ACK: [PATCH 1/1] eCryptfs: Handle failed metadata read in lookup

Brad Figg brad.figg at canonical.com
Thu Mar 1 19:42:52 UTC 2012


On 03/01/2012 11:22 AM, Colin King wrote:
> From: Colin Ian King<colin.king at canonical.com>
>
> When failing to read the lower file's crypto metadata during a lookup,
> eCryptfs must continue on without throwing an error. For example, there
> may be a plaintext file in the lower mount point that the user wants to
> delete through the eCryptfs mount.
>
> If an error is encountered while reading the metadata in lookup(), the
> eCryptfs inode's size could be incorrect. We must be sure to reread the
> plaintext inode size from the metadata when performing an open() or
> setattr(). The metadata is already being read in those paths, so this
> adds minimal performance overhead.
>
> This patch introduces a flag which will track whether or not the
> plaintext inode size has been read so that an incorrect i_size can be
> fixed in the open() or setattr() paths.
>
> BugLink: http://bugs.launchpad.net/bugs/509180
>
> Cc:<stable at kernel.org>
> Signed-off-by: Tyler Hicks<tyhicks at linux.vnet.ibm.com>
>
> (backported from 3aeb86ea4cd15f728147a3bd5469a205ada8c767)
> Signed-off-by: Tim Gardner<tim.gardner at canonical.com>
> Signed-off-by: Colin Ian King<colin.king at canonical.com>
> ---
>   fs/ecryptfs/crypto.c          |   21 +++++++++++++++++++++
>   fs/ecryptfs/ecryptfs_kernel.h |    2 ++
>   fs/ecryptfs/file.c            |    3 ++-
>   fs/ecryptfs/inode.c           |   18 +++---------------
>   4 files changed, 28 insertions(+), 16 deletions(-)
>
> diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
> index 98a2a31..c0fe342 100644
> --- a/fs/ecryptfs/crypto.c
> +++ b/fs/ecryptfs/crypto.c
> @@ -1453,6 +1453,25 @@ static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
>   	crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
>   }
>
> +void ecryptfs_i_size_init(const char *page_virt, struct inode *inode)
> +{
> +	struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
> +	struct ecryptfs_crypt_stat *crypt_stat;
> +	u64 file_size;
> +
> +	crypt_stat =&ecryptfs_inode_to_private(inode)->crypt_stat;
> +	mount_crypt_stat =
> +		&ecryptfs_superblock_to_private(inode->i_sb)->mount_crypt_stat;
> +	if (mount_crypt_stat->flags&  ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
> +		file_size = i_size_read(ecryptfs_inode_to_lower(inode));
> +		if (crypt_stat->flags&  ECRYPTFS_METADATA_IN_XATTR)
> +			file_size += crypt_stat->metadata_size;
> +	} else
> +		file_size = get_unaligned_be64(page_virt);
> +	i_size_write(inode, (loff_t)file_size);
> +	crypt_stat->flags |= ECRYPTFS_I_SIZE_INITIALIZED;
> +}
> +
>   /**
>    * ecryptfs_read_headers_virt
>    * @page_virt: The virtual address into which to read the headers
> @@ -1483,6 +1502,8 @@ static int ecryptfs_read_headers_virt(char *page_virt,
>   		rc = -EINVAL;
>   		goto out;
>   	}
> +	if (!(crypt_stat->flags&  ECRYPTFS_I_SIZE_INITIALIZED))
> +		ecryptfs_i_size_init(page_virt, ecryptfs_dentry->d_inode);
>   	offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
>   	rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
>   				&bytes_read);
> diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
> index 427478e..507500f 100644
