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ext4 crypto: optimize filename encryption
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Encrypt the filename as soon it is passed in by the user.  This avoids
our needing to encrypt the filename 2 or 3 times while in the process
of creating a filename.

Similarly, when looking up a directory entry, encrypt the filename
early, or if the encryption key is not available, base-64 decode the
file syystem so that the hash value and the last 16 bytes of the
encrypted filename is available in the new struct ext4_filename data
structure.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Theodore Ts'o committed May 18, 2015
1 parent e260818 commit 5b643f9
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Showing 4 changed files with 230 additions and 313 deletions.
155 changes: 64 additions & 91 deletions fs/ext4/crypto_fname.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -611,109 +611,82 @@ int ext4_fname_usr_to_disk(struct ext4_fname_crypto_ctx *ctx,
return -EACCES;
}

/*
* Calculate the htree hash from a filename from user space
*/
int ext4_fname_usr_to_hash(struct ext4_fname_crypto_ctx *ctx,
const struct qstr *iname,
struct dx_hash_info *hinfo)
int ext4_fname_setup_filename(struct inode *dir, const struct qstr *iname,
int lookup, struct ext4_filename *fname)
{
struct ext4_str tmp;
int ret = 0;
char buf[EXT4_FNAME_CRYPTO_DIGEST_SIZE+1];
struct ext4_fname_crypto_ctx *ctx;
int ret = 0, bigname = 0;

memset(fname, 0, sizeof(struct ext4_filename));
fname->usr_fname = iname;

if (!ctx ||
ctx = ext4_get_fname_crypto_ctx(dir, EXT4_NAME_LEN);
if (IS_ERR(ctx))
return PTR_ERR(ctx);
if ((ctx == NULL) ||
((iname->name[0] == '.') &&
((iname->len == 1) ||
((iname->name[1] == '.') && (iname->len == 2))))) {
ext4fs_dirhash(iname->name, iname->len, hinfo);
return 0;
fname->disk_name.name = (unsigned char *) iname->name;
fname->disk_name.len = iname->len;
goto out;
}

if (!ctx->has_valid_key && iname->name[0] == '_') {
if (iname->len != 33)
return -ENOENT;
ret = digest_decode(iname->name+1, iname->len, buf);
if (ret != 24)
return -ENOENT;
memcpy(&hinfo->hash, buf, 4);
memcpy(&hinfo->minor_hash, buf + 4, 4);
return 0;
if (ctx->has_valid_key) {
ret = ext4_fname_crypto_alloc_buffer(ctx, iname->len,
&fname->crypto_buf);
if (ret < 0)
goto out;
ret = ext4_fname_encrypt(ctx, iname, &fname->crypto_buf);
if (ret < 0)
goto out;
fname->disk_name.name = fname->crypto_buf.name;
fname->disk_name.len = fname->crypto_buf.len;
ret = 0;
goto out;
}

if (!ctx->has_valid_key && iname->name[0] != '_') {
if (iname->len > 43)
return -ENOENT;
ret = digest_decode(iname->name, iname->len, buf);
ext4fs_dirhash(buf, ret, hinfo);
return 0;
if (!lookup) {
ret = -EACCES;
goto out;
}

/* First encrypt the plaintext name */
ret = ext4_fname_crypto_alloc_buffer(ctx, iname->len, &tmp);
if (ret < 0)
return ret;

ret = ext4_fname_encrypt(ctx, iname, &tmp);
if (ret >= 0) {
ext4fs_dirhash(tmp.name, tmp.len, hinfo);
ret = 0;
/* We don't have the key and we are doing a lookup; decode the
* user-supplied name
*/
if (iname->name[0] == '_')
bigname = 1;
if ((bigname && (iname->len != 33)) ||
(!bigname && (iname->len > 43))) {
ret = -ENOENT;
}

