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/*
* Small program to LUKS suspend devices before system suspend
*
* Copyright: (c) 2018 Guilhem Moulin <guilhem@debian.org>
* (c) 2018-2020 Jonas Meurer <jonas@freesources.org>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>
#include <err.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <libcryptsetup.h>
#define SYSFS_POWER_SYNC_ON_SUSPEND "/sys/power/sync_on_suspend"
#define SYSFS_POWER_STATE "/sys/power/state"
void usage() {
printf("Usage: cryptsetup-suspend [-r|--reverse] <blkdev> [<blkdev> ...]\n"
" -r, --reverse process luks devices in reverse order\n\n");
exit(1);
}
/* Calculate free memory (MemAvailable + SwapFree) from /proc/meminfo */
uint32_t get_mem_swap_avail_kb() {
FILE *meminfo = fopen("/proc/meminfo", "r");
if (meminfo == NULL)
err(EXIT_FAILURE, "couldn't open /proc/meminfo");
int mem_avail_kb, swap_free_kb = 0;
char line[256];
while (fgets(line, sizeof(line), meminfo)) {
if (strncmp(line, "MemAvailable", strlen("MemAvailable")) == 0) {
if (sscanf(line, "MemAvailable: %d kB", &mem_avail_kb) != 1)
errx(EXIT_FAILURE, "couldn't read MemAvailable from /proc/meminfo");
} else if (strncmp(line, "SwapFree", strlen("SwapFree")) == 0) {
if (sscanf(line, "SwapFree: %d kB", &swap_free_kb) != 1)
errx(EXIT_FAILURE, "couldn't read SwapFree from /proc/meminfo");
}
}
fclose(meminfo);
uint32_t mem_swap_avail_kb = mem_avail_kb + swap_free_kb;
if (mem_swap_avail_kb == 0)
errx(EXIT_FAILURE, "error reading available memory and swap from /proc/meminfo");
return mem_swap_avail_kb;
}
int main(int argc, char *argv[]) {
int rv = 0;
bool reverse = 0;
int d_size;
bool sync_on_suspend_reset = 0;
FILE *sos = NULL;
/* Process commandline arguments */
if (argc < 2) {
usage();
} else if ((strcmp(argv[1], "-r") == 0) || (strcmp(argv[1], "--reverse") == 0)) {
if (argc < 3)
usage();
reverse = 1;
d_size = argc-2;
} else {
d_size = argc-1;
}
/* Read in devices */
const char *devices[d_size];
if (!reverse) {
for (int i = 0; i < d_size; i++) {
devices[i] = argv[i+1];
}
} else {
for (int i = 0; i < d_size; i++) {
devices[i] = argv[argc-i-1];
}
}
/* Disable sync_on_suspend in Linux kernel
*
* Only available in Linux kernel >= 5.6 */
if (access(SYSFS_POWER_SYNC_ON_SUSPEND, W_OK) < 0) {
if (errno == ENOENT)
warnx("kernel too old, can't disable sync on suspend");
} else {
sos = fopen(SYSFS_POWER_SYNC_ON_SUSPEND, "r+");
if (!sos)
err(EXIT_FAILURE, "couldn't open sysfs file");
int sos_c = fgetc(sos);
if (fgetc(sos) == EOF)
err(EXIT_FAILURE, "couldn't read from file");
if (sos_c == '0') {
/* Already disabled */
} else if (sos_c == '1') {
sync_on_suspend_reset = 1;
if (fputc('0', sos) <= 0)
err(EXIT_FAILURE, "couldn't write to file");
} else {
errx(EXIT_FAILURE, "unexpected value from %s", SYSFS_POWER_SYNC_ON_SUSPEND);
}
fclose(sos);
}
/* Change process priority to -20 (highest) to avoid races between
* the LUKS suspend(s) and the suspend-on-ram. */
if (setpriority(PRIO_PROCESS, 0, -20) == -1)
warn("can't lower process priority to -20");
