Re: [PATCH 3/4][RFC v2] PM / Hibernate: Encrypt the snapshot pages before submitted to the block device

Yu Chen
2018-07-19T05:26:49Z

Cc linux-kernel@vger.kernel.org and linux-crypto@vger.kernel.org

On Thu, Jul 19, 2018 at 12:40:14AM +0800, Chen Yu wrote:
> This is the core modification to encrypt the hibernation image.
> It leverages the helper functions to encrypt the page data before
> they are submitted to the block device. Besides, for the case of
> hibernation compression, the data are firstly compressed and
> then encrypted, and vice versa for the resume process.
>
> There is also another solution suggested by Lee, Chun-Yi to
> re-traverse the snapshot image at one time and write them either
> to disk or exposed to user space. In that way if the snapshot
> image can be encrypted and authentication, then the uswsusp
> interface is available for userspace, kernel does not need to lock
> it down. The only disadvantages are re-traversing large number of
> pages in snapshot might bring overhead and makes snapshot logic
> a little coupling with crypto logic.
>
> Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Cc: Pavel Machek <pavel@ucw.cz>
> Cc: Len Brown <len.brown@intel.com>
> Cc: "Lee, Chun-Yi" <jlee@suse.com>
> Cc: Eric Biggers <ebiggers@google.com>
> Cc: "Theodore Ts'o" <tytso@mit.edu>
> Cc: Stephan Mueller <smueller@chronox.de>
> Cc: Denis Kenzior <denkenz@gmail.com>
> Cc: linux-pm@vger.kernel.org
> Signed-off-by: Chen Yu <yu.c.chen@intel.com>
> ---
> kernel/power/power.h | 23 +++++++
> kernel/power/swap.c | 182 ++++++++++++++++++++++++++++++++++++++++++++++++---
> 2 files changed, 197 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/power/power.h b/kernel/power/power.h
> index ba3b24c..b8ddc05 100644
> --- a/kernel/power/power.h
> +++ b/kernel/power/power.h
> @@ -109,8 +109,30 @@ struct hibernation_crypto {
>
> extern void hibernation_set_crypto_ops(
> const struct hibernation_crypto_ops *ops);
> +
> +/**
> + * get_crypto_cmd - Get the crypto command.
> + * @suspend: In suspend.
> + * @last_page: If this is the last page. For signature's
> + * hash update/final checking.
> + */
> +static inline unsigned int get_crypto_cmd(bool suspend,
> + bool last_page)
> +{
> + /* TODO: signature support */
> + if (suspend) {
> + return CMD_ENCRYPT;
> + } else {
> + return CMD_DECRYPT;
> + }
> +}
> #else
> #define HIBERNATE_MAX_SALT_BYTES 0
> +static inline unsigned int get_crypto_cmd(bool suspend,
> + bool last_page)
> +{
> + return -EINVAL;
> +}
> #endif
>
> #else /* !CONFIG_HIBERNATION */
> @@ -214,6 +236,7 @@ extern int swsusp_swap_in_use(void);
> #define SF_PLATFORM_MODE 1
> #define SF_NOCOMPRESS_MODE 2
> #define SF_CRC32_MODE 4
> +#define SF_CRYPTO_MODE 8
>
> /* kernel/power/hibernate.c */
> extern int swsusp_check(void);
> diff --git a/kernel/power/swap.c b/kernel/power/swap.c
> index c2bcf97..4b36fb7 100644
> --- a/kernel/power/swap.c
> +++ b/kernel/power/swap.c
> @@ -102,14 +102,16 @@ struct swap_map_handle {
> unsigned int k;
> unsigned long reqd_free_pages;
> u32 crc32;
