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Tyler Hicks
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eCryptfs: Cleanup and optimize ecryptfs_lookup_interpose()
ecryptfs_lookup_interpose() has turned into spaghetti code over the years. This is an effort to clean it up. - Shorten overly descriptive variable names such as ecryptfs_dentry - Simplify gotos and error paths - Create helper function for reading plaintext i_size from metadata It also includes an optimization when reading i_size from the metadata. A complete page-sized kmem_cache_alloc() was being done to read in 16 bytes of metadata. The buffer for that is now statically declared. Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>
1 parent 7a86617 commit 778aeb4

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3 files changed

+88
-105
lines changed

3 files changed

+88
-105
lines changed

‎fs/ecryptfs/crypto.c

Lines changed: 21 additions & 24 deletions
Original file line numberDiff line numberDiff line change
@@ -1201,24 +1201,19 @@ int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
12011201
return rc;
12021202
}
12031203

1204-
int ecryptfs_read_and_validate_header_region(char *data,
1205-
struct inode *ecryptfs_inode)
1204+
int ecryptfs_read_and_validate_header_region(struct inode *inode)
12061205
{
1207-
struct ecryptfs_crypt_stat *crypt_stat =
1208-
&(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
1206+
u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1207+
u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
12091208
int rc;
12101209

1211-
if (crypt_stat->extent_size == 0)
1212-
crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
1213-
rc = ecryptfs_read_lower(data, 0, crypt_stat->extent_size,
1214-
ecryptfs_inode);
1215-
if (rc < 0) {
1216-
printk(KERN_ERR "%s: Error reading header region; rc = [%d]\n",
1217-
__func__, rc);
1218-
goto out;
1219-
}
1220-
rc = ecryptfs_validate_marker(data + ECRYPTFS_FILE_SIZE_BYTES);
1221-
out:
1210+
rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
1211+
inode);
1212+
if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1213+
return rc >= 0 ? -EINVAL : rc;
1214+
rc = ecryptfs_validate_marker(marker);
1215+
if (!rc)
1216+
ecryptfs_i_size_init(file_size, inode);
12221217
return rc;
12231218
}
12241219

@@ -1562,19 +1557,21 @@ int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
15621557
return rc;
15631558
}
15641559

1565-
int ecryptfs_read_and_validate_xattr_region(char *page_virt,
1560+
int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
15661561
struct inode *inode)
15671562
{
1563+
u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1564+
u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
15681565
int rc;
15691566

1570-
rc = ecryptfs_read_xattr_region(page_virt, inode);
1571-
if (rc)
1572-
goto out;
1573-
rc = ecryptfs_validate_marker(page_virt + ECRYPTFS_FILE_SIZE_BYTES);
1574-
if (rc)
1575-
printk(KERN_WARNING "Valid data found in [%s] xattr, but "
1576-
"the marker is invalid\n", ECRYPTFS_XATTR_NAME);
1577-
out:
1567+
rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
1568+
ECRYPTFS_XATTR_NAME, file_size,
1569+
ECRYPTFS_SIZE_AND_MARKER_BYTES);
1570+
if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1571+
return rc >= 0 ? -EINVAL : rc;
1572+
rc = ecryptfs_validate_marker(marker);
1573+
if (!rc)
1574+
ecryptfs_i_size_init(file_size, inode);
15781575
return rc;
15791576
}
15801577

