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 15a7a5bc5fSEric Biggers #include <linux/blk-crypto-profile.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> 20c6c89783SEric Biggers #include <linux/uio.h> 215fee3609SSatya Tangirala 225fee3609SSatya Tangirala #include "fscrypt_private.h" 235fee3609SSatya Tangirala 24*0e91fc1eSChristoph Hellwig static struct block_device **fscrypt_get_devices(struct super_block *sb, 25*0e91fc1eSChristoph Hellwig unsigned int *num_devs) 265fee3609SSatya Tangirala { 27*0e91fc1eSChristoph Hellwig struct block_device **devs; 285fee3609SSatya Tangirala 29*0e91fc1eSChristoph Hellwig if (sb->s_cop->get_devices) { 30*0e91fc1eSChristoph Hellwig devs = sb->s_cop->get_devices(sb, num_devs); 31*0e91fc1eSChristoph Hellwig if (devs) 32*0e91fc1eSChristoph Hellwig return devs; 33*0e91fc1eSChristoph Hellwig } 34*0e91fc1eSChristoph Hellwig devs = kmalloc(sizeof(*devs), GFP_KERNEL); 35*0e91fc1eSChristoph Hellwig if (!devs) 36*0e91fc1eSChristoph Hellwig return ERR_PTR(-ENOMEM); 37*0e91fc1eSChristoph Hellwig devs[0] = sb->s_bdev; 38*0e91fc1eSChristoph Hellwig *num_devs = 1; 39*0e91fc1eSChristoph Hellwig return devs; 405fee3609SSatya Tangirala } 415fee3609SSatya Tangirala 425fee3609SSatya Tangirala static unsigned int fscrypt_get_dun_bytes(const struct fscrypt_info *ci) 435fee3609SSatya Tangirala { 445fee3609SSatya Tangirala struct super_block *sb = ci->ci_inode->i_sb; 455fee3609SSatya Tangirala unsigned int flags = fscrypt_policy_flags(&ci->ci_policy); 465fee3609SSatya Tangirala int ino_bits = 64, lblk_bits = 64; 475fee3609SSatya Tangirala 485fee3609SSatya Tangirala if (flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) 495fee3609SSatya Tangirala return offsetofend(union fscrypt_iv, nonce); 505fee3609SSatya Tangirala 515fee3609SSatya Tangirala if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) 525fee3609SSatya Tangirala return sizeof(__le64); 535fee3609SSatya Tangirala 545fee3609SSatya Tangirala if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) 555fee3609SSatya Tangirala return sizeof(__le32); 565fee3609SSatya Tangirala 575fee3609SSatya Tangirala /* Default case: IVs are just the file logical block number */ 585fee3609SSatya Tangirala if (sb->s_cop->get_ino_and_lblk_bits) 595fee3609SSatya Tangirala sb->s_cop->get_ino_and_lblk_bits(sb, &ino_bits, &lblk_bits); 605fee3609SSatya Tangirala return DIV_ROUND_UP(lblk_bits, 8); 615fee3609SSatya Tangirala } 625fee3609SSatya Tangirala 63a7a5bc5fSEric Biggers /* 64a7a5bc5fSEric Biggers * Log a message when starting to use blk-crypto (native) or blk-crypto-fallback 65a7a5bc5fSEric Biggers * for an encryption mode for the first time. This is the blk-crypto 66a7a5bc5fSEric Biggers * counterpart to the message logged when starting to use the crypto API for the 67a7a5bc5fSEric Biggers * first time. A limitation is that these messages don't convey which specific 68a7a5bc5fSEric Biggers * filesystems or files are using each implementation. However, *usually* 69a7a5bc5fSEric Biggers * systems use just one implementation per mode, which makes these messages 70a7a5bc5fSEric Biggers * helpful for debugging problems where the "wrong" implementation is used. 71a7a5bc5fSEric Biggers */ 72a7a5bc5fSEric Biggers static void fscrypt_log_blk_crypto_impl(struct fscrypt_mode *mode, 73*0e91fc1eSChristoph Hellwig struct block_device **devs, 74*0e91fc1eSChristoph Hellwig unsigned int num_devs, 75a7a5bc5fSEric Biggers