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-rw-r--r--src/shared/hibernate-util.c520
1 files changed, 520 insertions, 0 deletions
diff --git a/src/shared/hibernate-util.c b/src/shared/hibernate-util.c
new file mode 100644
index 0000000..0d215e8
--- /dev/null
+++ b/src/shared/hibernate-util.c
@@ -0,0 +1,520 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/***
+ Copyright © 2018 Dell Inc.
+***/
+
+#include <linux/fs.h>
+#include <linux/magic.h>
+#include <stddef.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "blockdev-util.h"
+#include "btrfs-util.h"
+#include "device-util.h"
+#include "devnum-util.h"
+#include "efivars.h"
+#include "env-util.h"
+#include "errno-util.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "hibernate-util.h"
+#include "log.h"
+#include "parse-util.h"
+#include "path-util.h"
+#include "stat-util.h"
+#include "string-util.h"
+#include "strv.h"
+
+#define HIBERNATION_SWAP_THRESHOLD 0.98
+
+void hibernation_device_done(HibernationDevice *device) {
+ assert(device);
+
+ free(device->path);
+}
+
+int read_fiemap(int fd, struct fiemap **ret) {
+ _cleanup_free_ struct fiemap *fiemap = NULL, *result_fiemap = NULL;
+ struct stat statinfo;
+ uint32_t result_extents = 0;
+ uint64_t fiemap_start = 0, fiemap_length;
+ const size_t n_extra = DIV_ROUND_UP(sizeof(struct fiemap), sizeof(struct fiemap_extent));
+
+ assert(fd >= 0);
+ assert(ret);
+
+ if (fstat(fd, &statinfo) < 0)
+ return log_debug_errno(errno, "Cannot determine file size: %m");
+ if (!S_ISREG(statinfo.st_mode))
+ return -ENOTTY;
+ fiemap_length = statinfo.st_size;
+
+ /* Zero this out in case we run on a file with no extents */
+ fiemap = calloc(n_extra, sizeof(struct fiemap_extent));
+ if (!fiemap)
+ return -ENOMEM;
+
+ result_fiemap = malloc_multiply(n_extra, sizeof(struct fiemap_extent));
+ if (!result_fiemap)
+ return -ENOMEM;
+
+ /* XFS filesystem has incorrect implementation of fiemap ioctl and
+ * returns extents for only one block-group at a time, so we need
+ * to handle it manually, starting the next fiemap call from the end
+ * of the last extent
+ */
+ while (fiemap_start < fiemap_length) {
+ *fiemap = (struct fiemap) {
+ .fm_start = fiemap_start,
+ .fm_length = fiemap_length,
+ .fm_flags = FIEMAP_FLAG_SYNC,
+ };
+
+ /* Find out how many extents there are */
+ if (ioctl(fd, FS_IOC_FIEMAP, fiemap) < 0)
+ return log_debug_errno(errno, "Failed to read extents: %m");
+
+ /* Nothing to process */
+ if (fiemap->fm_mapped_extents == 0)
+ break;
+
+ /* Resize fiemap to allow us to read in the extents, result fiemap has to hold all
+ * the extents for the whole file. Add space for the initial struct fiemap. */
+ if (!greedy_realloc0((void**) &fiemap, n_extra + fiemap->fm_mapped_extents, sizeof(struct fiemap_extent)))
+ return -ENOMEM;
+
+ fiemap->fm_extent_count = fiemap->fm_mapped_extents;
+ fiemap->fm_mapped_extents = 0;
+
+ if (ioctl(fd, FS_IOC_FIEMAP, fiemap) < 0)
+ return log_debug_errno(errno, "Failed to read extents: %m");
+
+ /* Resize result_fiemap to allow us to copy in the extents */
+ if (!greedy_realloc((void**) &result_fiemap,
+ n_extra + result_extents + fiemap->fm_mapped_extents, sizeof(struct fiemap_extent)))
+ return -ENOMEM;
+
+ memcpy(result_fiemap->fm_extents + result_extents,
+ fiemap->fm_extents,
+ sizeof(struct fiemap_extent) * fiemap->fm_mapped_extents);
+
+ result_extents += fiemap->fm_mapped_extents;
+
+ /* Highly unlikely that it is zero */
+ if (_likely_(fiemap->fm_mapped_extents > 0)) {
+ uint32_t i = fiemap->fm_mapped_extents - 1;
+
+ fiemap_start = fiemap->fm_extents[i].fe_logical +
+ fiemap->fm_extents[i].fe_length;
+
+ if (fiemap->fm_extents[i].fe_flags & FIEMAP_EXTENT_LAST)
+ break;
+ }
+ }
+
+ memcpy(result_fiemap, fiemap, sizeof(struct fiemap));
+ result_fiemap->fm_mapped_extents = result_extents;
+ *ret = TAKE_PTR(result_fiemap);
+ return 0;
+}
+
+static int read_resume_config(dev_t *ret_devno, uint64_t *ret_offset) {
