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https://github.com/sheumann/hush.git
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137 lines
3.5 KiB
C
137 lines
3.5 KiB
C
/* vi: set sw=4 ts=4: */
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/* mkswap.c - format swap device (Linux v1 only)
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*
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* Copyright 2006 Rob Landley <rob@landley.net>
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*
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* Licensed under GPL version 2, see file LICENSE in this tarball for details.
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*/
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#include "libbb.h"
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#if ENABLE_SELINUX
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static void mkswap_selinux_setcontext(int fd, const char *path)
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{
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struct stat stbuf;
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if (!is_selinux_enabled())
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return;
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if (fstat(fd, &stbuf) < 0)
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bb_perror_msg_and_die("fstat failed");
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if (S_ISREG(stbuf.st_mode)) {
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security_context_t newcon;
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security_context_t oldcon = NULL;
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context_t context;
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if (fgetfilecon(fd, &oldcon) < 0) {
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if (errno != ENODATA)
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goto error;
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if (matchpathcon(path, stbuf.st_mode, &oldcon) < 0)
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goto error;
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}
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context = context_new(oldcon);
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if (!context || context_type_set(context, "swapfile_t"))
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goto error;
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newcon = context_str(context);
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if (!newcon)
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goto error;
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/* fsetfilecon_raw is hidden */
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if (strcmp(oldcon, newcon) != 0 && fsetfilecon(fd, newcon) < 0)
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goto error;
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if (ENABLE_FEATURE_CLEAN_UP) {
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context_free(context);
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freecon(oldcon);
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}
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}
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return;
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error:
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bb_perror_msg_and_die("SELinux relabeling failed");
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}
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#else
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# define mkswap_selinux_setcontext(fd, path) ((void)0)
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#endif
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/* from Linux 2.6.23 */
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/*
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* Magic header for a swap area. ... Note that the first
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* kilobyte is reserved for boot loader or disk label stuff.
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*/
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struct swap_header_v1 {
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/* char bootbits[1024]; Space for disklabel etc. */
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uint32_t version; /* second kbyte, word 0 */
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uint32_t last_page; /* 1 */
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uint32_t nr_badpages; /* 2 */
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char sws_uuid[16]; /* 3,4,5,6 */
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char sws_volume[16]; /* 7,8,9,10 */
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uint32_t padding[117]; /* 11..127 */
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uint32_t badpages[1]; /* 128 */
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/* total 129 32-bit words in 2nd kilobyte */
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} FIX_ALIASING;
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#define NWORDS 129
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#define hdr ((struct swap_header_v1*)bb_common_bufsiz1)
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struct BUG_sizes {
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char swap_header_v1_wrong[sizeof(*hdr) != (NWORDS * 4) ? -1 : 1];
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char bufsiz1_is_too_small[COMMON_BUFSIZE < (NWORDS * 4) ? -1 : 1];
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};
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/* Stored without terminating NUL */
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static const char SWAPSPACE2[sizeof("SWAPSPACE2")-1] ALIGN1 = "SWAPSPACE2";
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int mkswap_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int mkswap_main(int argc UNUSED_PARAM, char **argv)
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{
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int fd;
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unsigned pagesize;
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off_t len;
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const char *label = "";
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opt_complementary = "-1"; /* at least one param */
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/* TODO: -p PAGESZ, -U UUID */
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getopt32(argv, "L:", &label);
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argv += optind;
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fd = xopen(argv[0], O_WRONLY);
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/* Figure out how big the device is */
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len = get_volume_size_in_bytes(fd, argv[1], 1024, /*extend:*/ 1);
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pagesize = getpagesize();
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len -= pagesize;
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/* Announce our intentions */
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printf("Setting up swapspace version 1, size = %"OFF_FMT"u bytes\n", len);
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mkswap_selinux_setcontext(fd, argv[0]);
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/* Make a header. hdr is zero-filled so far... */
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hdr->version = 1;
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hdr->last_page = (uoff_t)len / pagesize;
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if (ENABLE_FEATURE_MKSWAP_UUID) {
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char uuid_string[32];
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generate_uuid((void*)hdr->sws_uuid);
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bin2hex(uuid_string, hdr->sws_uuid, 16);
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/* f.e. UUID=dfd9c173-be52-4d27-99a5-c34c6c2ff55f */
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printf("UUID=%.8s" "-%.4s-%.4s-%.4s-%.12s\n",
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uuid_string,
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uuid_string+8,
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uuid_string+8+4,
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uuid_string+8+4+4,
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uuid_string+8+4+4+4
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);
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}
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safe_strncpy(hdr->sws_volume, label, 16);
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/* Write the header. Sync to disk because some kernel versions check
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* signature on disk (not in cache) during swapon. */
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xlseek(fd, 1024, SEEK_SET);
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xwrite(fd, hdr, NWORDS * 4);
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xlseek(fd, pagesize - 10, SEEK_SET);
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xwrite(fd, SWAPSPACE2, 10);
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fsync(fd);
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if (ENABLE_FEATURE_CLEAN_UP)
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close(fd);
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return 0;
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}
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