Re: [PATCH 2/3][RFC] PM / Hibernate: Encrypt the snapshot pages before submitted to the block device

joeyli
2018-06-28T13:07:48Z

Hi Chen Yu,

On Wed, Jun 20, 2018 at 05:40:32PM +0800, Chen Yu wrote:
> Use the helper functions introduced previously 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.
>

I want to suggest my solution that it direct signs/encrypts the
memory snapshot image. This solution is already shipped with
SLE12 a couple of years:

https://github.com/joeyli/linux-s4sign/commits/s4sign-hmac-encrypted-key-v0.2-v4.17-rc3

The above patches still need to clean up. I am working on some
other bugs, but I can clean up and send out it ASAP.

The advantage of this solution is that it produces a signed and
encrypted image. Not just for writing to block device by kernel,
it also can provide a signed/encrypted image to user space. User
space can store the encrypted image to anywhere.

I am OK for your user space key generator because I didn't have
similar solution yet. I am working on the EFI master key and also
want to adapt hibernation to keyring. I will continue the works.

Thanks a lot!
Joey Lee

> 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: Borislav Petkov <bp@alien8.de>
> Cc: "Lee, Chun-Yi" <jlee@suse.com>
> Cc: linux-pm@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Chen Yu <yu.c.chen@intel.com>
> ---
> kernel/power/power.h | 1 +
> kernel/power/swap.c | 215 ++++++++++++++++++++++++++++++++++++++++++++++++---
> 2 files changed, 205 insertions(+), 11 deletions(-)
>
> diff --git a/kernel/power/power.h b/kernel/power/power.h
> index 660aac3..637695c 100644
> --- a/kernel/power/power.h
> +++ b/kernel/power/power.h
> @@ -207,6 +207,7 @@ extern int swsusp_swap_in_use(void);
> #define SF_PLATFORM_MODE 1
> #define SF_NOCOMPRESS_MODE 2
> #define SF_CRC32_MODE 4
> +#define SF_ENCRYPT_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..2b6b3d0 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_SALT_BYTES];
> u32 crc32;
> sector_t image;
> unsigned int flags; /* Flags to pass to the "boot" kernel */
> + char salt[HIBERNATE_SALT_BYTES];
> char orig_sig[10];
> char sig[10];
> } __packed;
> @@ -127,6 +129,53 @@ struct swsusp_extent {
> unsigned long end;
> };
>
> +/* For encryption/decryption. */
> +static struct hibernation_crypto *hibernation_crypto_ops;
> +
> +void set_hibernation_ops(struct hibernation_crypto *ops)
> +{
> + hibernation_crypto_ops = ops;
> +}
> +EXPORT_SYMBOL_GPL(set_hibernation_ops);
> +
> +static int crypto_data(const char *inbuf,
> + int inlen,
> + char *outbuf,
> + int outlen,
> + bool encrypt,
> + int page_idx)
> +{
> + if (hibernation_crypto_ops &&
> + hibernation_crypto_ops->crypto_data)
> + return hibernation_crypto_ops->crypto_data(inbuf,
> + inlen, outbuf, outlen, encrypt, page_idx);
> + else
> + return -EINVAL;
> +}
> +
> +static void crypto_save(void *outbuf)
> +{
> + if (hibernation_crypto_ops &&
> + hibernation_crypto_ops->save)
> + hibernation_crypto_ops->save(outbuf);
> +}
> +
> +static void crypto_restore(void *inbuf)
> +{
> + if (hibernation_crypto_ops &&
> + hibernation_crypto_ops->restore)
> + hibernation_crypto_ops->restore(inbuf);
> +}
> +
> +static int crypto_init(bool suspend)
> +{
> + if (hibernation_crypto_ops &&
> + hibernation_crypto_ops->init)
> + return hibernation_crypto_ops->init(suspend);
> + else
> + return -EINVAL;
> +}
> +
> static struct rb_root swsusp_extents = RB_ROOT;
>
> static int swsusp_extents_insert(unsigned long swap_offset)
> @@ -318,6 +367,10 @@ 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_ENCRYPT_MODE;
> + crypto_save((void *)swsusp_header->salt);
> + }
> error = hib_submit_io(REQ_OP_WRITE, REQ_SYNC,
> swsusp_resume_block, swsusp_header, NULL);
> } else {
