diff options
Diffstat (limited to 'fs/ecryptfs/crypto.c')
| -rw-r--r-- | fs/ecryptfs/crypto.c | 2111 |
1 files changed, 2111 insertions, 0 deletions
diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c new file mode 100644 index 000000000..adf070726 --- /dev/null +++ b/fs/ecryptfs/crypto.c @@ -0,0 +1,2111 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/** + * eCryptfs: Linux filesystem encryption layer + * + * Copyright (C) 1997-2004 Erez Zadok + * Copyright (C) 2001-2004 Stony Brook University + * Copyright (C) 2004-2007 International Business Machines Corp. + * Author(s): Michael A. Halcrow <mahalcro@us.ibm.com> + * Michael C. Thompson <mcthomps@us.ibm.com> + */ + +#include <crypto/hash.h> +#include <crypto/skcipher.h> +#include <linux/fs.h> +#include <linux/mount.h> +#include <linux/pagemap.h> +#include <linux/random.h> +#include <linux/compiler.h> +#include <linux/key.h> +#include <linux/namei.h> +#include <linux/file.h> +#include <linux/scatterlist.h> +#include <linux/slab.h> +#include <asm/unaligned.h> +#include <linux/kernel.h> +#include <linux/xattr.h> +#include "ecryptfs_kernel.h" + +#define DECRYPT 0 +#define ENCRYPT 1 + +/** + * ecryptfs_from_hex + * @dst: Buffer to take the bytes from src hex; must be at least of + * size (src_size / 2) + * @src: Buffer to be converted from a hex string representation to raw value + * @dst_size: size of dst buffer, or number of hex characters pairs to convert + */ +void ecryptfs_from_hex(char *dst, char *src, int dst_size) +{ + int x; + char tmp[3] = { 0, }; + + for (x = 0; x < dst_size; x++) { + tmp[0] = src[x * 2]; + tmp[1] = src[x * 2 + 1]; + dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16); + } +} + +/** + * ecryptfs_calculate_md5 - calculates the md5 of @src + * @dst: Pointer to 16 bytes of allocated memory + * @crypt_stat: Pointer to crypt_stat struct for the current inode + * @src: Data to be md5'd + * @len: Length of @src + * + * Uses the allocated crypto context that crypt_stat references to + * generate the MD5 sum of the contents of src. + */ +static int ecryptfs_calculate_md5(char *dst, + struct ecryptfs_crypt_stat *crypt_stat, + char *src, int len) +{ + int rc = crypto_shash_tfm_digest(crypt_stat->hash_tfm, src, len, dst); + + if (rc) { + printk(KERN_ERR + "%s: Error computing crypto hash; rc = [%d]\n", + __func__, rc); + goto out; + } +out: + return rc; +} + +static int ecryptfs_crypto_api_algify_cipher_name(char **algified_name, + char *cipher_name, + char *chaining_modifier) +{ + int cipher_name_len = strlen(cipher_name); + int chaining_modifier_len = strlen(chaining_modifier); + int algified_name_len; + int rc; + + algified_name_len = (chaining_modifier_len + cipher_name_len + 3); + (*algified_name) = kmalloc(algified_name_len, GFP_KERNEL); + if (!(*algified_name)) { + rc = -ENOMEM; + goto out; + } + snprintf((*algified_name), algified_name_len, "%s(%s)", + chaining_modifier, cipher_name); + rc = 0; +out: + return rc; +} + +/** + * ecryptfs_derive_iv + * @iv: destination for the derived iv vale + * @crypt_stat: Pointer to crypt_stat struct for the current inode + * @offset: Offset of the extent whose IV we are to derive + * + * Generate the initialization vector from the given root IV and page + * offset. + * + * Returns zero on success; non-zero on error. + */ +int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat, + loff_t offset) +{ + int rc = 0; + char dst[MD5_DIGEST_SIZE]; + char src[ECRYPTFS_MAX_IV_BYTES + 16]; + + if (unlikely(ecryptfs_verbosity > 0)) { + ecryptfs_printk(KERN_DEBUG, "root iv:\n"); + ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes); + } + /* TODO: It is probably secure to just cast the least + * significant bits of the root IV into an unsigned long and + * add the offset to that rather than go through all this + * hashing business. -Halcrow */ + memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes); + memset((src + crypt_stat->iv_bytes), 0, 16); + snprintf((src + crypt_stat->iv_bytes), 16, "%lld", offset); + if (unlikely(ecryptfs_verbosity > 0)) { + ecryptfs_printk(KERN_DEBUG, "source:\n"); + ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16)); + } + rc = ecryptfs_calculate_md5(dst, crypt_stat, src, + (crypt_stat->iv_bytes + 16)); + if (rc) { + ecryptfs_printk(KERN_WARNING, "Error attempting to compute " + "MD5 while generating IV for a page\n"); + goto out; + } + memcpy(iv, dst, crypt_stat->iv_bytes); + if (unlikely(ecryptfs_verbosity > 0)) { + ecryptfs_printk(KERN_DEBUG, "derived iv:\n"); + ecryptfs_dump_hex(iv, crypt_stat->iv_bytes); + } +out: + return rc; +} + +/** + * ecryptfs_init_crypt_stat + * @crypt_stat: Pointer to the crypt_stat struct to initialize. + * + * Initialize the crypt_stat structure. + */ +int ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat) +{ + struct crypto_shash *tfm; + int rc; + + tfm = crypto_alloc_shash(ECRYPTFS_DEFAULT_HASH, 0, 0); + if (IS_ERR(tfm)) { + rc = PTR_ERR(tfm); + ecryptfs_printk(KERN_ERR, "Error attempting to " + "allocate crypto context; rc = [%d]\n", + rc); + return rc; + } + + memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat)); + INIT_LIST_HEAD(&crypt_stat->keysig_list); + mutex_init(&crypt_stat->keysig_list_mutex); + mutex_init(&crypt_stat->cs_mutex); + mutex_init(&crypt_stat->cs_tfm_mutex); + crypt_stat->hash_tfm = tfm; + crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED; + + return 0; +} + +/** + * ecryptfs_destroy_crypt_stat + * @crypt_stat: Pointer to the crypt_stat struct to initialize. + * + * Releases all memory associated with a crypt_stat struct. + */ +void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat) +{ + struct ecryptfs_key_sig *key_sig, *key_sig_tmp; + + crypto_free_skcipher(crypt_stat->tfm); + crypto_free_shash(crypt_stat->hash_tfm); + list_for_each_entry_safe(key_sig, key_sig_tmp, + &crypt_stat->keysig_list, crypt_stat_list) { + list_del(&key_sig->crypt_stat_list); + kmem_cache_free(ecryptfs_key_sig_cache, key_sig); + } + memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat)); +} + +void ecryptfs_destroy_mount_crypt_stat( + struct ecryptfs_mount_crypt_stat *mount_crypt_stat) +{ + struct ecryptfs_global_auth_tok *auth_tok, *auth_tok_tmp; + + if (!(mount_crypt_stat->flags & ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED)) + return; + mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex); + list_for_each_entry_safe(auth_tok, auth_tok_tmp, + &mount_crypt_stat->global_auth_tok_list, + mount_crypt_stat_list) { + list_del(&auth_tok->mount_crypt_stat_list); + if (!(auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID)) + key_put(auth_tok->global_auth_tok_key); + kmem_cache_free(ecryptfs_global_auth_tok_cache, auth_tok); + } + mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex); + memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat)); +} + +/** + * virt_to_scatterlist + * @addr: Virtual address + * @size: Size of data; should be an even multiple of the block size + * @sg: Pointer to scatterlist array; set to NULL to obtain only + * the number of scatterlist structs required in array + * @sg_size: Max array size + * + * Fills in a scatterlist array with page references for a passed + * virtual address. + * + * Returns the number of scatterlist structs in array used + */ +int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg, + int sg_size) +{ + int i = 0; + struct page *pg; + int offset; + int remainder_of_page; + + sg_init_table(sg, sg_size); + + while (size > 0 && i < sg_size) { + pg = virt_to_page(addr); + offset = offset_in_page(addr); + sg_set_page(&sg[i], pg, 0, offset); + remainder_of_page = PAGE_SIZE - offset; + if (size >= remainder_of_page) { + sg[i].length = remainder_of_page; + addr += remainder_of_page; + size -= remainder_of_page; + } else { + sg[i].length = size; + addr += size; + size = 0; + } + i++; + } + if (size > 0) + return -ENOMEM; + return i; +} + +struct extent_crypt_result { + struct completion completion; + int rc; +}; + +static void extent_crypt_complete(struct crypto_async_request *req, int rc) +{ + struct extent_crypt_result *ecr = req->data; + + if (rc == -EINPROGRESS) + return; + + ecr->rc = rc; + complete(&ecr->completion); +} + +/** + * crypt_scatterlist + * @crypt_stat: Pointer to the crypt_stat struct to initialize. + * @dst_sg: Destination of the data after performing the crypto operation + * @src_sg: Data to be encrypted or decrypted + * @size: Length of data + * @iv: IV to use + * @op: ENCRYPT or DECRYPT to indicate the desired operation + * + * Returns the number of bytes encrypted or decrypted; negative value on error + */ +static int crypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat, + struct scatterlist *dst_sg, + struct scatterlist *src_sg, int size, + unsigned char *iv, int op) +{ + struct skcipher_request *req = NULL; + struct extent_crypt_result ecr; + int rc = 0; + + BUG_ON(!crypt_stat || !crypt_stat->tfm + || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED)); + if (unlikely(ecryptfs_verbosity > 0)) { + ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n", + crypt_stat->key_size); + ecryptfs_dump_hex(crypt_stat->key, + crypt_stat->key_size); + } + + init_completion(&ecr.completion); + + mutex_lock(&crypt_stat->cs_tfm_mutex); + req = skcipher_request_alloc(crypt_stat->tfm, GFP_NOFS); + if (!req) { + mutex_unlock(&crypt_stat->cs_tfm_mutex); + rc = -ENOMEM; + goto out; + } + + skcipher_request_set_callback(req, + CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, + extent_crypt_complete, &ecr); + /* Consider doing this once, when the file is opened */ + if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) { + rc = crypto_skcipher_setkey(crypt_stat->tfm, crypt_stat->key, + crypt_stat->key_size); + if (rc) { + ecryptfs_printk(KERN_ERR, + "Error setting key; rc = [%d]\n", + rc); + mutex_unlock(&crypt_stat->cs_tfm_mutex); + rc = -EINVAL; + goto out; + } + crypt_stat->flags |= ECRYPTFS_KEY_SET; + } + mutex_unlock(&crypt_stat->cs_tfm_mutex); + skcipher_request_set_crypt(req, src_sg, dst_sg, size, iv); + rc = op == ENCRYPT ? crypto_skcipher_encrypt(req) : + crypto_skcipher_decrypt(req); + if (rc == -EINPROGRESS || rc == -EBUSY) { + struct extent_crypt_result *ecr = req->base.data; + + wait_for_completion(&ecr->completion); + rc = ecr->rc; + reinit_completion(&ecr->completion); + } +out: + skcipher_request_free(req); + return rc; +} + +/** + * lower_offset_for_page + * + * Convert an eCryptfs page index into a lower byte offset + */ +static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat, + struct page *page) +{ + return ecryptfs_lower_header_size(crypt_stat) + + ((loff_t)page->index << PAGE_SHIFT); +} + +/** + * crypt_extent + * @crypt_stat: crypt_stat containing cryptographic context for the + * encryption operation + * @dst_page: The page to write the result into + * @src_page: The page to read from + * @extent_offset: Page extent offset for use in generating IV + * @op: ENCRYPT or DECRYPT to indicate the desired operation + * + * Encrypts or decrypts one extent of data. + * + * Return zero on success; non-zero otherwise + */ +static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat, + struct page *dst_page, + struct page *src_page, + unsigned long extent_offset, int op) +{ + pgoff_t page_index = op == ENCRYPT ? src_page->index : dst_page->index; + loff_t extent_base; + char extent_iv[ECRYPTFS_MAX_IV_BYTES]; + struct scatterlist src_sg, dst_sg; + size_t extent_size = crypt_stat->extent_size; + int rc; + + extent_base = (((loff_t)page_index) * (PAGE_SIZE / extent_size)); + rc = ecryptfs_derive_iv(extent_iv, crypt_stat, + (extent_base + extent_offset)); + if (rc) { + ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for " + "extent [0x%.16llx]; rc = [%d]\n", + (unsigned long long)(extent_base + extent_offset), rc); + goto out; + } + + sg_init_table(&src_sg, 1); + sg_init_table(&dst_sg, 1); + + sg_set_page(&src_sg, src_page, extent_size, + extent_offset * extent_size); + sg_set_page(&dst_sg, dst_page, extent_size, + extent_offset * extent_size); + + rc = crypt_scatterlist(crypt_stat, &dst_sg, &src_sg, extent_size, + extent_iv, op); + if (rc < 0) { + printk(KERN_ERR "%s: Error attempting to crypt page with " + "page_index = [%ld], extent_offset = [%ld]; " + "rc = [%d]\n", __func__, page_index, extent_offset, rc); + goto out; + } + rc = 0; +out: + return rc; +} + +/** + * ecryptfs_encrypt_page + * @page: Page mapped from the eCryptfs inode for the file; contains + * decrypted content that needs to be encrypted (to a temporary + * page; not in place) and written out to the lower file + * + * Encrypt an eCryptfs page. This is done on a per-extent basis. Note + * that eCryptfs pages may straddle the lower pages -- for instance, + * if the file was created on a machine with an 8K page size + * (resulting in an 8K header), and then the file is copied onto a + * host with a 32K page size, then when reading page 0 of the eCryptfs + * file, 24K of page 0 of the lower file will be read and decrypted, + * and then 8K of page 1 of the lower file will be read and decrypted. + * + * Returns zero on success; negative on error + */ +int ecryptfs_encrypt_page(struct page *page) +{ + struct inode *ecryptfs_inode; + struct ecryptfs_crypt_stat *crypt_stat; + char *enc_extent_virt; + struct page *enc_extent_page = NULL; + loff_t extent_offset; + loff_t lower_offset; + int rc = 0; + + ecryptfs_inode = page->mapping->host; + crypt_stat = + &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat); + BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)); + enc_extent_page = alloc_page(GFP_USER); + if (!enc_extent_page) { + rc = -ENOMEM; + ecryptfs_printk(KERN_ERR, "Error allocating memory for " + "encrypted extent\n"); + goto out; + } + + for (extent_offset = 0; + extent_offset < (PAGE_SIZE / crypt_stat->extent_size); + extent_offset++) { + rc = crypt_extent(crypt_stat, enc_extent_page, page, + extent_offset, ENCRYPT); + if (rc) { + printk(KERN_ERR "%s: Error encrypting extent; " + "rc = [%d]\n", __func__, rc); + goto out; + } + } + + lower_offset = lower_offset_for_page(crypt_stat, page); + enc_extent_virt = kmap(enc_extent_page); + rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset, + PAGE_SIZE); + kunmap(enc_extent_page); + if (rc < 0) { + ecryptfs_printk(KERN_ERR, + "Error attempting to write lower page; rc = [%d]\n", + rc); + goto out; + } + rc = 0; +out: + if (enc_extent_page) { + __free_page(enc_extent_page); + } + return rc; +} + +/** + * ecryptfs_decrypt_page + * @page: Page mapped from the eCryptfs inode for the file; data read + * and decrypted from the lower file will be written into this + * page + * + * Decrypt an eCryptfs page. This is done on a per-extent basis. Note + * that eCryptfs pages may straddle the lower pages -- for instance, + * if the file was created on a machine with an 8K page size + * (resulting in an 8K header), and then the file is copied onto a + * host with a 32K page size, then when reading page 0 of the eCryptfs + * file, 24K of page 0 of the lower file will be read and decrypted, + * and then 8K of page 1 of the lower file will be read and decrypted. + * + * Returns zero on success; negative on error + */ +int ecryptfs_decrypt_page(struct page *page) +{ + struct inode *ecryptfs_inode; + struct ecryptfs_crypt_stat *crypt_stat; + char *page_virt; + unsigned long extent_offset; + loff_t lower_offset; + int rc = 0; + + ecryptfs_inode = page->mapping->host; + crypt_stat = + &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat); + BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)); + + lower_offset = lower_offset_for_page(crypt_stat, page); + page_virt = kmap(page); + rc = ecryptfs_read_lower(page_virt, lower_offset, PAGE_SIZE, + ecryptfs_inode); + kunmap(page); + if (rc < 0) { + ecryptfs_printk(KERN_ERR, + "Error attempting to read lower page; rc = [%d]\n", + rc); + goto out; + } + + for (extent_offset = 0; + extent_offset < (PAGE_SIZE / crypt_stat->extent_size); + extent_offset++) { + rc = crypt_extent(crypt_stat, page, page, + extent_offset, DECRYPT); + if (rc) { + printk(KERN_ERR "%s: Error encrypting extent; " + "rc = [%d]\n", __func__, rc); + goto out; + } + } +out: + return rc; +} + +#define ECRYPTFS_MAX_SCATTERLIST_LEN 4 + +/** + * ecryptfs_init_crypt_ctx + * @crypt_stat: Uninitialized crypt stats structure + * + * Initialize the crypto context. + * + * TODO: Performance: Keep a cache of initialized cipher contexts; + * only init if needed + */ +int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat) +{ + char *full_alg_name; + int rc = -EINVAL; + + ecryptfs_printk(KERN_DEBUG, + "Initializing cipher [%s]; strlen = [%d]; " + "key_size_bits = [%zd]\n", + crypt_stat->cipher, (int)strlen(crypt_stat->cipher), + crypt_stat->key_size << 3); + mutex_lock(&crypt_stat->cs_tfm_mutex); + if (crypt_stat->tfm) { + rc = 0; + goto out_unlock; + } + rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, + crypt_stat->cipher, "cbc"); + if (rc) + goto out_unlock; + crypt_stat->tfm = crypto_alloc_skcipher(full_alg_name, 0, 0); + if (IS_ERR(crypt_stat->tfm)) { + rc = PTR_ERR(crypt_stat->tfm); + crypt_stat->tfm = NULL; + ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): " + "Error initializing cipher [%s]\n", + full_alg_name); + goto out_free; + } + crypto_skcipher_set_flags(crypt_stat->tfm, + CRYPTO_TFM_REQ_FORBID_WEAK_KEYS); + rc = 0; +out_free: + kfree(full_alg_name); +out_unlock: + mutex_unlock(&crypt_stat->cs_tfm_mutex); + return rc; +} + +static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat) +{ + int extent_size_tmp; + + crypt_stat->extent_mask = 0xFFFFFFFF; + crypt_stat->extent_shift = 0; + if (crypt_stat->extent_size == 0) + return; + extent_size_tmp = crypt_stat->extent_size; + while ((extent_size_tmp & 0x01) == 0) { + extent_size_tmp >>= 1; + crypt_stat->extent_mask <<= 1; + crypt_stat->extent_shift++; + } +} + +void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat) +{ + /* Default values; may be overwritten as we are parsing the + * packets. */ + crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE; + 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->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE; + else { + if (PAGE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) + crypt_stat->metadata_size = + ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE; + else + crypt_stat->metadata_size = PAGE_SIZE; + } +} + +/** + * ecryptfs_compute_root_iv + * @crypt_stats + * + * On error, sets the root IV to all 0's. + */ +int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat) +{ + int rc = 0; + char dst[MD5_DIGEST_SIZE]; + + BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE); + BUG_ON(crypt_stat->iv_bytes <= 0); + if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) { + rc = -EINVAL; + ecryptfs_printk(KERN_WARNING, "Session key not valid; " + "cannot generate root IV\n"); + goto out; + } + rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key, + crypt_stat->key_size); + if (rc) { + ecryptfs_printk(KERN_WARNING, "Error attempting to compute " + "MD5 while generating root IV\n"); + goto out; + } + memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes); +out: + if (rc) { + memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes); + crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING; + } + return rc; +} + +static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat) +{ + get_random_bytes(crypt_stat->key, crypt_stat->key_size); + crypt_stat->flags |= ECRYPTFS_KEY_VALID; + ecryptfs_compute_root_iv(crypt_stat); + if (unlikely(ecryptfs_verbosity > 0)) { + ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n"); + ecryptfs_dump_hex(crypt_stat->key, + crypt_stat->key_size); + } +} + +/** + * ecryptfs_copy_mount_wide_flags_to_inode_flags + * @crypt_stat: The inode's cryptographic context + * @mount_crypt_stat: The mount point's cryptographic context + * + * This function propagates the mount-wide flags to individual inode + * flags. + */ +static void ecryptfs_copy_mount_wide_flags_to_inode_flags( + struct ecryptfs_crypt_stat *crypt_stat, + struct ecryptfs_mount_crypt_stat *mount_crypt_stat) +{ + if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) + crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR; + if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) + crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED; + if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) { + crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES; + if (mount_crypt_stat->flags + & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK) + crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK; + else if (mount_crypt_stat->flags + & ECRYPTFS_GLOBAL_ENCFN_USE_FEK) + crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK; + } +} + +static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs( + struct ecryptfs_crypt_stat *crypt_stat, + struct ecryptfs_mount_crypt_stat *mount_crypt_stat) +{ + struct ecryptfs_global_auth_tok *global_auth_tok; + int rc = 0; + + mutex_lock(&crypt_stat->keysig_list_mutex); + mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex); + + list_for_each_entry(global_auth_tok, + &mount_crypt_stat->global_auth_tok_list, + mount_crypt_stat_list) { + if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK) + continue; + rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig); + if (rc) { + printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc); + goto out; + } + } + +out: + mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex); + mutex_unlock(&crypt_stat->keysig_list_mutex); + return rc; +} + +/** + * ecryptfs_set_default_crypt_stat_vals + * @crypt_stat: The inode's cryptographic context + * @mount_crypt_stat: The mount point's cryptographic context + * + * Default values in the event that policy does not override them. + */ +static void ecryptfs_set_default_crypt_stat_vals( + struct ecryptfs_crypt_stat *crypt_stat, + struct ecryptfs_mount_crypt_stat *mount_crypt_stat) +{ + ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat, + mount_crypt_stat); + ecryptfs_set_default_sizes(crypt_stat); + strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER); + crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES; + crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID); + crypt_stat->file_version = ECRYPTFS_FILE_VERSION; + crypt_stat->mount_crypt_stat = mount_crypt_stat; +} + +/** + * ecryptfs_new_file_context + * @ecryptfs_inode: The eCryptfs inode + * + * If the crypto context for the file has not yet been established, + * this is where we do that. Establishing a new crypto context + * involves the following decisions: + * - What cipher to use? + * - What set of authentication tokens to use? + * Here we just worry about getting enough information into the + * authentication tokens so that we know that they are available. + * We associate the available authentication tokens with the new file + * via the set of signatures in the crypt_stat struct. Later, when + * the headers are actually written out, we may again defer to + * userspace to perform the encryption of the session key; for the + * foreseeable future, this will