diff options
Diffstat (limited to 'fs/crypto/inline_crypt.c')
| -rw-r--r-- | fs/crypto/inline_crypt.c | 517 |
1 files changed, 0 insertions, 517 deletions
diff --git a/fs/crypto/inline_crypt.c b/fs/crypto/inline_crypt.c deleted file mode 100644 index c0852b920dbc..000000000000 --- a/fs/crypto/inline_crypt.c +++ /dev/null @@ -1,517 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -/* - * Inline encryption support for fscrypt - * - * Copyright 2019 Google LLC - */ - -/* - * With "inline encryption", the block layer handles the decryption/encryption - * as part of the bio, instead of the filesystem doing the crypto itself via - * crypto API. See Documentation/block/inline-encryption.rst. fscrypt still - * provides the key and IV to use. - */ - -#include <linux/blk-crypto.h> -#include <linux/blkdev.h> -#include <linux/buffer_head.h> -#include <linux/export.h> -#include <linux/sched/mm.h> -#include <linux/slab.h> -#include <linux/uio.h> - -#include "fscrypt_private.h" - -static struct block_device **fscrypt_get_devices(struct super_block *sb, - unsigned int *num_devs) -{ - struct block_device **devs; - - if (sb->s_cop->get_devices) { - devs = sb->s_cop->get_devices(sb, num_devs); - if (devs) - return devs; - } - devs = kmalloc_obj(*devs); - if (!devs) - return ERR_PTR(-ENOMEM); - devs[0] = sb->s_bdev; - *num_devs = 1; - return devs; -} - -static unsigned int fscrypt_get_dun_bytes(const struct fscrypt_inode_info *ci) -{ - const struct super_block *sb = ci->ci_inode->i_sb; - unsigned int flags = fscrypt_policy_flags(&ci->ci_policy); - int dun_bits; - - if (flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) - return offsetofend(union fscrypt_iv, nonce); - - if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) - return sizeof(__le64); - - if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) - return sizeof(__le32); - - /* Default case: IVs are just the file data unit index */ - dun_bits = fscrypt_max_file_dun_bits(sb, ci->ci_data_unit_bits); - return DIV_ROUND_UP(dun_bits, 8); -} - -/* - * Log a message when starting to use blk-crypto (native) or blk-crypto-fallback - * for an encryption mode for the first time. This is the blk-crypto - * counterpart to the message logged when starting to use the crypto API for the - * first time. A limitation is that these messages don't convey which specific - * filesystems or files are using each implementation. However, *usually* - * systems use just one implementation per mode, which makes these messages - * helpful for debugging problems where the "wrong" implementation is used. - */ -static void fscrypt_log_blk_crypto_impl(struct fscrypt_mode *mode, - struct block_device **devs, - unsigned int num_devs, - const struct blk_crypto_config *cfg) -{ - unsigned int i; - - for (i = 0; i < num_devs; i++) { - if (!IS_ENABLED(CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK) || - blk_crypto_config_supported_natively(devs[i], cfg)) { - if (!xchg(&mode->logged_blk_crypto_native, 1)) - pr_info("fscrypt: %s using blk-crypto (native)\n", - mode->friendly_name); - } else if (!xchg(&mode->logged_blk_crypto_fallback, 1)) { - pr_info("fscrypt: %s using blk-crypto-fallback\n", - mode->friendly_name); - } - } -} - -/* Enable inline encryption for this file if supported. */ -int fscrypt_select_encryption_impl(struct fscrypt_inode_info *ci, - bool is_hw_wrapped_key) -{ - const struct inode *inode = ci->ci_inode; - struct super_block *sb = inode->i_sb; - struct blk_crypto_config crypto_cfg; - struct block_device **devs; - unsigned int num_devs; - unsigned int i; - - /* The file must need contents encryption, not filenames encryption */ - if (!S_ISREG(inode->i_mode)) - return 0; - - /* The crypto mode must have a blk-crypto counterpart */ - if (ci->ci_mode->blk_crypto_mode == BLK_ENCRYPTION_MODE_INVALID) - return 0; - - /* The filesystem must be mounted with -o inlinecrypt */ - if (!