const struct blk_crypto_config *cfg) 76a7a5bc5fSEric Biggers { 77*0e91fc1eSChristoph Hellwig unsigned int i; 78a7a5bc5fSEric Biggers 79a7a5bc5fSEric Biggers for (i = 0; i < num_devs; i++) { 80*0e91fc1eSChristoph Hellwig struct request_queue *q = bdev_get_queue(devs[i]); 81*0e91fc1eSChristoph Hellwig 82a7a5bc5fSEric Biggers if (!IS_ENABLED(CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK) || 83*0e91fc1eSChristoph Hellwig __blk_crypto_cfg_supported(q->crypto_profile, cfg)) { 84a7a5bc5fSEric Biggers if (!xchg(&mode->logged_blk_crypto_native, 1)) 85a7a5bc5fSEric Biggers pr_info("fscrypt: %s using blk-crypto (native)\n", 86a7a5bc5fSEric Biggers mode->friendly_name); 87a7a5bc5fSEric Biggers } else if (!xchg(&mode->logged_blk_crypto_fallback, 1)) { 88a7a5bc5fSEric Biggers pr_info("fscrypt: %s using blk-crypto-fallback\n", 89a7a5bc5fSEric Biggers mode->friendly_name); 90a7a5bc5fSEric Biggers } 91a7a5bc5fSEric Biggers } 92a7a5bc5fSEric Biggers } 93a7a5bc5fSEric Biggers 945fee3609SSatya Tangirala /* Enable inline encryption for this file if supported. */ 955fee3609SSatya Tangirala int fscrypt_select_encryption_impl(struct fscrypt_info *ci) 965fee3609SSatya Tangirala { 975fee3609SSatya Tangirala const struct inode *inode = ci->ci_inode; 985fee3609SSatya Tangirala struct super_block *sb = inode->i_sb; 995fee3609SSatya Tangirala struct blk_crypto_config crypto_cfg; 100*0e91fc1eSChristoph Hellwig struct block_device **devs; 101*0e91fc1eSChristoph Hellwig unsigned int num_devs; 102*0e91fc1eSChristoph Hellwig unsigned int i; 1035fee3609SSatya Tangirala 1045fee3609SSatya Tangirala /* The file must need contents encryption, not filenames encryption */ 105d19d8d34SEric Biggers if (!S_ISREG(inode->i_mode)) 1065fee3609SSatya Tangirala return 0; 1075fee3609SSatya Tangirala 1085fee3609SSatya Tangirala /* The crypto mode must have a blk-crypto counterpart */ 1095fee3609SSatya Tangirala if (ci->ci_mode->blk_crypto_mode == BLK_ENCRYPTION_MODE_INVALID) 1105fee3609SSatya Tangirala return 0; 1115fee3609SSatya Tangirala 1125fee3609SSatya Tangirala /* The filesystem must be mounted with -o inlinecrypt */ 1135fee3609SSatya Tangirala if (!(sb->s_flags & SB_INLINECRYPT)) 1145fee3609SSatya Tangirala return 0; 1155fee3609SSatya Tangirala 1165fee3609SSatya Tangirala /* 1175fee3609SSatya Tangirala * When a page contains multiple logically contiguous filesystem blocks, 1185fee3609SSatya Tangirala * some filesystem code only calls fscrypt_mergeable_bio() for the first 1195fee3609SSatya Tangirala * block in the page. This is fine for most of fscrypt's IV generation 1205fee3609SSatya Tangirala * strategies, where contiguous blocks imply contiguous IVs. But it 1215fee3609SSatya Tangirala * doesn't work with IV_INO_LBLK_32. For now, simply exclude 1225fee3609SSatya Tangirala * IV_INO_LBLK_32 with blocksize != PAGE_SIZE from inline encryption. 1235fee3609SSatya Tangirala */ 1245fee3609SSatya Tangirala if ((fscrypt_policy_flags(&ci->ci_policy) & 1255fee3609SSatya Tangirala FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) && 1265fee3609SSatya Tangirala sb->s_blocksize != PAGE_SIZE) 1275fee3609SSatya Tangirala return 0; 1285fee3609SSatya Tangirala 1295fee3609SSatya Tangirala /* 130*0e91fc1eSChristoph Hellwig * On all the filesystem's block devices, blk-crypto must support the 131*0e91fc1eSChristoph Hellwig * crypto configuration that the file would use. 1325fee3609SSatya Tangirala */ 1335fee3609SSatya