diff options
Diffstat (limited to 'fs/ext4/crypto.c')
| -rw-r--r-- | fs/ext4/crypto.c | 536 |
1 files changed, 0 insertions, 536 deletions
diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c deleted file mode 100644 index 6a6c27373..000000000 --- a/fs/ext4/crypto.c +++ /dev/null @@ -1,536 +0,0 @@ -/* - * linux/fs/ext4/crypto.c - * - * Copyright (C) 2015, Google, Inc. - * - * This contains encryption functions for ext4 - * - * Written by Michael Halcrow, 2014. - * - * Filename encryption additions - * Uday Savagaonkar, 2014 - * Encryption policy handling additions - * Ildar Muslukhov, 2014 - * - * This has not yet undergone a rigorous security audit. - * - * The usage of AES-XTS should conform to recommendations in NIST - * Special Publication 800-38E and IEEE P1619/D16. - */ - -#include <crypto/skcipher.h> -#include <keys/user-type.h> -#include <keys/encrypted-type.h> -#include <linux/ecryptfs.h> -#include <linux/gfp.h> -#include <linux/kernel.h> -#include <linux/key.h> -#include <linux/list.h> -#include <linux/mempool.h> -#include <linux/module.h> -#include <linux/mutex.h> -#include <linux/random.h> -#include <linux/scatterlist.h> -#include <linux/spinlock_types.h> -#include <linux/namei.h> - -#include "ext4_extents.h" -#include "xattr.h" - -/* Encryption added and removed here! (L: */ - -static unsigned int num_prealloc_crypto_pages = 32; -static unsigned int num_prealloc_crypto_ctxs = 128; - -module_param(num_prealloc_crypto_pages, uint, 0444); -MODULE_PARM_DESC(num_prealloc_crypto_pages, - "Number of crypto pages to preallocate"); -module_param(num_prealloc_crypto_ctxs, uint, 0444); -MODULE_PARM_DESC(num_prealloc_crypto_ctxs, - "Number of crypto contexts to preallocate"); - -static mempool_t *ext4_bounce_page_pool; - -static LIST_HEAD(ext4_free_crypto_ctxs); -static DEFINE_SPINLOCK(ext4_crypto_ctx_lock); - -static struct kmem_cache *ext4_crypto_ctx_cachep; -struct kmem_cache *ext4_crypt_info_cachep; - -/** - * ext4_release_crypto_ctx() - Releases an encryption context - * @ctx: The encryption context to release. - * - * If the encryption context was allocated from the pre-allocated pool, returns - * it to that pool. Else, frees it. - * - * If there's a bounce page in the context, this frees that. - */ -void ext4_release_crypto_ctx(struct ext4_crypto_ctx *ctx) -{ - unsigned long flags; - - if (ctx->flags & EXT4_WRITE_PATH_FL && ctx->w.bounce_page) - mempool_free(ctx->w.bounce_page, ext4_bounce_page_pool); - ctx->w.bounce_page = NULL; - ctx->w.control_page = NULL; - if (ctx->flags & EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL) { - kmem_cache_free(ext4_crypto_ctx_cachep, ctx); - } else { - spin_lock_irqsave(&ext4_crypto_ctx_lock, flags); - list_add(&ctx->free_list, &ext4_free_crypto_ctxs); - spin_unlock_irqrestore(&ext4_crypto_ctx_lock, flags); - } -} - -/** - * ext4_get_crypto_ctx() - Gets an encryption context - * @inode: The inode for which we are doing the crypto - * - * Allocates and initializes an encryption context. - * - * Return: An allocated and initialized encryption context on success; error - * value or NULL otherwise. - */ -struct ext4_crypto_ctx *ext4_get_crypto_ctx(struct inode *inode, - gfp_t gfp_flags) -{ - struct ext4_crypto_ctx *ctx = NULL; - int res = 0; - unsigned long flags; - struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info; - - if (ci == NULL) - return ERR_PTR(-ENOKEY); - - /* - * We first try getting the ctx from a free list because in - * the common case the ctx will have an allocated and - * initialized crypto tfm, so it's probably a worthwhile - * optimization. For the bounce page, we first try getting it - * from the kernel allocator because that's just about as fast - * as getting it from a list and because a