15fee3609SSatya Tangirala // SPDX-License-Identifier: GPL-2.0 25fee3609SSatya Tangirala /* 35fee3609SSatya Tangirala * Inline encryption support for fscrypt 45fee3609SSatya Tangirala * 55fee3609SSatya Tangirala * Copyright 2019 Google LLC 65fee3609SSatya Tangirala */ 75fee3609SSatya Tangirala 85fee3609SSatya Tangirala /* 95fee3609SSatya Tangirala * With "inline encryption", the block layer handles the decryption/encryption 105fee3609SSatya Tangirala * as part of the bio, instead of the filesystem doing the crypto itself via 115fee3609SSatya Tangirala * crypto API. See Documentation/block/inline-encryption.rst. fscrypt still 125fee3609SSatya Tangirala * provides the key and IV to use. 135fee3609SSatya Tangirala */ 145fee3609SSatya Tangirala 155fee3609SSatya Tangirala #include <linux/blk-crypto.h> 165fee3609SSatya Tangirala #include <linux/blkdev.h> 175fee3609SSatya Tangirala #include <linux/buffer_head.h> 185fee3609SSatya Tangirala #include <linux/sched/mm.h> 19453431a5SWaiman Long #include <linux/slab.h> 20*c6c89783SEric Biggers #include <linux/uio.h> 215fee3609SSatya Tangirala 225fee3609SSatya Tangirala #include "fscrypt_private.h" 235fee3609SSatya Tangirala 245fee3609SSatya Tangirala struct fscrypt_blk_crypto_key { 255fee3609SSatya Tangirala struct blk_crypto_key base; 265fee3609SSatya Tangirala int num_devs; 275fee3609SSatya Tangirala struct request_queue *devs[]; 285fee3609SSatya Tangirala }; 295fee3609SSatya Tangirala 305fee3609SSatya Tangirala static int fscrypt_get_num_devices(struct super_block *sb) 315fee3609SSatya Tangirala { 325fee3609SSatya Tangirala if (sb->s_cop->get_num_devices) 335fee3609SSatya Tangirala return sb->s_cop->get_num_devices(sb); 345fee3609SSatya Tangirala return 1; 355fee3609SSatya Tangirala } 365fee3609SSatya Tangirala 375fee3609SSatya Tangirala static void fscrypt_get_devices(struct super_block *sb, int num_devs, 385fee3609SSatya Tangirala struct request_queue **devs) 395fee3609SSatya Tangirala { 405fee3609SSatya Tangirala if (num_devs == 1) 415fee3609SSatya Tangirala devs[0] = bdev_get_queue(sb->s_bdev); 425fee3609SSatya Tangirala else 435fee3609SSatya Tangirala sb->s_cop->get_devices(sb, devs); 445fee3609SSatya Tangirala } 455fee3609SSatya Tangirala 465fee3609SSatya Tangirala static unsigned int fscrypt_get_dun_bytes(const struct fscrypt_info *ci) 475fee3609SSatya Tangirala { 485fee3609SSatya Tangirala struct super_block *sb = ci->ci_inode->i_sb; 495fee3609SSatya Tangirala unsigned int flags = fscrypt_policy_flags(&ci->ci_policy); 505fee3609SSatya Tangirala int ino_bits = 64, lblk_bits = 64; 515fee3609SSatya Tangirala 525fee3609SSatya Tangirala if (flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) 535fee3609SSatya Tangirala return offsetofend(union fscrypt_iv, nonce); 545fee3609SSatya Tangirala 555fee3609SSatya Tangirala if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) 565fee3609SSatya Tangirala return sizeof(__le64); 575fee3609SSatya Tangirala 585fee3609SSatya Tangirala if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) 595fee3609SSatya Tangirala return sizeof(__le32); 605fee3609SSatya Tangirala 615fee3609SSatya Tangirala /* Default case: IVs are just the file logical block number */ 625fee3609SSatya Tangirala if (sb->s_cop->get_ino_and_lblk_bits) 635fee3609SSatya Tangirala sb->s_cop->get_ino_and_lblk_bits(sb, &ino_bits, &lblk_bits); 645fee3609SSatya