Tangirala crypto_cfg.crypto_mode = ci->ci_mode->blk_crypto_mode; 1345fee3609SSatya Tangirala crypto_cfg.data_unit_size = sb->s_blocksize; 1355fee3609SSatya Tangirala crypto_cfg.dun_bytes = fscrypt_get_dun_bytes(ci); 136*0e91fc1eSChristoph Hellwig 137*0e91fc1eSChristoph Hellwig devs = fscrypt_get_devices(sb, &num_devs); 138*0e91fc1eSChristoph Hellwig if (IS_ERR(devs)) 139*0e91fc1eSChristoph Hellwig return PTR_ERR(devs); 1405fee3609SSatya Tangirala 1415fee3609SSatya Tangirala for (i = 0; i < num_devs; i++) { 142*0e91fc1eSChristoph Hellwig if (!blk_crypto_config_supported(bdev_get_queue(devs[i]), 143*0e91fc1eSChristoph Hellwig &crypto_cfg)) 1445fee3609SSatya Tangirala goto out_free_devs; 1455fee3609SSatya Tangirala } 1465fee3609SSatya Tangirala 147a7a5bc5fSEric Biggers fscrypt_log_blk_crypto_impl(ci->ci_mode, devs, num_devs, &crypto_cfg); 148a7a5bc5fSEric Biggers 1495fee3609SSatya Tangirala ci->ci_inlinecrypt = true; 1505fee3609SSatya Tangirala out_free_devs: 1515fee3609SSatya Tangirala kfree(devs); 1525fee3609SSatya Tangirala 1535fee3609SSatya Tangirala return 0; 1545fee3609SSatya Tangirala } 1555fee3609SSatya Tangirala 1565fee3609SSatya Tangirala int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key, 1575fee3609SSatya Tangirala const u8 *raw_key, 1585fee3609SSatya Tangirala const struct fscrypt_info *ci) 1595fee3609SSatya Tangirala { 1605fee3609SSatya Tangirala const struct inode *inode = ci->ci_inode; 1615fee3609SSatya Tangirala struct super_block *sb = inode->i_sb; 1625fee3609SSatya Tangirala enum blk_crypto_mode_num crypto_mode = ci->ci_mode->blk_crypto_mode; 16322e9947aSEric Biggers struct blk_crypto_key *blk_key; 164*0e91fc1eSChristoph Hellwig struct block_device **devs; 16522e9947aSEric Biggers unsigned int num_devs; 16622e9947aSEric Biggers unsigned int i; 1675fee3609SSatya Tangirala int err; 1685fee3609SSatya Tangirala 16922e9947aSEric Biggers blk_key = kmalloc(sizeof(*blk_key), GFP_KERNEL); 1705fee3609SSatya Tangirala if (!blk_key) 1715fee3609SSatya Tangirala return -ENOMEM; 1725fee3609SSatya Tangirala 17322e9947aSEric Biggers err = blk_crypto_init_key(blk_key, raw_key, crypto_mode, 1745fee3609SSatya Tangirala fscrypt_get_dun_bytes(ci), sb->s_blocksize); 1755fee3609SSatya Tangirala if (err) { 1765fee3609SSatya Tangirala fscrypt_err(inode, "error %d initializing blk-crypto key", err); 1775fee3609SSatya Tangirala goto fail; 1785fee3609SSatya Tangirala } 1795fee3609SSatya Tangirala 18022e9947aSEric Biggers /* Start using blk-crypto on all the filesystem's block devices. */ 181*0e91fc1eSChristoph Hellwig devs = fscrypt_get_devices(sb, &num_devs); 182*0e91fc1eSChristoph Hellwig if (IS_ERR(devs)) { 183*0e91fc1eSChristoph Hellwig err = PTR_ERR(devs); 18422e9947aSEric Biggers goto fail; 18522e9947aSEric Biggers } 1865fee3609SSatya Tangirala for (i = 0; i < num_devs; i++) { 187*0e91fc1eSChristoph Hellwig err = blk_crypto_start_using_key(blk_key, 188*0e91fc1eSChristoph Hellwig bdev_get_queue(devs[i])); 18922e9947aSEric Biggers if (err) 19022e9947aSEric Biggers break; 1915fee3609SSatya Tangirala } 19222e9947aSEric Biggers kfree(devs); 1935fee3609SSatya Tangirala if (err) { 19422e9947aSEric Biggers fscrypt_err(inode, "error %d starting to use blk-crypto", err); 1955fee3609SSatya Tangirala goto fail; 1965fee3609SSatya Tangirala } 19722e9947aSEric Biggers 1985fee3609SSatya Tangirala /* 19997c6327fSEric Biggers * Pairs with the smp_load_acquire() in fscrypt_is_key_prepared(). 