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authorEric Biggers <ebiggers@google.com>2019-10-22 20:33:11 -0700
committerTheodore Ts'o <tytso@mit.edu>2019-11-14 16:40:45 -0500
commit31fb992ce675ec3326dfd4db9634480391713db8 (patch)
tree846219c2af7b9939c6ff12399616799602713f72 /fs/buffer.c
parent4d06bfb97ecb0df4f5b057a73db002e28c22c35c (diff)
fs/buffer.c: support fscrypt in block_read_full_page()
After each filesystem block (as represented by a buffer_head) has been read from disk by block_read_full_page(), decrypt it if needed. The decryption is done on the fscrypt_read_workqueue. This is the final change needed to support ext4 encryption with blocksize != PAGE_SIZE, and it's a fairly small change now that CONFIG_FS_ENCRYPTION is a bool and fs/crypto/ exposes functions to decrypt individual blocks and to enqueue work on the fscrypt workqueue. Don't try to add fs-verity support yet, as the fs/verity/ support layer isn't ready for sub-page blocks yet. Just add fscrypt support for now. Almost all the new code is compiled away when CONFIG_FS_ENCRYPTION=n. Cc: Chandan Rajendra <chandan@linux.ibm.com> Signed-off-by: Eric Biggers <ebiggers@google.com> Link: https://lore.kernel.org/r/20191023033312.361355-2-ebiggers@kernel.org Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/buffer.c')
-rw-r--r--fs/buffer.c48
1 files changed, 43 insertions, 5 deletions
diff --git a/fs/buffer.c b/fs/buffer.c
index 86a38b979323..d39838090b22 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -47,6 +47,7 @@
#include <linux/pagevec.h>
#include <linux/sched/mm.h>
#include <trace/events/block.h>
+#include <linux/fscrypt.h>
static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh,
@@ -246,10 +247,6 @@ out:
return ret;
}
-/*
- * I/O completion handler for block_read_full_page() - pages
- * which come unlocked at the end of I/O.
- */
static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
{
unsigned long flags;
@@ -307,6 +304,47 @@ still_busy:
return;
}
+struct decrypt_bh_ctx {
+ struct work_struct work;
+ struct buffer_head *bh;
+};
+
+static void decrypt_bh(struct work_struct *work)
+{
+ struct decrypt_bh_ctx *ctx =
+ container_of(work, struct decrypt_bh_ctx, work);
+ struct buffer_head *bh = ctx->bh;
+ int err;
+
+ err = fscrypt_decrypt_pagecache_blocks(bh->b_page, bh->b_size,
+ bh_offset(bh));
+ end_buffer_async_read(bh, err == 0);
+ kfree(ctx);
+}
+
+/*
+ * I/O completion handler for block_read_full_page() - pages
+ * which come unlocked at the end of I/O.
+ */
+static void end_buffer_async_read_io(struct buffer_head *bh, int uptodate)
+{
+ /* Decrypt if needed */
+ if (uptodate && IS_ENABLED(CONFIG_FS_ENCRYPTION) &&
+ IS_ENCRYPTED(bh->b_page->mapping->host) &&
+ S_ISREG(bh->b_page->mapping->host->i_mode)) {
+ struct decrypt_bh_ctx *ctx = kmalloc(sizeof(*ctx), GFP_ATOMIC);
+
+ if (ctx) {
+ INIT_WORK(&ctx->work, decrypt_bh);
+ ctx->bh = bh;
+ fscrypt_enqueue_decrypt_work(&ctx->work);
+ return;
+ }
+ uptodate = 0;
+ }
+ end_buffer_async_read(bh, uptodate);
+}
+
/*
* Completion handler for block_write_full_page() - pages which are unlocked
* during I/O, and which have PageWriteback cleared upon I/O completion.
@@ -379,7 +417,7 @@ EXPORT_SYMBOL(end_buffer_async_write);
*/
static void mark_buffer_async_read(struct buffer_head *bh)
{
- bh->b_end_io = end_buffer_async_read;
+ bh->b_end_io = end_buffer_async_read_io;
set_buffer_async_read(bh);
}