[RFC PATCH 12/19] btrfs: allow reading normal encrypted extents

From: Mark Harmstone
Date: Tue Jan 08 2019 - 20:28:41 EST

Signed-off-by: Mark Harmstone <mark@xxxxxxxxxxxxx>
---
fs/btrfs/ctree.h | 6 +++
fs/btrfs/encryption.c | 37 +++++++++++++++++
fs/btrfs/encryption.h | 3 ++
fs/btrfs/extent_io.c | 96 ++++++++++++++++++++++++++++++++++++++++---
fs/btrfs/extent_io.h | 2 +
fs/btrfs/extent_map.c | 16 +++++++-
fs/btrfs/extent_map.h | 5 +++
fs/btrfs/file-item.c | 15 ++++++-
fs/btrfs/inode.c | 10 ++++-
fs/btrfs/volumes.h | 2 +
10 files changed, 184 insertions(+), 8 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 51fcc24047f8..4c5b8e8a8580 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2420,6 +2420,12 @@ BTRFS_SETGET_FUNCS(file_extent_encryption, struct btrfs_file_extent_item,
BTRFS_SETGET_FUNCS(file_extent_other_encoding, struct btrfs_file_extent_item,
other_encoding, 16);

+BTRFS_SETGET_FUNCS(file_extent_enc_key_number,
+ struct btrfs_file_extent_item_enc, key_number, 64);
+
+BTRFS_SETGET_FUNCS(file_extent_inline_enc_key_number,
+ struct btrfs_file_extent_inline_enc, key_number, 64);
+
#define BTRFS_ENCRYPTION_KEY_ID_LENGTH 64

struct btrfs_encryption_key_item {
diff --git a/fs/btrfs/encryption.c b/fs/btrfs/encryption.c
index 81313c4378b4..41c001339cc7 100644
--- a/fs/btrfs/encryption.c
+++ b/fs/btrfs/encryption.c
@@ -312,6 +312,43 @@ int btrfs_decrypt(struct btrfs_fs_info *fs_info,
return ret;
}

+int btrfs_decrypt_page(struct btrfs_fs_info *fs_info, struct page *page,
+ u64 key_number, char *iv)
+{
+ struct scatterlist sg;
+ struct skcipher_request *req = NULL;
+ char *kaddr;
+ int ret = -EFAULT;
+ struct btrfs_enc_key *key;
+
+ ret = find_key(fs_info, key_number, &key);
+ if (ret)
+ return ret;
+
+ req = skcipher_request_alloc(key->skcipher, GFP_KERNEL);
+ if (!req) {
+ pr_info("could not allocate skcipher request\n");
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ kaddr = kmap_atomic(page);
+
+ sg_init_one(&sg, kaddr, PAGE_SIZE);
+ skcipher_request_set_crypt(req, &sg, &sg, PAGE_SIZE, iv);
+
+ ret = crypto_skcipher_decrypt(req);
+
+ kunmap_atomic(kaddr);
+
+ if (ret < 0)
+ goto out;
+
+out:
+ if (req)
+ skcipher_request_free(req);
+ return ret;
+}

int btrfs_get_key_id(u64 salt, char *password, unsigned int pwdlen,
char *key_id)
diff --git a/fs/btrfs/encryption.h b/fs/btrfs/encryption.h
index dbc035a880a5..0d24dc51793c 100644
--- a/fs/btrfs/encryption.h
+++ b/fs/btrfs/encryption.h
@@ -33,6 +33,9 @@ struct btrfs_enc_key {
int btrfs_decrypt(struct btrfs_fs_info *fs_info,
unsigned char *data, size_t len);

+int btrfs_decrypt_page(struct btrfs_fs_info *fs_info, struct page *page,
+ u64 key_number, char *iv);
+
int btrfs_get_key_id(u64 salt, char *password, unsigned int pwdlen,
char *key_id);

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index d228f706ff3e..73fb0af50da8 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -23,6 +23,7 @@
#include "rcu-string.h"
#include "backref.h"
#include "disk-io.h"
+#include "encryption.h"

static struct kmem_cache *extent_state_cache;
static struct kmem_cache *extent_buffer_cache;
@@ -2490,6 +2491,26 @@ endio_readpage_release_extent(struct extent_io_tree *tree, u64 start, u64 len,
unlock_extent_cached_atomic(tree, start, end, &cached);
}

