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eCryptfs: Fix metadata in xattr feature regression
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Fixes regression in 8faece5

When using the ecryptfs_xattr_metadata mount option, eCryptfs stores the
metadata (normally stored at the front of the file) in the user.ecryptfs
xattr.  This causes ecryptfs_crypt_stat.num_header_bytes_at_front to be
0, since there is no header data at the front of the file.  This results
in too much memory being requested and ENOMEM being returned from
ecryptfs_write_metadata().

This patch fixes the problem by using the num_header_bytes_at_front
variable for specifying the max size of the metadata, despite whether it
is stored in the header or xattr.

Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>
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Tyler Hicks committed Mar 23, 2010
1 parent 220bf99 commit 157f107
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Showing 4 changed files with 18 additions and 18 deletions.
7 changes: 4 additions & 3 deletions fs/ecryptfs/crypto.c
Original file line number Diff line number Diff line change
Expand Up @@ -381,8 +381,8 @@ static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
static void ecryptfs_lower_offset_for_extent(loff_t *offset, loff_t extent_num,
struct ecryptfs_crypt_stat *crypt_stat)
{
(*offset) = (crypt_stat->num_header_bytes_at_front
+ (crypt_stat->extent_size * extent_num));
(*offset) = ecryptfs_lower_header_size(crypt_stat)
+ (crypt_stat->extent_size * extent_num);
}

/**
Expand Down Expand Up @@ -834,7 +834,8 @@ void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
set_extent_mask_and_shift(crypt_stat);
crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
crypt_stat->num_header_bytes_at_front = 0;
crypt_stat->num_header_bytes_at_front =
ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
else {
if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
crypt_stat->num_header_bytes_at_front =
Expand Down
8 changes: 8 additions & 0 deletions fs/ecryptfs/ecryptfs_kernel.h
Original file line number Diff line number Diff line change
Expand Up @@ -464,6 +464,14 @@ struct ecryptfs_daemon {

extern struct mutex ecryptfs_daemon_hash_mux;

static inline size_t
ecryptfs_lower_header_size(struct ecryptfs_crypt_stat *crypt_stat)
{
if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
return 0;
return crypt_stat->num_header_bytes_at_front;
}

static inline struct ecryptfs_file_info *
ecryptfs_file_to_private(struct file *file)
{
Expand Down
2 changes: 1 addition & 1 deletion fs/ecryptfs/inode.c
Original file line number Diff line number Diff line change
Expand Up @@ -768,7 +768,7 @@ upper_size_to_lower_size(struct ecryptfs_crypt_stat *crypt_stat,
{
loff_t lower_size;

lower_size = crypt_stat->num_header_bytes_at_front;
lower_size = ecryptfs_lower_header_size(crypt_stat);
if (upper_size != 0) {
loff_t num_extents;

Expand Down
19 changes: 5 additions & 14 deletions fs/ecryptfs/mmap.c
Original file line number Diff line number Diff line change
Expand Up @@ -97,19 +97,6 @@ static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
* (big-endian)
* Octet 26: Begin RFC 2440 authentication token packet set
*/
static void set_header_info(char *page_virt,
struct ecryptfs_crypt_stat *crypt_stat)
{
size_t written;
size_t save_num_header_bytes_at_front =
crypt_stat->num_header_bytes_at_front;

crypt_stat->num_header_bytes_at_front =
ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
ecryptfs_write_header_metadata(page_virt + 20, crypt_stat, &written);
crypt_stat->num_header_bytes_at_front =
save_num_header_bytes_at_front;
}

/**
* ecryptfs_copy_up_encrypted_with_header
Expand Down Expand Up @@ -146,9 +133,13 @@ ecryptfs_copy_up_encrypted_with_header(struct page *page,
memset(page_virt, 0, PAGE_CACHE_SIZE);
/* TODO: Support more than one header extent */
if (view_extent_num == 0) {
size_t written;

rc = ecryptfs_read_xattr_region(
page_virt, page->mapping->host);
set_header_info(page_virt, crypt_stat);
ecryptfs_write_header_metadata(page_virt + 20,
crypt_stat,
&written);
}
kunmap_atomic(page_virt, KM_USER0);
flush_dcache_page(page);
Expand Down

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