Tangirala return DIV_ROUND_UP(lblk_bits, 8); 655fee3609SSatya Tangirala } 665fee3609SSatya Tangirala 675fee3609SSatya Tangirala /* Enable inline encryption for this file if supported. */ 685fee3609SSatya Tangirala int fscrypt_select_encryption_impl(struct fscrypt_info *ci) 695fee3609SSatya Tangirala { 705fee3609SSatya Tangirala const struct inode *inode = ci->ci_inode; 715fee3609SSatya Tangirala struct super_block *sb = inode->i_sb; 725fee3609SSatya Tangirala struct blk_crypto_config crypto_cfg; 735fee3609SSatya Tangirala int num_devs; 745fee3609SSatya Tangirala struct request_queue **devs; 755fee3609SSatya Tangirala int i; 765fee3609SSatya Tangirala 775fee3609SSatya Tangirala /* The file must need contents encryption, not filenames encryption */ 78d19d8d34SEric Biggers if (!S_ISREG(inode->i_mode)) 795fee3609SSatya Tangirala return 0; 805fee3609SSatya Tangirala 815fee3609SSatya Tangirala /* The crypto mode must have a blk-crypto counterpart */ 825fee3609SSatya Tangirala if (ci->ci_mode->blk_crypto_mode == BLK_ENCRYPTION_MODE_INVALID) 835fee3609SSatya Tangirala return 0; 845fee3609SSatya Tangirala 855fee3609SSatya Tangirala /* The filesystem must be mounted with -o inlinecrypt */ 865fee3609SSatya Tangirala if (!(sb->s_flags & SB_INLINECRYPT)) 875fee3609SSatya Tangirala return 0; 885fee3609SSatya Tangirala 895fee3609SSatya Tangirala /* 905fee3609SSatya Tangirala * When a page contains multiple logically contiguous filesystem blocks, 915fee3609SSatya Tangirala * some filesystem code only calls fscrypt_mergeable_bio() for the first 925fee3609SSatya Tangirala * block in the page. This is fine for most of fscrypt's IV generation 935fee3609SSatya Tangirala * strategies, where contiguous blocks imply contiguous IVs. But it 945fee3609SSatya Tangirala * doesn't work with IV_INO_LBLK_32. For now, simply exclude 955fee3609SSatya Tangirala * IV_INO_LBLK_32 with blocksize != PAGE_SIZE from inline encryption. 965fee3609SSatya Tangirala */ 975fee3609SSatya Tangirala if ((fscrypt_policy_flags(&ci->ci_policy) & 985fee3609SSatya Tangirala FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) && 995fee3609SSatya Tangirala sb->s_blocksize != PAGE_SIZE) 1005fee3609SSatya Tangirala return 0; 1015fee3609SSatya Tangirala 1025fee3609SSatya Tangirala /* 1035fee3609SSatya Tangirala * On all the filesystem's devices, blk-crypto must support the crypto 1045fee3609SSatya Tangirala * configuration that the file would use. 1055fee3609SSatya Tangirala */ 1065fee3609SSatya Tangirala crypto_cfg.crypto_mode = ci->ci_mode->blk_crypto_mode; 1075fee3609SSatya Tangirala crypto_cfg.data_unit_size = sb->s_blocksize; 1085fee3609SSatya Tangirala crypto_cfg.dun_bytes = fscrypt_get_dun_bytes(ci); 1095fee3609SSatya Tangirala num_devs = fscrypt_get_num_devices(sb); 1109dad5febSEric Biggers devs = kmalloc_array(num_devs, sizeof(*devs), GFP_KERNEL); 1115fee3609SSatya Tangirala if (!devs) 1125fee3609SSatya Tangirala return -ENOMEM; 1135fee3609SSatya Tangirala fscrypt_get_devices(sb, num_devs, devs); 1145fee3609SSatya Tangirala 1155fee3609SSatya Tangirala for (i = 0; i < num_devs; i++) { 1165fee3609SSatya Tangirala if (!blk_crypto_config_supported(devs[i], &crypto_cfg)) 1175fee3609SSatya Tangirala goto out_free_devs; 1185fee3609SSatya Tangirala } 1195fee3609SSatya Tangirala 1205fee3609SSatya Tangirala ci->ci_inlinecrypt = true; 1215fee3609SSatya