> + bool crypto;
> };
>
> struct swsusp_header {
> char reserved[PAGE_SIZE - 20 - sizeof(sector_t) - sizeof(int) -
> - sizeof(u32)];
> + sizeof(u32) - HIBERNATE_MAX_SALT_BYTES];
> u32 crc32;
> sector_t image;
> unsigned int flags; /* Flags to pass to the "boot" kernel */
> + char salt[HIBERNATE_MAX_SALT_BYTES];
> char orig_sig[10];
> char sig[10];
> } __packed;
> @@ -318,6 +320,10 @@ static int mark_swapfiles(struct swap_map_handle *handle, unsigned int flags)
> swsusp_header->flags = flags;
> if (flags & SF_CRC32_MODE)
> swsusp_header->crc32 = handle->crc32;
> + if (handle->crypto) {
> + swsusp_header->flags |= SF_CRYPTO_MODE;
> + hibernation_crypto_save((void *)swsusp_header->salt);
> + }
> error = hib_submit_io(REQ_OP_WRITE, REQ_SYNC,
> swsusp_resume_block, swsusp_header, NULL);
> } else {
> @@ -536,10 +542,12 @@ static int save_image(struct swap_map_handle *handle,
> unsigned int m;
> int ret;
> int nr_pages;
> + int crypto_page_idx;
> int err2;
> struct hib_bio_batch hb;
> ktime_t start;
> ktime_t stop;
> + void *tmp = NULL, *crypt_buf = NULL;
>
> hib_init_batch(&hb);
>
> @@ -549,12 +557,36 @@ static int save_image(struct swap_map_handle *handle,
> if (!m)
> m = 1;
> nr_pages = 0;
> + crypto_page_idx = 0;
> + /* Allocate temporary buffer for crypto. */
> + if (handle->crypto) {
> + crypt_buf = (void *)get_zeroed_page(GFP_KERNEL);
> + if (!crypt_buf)
> + return -ENOMEM;
> + }
> +
> start = ktime_get();
> while (1) {
> ret = snapshot_read_next(snapshot);
> if (ret <= 0)
> break;
> - ret = swap_write_page(handle, data_of(*snapshot), &hb);
> + tmp = data_of(*snapshot);
> + if (handle->crypto) {
> + /* Encryption before submit_io.*/
> + ret = hibernation_crypto_data(data_of(*snapshot),
> + PAGE_SIZE,
> + crypt_buf,
> + PAGE_SIZE,
> + get_crypto_cmd(true,
> + (crypto_page_idx ==
> + (nr_to_write - 1))),
> + crypto_page_idx);
> + if (ret)
> + goto out;
> + crypto_page_idx++;
> + tmp = crypt_buf;
> + }
> + ret = swap_write_page(handle, tmp, &hb);
> if (ret)
> break;
> if (!(nr_pages % m))
> @@ -569,6 +601,9 @@ static int save_image(struct swap_map_handle *handle,
> if (!ret)
> pr_info("Image saving done\n");
> swsusp_show_speed(start, stop, nr_to_write, "Wrote");
> + out:
> + if (crypt_buf)
> + free_page((unsigned long)crypt_buf);
> return ret;
> }
>
> @@ -672,6 +707,7 @@ static int save_image_lzo(struct swap_map_handle *handle,
> unsigned int m;
> int ret = 0;
> int nr_pages;
> + int crypto_page_idx;
> int err2;
> struct hib_bio_batch hb;
> ktime_t start;
> @@ -767,6 +803,7 @@ static int save_image_lzo(struct swap_map_handle *handle,
> if (!m)
> m = 1;
> nr_pages = 0;
> + crypto_page_idx = 0;
> start = ktime_get();
> for (;;) {
> for (thr = 0; thr < nr_threads; thr++) {
> @@ -835,7 +872,28 @@ static int save_image_lzo(struct swap_map_handle *handle,
> for (off = 0;
> off < LZO_HEADER + data[thr].cmp_len;
> off += PAGE_SIZE) {
> - memcpy(page, data[thr].cmp + off, PAGE_SIZE);
> + if (handle->crypto) {
> + /*
> + * Encrypt the compressed data
> + * before we write them to the
> + * block device.
