| /* vi: set sw=4 ts=4: */ |
| /* mkswap.c - format swap device (Linux v1 only) |
| * |
| * Copyright 2006 Rob Landley <rob@landley.net> |
| * |
| * Licensed under GPL version 2, see file LICENSE in this tarball for details. |
| */ |
| #include "libbb.h" |
| |
| #if ENABLE_SELINUX |
| static void mkswap_selinux_setcontext(int fd, const char *path) |
| { |
| struct stat stbuf; |
| |
| if (!is_selinux_enabled()) |
| return; |
| |
| if (fstat(fd, &stbuf) < 0) |
| bb_perror_msg_and_die("fstat failed"); |
| if (S_ISREG(stbuf.st_mode)) { |
| security_context_t newcon; |
| security_context_t oldcon = NULL; |
| context_t context; |
| |
| if (fgetfilecon(fd, &oldcon) < 0) { |
| if (errno != ENODATA) |
| goto error; |
| if (matchpathcon(path, stbuf.st_mode, &oldcon) < 0) |
| goto error; |
| } |
| context = context_new(oldcon); |
| if (!context || context_type_set(context, "swapfile_t")) |
| goto error; |
| newcon = context_str(context); |
| if (!newcon) |
| goto error; |
| /* fsetfilecon_raw is hidden */ |
| if (strcmp(oldcon, newcon) != 0 && fsetfilecon(fd, newcon) < 0) |
| goto error; |
| if (ENABLE_FEATURE_CLEAN_UP) { |
| context_free(context); |
| freecon(oldcon); |
| } |
| } |
| return; |
| error: |
| bb_perror_msg_and_die("SELinux relabeling failed"); |
| } |
| #else |
| # define mkswap_selinux_setcontext(fd, path) ((void)0) |
| #endif |
| |
| #if ENABLE_FEATURE_MKSWAP_UUID |
| static void mkswap_generate_uuid(uint8_t *buf) |
| { |
| /* http://www.ietf.org/rfc/rfc4122.txt |
| * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 |
| * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| * | time_low | |
| * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| * | time_mid | time_hi_and_version | |
| * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| * |clk_seq_and_variant | node (0-1) | |
| * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| * | node (2-5) | |
| * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| * IOW, uuid has this layout: |
| * uint32_t time_low (big endian) |
| * uint16_t time_mid (big endian) |
| * uint16_t time_hi_and_version (big endian) |
| * version is a 4-bit field: |
| * 1 Time-based |
| * 2 DCE Security, with embedded POSIX UIDs |
| * 3 Name-based (MD5) |
| * 4 Randomly generated |
| * 5 Name-based (SHA-1) |
| * uint16_t clk_seq_and_variant (big endian) |
| * variant is a 3-bit field: |
| * 0xx Reserved, NCS backward compatibility |
| * 10x The variant specified in rfc4122 |
| * 110 Reserved, Microsoft backward compatibility |
| * 111 Reserved for future definition |
| * uint8_t node[6] |
| * |
| * For version 4, these bits are set/cleared: |
| * time_hi_and_version & 0x0fff | 0x4000 |
| * clk_seq_and_variant & 0x3fff | 0x8000 |
| */ |
| pid_t pid; |
| int i; |
| char uuid_string[32]; |
| |
| i = open("/dev/urandom", O_RDONLY); |
| if (i >= 0) { |
| read(i, buf, 16); |
| close(i); |
| } |
| /* Paranoia. /dev/urandom may be missing. |
| * rand() is guaranteed to generate at least [0, 2^15) range, |
| * but lowest bits in some libc are not so "random". */ |
| srand(monotonic_us()); |
