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: Tyler Hicks <tyhicks@linux.vnet.ibm.com>
This commit is contained in:
Tyler Hicks
parent
7a86617e55
commit
778aeb42a7
@ -1201,24 +1201,19 @@ int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
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return rc;
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}
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int ecryptfs_read_and_validate_header_region(char *data,
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struct inode *ecryptfs_inode)
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int ecryptfs_read_and_validate_header_region(struct inode *inode)
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{
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struct ecryptfs_crypt_stat *crypt_stat =
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&(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
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u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
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u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
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int rc;
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if (crypt_stat->extent_size == 0)
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crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
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rc = ecryptfs_read_lower(data, 0, crypt_stat->extent_size,
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ecryptfs_inode);
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if (rc < 0) {
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printk(KERN_ERR "%s: Error reading header region; rc = [%d]\n",
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__func__, rc);
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goto out;
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}
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rc = ecryptfs_validate_marker(data + ECRYPTFS_FILE_SIZE_BYTES);
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out:
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rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
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inode);
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if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
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return rc >= 0 ? -EINVAL : rc;
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rc = ecryptfs_validate_marker(marker);
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if (!rc)
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ecryptfs_i_size_init(file_size, inode);
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return rc;
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}
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@ -1562,19 +1557,21 @@ out:
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return rc;
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}
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int ecryptfs_read_and_validate_xattr_region(char *page_virt,
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int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
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struct inode *inode)
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{
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u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
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u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
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int rc;
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rc = ecryptfs_read_xattr_region(page_virt, inode);
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if (rc)
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goto out;
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rc = ecryptfs_validate_marker(page_virt + ECRYPTFS_FILE_SIZE_BYTES);
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if (rc)
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printk(KERN_WARNING "Valid data found in [%s] xattr, but "
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"the marker is invalid\n", ECRYPTFS_XATTR_NAME);
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out:
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rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
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ECRYPTFS_XATTR_NAME, file_size,
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ECRYPTFS_SIZE_AND_MARKER_BYTES);
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if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
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return rc >= 0 ? -EINVAL : rc;
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rc = ecryptfs_validate_marker(marker);
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if (!rc)
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ecryptfs_i_size_init(file_size, inode);
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return rc;
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}
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@ -200,6 +200,8 @@ ecryptfs_get_key_payload_data(struct key *key)
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#define MAGIC_ECRYPTFS_MARKER 0x3c81b7f5
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#define MAGIC_ECRYPTFS_MARKER_SIZE_BYTES 8 /* 4*2 */
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#define ECRYPTFS_FILE_SIZE_BYTES (sizeof(u64))
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#define ECRYPTFS_SIZE_AND_MARKER_BYTES (ECRYPTFS_FILE_SIZE_BYTES \
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+ MAGIC_ECRYPTFS_MARKER_SIZE_BYTES)
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#define ECRYPTFS_DEFAULT_CIPHER "aes"
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#define ECRYPTFS_DEFAULT_KEY_BYTES 16
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#define ECRYPTFS_DEFAULT_HASH "md5"
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@ -659,9 +661,8 @@ int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry);
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void ecryptfs_write_crypt_stat_flags(char *page_virt,
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struct ecryptfs_crypt_stat *crypt_stat,
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size_t *written);
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int ecryptfs_read_and_validate_header_region(char *data,
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struct inode *ecryptfs_inode);
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int ecryptfs_read_and_validate_xattr_region(char *page_virt,
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int ecryptfs_read_and_validate_header_region(struct inode *inode);
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int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
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struct inode *inode);
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u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes);
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int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code);
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@ -307,105 +307,90 @@ out:
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return rc;
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}
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/**
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* ecryptfs_lookup_interpose - Dentry interposition for a lookup
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*/
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static int ecryptfs_lookup_interpose(struct dentry *ecryptfs_dentry,
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struct dentry *lower_dentry,
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struct inode *ecryptfs_dir_inode)
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static int ecryptfs_i_size_read(struct dentry *dentry, struct inode *inode)
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{
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struct dentry *lower_dir_dentry;
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struct vfsmount *lower_mnt;
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struct inode *inode, *lower_inode;
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struct ecryptfs_crypt_stat *crypt_stat;
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char *page_virt = NULL;
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int put_lower = 0, rc = 0;
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int rc;
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lower_dir_dentry = lower_dentry->d_parent;
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lower_mnt = mntget(ecryptfs_dentry_to_lower_mnt(
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ecryptfs_dentry->d_parent));
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lower_inode = lower_dentry->d_inode;
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fsstack_copy_attr_atime(ecryptfs_dir_inode, lower_dir_dentry->d_inode);
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BUG_ON(!lower_dentry->d_count);
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ecryptfs_set_dentry_private(ecryptfs_dentry,
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kmem_cache_alloc(ecryptfs_dentry_info_cache,
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GFP_KERNEL));
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if (!ecryptfs_dentry_to_private(ecryptfs_dentry)) {
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rc = -ENOMEM;
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printk(KERN_ERR "%s: Out of memory whilst attempting "
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"to allocate ecryptfs_dentry_info struct\n",
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__func__);
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goto out_put;
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}
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ecryptfs_set_dentry_lower(ecryptfs_dentry, lower_dentry);