‎fs/ecryptfs/ecryptfs_kernel.h

Lines changed: 4 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -200,6 +200,8 @@ ecryptfs_get_key_payload_data(struct key *key)
200200
#define MAGIC_ECRYPTFS_MARKER 0x3c81b7f5
201201
#define MAGIC_ECRYPTFS_MARKER_SIZE_BYTES 8 /* 4*2 */
202202
#define ECRYPTFS_FILE_SIZE_BYTES (sizeof(u64))
203+
#define ECRYPTFS_SIZE_AND_MARKER_BYTES (ECRYPTFS_FILE_SIZE_BYTES \
204+
+ MAGIC_ECRYPTFS_MARKER_SIZE_BYTES)
203205
#define ECRYPTFS_DEFAULT_CIPHER "aes"
204206
#define ECRYPTFS_DEFAULT_KEY_BYTES 16
205207
#define ECRYPTFS_DEFAULT_HASH "md5"
@@ -659,9 +661,8 @@ int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry);
659661
void ecryptfs_write_crypt_stat_flags(char *page_virt,
660662
struct ecryptfs_crypt_stat *crypt_stat,
661663
size_t *written);
662-
int ecryptfs_read_and_validate_header_region(char *data,
663-
struct inode *ecryptfs_inode);
664-
int ecryptfs_read_and_validate_xattr_region(char *page_virt,
664+
int ecryptfs_read_and_validate_header_region(struct inode *inode);
665+
int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
665666
struct inode *inode);
666667
u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes);
667668
int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code);

‎fs/ecryptfs/inode.c

Lines changed: 63 additions & 78 deletions
Original file line numberDiff line numberDiff line change
@@ -307,105 +307,90 @@ ecryptfs_create(struct inode *directory_inode, struct dentry *ecryptfs_dentry,
307307
return rc;
308308
}
309309