ext4_fname_crypto_free_buffer(&tmp);
fname->crypto_buf.name = kmalloc(32, GFP_KERNEL);
if (fname->crypto_buf.name == NULL) {
ret = -ENOMEM;
goto out;
}
ret = digest_decode(iname->name + bigname, iname->len - bigname,
fname->crypto_buf.name);
if (ret < 0) {
ret = -ENOENT;
goto out;
}
fname->crypto_buf.len = ret;
if (bigname) {
memcpy(&fname->hinfo.hash, fname->crypto_buf.name, 4);
memcpy(&fname->hinfo.minor_hash, fname->crypto_buf.name + 4, 4);
} else {
fname->disk_name.name = fname->crypto_buf.name;
fname->disk_name.len = fname->crypto_buf.len;
}
ret = 0;
out:
ext4_put_fname_crypto_ctx(&ctx);
return ret;
}

int ext4_fname_match(struct ext4_fname_crypto_ctx *ctx, struct ext4_str *cstr,
int len, const char * const name,
struct ext4_dir_entry_2 *de)
void ext4_fname_free_filename(struct ext4_filename *fname)
{
int ret = -ENOENT;
int bigname = (*name == '_');

if (ctx->has_valid_key) {
if (cstr->name == NULL) {
struct qstr istr;

ret = ext4_fname_crypto_alloc_buffer(ctx, len, cstr);
if (ret < 0)
goto errout;
istr.name = name;
istr.len = len;
ret = ext4_fname_encrypt(ctx, &istr, cstr);
if (ret < 0)
goto errout;
}
} else {
if (cstr->name == NULL) {
cstr->name = kmalloc(32, GFP_KERNEL);
if (cstr->name == NULL)
return -ENOMEM;
if ((bigname && (len != 33)) ||
(!bigname && (len > 43)))
goto errout;
ret = digest_decode(name+bigname, len-bigname,
cstr->name);
if (ret < 0) {
ret = -ENOENT;
goto errout;
}
cstr->len = ret;
}
if (bigname) {
if (de->name_len < 16)
return 0;
ret = memcmp(de->name + de->name_len - 16,
cstr->name + 8, 16);
return (ret == 0) ? 1 : 0;
}
}
if (de->name_len != cstr->len)
return 0;
ret = memcmp(de->name, cstr->name, cstr->len);
return (ret == 0) ? 1 : 0;
errout:
kfree(cstr->name);
cstr->name = NULL;
return ret;
kfree(fname->crypto_buf.name);
fname->crypto_buf.name = NULL;
fname->usr_fname = NULL;
fname->disk_name.name = NULL;
}
63 changes: 41 additions & 22 deletions fs/ext4/ext4.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1838,6 +1838,17 @@ struct dx_hash_info
*/
#define HASH_NB_ALWAYS 1

struct ext4_filename {
const struct qstr *usr_fname;
struct ext4_str disk_name;
struct dx_hash_info hinfo;
#ifdef CONFIG_EXT4_FS_ENCRYPTION
struct ext4_str crypto_buf;
#endif
};

#define fname_name(p) ((p)->disk_name.name)
#define fname_len(p) ((p)->disk_name.len)

/*
* Describe an inode's exact location on disk and in memory
Expand Down Expand Up @@ -2098,21 +2109,16 @@ int ext4_fname_disk_to_usr(struct ext4_fname_crypto_ctx *ctx,
int ext4_fname_usr_to_disk(struct ext4_fname_crypto_ctx *ctx,
const struct qstr *iname,
struct ext4_str *oname);
int ext4_fname_usr_to_hash(struct ext4_fname_crypto_ctx *ctx,
const struct qstr *iname,
struct dx_hash_info *hinfo);
int ext4_fname_crypto_namelen_on_disk(struct ext4_fname_crypto_ctx *ctx,
u32 namelen);
int ext4_fname_match(struct ext4_fname_crypto_ctx *ctx, struct ext4_str *cstr,
int len, const char * const name,
struct ext4_dir_entry_2 *de);