(sb->s_flags & SB_INLINECRYPT)) - return 0; - - /* - * When a page contains multiple logically contiguous filesystem blocks, - * some filesystem code only calls fscrypt_mergeable_bio() for the first - * block in the page. This is fine for most of fscrypt's IV generation - * strategies, where contiguous blocks imply contiguous IVs. But it - * doesn't work with IV_INO_LBLK_32. For now, simply exclude - * IV_INO_LBLK_32 with blocksize != PAGE_SIZE from inline encryption. - */ - if ((fscrypt_policy_flags(&ci->ci_policy) & - FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) && - sb->s_blocksize != PAGE_SIZE) - return 0; - - /* - * On all the filesystem's block devices, blk-crypto must support the - * crypto configuration that the file would use. - */ - crypto_cfg.crypto_mode = ci->ci_mode->blk_crypto_mode; - crypto_cfg.data_unit_size = 1U << ci->ci_data_unit_bits; - crypto_cfg.dun_bytes = fscrypt_get_dun_bytes(ci); - crypto_cfg.key_type = is_hw_wrapped_key ? - BLK_CRYPTO_KEY_TYPE_HW_WRAPPED : BLK_CRYPTO_KEY_TYPE_RAW; - - devs = fscrypt_get_devices(sb, &num_devs); - if (IS_ERR(devs)) - return PTR_ERR(devs); - - for (i = 0; i < num_devs; i++) { - if (!blk_crypto_config_supported(devs[i], &crypto_cfg)) - goto out_free_devs; - } - - fscrypt_log_blk_crypto_impl(ci->ci_mode, devs, num_devs, &crypto_cfg); - - ci->ci_inlinecrypt = true; -out_free_devs: - kfree(devs); - - return 0; -} - -int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key, - const u8 *key_bytes, size_t key_size, - bool is_hw_wrapped, - const struct fscrypt_inode_info *ci) -{ - const struct inode *inode = ci->ci_inode; - struct super_block *sb = inode->i_sb; - enum blk_crypto_mode_num crypto_mode = ci->ci_mode->blk_crypto_mode; - enum blk_crypto_key_type key_type = is_hw_wrapped ? - BLK_CRYPTO_KEY_TYPE_HW_WRAPPED : BLK_CRYPTO_KEY_TYPE_RAW; - struct blk_crypto_key *blk_key; - struct block_device **devs; - unsigned int num_devs; - unsigned int i; - int err; - - blk_key = kmalloc_obj(*blk_key); - if (!blk_key) - return -ENOMEM; - - err = blk_crypto_init_key(blk_key, key_bytes, key_size, key_type, - crypto_mode, fscrypt_get_dun_bytes(ci), - 1U << ci->ci_data_unit_bits); - if (err) { - fscrypt_err(inode, "error %d initializing blk-crypto key", err); - goto fail; - } - - /* Start using blk-crypto on all the filesystem's block devices. */ - devs = fscrypt_get_devices(sb, &num_devs); - if (IS_ERR(devs)) { - err = PTR_ERR(devs); - goto fail; - } - for (i = 0; i < num_devs; i++) { - err = blk_crypto_start_using_key(devs[i], blk_key); - if (err) - break; - } - kfree(devs); - if (err) { - fscrypt_err(inode, "error %d starting to use blk-crypto", err); - goto fail; - } - - /* - * Pairs with the smp_load_acquire() in fscrypt_is_key_prepared(). - * I.e., here we publish ->blk_key with a RELEASE barrier so that - * concurrent tasks can ACQUIRE it. Note that this concurrency is only - * possible for per-mode keys, not for per-file keys. - */ - smp_store_release(&prep_key->blk_key, blk_key); - return 0; - -fail: - kfree_sensitive(blk_key); - return err; -} - -void fscrypt_destroy_inline_crypt_key(struct