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ext4: clean up ext4_match() and callers 

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>
hifive-unleashed-5.1
Eric Biggers 2017-04-24 10:00:13 -07:00 committed by Theodore Ts'o
parent 1f73d49177
commit d9b9f8d5a8
1 changed files with 25 additions and 56 deletions
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81
fs/ext4/namei.c
View File

@ -1237,18 +1237,17 @@ 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)
{
struct fscrypt_name f;
if (!de->inode)
return 0;
return false;
f.usr_fname = fname->usr_fname;
f.disk_name = fname->disk_name;
@ -1269,48 +1268,31 @@ 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,
@ -1814,24 +1796,15 @@ 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)
@ -1839,15 +1812,11 @@ 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,