Orange Pi5 kernel

// 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/keyslot-manager.h>
#include <linux/sched/mm.h>
#include <linux/slab.h>
#include <linux/uio.h>
 
#include "fscrypt_private.h"
 
struct fscrypt_blk_crypto_key {
<------>struct blk_crypto_key base;
<------>int num_devs;
<------>struct request_queue *devs[];
};
 
static int fscrypt_get_num_devices(struct super_block *sb)
{
<------>if (sb->s_cop->get_num_devices)
<------><------>return sb->s_cop->get_num_devices(sb);
<------>return 1;
}
 
static void fscrypt_get_devices(struct super_block *sb, int num_devs,
<------><------><------><------>struct request_queue **devs)
{
<------>if (num_devs == 1)
<------><------>devs[0] = bdev_get_queue(sb->s_bdev);
<------>else
<------><------>sb->s_cop->get_devices(sb, devs);
}
 
static unsigned int fscrypt_get_dun_bytes(const struct fscrypt_info *ci)
{
<------>struct super_block *sb = ci->ci_inode->i_sb;
<------>unsigned int flags = fscrypt_policy_flags(&ci->ci_policy);
<------>int ino_bits = 64, lblk_bits = 64;
 
<------>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 logical block number */
<------>if (sb->s_cop->get_ino_and_lblk_bits)
<------><------>sb->s_cop->get_ino_and_lblk_bits(sb, &ino_bits, &lblk_bits);
<------>return DIV_ROUND_UP(lblk_bits, 8);
}
 
/* Enable inline encryption for this file if supported. */
int fscrypt_select_encryption_impl(struct fscrypt_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;
<------>int num_devs;
<------>struct request_queue **devs;
<------>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 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 = sb->s_blocksize;
<------>crypto_cfg.dun_bytes = fscrypt_get_dun_bytes(ci);
<------>crypto_cfg.is_hw_wrapped = is_hw_wrapped_key;
<------>num_devs = fscrypt_get_num_devices(sb);
<------>devs = kmalloc_array(num_devs, sizeof(*devs), GFP_KERNEL);
<------>if (!devs)
<------><------>return -ENOMEM;
<------>fscrypt_get_devices(sb, num_devs, devs);
 
<------>for (i = 0; i < num_devs; i++) {
<------><------>if (!blk_crypto_config_supported(devs[i], &crypto_cfg))
<------><------><------>goto out_free_devs;
<------>}
 
<------>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 *raw_key,
<------><------><------><------>     unsigned int raw_key_size,
<------><------><------><------>     bool is_hw_wrapped,
<------><------><------><------>     const struct fscrypt_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;
<------>int num_devs = fscrypt_get_num_devices(sb);
<------>int queue_refs = 0;
<------>struct fscrypt_blk_crypto_key *blk_key;
<------>int err;
<------>int i;
 
<------>blk_key = kzalloc(struct_size(blk_key, devs, num_devs), GFP_KERNEL);
<------>if (!blk_key)
<------><------>return -ENOMEM;
 
<------>blk_key->num_devs = num_devs;
<------>fscrypt_get_devices(sb, num_devs, blk_key->devs);
 
<------>BUILD_BUG_ON(FSCRYPT_MAX_HW_WRAPPED_KEY_SIZE >
<------><------>     BLK_CRYPTO_MAX_WRAPPED_KEY_SIZE);
 
<------>err = blk_crypto_init_key(&blk_key->base, raw_key, raw_key_size,
<------><------><------><------>  is_hw_wrapped, crypto_mode,
<------><------><------><------>  fscrypt_get_dun_bytes(ci), sb->s_blocksize);
<------>if (err) {
<------><------>fscrypt_err(inode, "error %d initializing blk-crypto key", err);
<------><------>goto fail;
<------>}
 
<------>/*
<------> * We have to start using blk-crypto on all the filesystem's devices.
<------> * We also have to save all the request_queue's for later so that the
<------> * key can be evicted from them.  This is needed because some keys
<------> * aren't destroyed until after the filesystem was already unmounted
<------> * (namely, the per-mode keys in struct fscrypt_master_key).
<------> */
<------>for (i = 0; i < num_devs; i++) {
<------><------>if (!blk_get_queue(blk_key->devs[i])) {
<------><------><------>fscrypt_err(inode, "couldn't get request_queue");
<------><------><------>err = -EAGAIN;
<------><------><------>goto fail;
<------><------>}
<------><------>queue_refs++;
 
<------><------>err = blk_crypto_start_using_key(&blk_key->base,
<------><------><------><------><------><------> blk_key->devs[i]);
<------><------>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:
<------>for (i = 0; i < queue_refs; i++)
<------><------>blk_put_queue(blk_key->devs[i]);
<------>kfree_sensitive(blk_key);
<------>return err;
}
 
void fscrypt_destroy_inline_crypt_key(struct fscrypt_prepared_key *prep_key)
{
<------>struct fscrypt_blk_crypto_key *blk_key = prep_key->blk_key;
<------>int i;
 