> @@ -535,11 +588,12 @@ static int save_image(struct swap_map_handle *handle,
> {
> unsigned int m;
> int ret;
> - int nr_pages;
> + int nr_pages, 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 +603,33 @@ static int save_image(struct swap_map_handle *handle,
> if (!m)
> m = 1;
> nr_pages = 0;
> + crypto_page_idx = 0;
> + 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 = crypto_data(data_of(*snapshot),
> + PAGE_SIZE,
> + crypt_buf,
> + PAGE_SIZE,
> + true,
> + 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 +644,9 @@ 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;
> }
>
> @@ -671,7 +749,7 @@ static int save_image_lzo(struct swap_map_handle *handle,
> {
> unsigned int m;
> int ret = 0;
> - int nr_pages;
> + int nr_pages, crypto_page_idx;
> int err2;
> struct hib_bio_batch hb;
> ktime_t start;
> @@ -767,6 +845,7 @@ 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 +914,25 @@ 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 = crypto_data(data[thr].cmp + off,
> + PAGE_SIZE,
> + page,
> + PAGE_SIZE,
> + true,
> + 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 +1006,7 @@ 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 +1020,9 @@ int swsusp_write(unsigned int flags)
> }
> }
> memset(&snapshot, 0, sizeof(struct snapshot_handle));
> + if (!crypto_init(true))
> + /* The image needs to be encrypted. */
> + handle.crypto = true;
> error = snapshot_read_next(&snapshot);
> if (error < PAGE_SIZE) {
> if (error >= 0)
> @@ -1059,7 +1160,8 @@ static int load_image(struct swap_map_handle *handle,
> ktime_t stop;
> struct hib_bio_batch hb;
> int err2;
> - unsigned nr_pages;
> + unsigned nr_pages, crypto_page_idx;
> + void *crypt_buf = NULL;
>
> hib_init_batch(&hb);
>
> @@ -1069,18 +1171,42 @@ static int load_image(struct swap_map_handle *handle,
> if (!m)
> m = 1;
> nr_pages = 0;
> + crypto_page_idx = 0;
> + 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)
> ret = hib_wait_io(&hb);
> if (ret)
> break;
> + if (handle->crypto) {
> + /*
> + * Need a decryption for the
> + * data read from the block
> + * device.
> + */
> + ret = crypto_data(crypt_buf, PAGE_SIZE,
> + data_of(*snapshot),
> + PAGE_SIZE,
> + false,
> + 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 +1223,8 @@ 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;
> }
>
> @@ -1164,7 +1292,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
> struct hib_bio_batch hb;
> ktime_t start;
> ktime_t stop;
> - unsigned nr_pages;
> + unsigned nr_pages, crypto_page_idx;
> size_t off;
> unsigned i, thr, run_threads, nr_threads;
> unsigned ring = 0, pg = 0, ring_size = 0,
> @@ -1173,6 +1301,7 @@ 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 +1407,18 @@ 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 +1426,7 @@ 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 +1478,24 @@ 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 = crypto_data(page[pg],
> + PAGE_SIZE,
> + first_page,
> + PAGE_SIZE,
> + false,
> + 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 +1517,26 @@ 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 = crypto_data(page[pg],
> + PAGE_SIZE,
> + data[thr].cmp + off,
> + PAGE_SIZE,
> + false,
> + 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 +1629,8 @@ 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 +1661,7 @@ 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 +1669,16 @@ int swsusp_read(unsigned int *flags_p)
> error = get_swap_reader(&handle, flags_p);
> if (error)
> goto end;
> + if (*flags_p & SF_ENCRYPT_MODE) {
> + error = 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 +1716,9 @@ 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_ENCRYPT_MODE)
> + 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
>