX_SALT_SIZE) {
 426                 printf("Salt size is %zd; max is %d.\n", salt->salt_len,
 427                        EXT4_MAX_SALT_SIZE);
 428                 exit(1);
 429         }
 430         assert(EXT4_MAX_KEY_SIZE <= SHA512_LENGTH);
 431
 432         memcpy(saltbuf, salt->salt, salt->salt_len);
 433         memcpy(&saltbuf[EXT4_MAX_SALT_SIZE], passphrase, passphrase_size);
 434
 435         memcpy(&buf[SHA512_LENGTH], passphrase, passphrase_size);
 436
 437         for (x = 0; x < count; ++x) {
 438                 if (x == 0) {
 439                         ext2fs_sha512(saltbuf, actual_saltbuf_len, tempbuf);
 440                 } else {
 441                         /*
 442                          * buf: [previous hash || passphrase]
 443                          */
 444                         memcpy(buf, tempbuf, SHA512_LENGTH);
 445                         ext2fs_sha512(buf, actual_buf_len, tempbuf);
 446                 }
 447                 for (y = 0; y < (sizeof(final) / sizeof(*final_u32)); ++y)
 448                         final_u32[y] = final_u32[y] ^ temp_u32[y];
 449         }
 450         memcpy(derived_key, final, EXT4_MAX_KEY_SIZE);
 451 }
 452
 453 static int disable_echo(struct termios *saved_settings)
 454 {
 455         struct termios current_settings;
 456         int rc = 0;
 457
 458         rc = tcgetattr(0, &current_settings);
 459         if (rc)
 460                 return rc;
 461         *saved_settings = current_settings;
 462         current_settings.c_lflag &= ~ECHO;
 463         rc = tcsetattr(0, TCSANOW, &current_settings);
 464
 465         return rc;
 466 }
 467
 468 static void get_passphrase(char *passphrase, int len)
 469 {
 470         char *p;
 471         struct termios current_settings;
 472
 473         assert(len > 0);
 474         disable_echo(&current_settings);
 475         p = fgets(passphrase, len, stdin);
 476         tcsetattr(0, TCSANOW, &current_settings);
 477         printf("\n");
 478         if (!p) {
 479                 printf("Aborting.\n");
 480                 exit(1);
 481         }
 482         p = strrchr(passphrase, '\n');
 483         if (!p)
 484                 p = passphrase + len - 1;
 485         *p = '\0';
 486 }
 487
 488 struct keyring_map {
 489         char name[4];
 490         size_t name_len;
 491         int code;
 492 };
 493
 494 static const struct keyring_map keyrings[] = {
 495         {"@us", 3, KEY_SPEC_USER_SESSION_KEYRING},
 496         {"@u", 2, KEY_SPEC_USER_KEYRING},
 497         {"@s", 2, KEY_SPEC_SESSION_KEYRING},
 498         {"@g", 2, KEY_SPEC_GROUP_KEYRING},
 499         {"@p", 2, KEY_SPEC_PROCESS_KEYRING},
 500         {"@t", 2, KEY_SPEC_THREAD_KEYRING},
 501 };
 502
 503 static int get_keyring_id(const char *keyring)
 504 {
 505         unsigned int x;
 506         char *end;
 507
 508         /*
 509          * If no keyring is specified, by default use either the user
 510          * session keyring or the session keyring.  Fetching the
 511          * session keyring will return the user session keyring if no
 512          * session keyring has been set.