Tangirala out_free_devs: 1225fee3609SSatya Tangirala kfree(devs); 1235fee3609SSatya Tangirala 1245fee3609SSatya Tangirala return 0; 1255fee3609SSatya Tangirala } 1265fee3609SSatya Tangirala 1275fee3609SSatya Tangirala int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key, 1285fee3609SSatya Tangirala const u8 *raw_key, 1295fee3609SSatya Tangirala const struct fscrypt_info *ci) 1305fee3609SSatya Tangirala { 1315fee3609SSatya Tangirala const struct inode *inode = ci->ci_inode; 1325fee3609SSatya Tangirala struct super_block *sb = inode->i_sb; 1335fee3609SSatya Tangirala enum blk_crypto_mode_num crypto_mode = ci->ci_mode->blk_crypto_mode; 1345fee3609SSatya Tangirala int num_devs = fscrypt_get_num_devices(sb); 1355fee3609SSatya Tangirala int queue_refs = 0; 1365fee3609SSatya Tangirala struct fscrypt_blk_crypto_key *blk_key; 1375fee3609SSatya Tangirala int err; 1385fee3609SSatya Tangirala int i; 1395fee3609SSatya Tangirala 1409dad5febSEric Biggers blk_key = kzalloc(struct_size(blk_key, devs, num_devs), GFP_KERNEL); 1415fee3609SSatya Tangirala if (!blk_key) 1425fee3609SSatya Tangirala return -ENOMEM; 1435fee3609SSatya Tangirala 1445fee3609SSatya Tangirala blk_key->num_devs = num_devs; 1455fee3609SSatya Tangirala fscrypt_get_devices(sb, num_devs, blk_key->devs); 1465fee3609SSatya Tangirala 1475fee3609SSatya Tangirala err = blk_crypto_init_key(&blk_key->base, raw_key, crypto_mode, 1485fee3609SSatya Tangirala fscrypt_get_dun_bytes(ci), sb->s_blocksize); 1495fee3609SSatya Tangirala if (err) { 1505fee3609SSatya Tangirala fscrypt_err(inode, "error %d initializing blk-crypto key", err); 1515fee3609SSatya Tangirala goto fail; 1525fee3609SSatya Tangirala } 1535fee3609SSatya Tangirala 1545fee3609SSatya Tangirala /* 1555fee3609SSatya Tangirala * We have to start using blk-crypto on all the filesystem's devices. 1565fee3609SSatya Tangirala * We also have to save all the request_queue's for later so that the 1575fee3609SSatya Tangirala * key can be evicted from them. This is needed because some keys 1585fee3609SSatya Tangirala * aren't destroyed until after the filesystem was already unmounted 1595fee3609SSatya Tangirala * (namely, the per-mode keys in struct fscrypt_master_key). 1605fee3609SSatya Tangirala */ 1615fee3609SSatya Tangirala for (i = 0; i < num_devs; i++) { 1625fee3609SSatya Tangirala if (!blk_get_queue(blk_key->devs[i])) { 1635fee3609SSatya Tangirala fscrypt_err(inode, "couldn't get request_queue"); 1645fee3609SSatya Tangirala err = -EAGAIN; 1655fee3609SSatya Tangirala goto fail; 1665fee3609SSatya Tangirala } 1675fee3609SSatya Tangirala queue_refs++; 1685fee3609SSatya Tangirala 1695fee3609SSatya Tangirala err = blk_crypto_start_using_key(&blk_key->base, 1705fee3609SSatya Tangirala blk_key->devs[i]); 1715fee3609SSatya Tangirala if (err) { 1725fee3609SSatya Tangirala fscrypt_err(inode, 1735fee3609SSatya Tangirala "error %d starting to use blk-crypto", err); 1745fee3609SSatya Tangirala goto fail; 1755fee3609SSatya Tangirala } 1765fee3609SSatya Tangirala } 1775fee3609SSatya Tangirala /* 17897c6327fSEric Biggers * Pairs with the smp_load_acquire() in fscrypt_is_key_prepared(). 