[PATCH 5.10 0/2] Selected ext4 fast-commit fixes for 5.10-stable

[PATCH 5.10 0/2] Selected ext4 fast-commit fixes for 5.10-stable

[Eric Biggers]

The recent ext4 fast-commit fixes with 'Cc stable' didn't apply to 5.10
due to conflicts.  Since the fast-commit support in 5.10 is rudimentary
and hard to backport fixes too, this series backports the two most
important fixes only.  Please apply to 5.10-stable.

Eric Biggers (2):
  ext4: disable fast-commit of encrypted dir operations
  ext4: don't set up encryption key during jbd2 transaction

 fs/ext4/ext4.h              |  4 ++--
 fs/ext4/fast_commit.c       | 42 +++++++++++++++++++++--------------
 fs/ext4/fast_commit.h       |  1 +
 fs/ext4/namei.c             | 44 ++++++++++++++++++++-----------------
 include/trace/events/ext4.h |  7 ++++--
 5 files changed, 57 insertions(+), 41 deletions(-)

-- 
2.39.0

[PATCH 5.10 1/2] ext4: disable fast-commit of encrypted dir operations

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

commit 0fbcb5251fc81b58969b272c4fb7374a7b922e3e upstream.

fast-commit of create, link, and unlink operations in encrypted
directories is completely broken because the unencrypted filenames are
being written to the fast-commit journal instead of the encrypted
filenames.  These operations can't be replayed, as encryption keys
aren't present at journal replay time.  It is also an information leak.

Until if/when we can get this working properly, make encrypted directory
operations ineligible for fast-commit.

Note that fast-commit operations on encrypted regular files continue to
be allowed, as they seem to work.

Fixes: aa75f4d3daae ("ext4: main fast-commit commit path")
Cc: <stable@vger.kernel.org> # v5.10+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20221106224841.279231-2-ebiggers@kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/ext4/fast_commit.c       | 40 ++++++++++++++++++++++---------------
 fs/ext4/fast_commit.h       |  1 +
 include/trace/events/ext4.h |  7 +++++--
 3 files changed, 30 insertions(+), 18 deletions(-)

diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c
index 41dcf21558c4e..e26020598e194 100644
--- a/fs/ext4/fast_commit.c
+++ b/fs/ext4/fast_commit.c
@@ -371,25 +371,33 @@ static int __track_dentry_update(struct inode *inode, void *arg, bool update)
 	struct __track_dentry_update_args *dentry_update =
 		(struct __track_dentry_update_args *)arg;
 	struct dentry *dentry = dentry_update->dentry;
-	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	struct inode *dir = dentry->d_parent->d_inode;
+	struct super_block *sb = inode->i_sb;
+	struct ext4_sb_info *sbi = EXT4_SB(sb);
 
 	mutex_unlock(&ei->i_fc_lock);
+
+	if (IS_ENCRYPTED(dir)) {
+		ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_ENCRYPTED_FILENAME);
+		mutex_lock(&ei->i_fc_lock);
+		return -EOPNOTSUPP;
+	}
+
 	node = kmem_cache_alloc(ext4_fc_dentry_cachep, GFP_NOFS);
 	if (!node) {
-		ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_NOMEM);
+		ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_NOMEM);
 		mutex_lock(&ei->i_fc_lock);
 		return -ENOMEM;
 	}
 
 	node->fcd_op = dentry_update->op;
-	node->fcd_parent = dentry->d_parent->d_inode->i_ino;
+	node->fcd_parent = dir->i_ino;
 	node->fcd_ino = inode->i_ino;
 	if (dentry->d_name.len > DNAME_INLINE_LEN) {
 		node->fcd_name.name = kmalloc(dentry->d_name.len, GFP_NOFS);
 		if (!node->fcd_name.name) {
 			kmem_cache_free(ext4_fc_dentry_cachep, node);
-			ext4_fc_mark_ineligible(inode->i_sb,
-				EXT4_FC_REASON_NOMEM);
+			ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_NOMEM);
 			mutex_lock(&ei->i_fc_lock);
 			return -ENOMEM;
 		}
@@ -2137,17 +2145,17 @@ void ext4_fc_init(struct super_block *sb, journal_t *journal)
 	journal->j_fc_cleanup_callback = ext4_fc_cleanup;
 }
 