 513          */
 514         if (keyring == NULL)
 515                 return KEY_SPEC_SESSION_KEYRING;
 516         for (x = 0; x < (sizeof(keyrings) / sizeof(keyrings[0])); ++x) {
 517                 if (strcmp(keyring, keyrings[x].name) == 0) {
 518                         return keyrings[x].code;
 519                 }
 520         }
 521         x = strtoul(keyring, &end, 10);
 522         if (*end == '\0') {
 523                 if (keyctl(KEYCTL_DESCRIBE, x, NULL, 0) < 0)
 524                         return 0;
 525                 return x;
 526         }
 527         return 0;
 528 }
 529
 530 static void generate_key_ref_str(struct salt *salt)
 531 {
 532         unsigned char key_ref1[SHA512_LENGTH];
 533         unsigned char key_ref2[SHA512_LENGTH];
 534         int x;
 535
 536         ext2fs_sha512(salt->key, EXT4_MAX_KEY_SIZE, key_ref1);
 537         ext2fs_sha512(key_ref1, SHA512_LENGTH, key_ref2);
 538         memcpy(salt->key_desc, key_ref2, EXT4_KEY_DESCRIPTOR_SIZE);
 539         for (x = 0; x < EXT4_KEY_DESCRIPTOR_SIZE; ++x) {
 540                 sprintf(&salt->key_ref_str[x * 2], "%02x",
 541                         salt->key_desc[x]);
 542         }
 543         salt->key_ref_str[EXT4_KEY_REF_STR_BUF_SIZE - 1] = '\0';
 544 }
 545
 546 static void insert_key_into_keyring(const char *keyring, struct salt *salt)
 547 {
 548         int keyring_id = get_keyring_id(keyring);
 549         struct ext4_encryption_key key;
 550         char key_ref_full[EXT2FS_KEY_DESC_PREFIX_SIZE +
 551                           EXT4_KEY_REF_STR_BUF_SIZE];
 552         int rc;
 553
 554         if (keyring_id == 0) {
 555                 printf("Invalid keyring [%s].\n", keyring);
 556                 exit(1);
 557         }
 558         sprintf(key_ref_full, "%s%s", EXT2FS_KEY_DESC_PREFIX,
 559                 salt->key_ref_str);
 560         rc = keyctl(KEYCTL_SEARCH, keyring_id, EXT2FS_KEY_TYPE_LOGON,
 561                     key_ref_full, 0);
 562         if (rc != -1) {
 563                 if ((options & OPT_QUIET) == 0)
 564                         printf("Key with descriptor [%s] already exists\n",
 565                                salt->key_ref_str);
 566                 return;
 567         } else if ((rc == -1) && (errno != ENOKEY)) {
 568                 printf("keyctl_search failed: %s\n", strerror(errno));
 569                 if (errno == -EINVAL)
 570                         printf("Keyring [%s] is not available.\n", keyring);
 571                 exit(1);
 572         }
 573         key.mode = EXT4_ENCRYPTION_MODE_AES_256_XTS;
 574         memcpy(key.raw, salt->key, EXT4_MAX_KEY_SIZE);
 575         key.size = EXT4_MAX_KEY_SIZE;
 576
 577         /*
 578          * We need to do this instead of simply adding the key to
 579          * KEY_SPEC_SESSION_KEYRING since trying to add a key to a
 580          * session keyring that does not yet exist will cause the
 581          * kernel to create a session keyring --- which will then get
 582          * garbage collected as soon as e4crypt exits.
 583          *
 584          * The fact that the keyctl system call and the add_key system
 585          * call treats KEY_SPEC_SESSION_KEYRING differently when a
 586          * session keyring does not exist is very unfortunate and
 587          * confusing, but so it goes...