super_block *sb, - struct fscrypt_prepared_key *prep_key) -{ - struct blk_crypto_key *blk_key = prep_key->blk_key; - struct block_device **devs; - unsigned int num_devs; - unsigned int i; - - if (!blk_key) - return; - - /* Evict the key from all the filesystem's block devices. */ - devs = fscrypt_get_devices(sb, &num_devs); - if (!IS_ERR(devs)) { - for (i = 0; i < num_devs; i++) - blk_crypto_evict_key(devs[i], blk_key); - kfree(devs); - } - kfree_sensitive(blk_key); -} - -/* - * Ask the inline encryption hardware to derive the software secret from a - * hardware-wrapped key. Returns -EOPNOTSUPP if hardware-wrapped keys aren't - * supported on this filesystem or hardware. - */ -int fscrypt_derive_sw_secret(struct super_block *sb, - const u8 *wrapped_key, size_t wrapped_key_size, - u8 sw_secret[BLK_CRYPTO_SW_SECRET_SIZE]) -{ - int err; - - /* The filesystem must be mounted with -o inlinecrypt. */ - if (!(sb->s_flags & SB_INLINECRYPT)) { - fscrypt_warn(NULL, - "%s: filesystem not mounted with inlinecrypt\n", - sb->s_id); - return -EOPNOTSUPP; - } - - err = blk_crypto_derive_sw_secret(sb->s_bdev, wrapped_key, - wrapped_key_size, sw_secret); - if (err == -EOPNOTSUPP) - fscrypt_warn(NULL, - "%s: block device doesn't support hardware-wrapped keys\n", - sb->s_id); - return err; -} - -bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode) -{ - return fscrypt_get_inode_info_raw(inode)->ci_inlinecrypt; -} -EXPORT_SYMBOL_GPL(__fscrypt_inode_uses_inline_crypto); - -static void fscrypt_generate_dun(const struct fscrypt_inode_info *ci, - u64 lblk_num, - u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE]) -{ - u64 index = lblk_num << ci->ci_data_units_per_block_bits; - union fscrypt_iv iv; - int i; - - fscrypt_generate_iv(&iv, index, ci); - - BUILD_BUG_ON(FSCRYPT_MAX_IV_SIZE > BLK_CRYPTO_MAX_IV_SIZE); - memset(dun, 0, BLK_CRYPTO_MAX_IV_SIZE); - for (i = 0; i < ci->ci_mode->ivsize/sizeof(dun[0]); i++) - dun[i] = le64_to_cpu(iv.dun[i]); -} - -/** - * fscrypt_set_bio_crypt_ctx() - prepare a file contents bio for inline crypto - * @bio: a bio which will eventually be submitted to the file - * @inode: the file's inode - * @first_lblk: the first file logical block number in the I/O - * @gfp_mask: memory allocation flags - these must be a waiting mask so that - * bio_crypt_set_ctx can't fail. - * - * If the contents of the file should be encrypted (or decrypted) with inline - * encryption, then assign the appropriate encryption context to the bio. - * - * Normally the bio should be newly allocated (i.e. no pages added yet), as - * otherwise fscrypt_mergeable_bio() won't work as intended. - * - * The encryption context will be freed automatically when the bio is freed. - */ -void fscrypt_set_bio_crypt_ctx(struct bio *bio, const struct inode *inode, - u64 first_lblk, gfp_t gfp_mask) -{ - const struct fscrypt_inode_info *ci; - u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE]; - - if (!fscrypt_inode_uses_inline_crypto(inode)) - return; - ci = fscrypt_get_inode_info_raw(inode); - - fscrypt_generate_dun(ci, first_lblk, dun); - bio_crypt_set_ctx(bio, ci->ci_enc_key.blk_key, dun, gfp_mask); -} -EXPORT_SYMBOL_GPL(fscrypt_set_bio_crypt_ctx); - -/* Extract the inode and logical block number from a buffer_head. */ -static bool bh_get_inode_and_lblk_num(const struct buffer_head *bh, - const struct inode **inode_ret, - u64 *lblk_num_ret) -{ - struct folio *folio = bh->b_folio; - const struct address_space *mapping; - const