> + */
> + ret = hibernation_crypto_data(
> + data[thr].cmp + off,
> + PAGE_SIZE,
> + page,
> + PAGE_SIZE,
> + get_crypto_cmd(true,
> + (crypto_page_idx ==
> + (nr_to_write - 1))),
> + crypto_page_idx);
> + if (ret)
> + goto out_finish;
> + crypto_page_idx++;
> + } else {
> + memcpy(page, data[thr].cmp + off,
> + PAGE_SIZE);
> + }
>
> ret = swap_write_page(handle, page, &hb);
> if (ret)
> @@ -909,6 +967,7 @@ int swsusp_write(unsigned int flags)
> int error;
>
> pages = snapshot_get_image_size();
> + memset(&handle, 0, sizeof(struct swap_map_handle));
> error = get_swap_writer(&handle);
> if (error) {
> pr_err("Cannot get swap writer\n");
> @@ -922,6 +981,9 @@ int swsusp_write(unsigned int flags)
> }
> }
> memset(&snapshot, 0, sizeof(struct snapshot_handle));
> + if (!hibernation_crypto_init(true))
> + /* The image needs to be encrypted or signature. */
> + handle.crypto = true;
> error = snapshot_read_next(&snapshot);
> if (error < PAGE_SIZE) {
> if (error >= 0)
> @@ -1060,6 +1122,8 @@ static int load_image(struct swap_map_handle *handle,
> struct hib_bio_batch hb;
> int err2;
> unsigned nr_pages;
> + unsigned int crypto_page_idx;
> + void *crypt_buf = NULL;
>
> hib_init_batch(&hb);
>
> @@ -1069,18 +1133,46 @@ static int load_image(struct swap_map_handle *handle,
> if (!m)
> m = 1;
> nr_pages = 0;
> + crypto_page_idx = 0;
> + /* Allocate temporary buffer for crypto. */
> + if (handle->crypto) {
> + crypt_buf = (void *)get_zeroed_page(GFP_KERNEL);
> + if (!crypt_buf)
> + return -ENOMEM;
> + }
> start = ktime_get();
> for ( ; ; ) {
> ret = snapshot_write_next(snapshot);
> if (ret <= 0)
> break;
> - ret = swap_read_page(handle, data_of(*snapshot), &hb);
> + if (handle->crypto)
> + ret = swap_read_page(handle, crypt_buf, &hb);
> + else
> + ret = swap_read_page(handle, data_of(*snapshot), &hb);
> if (ret)
> break;
> - if (snapshot->sync_read)
> + /* If encryption is enabled, disable async io. */
> + if (handle->crypto || snapshot->sync_read)
> ret = hib_wait_io(&hb);
> if (ret)
> break;
> + if (handle->crypto) {
> + /*
> + * Need a decryption for the
> + * data read from the block
> + * device.
> + */
> + ret = hibernation_crypto_data(crypt_buf, PAGE_SIZE,
> + data_of(*snapshot),
> + PAGE_SIZE,
> + get_crypto_cmd(false,
> + (crypto_page_idx ==
> + (nr_to_read - 1))),
> + crypto_page_idx);
> + if (ret)
> + break;
> + crypto_page_idx++;
> + }
> if (!(nr_pages % m))
> pr_info("Image loading progress: %3d%%\n",
> nr_pages / m * 10);
> @@ -1097,6 +1189,8 @@ static int load_image(struct swap_map_handle *handle,
> ret = -ENODATA;
> }
> swsusp_show_speed(start, stop, nr_to_read, "Read");
> + if (crypt_buf)
> + free_page((unsigned long)crypt_buf);
> return ret;
> }
>
> @@ -1165,6 +1259,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
> ktime_t start;
> ktime_t stop;
> unsigned nr_pages;
> + unsigned int crypto_page_idx;
> size_t off;
> unsigned i, thr, run_threads, nr_threads;
> unsigned ring = 0, pg = 0, ring_size = 0,
> @@ -1173,6 +1268,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
> unsigned char **page = NULL;
> struct dec_data *data = NULL;
> struct crc_data *crc = NULL;
> + void *first_page = NULL;
>
> hib_init_batch(&hb);
>
> @@ -1278,6 +1374,18 @@ static int load_image_lzo(struct swap_map_handle *handle,
> }
> want = ring_size = i;
>
> + /*
> + * The first page of data[thr] contains the length of
> + * compressed data, this page should not mess up the
> + * read buffer, so we allocate a separate page for it.