-static const char *fc_ineligible_reasons[] = {
-	"Extended attributes changed",
-	"Cross rename",
-	"Journal flag changed",
-	"Insufficient memory",
-	"Swap boot",
-	"Resize",
-	"Dir renamed",
-	"Falloc range op",
-	"Data journalling",
-	"FC Commit Failed"
+static const char * const fc_ineligible_reasons[] = {
+	[EXT4_FC_REASON_XATTR] = "Extended attributes changed",
+	[EXT4_FC_REASON_CROSS_RENAME] = "Cross rename",
+	[EXT4_FC_REASON_JOURNAL_FLAG_CHANGE] = "Journal flag changed",
+	[EXT4_FC_REASON_NOMEM] = "Insufficient memory",
+	[EXT4_FC_REASON_SWAP_BOOT] = "Swap boot",
+	[EXT4_FC_REASON_RESIZE] = "Resize",
+	[EXT4_FC_REASON_RENAME_DIR] = "Dir renamed",
+	[EXT4_FC_REASON_FALLOC_RANGE] = "Falloc range op",
+	[EXT4_FC_REASON_INODE_JOURNAL_DATA] = "Data journalling",
+	[EXT4_FC_REASON_ENCRYPTED_FILENAME] = "Encrypted filename",
 };
 
 int ext4_fc_info_show(struct seq_file *seq, void *v)
diff --git a/fs/ext4/fast_commit.h b/fs/ext4/fast_commit.h
index d8d0998a5c163..4a5f96a9c9d72 100644
--- a/fs/ext4/fast_commit.h
+++ b/fs/ext4/fast_commit.h
@@ -104,6 +104,7 @@ enum {
 	EXT4_FC_REASON_FALLOC_RANGE,
 	EXT4_FC_REASON_INODE_JOURNAL_DATA,
 	EXT4_FC_COMMIT_FAILED,
+	EXT4_FC_REASON_ENCRYPTED_FILENAME,
 	EXT4_FC_REASON_MAX
 };
 
diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h
index 4973265655a7f..1a91d5789df3b 100644
--- a/include/trace/events/ext4.h
+++ b/include/trace/events/ext4.h
@@ -104,6 +104,7 @@ TRACE_DEFINE_ENUM(EXT4_FC_REASON_RESIZE);
 TRACE_DEFINE_ENUM(EXT4_FC_REASON_RENAME_DIR);
 TRACE_DEFINE_ENUM(EXT4_FC_REASON_FALLOC_RANGE);
 TRACE_DEFINE_ENUM(EXT4_FC_REASON_INODE_JOURNAL_DATA);
+TRACE_DEFINE_ENUM(EXT4_FC_REASON_ENCRYPTED_FILENAME);
 TRACE_DEFINE_ENUM(EXT4_FC_REASON_MAX);
 
 #define show_fc_reason(reason)						\
@@ -116,7 +117,8 @@ TRACE_DEFINE_ENUM(EXT4_FC_REASON_MAX);
 		{ EXT4_FC_REASON_RESIZE,	"RESIZE"},		\
 		{ EXT4_FC_REASON_RENAME_DIR,	"RENAME_DIR"},		\
 		{ EXT4_FC_REASON_FALLOC_RANGE,	"FALLOC_RANGE"},	\
-		{ EXT4_FC_REASON_INODE_JOURNAL_DATA,	"INODE_JOURNAL_DATA"})
+		{ EXT4_FC_REASON_INODE_JOURNAL_DATA,	"INODE_JOURNAL_DATA"}, \
+		{ EXT4_FC_REASON_ENCRYPTED_FILENAME,	"ENCRYPTED_FILENAME"})
 
 TRACE_EVENT(ext4_other_inode_update_time,
 	TP_PROTO(struct inode *inode, ino_t orig_ino),
@@ -2940,7 +2942,7 @@ TRACE_EVENT(ext4_fc_stats,
 	),
 