20097c6327fSEric Biggers * I.e., here we publish ->blk_key with a RELEASE barrier so that 20197c6327fSEric Biggers * concurrent tasks can ACQUIRE it. Note that this concurrency is only 20297c6327fSEric Biggers * possible for per-mode keys, not for per-file keys. 2035fee3609SSatya Tangirala */ 2045fee3609SSatya Tangirala smp_store_release(&prep_key->blk_key, blk_key); 2055fee3609SSatya Tangirala return 0; 2065fee3609SSatya Tangirala 2075fee3609SSatya Tangirala fail: 208453431a5SWaiman Long kfree_sensitive(blk_key); 2095fee3609SSatya Tangirala return err; 2105fee3609SSatya Tangirala } 2115fee3609SSatya Tangirala 21222e9947aSEric Biggers void fscrypt_destroy_inline_crypt_key(struct super_block *sb, 21322e9947aSEric Biggers struct fscrypt_prepared_key *prep_key) 2145fee3609SSatya Tangirala { 21522e9947aSEric Biggers struct blk_crypto_key *blk_key = prep_key->blk_key; 216*0e91fc1eSChristoph Hellwig struct block_device **devs; 21722e9947aSEric Biggers unsigned int num_devs; 21822e9947aSEric Biggers unsigned int i; 2195fee3609SSatya Tangirala 22022e9947aSEric Biggers if (!blk_key) 22122e9947aSEric Biggers return; 22222e9947aSEric Biggers 22322e9947aSEric Biggers /* Evict the key from all the filesystem's block devices. */ 224*0e91fc1eSChristoph Hellwig devs = fscrypt_get_devices(sb, &num_devs); 225*0e91fc1eSChristoph Hellwig if (!IS_ERR(devs)) { 22622e9947aSEric Biggers for (i = 0; i < num_devs; i++) 227*0e91fc1eSChristoph Hellwig blk_crypto_evict_key(bdev_get_queue(devs[i]), blk_key); 22822e9947aSEric Biggers kfree(devs); 2295fee3609SSatya Tangirala } 230453431a5SWaiman Long kfree_sensitive(blk_key); 2315fee3609SSatya Tangirala } 2325fee3609SSatya Tangirala 2335fee3609SSatya Tangirala bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode) 2345fee3609SSatya Tangirala { 2355fee3609SSatya Tangirala return inode->i_crypt_info->ci_inlinecrypt; 2365fee3609SSatya Tangirala } 2375fee3609SSatya Tangirala EXPORT_SYMBOL_GPL(__fscrypt_inode_uses_inline_crypto); 2385fee3609SSatya Tangirala 2395fee3609SSatya Tangirala static void fscrypt_generate_dun(const struct fscrypt_info *ci, u64 lblk_num, 2405fee3609SSatya Tangirala u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE]) 2415fee3609SSatya Tangirala { 2425fee3609SSatya Tangirala union fscrypt_iv iv; 2435fee3609SSatya Tangirala int i; 2445fee3609SSatya Tangirala 2455fee3609SSatya Tangirala fscrypt_generate_iv(&iv, lblk_num, ci); 2465fee3609SSatya Tangirala 2475fee3609SSatya Tangirala BUILD_BUG_ON(FSCRYPT_MAX_IV_SIZE > BLK_CRYPTO_MAX_IV_SIZE); 2485fee3609SSatya Tangirala memset(dun, 0, BLK_CRYPTO_MAX_IV_SIZE); 2495fee3609SSatya Tangirala for (i = 0; i < ci->ci_mode->ivsize/sizeof(dun[0]); i++) 2505fee3609SSatya Tangirala dun[i] = le64_to_cpu(iv.dun[i]); 2515fee3609SSatya Tangirala } 2525fee3609SSatya Tangirala 2535fee3609SSatya Tangirala /** 2545fee3609SSatya Tangirala * fscrypt_set_bio_crypt_ctx() - prepare a file contents bio for inline crypto 2555fee3609SSatya Tangirala * @bio: a bio which will eventually be submitted to the file 2565fee3609SSatya Tangirala * @inode: the file's inode 2575fee3609SSatya Tangirala * @first_lblk: the first file logical block number in the I/O 2585fee3609SSatya Tangirala * @gfp_mask: memory allocation flags - these must be a waiting mask so that 2595fee3609SSatya Tangirala * bio_crypt_set_ctx can't fail. 2605fee3609SSatya Tangirala * 2615fee3609SSatya Tangirala * If the contents of the file should be encrypted (or decrypted) with inline 2625fee3609SSatya Tangirala * encryption, then assign the appropriate encryption context to the bio. 2635fee3609SSatya Tangirala * 2645fee3609SSatya Tangirala * Normally the bio should be newly allocated (i.e. no pages added yet), as 2655fee3609SSatya Tangirala * otherwise fscrypt_mergeable_bio() won't work as intended. 