cache of free pages - * should generally be a "last resort" option for a filesystem - * to be able to do its job. - */ - spin_lock_irqsave(&ext4_crypto_ctx_lock, flags); - ctx = list_first_entry_or_null(&ext4_free_crypto_ctxs, - struct ext4_crypto_ctx, free_list); - if (ctx) - list_del(&ctx->free_list); - spin_unlock_irqrestore(&ext4_crypto_ctx_lock, flags); - if (!ctx) { - ctx = kmem_cache_zalloc(ext4_crypto_ctx_cachep, gfp_flags); - if (!ctx) { - res = -ENOMEM; - goto out; - } - ctx->flags |= EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL; - } else { - ctx->flags &= ~EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL; - } - ctx->flags &= ~EXT4_WRITE_PATH_FL; - -out: - if (res) { - if (!IS_ERR_OR_NULL(ctx)) - ext4_release_crypto_ctx(ctx); - ctx = ERR_PTR(res); - } - return ctx; -} - -struct workqueue_struct *ext4_read_workqueue; -static DEFINE_MUTEX(crypto_init); - -/** - * ext4_exit_crypto() - Shutdown the ext4 encryption system - */ -void ext4_exit_crypto(void) -{ - struct ext4_crypto_ctx *pos, *n; - - list_for_each_entry_safe(pos, n, &ext4_free_crypto_ctxs, free_list) - kmem_cache_free(ext4_crypto_ctx_cachep, pos); - INIT_LIST_HEAD(&ext4_free_crypto_ctxs); - if (ext4_bounce_page_pool) - mempool_destroy(ext4_bounce_page_pool); - ext4_bounce_page_pool = NULL; - if (ext4_read_workqueue) - destroy_workqueue(ext4_read_workqueue); - ext4_read_workqueue = NULL; - if (ext4_crypto_ctx_cachep) - kmem_cache_destroy(ext4_crypto_ctx_cachep); - ext4_crypto_ctx_cachep = NULL; - if (ext4_crypt_info_cachep) - kmem_cache_destroy(ext4_crypt_info_cachep); - ext4_crypt_info_cachep = NULL; -} - -/** - * ext4_init_crypto() - Set up for ext4 encryption. - * - * We only call this when we start accessing encrypted files, since it - * results in memory getting allocated that wouldn't otherwise be used. - * - * Return: Zero on success, non-zero otherwise. - */ -int ext4_init_crypto(void) -{ - int i, res = -ENOMEM; - - mutex_lock(&crypto_init); - if (ext4_read_workqueue) - goto already_initialized; - ext4_read_workqueue = alloc_workqueue("ext4_crypto", WQ_HIGHPRI, 0); - if (!ext4_read_workqueue) - goto fail; - - ext4_crypto_ctx_cachep = KMEM_CACHE(ext4_crypto_ctx, - SLAB_RECLAIM_ACCOUNT); - if (!ext4_crypto_ctx_cachep) - goto fail; - - ext4_crypt_info_cachep = KMEM_CACHE(ext4_crypt_info, - SLAB_RECLAIM_ACCOUNT); - if (!ext4_crypt_info_cachep) - goto fail; - - for (i = 0; i < num_prealloc_crypto_ctxs; i++) { - struct ext4_crypto_ctx *ctx; - - ctx = kmem_cache_zalloc(ext4_crypto_ctx_cachep, GFP_NOFS); - if (!ctx) { - res = -ENOMEM; - goto fail; - } - list_add(&ctx->free_list, &ext4_free_crypto_ctxs); - } - - ext4_bounce_page_pool = - mempool_create_page_pool(num_prealloc_crypto_pages, 0); - if (!ext4_bounce_page_pool) { - res = -ENOMEM; - goto fail; - } -already_initialized: - mutex_unlock(&crypto_init); - return 0; -fail: - ext4_exit_crypto(); - mutex_unlock(&crypto_init); - return res; -} - -void ext4_restore_control_page(struct page *data_page) -{ - struct ext4_crypto_ctx *ctx = - (struct ext4_crypto_ctx *)page_private(data_page); - - set_page_private(data_page, (unsigned long)NULL); - ClearPagePrivate(data_page); - unlock_page(data_page); - ext4_release_crypto_ctx(ctx); -} - -/** - * ext4_crypt_complete() - The completion callback for page encryption - * @req: The asynchronous encryption request context - * @res: The result of the encryption operation - */ -static void ext4_crypt_complete(struct crypto_async_request *req, int res) -{ - struct ext4_completion_result *ecr = req->data; - - if (res == -EINPROGRESS) - return; - ecr->res = res; - complete(&ecr->completion); -} - -typedef enum { - EXT4_DECRYPT = 0, - EXT4_ENCRYPT, -} ext4_direction_t; - -static int ext4_page_crypto(struct