+void btrfs_increment_iv(char *iv, u32 inc)
+{
+ u64 i1, ni1, i2;
+
+ if (inc == 0)
+ return;
+
+ i1 = be64_to_cpu(*(u64 *)(iv + sizeof(u64)));
+ ni1 = i1 + inc;
+
+ *(u64 *)(iv + sizeof(u64)) = cpu_to_be64(ni1);
+
+ if (ni1 > i1)
+ return;
+
+ i2 = be64_to_cpu(*(u64 *)iv);
+ i2++;
+ *(u64 *)iv = cpu_to_be64(i2);
+}
+
/*
* after a readpage IO is done, we need to:
* clear the uptodate bits on error
@@ -2606,11 +2627,32 @@ static void end_bio_extent_readpage(struct bio *bio)
pgoff_t end_index = i_size >> PAGE_SHIFT;
unsigned off;

+ if (io_bio->key_number != 0) {
+ char iv[BTRFS_ENCRYPTION_BLOCK_LENGTH];
+
+ memcpy(iv, io_bio->iv,
+ BTRFS_ENCRYPTION_BLOCK_LENGTH);
+ btrfs_increment_iv(iv,
+ i * PAGE_SIZE / BTRFS_ENCRYPTION_BLOCK_LENGTH);
+
+ ret = btrfs_decrypt_page(fs_info, page,
+ io_bio->key_number, iv);
+ } else {
+ ret = 0;
+ }
+
/* Zero out the end if this page straddles i_size */
off = i_size & (PAGE_SIZE-1);
if (page->index == end_index && off)
zero_user_segment(page, off, PAGE_SIZE);
- SetPageUptodate(page);
+
+ if (ret) {
+ uptodate = 0;
+ ClearPageUptodate(page);
+ SetPageError(page);
+ } else {
+ SetPageUptodate(page);
+ }
} else {
ClearPageUptodate(page);
SetPageError(page);
@@ -2752,6 +2794,8 @@ static int __must_check submit_one_bio(struct bio *bio, int mirror_num,
* @mirror_num: desired mirror to read/write
* @prev_bio_flags: flags of previous bio to see if we can merge the current one
* @bio_flags: flags of the current bio to see if we can merge them
+ * @key_number: number of the encryption key (0 if not encrypted)
+ * @iv: encryption initialization vector
*/
static int submit_extent_page(unsigned int opf, struct extent_io_tree *tree,
struct writeback_control *wbc,
@@ -2763,7 +2807,8 @@ static int submit_extent_page(unsigned int opf, struct extent_io_tree *tree,
int mirror_num,
unsigned long prev_bio_flags,
unsigned long bio_flags,
- bool force_bio_submit)
+ bool force_bio_submit, u64 key_number,
+ char *iv)
{
int ret = 0;
struct bio *bio;
@@ -2786,6 +2831,25 @@ static int submit_extent_page(unsigned int opf, struct extent_io_tree *tree,
bio, bio_flags))
can_merge = false;

+ if (prev_bio_flags == bio_flags && contig &&
+ can_merge && !force_bio_submit) {
+ struct btrfs_io_bio *io_bio = btrfs_io_bio(bio);
+
+ if (key_number != io_bio->key_number) {
+ can_merge = false;
+ } else if (key_number != 0) {
+ char iv2[BTRFS_ENCRYPTION_BLOCK_LENGTH];
+
+ memcpy(iv2, io_bio->iv,
+ BTRFS_ENCRYPTION_BLOCK_LENGTH);
+ btrfs_increment_iv(iv2, bio->bi_iter.bi_size /
+ BTRFS_ENCRYPTION_BLOCK_LENGTH);
+
+ can_merge = !memcmp(iv, iv2,
+ BTRFS_ENCRYPTION_BLOCK_LENGTH);
+ }
+ }
+
if (prev_bio_flags != bio_flags || !contig || !can_merge ||
force_bio_submit ||
bio_add_page(bio, page, page_size, pg_offset) < page_size) {
@@ -2813,6 +2877,13 @@ static int submit_extent_page(unsigned int opf, struct extent_io_tree *tree,
wbc_account_io(wbc, page, page_size);
}