be the case with public key packets. + * + * Returns zero on success; non-zero otherwise + */ +int ecryptfs_new_file_context(struct inode *ecryptfs_inode) +{ + struct ecryptfs_crypt_stat *crypt_stat = + &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat; + struct ecryptfs_mount_crypt_stat *mount_crypt_stat = + &ecryptfs_superblock_to_private( + ecryptfs_inode->i_sb)->mount_crypt_stat; + int cipher_name_len; + int rc = 0; + + ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat); + crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID); + ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat, + mount_crypt_stat); + rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat, + mount_crypt_stat); + if (rc) { + printk(KERN_ERR "Error attempting to copy mount-wide key sigs " + "to the inode key sigs; rc = [%d]\n", rc); + goto out; + } + cipher_name_len = + strlen(mount_crypt_stat->global_default_cipher_name); + memcpy(crypt_stat->cipher, + mount_crypt_stat->global_default_cipher_name, + cipher_name_len); + crypt_stat->cipher[cipher_name_len] = '\0'; + crypt_stat->key_size = + mount_crypt_stat->global_default_cipher_key_size; + ecryptfs_generate_new_key(crypt_stat); + rc = ecryptfs_init_crypt_ctx(crypt_stat); + if (rc) + ecryptfs_printk(KERN_ERR, "Error initializing cryptographic " + "context for cipher [%s]: rc = [%d]\n", + crypt_stat->cipher, rc); +out: + return rc; +} + +/** + * ecryptfs_validate_marker - check for the ecryptfs marker + * @data: The data block in which to check + * + * Returns zero if marker found; -EINVAL if not found + */ +static int ecryptfs_validate_marker(char *data) +{ + u32 m_1, m_2; + + m_1 = get_unaligned_be32(data); + m_2 = get_unaligned_be32(data + 4); + if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2) + return 0; + ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; " + "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2, + MAGIC_ECRYPTFS_MARKER); + ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = " + "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER)); + return -EINVAL; +} + +struct ecryptfs_flag_map_elem { + u32 file_flag; + u32 local_flag; +}; + +/* Add support for additional flags by adding elements here. */ +static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = { + {0x00000001, ECRYPTFS_ENABLE_HMAC}, + {0x00000002, ECRYPTFS_ENCRYPTED}, + {0x00000004, ECRYPTFS_METADATA_IN_XATTR}, + {0x00000008, ECRYPTFS_ENCRYPT_FILENAMES} +}; + +/** + * ecryptfs_process_flags + * @crypt_stat: The cryptographic context + * @page_virt: Source data to be parsed + * @bytes_read: Updated with the number of bytes read + */ +static void ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat, + char *page_virt, int *bytes_read) +{ + int i; + u32 flags; + + flags = get_unaligned_be32(page_virt); + for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++) + if (flags & ecryptfs_flag_map[i].file_flag) { + crypt_stat->flags |= ecryptfs_flag_map[i].local_flag; + } else + crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag); + /* Version is in top 8 bits of the 32-bit flag vector */ + crypt_stat->file_version = ((flags >> 24) & 0xFF); + (*bytes_read) = 4; +} + +/** + * write_ecryptfs_marker + * @page_virt: The pointer to in a page to begin writing the marker + * @written: Number of bytes written + * + * Marker = 0x3c81b7f5 + */ +static void write_ecryptfs_marker(char *page_virt, size_t *written) +{ + u32 m_1, m_2; + + get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2)); + m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER); + put_unaligned_be32(m_1, page_virt); + page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2); + put_unaligned_be32(m_2, page_virt); + (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES; +} + +void ecryptfs_write_crypt_stat_flags(char *page_virt, + struct ecryptfs_crypt_stat *crypt_stat, + size_t *written) +{ + u32 flags = 0; + int i; + + for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++) + if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag) + flags |= ecryptfs_flag_map[i].file_flag; + /* Version is in top 8 bits of the 32-bit flag vector */ + flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000); + put_unaligned_be32(flags, page_virt); + (*written) = 4; +} + +struct ecryptfs_cipher_code_str_map_elem { + char cipher_str[16]; + u8 cipher_code; +}; + +/* Add support for additional ciphers by adding elements here. The + * cipher_code is whatever OpenPGP applications use to identify the + * ciphers. List in order of probability. */ +static struct ecryptfs_cipher_code_str_map_elem +ecryptfs_cipher_code_str_map[] = { + {"aes",RFC2440_CIPHER_AES_128 }, + {"blowfish", RFC2440_CIPHER_BLOWFISH}, + {"des3_ede", RFC2440_CIPHER_DES3_EDE}, + {"cast5", RFC2440_CIPHER_CAST_5}, + {"twofish", RFC2440_CIPHER_TWOFISH}, + {"cast6", RFC2440_CIPHER_CAST_6}, + {"aes", RFC2440_CIPHER_AES_192}, + {"aes", RFC2440_CIPHER_AES_256} +}; + +/** + * ecryptfs_code_for_cipher_string + * @cipher_name: The string alias for the cipher + * @key_bytes: Length of key in bytes; used for AES code selection + * + * Returns zero on no match, or the cipher code on match + */ +u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes) +{ + int i; + u8 code = 0; + struct ecryptfs_cipher_code_str_map_elem *map = + ecryptfs_cipher_code_str_map; + + if (strcmp(cipher_name, "aes") == 0) { + switch (key_bytes) { + case 16: + code = RFC2440_CIPHER_AES_128; + break; + case 24: + code = RFC2440_CIPHER_AES_192; + break; + case 32: + code = RFC2440_CIPHER_AES_256; + } + } else { + for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++) + if (strcmp(cipher_name, map[i].cipher_str) == 0) { + code = map[i].cipher_code; + break; + } + } + return code; +} + +/** + * ecryptfs_cipher_code_to_string + * @str: Destination to write out the cipher name + * @cipher_code: The code to convert to cipher name string + * + * Returns zero on success + */ +int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code) +{ + int rc = 0; + int i; + + str[0] = '\0'; + for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++) + if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code) + strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str); + if (str[0] == '\0') { + ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: " + "[%d]\n", cipher_code); + rc = -EINVAL; + } + return rc; +} + +int ecryptfs_read_and_validate_header_region(struct inode *inode) +{ + u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES]; + u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES; + int rc; + + rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES, + inode); + if (rc < 0) + return rc; + else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES) + return -EINVAL; + rc = ecryptfs_validate_marker(marker); + if (!rc) + ecryptfs_i_size_init(file_size, inode); + return rc; +} + +void +ecryptfs_write_header_metadata(char *virt, + struct ecryptfs_crypt_stat *crypt_stat, + size_t *written) +{ + u32 header_extent_size; + u16 num_header_extents_at_front; + + header_extent_size = (u32)crypt_stat->extent_size; + num_header_extents_at_front = + (u16)(crypt_stat->metadata_size / crypt_stat->extent_size); + put_unaligned_be32(header_extent_size, virt); + virt += 4; + put_unaligned_be16(num_header_extents_at_front, virt); + (*written) = 6; +} + +struct kmem_cache *ecryptfs_header_cache; + +/** + * ecryptfs_write_headers_virt + * @page_virt: The virtual address to write the headers to + * @max: The size of memory allocated at page_virt + * @size: Set to the number of bytes written by this function + * @crypt_stat: The cryptographic context + * @ecryptfs_dentry: The eCryptfs dentry + * + * Format version: 1 + * + * Header Extent: + * Octets 0-7: Unencrypted file size (big-endian) + * Octets 8-15: eCryptfs special marker + * Octets 16-19: Flags + * Octet 16: File format version number (between 0 and 255) + * Octets 17-18: Reserved + * Octet 19: Bit 1 (lsb): Reserved + * Bit 2: Encrypted? + * Bits 3-8: Reserved + * Octets 20-23: Header extent size (big-endian) + * Octets 24-25: Number of header extents at front of file + * (big-endian) + * Octet 26: Begin RFC 2440 authentication token packet set + * Data Extent 0: + * Lower data (CBC encrypted) + * Data Extent 1: + * Lower data (CBC encrypted) + * ... + * + * Returns zero on success + */ +static int ecryptfs_write_headers_virt(char *page_virt, size_t max, + size_t *size, + struct ecryptfs_crypt_stat *crypt_stat, + struct dentry *ecryptfs_dentry) +{ + int rc; + size_t written; + size_t offset; + + offset = ECRYPTFS_FILE_SIZE_BYTES; + write_ecryptfs_marker((page_virt + offset), &written); + offset += written; + ecryptfs_write_crypt_stat_flags((page_virt + offset), crypt_stat, + &written); + offset += written; + ecryptfs_write_header_metadata((page_virt + offset), crypt_stat, + &written); + offset += written; + rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat, + ecryptfs_dentry, &written, + max - offset); + if (rc) + ecryptfs_printk(KERN_WARNING, "Error generating key packet " + "set; rc = [%d]\n", rc); + if (size) { + offset += written; + *size = offset; + } + return rc; +} + +static int +ecryptfs_write_metadata_to_contents(struct inode *ecryptfs_inode, + char *virt, size_t virt_len) +{ + int rc; + + rc = ecryptfs_write_lower(ecryptfs_inode, virt, + 0, virt_len); + if (rc < 0) + printk(KERN_ERR "%s: Error attempting to write header " + "information to lower file; rc = [%d]\n", __func__, rc); + else + rc = 0; + return rc; +} + +static int +ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry, + struct inode *ecryptfs_inode, + char *page_virt, size_t size) +{ + int rc; + struct dentry *lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry); + struct inode *lower_inode = d_inode(lower_dentry); + + if (!(lower_inode->i_opflags & IOP_XATTR)) { + rc = -EOPNOTSUPP; + goto out; + } + + inode_lock(lower_inode); + rc = __vfs_setxattr(lower_dentry, lower_inode, ECRYPTFS_XATTR_NAME, + page_virt, size, 0); + if (!rc && ecryptfs_inode) + fsstack_copy_attr_all(ecryptfs_inode, lower_inode); + inode_unlock(lower_inode); +out: + return rc; +} + +static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask, + unsigned int order) +{ + struct page *page; + + page = alloc_pages(gfp_mask | __GFP_ZERO, order); + if (page) + return (unsigned long) page_address(page); + return 0; +} + +/** + * ecryptfs_write_metadata + * @ecryptfs_dentry: The eCryptfs dentry, which should be negative + * @ecryptfs_inode: The newly created eCryptfs inode + * + * Write the file headers out. This will likely involve a userspace + * callout, in which the session key is encrypted with one or more + * public keys and/or the passphrase necessary to do the encryption is + * retrieved via a prompt. Exactly what happens at this point should + * be policy-dependent. + * + * Returns zero on success; non-zero on error + */ +int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry, + struct inode *ecryptfs_inode) +{ + struct ecryptfs_crypt_stat *crypt_stat = + &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat; + unsigned int order; + char *virt; + size_t virt_len; + size_t size = 0; + int rc = 0; + + if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) { + if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) { + printk(KERN_ERR "Key is invalid; bailing out\n"); + rc = -EINVAL; + goto out; + } + } else { + printk(KERN_WARNING "%s: Encrypted flag not set\n", + __func__); + rc = -EINVAL; + goto out; + } + virt_len = crypt_stat->metadata_size; + order = get_order(virt_len); + /* Released in this function */ + virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order); + if (!virt) { + printk(KERN_ERR "%s: Out of memory\n", __func__); + rc = -ENOMEM; + goto out; + } + /* Zeroed page ensures the in-header unencrypted i_size is set to 0 */ + rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat, + ecryptfs_dentry); + if (unlikely(rc)) { + printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n", + __func__, rc); + goto out_free; + } + if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) + rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, ecryptfs_inode, + virt, size); + else + rc = ecryptfs_write_metadata_to_contents(ecryptfs_inode, virt, + virt_len); + if (rc) { + printk(KERN_ERR "%s: Error writing metadata out to lower file; " + "rc = [%d]\n", __func__, rc); + goto out_free; + } +out_free: + free_pages((unsigned long)virt, order); +out: + return rc; +} + +#define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0 +#define ECRYPTFS_VALIDATE_HEADER_SIZE 1 +static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat, + char *virt, int *bytes_read, + int validate_header_size) +{ + int rc = 0; + u32 header_extent_size; + u16 num_header_extents_at_front; + + header_extent_size = get_unaligned_be32(virt); + virt += sizeof(__be32); + num_header_extents_at_front = get_unaligned_be16(virt); + crypt_stat->metadata_size = (((size_t)num_header_extents_at_front + * (size_t)header_extent_size)); + (*bytes_read) = (sizeof(__be32) + sizeof(__be16)); + if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE) + && (crypt_stat->metadata_size + < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) { + rc = -EINVAL; + printk(KERN_WARNING "Invalid header size: [%zd]\n", + crypt_stat->metadata_size); + } + return rc; +} + +/** + * set_default_header_data + * @crypt_stat: The cryptographic context + * + * For version 0 file format; this function is only for backwards + * compatibility for files created with the prior versions of + * eCryptfs. + */ +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 + * @crypt_stat: The cryptographic context + * @ecryptfs_dentry: The eCryptfs dentry + * @validate_header_size: Whether to validate the header size while reading + * + * Read/parse the header data. The header format is detailed in the + * comment block for the ecryptfs_write_headers_virt() function. + * + * Returns zero on success + */ +static int ecryptfs_read_headers_virt(char *page_virt, + struct ecryptfs_crypt_stat *crypt_stat, + struct dentry *ecryptfs_dentry, + int validate_header_size) +{ + int rc = 0; + int offset; + int bytes_read; + + ecryptfs_set_default_sizes(crypt_stat); + crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private( + ecryptfs_dentry->d_sb)->mount_crypt_stat; + offset = ECRYPTFS_FILE_SIZE_BYTES; + rc = ecryptfs_validate_marker(page_virt + offset); + if (rc) + goto out; + if (!