 588          */
 589         if (keyring_id == KEY_SPEC_SESSION_KEYRING) {
 590                 keyring_id = keyctl(KEYCTL_GET_KEYRING_ID, keyring_id, 0);
 591                 if (keyring_id < 0) {
 592                         printf("Error getting session keyring ID: %s\n",
 593                                strerror(errno));
 594                         exit(1);
 595                 }
 596         }
 597         rc = add_key(EXT2FS_KEY_TYPE_LOGON, key_ref_full, (void *)&key,
 598                      sizeof(key), keyring_id);
 599         if (rc == -1) {
 600                 if (errno == EDQUOT) {
 601                         printf("Error adding key to keyring; quota exceeded\n");
 602                 } else {
 603                         printf("Error adding key with key descriptor [%s]: "
 604                                "%s\n", salt->key_ref_str, strerror(errno));
 605                 }
 606                 exit(1);
 607         } else {
 608                 if ((options & OPT_QUIET) == 0)
 609                         printf("Added key with descriptor [%s]\n",
 610                                salt->key_ref_str);
 611         }
 612 }
 613
 614 static void get_default_salts(void)
 615 {
 616         FILE    *f = setmntent("/etc/mtab", "r");
 617         struct mntent *mnt;
 618
 619         while (f && ((mnt = getmntent(f)) != NULL)) {
 620                 if (strcmp(mnt->mnt_type, "ext4") ||
 621                     access(mnt->mnt_dir, R_OK))
 622                         continue;
 623                 parse_salt(mnt->mnt_dir, PARSE_FLAGS_NOTSUPP_OK);
 624         }
 625         endmntent(f);
 626 }
 627
 628 /* Functions which implement user commands */
 629
 630 struct cmd_desc {
 631         const char *cmd_name;
 632         void (*cmd_func)(int, char **, const struct cmd_desc *);
 633         const char *cmd_desc;
 634         const char *cmd_help;
 635         int cmd_flags;
 636 };
 637
 638 #define CMD_HIDDEN      0x0001
 639
 640 static void do_help(int argc, char **argv, const struct cmd_desc *cmd);
 641
 642 #define add_key_desc "adds a key to the user's keyring"
 643 #define add_key_help \
 644 "e4crypt add_key -S salt [ -k keyring ] [-v] [-q] [ path ... ]\n\n" \
 645 "Prompts the user for a passphrase and inserts it into the specified\n" \
 646 "keyring.  If no keyring is specified, e4crypt will use the session\n" \
 647 "keyring if it exists or the user session keyring if it does not.\n\n" \
 648 "If one or more directory paths are specified, e4crypt will try to\n" \
 649 "set the policy of those directories to use the key just entered by\n" \
 650 "the user.\n"
 651
 652 static void do_add_key(int argc, char **argv, const struct cmd_desc *cmd)
 653 {
 654         struct salt *salt;
 655         char *keyring = NULL;
 656         int i, opt, pad = 4;
 657         unsigned j;
 658
 659         while ((opt = getopt(argc, argv, "k:S:p:vq")) != -1) {
 660                 switch (opt) {
 661                 case 'k':
 662                         /* Specify a keyring. */
 663                         keyring = optarg;
 664                         break;
 665                 case 'p':
 666                         pad = atoi(optarg);
 667                         break;
 668                 case 'S':
 669                         /* Salt value for passphrase. */
 670                         parse_salt(optarg, 0);
 671                         break;
 672                 case 'v':
 673                         options |= OPT_VERBOSE;
 674                         break;
 675                 case 'q':
 676                         options |= OPT_QUIET;
 677                         break;
 678                 default:
 679                         fprintf(stderr, "Unrecognized option: %c\n", opt);
 680                 case '?':
 681                         fputs("USAGE:\n  ", stderr);
 682                         fputs(cmd->cmd_help, stderr);
 683                         exit(1);
 684                 }
 685         }
 686         if (num_salt == 0)