2665fee3609SSatya Tangirala * 2675fee3609SSatya Tangirala * The encryption context will be freed automatically when the bio is freed. 2685fee3609SSatya Tangirala */ 2695fee3609SSatya Tangirala void fscrypt_set_bio_crypt_ctx(struct bio *bio, const struct inode *inode, 2705fee3609SSatya Tangirala u64 first_lblk, gfp_t gfp_mask) 2715fee3609SSatya Tangirala { 27255e32c54SEric Biggers const struct fscrypt_info *ci; 2735fee3609SSatya Tangirala u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE]; 2745fee3609SSatya Tangirala 2755fee3609SSatya Tangirala if (!fscrypt_inode_uses_inline_crypto(inode)) 2765fee3609SSatya Tangirala return; 27755e32c54SEric Biggers ci = inode->i_crypt_info; 2785fee3609SSatya Tangirala 2795fee3609SSatya Tangirala fscrypt_generate_dun(ci, first_lblk, dun); 28022e9947aSEric Biggers bio_crypt_set_ctx(bio, ci->ci_enc_key.blk_key, dun, gfp_mask); 2815fee3609SSatya Tangirala } 2825fee3609SSatya Tangirala EXPORT_SYMBOL_GPL(fscrypt_set_bio_crypt_ctx); 2835fee3609SSatya Tangirala 2845fee3609SSatya Tangirala /* Extract the inode and logical block number from a buffer_head. */ 2855fee3609SSatya Tangirala static bool bh_get_inode_and_lblk_num(const struct buffer_head *bh, 2865fee3609SSatya Tangirala const struct inode **inode_ret, 2875fee3609SSatya Tangirala u64 *lblk_num_ret) 2885fee3609SSatya Tangirala { 2895fee3609SSatya Tangirala struct page *page = bh->b_page; 2905fee3609SSatya Tangirala const struct address_space *mapping; 2915fee3609SSatya Tangirala const struct inode *inode; 2925fee3609SSatya Tangirala 2935fee3609SSatya Tangirala /* 2945fee3609SSatya Tangirala * The ext4 journal (jbd2) can submit a buffer_head it directly created 2955fee3609SSatya Tangirala * for a non-pagecache page. fscrypt doesn't care about these. 2965fee3609SSatya Tangirala */ 2975fee3609SSatya Tangirala mapping = page_mapping(page); 2985fee3609SSatya Tangirala if (!mapping) 2995fee3609SSatya Tangirala return false; 3005fee3609SSatya Tangirala inode = mapping->host; 3015fee3609SSatya Tangirala 3025fee3609SSatya Tangirala *inode_ret = inode; 3035fee3609SSatya Tangirala *lblk_num_ret = ((u64)page->index << (PAGE_SHIFT - inode->i_blkbits)) + 3045fee3609SSatya Tangirala (bh_offset(bh) >> inode->i_blkbits); 3055fee3609SSatya Tangirala return true; 3065fee3609SSatya Tangirala } 3075fee3609SSatya Tangirala 3085fee3609SSatya Tangirala /** 3095fee3609SSatya Tangirala * fscrypt_set_bio_crypt_ctx_bh() - prepare a file contents bio for inline 3105fee3609SSatya Tangirala * crypto 3115fee3609SSatya Tangirala * @bio: a bio which will eventually be submitted to the file 3125fee3609SSatya Tangirala * @first_bh: the first buffer_head for which I/O will be submitted 3135fee3609SSatya Tangirala * @gfp_mask: memory allocation flags 3145fee3609SSatya Tangirala * 3155fee3609SSatya Tangirala * Same as fscrypt_set_bio_crypt_ctx(), except this takes a buffer_head instead 3165fee3609SSatya Tangirala * of an inode and block number directly. 