<------>if (blk_key) {
<------><------>for (i = 0; i < blk_key->num_devs; i++) {
<------><------><------>blk_crypto_evict_key(blk_key->devs[i], &blk_key->base);
<------><------><------>blk_put_queue(blk_key->devs[i]);
<------><------>}
<------><------>kfree_sensitive(blk_key);
<------>}
}
 
int fscrypt_derive_raw_secret(struct super_block *sb,
<------><------><------>      const u8 *wrapped_key,
<------><------><------>      unsigned int wrapped_key_size,
<------><------><------>      u8 *raw_secret, unsigned int raw_secret_size)
{
<------>struct request_queue *q;
 
<------>q = bdev_get_queue(sb->s_bdev);
<------>if (!q->ksm)
<------><------>return -EOPNOTSUPP;
 
<------>return blk_ksm_derive_raw_secret(q->ksm, wrapped_key, wrapped_key_size,
<------><------><------><------><------> raw_secret, raw_secret_size);
}
 
bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode)
{
<------>return inode->i_crypt_info->ci_inlinecrypt;
}
EXPORT_SYMBOL_GPL(__fscrypt_inode_uses_inline_crypto);
 
static void fscrypt_generate_dun(const struct fscrypt_info *ci, u64 lblk_num,
<------><------><------><------> u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE])
{
<------>union fscrypt_iv iv;
<------>int i;
 
<------>fscrypt_generate_iv(&iv, lblk_num, 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.
 *
 * This function also handles setting bi_skip_dm_default_key when needed.
 */
void fscrypt_set_bio_crypt_ctx(struct bio *bio, const struct inode *inode,
<------><------><------>       u64 first_lblk, gfp_t gfp_mask)
{
<------>const struct fscrypt_info *ci;
<------>u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE];
 
<------>if (fscrypt_inode_should_skip_dm_default_key(inode))
<------><------>bio_set_skip_dm_default_key(bio);
 
<------>if (!fscrypt_inode_uses_inline_crypto(inode))
<------><------>return;
<------>ci = inode->i_crypt_info;
 
<------>fscrypt_generate_dun(ci, first_lblk, dun);
<------>bio_crypt_set_ctx(bio, &ci->ci_enc_key.blk_key->base, 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 page *page = bh->b_page;
<------>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 = page_mapping(page);
<------>if (!mapping)
<------><------>return false;
<------>inode = mapping->host;
 
<------>*inode_ret = inode;
<------>*lblk_num_ret = ((u64)page->index << (PAGE_SHIFT - inode->i_blkbits)) +
<------><------><------>(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 also returns false if the next part of the I/O would need to
 * have a different value for the bi_skip_dm_default_key flag.
 *
 * 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;
<------>u64 next_dun[BLK_CRYPTO_DUN_ARRAY_SIZE];
 
<------>if (!!bc != fscrypt_inode_uses_inline_crypto(inode))
<------><------>return false;
<------>if (bio_should_skip_dm_default_key(bio) !=
<------>    fscrypt_inode_should_skip_dm_default_key(inode))
<------><------>return false;
<------>if (!bc)
<------><------>return true;
 
<------>/*
<------> * 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 != &inode->i_crypt_info->ci_enc_key.blk_key->base)
<------><------>return false;
 
<------>fscrypt_generate_dun(inode->i_crypt_info, 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 &&
<------><------>       !bio_should_skip_dm_default_key(bio);
 
<------>return fscrypt_mergeable_bio(bio, inode, next_lblk);
}
EXPORT_SYMBOL_GPL(fscrypt_mergeable_bio_bh);
 
/**
 * fscrypt_dio_supported() - check whether a direct I/O request is unsupported
 *			     due to encryption constraints
 * @iocb: the file and position the I/O is targeting
 * @iter: the I/O data segment(s)
 *
 * Return: true if direct I/O is supported
 */
bool fscrypt_dio_supported(struct kiocb *iocb, struct iov_iter *iter)
{
<------>const struct inode *inode = file_inode(iocb->ki_filp);
<------>const unsigned int blocksize = i_blocksize(inode);
 
<------>/* If the file is unencrypted, no veto from us. */
<------>if (!fscrypt_needs_contents_encryption(inode))
<------><------>return true;
 
<------>/* We only support direct I/O with inline crypto, not fs-layer crypto */
<------>if (!fscrypt_inode_uses_inline_crypto(inode))
<------><------>return false;
 
<------>/*
<------> * Since the granularity of encryption is filesystem blocks, the I/O
<------> * must be block aligned -- not just disk sector aligned.
<------> */
<------>if (!IS_ALIGNED(iocb->ki_pos | iov_iter_alignment(iter), blocksize))
<------><------>return false;
 
<------>return true;
}
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 @pos
 *
 * Determine the limit to the number of blocks that can be submitted in the bio
 * targeting @pos without causing a data unit number (DUN) discontinuity.
 *
 * 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 continuous 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 the bio.
 *
 * 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_info *ci = inode->i_crypt_info;
<------>u32 dun;
 
<------>if (!fscrypt_inode_uses_inline_crypto(inode))
<------><------>return nr_blocks;
 
<------>if (nr_blocks <= 1)
<------><------>return nr_blocks;
 
<------>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);