 687                 get_default_salts();
 688         if (num_salt == 0) {
 689                 fprintf(stderr, "No salt values available\n");
 690                 exit(1);
 691         }
 692         validate_paths(argc, argv, optind);
 693         for (i = optind; i < argc; i++)
 694                 parse_salt(argv[i], PARSE_FLAGS_FORCE_FN);
 695         printf("Enter passphrase (echo disabled): ");
 696         get_passphrase(in_passphrase, sizeof(in_passphrase));
 697         for (j = 0, salt = salt_list; j < num_salt; j++, salt++) {
 698                 pbkdf2_sha512(in_passphrase, salt,
 699                               EXT4_PBKDF2_ITERATIONS, salt->key);
 700                 generate_key_ref_str(salt);
 701                 insert_key_into_keyring(keyring, salt);
 702         }
 703         if (optind != argc)
 704                 set_policy(NULL, pad, argc, argv, optind);
 705         clear_secrets();
 706         exit(0);
 707 }
 708
 709 #define set_policy_desc "sets a policy for directories"
 710 #define set_policy_help \
 711 "e4crypt set_policy policy path ... \n\n" \
 712 "Sets the policy for the directories specified on the command line.\n" \
 713 "All directories must be empty to set the policy; if the directory\n" \
 714 "already has a policy established, e4crypt will validate that it the\n" \
 715 "policy matches what was specified.  A policy is an encryption key\n" \
 716 "identifier consisting of 16 hexadecimal characters.\n"
 717
 718 static void do_set_policy(int argc, char **argv, const struct cmd_desc *cmd)
 719 {
 720         struct salt saltbuf;
 721         int c, pad = 4;
 722
 723         while ((c = getopt (argc, argv, "p:")) != EOF) {
 724                 switch (c) {
 725                 case 'p':
 726                         pad = atoi(optarg);
 727                         break;
 728                 }
 729         }
 730
 731         if (argc < optind + 2) {
 732                 fprintf(stderr, "Missing required argument(s).\n\n");
 733                 fputs("USAGE:\n  ", stderr);
 734                 fputs(cmd->cmd_help, stderr);
 735                 exit(1);
 736         }
 737
 738         if ((strlen(argv[optind]) != (EXT4_KEY_DESCRIPTOR_SIZE * 2)) ||
 739             hex2byte(argv[optind], (EXT4_KEY_DESCRIPTOR_SIZE * 2),
 740                      saltbuf.key_desc, EXT4_KEY_DESCRIPTOR_SIZE)) {
 741                 printf("Invalid key descriptor [%s]. Valid characters "
 742                        "are 0-9 and a-f, lower case.  "
 743                        "Length must be %d.\n",
 744                        argv[optind], (EXT4_KEY_DESCRIPTOR_SIZE * 2));
 745                         exit(1);
 746         }
 747         validate_paths(argc, argv, optind+1);
 748         strcpy(saltbuf.key_ref_str, argv[optind]);
 749         set_policy(&saltbuf, pad, argc, argv, optind+1);
 750         exit(0);
 751 }
 752
 753 #define get_policy_desc "get the encryption for directories"
 754 #define get_policy_help \
 755 "e4crypt get_policy path ... \n\n" \
 756 "Gets the policy for the directories specified on the command line.\n"
 757
 758 static void do_get_policy(int argc, char **argv, const struct cmd_desc *cmd)
 759 {
 760         struct ext4_encryption_policy policy;
 761         struct stat st;
 762         int i, j, fd, rc;
 763
 764         if (argc < 2) {
 765                 fprintf(stderr, "Missing required argument(s).\n\n");
 766                 fputs("USAGE:\n  ", stderr);
 767                 fputs(cmd->cmd_help, stderr);
 768                 exit(1);
 769         }
 770
 771         for (i = 1; i < argc; i++) {
 772                 if (stat(argv[i], &st) < 0) {
 773                         perror(argv[i]);
 774                         continue;
 775                 }
 776                 fd = open(argv[i],
 777                           S_ISDIR(st.st_mode) ? O_DIRECTORY : O_RDONLY);
 778                 if (fd == -1) {
 779                         perror(argv[i]);
 780                         exit(1);
 781                 }