> --- a/fs/ecryptfs/ecryptfs_kernel.h
> +++ b/fs/ecryptfs/ecryptfs_kernel.h
> @@ -269,6 +269,7 @@ struct ecryptfs_crypt_stat {
>   #define ECRYPTFS_ENCFN_USE_MOUNT_FNEK 0x00000800
>   #define ECRYPTFS_ENCFN_USE_FEK        0x00001000
>   #define ECRYPTFS_UNLINK_SIGS          0x00002000
> +#define ECRYPTFS_I_SIZE_INITIALIZED   0x00008000
>   	u32 flags;
>   	unsigned int file_version;
>   	size_t iv_bytes;
> @@ -629,6 +630,7 @@ struct ecryptfs_open_req {
>   int ecryptfs_interpose(struct dentry *hidden_dentry,
>   		       struct dentry *this_dentry, struct super_block *sb,
>   		       u32 flags);
> +void ecryptfs_i_size_init(const char *page_virt, struct inode *inode);
>   int ecryptfs_lookup_and_interpose_lower(struct dentry *ecryptfs_dentry,
>   					struct dentry *lower_dentry,
>   					struct inode *ecryptfs_dir_inode);
> diff --git a/fs/ecryptfs/file.c b/fs/ecryptfs/file.c
> index 7d1050e..d30aac2 100644
> --- a/fs/ecryptfs/file.c
> +++ b/fs/ecryptfs/file.c
> @@ -211,7 +211,8 @@ static int ecryptfs_open(struct inode *inode, struct file *file)
>   	if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
>   		ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
>   		mutex_lock(&crypt_stat->cs_mutex);
> -		crypt_stat->flags&= ~(ECRYPTFS_ENCRYPTED);
> +		crypt_stat->flags&= ~(ECRYPTFS_I_SIZE_INITIALIZED
> +					| ECRYPTFS_ENCRYPTED);
>   		mutex_unlock(&crypt_stat->cs_mutex);
>   		rc = 0;
>   		goto out;
> diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
> index f99051b..442947f 100644
> --- a/fs/ecryptfs/inode.c
> +++ b/fs/ecryptfs/inode.c
> @@ -226,10 +226,8 @@ int ecryptfs_lookup_and_interpose_lower(struct dentry *ecryptfs_dentry,
>   	struct dentry *lower_dir_dentry;
>   	struct vfsmount *lower_mnt;
>   	struct inode *lower_inode;
> -	struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
>   	struct ecryptfs_crypt_stat *crypt_stat;
>   	char *page_virt = NULL;
> -	u64 file_size;
>   	int rc = 0;
>
>   	lower_dir_dentry = lower_dentry->d_parent;
> @@ -302,18 +300,7 @@ int ecryptfs_lookup_and_interpose_lower(struct dentry *ecryptfs_dentry,
>   		}
>   		crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
>   	}
> -	mount_crypt_stat =&ecryptfs_superblock_to_private(
> -		ecryptfs_dentry->d_sb)->mount_crypt_stat;
> -	if (mount_crypt_stat->flags&  ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
> -		if (crypt_stat->flags&  ECRYPTFS_METADATA_IN_XATTR)
> -			file_size = (crypt_stat->metadata_size
> -				     + i_size_read(lower_dentry->d_inode));
> -		else
> -			file_size = i_size_read(lower_dentry->d_inode);
> -	} else {
> -		file_size = get_unaligned_be64(page_virt);
> -	}
> -	i_size_write(ecryptfs_dentry->d_inode, (loff_t)file_size);
> +	ecryptfs_i_size_init(page_virt, ecryptfs_dentry->d_inode);
>   out_free_kmem:
>   	kmem_cache_free(ecryptfs_header_cache_2, page_virt);
>   	goto out;
> @@ -927,7 +914,8 @@ static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
>   				goto out;
>   			}
>   			rc = 0;
> -			crypt_stat->flags&= ~(ECRYPTFS_ENCRYPTED);
> +			crypt_stat->flags&= ~(ECRYPTFS_I_SIZE_INITIALIZED
> +						| ECRYPTFS_ENCRYPTED);
>   		}
>   	}
>   	mutex_unlock(&crypt_stat->cs_mutex);


-- 
Brad Figg brad.figg at canonical.com http://www.canonical.com




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