Commit 778aeb42 authored by Tyler Hicks's avatar Tyler Hicks
Browse files

eCryptfs: Cleanup and optimize ecryptfs_lookup_interpose() 



ecryptfs_lookup_interpose() has turned into spaghetti code over the
years. This is an effort to clean it up.

 - Shorten overly descriptive variable names such as ecryptfs_dentry
 - Simplify gotos and error paths
 - Create helper function for reading plaintext i_size from metadata

It also includes an optimization when reading i_size from the metadata.
A complete page-sized kmem_cache_alloc() was being done to read in 16
bytes of metadata. The buffer for that is now statically declared.

Signed-off-by: default avatarTyler Hicks <tyhicks@linux.vnet.ibm.com>
parent 7a86617e

fs/ecryptfs/crypto.c

+21 −24
Original line number Diff line number Diff line
@@ -1201,24 +1201,19 @@ int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code) 
	return rc;

}



int ecryptfs_read_and_validate_header_region(char *data,

					     struct inode *ecryptfs_inode)

int ecryptfs_read_and_validate_header_region(struct inode *inode)

{

	struct ecryptfs_crypt_stat *crypt_stat =

		&(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);

	u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];

	u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;

	int rc;



	if (crypt_stat->extent_size == 0)

		crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;

	rc = ecryptfs_read_lower(data, 0, crypt_stat->extent_size,

				 ecryptfs_inode);

	if (rc < 0) {

		printk(KERN_ERR "%s: Error reading header region; rc = [%d]\n",

		       __func__, rc);

		goto out;

	}

	rc = ecryptfs_validate_marker(data + ECRYPTFS_FILE_SIZE_BYTES);

out:

	rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,

				 inode);

	if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)

		return rc >= 0 ? -EINVAL : rc;

	rc = ecryptfs_validate_marker(marker);

	if (!rc)

		ecryptfs_i_size_init(file_size, inode);

	return rc;

}
@@ -1562,19 +1557,21 @@ out: 
	return rc;

}



int ecryptfs_read_and_validate_xattr_region(char *page_virt,

int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,

					    struct inode *inode)

{

	u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];

	u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;

	int rc;



	rc = ecryptfs_read_xattr_region(page_virt, inode);

	if (rc)

		goto out;

	rc = ecryptfs_validate_marker(page_virt + ECRYPTFS_FILE_SIZE_BYTES);

	if (rc)

		printk(KERN_WARNING "Valid data found in [%s] xattr, but "

			"the marker is invalid\n", ECRYPTFS_XATTR_NAME);

out:

	rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),

				     ECRYPTFS_XATTR_NAME, file_size,

				     ECRYPTFS_SIZE_AND_MARKER_BYTES);

	if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)

		return rc >= 0 ? -EINVAL : rc;

	rc = ecryptfs_validate_marker(marker);

	if (!rc)

		ecryptfs_i_size_init(file_size, inode);

	return rc;

}

fs/ecryptfs/ecryptfs_kernel.h

+4 −3
Original line number Diff line number Diff line
@@ -200,6 +200,8 @@ ecryptfs_get_key_payload_data(struct key *key) 
#define MAGIC_ECRYPTFS_MARKER 0x3c81b7f5

#define MAGIC_ECRYPTFS_MARKER_SIZE_BYTES 8	/* 4*2 */

#define ECRYPTFS_FILE_SIZE_BYTES (sizeof(u64))

#define ECRYPTFS_SIZE_AND_MARKER_BYTES (ECRYPTFS_FILE_SIZE_BYTES \

					+ MAGIC_ECRYPTFS_MARKER_SIZE_BYTES)

#define ECRYPTFS_DEFAULT_CIPHER "aes"

#define ECRYPTFS_DEFAULT_KEY_BYTES 16

#define ECRYPTFS_DEFAULT_HASH "md5"
@@ -659,9 +661,8 @@ int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry); 
void ecryptfs_write_crypt_stat_flags(char *page_virt,

				     struct ecryptfs_crypt_stat *crypt_stat,

				     size_t *written);

int ecryptfs_read_and_validate_header_region(char *data,

					     struct inode *ecryptfs_inode);

int ecryptfs_read_and_validate_xattr_region(char *page_virt,

int ecryptfs_read_and_validate_header_region(struct inode *inode);

int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,

					    struct inode *inode);

u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes);

int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code);

fs/ecryptfs/inode.c

+63 −78
Original line number Diff line number Diff line
@@ -307,105 +307,90 @@ out: 
	return rc;

}



static int ecryptfs_i_size_read(struct dentry *dentry, struct inode *inode)

{

	struct ecryptfs_crypt_stat *crypt_stat;

	int rc;



	rc = ecryptfs_get_lower_file(dentry, inode);

	if (rc) {

		printk(KERN_ERR "%s: Error attempting to initialize "

			"the lower file for the dentry with name "

			"[%s]; rc = [%d]\n", __func__,

			dentry->d_name.name, rc);

		return rc;

	}



	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;

	/* TODO: lock for crypt_stat comparison */

	if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED))

		ecryptfs_set_default_sizes(crypt_stat);



	rc = ecryptfs_read_and_validate_header_region(inode);

	ecryptfs_put_lower_file(inode);

	if (rc) {

		rc = ecryptfs_read_and_validate_xattr_region(dentry, inode);

		if (!rc)

			crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;

	}



	/* Must return 0 to allow non-eCryptfs files to be looked up, too */

	return 0;