#ifdef CONFIG_EXT4_FS_ENCRYPTION
void ext4_put_fname_crypto_ctx(struct ext4_fname_crypto_ctx **ctx);
struct ext4_fname_crypto_ctx *ext4_get_fname_crypto_ctx(struct inode *inode,
u32 max_len);
void ext4_fname_crypto_free_buffer(struct ext4_str *crypto_str);
int ext4_fname_setup_filename(struct inode *dir, const struct qstr *iname,
int lookup, struct ext4_filename *fname);
void ext4_fname_free_filename(struct ext4_filename *fname);
#else
static inline
void ext4_put_fname_crypto_ctx(struct ext4_fname_crypto_ctx **ctx) { }
Expand All @@ -2123,6 +2129,16 @@ struct ext4_fname_crypto_ctx *ext4_get_fname_crypto_ctx(struct inode *inode,
return NULL;
}
static inline void ext4_fname_crypto_free_buffer(struct ext4_str *p) { }
static inline int ext4_fname_setup_filename(struct inode *dir,
const struct qstr *iname,
int lookup, struct ext4_filename *fname)
{
fname->usr_fname = iname;
fname->disk_name.name = (unsigned char *) iname->name;
fname->disk_name.len = iname->len;
return 0;
}
static inline void ext4_fname_free_filename(struct ext4_filename *fname) { }
#endif


Expand Down Expand Up @@ -2156,14 +2172,13 @@ extern void ext4_htree_free_dir_info(struct dir_private_info *p);
extern int ext4_find_dest_de(struct inode *dir, struct inode *inode,
struct buffer_head *bh,
void *buf, int buf_size,
const char *name, int namelen,
struct ext4_filename *fname,
struct ext4_dir_entry_2 **dest_de);
int ext4_insert_dentry(struct inode *dir,
struct inode *inode,
struct ext4_dir_entry_2 *de,
int buf_size,
const struct qstr *iname,
const char *name, int namelen);
struct inode *inode,
struct ext4_dir_entry_2 *de,
int buf_size,
struct ext4_filename *fname);
static inline void ext4_update_dx_flag(struct inode *inode)
{
if (!EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
Expand Down Expand Up @@ -2317,13 +2332,14 @@ extern int ext4_orphan_add(handle_t *, struct inode *);
extern int ext4_orphan_del(handle_t *, struct inode *);
extern int ext4_htree_fill_tree(struct file *dir_file, __u32 start_hash,
__u32 start_minor_hash, __u32 *next_hash);
extern int search_dir(struct buffer_head *bh,
char *search_buf,
int buf_size,
struct inode *dir,
const struct qstr *d_name,
unsigned int offset,
struct ext4_dir_entry_2 **res_dir);
extern int ext4_search_dir(struct buffer_head *bh,
char *search_buf,
int buf_size,
struct inode *dir,
struct ext4_filename *fname,
const struct qstr *d_name,
unsigned int offset,
struct ext4_dir_entry_2 **res_dir);
extern int ext4_generic_delete_entry(handle_t *handle,
struct inode *dir,
struct ext4_dir_entry_2 *de_del,
Expand Down Expand Up @@ -2768,7 +2784,9 @@ extern int ext4_da_write_inline_data_begin(struct address_space *mapping,
extern int ext4_da_write_inline_data_end(struct inode *inode, loff_t pos,
unsigned len, unsigned copied,
struct page *page);
extern int ext4_try_add_inline_entry(handle_t *handle, struct dentry *dentry,
extern int ext4_try_add_inline_entry(handle_t *handle,
struct ext4_filename *fname,
struct dentry *dentry,
struct inode *inode);
extern int ext4_try_create_inline_dir(handle_t *handle,
struct inode *parent,
Expand All @@ -2782,6 +2800,7 @@ extern int htree_inlinedir_to_tree(struct file *dir_file,
__u32 start_hash, __u32 start_minor_hash,
int *has_inline_data);
extern struct buffer_head *ext4_find_inline_entry(struct inode *dir,
struct ext4_filename *fname,
const struct qstr *d_name,
struct ext4_dir_entry_2 **res_dir,
int *has_inline_data);
Expand Down
31 changes: 15 additions & 16 deletions fs/ext4/inline.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -995,29 +995,26 @@ void ext4_show_inline_dir(struct inode *dir, struct buffer_head *bh,
* and -EEXIST if directory entry already exists.
*/
static int ext4_add_dirent_to_inline(handle_t *handle,
struct ext4_filename *fname,
struct dentry *dentry,
struct inode *inode,
struct ext4_iloc *iloc,
void *inline_start, int inline_size)
{
struct inode *dir = d_inode(dentry->d_parent);
const char *name = dentry->d_name.name;
int namelen = dentry->d_name.len;
int err;
struct ext4_dir_entry_2 *de;

err = ext4_find_dest_de(dir, inode, iloc->bh,
inline_start, inline_size,
name, namelen, &de);
err = ext4_find_dest_de(dir, inode, iloc->bh, inline_start,
inline_size, fname, &de);
if (err)
return err;