 	TP_printk("dev %d,%d fc ineligible reasons:\n"
-		  "%s:%u, %s:%u, %s:%u, %s:%u, %s:%u, %s:%u, %s:%u, %s:%u, %s:%u "
+		  "%s:%u, %s:%u, %s:%u, %s:%u, %s:%u, %s:%u, %s:%u, %s:%u, %s:%u, %s:%u"
 		  "num_commits:%lu, ineligible: %lu, numblks: %lu",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
 		  FC_REASON_NAME_STAT(EXT4_FC_REASON_XATTR),
@@ -2952,6 +2954,7 @@ TRACE_EVENT(ext4_fc_stats,
 		  FC_REASON_NAME_STAT(EXT4_FC_REASON_RENAME_DIR),
 		  FC_REASON_NAME_STAT(EXT4_FC_REASON_FALLOC_RANGE),
 		  FC_REASON_NAME_STAT(EXT4_FC_REASON_INODE_JOURNAL_DATA),
+		  FC_REASON_NAME_STAT(EXT4_FC_REASON_ENCRYPTED_FILENAME),
 		  __entry->fc_commits, __entry->fc_ineligible_commits,
 		  __entry->fc_numblks)
 );
-- 
2.39.0

[PATCH 5.10 2/2] ext4: don't set up encryption key during jbd2 transaction

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

commit 4c0d5778385cb3618ff26a561ce41de2b7d9de70 upstream.

Commit a80f7fcf1867 ("ext4: fixup ext4_fc_track_* functions' signature")
extended the scope of the transaction in ext4_unlink() too far, making
it include the call to ext4_find_entry().  However, ext4_find_entry()
can deadlock when called from within a transaction because it may need
to set up the directory's encryption key.

Fix this by restoring the transaction to its original scope.

Reported-by: syzbot+1a748d0007eeac3ab079@syzkaller.appspotmail.com
Fixes: a80f7fcf1867 ("ext4: fixup ext4_fc_track_* functions' signature")
Cc: <stable@vger.kernel.org> # v5.10+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20221106224841.279231-3-ebiggers@kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/ext4/ext4.h        |  4 ++--
 fs/ext4/fast_commit.c |  2 +-
 fs/ext4/namei.c       | 44 +++++++++++++++++++++++--------------------
 3 files changed, 27 insertions(+), 23 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index fb9c9e1813bc5..81dc61f1c557f 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -3486,8 +3486,8 @@ extern int ext4_handle_dirty_dirblock(handle_t *handle, struct inode *inode,
 extern int ext4_ci_compare(const struct inode *parent,
 			   const struct qstr *fname,
 			   const struct qstr *entry, bool quick);
-extern int __ext4_unlink(handle_t *handle, struct inode *dir, const struct qstr *d_name,
-			 struct inode *inode);
+extern int __ext4_unlink(struct inode *dir, const struct qstr *d_name,
+			 struct inode *inode, struct dentry *dentry);
 extern int __ext4_link(struct inode *dir, struct inode *inode,
 		       struct dentry *dentry);
 
diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c
index e26020598e194..be96f5ccc55dd 100644
--- a/fs/ext4/fast_commit.c
+++ b/fs/ext4/fast_commit.c
@@ -1295,7 +1295,7 @@ static int ext4_fc_replay_unlink(struct super_block *sb, struct ext4_fc_tl *tl,
 		return 0;
 	}
 
-	ret = __ext4_unlink(NULL, old_parent, &entry, inode);
+	ret = __ext4_unlink(old_parent, &entry, inode, NULL);
 	/* -ENOENT ok coz it might not exist anymore. */
 	if (ret == -ENOENT)
 		ret = 0;
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index c17d5f399f9ea..e296b3587bb38 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -3244,14 +3244,20 @@ static int ext4_rmdir(struct inode *dir, struct dentry *dentry)
 	return retval;
 }
 
-int __ext4_unlink(handle_t *handle, struct inode *dir, const struct qstr *d_name,
-		  struct inode *inode)
+int __ext4_unlink(struct inode *dir, const struct qstr *d_name,
+		  struct inode *inode,
+		  struct dentry *dentry /* NULL during fast_commit recovery */)
 {
 	int retval = -ENOENT;
 	struct buffer_head *bh;
 	struct ext4_dir_entry_2 *de;
+	handle_t *handle;
 	int skip_remove_dentry = 0;
 