inode *inode, - ext4_direction_t rw, - pgoff_t index, - struct page *src_page, - struct page *dest_page, - gfp_t gfp_flags) - -{ - u8 xts_tweak[EXT4_XTS_TWEAK_SIZE]; - struct skcipher_request *req = NULL; - DECLARE_EXT4_COMPLETION_RESULT(ecr); - struct scatterlist dst, src; - struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info; - struct crypto_skcipher *tfm = ci->ci_ctfm; - int res = 0; - - req = skcipher_request_alloc(tfm, gfp_flags); - if (!req) { - printk_ratelimited(KERN_ERR - "%s: crypto_request_alloc() failed\n", - __func__); - return -ENOMEM; - } - skcipher_request_set_callback( - req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, - ext4_crypt_complete, &ecr); - - BUILD_BUG_ON(EXT4_XTS_TWEAK_SIZE < sizeof(index)); - memcpy(xts_tweak, &index, sizeof(index)); - memset(&xts_tweak[sizeof(index)], 0, - EXT4_XTS_TWEAK_SIZE - sizeof(index)); - - sg_init_table(&dst, 1); - sg_set_page(&dst, dest_page, PAGE_SIZE, 0); - sg_init_table(&src, 1); - sg_set_page(&src, src_page, PAGE_SIZE, 0); - skcipher_request_set_crypt(req, &src, &dst, PAGE_SIZE, - xts_tweak); - if (rw == EXT4_DECRYPT) - res = crypto_skcipher_decrypt(req); - else - res = crypto_skcipher_encrypt(req); - if (res == -EINPROGRESS || res == -EBUSY) { - wait_for_completion(&ecr.completion); - res = ecr.res; - } - skcipher_request_free(req); - if (res) { - printk_ratelimited( - KERN_ERR - "%s: crypto_skcipher_encrypt() returned %d\n", - __func__, res); - return res; - } - return 0; -} - -static struct page *alloc_bounce_page(struct ext4_crypto_ctx *ctx, - gfp_t gfp_flags) -{ - ctx->w.bounce_page = mempool_alloc(ext4_bounce_page_pool, gfp_flags); - if (ctx->w.bounce_page == NULL) - return ERR_PTR(-ENOMEM); - ctx->flags |= EXT4_WRITE_PATH_FL; - return ctx->w.bounce_page; -} - -/** - * ext4_encrypt() - Encrypts a page - * @inode: The inode for which the encryption should take place - * @plaintext_page: The page to encrypt. Must be locked. - * - * Allocates a ciphertext page and encrypts plaintext_page into it using the ctx - * encryption context. - * - * Called on the page write path. The caller must call - * ext4_restore_control_page() on the returned ciphertext page to - * release the bounce buffer and the encryption context. - * - * Return: An allocated page with the encrypted content on success. Else, an - * error value or NULL. - */ -struct page *ext4_encrypt(struct inode *inode, - struct page *plaintext_page, - gfp_t gfp_flags) -{ - struct ext4_crypto_ctx *ctx; - struct page *ciphertext_page = NULL; - int err; - - BUG_ON(!PageLocked(plaintext_page)); - - ctx = ext4_get_crypto_ctx(inode, gfp_flags); - if (IS_ERR(ctx)) - return (struct page *) ctx; - - /* The encryption operation will require a bounce page. */ - ciphertext_page = alloc_bounce_page(ctx, gfp_flags); - if (IS_ERR(ciphertext_page)) - goto errout; - ctx->w.control_page = plaintext_page; - err = ext4_page_crypto(inode, EXT4_ENCRYPT, plaintext_page->index, - plaintext_page, ciphertext_page, gfp_flags); - if (err) { - ciphertext_page = ERR_PTR(err); - errout: - ext4_release_crypto_ctx(ctx); - return ciphertext_page; - } - SetPagePrivate(ciphertext_page); - set_page_private(ciphertext_page, (unsigned long)ctx); - lock_page(ciphertext_page); - return ciphertext_page; -} - -/** - * ext4_decrypt() - Decrypts a page in-place - * @ctx: The encryption context. - * @page: The page to decrypt. Must be locked. - * - * Decrypts page in-place using the ctx encryption context. - * - * Called from the read completion callback. - * - * Return: Zero on success, non-zero otherwise. - */ -int ext4_decrypt(struct page *page) -{ - BUG_ON(!PageLocked(page)); - - return ext4_page_crypto(page->mapping->host, EXT4_DECRYPT, - page->index, page, page, GFP_NOFS); -} - -int