17997c6327fSEric Biggers * I.e., here we publish ->blk_key with a RELEASE barrier so that 18097c6327fSEric Biggers * concurrent tasks can ACQUIRE it. Note that this concurrency is only 18197c6327fSEric Biggers * possible for per-mode keys, not for per-file keys. 1825fee3609SSatya Tangirala */ 1835fee3609SSatya Tangirala smp_store_release(&prep_key->blk_key, blk_key); 1845fee3609SSatya Tangirala return 0; 1855fee3609SSatya Tangirala 1865fee3609SSatya Tangirala fail: 1875fee3609SSatya Tangirala for (i = 0; i < queue_refs; i++) 1885fee3609SSatya Tangirala blk_put_queue(blk_key->devs[i]); 189453431a5SWaiman Long kfree_sensitive(blk_key); 1905fee3609SSatya Tangirala return err; 1915fee3609SSatya Tangirala } 1925fee3609SSatya Tangirala 1935fee3609SSatya Tangirala void fscrypt_destroy_inline_crypt_key(struct fscrypt_prepared_key *prep_key) 1945fee3609SSatya Tangirala { 1955fee3609SSatya Tangirala struct fscrypt_blk_crypto_key *blk_key = prep_key->blk_key; 1965fee3609SSatya Tangirala int i; 1975fee3609SSatya Tangirala 1985fee3609SSatya Tangirala if (blk_key) { 1995fee3609SSatya Tangirala for (i = 0; i < blk_key->num_devs; i++) { 2005fee3609SSatya Tangirala blk_crypto_evict_key(blk_key->devs[i], &blk_key->base); 2015fee3609SSatya Tangirala blk_put_queue(blk_key->devs[i]); 2025fee3609SSatya Tangirala } 203453431a5SWaiman Long kfree_sensitive(blk_key); 2045fee3609SSatya Tangirala } 2055fee3609SSatya Tangirala } 2065fee3609SSatya Tangirala 2075fee3609SSatya Tangirala bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode) 2085fee3609SSatya Tangirala { 2095fee3609SSatya Tangirala return inode->i_crypt_info->ci_inlinecrypt; 2105fee3609SSatya Tangirala } 2115fee3609SSatya Tangirala EXPORT_SYMBOL_GPL(__fscrypt_inode_uses_inline_crypto); 2125fee3609SSatya Tangirala 2135fee3609SSatya Tangirala static void fscrypt_generate_dun(const struct fscrypt_info *ci, u64 lblk_num, 2145fee3609SSatya Tangirala u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE]) 2155fee3609SSatya Tangirala { 2165fee3609SSatya Tangirala union fscrypt_iv iv; 2175fee3609SSatya Tangirala int i; 2185fee3609SSatya Tangirala 2195fee3609SSatya Tangirala fscrypt_generate_iv(&iv, lblk_num, ci); 2205fee3609SSatya Tangirala 2215fee3609SSatya Tangirala BUILD_BUG_ON(FSCRYPT_MAX_IV_SIZE > BLK_CRYPTO_MAX_IV_SIZE); 2225fee3609SSatya Tangirala memset(dun, 0, BLK_CRYPTO_MAX_IV_SIZE); 2235fee3609SSatya Tangirala for (i = 0; i < ci->ci_mode->ivsize/sizeof(dun[0]); i++) 2245fee3609SSatya Tangirala dun[i] = le64_to_cpu(iv.dun[i]); 2255fee3609SSatya Tangirala } 2265fee3609SSatya Tangirala 2275fee3609SSatya Tangirala /** 2285fee3609SSatya Tangirala * fscrypt_set_bio_crypt_ctx() - prepare a file contents bio for inline crypto 2295fee3609SSatya Tangirala * @bio: a bio which will eventually be submitted to the file 2305fee3609SSatya Tangirala * @inode: the file's inode 2315fee3609SSatya Tangirala * @first_lblk: the first file logical block number in the I/O 2325fee3609SSatya Tangirala * @gfp_mask: memory allocation flags - these must be a waiting mask so that 2335fee3609SSatya Tangirala * bio_crypt_set_ctx can't fail. 2345fee3609SSatya Tangirala * 2355fee3609SSatya Tangirala * If the contents of the file should be encrypted (or decrypted) with inline 2365fee3609SSatya Tangirala * encryption, then assign the appropriate encryption context to the bio. 2375fee3609SSatya Tangirala * 2385fee3609SSatya Tangirala * Normally the bio should be newly allocated (i.e. no pages added yet), as 2395fee3609SSatya Tangirala * otherwise fscrypt_mergeable_bio() won't work as intended. 