 782                 rc = ioctl(fd, EXT4_IOC_GET_ENCRYPTION_POLICY, &policy);
 783                 close(fd);
 784                 if (rc) {
 785                         printf("Error getting policy for %s: %s\n",
 786                                argv[i], strerror(errno));
 787                         continue;
 788                 }
 789                 printf("%s: ", argv[i]);
 790                 for (j = 0; j < EXT4_KEY_DESCRIPTOR_SIZE; j++) {
 791                         printf("%02x", (unsigned char) policy.master_key_descriptor[j]);
 792                 }
 793                 fputc('\n', stdout);
 794         }
 795         exit(0);
 796 }
 797
 798 #define new_session_desc "give the invoking process a new session keyring"
 799 #define new_session_help \
 800 "e4crypt new_session\n\n" \
 801 "Give the invoking process (typically a shell) a new session keyring,\n" \
 802 "discarding its old session keyring.\n"
 803
 804 static void do_new_session(int argc, char **argv EXT2FS_ATTR((unused)),
 805                            const struct cmd_desc *cmd)
 806 {
 807         long keyid, ret;
 808
 809         if (argc > 1) {
 810                 fputs("Excess arguments\n\n", stderr);
 811                 fputs(cmd->cmd_help, stderr);
 812                 exit(1);
 813         }
 814         keyid = keyctl(KEYCTL_JOIN_SESSION_KEYRING, NULL);
 815         if (keyid < 0) {
 816                 perror("KEYCTL_JOIN_SESSION_KEYRING");
 817                 exit(1);
 818         }
 819         ret = keyctl(KEYCTL_SESSION_TO_PARENT, NULL);
 820         if (ret < 0) {
 821                 perror("KEYCTL_SESSION_TO_PARENT");
 822                 exit(1);
 823         }
 824         printf("Switched invoking process to new session keyring %ld\n", keyid);
 825         exit(0);
 826 }
 827
 828 #define CMD(name) { #name, do_##name, name##_desc, name##_help, 0 }
 829 #define _CMD(name) { #name, do_##name, NULL, NULL, CMD_HIDDEN }
 830
 831 const struct cmd_desc cmd_list[] = {
 832         _CMD(help),
 833         CMD(add_key),
 834         CMD(get_policy),
 835         CMD(new_session),
 836         CMD(set_policy),
 837         { NULL, NULL, NULL, NULL, 0 }
 838 };
 839
 840 static void do_help(int argc, char **argv,
 841                     const struct cmd_desc *cmd EXT2FS_ATTR((unused)))
 842 {
 843         const struct cmd_desc *p;
 844
 845         if (argc > 1) {
 846                 for (p = cmd_list; p->cmd_name; p++) {
 847                         if (p->cmd_flags & CMD_HIDDEN)
 848                                 continue;
 849                         if (strcmp(p->cmd_name, argv[1]) == 0) {
 850                                 putc('\n', stdout);
 851                                 fputs("USAGE:\n  ", stdout);
 852                                 fputs(p->cmd_help, stdout);
 853                                 exit(0);
 854                         }
 855                 }
 856                 printf("Unknown command: %s\n\n", argv[1]);
 857         }
 858
 859         fputs("Available commands:\n", stdout);
 860         for (p = cmd_list; p->cmd_name; p++) {
 861                 if (p->cmd_flags & CMD_HIDDEN)
 862                         continue;
 863                 printf("  %-20s %s\n", p->cmd_name, p->cmd_desc);
 864         }
 865         printf("\nTo get more information on a command, "
 866                "type 'e4crypt help cmd'\n");
 867         exit(0);
 868 }
 869
 870 int main(int argc, char *argv[])
 871 {
 872         const struct cmd_desc *cmd;
 873
 874         if (argc < 2)
 875                 do_help(argc, argv, cmd_list);
 876
 877         sigcatcher_setup();
 878         for (cmd = cmd_list; cmd->cmd_name; cmd++) {
 879                 if (strcmp(cmd->cmd_name, argv[1]) == 0) {
 880                         cmd->cmd_func(argc-1, argv+1, cmd);
 881                         exit(0);
 882                 }
 883         }
 884         printf("Unknown command: %s\n\n", argv[1]);
 885         do_help(1, argv, cmd_list);
 886         return 0;
 887 }