+ _cleanup_free_ char *devno_str = NULL, *offset_str = NULL;
+ uint64_t offset;
+ dev_t devno;
+ int r;
+
+ assert(ret_devno);
+ assert(ret_offset);
+
+ r = read_one_line_file("/sys/power/resume", &devno_str);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to read /sys/power/resume: %m");
+
+ r = parse_devnum(devno_str, &devno);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to parse /sys/power/resume devno '%s': %m", devno_str);
+
+ r = read_one_line_file("/sys/power/resume_offset", &offset_str);
+ if (r == -ENOENT) {
+ log_debug_errno(r, "Kernel does not expose resume_offset, skipping.");
+ offset = UINT64_MAX;
+ } else if (r < 0)
+ return log_debug_errno(r, "Failed to read /sys/power/resume_offset: %m");
+ else {
+ r = safe_atou64(offset_str, &offset);
+ if (r < 0)
+ return log_debug_errno(r,
+ "Failed to parse /sys/power/resume_offset '%s': %m", offset_str);
+ }
+
+ if (devno == 0 && offset > 0 && offset != UINT64_MAX)
+ return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+ "Found resume_offset=%" PRIu64 " but resume= is unset, refusing.", offset);
+
+ *ret_devno = devno;
+ *ret_offset = offset;
+
+ return 0;
+}
+
+/* entry in /proc/swaps */
+typedef struct SwapEntry {
+ char *path;
+ bool swapfile;
+
+ uint64_t size;
+ uint64_t used;
+ int priority;
+
+ /* Not present in original entry */
+ dev_t devno;
+ uint64_t offset;
+} SwapEntry;
+
+typedef struct SwapEntries {
+ SwapEntry *swaps;
+ size_t n_swaps;
+} SwapEntries;
+
+static void swap_entry_done(SwapEntry *entry) {
+ assert(entry);
+
+ free(entry->path);
+}
+
+static void swap_entries_done(SwapEntries *entries) {
+ assert(entries);
+
+ FOREACH_ARRAY(i, entries->swaps, entries->n_swaps)
+ swap_entry_done(i);
+
+ free(entries->swaps);
+}
+
+static int swap_entry_get_resume_config(SwapEntry *swap) {
+ _cleanup_close_ int fd = -EBADF;
+ uint64_t offset_raw;
+ struct stat st;
+ int r;
+
+ assert(swap);
+ assert(swap->path);
+
+ fd = open(swap->path, O_RDONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
+ if (fd < 0)
+ return -errno;
+
+ if (fstat(fd, &st) < 0)
+ return -errno;
+
+ if (!swap->swapfile) {
+ if (!S_ISBLK(st.st_mode))
+ return -ENOTBLK;
+
+ swap->devno = st.st_rdev;
+ swap->offset = 0;
+ return 0;
+ }
+
+ r = stat_verify_regular(&st);
+ if (r < 0)
+ return r;
+
+ r = get_block_device_fd(fd, &swap->devno);
+ if (r < 0)
+ return r;
+
+ r = fd_is_fs_type(fd, BTRFS_SUPER_MAGIC);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to check if swap file '%s' is on Btrfs: %m", swap->path);
+ if (r > 0) {
+ r = btrfs_get_file_physical_offset_fd(fd, &offset_raw);
+ if (r < 0)
+ return r;
+ } else {
+ _cleanup_free_ struct fiemap *fiemap = NULL;
+
+ r = read_fiemap(fd, &fiemap);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to read extent map for swap file '%s': %m", swap->path);
+
+ offset_raw = fiemap->fm_extents[0].fe_physical;
+ }
+
+ swap->offset = offset_raw / page_size();
+ return 0;
+}
+
+static int read_swap_entries(SwapEntries *ret) {
+ _cleanup_(swap_entries_done) SwapEntries entries = {};
+ _cleanup_fclose_ FILE *f = NULL;
+
+ assert(ret);
+
+ f = fopen("/proc/swaps", "re");
+ if (!f)
+ return log_debug_errno(errno, "Failed to open /proc/swaps: %m");
+
+ /* Remove header */
+ (void) fscanf(f, "%*s %*s %*s %*s %*s\n");
+
+ for (unsigned i = 1;; i++) {
+ _cleanup_(swap_entry_done) SwapEntry swap = {};
+ _cleanup_free_ char *type = NULL;
+ int k;
+
+ k = fscanf(f,
+ "%ms " /* device/file path */
+ "%ms " /* type of swap */
+ "%" PRIu64 /* swap size */
+ "%" PRIu64 /* used */
+ "%i" /* priority */
+ "\n",
+ &swap.path, &type, &swap.size, &swap.used, &swap.priority);
+ if (k == EOF)
+ break;
+ if (k != 5)
+ return log_debug_errno(SYNTHETIC_ERRNO(EIO), "Failed to parse /proc/swaps line %u.", i);
+
+ if (streq(type, "file")) {
+ if (endswith(swap.path, "\\040(deleted)")) {