+	/*
+	 * Keep this outside the transaction; it may have to set up the
+	 * directory's encryption key, which isn't GFP_NOFS-safe.
+	 */
 	bh = ext4_find_entry(dir, d_name, &de, NULL);
 	if (IS_ERR(bh))
 		return PTR_ERR(bh);
@@ -3268,7 +3274,14 @@ int __ext4_unlink(handle_t *handle, struct inode *dir, const struct qstr *d_name
 		if (EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
 			skip_remove_dentry = 1;
 		else
-			goto out;
+			goto out_bh;
+	}
+
+	handle = ext4_journal_start(dir, EXT4_HT_DIR,
+				    EXT4_DATA_TRANS_BLOCKS(dir->i_sb));
+	if (IS_ERR(handle)) {
+		retval = PTR_ERR(handle);
+		goto out_bh;
 	}
 
 	if (IS_DIRSYNC(dir))
@@ -3277,12 +3290,12 @@ int __ext4_unlink(handle_t *handle, struct inode *dir, const struct qstr *d_name
 	if (!skip_remove_dentry) {
 		retval = ext4_delete_entry(handle, dir, de, bh);
 		if (retval)
-			goto out;
+			goto out_handle;
 		dir->i_ctime = dir->i_mtime = current_time(dir);
 		ext4_update_dx_flag(dir);
 		retval = ext4_mark_inode_dirty(handle, dir);
 		if (retval)
-			goto out;
+			goto out_handle;
 	} else {
 		retval = 0;
 	}
@@ -3295,15 +3308,17 @@ int __ext4_unlink(handle_t *handle, struct inode *dir, const struct qstr *d_name
 		ext4_orphan_add(handle, inode);
 	inode->i_ctime = current_time(inode);
 	retval = ext4_mark_inode_dirty(handle, inode);
-
-out:
+	if (dentry && !retval)
+		ext4_fc_track_unlink(handle, dentry);
+out_handle:
+	ext4_journal_stop(handle);
+out_bh:
 	brelse(bh);
 	return retval;
 }
 
 static int ext4_unlink(struct inode *dir, struct dentry *dentry)
 {
-	handle_t *handle;
 	int retval;
 
 	if (unlikely(ext4_forced_shutdown(EXT4_SB(dir->i_sb))))
@@ -3321,16 +3336,7 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
 	if (retval)
 		goto out_trace;
 
-	handle = ext4_journal_start(dir, EXT4_HT_DIR,
-				    EXT4_DATA_TRANS_BLOCKS(dir->i_sb));
-	if (IS_ERR(handle)) {
-		retval = PTR_ERR(handle);
-		goto out_trace;
-	}
-
-	retval = __ext4_unlink(handle, dir, &dentry->d_name, d_inode(dentry));
-	if (!retval)
-		ext4_fc_track_unlink(handle, dentry);
+	retval = __ext4_unlink(dir, &dentry->d_name, d_inode(dentry), dentry);
 #ifdef CONFIG_UNICODE
 	/* VFS negative dentries are incompatible with Encoding and
 	 * Case-insensitiveness. Eventually we'll want avoid
@@ -3341,8 +3347,6 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
 	if (IS_CASEFOLDED(dir))
 		d_invalidate(dentry);
 #endif
-	if (handle)
-		ext4_journal_stop(handle);
 
 out_trace:
 	trace_ext4_unlink_exit(dentry, retval);
-- 
2.39.0

Re: [PATCH 5.10 0/2] Selected ext4 fast-commit fixes for 5.10-stable

[Greg KH]

On Sat, Jan 07, 2023 at 12:37:11PM -0800, Eric Biggers wrote:
> The recent ext4 fast-commit fixes with 'Cc stable' didn't apply to 5.10
> due to conflicts.  Since the fast-commit support in 5.10 is rudimentary
> and hard to backport fixes too, this series backports the two most
> important fixes only.  Please apply to 5.10-stable.
> 
> Eric Biggers (2):
>   ext4: disable fast-commit of encrypted dir operations
>   ext4: don't set up encryption key during jbd2 transaction
> 
>  fs/ext4/ext4.h              |  4 ++--
>  fs/ext4/fast_commit.c       | 42 +++++++++++++++++++++--------------
>  fs/ext4/fast_commit.h       |  1 +
>  fs/ext4/namei.c             | 44 ++++++++++++++++++++-----------------
>  include/trace/events/ext4.h |  7 ++++--
>  5 files changed, 57 insertions(+), 41 deletions(-)
> 
> -- 
> 2.39.0
> 

All now queued up, thanks.

greg k-h