2405fee3609SSatya Tangirala * 2415fee3609SSatya Tangirala * The encryption context will be freed automatically when the bio is freed. 2425fee3609SSatya Tangirala */ 2435fee3609SSatya Tangirala void fscrypt_set_bio_crypt_ctx(struct bio *bio, const struct inode *inode, 2445fee3609SSatya Tangirala u64 first_lblk, gfp_t gfp_mask) 2455fee3609SSatya Tangirala { 24655e32c54SEric Biggers const struct fscrypt_info *ci; 2475fee3609SSatya Tangirala u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE]; 2485fee3609SSatya Tangirala 2495fee3609SSatya Tangirala if (!fscrypt_inode_uses_inline_crypto(inode)) 2505fee3609SSatya Tangirala return; 25155e32c54SEric Biggers ci = inode->i_crypt_info; 2525fee3609SSatya Tangirala 2535fee3609SSatya Tangirala fscrypt_generate_dun(ci, first_lblk, dun); 2545fee3609SSatya Tangirala bio_crypt_set_ctx(bio, &ci->ci_enc_key.blk_key->base, dun, gfp_mask); 2555fee3609SSatya Tangirala } 2565fee3609SSatya Tangirala EXPORT_SYMBOL_GPL(fscrypt_set_bio_crypt_ctx); 2575fee3609SSatya Tangirala 2585fee3609SSatya Tangirala /* Extract the inode and logical block number from a buffer_head. */ 2595fee3609SSatya Tangirala static bool bh_get_inode_and_lblk_num(const struct buffer_head *bh, 2605fee3609SSatya Tangirala const struct inode **inode_ret, 2615fee3609SSatya Tangirala u64 *lblk_num_ret) 2625fee3609SSatya Tangirala { 2635fee3609SSatya Tangirala struct page *page = bh->b_page; 2645fee3609SSatya Tangirala const struct address_space *mapping; 2655fee3609SSatya Tangirala const struct inode *inode; 2665fee3609SSatya Tangirala 2675fee3609SSatya Tangirala /* 2685fee3609SSatya Tangirala * The ext4 journal (jbd2) can submit a buffer_head it directly created 2695fee3609SSatya Tangirala * for a non-pagecache page. fscrypt doesn't care about these. 2705fee3609SSatya Tangirala */ 2715fee3609SSatya Tangirala mapping = page_mapping(page); 2725fee3609SSatya Tangirala if (!mapping) 2735fee3609SSatya Tangirala return false; 2745fee3609SSatya Tangirala inode = mapping->host; 2755fee3609SSatya Tangirala 2765fee3609SSatya Tangirala *inode_ret = inode; 2775fee3609SSatya Tangirala *lblk_num_ret = ((u64)page->index << (PAGE_SHIFT - inode->i_blkbits)) + 2785fee3609SSatya Tangirala (bh_offset(bh) >> inode->i_blkbits); 2795fee3609SSatya Tangirala return true; 2805fee3609SSatya Tangirala } 2815fee3609SSatya Tangirala 2825fee3609SSatya Tangirala /** 2835fee3609SSatya Tangirala * fscrypt_set_bio_crypt_ctx_bh() - prepare a file contents bio for inline 2845fee3609SSatya Tangirala * crypto 2855fee3609SSatya Tangirala * @bio: a bio which will eventually be submitted to the file 2865fee3609SSatya Tangirala * @first_bh: the first buffer_head for which I/O will be submitted 2875fee3609SSatya Tangirala * @gfp_mask: memory allocation flags 2885fee3609SSatya Tangirala * 2895fee3609SSatya Tangirala * Same as fscrypt_set_bio_crypt_ctx(), except this takes a buffer_head instead 2905fee3609SSatya Tangirala * of an inode and block number directly. 