+ if (key_number != 0) {
+ struct btrfs_io_bio *io_bio = btrfs_io_bio(bio);
+
+ io_bio->key_number = key_number;
+ memcpy(io_bio->iv, iv, BTRFS_ENCRYPTION_BLOCK_LENGTH);
+ }
+
*bio_ret = bio;

return ret;
@@ -2924,6 +2995,8 @@ static int __do_readpage(struct extent_io_tree *tree,
while (cur <= end) {
bool force_bio_submit = false;
u64 offset;
+ char iv[BTRFS_ENCRYPTION_BLOCK_LENGTH];
+ u64 key_number = 0;

if (cur >= last_byte) {
char *userpage;
@@ -2951,6 +3024,9 @@ static int __do_readpage(struct extent_io_tree *tree,
BUG_ON(extent_map_end(em) <= cur);
BUG_ON(end < cur);

+ if (test_bit(EXTENT_FLAG_ENCRYPTED, &em->flags))
+ this_bio_flag |= EXTENT_BIO_ENCRYPTED;
+
if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
this_bio_flag |= EXTENT_BIO_COMPRESSED;
extent_set_compress_type(&this_bio_flag,
@@ -3014,6 +3090,16 @@ static int __do_readpage(struct extent_io_tree *tree,
if (prev_em_start)
*prev_em_start = em->orig_start;

+ if (this_bio_flag & EXTENT_BIO_ENCRYPTED &&
+ !(this_bio_flag & EXTENT_BIO_COMPRESSED)) {
+ key_number = em->key_number;
+ memcpy(iv, em->iv, BTRFS_ENCRYPTION_BLOCK_LENGTH);
+
+ if (extent_offset != 0)
+ btrfs_increment_iv(iv,
+ extent_offset / BTRFS_ENCRYPTION_BLOCK_LENGTH);
+ }
+
free_extent_map(em);
em = NULL;

@@ -3061,7 +3147,7 @@ static int __do_readpage(struct extent_io_tree *tree,
end_bio_extent_readpage, mirror_num,
*bio_flags,
this_bio_flag,
- force_bio_submit);
+ force_bio_submit, key_number, iv);
if (!ret) {
nr++;
*bio_flags = this_bio_flag;
@@ -3425,7 +3511,7 @@ static noinline_for_stack int __extent_writepage_io(struct inode *inode,
page, offset, iosize, pg_offset,
bdev, &epd->bio,
end_bio_extent_writepage,
- 0, 0, 0, false);
+ 0, 0, 0, false, 0, NULL);
if (ret) {
SetPageError(page);
if (PageWriteback(page))
@@ -3738,7 +3824,7 @@ static noinline_for_stack int write_one_eb(struct extent_buffer *eb,
p, offset, PAGE_SIZE, 0, bdev,
&epd->bio,
end_bio_extent_buffer_writepage,
- 0, 0, 0, false);
+ 0, 0, 0, false, 0, NULL);
if (ret) {
set_btree_ioerr(p);
if (PageWriteback(p))
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 369daa5d4f73..54a7d6864d05 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -35,6 +35,7 @@
* type for this bio
*/
#define EXTENT_BIO_COMPRESSED 1
+#define EXTENT_BIO_ENCRYPTED 2
#define EXTENT_BIO_FLAG_SHIFT 16

/* these are bit numbers for test/set bit */
@@ -553,5 +554,6 @@ u64 btrfs_find_lock_delalloc_range(struct inode *inode,
#endif
struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info,
u64 start);
+void btrfs_increment_iv(char *iv, u32 inc);

#endif
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 7eea8b6e2cd3..0cc0ffbe0453 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -6,7 +6,7 @@
#include "ctree.h"
#include "extent_map.h"
#include "compression.h"
-
+#include "extent_io.h"

static struct kmem_cache *extent_map_cache;

@@ -210,6 +210,20 @@ static int mergable_maps(struct extent_map *prev, struct extent_map *next)
if (!list_empty(&prev->list) || !list_empty(&next->list))
return 0;

+ if (prev->key_number != next->key_number)
+ return 0;
+
+ if (next->key_number != 0) {
+ char iv[BTRFS_ENCRYPTION_BLOCK_LENGTH];
+
+ memcpy(iv, prev->iv, BTRFS_ENCRYPTION_BLOCK_LENGTH);
+ btrfs_increment_iv(iv, prev->len /
+ BTRFS_ENCRYPTION_BLOCK_LENGTH);
+
+ if (memcmp(iv, next->iv, BTRFS_ENCRYPTION_BLOCK_LENGTH))
+ return 0;
+ }
+
if (extent_map_end(prev) == next->start &&
prev->flags == next->flags &&
prev->bdev == next->bdev &&
diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index 31977ffd6190..2bc1087564a1 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -5,6 +5,7 @@