}



/**

 * ecryptfs_lookup_interpose - Dentry interposition for a lookup

 */

static int ecryptfs_lookup_interpose(struct dentry *ecryptfs_dentry,

static int ecryptfs_lookup_interpose(struct dentry *dentry,

				     struct dentry *lower_dentry,

				     struct inode *ecryptfs_dir_inode)

				     struct inode *dir_inode)

{

	struct dentry *lower_dir_dentry;

	struct inode *inode, *lower_inode = lower_dentry->d_inode;

	struct ecryptfs_dentry_info *dentry_info;

	struct vfsmount *lower_mnt;

	struct inode *inode, *lower_inode;

	struct ecryptfs_crypt_stat *crypt_stat;

	char *page_virt = NULL;

	int put_lower = 0, rc = 0;



	lower_dir_dentry = lower_dentry->d_parent;

	lower_mnt = mntget(ecryptfs_dentry_to_lower_mnt(

				   ecryptfs_dentry->d_parent));

	lower_inode = lower_dentry->d_inode;

	fsstack_copy_attr_atime(ecryptfs_dir_inode, lower_dir_dentry->d_inode);

	int rc = 0;



	lower_mnt = mntget(ecryptfs_dentry_to_lower_mnt(dentry->d_parent));

	fsstack_copy_attr_atime(dir_inode, lower_dentry->d_parent->d_inode);

	BUG_ON(!lower_dentry->d_count);

	ecryptfs_set_dentry_private(ecryptfs_dentry,

				    kmem_cache_alloc(ecryptfs_dentry_info_cache,

						     GFP_KERNEL));

	if (!ecryptfs_dentry_to_private(ecryptfs_dentry)) {

		rc = -ENOMEM;



	dentry_info = kmem_cache_alloc(ecryptfs_dentry_info_cache, GFP_KERNEL);

	ecryptfs_set_dentry_private(dentry, dentry_info);

	if (!dentry_info) {

		printk(KERN_ERR "%s: Out of memory whilst attempting "

		       "to allocate ecryptfs_dentry_info struct\n",

			__func__);

		goto out_put;

		dput(lower_dentry);

		mntput(lower_mnt);

		d_drop(dentry);

		return -ENOMEM;

	}

	ecryptfs_set_dentry_lower(ecryptfs_dentry, lower_dentry);

	ecryptfs_set_dentry_lower_mnt(ecryptfs_dentry, lower_mnt);

	ecryptfs_set_dentry_lower(dentry, lower_dentry);

	ecryptfs_set_dentry_lower_mnt(dentry, lower_mnt);



	if (!lower_dentry->d_inode) {

		/* We want to add because we couldn't find in lower */

		d_add(ecryptfs_dentry, NULL);

		goto out;

		d_add(dentry, NULL);

		return 0;

	}

	inode = __ecryptfs_get_inode(lower_inode, ecryptfs_dir_inode->i_sb);

	inode = __ecryptfs_get_inode(lower_inode, dir_inode->i_sb);

	if (IS_ERR(inode)) {

		rc = PTR_ERR(inode);

		printk(KERN_ERR "%s: Error interposing; rc = [%d]\n",

		       __func__, rc);

		goto out;

	}

	if (!S_ISREG(inode->i_mode)) {

		if (inode->i_state & I_NEW)

			unlock_new_inode(inode);

		d_add(ecryptfs_dentry, inode);

		goto out;

	}

	/* Released in this function */

	page_virt = kmem_cache_zalloc(ecryptfs_header_cache_2, GFP_USER);

	if (!page_virt) {

		printk(KERN_ERR "%s: Cannot kmem_cache_zalloc() a page\n",

		       __func__);

		rc = -ENOMEM;

		make_bad_inode(inode);

		goto out;

		printk(KERN_ERR "%s: Error interposing; rc = [%ld]\n",

		       __func__, PTR_ERR(inode));

		return PTR_ERR(inode);

	}

	rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);

	if (S_ISREG(inode->i_mode)) {

		rc = ecryptfs_i_size_read(dentry, inode);

		if (rc) {

		printk(KERN_ERR "%s: Error attempting to initialize "

			"the lower file for the dentry with name "

			"[%s]; rc = [%d]\n", __func__,

			ecryptfs_dentry->d_name.name, rc);

			make_bad_inode(inode);

		goto out_free_kmem;

	}

	put_lower = 1;

	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;

	/* TODO: lock for crypt_stat comparison */

	if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED))

			ecryptfs_set_default_sizes(crypt_stat);

	rc = ecryptfs_read_and_validate_header_region(page_virt, inode);

	if (rc) {

		memset(page_virt, 0, PAGE_CACHE_SIZE);

		rc = ecryptfs_read_and_validate_xattr_region(page_virt,

							     inode);

		if (rc) {

			rc = 0;

			goto unlock_inode;

			return rc;

		}

		crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;

	}

	ecryptfs_i_size_init(page_virt, inode);

unlock_inode:



	if (inode->i_state & I_NEW)

		unlock_new_inode(inode);

	d_add(ecryptfs_dentry, inode);

out_free_kmem:

	kmem_cache_free(ecryptfs_header_cache_2, page_virt);

	goto out;

out_put:

	dput(lower_dentry);

	mntput(lower_mnt);

	d_drop(ecryptfs_dentry);

out:

	if (put_lower)

		ecryptfs_put_lower_file(inode);

	d_add(dentry, inode);



	return rc;

}

CRA Git | Maintained and supported by SUSTech CRA and CCSE