From 31fb992ce675ec3326dfd4db9634480391713db8 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Tue, 22 Oct 2019 20:33:11 -0700 Subject: 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 Signed-off-by: Eric Biggers Link: https://lore.kernel.org/r/20191023033312.361355-2-ebiggers@kernel.org Signed-off-by: Theodore Ts'o --- fs/buffer.c | 48 +++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 43 insertions(+), 5 deletions(-) (limited to 'fs/buffer.c') 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 #include #include +#include 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); } -- cgit v1.2.3-59-g8ed1b