+ log_debug("Swap file '%s' has been deleted, ignoring.", swap.path);
+ continue;
+ }
+
+ swap.swapfile = true;
+
+ } else if (streq(type, "partition")) {
+ const char *node;
+
+ node = path_startswith(swap.path, "/dev/");
+ if (node && startswith(node, "zram")) {
+ log_debug("Swap partition '%s' is a zram device, ignoring.", swap.path);
+ continue;
+ }
+
+ swap.swapfile = false;
+
+ } else {
+ log_debug("Swap type %s is not supported for hibernation, ignoring device: %s",
+ type, swap.path);
+ continue;
+ }
+
+ if (!GREEDY_REALLOC(entries.swaps, entries.n_swaps + 1))
+ return log_oom_debug();
+
+ entries.swaps[entries.n_swaps++] = TAKE_STRUCT(swap);
+ }
+
+ *ret = TAKE_STRUCT(entries);
+ return 0;
+}
+
+/* Attempt to find a suitable device for hibernation by parsing /proc/swaps, /sys/power/resume, and
+ * /sys/power/resume_offset.
+ *
+ * Beware:
+ * Never use a device or file that hasn't been somehow specified by a user who would also be entrusted
+ * with full system memory access (for example via /sys/power/resume) or that isn't an already active
+ * swap area! Otherwise various security attacks might become possible, for example an attacker could
+ * silently attach such a device and circumvent full disk encryption when it would be automatically used
+ * for hibernation. Also, having a swap area on top of encryption is not per se enough to protect from all
+ * such attacks.
+ *
+ * Returns:
+ * 1 - Values are set in /sys/power/resume and /sys/power/resume_offset.
+ *
+ * 0 - No values are set in /sys/power/resume and /sys/power/resume_offset.
+ * ret will represent the highest priority swap with most remaining space discovered in /proc/swaps.
+ *
+ * Negative value in the case of error */
+int find_suitable_hibernation_device_full(HibernationDevice *ret_device, uint64_t *ret_size, uint64_t *ret_used) {
+ _cleanup_(swap_entries_done) SwapEntries entries = {};
+ SwapEntry *entry = NULL;
+ uint64_t resume_config_offset;
+ dev_t resume_config_devno;
+ int r;
+
+ assert(!ret_size == !ret_used);
+
+ r = read_resume_config(&resume_config_devno, &resume_config_offset);
+ if (r < 0)
+ return r;
+
+ r = read_swap_entries(&entries);
+ if (r < 0)
+ return r;
+ if (entries.n_swaps == 0)
+ return log_debug_errno(SYNTHETIC_ERRNO(ENOSPC), "No swap space available for hibernation.");
+
+ FOREACH_ARRAY(swap, entries.swaps, entries.n_swaps) {
+ r = swap_entry_get_resume_config(swap);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to get devno and offset for swap '%s': %m", swap->path);
+ if (swap->devno == 0) {
+ assert(swap->swapfile);
+
+ log_debug("Swap file '%s' is not backed by block device, ignoring: %m", swap->path);
+ continue;
+ }
+
+ if (resume_config_devno > 0) {
+ if (swap->devno == resume_config_devno &&
+ (!swap->swapfile || resume_config_offset == UINT64_MAX || swap->offset == resume_config_offset)) {
+ /* /sys/power/resume (resume=) is set, and the calculated swap file offset
+ * matches with /sys/power/resume_offset. If /sys/power/resume_offset is not
+ * exposed, we can't do proper check anyway, so use the found swap file too. */
+ entry = swap;
+ break;
+ }
+
+ /* If resume= is set, don't try to use other swap spaces. */
+ continue;
+ }
+
+ if (!entry ||
+ swap->priority > entry->priority ||
+ swap->size - swap->used > entry->size - entry->used)
+ entry = swap;
+ }
+
+ if (!entry) {
+ /* No need to check n_swaps == 0, since it's rejected early */
+ assert(resume_config_devno > 0);
+ return log_debug_errno(SYNTHETIC_ERRNO(ENOSPC), "Cannot find swap entry corresponding to /sys/power/resume.");
+ }
+
+ if (ret_device) {
+ char *path;
+
+ if (entry->swapfile) {
+ r = device_path_make_canonical(S_IFBLK, entry->devno, &path);
+ if (r < 0)
+ return log_debug_errno(r,
+ "Failed to format canonical device path for devno '" DEVNUM_FORMAT_STR "': %m",
+ DEVNUM_FORMAT_VAL(entry->devno));
+ } else
+ path = TAKE_PTR(entry->path);
+
+ *ret_device = (HibernationDevice) {