BUFFER_TRACE(iloc->bh, "get_write_access");
err = ext4_journal_get_write_access(handle, iloc->bh);
if (err)
return err;
ext4_insert_dentry(dir, inode, de, inline_size, &dentry->d_name,
name, namelen);
ext4_insert_dentry(dir, inode, de, inline_size, fname);

ext4_show_inline_dir(dir, iloc->bh, inline_start, inline_size);

Expand Down Expand Up @@ -1248,8 +1245,8 @@ static int ext4_convert_inline_data_nolock(handle_t *handle,
* If succeeds, return 0. If not, extended the inline dir and copied data to
* the new created block.
*/
int ext4_try_add_inline_entry(handle_t *handle, struct dentry *dentry,
struct inode *inode)
int ext4_try_add_inline_entry(handle_t *handle, struct ext4_filename *fname,
struct dentry *dentry, struct inode *inode)
{
int ret, inline_size;
void *inline_start;
Expand All @@ -1268,7 +1265,7 @@ int ext4_try_add_inline_entry(handle_t *handle, struct dentry *dentry,
EXT4_INLINE_DOTDOT_SIZE;
inline_size = EXT4_MIN_INLINE_DATA_SIZE - EXT4_INLINE_DOTDOT_SIZE;

ret = ext4_add_dirent_to_inline(handle, dentry, inode, &iloc,
ret = ext4_add_dirent_to_inline(handle, fname, dentry, inode, &iloc,
inline_start, inline_size);
if (ret != -ENOSPC)
goto out;
Expand All @@ -1289,8 +1286,9 @@ int ext4_try_add_inline_entry(handle_t *handle, struct dentry *dentry,
if (inline_size) {
inline_start = ext4_get_inline_xattr_pos(dir, &iloc);

ret = ext4_add_dirent_to_inline(handle, dentry, inode, &iloc,
inline_start, inline_size);
ret = ext4_add_dirent_to_inline(handle, fname, dentry,
inode, &iloc, inline_start,
inline_size);

if (ret != -ENOSPC)
goto out;
Expand Down Expand Up @@ -1611,6 +1609,7 @@ int ext4_try_create_inline_dir(handle_t *handle, struct inode *parent,
}

struct buffer_head *ext4_find_inline_entry(struct inode *dir,
struct ext4_filename *fname,
const struct qstr *d_name,
struct ext4_dir_entry_2 **res_dir,
int *has_inline_data)
Expand All @@ -1632,8 +1631,8 @@ struct buffer_head *ext4_find_inline_entry(struct inode *dir,
inline_start = (void *)ext4_raw_inode(&iloc)->i_block +
EXT4_INLINE_DOTDOT_SIZE;
inline_size = EXT4_MIN_INLINE_DATA_SIZE - EXT4_INLINE_DOTDOT_SIZE;
ret = search_dir(iloc.bh, inline_start, inline_size,
dir, d_name, 0, res_dir);
ret = ext4_search_dir(iloc.bh, inline_start, inline_size,
dir, fname, d_name, 0, res_dir);
if (ret == 1)
goto out_find;
if (ret < 0)
Expand All @@ -1645,8 +1644,8 @@ struct buffer_head *ext4_find_inline_entry(struct inode *dir,
inline_start = ext4_get_inline_xattr_pos(dir, &iloc);
inline_size = ext4_get_inline_size(dir) - EXT4_MIN_INLINE_DATA_SIZE;

ret = search_dir(iloc.bh, inline_start, inline_size,
dir, d_name, 0, res_dir);
ret = ext4_search_dir(iloc.bh, inline_start, inline_size,
dir, fname, d_name, 0, res_dir);
if (ret == 1)
goto out_find;

Expand Down
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