Commit 3aeb86ea authored by Tyler Hicks's avatar Tyler Hicks
Browse files

eCryptfs: Handle failed metadata read in lookup 

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.

https://bugs.launchpad.net/bugs/509180



Cc: <stable@kernel.org>
Signed-off-by: default avatarTyler Hicks <tyhicks@linux.vnet.ibm.com>
parent 332ab16f

fs/ecryptfs/crypto.c

+21 −0
Original line number Diff line number Diff line
@@ -1452,6 +1452,25 @@ 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
@@ -1482,6 +1501,8 @@ 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);

fs/ecryptfs/ecryptfs_kernel.h

+2 −0
Original line number Diff line number Diff line
@@ -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   0x00004000

	u32 flags;

	unsigned int file_version;

	size_t iv_bytes;
@@ -628,6 +629,7 @@ 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);

fs/ecryptfs/file.c

+2 −1
Original line number Diff line number Diff line
@@ -235,7 +235,8 @@ static int ecryptfs_open(struct inode *inode, struct file *file) 
				goto out_put;

			}

			rc = 0;

			crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);

			crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED

					       | ECRYPTFS_ENCRYPTED);

			mutex_unlock(&crypt_stat->cs_mutex);

			goto out;

		}

fs/ecryptfs/inode.c

+3 −15
Original line number Diff line number Diff line
@@ -225,10 +225,8 @@ 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 put_lower = 0, 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;
@@ -937,7 +924,8 @@ 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);

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