+ .devno = entry->devno,
+ .offset = entry->offset,
+ .path = path,
+ };
+ }
+
+ if (ret_size) {
+ *ret_size = entry->size;
+ *ret_used = entry->used;
+ }
+
+ return resume_config_devno > 0;
+}
+
+static int get_proc_meminfo_active(unsigned long long *ret) {
+ _cleanup_free_ char *active_str = NULL;
+ unsigned long long active;
+ int r;
+
+ assert(ret);
+
+ r = get_proc_field("/proc/meminfo", "Active(anon)", WHITESPACE, &active_str);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to retrieve Active(anon) from /proc/meminfo: %m");
+
+ r = safe_atollu(active_str, &active);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to parse Active(anon) '%s' from /proc/meminfo: %m", active_str);
+
+ *ret = active;
+ return 0;
+}
+
+int hibernation_is_safe(void) {
+ unsigned long long active;
+ uint64_t size, used;
+ bool resume_set, bypass_space_check;
+ int r;
+
+ bypass_space_check = getenv_bool("SYSTEMD_BYPASS_HIBERNATION_MEMORY_CHECK") > 0;
+
+ r = find_suitable_hibernation_device_full(NULL, &size, &used);
+ if (r == -ENOSPC && bypass_space_check)
+ /* If we don't have any available swap space at all, and SYSTEMD_BYPASS_HIBERNATION_MEMORY_CHECK
+ * is set, skip all remaining checks since we can't do that properly anyway. It is quite
+ * possible that the user is using a setup similar to #30083. When we actually perform
+ * hibernation in sleep.c we'll check everything again. */
+ return 0;
+ if (r < 0)
+ return r;
+ resume_set = r > 0;
+
+ if (!resume_set && !is_efi_boot())
+ return log_debug_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE),
+ "Not running on EFI and resume= is not set. Hibernation is not safe.");
+
+ if (bypass_space_check)
+ return true;
+
+ r = get_proc_meminfo_active(&active);
+ if (r < 0)
+ return r;
+
+ r = active <= (size - used) * HIBERNATION_SWAP_THRESHOLD;
+ log_debug("Detected %s swap for hibernation: Active(anon)=%llu kB, size=%" PRIu64 " kB, used=%" PRIu64 " kB, threshold=%.2g%%",
+ r ? "enough" : "not enough", active, size, used, 100 * HIBERNATION_SWAP_THRESHOLD);
+ if (!r)
+ return -ENOSPC;
+
+ return resume_set;
+}
+
+int write_resume_config(dev_t devno, uint64_t offset, const char *device) {
+ char offset_str[DECIMAL_STR_MAX(uint64_t)];
+ _cleanup_free_ char *path = NULL;
+ const char *devno_str;
+ int r;
+
+ devno_str = FORMAT_DEVNUM(devno);
+ xsprintf(offset_str, "%" PRIu64, offset);
+
+ if (!device) {
+ r = device_path_make_canonical(S_IFBLK, devno, &path);
+ if (r < 0)
+ return log_error_errno(r,
+ "Failed to format canonical device path for devno '" DEVNUM_FORMAT_STR "': %m",
+ DEVNUM_FORMAT_VAL(devno));
+ device = path;
+ }
+
+ /* We write the offset first since it's safer. Note that this file is only available in 4.17+, so
+ * fail gracefully if it doesn't exist and we're only overwriting it with 0. */
+ r = write_string_file("/sys/power/resume_offset", offset_str, WRITE_STRING_FILE_DISABLE_BUFFER);
+ if (r == -ENOENT) {
+ if (offset != 0)
+ return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP),
+ "Can't configure hibernation offset %" PRIu64 ", kernel does not support /sys/power/resume_offset. Refusing.",
+ offset);
+
+ log_warning_errno(r, "/sys/power/resume_offset is unavailable, skipping writing swap file offset.");
+ } else if (r < 0)
+ return log_error_errno(r,
+ "Failed to write swap file offset %s to /sys/power/resume_offset for device '%s': %m",
+ offset_str, device);
+ else
+ log_debug("Wrote resume_offset=%s for device '%s' to /sys/power/resume_offset.",
+ offset_str, device);
+
+ r = write_string_file("/sys/power/resume", devno_str, WRITE_STRING_FILE_DISABLE_BUFFER);
+ if (r < 0)
+ return log_error_errno(r,
+ "Failed to write device '%s' (%s) to /sys/power/resume: %m",
+ device, devno_str);
+ log_debug("Wrote resume=%s for device '%s' to /sys/power/resume.", devno_str, device);
+
+ return 0;
+}
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