3175fee3609SSatya Tangirala */ 3185fee3609SSatya Tangirala void fscrypt_set_bio_crypt_ctx_bh(struct bio *bio, 3195fee3609SSatya Tangirala const struct buffer_head *first_bh, 3205fee3609SSatya Tangirala gfp_t gfp_mask) 3215fee3609SSatya Tangirala { 3225fee3609SSatya Tangirala const struct inode *inode; 3235fee3609SSatya Tangirala u64 first_lblk; 3245fee3609SSatya Tangirala 3255fee3609SSatya Tangirala if (bh_get_inode_and_lblk_num(first_bh, &inode, &first_lblk)) 3265fee3609SSatya Tangirala fscrypt_set_bio_crypt_ctx(bio, inode, first_lblk, gfp_mask); 3275fee3609SSatya Tangirala } 3285fee3609SSatya Tangirala EXPORT_SYMBOL_GPL(fscrypt_set_bio_crypt_ctx_bh); 3295fee3609SSatya Tangirala 3305fee3609SSatya Tangirala /** 3315fee3609SSatya Tangirala * fscrypt_mergeable_bio() - test whether data can be added to a bio 3325fee3609SSatya Tangirala * @bio: the bio being built up 3335fee3609SSatya Tangirala * @inode: the inode for the next part of the I/O 3345fee3609SSatya Tangirala * @next_lblk: the next file logical block number in the I/O 3355fee3609SSatya Tangirala * 3365fee3609SSatya Tangirala * When building a bio which may contain data which should undergo inline 3375fee3609SSatya Tangirala * encryption (or decryption) via fscrypt, filesystems should call this function 3385fee3609SSatya Tangirala * to ensure that the resulting bio contains only contiguous data unit numbers. 3395fee3609SSatya Tangirala * This will return false if the next part of the I/O cannot be merged with the 3405fee3609SSatya Tangirala * bio because either the encryption key would be different or the encryption 3415fee3609SSatya Tangirala * data unit numbers would be discontiguous. 3425fee3609SSatya Tangirala * 3435fee3609SSatya Tangirala * fscrypt_set_bio_crypt_ctx() must have already been called on the bio. 3445fee3609SSatya Tangirala * 345c6c89783SEric Biggers * This function isn't required in cases where crypto-mergeability is ensured in 346c6c89783SEric Biggers * another way, such as I/O targeting only a single file (and thus a single key) 347c6c89783SEric Biggers * combined with fscrypt_limit_io_blocks() to ensure DUN contiguity. 348c6c89783SEric Biggers * 3495fee3609SSatya Tangirala * Return: true iff the I/O is mergeable 3505fee3609SSatya Tangirala */ 3515fee3609SSatya Tangirala bool fscrypt_mergeable_bio(struct bio *bio, const struct inode *inode, 3525fee3609SSatya Tangirala u64 next_lblk) 3535fee3609SSatya Tangirala { 3545fee3609SSatya Tangirala const struct bio_crypt_ctx *bc = bio->bi_crypt_context; 3555fee3609SSatya Tangirala u64 next_dun[BLK_CRYPTO_DUN_ARRAY_SIZE]; 3565fee3609SSatya Tangirala 3575fee3609SSatya Tangirala if (!!bc != fscrypt_inode_uses_inline_crypto(inode)) 3585fee3609SSatya Tangirala return false; 3595fee3609SSatya Tangirala if (!bc) 3605fee3609SSatya Tangirala return true; 3615fee3609SSatya Tangirala 3625fee3609SSatya Tangirala /* 3635fee3609SSatya Tangirala * Comparing the key pointers is good enough, as all I/O for each key 3645fee3609SSatya Tangirala * uses the same pointer. I.e., there's currently no need to support 3655fee3609SSatya Tangirala * merging requests where the keys are the same but the pointers differ. 