ext4_encrypted_zeroout(struct inode *inode, ext4_lblk_t lblk, - ext4_fsblk_t pblk, ext4_lblk_t len) -{ - struct ext4_crypto_ctx *ctx; - struct page *ciphertext_page = NULL; - struct bio *bio; - int ret, err = 0; - -#if 0 - ext4_msg(inode->i_sb, KERN_CRIT, - "ext4_encrypted_zeroout ino %lu lblk %u len %u", - (unsigned long) inode->i_ino, lblk, len); -#endif - - BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE); - - ctx = ext4_get_crypto_ctx(inode, GFP_NOFS); - if (IS_ERR(ctx)) - return PTR_ERR(ctx); - - ciphertext_page = alloc_bounce_page(ctx, GFP_NOWAIT); - if (IS_ERR(ciphertext_page)) { - err = PTR_ERR(ciphertext_page); - goto errout; - } - - while (len--) { - err = ext4_page_crypto(inode, EXT4_ENCRYPT, lblk, - ZERO_PAGE(0), ciphertext_page, - GFP_NOFS); - if (err) - goto errout; - - bio = bio_alloc(GFP_NOWAIT, 1); - if (!bio) { - err = -ENOMEM; - goto errout; - } - bio->bi_bdev = inode->i_sb->s_bdev; - bio->bi_iter.bi_sector = - pblk << (inode->i_sb->s_blocksize_bits - 9); - ret = bio_add_page(bio, ciphertext_page, - inode->i_sb->s_blocksize, 0); - if (ret != inode->i_sb->s_blocksize) { - /* should never happen! */ - ext4_msg(inode->i_sb, KERN_ERR, - "bio_add_page failed: %d", ret); - WARN_ON(1); - bio_put(bio); - err = -EIO; - goto errout; - } - err = submit_bio_wait(WRITE, bio); - if ((err == 0) && bio->bi_error) - err = -EIO; - bio_put(bio); - if (err) - goto errout; - lblk++; pblk++; - } - err = 0; -errout: - ext4_release_crypto_ctx(ctx); - return err; -} - -bool ext4_valid_contents_enc_mode(uint32_t mode) -{ - return (mode == EXT4_ENCRYPTION_MODE_AES_256_XTS); -} - -/** - * ext4_validate_encryption_key_size() - Validate the encryption key size - * @mode: The key mode. - * @size: The key size to validate. - * - * Return: The validated key size for @mode. Zero if invalid. - */ -uint32_t ext4_validate_encryption_key_size(uint32_t mode, uint32_t size) -{ - if (size == ext4_encryption_key_size(mode)) - return size; - return 0; -} - -/* - * Validate dentries for encrypted directories to make sure we aren't - * potentially caching stale data after a key has been added or - * removed. - */ -static int ext4_d_revalidate(struct dentry *dentry, unsigned int flags) -{ - struct dentry *dir; - struct ext4_crypt_info *ci; - int dir_has_key, cached_with_key; - - if (flags & LOOKUP_RCU) - return -ECHILD; - - dir = dget_parent(dentry); - if (!ext4_encrypted_inode(d_inode(dir))) { - dput(dir); - return 0; - } - ci = EXT4_I(d_inode(dir))->i_crypt_info; - if (ci && ci->ci_keyring_key && - (ci->ci_keyring_key->flags & ((1 << KEY_FLAG_INVALIDATED) | - (1 << KEY_FLAG_REVOKED) | - (1 << KEY_FLAG_DEAD)))) - ci = NULL; - - /* this should eventually be an flag in d_flags */ - cached_with_key = dentry->d_fsdata != NULL; - dir_has_key = (ci != NULL); - dput(dir); - - /* - * If the dentry was cached without the key, and it is a - * negative dentry, it might be a valid name. We can't check - * if the key has since been made available due to locking - * reasons, so we fail the validation so ext4_lookup() can do - * this check. - * - * We also fail the validation if the dentry was created with - * the key present, but we no longer have the key, or vice versa. - */ - if ((!cached_with_key && d_is_negative(dentry)) || - (!cached_with_key && dir_has_key) || - (cached_with_key && !dir_has_key)) { -#if 0 /* Revalidation debug */ - char buf[80]; - char *cp = simple_dname(dentry, buf, sizeof(buf)); - - if (IS_ERR(cp)) - cp = (char *) "???"; - pr_err("revalidate: %s %p %d %d %d\n", cp, dentry->d_fsdata, - cached_with_key, d_is_negative(dentry), - dir_has_key); -#endif - return 0; - } - return 1; -} - -const struct dentry_operations ext4_encrypted_d_ops = { - .d_revalidate = ext4_d_revalidate, -}; |