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ext4 crypto: simplify and speed up filename encryption

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Avoid using SHA-1 when calculating the user-visible filename when the
encryption key is available, and avoid decrypting lots of filenames
when searching for a directory entry in a directory block.

Change-Id: If4655f144784978ba0305b597bfa1c8d7bb69e63
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o
2015-05-01 16:56:45 -04:00
parent 6ddb244784
commit 5de0b4d0cd
5 changed files with 154 additions and 209 deletions
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72
fs/ext4/namei.c
View File

@@ -640,7 +640,7 @@ static struct stats dx_show_leaf(struct inode *dir,
ext4_put_fname_crypto_ctx(&ctx);
ctx = NULL;
}
res = ext4_fname_disk_to_usr(ctx, de,
res = ext4_fname_disk_to_usr(ctx, NULL, de,
&fname_crypto_str);
if (res < 0) {
printk(KERN_WARNING "Error "
@@ -653,15 +653,8 @@ static struct stats dx_show_leaf(struct inode *dir,
name = fname_crypto_str.name;
len = fname_crypto_str.len;
}
res = ext4_fname_disk_to_hash(ctx, de,
&h);
if (res < 0) {
printk(KERN_WARNING "Error "
"converting filename "
"from disk to htree"
"\n");
h.hash = 0xDEADBEEF;
}
ext4fs_dirhash(de->name, de->name_len,
&h);
printk("%*.s:(E)%x.%u ", len, name,
h.hash, (unsigned) ((char *) de
- base));
@@ -1008,15 +1001,7 @@ static int htree_dirblock_to_tree(struct file *dir_file,
/* silently ignore the rest of the block */
break;
}
#ifdef CONFIG_EXT4_FS_ENCRYPTION
err = ext4_fname_disk_to_hash(ctx, de, hinfo);
if (err < 0) {
count = err;
goto errout;
}
#else
ext4fs_dirhash(de->name, de->name_len, hinfo);
#endif
if ((hinfo->hash < start_hash) ||
((hinfo->hash == start_hash) &&
(hinfo->minor_hash < start_minor_hash)))
@@ -1032,7 +1017,7 @@ static int htree_dirblock_to_tree(struct file *dir_file,
&tmp_str);
} else {
/* Directory is encrypted */
err = ext4_fname_disk_to_usr(ctx, de,
err = ext4_fname_disk_to_usr(ctx, hinfo, de,
&fname_crypto_str);
if (err < 0) {
count = err;
@@ -1193,26 +1178,10 @@ static int dx_make_map(struct inode *dir, struct ext4_dir_entry_2 *de,
int count = 0;
char *base = (char *) de;
struct dx_hash_info h = *hinfo;
#ifdef CONFIG_EXT4_FS_ENCRYPTION
struct ext4_fname_crypto_ctx *ctx = NULL;
int err;
ctx = ext4_get_fname_crypto_ctx(dir, EXT4_NAME_LEN);
if (IS_ERR(ctx))
return PTR_ERR(ctx);
#endif
while ((char *) de < base + blocksize) {
if (de->name_len && de->inode) {
#ifdef CONFIG_EXT4_FS_ENCRYPTION
err = ext4_fname_disk_to_hash(ctx, de, &h);
if (err < 0) {
ext4_put_fname_crypto_ctx(&ctx);
return err;
}
#else
ext4fs_dirhash(de->name, de->name_len, &h);
#endif
map_tail--;
map_tail->hash = h.hash;
map_tail->offs = ((char *) de - base)>>2;
@@ -1223,9 +1192,6 @@ static int dx_make_map(struct inode *dir, struct ext4_dir_entry_2 *de,
/* XXX: do we need to check rec_len == 0 case? -Chris */
de = ext4_next_entry(de, blocksize);
}
#ifdef CONFIG_EXT4_FS_ENCRYPTION
ext4_put_fname_crypto_ctx(&ctx);
#endif
return count;
}
@@ -1287,16 +1253,8 @@ static inline int ext4_match(struct ext4_fname_crypto_ctx *ctx,
return 0;
#ifdef CONFIG_EXT4_FS_ENCRYPTION
if (ctx) {
/* Directory is encrypted */
res = ext4_fname_disk_to_usr(ctx, de, fname_crypto_str);
if (res < 0)
return res;
if (len != res)
return 0;
res = memcmp(name, fname_crypto_str->name, len);
return (res == 0) ? 1 : 0;
}
if (ctx)
return ext4_fname_match(ctx, fname_crypto_str, len, name, de);
#endif
if (len != de->name_len)
return 0;
@@ -1324,16 +1282,6 @@ int search_dir(struct buffer_head *bh, char *search_buf, int buf_size,
if (IS_ERR(ctx))
return -1;
if (ctx != NULL) {
/* Allocate buffer to hold maximum name length */
res = ext4_fname_crypto_alloc_buffer(ctx, EXT4_NAME_LEN,
&fname_crypto_str);
if (res < 0) {
ext4_put_fname_crypto_ctx(&ctx);
return -1;
}
}
de = (struct ext4_dir_entry_2 *)search_buf;
dlimit = search_buf + buf_size;
while ((char *) de < dlimit) {
@@ -1872,14 +1820,6 @@ int ext4_find_dest_de(struct inode *dir, struct inode *inode,
return res;
}
reclen = EXT4_DIR_REC_LEN(res);
/* Allocate buffer to hold maximum name length */
res = ext4_fname_crypto_alloc_buffer(ctx, EXT4_NAME_LEN,
&fname_crypto_str);
if (res < 0) {
ext4_put_fname_crypto_ctx(&ctx);
return -1;
}
}
de = (struct ext4_dir_entry_2 *)buf;