struct inode *inode; - - /* - * The ext4 journal (jbd2) can submit a buffer_head it directly created - * for a non-pagecache page. fscrypt doesn't care about these. - */ - mapping = folio_mapping(folio); - if (!mapping) - return false; - inode = mapping->host; - - *inode_ret = inode; - *lblk_num_ret = (folio_pos(folio) + bh_offset(bh)) >> inode->i_blkbits; - return true; -} - -/** - * fscrypt_set_bio_crypt_ctx_bh() - prepare a file contents bio for inline - * crypto - * @bio: a bio which will eventually be submitted to the file - * @first_bh: the first buffer_head for which I/O will be submitted - * @gfp_mask: memory allocation flags - * - * Same as fscrypt_set_bio_crypt_ctx(), except this takes a buffer_head instead - * of an inode and block number directly. - */ -void fscrypt_set_bio_crypt_ctx_bh(struct bio *bio, - const struct buffer_head *first_bh, - gfp_t gfp_mask) -{ - const struct inode *inode; - u64 first_lblk; - - if (bh_get_inode_and_lblk_num(first_bh, &inode, &first_lblk)) - fscrypt_set_bio_crypt_ctx(bio, inode, first_lblk, gfp_mask); -} -EXPORT_SYMBOL_GPL(fscrypt_set_bio_crypt_ctx_bh); - -/** - * fscrypt_mergeable_bio() - test whether data can be added to a bio - * @bio: the bio being built up - * @inode: the inode for the next part of the I/O - * @next_lblk: the next file logical block number in the I/O - * - * When building a bio which may contain data which should undergo inline - * encryption (or decryption) via fscrypt, filesystems should call this function - * to ensure that the resulting bio contains only contiguous data unit numbers. - * This will return false if the next part of the I/O cannot be merged with the - * bio because either the encryption key would be different or the encryption - * data unit numbers would be discontiguous. - * - * fscrypt_set_bio_crypt_ctx() must have already been called on the bio. - * - * This function isn't required in cases where crypto-mergeability is ensured in - * another way, such as I/O targeting only a single file (and thus a single key) - * combined with fscrypt_limit_io_blocks() to ensure DUN contiguity. - * - * Return: true iff the I/O is mergeable - */ -bool fscrypt_mergeable_bio(struct bio *bio, const struct inode *inode, - u64 next_lblk) -{ - const struct bio_crypt_ctx *bc = bio->bi_crypt_context; - const struct fscrypt_inode_info *ci; - u64 next_dun[BLK_CRYPTO_DUN_ARRAY_SIZE]; - - if (!!bc != fscrypt_inode_uses_inline_crypto(inode)) - return false; - if (!bc) - return true; - ci = fscrypt_get_inode_info_raw(inode); - - /* - * Comparing the key pointers is good enough, as all I/O for each key - * uses the same pointer. I.e., there's currently no need to support - * merging requests where the keys are the same but the pointers differ. - */ - if (bc->bc_key != ci->ci_enc_key.blk_key) - return false; - - fscrypt_generate_dun(ci, next_lblk, next_dun); - return bio_crypt_dun_is_contiguous(bc, bio->bi_iter.bi_size, next_dun); -} -EXPORT_SYMBOL_GPL(fscrypt_mergeable_bio); - -/** - * fscrypt_mergeable_bio_bh() - test whether data can be added to a bio - * @bio: the bio being built up - * @next_bh: the next buffer_head for which I/O will be submitted - * - * Same as fscrypt_mergeable_bio(), except this takes a buffer_head instead of - * an inode and block number directly. - * - * Return: true iff the I/O is mergeable - */ -bool fscrypt_mergeable_bio_bh(struct bio *bio, - const struct buffer_head *next_bh) -{ - const struct inode *inode; - u64 next_lblk; - - if (!bh_get_inode_and_lblk_num(next_bh, &inode, &next_lblk)) - return !bio->bi_crypt_context; - - return fscrypt_mergeable_bio(bio, inode, next_lblk); -} -EXPORT_SYMBOL_GPL(fscrypt_mergeable_bio_bh); - -/** - * fscrypt_dio_supported() - check whether DIO (direct I/O) is supported on an - * inode, as far as encryption is concerned - * @inode: the inode in question - * - * Return: %true if there are no encryption constraints that prevent DIO from - * being supported; %false if DIO is unsupported. (Note that in the - * %true case, the filesystem might have other, non-encryption-related - * constraints that prevent DIO from actually being supported. Also, on - * encrypted files the filesystem is still responsible for only allowing - * DIO when requests are filesystem-block-aligned.) - */ -bool fscrypt_dio_supported(struct inode *inode) -{ - int err; - - /* If the file is unencrypted, no veto from us. */ - if (!fscrypt_needs_contents_encryption(inode)) - return true; - - /* - * We only support DIO with inline crypto, not fs-layer crypto. - * - * To determine whether the inode is using inline crypto, we have to set - * up the key if it wasn't already done. This is because in the current - * design of fscrypt, the decision of whether to use inline crypto or - * not isn't made until the inode's encryption key is being set up. In - * the DIO read/write case, the key will always be set up already, since - * the file will be open. But in the case of statx(), the key might not - * be set up yet, as the file might not have been opened yet. - */ - err = fscrypt_require_key(inode); - if (err) { - /* - * Key unavailable or couldn't be set up. This edge case isn't - * worth worrying about; just report that DIO is unsupported. - */ - return false; - } - return fscrypt_inode_uses_inline_crypto(inode); -} -EXPORT_SYMBOL_GPL(fscrypt_dio_supported); - -/** - * fscrypt_limit_io_blocks() - limit I/O blocks to avoid discontiguous DUNs - * @inode: the file on which I/O is being done - * @lblk: the block at which the I/O is being started from - * @nr_blocks: the number of blocks we want to submit starting at @lblk - * - * Determine the limit to the number of blocks that can be submitted in a bio - * targeting @lblk without causing a data unit number (DUN) discontiguity. - * - * This is normally just @nr_blocks, as normally the DUNs just increment along - * with the logical blocks. (Or the file is not encrypted.) - * - * In rare cases, fscrypt can be using an IV generation method that allows the - * DUN to wrap around within logically contiguous blocks, and that wraparound - * will occur. If this happens, a value less than @nr_blocks will be returned - * so that the wraparound doesn't occur in the middle of a bio, which would - * cause encryption/decryption to produce wrong results. - * - * Return: the actual number of blocks that can be submitted - */ -u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk, u64 nr_blocks) -{ - const struct fscrypt_inode_info *ci; - u32 dun; - - if (!fscrypt_inode_uses_inline_crypto(inode)) - return nr_blocks; - - if (nr_blocks <= 1) - return nr_blocks; - - ci = fscrypt_get_inode_info_raw(inode); - if (!(fscrypt_policy_flags(&ci->ci_policy) & - FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) - return nr_blocks; - - /* With IV_INO_LBLK_32, the DUN can wrap around from U32_MAX to 0. */ - - dun = ci->ci_hashed_ino + lblk; - - return min_t(u64, nr_blocks, (u64)U32_MAX + 1 - dun); -} -EXPORT_SYMBOL_GPL(fscrypt_limit_io_blocks); |