Merge tag 'fsverity-for-linus' of git://git.kernel.org/pub/scm/fs/fsverity/linux

Pull fsverity updates from Eric Biggers:
 "Fix the longstanding implementation limitation that fsverity was only
  supported when the Merkle tree block size, filesystem block size, and
  PAGE_SIZE were all equal.

  Specifically, add support for Merkle tree block sizes less than
  PAGE_SIZE, and make ext4 support fsverity on filesystems where the
  filesystem block size is less than PAGE_SIZE.

  Effectively, this means that fsverity can now be used on systems with
  non-4K pages, at least on ext4. These changes have been tested using
  the verity group of xfstests, newly updated to cover the new code
  paths.

  Also update fs/verity/ to support verifying data from large folios.

  There's also a similar patch for fs/crypto/, to support decrypting
  data from large folios, which I'm including in here to avoid a merge
  conflict between the fscrypt and fsverity branches"

* tag 'fsverity-for-linus' of git://git.kernel.org/pub/scm/fs/fsverity/linux:
  fscrypt: support decrypting data from large folios
  fsverity: support verifying data from large folios
  fsverity.rst: update git repo URL for fsverity-utils
  ext4: allow verity with fs block size < PAGE_SIZE
  fs/buffer.c: support fsverity in block_read_full_folio()
  f2fs: simplify f2fs_readpage_limit()
  ext4: simplify ext4_readpage_limit()
  fsverity: support enabling with tree block size < PAGE_SIZE
  fsverity: support verification with tree block size < PAGE_SIZE
  fsverity: replace fsverity_hash_page() with fsverity_hash_block()
  fsverity: use EFBIG for file too large to enable verity
  fsverity: store log2(digest_size) precomputed
  fsverity: simplify Merkle tree readahead size calculation
  fsverity: use unsigned long for level_start
  fsverity: remove debug messages and CONFIG_FS_VERITY_DEBUG
  fsverity: pass pos and size to ->write_merkle_tree_block
  fsverity: optimize fsverity_cleanup_inode() on non-verity files
  fsverity: optimize fsverity_prepare_setattr() on non-verity files
  fsverity: optimize fsverity_file_open() on non-verity files

1 files changed, 60 insertions, 12 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index d9c6d1fbb6dd..623e77d6ef77 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -48,6 +48,7 @@
 #include <linux/sched/mm.h>
 #include <trace/events/block.h>
 #include <linux/fscrypt.h>
+#include <linux/fsverity.h>
 
 #include "internal.h"
 
@@ -295,20 +296,53 @@ still_busy:
 	return;
 }
 
-struct decrypt_bh_ctx {
+struct postprocess_bh_ctx {
 	struct work_struct work;
 	struct buffer_head *bh;
 };
 
+static void verify_bh(struct work_struct *work)
+{
+	struct postprocess_bh_ctx *ctx =
+		container_of(work, struct postprocess_bh_ctx, work);
+	struct buffer_head *bh = ctx->bh;
+	bool valid;
+
+	valid = fsverity_verify_blocks(page_folio(bh->b_page), bh->b_size,
+				       bh_offset(bh));
+	end_buffer_async_read(bh, valid);
+	kfree(ctx);
+}
+
+static bool need_fsverity(struct buffer_head *bh)
+{
+	struct page *page = bh->b_page;
+	struct inode *inode = page->mapping->host;
+
+	return fsverity_active(inode) &&
+		/* needed by ext4 */
+		page->index < DIV_ROUND_UP(inode->i_size, PAGE_SIZE);
+}
+
 static void decrypt_bh(struct work_struct *work)
 {
-	struct decrypt_bh_ctx *ctx =
-		container_of(work, struct decrypt_bh_ctx, work);
+	struct postprocess_bh_ctx *ctx =
+		container_of(work, struct postprocess_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));
+	err = fscrypt_decrypt_pagecache_blocks(page_folio(bh->b_page),
+					       bh->b_size, bh_offset(bh));
+	if (err == 0 && need_fsverity(bh)) {
+		/*
+		 * We use different work queues for decryption and for verity
+		 * because verity may require reading metadata pages that need
+		 * decryption, and we shouldn't recurse to the same workqueue.
+		 */
+		INIT_WORK(&ctx->work, verify_bh);
+		fsverity_enqueue_verify_work(&ctx->work);
+		return;
+	}
 	end_buffer_async_read(bh, err == 0);
 	kfree(ctx);
 }
@@ -319,15 +353,24 @@ static void decrypt_bh(struct work_struct *work)
  */
 static void end_buffer_async_read_io(struct buffer_head *bh, int uptodate)
 {
-	/* Decrypt if needed */
-	if (uptodate &&
-	    fscrypt_inode_uses_fs_layer_crypto(bh->b_page->mapping->host)) {
-		struct decrypt_bh_ctx *ctx = kmalloc(sizeof(*ctx), GFP_ATOMIC);
+	struct inode *inode = bh->b_page->mapping->host;
+	bool decrypt = fscrypt_inode_uses_fs_layer_crypto(inode);
+	bool verify = need_fsverity(bh);
+
+	/* Decrypt (with fscrypt) and/or verify (with fsverity) if needed. */
+	if (uptodate && (decrypt || verify)) {
+		struct postprocess_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);
+			if (decrypt) {
+				INIT_WORK(&ctx->work, decrypt_bh);
+				fscrypt_enqueue_decrypt_work(&ctx->work);
+			} else {
+				INIT_WORK(&ctx->work, verify_bh);
+				fsverity_enqueue_verify_work(&ctx->work);
+			}
 			return;
 		}
 		uptodate = 0;
@@ -2245,6 +2288,11 @@ int block_read_full_folio(struct folio *folio, get_block_t *get_block)
 	int nr, i;
 	int fully_mapped = 1;
 	bool page_error = false;
+	loff_t limit = i_size_read(inode);
+
+	/* This is needed for ext4. */
+	if (IS_ENABLED(CONFIG_FS_VERITY) && IS_VERITY(inode))
+		limit = inode->i_sb->s_maxbytes;
 
 	VM_BUG_ON_FOLIO(folio_test_large(folio), folio);
 
@@ -2253,7 +2301,7 @@ int block_read_full_folio(struct folio *folio, get_block_t *get_block)
 	bbits = block_size_bits(blocksize);
 
 	iblock = (sector_t)folio->index << (PAGE_SHIFT - bbits);
-	lblock = (i_size_read(inode)+blocksize-1) >> bbits;
+	lblock = (limit+blocksize-1) >> bbits;
 	bh = head;
 	nr = 0;
 	i = 0;