2915fee3609SSatya Tangirala */ 2925fee3609SSatya Tangirala void fscrypt_set_bio_crypt_ctx_bh(struct bio *bio, 2935fee3609SSatya Tangirala const struct buffer_head *first_bh, 2945fee3609SSatya Tangirala gfp_t gfp_mask) 2955fee3609SSatya Tangirala { 2965fee3609SSatya Tangirala const struct inode *inode; 2975fee3609SSatya Tangirala u64 first_lblk; 2985fee3609SSatya Tangirala 2995fee3609SSatya Tangirala if (bh_get_inode_and_lblk_num(first_bh, &inode, &first_lblk)) 3005fee3609SSatya Tangirala fscrypt_set_bio_crypt_ctx(bio, inode, first_lblk, gfp_mask); 3015fee3609SSatya Tangirala } 3025fee3609SSatya Tangirala EXPORT_SYMBOL_GPL(fscrypt_set_bio_crypt_ctx_bh); 3035fee3609SSatya Tangirala 3045fee3609SSatya Tangirala /** 3055fee3609SSatya Tangirala * fscrypt_mergeable_bio() - test whether data can be added to a bio 3065fee3609SSatya Tangirala * @bio: the bio being built up 3075fee3609SSatya Tangirala * @inode: the inode for the next part of the I/O 3085fee3609SSatya Tangirala * @next_lblk: the next file logical block number in the I/O 3095fee3609SSatya Tangirala * 3105fee3609SSatya Tangirala * When building a bio which may contain data which should undergo inline 3115fee3609SSatya Tangirala * encryption (or decryption) via fscrypt, filesystems should call this function 3125fee3609SSatya Tangirala * to ensure that the resulting bio contains only contiguous data unit numbers. 3135fee3609SSatya Tangirala * This will return false if the next part of the I/O cannot be merged with the 3145fee3609SSatya Tangirala * bio because either the encryption key would be different or the encryption 3155fee3609SSatya Tangirala * data unit numbers would be discontiguous. 3165fee3609SSatya Tangirala * 3175fee3609SSatya Tangirala * fscrypt_set_bio_crypt_ctx() must have already been called on the bio. 3185fee3609SSatya Tangirala * 319*c6c89783SEric Biggers * This function isn't required in cases where crypto-mergeability is ensured in 320*c6c89783SEric Biggers * another way, such as I/O targeting only a single file (and thus a single key) 321*c6c89783SEric Biggers * combined with fscrypt_limit_io_blocks() to ensure DUN contiguity. 322*c6c89783SEric Biggers * 3235fee3609SSatya Tangirala * Return: true iff the I/O is mergeable 3245fee3609SSatya Tangirala */ 3255fee3609SSatya Tangirala bool fscrypt_mergeable_bio(struct bio *bio, const struct inode *inode, 3265fee3609SSatya Tangirala u64 next_lblk) 3275fee3609SSatya Tangirala { 3285fee3609SSatya Tangirala const struct bio_crypt_ctx *bc = bio->bi_crypt_context; 3295fee3609SSatya Tangirala u64 next_dun[BLK_CRYPTO_DUN_ARRAY_SIZE]; 3305fee3609SSatya Tangirala 3315fee3609SSatya Tangirala if (!!bc != fscrypt_inode_uses_inline_crypto(inode)) 3325fee3609SSatya Tangirala return false; 3335fee3609SSatya Tangirala if (!bc) 3345fee3609SSatya Tangirala return true; 3355fee3609SSatya Tangirala 3365fee3609SSatya Tangirala /* 3375fee3609SSatya Tangirala * Comparing the key pointers is good enough, as all I/O for each key 3385fee3609SSatya Tangirala * uses the same pointer. I.e., there's currently no need to support 3395fee3609SSatya Tangirala * merging requests where the keys are the same but the pointers differ. 3405fee3609SSatya Tangirala */ 3415fee3609SSatya Tangirala if (bc->bc_key != &inode->i_crypt_info->ci_enc_key.blk_key->base) 3425fee3609SSatya Tangirala return false; 3435fee3609SSatya Tangirala 3445fee3609SSatya Tangirala fscrypt_generate_dun(inode->i_crypt_info, next_lblk, next_dun); 3455fee3609SSatya Tangirala return bio_crypt_dun_is_contiguous(bc, bio->bi_iter.bi_size, next_dun); 3465fee3609SSatya Tangirala } 3475fee3609SSatya Tangirala EXPORT_SYMBOL_GPL(fscrypt_mergeable_bio); 3485fee3609SSatya Tangirala 3495fee3609SSatya Tangirala /** 3505fee3609SSatya Tangirala * fscrypt_mergeable_bio_bh() - test whether data can be added to a bio 3515fee3609SSatya Tangirala * @bio: the bio being built up 3525fee3609SSatya Tangirala * @next_bh: the next buffer_head for which I/O will be submitted 3535fee3609SSatya Tangirala * 3545fee3609SSatya Tangirala * Same as fscrypt_mergeable_bio(), except this takes a buffer_head instead of 3555fee3609SSatya Tangirala * an inode and block number directly. 