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ecryptfs_set_dentry_lower_mnt(ecryptfs_dentry, lower_mnt);
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if (!lower_dentry->d_inode) {
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/* We want to add because we couldn't find in lower */
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d_add(ecryptfs_dentry, NULL);
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goto out;
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}
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inode = __ecryptfs_get_inode(lower_inode, ecryptfs_dir_inode->i_sb);
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if (IS_ERR(inode)) {
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rc = PTR_ERR(inode);
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printk(KERN_ERR "%s: Error interposing; rc = [%d]\n",
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__func__, rc);
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goto out;
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}
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if (!S_ISREG(inode->i_mode)) {
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if (inode->i_state & I_NEW)
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unlock_new_inode(inode);
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d_add(ecryptfs_dentry, inode);
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goto out;
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}
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/* Released in this function */
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page_virt = kmem_cache_zalloc(ecryptfs_header_cache_2, GFP_USER);
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if (!page_virt) {
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printk(KERN_ERR "%s: Cannot kmem_cache_zalloc() a page\n",
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__func__);
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rc = -ENOMEM;
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make_bad_inode(inode);
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goto out;
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}
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rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
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rc = ecryptfs_get_lower_file(dentry, inode);
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if (rc) {
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printk(KERN_ERR "%s: Error attempting to initialize "
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"the lower file for the dentry with name "
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"[%s]; rc = [%d]\n", __func__,
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ecryptfs_dentry->d_name.name, rc);
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make_bad_inode(inode);
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goto out_free_kmem;
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dentry->d_name.name, rc);
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return rc;
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}
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put_lower = 1;
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crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
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/* TODO: lock for crypt_stat comparison */
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if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED))
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ecryptfs_set_default_sizes(crypt_stat);
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rc = ecryptfs_read_and_validate_header_region(page_virt, inode);
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rc = ecryptfs_read_and_validate_header_region(inode);
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ecryptfs_put_lower_file(inode);
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if (rc) {
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memset(page_virt, 0, PAGE_CACHE_SIZE);
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rc = ecryptfs_read_and_validate_xattr_region(page_virt,
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inode);
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if (rc) {
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rc = 0;
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goto unlock_inode;
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}
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rc = ecryptfs_read_and_validate_xattr_region(dentry, inode);
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if (!rc)
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crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
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}
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ecryptfs_i_size_init(page_virt, inode);
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unlock_inode:
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if (inode->i_state & I_NEW)
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unlock_new_inode(inode);
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d_add(ecryptfs_dentry, inode);
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out_free_kmem:
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kmem_cache_free(ecryptfs_header_cache_2, page_virt);
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goto out;
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out_put:
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/* Must return 0 to allow non-eCryptfs files to be looked up, too */
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return 0;
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}
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/**
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* ecryptfs_lookup_interpose - Dentry interposition for a lookup
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*/
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static int ecryptfs_lookup_interpose(struct dentry *dentry,
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struct dentry *lower_dentry,
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struct inode *dir_inode)
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{
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struct inode *inode, *lower_inode = lower_dentry->d_inode;
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struct ecryptfs_dentry_info *dentry_info;
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struct vfsmount *lower_mnt;
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int rc = 0;
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lower_mnt = mntget(ecryptfs_dentry_to_lower_mnt(dentry->d_parent));
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fsstack_copy_attr_atime(dir_inode, lower_dentry->d_parent->d_inode);
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BUG_ON(!lower_dentry->d_count);
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dentry_info = kmem_cache_alloc(ecryptfs_dentry_info_cache, GFP_KERNEL);
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ecryptfs_set_dentry_private(dentry, dentry_info);
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if (!dentry_info) {
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printk(KERN_ERR "%s: Out of memory whilst attempting "
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"to allocate ecryptfs_dentry_info struct\n",
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__func__);
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dput(lower_dentry);
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mntput(lower_mnt);
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d_drop(ecryptfs_dentry);
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out:
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if (put_lower)
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ecryptfs_put_lower_file(inode);
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d_drop(dentry);
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return -ENOMEM;
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}
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ecryptfs_set_dentry_lower(dentry, lower_dentry);
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ecryptfs_set_dentry_lower_mnt(dentry, lower_mnt);
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if (!lower_dentry->d_inode) {
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/* We want to add because we couldn't find in lower */
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d_add(dentry, NULL);
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return 0;
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}
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inode = __ecryptfs_get_inode(lower_inode, dir_inode->i_sb);
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if (IS_ERR(inode)) {
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printk(KERN_ERR "%s: Error interposing; rc = [%ld]\n",
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__func__, PTR_ERR(inode));
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return PTR_ERR(inode);
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}
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if (S_ISREG(inode->i_mode)) {
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rc = ecryptfs_i_size_read(dentry, inode);
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if (rc) {
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make_bad_inode(inode);
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return rc;
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}
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}
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if (inode->i_state & I_NEW)
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unlock_new_inode(inode);
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d_add(dentry, inode);
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return rc;
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}
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