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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416// SPDX-License-Identifier: GPL-2.0/* * File contents en/decryption on block-based filesystems * * Copyright 2019 Google LLC */
/* * This file implements fscrypt's file contents en/decryption using blk-crypto * (Documentation/block/inline-encryption.rst). fscrypt assigns a bio_crypt_ctx * with a key and IV to each bio, and the block layer does the en/decryption. * * This file's exported functions are called only by block-based filesystems. */
#include <linux/blk-crypto.h>#include <linux/blkdev.h>#include <linux/export.h>#include <linux/sched/mm.h>#include <linux/slab.h>#include <linux/uio.h>
#include "fscrypt_private.h"
static unsigned intfscrypt_get_devices(struct super_block *sb, struct block_device *devs[FSCRYPT_MAX_DEVICES]){ if (sb->s_cop->get_devices) return sb->s_cop->get_devices(sb, devs); devs[0] = sb->s_bdev; return 1;}
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 *dev, const struct blk_crypto_key *blk_key){ if (blk_crypto_config_supported_natively(dev, &blk_key->crypto_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); }}
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; bool inlinecrypt = sb->s_flags & SB_INLINECRYPT; struct fscrypt_mode *mode = ci->ci_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[FSCRYPT_MAX_DEVICES]; unsigned int num_devs; unsigned int i; int err;
if (is_hw_wrapped && !inlinecrypt) { /* * blk_crypto_init_key() would catch this anyway, but this * provides a clearer error message. */ fscrypt_err( inode, "Hardware-wrapped keys require inline encryption (-o inlinecrypt)"); return -EINVAL; }
blk_key = kmalloc_obj(*blk_key); if (!blk_key) return -ENOMEM;
err = blk_crypto_init_key(blk_key, key_bytes, key_size, key_type, mode->blk_crypto_mode, fscrypt_get_dun_bytes(ci), 1U << ci->ci_data_unit_bits, inlinecrypt ? BLK_CRYPTO_CFG_ALLOW_HW : 0); 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. */ num_devs = fscrypt_get_devices(sb, devs); for (i = 0; i < num_devs; i++) { err = blk_crypto_start_using_key(devs[i], blk_key); if (err) break; fscrypt_log_blk_crypto_impl(mode, devs[i], blk_key); } if (err) { if (err == -EOPNOTSUPP && is_hw_wrapped) fscrypt_err( inode, "Hardware-wrapped key required, but no suitable inline encryption capabilities are available"); else fscrypt_err(inode, "Error %d starting to use blk-crypto", err); goto fail; }
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[FSCRYPT_MAX_DEVICES]; unsigned int num_devs; unsigned int i;
if (!blk_key) return;
/* * Evict the key from all the filesystem's block devices. * This *must* be done before the key is freed. */ num_devs = fscrypt_get_devices(sb, devs); for (i = 0; i < num_devs; i++) blk_crypto_evict_key(devs[i], blk_key);
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;}
static void fscrypt_generate_dun(const struct fscrypt_inode_info *ci, loff_t pos, u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE]){ union fscrypt_iv iv; int i;
fscrypt_generate_iv(&iv, pos >> ci->ci_data_unit_bits, 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 * @pos: the first file position (in bytes) 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), 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, loff_t pos, gfp_t gfp_mask){ const struct fscrypt_inode_info *ci; u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE];
if (!fscrypt_needs_contents_encryption(inode)) return; ci = fscrypt_get_inode_info_raw(inode);
fscrypt_generate_dun(ci, pos, dun); bio_crypt_set_ctx(bio, ci->ci_enc_key.blk_key, dun, gfp_mask);}EXPORT_SYMBOL_GPL(fscrypt_set_bio_crypt_ctx);
/** * 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 * @pos: the next file position (in bytes) in the I/O * * When building a bio which may contain data which should undergo 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, loff_t pos){ 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_needs_contents_encryption(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, pos, next_dun); return bio_crypt_dun_is_contiguous(bc, bio->bi_iter.bi_size, next_dun);}EXPORT_SYMBOL_GPL(fscrypt_mergeable_bio);
/** * 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_needs_contents_encryption(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);
struct fscrypt_zero_done { atomic_t pending; blk_status_t status; struct completion done;};
static void fscrypt_zeroout_range_done(struct fscrypt_zero_done *done){ if (atomic_dec_and_test(&done->pending)) complete(&done->done);}
static void fscrypt_zeroout_range_end_io(struct bio *bio){ struct fscrypt_zero_done *done = bio->bi_private;
if (bio->bi_status) cmpxchg(&done->status, 0, bio->bi_status); fscrypt_zeroout_range_done(done); bio_put(bio);}
/** * fscrypt_zeroout_range() - zero out a range of blocks in an encrypted file * @inode: the file's inode * @pos: the first file position (in bytes) to zero out * @sector: the first sector to zero out * @len: bytes to zero out * * Zero out filesystem blocks in an encrypted regular file on-disk, i.e. write * ciphertext blocks which decrypt to the all-zeroes block. The blocks must be * both logically and physically contiguous. It's also assumed that the * filesystem only uses a single block device, ->s_bdev. @len must be a * multiple of the file system logical block size. * * Note that since each block uses a different IV, this involves writing a * different ciphertext to each block; we can't simply reuse the same one. * * Return: 0 on success; -errno on failure. */int fscrypt_zeroout_range(const struct inode *inode, loff_t pos, sector_t sector, u64 len){ struct fscrypt_zero_done done = { .pending = ATOMIC_INIT(1), .done = COMPLETION_INITIALIZER_ONSTACK(done.done), };
if (len == 0) return 0;
do { struct bio *bio; unsigned int n;
bio = bio_alloc(inode->i_sb->s_bdev, BIO_MAX_VECS, REQ_OP_WRITE, GFP_NOFS); bio->bi_iter.bi_sector = sector; bio->bi_private = &done; bio->bi_end_io = fscrypt_zeroout_range_end_io; fscrypt_set_bio_crypt_ctx(bio, inode, pos, GFP_NOFS);
for (n = 0; n < BIO_MAX_VECS; n++) { unsigned int bytes_this_page = min(len, PAGE_SIZE);
__bio_add_page(bio, ZERO_PAGE(0), bytes_this_page, 0); len -= bytes_this_page; pos += bytes_this_page; sector += (bytes_this_page >> SECTOR_SHIFT); if (!len || !fscrypt_mergeable_bio(bio, inode, pos)) break; }
atomic_inc(&done.pending); blk_crypto_submit_bio(bio); } while (len);
fscrypt_zeroout_range_done(&done);
wait_for_completion(&done.done); return blk_status_to_errno(done.status);}EXPORT_SYMBOL(fscrypt_zeroout_range);