> + */
> + if (handle->crypto) {
> + first_page = (void *)get_zeroed_page(GFP_KERNEL);
> + if (!first_page) {
> + ret = -ENOMEM;
> + goto out_clean;
> + }
> + }
> pr_info("Using %u thread(s) for decompression\n", nr_threads);
> pr_info("Loading and decompressing image data (%u pages)...\n",
> nr_to_read);
> @@ -1285,6 +1393,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
> if (!m)
> m = 1;
> nr_pages = 0;
> + crypto_page_idx = 0;
> start = ktime_get();
>
> ret = snapshot_write_next(snapshot);
> @@ -1336,7 +1445,26 @@ static int load_image_lzo(struct swap_map_handle *handle,
> }
>
> for (thr = 0; have && thr < nr_threads; thr++) {
> - data[thr].cmp_len = *(size_t *)page[pg];
> + if (handle->crypto) {
> + /*
> + * Need to decrypt the first page
> + * of each data[thr], which contains
> + * the compressed data length.
> + */
> + ret = hibernation_crypto_data(page[pg],
> + PAGE_SIZE,
> + first_page,
> + PAGE_SIZE,
> + get_crypto_cmd(false,
> + (crypto_page_idx ==
> + (nr_to_read - 1))),
> + crypto_page_idx);
> + if (ret)
> + goto out_finish;
> + data[thr].cmp_len = *(size_t *)first_page;
> + } else {
> + data[thr].cmp_len = *(size_t *)page[pg];
> + }
> if (unlikely(!data[thr].cmp_len ||
> data[thr].cmp_len >
> lzo1x_worst_compress(LZO_UNC_SIZE))) {
> @@ -1358,8 +1486,29 @@ static int load_image_lzo(struct swap_map_handle *handle,
> for (off = 0;
> off < LZO_HEADER + data[thr].cmp_len;
> off += PAGE_SIZE) {
> - memcpy(data[thr].cmp + off,
> - page[pg], PAGE_SIZE);
> + if (handle->crypto) {
> + /*
> + * Decrypt the compressed data
> + * and leverage the decompression
> + * threads to get it done.
> + */
> + ret = hibernation_crypto_data(
> + page[pg],
> + PAGE_SIZE,
> + data[thr].cmp + off,
> + PAGE_SIZE,
> + get_crypto_cmd(false,
> + (crypto_page_idx ==
> + (nr_to_read - 1))),
> + crypto_page_idx);
> + if (ret)
> + goto out_finish;
> + crypto_page_idx++;
> + } else {
> + memcpy(data[thr].cmp + off,
> + page[pg], PAGE_SIZE);
> +
> + }
> have--;
> want++;
> if (++pg >= ring_size)
> @@ -1452,6 +1601,8 @@ static int load_image_lzo(struct swap_map_handle *handle,
> out_clean:
> for (i = 0; i < ring_size; i++)
> free_page((unsigned long)page[i]);
> + if (first_page)
> + free_page((unsigned long)first_page);
> if (crc) {
> if (crc->thr)
> kthread_stop(crc->thr);
> @@ -1482,6 +1633,7 @@ int swsusp_read(unsigned int *flags_p)
> struct swsusp_info *header;
>
> memset(&snapshot, 0, sizeof(struct snapshot_handle));
> + memset(&handle, 0, sizeof(struct swap_map_handle));
> error = snapshot_write_next(&snapshot);
> if (error < PAGE_SIZE)
> return error < 0 ? error : -EFAULT;
> @@ -1489,6 +1641,16 @@ int swsusp_read(unsigned int *flags_p)
> error = get_swap_reader(&handle, flags_p);
> if (error)
> goto end;
> + if (*flags_p & SF_CRYPTO_MODE) {
> + error = hibernation_crypto_init(false);
> + if (!error) {
> + /* The image has been encrypted. */
> + handle.crypto = true;
> + } else {
> + pr_err("Failed to init cipher during resume.\n");
> + goto end;
> + }
> + }
> if (!error)
> error = swap_read_page(&handle, header, NULL);
> if (!error) {
> @@ -1526,6 +1688,10 @@ int swsusp_check(void)
>
> if (!memcmp(HIBERNATE_SIG, swsusp_header->sig, 10)) {
> memcpy(swsusp_header->sig, swsusp_header->orig_sig, 10);
> + /* Read salt passed from previous kernel. */
> + if (swsusp_header->flags & SF_CRYPTO_MODE)
> + hibernation_crypto_restore(
> + (void *)&swsusp_header->salt);
> /* Reset swap signature now */
> error = hib_submit_io(REQ_OP_WRITE, REQ_SYNC,
> swsusp_resume_block,
> --
> 2.7.4
>