// 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 <linux/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; } /** * 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; DECLARE_CRYPTO_WAIT(ecr); int rc = 0; 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); } 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, crypto_req_done, &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); rc = crypto_wait_req(rc, &ecr); 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_local_page(enc_extent_page); rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset, PAGE_SIZE); kunmap_local(enc_extent_virt); 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_local_page(page); rc = ecryptfs_read_lower(page_virt, lower_offset, PAGE_SIZE, ecryptfs_inode); kunmap_local(page_virt); 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 decrypting 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 * * 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(&nop_mnt_idmap, 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; DEFINE_MUTEX(key_tfm_list_mutex); int __init ecryptfs_init_crypto(void) { 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); strscpy(tmp_tfm->cipher_name, cipher_name); 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 * @encoded_name: The encrypted name * @encoded_name_size: Length of the encrypted name * @mount_crypt_stat: The crypt_stat struct associated with the file name to encode * @name: The plaintext name * @name_size: The length of the plaintext 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; } /** * 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 * @sb: Ecryptfs's super_block * @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; }