3565fee3609SSatya Tangirala * 3575fee3609SSatya Tangirala * Return: true iff the I/O is mergeable 3585fee3609SSatya Tangirala */ 3595fee3609SSatya Tangirala bool fscrypt_mergeable_bio_bh(struct bio *bio, 3605fee3609SSatya Tangirala const struct buffer_head *next_bh) 3615fee3609SSatya Tangirala { 3625fee3609SSatya Tangirala const struct inode *inode; 3635fee3609SSatya Tangirala u64 next_lblk; 3645fee3609SSatya Tangirala 3655fee3609SSatya Tangirala if (!bh_get_inode_and_lblk_num(next_bh, &inode, &next_lblk)) 3665fee3609SSatya Tangirala return !bio->bi_crypt_context; 3675fee3609SSatya Tangirala 3685fee3609SSatya Tangirala return fscrypt_mergeable_bio(bio, inode, next_lblk); 3695fee3609SSatya Tangirala } 3705fee3609SSatya Tangirala EXPORT_SYMBOL_GPL(fscrypt_mergeable_bio_bh); 371*c6c89783SEric Biggers 372*c6c89783SEric Biggers /** 373*c6c89783SEric Biggers * fscrypt_dio_supported() - check whether a DIO (direct I/O) request is 374*c6c89783SEric Biggers * supported as far as encryption is concerned 375*c6c89783SEric Biggers * @iocb: the file and position the I/O is targeting 376*c6c89783SEric Biggers * @iter: the I/O data segment(s) 377*c6c89783SEric Biggers * 378*c6c89783SEric Biggers * Return: %true if there are no encryption constraints that prevent DIO from 379*c6c89783SEric Biggers * being supported; %false if DIO is unsupported. (Note that in the 380*c6c89783SEric Biggers * %true case, the filesystem might have other, non-encryption-related 381*c6c89783SEric Biggers * constraints that prevent DIO from actually being supported.) 382*c6c89783SEric Biggers */ 383*c6c89783SEric Biggers bool fscrypt_dio_supported(struct kiocb *iocb, struct iov_iter *iter) 384*c6c89783SEric Biggers { 385*c6c89783SEric Biggers const struct inode *inode = file_inode(iocb->ki_filp); 386*c6c89783SEric Biggers const unsigned int blocksize = i_blocksize(inode); 387*c6c89783SEric Biggers 388*c6c89783SEric Biggers /* If the file is unencrypted, no veto from us. */ 389*c6c89783SEric Biggers if (!fscrypt_needs_contents_encryption(inode)) 390*c6c89783SEric Biggers return true; 391*c6c89783SEric Biggers 392*c6c89783SEric Biggers /* We only support DIO with inline crypto, not fs-layer crypto. */ 393*c6c89783SEric Biggers if (!fscrypt_inode_uses_inline_crypto(inode)) 394*c6c89783SEric Biggers return false; 395*c6c89783SEric Biggers 396*c6c89783SEric Biggers /* 397*c6c89783SEric Biggers * Since the granularity of encryption is filesystem blocks, the file 398*c6c89783SEric Biggers * position and total I/O length must be aligned to the filesystem block 399*c6c89783SEric Biggers * size -- not just to the block device's logical block size as is 400*c6c89783SEric Biggers * traditionally the case for DIO on many filesystems. 