3665fee3609SSatya Tangirala */ 36722e9947aSEric Biggers if (bc->bc_key != inode->i_crypt_info->ci_enc_key.blk_key) 3685fee3609SSatya Tangirala return false; 3695fee3609SSatya Tangirala 3705fee3609SSatya Tangirala fscrypt_generate_dun(inode->i_crypt_info, next_lblk, next_dun); 3715fee3609SSatya Tangirala return bio_crypt_dun_is_contiguous(bc, bio->bi_iter.bi_size, next_dun); 3725fee3609SSatya Tangirala } 3735fee3609SSatya Tangirala EXPORT_SYMBOL_GPL(fscrypt_mergeable_bio); 3745fee3609SSatya Tangirala 3755fee3609SSatya Tangirala /** 3765fee3609SSatya Tangirala * fscrypt_mergeable_bio_bh() - test whether data can be added to a bio 3775fee3609SSatya Tangirala * @bio: the bio being built up 3785fee3609SSatya Tangirala * @next_bh: the next buffer_head for which I/O will be submitted 3795fee3609SSatya Tangirala * 3805fee3609SSatya Tangirala * Same as fscrypt_mergeable_bio(), except this takes a buffer_head instead of 3815fee3609SSatya Tangirala * an inode and block number directly. 3825fee3609SSatya Tangirala * 3835fee3609SSatya Tangirala * Return: true iff the I/O is mergeable 3845fee3609SSatya Tangirala */ 3855fee3609SSatya Tangirala bool fscrypt_mergeable_bio_bh(struct bio *bio, 3865fee3609SSatya Tangirala const struct buffer_head *next_bh) 3875fee3609SSatya Tangirala { 3885fee3609SSatya Tangirala const struct inode *inode; 3895fee3609SSatya Tangirala u64 next_lblk; 3905fee3609SSatya Tangirala 3915fee3609SSatya Tangirala if (!bh_get_inode_and_lblk_num(next_bh, &inode, &next_lblk)) 3925fee3609SSatya Tangirala return !bio->bi_crypt_context; 3935fee3609SSatya Tangirala 3945fee3609SSatya Tangirala return fscrypt_mergeable_bio(bio, inode, next_lblk); 3955fee3609SSatya Tangirala } 3965fee3609SSatya Tangirala EXPORT_SYMBOL_GPL(fscrypt_mergeable_bio_bh); 397c6c89783SEric Biggers 398c6c89783SEric Biggers /** 399c6c89783SEric Biggers * fscrypt_dio_supported() - check whether a DIO (direct I/O) request is 400c6c89783SEric Biggers * supported as far as encryption is concerned 401c6c89783SEric Biggers * @iocb: the file and position the I/O is targeting 402c6c89783SEric Biggers * @iter: the I/O data segment(s) 403c6c89783SEric Biggers * 404c6c89783SEric Biggers * Return: %true if there are no encryption constraints that prevent DIO from 405c6c89783SEric Biggers * being supported; %false if DIO is unsupported. (Note that in the 406c6c89783SEric Biggers * %true case, the filesystem might have other, non-encryption-related 407c6c89783SEric Biggers * constraints that prevent DIO from actually being supported.) 408c6c89783SEric Biggers */ 409c6c89783SEric Biggers bool fscrypt_dio_supported(struct kiocb *iocb, struct iov_iter *iter) 410c6c89783SEric Biggers { 411c6c89783SEric Biggers const struct inode *inode = file_inode(iocb->ki_filp); 412c6c89783SEric Biggers const unsigned int blocksize = i_blocksize(inode); 413c6c89783SEric Biggers 414c6c89783SEric Biggers /* If the file is unencrypted, no veto from us. */ 415c6c89783SEric Biggers if (!fscrypt_needs_contents_encryption(inode)) 416c6c89783SEric Biggers return true; 417c6c89783SEric Biggers 418c6c89783SEric Biggers /* We only support DIO with inline crypto, not fs-layer crypto. */ 419c6c89783SEric Biggers if (!fscrypt_inode_uses_inline_crypto(inode)) 420c6c89783SEric Biggers return false; 421c6c89783SEric Biggers 422c6c89783SEric Biggers /* 423c6c89783SEric Biggers * Since the granularity of encryption is filesystem blocks, the file 424c6c89783SEric Biggers * position and total I/O length must be aligned to the filesystem block 425c6c89783SEric Biggers * size -- not just to the block device's logical block size as is 426c6c89783SEric Biggers * traditionally the case for DIO on many filesystems. 