(crypt_stat->flags & ECRYPTFS_I_SIZE_INITIALIZED)) + ecryptfs_i_size_init(page_virt, d_inode(ecryptfs_dentry)); + offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES; + ecryptfs_process_flags(crypt_stat, (page_virt + offset), &bytes_read); + if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) { + ecryptfs_printk(KERN_WARNING, "File version is [%d]; only " + "file version [%d] is supported by this " + "version of eCryptfs\n", + crypt_stat->file_version, + ECRYPTFS_SUPPORTED_FILE_VERSION); + rc = -EINVAL; + goto out; + } + offset += bytes_read; + if (crypt_stat->file_version >= 1) { + rc = parse_header_metadata(crypt_stat, (page_virt + offset), + &bytes_read, validate_header_size); + if (rc) { + ecryptfs_printk(KERN_WARNING, "Error reading header " + "metadata; rc = [%d]\n", rc); + } + offset += bytes_read; + } else + set_default_header_data(crypt_stat); + rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset), + ecryptfs_dentry); +out: + return rc; +} + +/** + * ecryptfs_read_xattr_region + * @page_virt: The vitual address into which to read the xattr data + * @ecryptfs_inode: The eCryptfs inode + * + * Attempts to read the crypto metadata from the extended attribute + * region of the lower file. + * + * Returns zero on success; non-zero on error + */ +int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode) +{ + struct dentry *lower_dentry = + ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_path.dentry; + ssize_t size; + int rc = 0; + + size = ecryptfs_getxattr_lower(lower_dentry, + ecryptfs_inode_to_lower(ecryptfs_inode), + ECRYPTFS_XATTR_NAME, + page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE); + if (size < 0) { + if (unlikely(ecryptfs_verbosity > 0)) + printk(KERN_INFO "Error attempting to read the [%s] " + "xattr from the lower file; return value = " + "[%zd]\n", ECRYPTFS_XATTR_NAME, size); + rc = -EINVAL; + goto out; + } +out: + return rc; +} + +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_getxattr_lower(ecryptfs_dentry_to_lower(dentry), + ecryptfs_inode_to_lower(inode), + ECRYPTFS_XATTR_NAME, file_size, + ECRYPTFS_SIZE_AND_MARKER_BYTES); + if (rc < 0) + return rc; + else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES) + return -EINVAL; + rc = ecryptfs_validate_marker(marker); + if (!rc) + ecryptfs_i_size_init(file_size, inode); + return rc; +} + +/** + * ecryptfs_read_metadata + * + * Common entry point for reading file metadata. From here, we could + * retrieve the header information from the header region of the file, + * the xattr region of the file, or some other repository that is + * stored separately from the file itself. The current implementation + * supports retrieving the metadata information from the file contents + * and from the xattr region. + * + * Returns zero if valid headers found and parsed; non-zero otherwise + */ +int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry) +{ + int rc; + char *page_virt; + struct inode *ecryptfs_inode = d_inode(ecryptfs_dentry); + struct ecryptfs_crypt_stat *crypt_stat = + &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat; + struct ecryptfs_mount_crypt_stat *mount_crypt_stat = + &ecryptfs_superblock_to_private( + ecryptfs_dentry->d_sb)->mount_crypt_stat; + + ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat, + mount_crypt_stat); + /* Read the first page from the underlying file */ + page_virt = kmem_cache_alloc(ecryptfs_header_cache, GFP_USER); + if (!page_virt) { + rc = -ENOMEM; + goto out; + } + rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size, + ecryptfs_inode); + if (rc >= 0) + rc = ecryptfs_read_headers_virt(page_virt, crypt_stat, + ecryptfs_dentry, + ECRYPTFS_VALIDATE_HEADER_SIZE); + if (rc) { + /* metadata is not in the file header, so try xattrs */ + memset(page_virt, 0, PAGE_SIZE); + rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode); + if (rc) { + printk(KERN_DEBUG "Valid eCryptfs headers not found in " + "file header region or xattr region, inode %lu\n", + ecryptfs_inode->i_ino); + rc = -EINVAL; + goto out; + } + rc = ecryptfs_read_headers_virt(page_virt, crypt_stat, + ecryptfs_dentry, + ECRYPTFS_DONT_VALIDATE_HEADER_SIZE); + if (rc) { + printk(KERN_DEBUG "Valid eCryptfs headers not found in " + "file xattr region either, inode %lu\n", + ecryptfs_inode->i_ino); + rc = -EINVAL; + } + if (crypt_stat->mount_crypt_stat->flags + & ECRYPTFS_XATTR_METADATA_ENABLED) { + crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR; + } else { + printk(KERN_WARNING "Attempt to access file with " + "crypto metadata only in the extended attribute " + "region, but eCryptfs was mounted without " + "xattr support enabled. eCryptfs will not treat " + "this like an encrypted file, inode %lu\n", + ecryptfs_inode->i_ino); + rc = -EINVAL; + } + } +out: + if (page_virt) { + memset(page_virt, 0, PAGE_SIZE); + kmem_cache_free(ecryptfs_header_cache, page_virt); + } + return rc; +} + +/** + * ecryptfs_encrypt_filename - encrypt filename + * + * CBC-encrypts the filename. We do not want to encrypt the same + * filename with the same key and IV, which may happen with hard + * links, so we prepend random bits to each filename. + * + * Returns zero on success; non-zero otherwise + */ +static int +ecryptfs_encrypt_filename(struct ecryptfs_filename *filename, + struct ecryptfs_mount_crypt_stat *mount_crypt_stat) +{ + int rc = 0; + + filename->encrypted_filename = NULL; + filename->encrypted_filename_size = 0; + if (mount_crypt_stat && (mount_crypt_stat->flags + & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) { + size_t packet_size; + size_t remaining_bytes; + + rc = ecryptfs_write_tag_70_packet( + NULL, NULL, + &filename->encrypted_filename_size, + mount_crypt_stat, NULL, + filename->filename_size); + if (rc) { + printk(KERN_ERR "%s: Error attempting to get packet " + "size for tag 72; rc = [%d]\n", __func__, + rc); + filename->encrypted_filename_size = 0; + goto out; + } + filename->encrypted_filename = + kmalloc(filename->encrypted_filename_size, GFP_KERNEL); + if (!filename->encrypted_filename) { + rc = -ENOMEM; + goto out; + } + remaining_bytes = filename->encrypted_filename_size; + rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename, + &remaining_bytes, + &packet_size, + mount_crypt_stat, + filename->filename, + filename->filename_size); + if (rc) { + printk(KERN_ERR "%s: Error attempting to generate " + "tag 70 packet; rc = [%d]\n", __func__, + rc); + kfree(filename->encrypted_filename); + filename->encrypted_filename = NULL; + filename->encrypted_filename_size = 0; + goto out; + } + filename->encrypted_filename_size = packet_size; + } else { + printk(KERN_ERR "%s: No support for requested filename " + "encryption method in this release\n", __func__); + rc = -EOPNOTSUPP; + goto out; + } +out: + return rc; +} + +static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size, + const char *name, size_t name_size) +{ + int rc = 0; + + (*copied_name) = kmalloc((name_size + 1), GFP_KERNEL); + if (!(*copied_name)) { + rc = -ENOMEM; + goto out; + } + memcpy((void *)(*copied_name), (void *)name, name_size); + (*copied_name)[(name_size)] = '\0'; /* Only for convenience + * in printing out the + * string in debug + * messages */ + (*copied_name_size) = name_size; +out: + return rc; +} + +/** + * ecryptfs_process_key_cipher - Perform key cipher initialization. + * @key_tfm: Crypto context for key material, set by this function + * @cipher_name: Name of the cipher + * @key_size: Size of the key in bytes + * + * Returns zero on success. Any crypto_tfm structs allocated here + * should be released by other functions, such as on a superblock put + * event, regardless of whether this function succeeds for fails. + */ +static int +ecryptfs_process_key_cipher(struct crypto_skcipher **key_tfm, + char *cipher_name, size_t *key_size) +{ + char dummy_key[ECRYPTFS_MAX_KEY_BYTES]; + char *full_alg_name = NULL; + int rc; + + *key_tfm = NULL; + if (*key_size > ECRYPTFS_MAX_KEY_BYTES) { + rc = -EINVAL; + printk(KERN_ERR "Requested key size is [%zd] bytes; maximum " + "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES); + goto out; + } + rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name, + "ecb"); + if (rc) + goto out; + *key_tfm = crypto_alloc_skcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC); + if (IS_ERR(*key_tfm)) { + rc = PTR_ERR(*key_tfm); + printk(KERN_ERR "Unable to allocate crypto cipher with name " + "[%s]; rc = [%d]\n", full_alg_name, rc); + goto out; + } + crypto_skcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS); + if (*key_size == 0) + *key_size = crypto_skcipher_max_keysize(*key_tfm); + get_random_bytes(dummy_key, *key_size); + rc = crypto_skcipher_setkey(*key_tfm, dummy_key, *key_size); + if (rc) { + printk(KERN_ERR "Error attempting to set key of size [%zd] for " + "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name, + rc); + rc = -EINVAL; + goto out; + } +out: + kfree(full_alg_name); + return rc; +} + +struct kmem_cache *ecryptfs_key_tfm_cache; +static struct list_head key_tfm_list; +struct mutex key_tfm_list_mutex; + +int __init ecryptfs_init_crypto(void) +{ + mutex_init(&key_tfm_list_mutex); + INIT_LIST_HEAD(&key_tfm_list); + return 0; +} + +/** + * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list + * + * Called only at module unload time + */ +int ecryptfs_destroy_crypto(void) +{ + struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp; + + mutex_lock(&key_tfm_list_mutex); + list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list, + key_tfm_list) { + list_del(&key_tfm->key_tfm_list); + crypto_free_skcipher(key_tfm->key_tfm); + kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm); + } + mutex_unlock(&key_tfm_list_mutex); + return 0; +} + +int +ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name, + size_t key_size) +{ + struct ecryptfs_key_tfm *tmp_tfm; + int rc = 0; + + BUG_ON(!mutex_is_locked(&key_tfm_list_mutex)); + + tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL); + if (key_tfm) + (*key_tfm) = tmp_tfm; + if (!tmp_tfm) { + rc = -ENOMEM; + goto out; + } + mutex_init(&tmp_tfm->key_tfm_mutex); + strncpy(tmp_tfm->cipher_name, cipher_name, + ECRYPTFS_MAX_CIPHER_NAME_SIZE); + tmp_tfm->cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0'; + tmp_tfm->key_size = key_size; + rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm, + tmp_tfm->cipher_name, + &tmp_tfm->key_size); + if (rc) { + printk(KERN_ERR "Error attempting to initialize key TFM " + "cipher with name = [%s]; rc = [%d]\n", + tmp_tfm->cipher_name, rc); + kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm); + if (key_tfm) + (*key_tfm) = NULL; + goto out; + } + list_add(&tmp_tfm->key_tfm_list, &key_tfm_list); +out: + return rc; +} + +/** + * ecryptfs_tfm_exists - Search for existing tfm for cipher_name. + * @cipher_name: the name of the cipher to search for + * @key_tfm: set to corresponding tfm if found + * + * Searches for cached key_tfm matching @cipher_name + * Must be called with &key_tfm_list_mutex held + * Returns 1 if found, with @key_tfm set + * Returns 0 if not found, with @key_tfm set to NULL + */ +int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm) +{ + struct ecryptfs_key_tfm *tmp_key_tfm; + + BUG_ON(!mutex_is_locked(&key_tfm_list_mutex)); + + list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) { + if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) { + if (key_tfm) + (*key_tfm) = tmp_key_tfm; + return 1; + } + } + if (key_tfm) + (*key_tfm) = NULL; + return 0; +} + +/** + * ecryptfs_get_tfm_and_mutex_for_cipher_name + * + * @tfm: set to cached tfm found, or new tfm created + * @tfm_mutex: set to mutex for cached tfm found, or new tfm created + * @cipher_name: the name of the cipher to search for and/or add + * + * Sets pointers to @tfm & @tfm_mutex matching @cipher_name. + * Searches for cached item first, and creates new if not found. + * Returns 0 on success, non-zero if adding new cipher failed + */ +int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_skcipher **tfm, + struct mutex **tfm_mutex, + char *cipher_name) +{ + struct ecryptfs_key_tfm *key_tfm; + int rc = 0; + + (*tfm) = NULL; + (*tfm_mutex) = NULL; + + mutex_lock(&key_tfm_list_mutex); + if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) { + rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0); + if (rc) { + printk(KERN_ERR "Error adding new key_tfm to list; " + "rc = [%d]\n", rc); + goto out; + } + } + (*tfm) = key_tfm->key_tfm; + (*tfm_mutex) = &key_tfm->key_tfm_mutex; +out: + mutex_unlock(&key_tfm_list_mutex); + return rc; +} + +/* 64 characters forming a 6-bit target field */ +static unsigned char *portable_filename_chars = ("-.0123456789ABCD" + "EFGHIJKLMNOPQRST" + "UVWXYZabcdefghij" + "klmnopqrstuvwxyz"); + +/* We could either offset on every reverse map or just pad some 0x00's + * at the front here */ +static const unsigned char filename_rev_map[256] = { + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */ + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */ + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */ + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */ + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */ + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */ + 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */ + 0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */ + 0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */ + 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */ + 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */ + 0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */ + 0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */ + 0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */ + 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */ + 0x3D, 0x3E, 0x3F /* 123 - 255 initialized to 0x00 */ +}; + +/** + * ecryptfs_encode_for_filename + * @dst: Destination location for encoded filename + * @dst_size: Size of the encoded filename in bytes + * @src: Source location for the filename to encode + * @src_size: Size of the source in bytes + */ +static void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size, + unsigned char *src, size_t src_size) +{ + size_t num_blocks; + size_t block_num = 0; + size_t dst_offset = 0; + unsigned char last_block[3]; + + if (src_size == 0) { + (*dst_size) = 0; + goto out; + } + num_blocks = (src_size / 3); + if ((src_size % 3) == 0) { + memcpy(last_block, (&src[src_size - 3]), 3); + } else { + num_blocks++; + last_block[2] = 0x00; + switch (src_size % 3) { + case 1: + last_block[0] = src[src_size - 1]; + last_block[1] = 0x00; + break; + case 2: + last_block[0] = src[src_size - 2]; + last_block[1] = src[src_size - 1]; + } + } + (*dst_size) = (num_blocks * 4); + if (!dst) + goto out; + while (block_num < num_blocks) { + unsigned char *src_block; + unsigned char dst_block[4]; + + if (block_num == (num_blocks - 1)) + src_block = last_block; + else + src_block = &src[block_num * 3]; + dst_block[0] = ((src_block[0] >> 2) & 0x3F); + dst_block[1] = (((src_block[0] << 4) & 0x30) + | ((src_block[1] >> 4) & 0x0F)); + dst_block[2] = (((src_block[1] << 2) & 0x3C) + | ((src_block[2] >> 6) & 0x03)); + dst_block[3] = (src_block[2] & 0x3F); + dst[dst_offset++] = portable_filename_chars[dst_block[0]]; + dst[dst_offset++] = portable_filename_chars[dst_block[1]]; + dst[dst_offset++] = portable_filename_chars[dst_block[2]]; + dst[dst_offset++] = portable_filename_chars[dst_block[3]]; + block_num++; + } +out: + return; +} + +static size_t ecryptfs_max_decoded_size(size_t encoded_size) +{ + /* Not exact; conservatively long. Every block of 4 + * encoded characters decodes into a block of 3 + * decoded characters. This segment of code provides + * the caller with the maximum amount of allocated + * space that @dst will need to point to in a + * subsequent call. */ + return ((encoded_size + 1) * 3) / 4; +} + +/** + * ecryptfs_decode_from_filename + * @dst: If NULL, this function only sets @dst_size and returns. If + * non-NULL, this function decodes the encoded octets in @src + * into the memory that @dst points to. + * @dst_size: Set to the size of the decoded string. + * @src: The encoded set of octets to decode. + * @src_size: The size of the encoded set of octets to decode. + */ +static void +ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size, + const unsigned char *src, size_t src_size) +{ + u8 