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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
commitace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch)
treeb2d64bc10158fdd5497876388cd68142ca374ed3 /fs/crypto/bio.c
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'fs/crypto/bio.c')
-rw-r--r--fs/crypto/bio.c193
1 files changed, 193 insertions, 0 deletions
diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
new file mode 100644
index 0000000000..62e1a3dd83
--- /dev/null
+++ b/fs/crypto/bio.c
@@ -0,0 +1,193 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Utility functions for file contents encryption/decryption on
+ * block device-based filesystems.
+ *
+ * Copyright (C) 2015, Google, Inc.
+ * Copyright (C) 2015, Motorola Mobility
+ */
+
+#include <linux/pagemap.h>
+#include <linux/module.h>
+#include <linux/bio.h>
+#include <linux/namei.h>
+#include "fscrypt_private.h"
+
+/**
+ * fscrypt_decrypt_bio() - decrypt the contents of a bio
+ * @bio: the bio to decrypt
+ *
+ * Decrypt the contents of a "read" bio following successful completion of the
+ * underlying disk read. The bio must be reading a whole number of blocks of an
+ * encrypted file directly into the page cache. If the bio is reading the
+ * ciphertext into bounce pages instead of the page cache (for example, because
+ * the file is also compressed, so decompression is required after decryption),
+ * then this function isn't applicable. This function may sleep, so it must be
+ * called from a workqueue rather than from the bio's bi_end_io callback.
+ *
+ * Return: %true on success; %false on failure. On failure, bio->bi_status is
+ * also set to an error status.
+ */
+bool fscrypt_decrypt_bio(struct bio *bio)
+{
+ struct folio_iter fi;
+
+ bio_for_each_folio_all(fi, bio) {
+ int err = fscrypt_decrypt_pagecache_blocks(fi.folio, fi.length,
+ fi.offset);
+
+ if (err) {
+ bio->bi_status = errno_to_blk_status(err);
+ return false;
+ }
+ }
+ return true;
+}
+EXPORT_SYMBOL(fscrypt_decrypt_bio);
+
+static int fscrypt_zeroout_range_inline_crypt(const struct inode *inode,
+ pgoff_t lblk, sector_t pblk,
+ unsigned int len)
+{
+ const unsigned int blockbits = inode->i_blkbits;
+ const unsigned int blocks_per_page = 1 << (PAGE_SHIFT - blockbits);
+ struct bio *bio;
+ int ret, err = 0;
+ int num_pages = 0;
+
+ /* This always succeeds since __GFP_DIRECT_RECLAIM is set. */
+ bio = bio_alloc(inode->i_sb->s_bdev, BIO_MAX_VECS, REQ_OP_WRITE,
+ GFP_NOFS);
+
+ while (len) {
+ unsigned int blocks_this_page = min(len, blocks_per_page);
+ unsigned int bytes_this_page = blocks_this_page << blockbits;
+
+ if (num_pages == 0) {
+ fscrypt_set_bio_crypt_ctx(bio, inode, lblk, GFP_NOFS);
+ bio->bi_iter.bi_sector =
+ pblk << (blockbits - SECTOR_SHIFT);
+ }
+ ret = bio_add_page(bio, ZERO_PAGE(0), bytes_this_page, 0);
+ if (WARN_ON_ONCE(ret != bytes_this_page)) {
+ err = -EIO;
+ goto out;
+ }
+ num_pages++;
+ len -= blocks_this_page;
+ lblk += blocks_this_page;
+ pblk += blocks_this_page;
+ if (num_pages == BIO_MAX_VECS || !len ||
+ !fscrypt_mergeable_bio(bio, inode, lblk)) {
+ err = submit_bio_wait(bio);
+ if (err)
+ goto out;
+ bio_reset(bio, inode->i_sb->s_bdev, REQ_OP_WRITE);
+ num_pages = 0;
+ }
+ }
+out:
+ bio_put(bio);
+ return err;
+}
+
+/**
+ * fscrypt_zeroout_range() - zero out a range of blocks in an encrypted file
+ * @inode: the file's inode
+ * @lblk: the first file logical block to zero out
+ * @pblk: the first filesystem physical block to zero out
+ * @len: number of blocks 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.
+ *
+ * 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, pgoff_t lblk,
+ sector_t pblk, unsigned int len)
+{
+ const unsigned int blockbits = inode->i_blkbits;
+ const unsigned int blocksize = 1 << blockbits;
+ const unsigned int blocks_per_page_bits = PAGE_SHIFT - blockbits;
+ const unsigned int blocks_per_page = 1 << blocks_per_page_bits;
+ struct page *pages[16]; /* write up to 16 pages at a time */
+ unsigned int nr_pages;
+ unsigned int i;
+ unsigned int offset;
+ struct bio *bio;
+ int ret, err;
+
+ if (len == 0)
+ return 0;
+
+ if (fscrypt_inode_uses_inline_crypto(inode))
+ return fscrypt_zeroout_range_inline_crypt(inode, lblk, pblk,
+ len);
+
+ BUILD_BUG_ON(ARRAY_SIZE(pages) > BIO_MAX_VECS);
+ nr_pages = min_t(unsigned int, ARRAY_SIZE(pages),
+ (len + blocks_per_page - 1) >> blocks_per_page_bits);
+
+ /*
+ * We need at least one page for ciphertext. Allocate the first one
+ * from a mempool, with __GFP_DIRECT_RECLAIM set so that it can't fail.
+ *
+ * Any additional page allocations are allowed to fail, as they only
+ * help performance, and waiting on the mempool for them could deadlock.
+ */
+ for (i = 0; i < nr_pages; i++) {
+ pages[i] = fscrypt_alloc_bounce_page(i == 0 ? GFP_NOFS :
+ GFP_NOWAIT | __GFP_NOWARN);
+ if (!pages[i])
+ break;
+ }
+ nr_pages = i;
+ if (WARN_ON_ONCE(nr_pages <= 0))
+ return -EINVAL;
+
+ /* This always succeeds since __GFP_DIRECT_RECLAIM is set. */
+ bio = bio_alloc(inode->i_sb->s_bdev, nr_pages, REQ_OP_WRITE, GFP_NOFS);
+
+ do {
+ bio->bi_iter.bi_sector = pblk << (blockbits - 9);
+
+ i = 0;
+ offset = 0;
+ do {
+ err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk,
+ ZERO_PAGE(0), pages[i],
+ blocksize, offset, GFP_NOFS);
+ if (err)
+ goto out;
+ lblk++;
+ pblk++;
+ len--;
+ offset += blocksize;
+ if (offset == PAGE_SIZE || len == 0) {
+ ret = bio_add_page(bio, pages[i++], offset, 0);
+ if (WARN_ON_ONCE(ret != offset)) {
+ err = -EIO;
+ goto out;
+ }
+ offset = 0;
+ }
+ } while (i != nr_pages && len != 0);
+
+ err = submit_bio_wait(bio);
+ if (err)
+ goto out;
+ bio_reset(bio, inode->i_sb->s_bdev, REQ_OP_WRITE);
+ } while (len != 0);
+ err = 0;
+out:
+ bio_put(bio);
+ for (i = 0; i < nr_pages; i++)
+ fscrypt_free_bounce_page(pages[i]);
+ return err;
+}
+EXPORT_SYMBOL(fscrypt_zeroout_range);