427c6c89783SEric Biggers * 428c6c89783SEric Biggers * We require that the user-provided memory buffers be filesystem block 429c6c89783SEric Biggers * aligned too. It is simpler to have a single alignment value required 430c6c89783SEric Biggers * for all properties of the I/O, as is normally the case for DIO. 431c6c89783SEric Biggers * Also, allowing less aligned buffers would imply that data units could 432c6c89783SEric Biggers * cross bvecs, which would greatly complicate the I/O stack, which 433c6c89783SEric Biggers * assumes that bios can be split at any bvec boundary. 434c6c89783SEric Biggers */ 435c6c89783SEric Biggers if (!IS_ALIGNED(iocb->ki_pos | iov_iter_alignment(iter), blocksize)) 436c6c89783SEric Biggers return false; 437c6c89783SEric Biggers 438c6c89783SEric Biggers return true; 439c6c89783SEric Biggers } 440c6c89783SEric Biggers EXPORT_SYMBOL_GPL(fscrypt_dio_supported); 441c6c89783SEric Biggers 442c6c89783SEric Biggers /** 443c6c89783SEric Biggers * fscrypt_limit_io_blocks() - limit I/O blocks to avoid discontiguous DUNs 444c6c89783SEric Biggers * @inode: the file on which I/O is being done 445c6c89783SEric Biggers * @lblk: the block at which the I/O is being started from 446c6c89783SEric Biggers * @nr_blocks: the number of blocks we want to submit starting at @lblk 447c6c89783SEric Biggers * 448c6c89783SEric Biggers * Determine the limit to the number of blocks that can be submitted in a bio 449c6c89783SEric Biggers * targeting @lblk without causing a data unit number (DUN) discontiguity. 450c6c89783SEric Biggers * 451c6c89783SEric Biggers * This is normally just @nr_blocks, as normally the DUNs just increment along 452c6c89783SEric Biggers * with the logical blocks. (Or the file is not encrypted.) 453c6c89783SEric Biggers * 454c6c89783SEric Biggers * In rare cases, fscrypt can be using an IV generation method that allows the 455c6c89783SEric Biggers * DUN to wrap around within logically contiguous blocks, and that wraparound 456c6c89783SEric Biggers * will occur. If this happens, a value less than @nr_blocks will be returned 457c6c89783SEric Biggers * so that the wraparound doesn't occur in the middle of a bio, which would 458c6c89783SEric Biggers * cause encryption/decryption to produce wrong results. 459c6c89783SEric Biggers * 460c6c89783SEric Biggers * Return: the actual number of blocks that can be submitted 461c6c89783SEric Biggers */ 462c6c89783SEric Biggers u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk, u64 nr_blocks) 463c6c89783SEric Biggers { 464c6c89783SEric Biggers const struct fscrypt_info *ci; 465c6c89783SEric Biggers u32 dun; 466c6c89783SEric Biggers 467c6c89783SEric Biggers if (!fscrypt_inode_uses_inline_crypto(inode)) 468c6c89783SEric Biggers return nr_blocks; 469c6c89783SEric Biggers 470c6c89783SEric Biggers if (nr_blocks <= 1) 471c6c89783SEric Biggers return nr_blocks; 472c6c89783SEric Biggers 473c6c89783SEric Biggers ci = inode->i_crypt_info; 474c6c89783SEric Biggers if (!(fscrypt_policy_flags(&ci->ci_policy) & 475c6c89783SEric Biggers FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) 476c6c89783SEric Biggers return nr_blocks; 477c6c89783SEric Biggers 478c6c89783SEric Biggers /* With IV_INO_LBLK_32, the DUN can wrap around from U32_MAX to 0. */ 479c6c89783SEric Biggers 480c6c89783SEric Biggers dun = ci->ci_hashed_ino + lblk; 481c6c89783SEric Biggers 482c6c89783SEric Biggers return min_t(u64, nr_blocks, (u64)U32_MAX + 1 - dun); 483c6c89783SEric Biggers } 484c6c89783SEric Biggers EXPORT_SYMBOL_GPL(fscrypt_limit_io_blocks); 485