/* Get memory settings of keyslots from processed LUKS2 devices */
uint32_t argon2i_max_memory_kb = 0;
for (int i = 0; i < d_size; i++) {
struct crypt_device *cd = NULL;
if (crypt_init_by_name(&cd, devices[i])) {
warnx("couldn't init LUKS device %s", devices[i]);
rv = EXIT_FAILURE;
} else {
/* Only LUKS2 devices may use argon2i PBKDF */
if (strcmp(crypt_get_type(cd), CRYPT_LUKS2) != 0)
continue;
int ks_max = crypt_keyslot_max(crypt_get_type(cd));
for (int j = 0; j < ks_max; j++) {
crypt_keyslot_info ki = crypt_keyslot_status(cd, j);
/* Only look at active keyslots */
if (ki != CRYPT_SLOT_ACTIVE && ki != CRYPT_SLOT_ACTIVE_LAST)
continue;
struct crypt_pbkdf_type pbkdf_ki;
if (crypt_keyslot_get_pbkdf(cd, j, &pbkdf_ki) < 0) {
warn("couldn't get PBKDF for keyslot %d of device %s", j, devices[i]);
rv = EXIT_FAILURE;
} else {
if (pbkdf_ki.max_memory_kb > argon2i_max_memory_kb)
argon2i_max_memory_kb = pbkdf_ki.max_memory_kb;
}
}
}
crypt_free(cd);
}
/* Add some more memory to be on the safe side
* TODO: find a reasonable value */
argon2i_max_memory_kb += 2 * 1024; // 2MB
/* Check if we have enough memory available to prevent mlock() from
* triggering the OOM killer. */
uint32_t mem_swap_avail_kb = get_mem_swap_avail_kb();
if (argon2i_max_memory_kb > mem_swap_avail_kb) {
errx(EXIT_FAILURE, "Error: Available memory (%d kb) less than required (%d kb)",
mem_swap_avail_kb, argon2i_max_memory_kb);
}
/* Allocate and lock memory for later usage by LUKS resume in order to
* prevent swapping out after LUKS devices (which might include swap
* storage) have been suspended. */
fprintf(stderr, "Allocating and mlocking memory: %d kb\n", argon2i_max_memory_kb);
char *mem;
if (!(mem = malloc(argon2i_max_memory_kb)))
err(EXIT_FAILURE, "couldn't allocate enough memory");
if (mlock(mem, argon2i_max_memory_kb) == -1)
err(EXIT_FAILURE, "couldn't lock enough memory");
/* Fill the allocated memory to make sure it's really reserved even if
* memory pages are copy-on-write. */
size_t i;
size_t page_size = getpagesize();
for (i = 0; i < argon2i_max_memory_kb; i += page_size)
mem[i] = 0;
/* Do the final filesystem sync since we disabled sync_on_suspend in
* Linux kernel. */
sync();
for (int i = 0; i < d_size; i++) {
struct crypt_device *cd = NULL;
if (crypt_init_by_name(&cd, devices[i]) || crypt_suspend(cd, devices[i])) {
warnx("couldn't suspend LUKS device %s", devices[i]);
rv = EXIT_FAILURE;
}
crypt_free(cd);
}
fprintf(stderr, "Sleeping...\n");
FILE *s = fopen(SYSFS_POWER_STATE, "w");
if (!s)
err(EXIT_FAILURE, "failed to open %s", SYSFS_POWER_STATE);
if (fputs("mem", s) <= 0)
err(EXIT_FAILURE, "couldn't write to %s", SYSFS_POWER_STATE);
fclose(s);
fprintf(stderr, "Resuming...\n");
/* Restore original sync_on_suspend value */
if (sync_on_suspend_reset) {
sos = fopen(SYSFS_POWER_SYNC_ON_SUSPEND, "w");
if (!sos)
err(EXIT_FAILURE, "couldn't open sysfs file");
if (fputc('1', sos) <= 0)
err(EXIT_FAILURE, "couldn't write to file");
fclose(sos);
}
return rv;
}
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