| 1 | /* vi: set sw=4 ts=4: */
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| 2 | /* mkswap.c - format swap device (Linux v1 only)
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| 3 | *
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| 4 | * Copyright 2006 Rob Landley <rob@landley.net>
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| 5 | *
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| 6 | * Licensed under GPLv2, see file LICENSE in this source tree.
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| 7 | */
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| 8 |
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| 9 | //usage:#define mkswap_trivial_usage
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| 10 | //usage: "[-L LBL] BLOCKDEV [KBYTES]"
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| 11 | //usage:#define mkswap_full_usage "\n\n"
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| 12 | //usage: "Prepare BLOCKDEV to be used as swap partition\n"
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| 13 | //usage: "\n -L LBL Label"
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| 14 |
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| 15 | #include "libbb.h"
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| 16 |
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| 17 | #if ENABLE_SELINUX
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| 18 | static void mkswap_selinux_setcontext(int fd, const char *path)
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| 19 | {
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| 20 | struct stat stbuf;
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| 21 |
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| 22 | if (!is_selinux_enabled())
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| 23 | return;
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| 24 |
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| 25 | xfstat(fd, &stbuf, path);
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| 26 | if (S_ISREG(stbuf.st_mode)) {
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| 27 | security_context_t newcon;
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| 28 | security_context_t oldcon = NULL;
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| 29 | context_t context;
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| 30 |
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| 31 | if (fgetfilecon(fd, &oldcon) < 0) {
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| 32 | if (errno != ENODATA)
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| 33 | goto error;
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| 34 | if (matchpathcon(path, stbuf.st_mode, &oldcon) < 0)
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| 35 | goto error;
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| 36 | }
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| 37 | context = context_new(oldcon);
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| 38 | if (!context || context_type_set(context, "swapfile_t"))
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| 39 | goto error;
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| 40 | newcon = context_str(context);
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| 41 | if (!newcon)
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| 42 | goto error;
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| 43 | /* fsetfilecon_raw is hidden */
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| 44 | if (strcmp(oldcon, newcon) != 0 && fsetfilecon(fd, newcon) < 0)
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| 45 | goto error;
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| 46 | if (ENABLE_FEATURE_CLEAN_UP) {
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| 47 | context_free(context);
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| 48 | freecon(oldcon);
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| 49 | }
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| 50 | }
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| 51 | return;
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| 52 | error:
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| 53 | bb_perror_msg_and_die("SELinux relabeling failed");
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| 54 | }
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| 55 | #else
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| 56 | # define mkswap_selinux_setcontext(fd, path) ((void)0)
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| 57 | #endif
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| 58 |
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| 59 | /* from Linux 2.6.23 */
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| 60 | /*
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| 61 | * Magic header for a swap area. ... Note that the first
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| 62 | * kilobyte is reserved for boot loader or disk label stuff.
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| 63 | */
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| 64 | struct swap_header_v1 {
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| 65 | /* char bootbits[1024]; Space for disklabel etc. */
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| 66 | uint32_t version; /* second kbyte, word 0 */
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| 67 | uint32_t last_page; /* 1 */
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| 68 | uint32_t nr_badpages; /* 2 */
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| 69 | char sws_uuid[16]; /* 3,4,5,6 */
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| 70 | char sws_volume[16]; /* 7,8,9,10 */
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| 71 | uint32_t padding[117]; /* 11..127 */
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| 72 | uint32_t badpages[1]; /* 128 */
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| 73 | /* total 129 32-bit words in 2nd kilobyte */
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| 74 | } FIX_ALIASING;
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| 75 |
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| 76 | #define NWORDS 129
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| 77 | #define hdr ((struct swap_header_v1*)bb_common_bufsiz1)
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| 78 |
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| 79 | struct BUG_sizes {
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| 80 | char swap_header_v1_wrong[sizeof(*hdr) != (NWORDS * 4) ? -1 : 1];
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| 81 | char bufsiz1_is_too_small[COMMON_BUFSIZE < (NWORDS * 4) ? -1 : 1];
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| 82 | };
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| 83 |
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| 84 | /* Stored without terminating NUL */
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| 85 | static const char SWAPSPACE2[sizeof("SWAPSPACE2")-1] ALIGN1 = "SWAPSPACE2";
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| 86 |
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| 87 | int mkswap_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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| 88 | int mkswap_main(int argc UNUSED_PARAM, char **argv)
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| 89 | {
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| 90 | int fd;
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| 91 | unsigned pagesize;
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| 92 | off_t len;
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| 93 | const char *label = "";
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| 94 |
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| 95 | opt_complementary = "-1"; /* at least one param */
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| 96 | /* TODO: -p PAGESZ, -U UUID */
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| 97 | getopt32(argv, "L:", &label);
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| 98 | argv += optind;
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| 99 |
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| 100 | fd = xopen(argv[0], O_WRONLY);
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| 101 |
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| 102 | /* Figure out how big the device is */
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| 103 | len = get_volume_size_in_bytes(fd, argv[1], 1024, /*extend:*/ 1);
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| 104 | pagesize = getpagesize();
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| 105 | len -= pagesize;
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| 106 |
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| 107 | /* Announce our intentions */
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| 108 | printf("Setting up swapspace version 1, size = %"OFF_FMT"u bytes\n", len);
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| 109 | mkswap_selinux_setcontext(fd, argv[0]);
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| 110 |
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| 111 | /* hdr is zero-filled so far. Clear the first kbyte, or else
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| 112 | * mkswap-ing former FAT partition does NOT erase its signature.
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| 113 | *
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| 114 | * util-linux-ng 2.17.2 claims to erase it only if it does not see
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| 115 | * a partition table and is not run on whole disk. -f forces it.
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| 116 | */
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| 117 | xwrite(fd, hdr, 1024);
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| 118 |
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| 119 | /* Fill the header. */
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| 120 | hdr->version = 1;
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| 121 | hdr->last_page = (uoff_t)len / pagesize;
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| 122 |
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| 123 | if (ENABLE_FEATURE_MKSWAP_UUID) {
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| 124 | char uuid_string[32];
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| 125 | generate_uuid((void*)hdr->sws_uuid);
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| 126 | bin2hex(uuid_string, hdr->sws_uuid, 16);
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| 127 | /* f.e. UUID=dfd9c173-be52-4d27-99a5-c34c6c2ff55f */
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| 128 | printf("UUID=%.8s" "-%.4s-%.4s-%.4s-%.12s\n",
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| 129 | uuid_string,
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| 130 | uuid_string+8,
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| 131 | uuid_string+8+4,
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| 132 | uuid_string+8+4+4,
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| 133 | uuid_string+8+4+4+4
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| 134 | );
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| 135 | }
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| 136 | safe_strncpy(hdr->sws_volume, label, 16);
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| 137 |
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| 138 | /* Write the header. Sync to disk because some kernel versions check
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| 139 | * signature on disk (not in cache) during swapon. */
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| 140 | xwrite(fd, hdr, NWORDS * 4);
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| 141 | xlseek(fd, pagesize - 10, SEEK_SET);
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| 142 | xwrite(fd, SWAPSPACE2, 10);
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| 143 | fsync(fd);
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| 144 |
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| 145 | if (ENABLE_FEATURE_CLEAN_UP)
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| 146 | close(fd);
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| 147 |
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| 148 | return 0;
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| 149 | }
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