current_bit_offset = 0; + size_t src_byte_offset = 0; + size_t dst_byte_offset = 0; + + if (!dst) { + (*dst_size) = ecryptfs_max_decoded_size(src_size); + goto out; + } + while (src_byte_offset < src_size) { + unsigned char src_byte = + filename_rev_map[(int)src[src_byte_offset]]; + + switch (current_bit_offset) { + case 0: + dst[dst_byte_offset] = (src_byte << 2); + current_bit_offset = 6; + break; + case 6: + dst[dst_byte_offset++] |= (src_byte >> 4); + dst[dst_byte_offset] = ((src_byte & 0xF) + << 4); + current_bit_offset = 4; + break; + case 4: + dst[dst_byte_offset++] |= (src_byte >> 2); + dst[dst_byte_offset] = (src_byte << 6); + current_bit_offset = 2; + break; + case 2: + dst[dst_byte_offset++] |= (src_byte); + current_bit_offset = 0; + break; + } + src_byte_offset++; + } + (*dst_size) = dst_byte_offset; +out: + return; +} + +/** + * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text + * @crypt_stat: The crypt_stat struct associated with the file anem to encode + * @name: The plaintext name + * @length: The length of the plaintext + * @encoded_name: The encypted name + * + * Encrypts and encodes a filename into something that constitutes a + * valid filename for a filesystem, with printable characters. + * + * We assume that we have a properly initialized crypto context, + * pointed to by crypt_stat->tfm. + * + * Returns zero on success; non-zero on otherwise + */ +int ecryptfs_encrypt_and_encode_filename( + char **encoded_name, + size_t *encoded_name_size, + struct ecryptfs_mount_crypt_stat *mount_crypt_stat, + const char *name, size_t name_size) +{ + size_t encoded_name_no_prefix_size; + int rc = 0; + + (*encoded_name) = NULL; + (*encoded_name_size) = 0; + if (mount_crypt_stat && (mount_crypt_stat->flags + & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) { + struct ecryptfs_filename *filename; + + filename = kzalloc(sizeof(*filename), GFP_KERNEL); + if (!filename) { + rc = -ENOMEM; + goto out; + } + filename->filename = (char *)name; + filename->filename_size = name_size; + rc = ecryptfs_encrypt_filename(filename, mount_crypt_stat); + if (rc) { + printk(KERN_ERR "%s: Error attempting to encrypt " + "filename; rc = [%d]\n", __func__, rc); + kfree(filename); + goto out; + } + ecryptfs_encode_for_filename( + NULL, &encoded_name_no_prefix_size, + filename->encrypted_filename, + filename->encrypted_filename_size); + if (mount_crypt_stat + && (mount_crypt_stat->flags + & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) + (*encoded_name_size) = + (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE + + encoded_name_no_prefix_size); + else + (*encoded_name_size) = + (ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE + + encoded_name_no_prefix_size); + (*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL); + if (!(*encoded_name)) { + rc = -ENOMEM; + kfree(filename->encrypted_filename); + kfree(filename); + goto out; + } + if (mount_crypt_stat + && (mount_crypt_stat->flags + & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) { + memcpy((*encoded_name), + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX, + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE); + ecryptfs_encode_for_filename( + ((*encoded_name) + + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE), + &encoded_name_no_prefix_size, + filename->encrypted_filename, + filename->encrypted_filename_size); + (*encoded_name_size) = + (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE + + encoded_name_no_prefix_size); + (*encoded_name)[(*encoded_name_size)] = '\0'; + } else { + rc = -EOPNOTSUPP; + } + if (rc) { + printk(KERN_ERR "%s: Error attempting to encode " + "encrypted filename; rc = [%d]\n", __func__, + rc); + kfree((*encoded_name)); + (*encoded_name) = NULL; + (*encoded_name_size) = 0; + } + kfree(filename->encrypted_filename); + kfree(filename); + } else { + rc = ecryptfs_copy_filename(encoded_name, + encoded_name_size, + name, name_size); + } +out: + return rc; +} + +static bool is_dot_dotdot(const char *name, size_t name_size) +{ + if (name_size == 1 && name[0] == '.') + return true; + else if (name_size == 2 && name[0] == '.' && name[1] == '.') + return true; + + return false; +} + +/** + * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext + * @plaintext_name: The plaintext name + * @plaintext_name_size: The plaintext name size + * @ecryptfs_dir_dentry: eCryptfs directory dentry + * @name: The filename in cipher text + * @name_size: The cipher text name size + * + * Decrypts and decodes the filename. + * + * Returns zero on error; non-zero otherwise + */ +int ecryptfs_decode_and_decrypt_filename(char **plaintext_name, + size_t *plaintext_name_size, + struct super_block *sb, + const char *name, size_t name_size) +{ + struct ecryptfs_mount_crypt_stat *mount_crypt_stat = + &ecryptfs_superblock_to_private(sb)->mount_crypt_stat; + char *decoded_name; + size_t decoded_name_size; + size_t packet_size; + int rc = 0; + + if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) && + !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)) { + if (is_dot_dotdot(name, name_size)) { + rc = ecryptfs_copy_filename(plaintext_name, + plaintext_name_size, + name, name_size); + goto out; + } + + if (name_size <= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE || + strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX, + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)) { + rc = -EINVAL; + goto out; + } + + name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE; + name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE; + ecryptfs_decode_from_filename(NULL, &decoded_name_size, + name, name_size); + decoded_name = kmalloc(decoded_name_size, GFP_KERNEL); + if (!decoded_name) { + rc = -ENOMEM; + goto out; + } + ecryptfs_decode_from_filename(decoded_name, &decoded_name_size, + name, name_size); + rc = ecryptfs_parse_tag_70_packet(plaintext_name, + plaintext_name_size, + &packet_size, + mount_crypt_stat, + decoded_name, + decoded_name_size); + if (rc) { + ecryptfs_printk(KERN_DEBUG, + "%s: Could not parse tag 70 packet from filename\n", + __func__); + goto out_free; + } + } else { + rc = ecryptfs_copy_filename(plaintext_name, + plaintext_name_size, + name, name_size); + goto out; + } +out_free: + kfree(decoded_name); +out: + return rc; +} + +#define ENC_NAME_MAX_BLOCKLEN_8_OR_16 143 + +int ecryptfs_set_f_namelen(long *namelen, long lower_namelen, + struct ecryptfs_mount_crypt_stat *mount_crypt_stat) +{ + struct crypto_skcipher *tfm; + struct mutex *tfm_mutex; + size_t cipher_blocksize; + int rc; + + if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) { + (*namelen) = lower_namelen; + return 0; + } + + rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex, + mount_crypt_stat->global_default_fn_cipher_name); + if (unlikely(rc)) { + (*namelen) = 0; + return rc; + } + + mutex_lock(tfm_mutex); + cipher_blocksize = crypto_skcipher_blocksize(tfm); + mutex_unlock(tfm_mutex); + + /* Return an exact amount for the common cases */ + if (lower_namelen == NAME_MAX + && (cipher_blocksize == 8 || cipher_blocksize == 16)) { + (*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16; + return 0; + } + + /* Return a safe estimate for the uncommon cases */ + (*namelen) = lower_namelen; + (*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE; + /* Since this is the max decoded size, subtract 1 "decoded block" len */ + (*namelen) = ecryptfs_max_decoded_size(*namelen) - 3; + (*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE; + (*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES; + /* Worst case is that the filename is padded nearly a full block size */ + (*namelen) -= cipher_blocksize - 1; + + if ((*namelen) < 0) + (*namelen) = 0; + + return 0; +} |