[PATCH 4.9 16/39] ext4: clean up ext4_match() and callers

Greg Kroah-Hartman
2020-08-24T09:28:41Z

From: Eric Biggers <ebiggers@google.com>

[ Upstream commit d9b9f8d5a88cb7881d9f1c2b7e9de9a3fe1dc9e2 ]

When ext4 encryption was originally merged, we were encrypting the
user-specified filename in ext4_match(), introducing a lot of additional
complexity into ext4_match() and its callers. This has since been
changed to encrypt the filename earlier, so we can remove the gunk
that's no longer needed. This more or less reverts ext4_search_dir()
and ext4_find_dest_de() to the way they were in the v4.0 kernel.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/ext4/namei.c | 81 +++++++++++++++----------------------------------
1 file changed, 25 insertions(+), 56 deletions(-)

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 6225ce9f1884c..dd42d533d2816 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1251,19 +1251,18 @@ static void dx_insert_block(struct dx_frame *frame, u32 hash, ext4_lblk_t block)
}

/*
- * NOTE! unlike strncmp, ext4_match returns 1 for success, 0 for failure.
+ * Test whether a directory entry matches the filename being searched for.
*
- * `len <= EXT4_NAME_LEN' is guaranteed by caller.
- * `de != NULL' is guaranteed by caller.
+ * Return: %true if the directory entry matches, otherwise %false.
*/
-static inline int ext4_match(struct ext4_filename *fname,
- struct ext4_dir_entry_2 *de)
+static inline bool ext4_match(const struct ext4_filename *fname,
+ const struct ext4_dir_entry_2 *de)
{
const void *name = fname_name(fname);
u32 len = fname_len(fname);

if (!de->inode)
- return 0;
+ return false;

#ifdef CONFIG_EXT4_FS_ENCRYPTION
if (unlikely(!name)) {
@@ -1295,48 +1294,31 @@ int ext4_search_dir(struct buffer_head *bh, char *search_buf, int buf_size,
struct ext4_dir_entry_2 * de;
char * dlimit;
int de_len;
- int res;

de = (struct ext4_dir_entry_2 *)search_buf;
dlimit = search_buf + buf_size;
while ((char *) de < dlimit) {
/* this code is executed quadratically often */
/* do minimal checking `by hand' */
- if ((char *) de + de->name_len <= dlimit) {
- res = ext4_match(fname, de);
- if (res < 0) {
- res = -1;
- goto return_result;
- }
- if (res > 0) {
- /* found a match - just to be sure, do
- * a full check */
- if (ext4_check_dir_entry(dir, NULL, de, bh,
- bh->b_data,
- bh->b_size, offset)) {
- res = -1;
- goto return_result;
- }
- *res_dir = de;
- res = 1;
- goto return_result;
- }
-
+ if ((char *) de + de->name_len <= dlimit &&
+ ext4_match(fname, de)) {
+ /* found a match - just to be sure, do
+ * a full check */
+ if (ext4_check_dir_entry(dir, NULL, de, bh, bh->b_data,
+ bh->b_size, offset))
+ return -1;
+ *res_dir = de;
+ return 1;
}
/* prevent looping on a bad block */
de_len = ext4_rec_len_from_disk(de->rec_len,
dir->i_sb->s_blocksize);
- if (de_len <= 0) {
- res = -1;
- goto return_result;
- }
+ if (de_len <= 0)
+ return -1;
offset += de_len;
de = (struct ext4_dir_entry_2 *) ((char *) de + de_len);
}
-
- res = 0;
-return_result:
- return res;
+ return 0;
}

static int is_dx_internal_node(struct inode *dir, ext4_lblk_t block,
@@ -1853,24 +1835,15 @@ int ext4_find_dest_de(struct inode *dir, struct inode *inode,
int nlen, rlen;
unsigned int offset = 0;
char *top;
- int res;

de = (struct ext4_dir_entry_2 *)buf;
top = buf + buf_size - reclen;
while ((char *) de <= top) {
if (ext4_check_dir_entry(dir, NULL, de, bh,
- buf, buf_size, offset)) {
- res = -EFSCORRUPTED;
- goto return_result;
- }
- /* Provide crypto context and crypto buffer to ext4 match */
- res = ext4_match(fname, de);
- if (res < 0)
- goto return_result;
- if (res > 0) {
- res = -EEXIST;
- goto return_result;
- }
+ buf, buf_size, offset))
+ return -EFSCORRUPTED;
+ if (ext4_match(fname, de))
+ return -EEXIST;
nlen = EXT4_DIR_REC_LEN(de->name_len);
rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
if ((de->inode ? rlen - nlen : rlen) >= reclen)
@@ -1878,15 +1851,11 @@ int ext4_find_dest_de(struct inode *dir, struct inode *inode,
de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
offset += rlen;
}
-
if ((char *) de > top)
- res = -ENOSPC;
- else {
- *dest_de = de;
- res = 0;
- }
-return_result:
- return res;
+ return -ENOSPC;
+
+ *dest_de = de;
+ return 0;
}

int ext4_insert_dentry(struct inode *dir,
--
2.25.1