#include <linux/rbtree.h>
#include <linux/refcount.h>
+#include <linux/btrfs_tree.h>

#define EXTENT_MAP_LAST_BYTE ((u64)-4)
#define EXTENT_MAP_HOLE ((u64)-3)
@@ -14,6 +15,7 @@
/* bits for the flags field */
#define EXTENT_FLAG_PINNED 0 /* this entry not yet on disk, don't free it */
#define EXTENT_FLAG_COMPRESSED 1
+#define EXTENT_FLAG_ENCRYPTED 2
#define EXTENT_FLAG_PREALLOC 3 /* pre-allocated extent */
#define EXTENT_FLAG_LOGGING 4 /* Logging this extent */
#define EXTENT_FLAG_FILLING 5 /* Filling in a preallocated extent */
@@ -45,6 +47,9 @@ struct extent_map {
};
refcount_t refs;
unsigned int compress_type;
+ unsigned int encrypt_type;
+ u64 key_number;
+ char iv[BTRFS_ENCRYPTION_BLOCK_LENGTH];
struct list_head list;
};

diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index ba74827beb32..a903997e67ba 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -13,6 +13,7 @@
#include "volumes.h"
#include "print-tree.h"
#include "compression.h"
+#include "encryption.h"

#define __MAX_CSUM_ITEMS(r, size) ((unsigned long)(((BTRFS_LEAF_DATA_SIZE(r) - \
sizeof(struct btrfs_item) * 2) / \
@@ -931,6 +932,7 @@ void btrfs_extent_item_to_extent_map(struct btrfs_inode *inode,
u64 bytenr;
u8 type = btrfs_file_extent_type(leaf, fi);
int compress_type = btrfs_file_extent_compression(leaf, fi);
+ int encrypt_type = btrfs_file_extent_encryption(leaf, fi);

em->bdev = fs_info->fs_devices->latest_bdev;
btrfs_item_key_to_cpu(leaf, &key, slot);
@@ -960,7 +962,18 @@ void btrfs_extent_item_to_extent_map(struct btrfs_inode *inode,
em->block_start = EXTENT_MAP_HOLE;
return;
}
- if (compress_type != BTRFS_COMPRESS_NONE) {
+
+ if (encrypt_type != BTRFS_ENCRYPTION_NONE) {
+ set_bit(EXTENT_FLAG_ENCRYPTED, &em->flags);
+ em->encrypt_type = encrypt_type;
+ em->block_start = bytenr;
+ em->block_len = em->orig_block_len;
+
+ if (compress_type != BTRFS_COMPRESS_NONE) {
+ set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
+ em->compress_type = compress_type;
+ }
+ } else if (compress_type != BTRFS_COMPRESS_NONE) {
set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
em->compress_type = compress_type;
em->block_start = bytenr;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 7018a2169e3e..52ea7d7c880b 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1953,7 +1953,7 @@ int btrfs_merge_bio_hook(struct page *page, unsigned long offset,
u64 map_length;
int ret;

- if (bio_flags & EXTENT_BIO_COMPRESSED)
+ if (bio_flags & (EXTENT_BIO_COMPRESSED | EXTENT_BIO_ENCRYPTED))
return 0;

length = bio->bi_iter.bi_size;
@@ -7039,6 +7039,14 @@ struct extent_map *btrfs_get_extent(struct btrfs_inode *inode,
btrfs_extent_item_to_extent_map(inode, path, item,
new_inline, em);

+ if (btrfs_file_extent_type(leaf, item) != BTRFS_ENCRYPTION_NONE) {
+ em->key_number = btrfs_file_extent_enc_key_number(leaf,
+ (struct btrfs_file_extent_item_enc *)item);
+
+ read_eb_member(leaf, item, struct btrfs_file_extent_item_enc,
+ iv, em->iv);
+ }
+
if (found_type == BTRFS_FILE_EXTENT_REG ||
found_type == BTRFS_FILE_EXTENT_PREALLOC) {
goto insert;
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index aefce895e994..fc12c28bdd93 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -271,6 +271,8 @@ struct btrfs_io_bio {
u8 *csum_allocated;
btrfs_io_bio_end_io_t *end_io;
struct bvec_iter iter;
+ u64 key_number;
+ char iv[BTRFS_ENCRYPTION_BLOCK_LENGTH];
/*
* This member must come last, bio_alloc_bioset will allocate enough
* bytes for entire btrfs_io_bio but relies on bio being last.
--
2.19.2