401*c6c89783SEric Biggers * 402*c6c89783SEric Biggers * We require that the user-provided memory buffers be filesystem block 403*c6c89783SEric Biggers * aligned too. It is simpler to have a single alignment value required 404*c6c89783SEric Biggers * for all properties of the I/O, as is normally the case for DIO. 405*c6c89783SEric Biggers * Also, allowing less aligned buffers would imply that data units could 406*c6c89783SEric Biggers * cross bvecs, which would greatly complicate the I/O stack, which 407*c6c89783SEric Biggers * assumes that bios can be split at any bvec boundary. 408*c6c89783SEric Biggers */ 409*c6c89783SEric Biggers if (!IS_ALIGNED(iocb->ki_pos | iov_iter_alignment(iter), blocksize)) 410*c6c89783SEric Biggers return false; 411*c6c89783SEric Biggers 412*c6c89783SEric Biggers return true; 413*c6c89783SEric Biggers } 414*c6c89783SEric Biggers EXPORT_SYMBOL_GPL(fscrypt_dio_supported); 415*c6c89783SEric Biggers 416*c6c89783SEric Biggers /** 417*c6c89783SEric Biggers * fscrypt_limit_io_blocks() - limit I/O blocks to avoid discontiguous DUNs 418*c6c89783SEric Biggers * @inode: the file on which I/O is being done 419*c6c89783SEric Biggers * @lblk: the block at which the I/O is being started from 420*c6c89783SEric Biggers * @nr_blocks: the number of blocks we want to submit starting at @lblk 421*c6c89783SEric Biggers * 422*c6c89783SEric Biggers * Determine the limit to the number of blocks that can be submitted in a bio 423*c6c89783SEric Biggers * targeting @lblk without causing a data unit number (DUN) discontiguity. 424*c6c89783SEric Biggers * 425*c6c89783SEric Biggers * This is normally just @nr_blocks, as normally the DUNs just increment along 426*c6c89783SEric Biggers * with the logical blocks. (Or the file is not encrypted.) 427*c6c89783SEric Biggers * 428*c6c89783SEric Biggers * In rare cases, fscrypt can be using an IV generation method that allows the 429*c6c89783SEric Biggers * DUN to wrap around within logically contiguous blocks, and that wraparound 430*c6c89783SEric Biggers * will occur. If this happens, a value less than @nr_blocks will be returned 431*c6c89783SEric Biggers * so that the wraparound doesn't occur in the middle of a bio, which would 432*c6c89783SEric Biggers * cause encryption/decryption to produce wrong results. 433*c6c89783SEric Biggers * 434*c6c89783SEric Biggers * Return: the actual number of blocks that can be submitted 435*c6c89783SEric Biggers */ 436*c6c89783SEric Biggers u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk, u64 nr_blocks) 437*c6c89783SEric Biggers { 438*c6c89783SEric Biggers const struct fscrypt_info *ci; 439*c6c89783SEric Biggers u32 dun; 440*c6c89783SEric Biggers 441*c6c89783SEric Biggers if (!fscrypt_inode_uses_inline_crypto(inode)) 442*c6c89783SEric Biggers return nr_blocks; 443*c6c89783SEric Biggers 444*c6c89783SEric Biggers if (nr_blocks <= 1) 445*c6c89783SEric Biggers return nr_blocks; 446*c6c89783SEric Biggers 447*c6c89783SEric Biggers ci = inode->i_crypt_info; 448*c6c89783SEric Biggers if (!(fscrypt_policy_flags(&ci->ci_policy) & 449*c6c89783SEric Biggers FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) 450*c6c89783SEric Biggers return nr_blocks; 451*c6c89783SEric Biggers 452*c6c89783SEric Biggers /* With IV_INO_LBLK_32, the DUN can wrap around from U32_MAX to 0. */ 453*c6c89783SEric Biggers 454*c6c89783SEric Biggers dun = ci->ci_hashed_ino + lblk; 455*c6c89783SEric Biggers 456*c6c89783SEric Biggers return min_t(u64, nr_blocks, (u64)U32_MAX + 1 - dun); 457*c6c89783SEric Biggers } 458*c6c89783SEric Biggers EXPORT_SYMBOL_GPL(fscrypt_limit_io_blocks); 459