| pid = getpid(); |
| while (1) { |
| for (i = 0; i < 16; i++) |
| buf[i] ^= rand() >> 5; |
| if (pid == 0) |
| break; |
| srand(pid); |
| pid = 0; |
| } |
| |
| /* version = 4 */ |
| buf[4 + 2 ] = (buf[4 + 2 ] & 0x0f) | 0x40; |
| /* variant = 10x */ |
| buf[4 + 2 + 2] = (buf[4 + 2 + 2] & 0x3f) | 0x80; |
| |
| bin2hex(uuid_string, (void*) buf, 16); |
| /* f.e. UUID=dfd9c173-be52-4d27-99a5-c34c6c2ff55f */ |
| printf("UUID=%.8s" "-%.4s-%.4s-%.4s-%.12s\n", |
| uuid_string, |
| uuid_string+8, |
| uuid_string+8+4, |
| uuid_string+8+4+4, |
| uuid_string+8+4+4+4 |
| ); |
| } |
| #else |
| # define mkswap_generate_uuid(buf) ((void)0) |
| #endif |
| |
| #if 0 /* from Linux 2.6.23 */ |
| /* |
| * Magic header for a swap area. The first part of the union is |
| * what the swap magic looks like for the old (limited to 128MB) |
| * swap area format, the second part of the union adds - in the |
| * old reserved area - some extra information. Note that the first |
| * kilobyte is reserved for boot loader or disk label stuff... |
| */ |
| union swap_header { |
| struct { |
| char reserved[PAGE_SIZE - 10]; |
| char magic[10]; /* SWAP-SPACE or SWAPSPACE2 */ |
| } magic; |
| struct { |
| char bootbits[1024]; /* Space for disklabel etc. */ |
| __u32 version; /* second kbyte, word 0 */ |
| __u32 last_page; /* 1 */ |
| __u32 nr_badpages; /* 2 */ |
| unsigned char sws_uuid[16]; /* 3,4,5,6 */ |
| unsigned char sws_volume[16]; /* 7,8,9,10 */ |
| __u32 padding[117]; /* 11..127 */ |
| __u32 badpages[1]; /* 128, total 129 32-bit words */ |
| } info; |
| }; |
| #endif |
| |
| #define NWORDS 129 |
| #define hdr ((uint32_t*)(&bb_common_bufsiz1)) |
| |
| struct BUG_bufsiz1_is_too_small { |
| char BUG_bufsiz1_is_too_small[COMMON_BUFSIZE < (NWORDS * 4) ? -1 : 1]; |
| }; |
| |
| /* Stored without terminating NUL */ |
| static const char SWAPSPACE2[sizeof("SWAPSPACE2")-1] ALIGN1 = "SWAPSPACE2"; |
| |
| int mkswap_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
| int mkswap_main(int argc, char **argv) |
| { |
| int fd, pagesize; |
| off_t len; |
| |
| // No options supported. |
| |
| if (argc != 2) bb_show_usage(); |
| |
| // Figure out how big the device is and announce our intentions. |
| |
| fd = xopen(argv[1], O_RDWR); |
| /* fdlength was reported to be unreliable - use seek */ |
| len = xlseek(fd, 0, SEEK_END); |
| #if ENABLE_SELINUX |
| xlseek(fd, 0, SEEK_SET); |
| #endif |
| pagesize = getpagesize(); |
| printf("Setting up swapspace version 1, size = %"OFF_FMT"u bytes\n", |
| len - pagesize); |
| mkswap_selinux_setcontext(fd, argv[1]); |
| |
| // Make a header. hdr is zero-filled so far... |
| hdr[0] = 1; |
| hdr[1] = (len / pagesize) - 1; |
| mkswap_generate_uuid((void*) &hdr[3]); |
| |
| // Write the header. Sync to disk because some kernel versions check |
| // signature on disk (not in cache) during swapon. |
| xlseek(fd, 1024, SEEK_SET); |
| xwrite(fd, hdr, NWORDS * 4); |
| xlseek(fd, pagesize - 10, SEEK_SET); |
| xwrite(fd, SWAPSPACE2, 10); |
| fsync(fd); |
| |
| if (ENABLE_FEATURE_CLEAN_UP) close(fd); |
| |
| return 0; |
| } |