310+
static int ecryptfs_i_size_read(struct dentry *dentry, struct inode *inode)
311+
{
312+
struct ecryptfs_crypt_stat *crypt_stat;
313+
int rc;
314+
315+
rc = ecryptfs_get_lower_file(dentry, inode);
316+
if (rc) {
317+
printk(KERN_ERR "%s: Error attempting to initialize "
318+
"the lower file for the dentry with name "
319+
"[%s]; rc = [%d]\n", __func__,
320+
dentry->d_name.name, rc);
321+
return rc;
322+
}
323+
324+
crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
325+
/* TODO: lock for crypt_stat comparison */
326+
if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED))
327+
ecryptfs_set_default_sizes(crypt_stat);
328+
329+
rc = ecryptfs_read_and_validate_header_region(inode);
330+
ecryptfs_put_lower_file(inode);
331+
if (rc) {
332+
rc = ecryptfs_read_and_validate_xattr_region(dentry, inode);
333+
if (!rc)
334+
crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
335+
}
336+
337+
/* Must return 0 to allow non-eCryptfs files to be looked up, too */
338+
return 0;
339+
}
340+
310341
/**
311342
* ecryptfs_lookup_interpose - Dentry interposition for a lookup
312343
*/
313-
static int ecryptfs_lookup_interpose(struct dentry *ecryptfs_dentry,
344+
static int ecryptfs_lookup_interpose(struct dentry *dentry,
314345
struct dentry *lower_dentry,
315-
struct inode *ecryptfs_dir_inode)
346+
struct inode *dir_inode)
316347
{
317-
struct dentry *lower_dir_dentry;
348+
struct inode *inode, *lower_inode = lower_dentry->d_inode;
349+
struct ecryptfs_dentry_info *dentry_info;
318350
struct vfsmount *lower_mnt;
319-
struct inode *inode, *lower_inode;
320-
struct ecryptfs_crypt_stat *crypt_stat;
321-
char *page_virt = NULL;
322-
int put_lower = 0, rc = 0;
323-
324-
lower_dir_dentry = lower_dentry->d_parent;
325-
lower_mnt = mntget(ecryptfs_dentry_to_lower_mnt(
326-
ecryptfs_dentry->d_parent));
327-
lower_inode = lower_dentry->d_inode;
328-
fsstack_copy_attr_atime(ecryptfs_dir_inode, lower_dir_dentry->d_inode);
351+
int rc = 0;
352+
353+
lower_mnt = mntget(ecryptfs_dentry_to_lower_mnt(dentry->d_parent));
354+
fsstack_copy_attr_atime(dir_inode, lower_dentry->d_parent->d_inode);
329355
BUG_ON(!lower_dentry->d_count);
330-
ecryptfs_set_dentry_private(ecryptfs_dentry,
331-
kmem_cache_alloc(ecryptfs_dentry_info_cache,
332-
GFP_KERNEL));
333-
if (!ecryptfs_dentry_to_private(ecryptfs_dentry)) {
334-
rc = -ENOMEM;
356+
357+
dentry_info = kmem_cache_alloc(ecryptfs_dentry_info_cache, GFP_KERNEL);
358+
ecryptfs_set_dentry_private(dentry, dentry_info);
359+
if (!dentry_info) {
335360
printk(KERN_ERR "%s: Out of memory whilst attempting "
336361
"to allocate ecryptfs_dentry_info struct\n",
337362
__func__);
338-
goto out_put;
363+
dput(lower_dentry);
364+
mntput(lower_mnt);
365+
d_drop(dentry);
366+
return -ENOMEM;
339367
}
340-
ecryptfs_set_dentry_lower(ecryptfs_dentry, lower_dentry);
341-
ecryptfs_set_dentry_lower_mnt(ecryptfs_dentry, lower_mnt);
368+
ecryptfs_set_dentry_lower(dentry, lower_dentry);
369+
ecryptfs_set_dentry_lower_mnt(dentry, lower_mnt);
370+
342371
if (!lower_dentry->d_inode) {
343372
/* We want to add because we couldn't find in lower */
344-
d_add(ecryptfs_dentry, NULL);
345-
goto out;
373+
d_add(dentry, NULL);
374+
return 0;
346375
}
347-
inode = __ecryptfs_get_inode(lower_inode, ecryptfs_dir_inode->i_sb);
376+
inode = __ecryptfs_get_inode(lower_inode, dir_inode->i_sb);
348377
if (IS_ERR(inode)) {
349-
rc = PTR_ERR(inode);
350-
printk(KERN_ERR "%s: Error interposing; rc = [%d]\n",
351-
__func__, rc);
352-
goto out;
353-
}
354-
if (!S_ISREG(inode->i_mode)) {
355-
if (inode->i_state & I_NEW)
356-
unlock_new_inode(inode);
357-
d_add(ecryptfs_dentry, inode);
358-
goto out;
359-
}
360-
/* Released in this function */
361-
page_virt = kmem_cache_zalloc(ecryptfs_header_cache_2, GFP_USER);
362-
if (!page_virt) {
363-
printk(KERN_ERR "%s: Cannot kmem_cache_zalloc() a page\n",
364-
__func__);
365-
rc = -ENOMEM;
366-
make_bad_inode(inode);
367-
goto out;
368-
}
369-
rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
370-
if (rc) {
371-
printk(KERN_ERR "%s: Error attempting to initialize "
372-
"the lower file for the dentry with name "
373-
"[%s]; rc = [%d]\n", __func__,
374-
ecryptfs_dentry->d_name.name, rc);
375-
make_bad_inode(inode);
376-
goto out_free_kmem;
378+
printk(KERN_ERR "%s: Error interposing; rc = [%ld]\n",
379+
__func__, PTR_ERR(inode));
380+
return PTR_ERR(inode);
377381
}
378-
put_lower = 1;
379-
crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
380-
/* TODO: lock for crypt_stat comparison */
381-
if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED))
382-
ecryptfs_set_default_sizes(crypt_stat);
383-
rc = ecryptfs_read_and_validate_header_region(page_virt, inode);
384-
if (rc) {
385-
memset(page_virt, 0, PAGE_CACHE_SIZE);
386-
rc = ecryptfs_read_and_validate_xattr_region(page_virt,
387-
inode);
382+
if (S_ISREG(inode->i_mode)) {
383+
rc = ecryptfs_i_size_read(dentry, inode);
388384
if (rc) {
389-
rc = 0;
390-
goto unlock_inode;
385+
make_bad_inode(inode);
386+
return rc;
391387
}
392-
crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
393388
}
394-
ecryptfs_i_size_init(page_virt, inode);
395-
unlock_inode:
389+
396390
if (inode->i_state & I_NEW)
397391
unlock_new_inode(inode);
398-
d_add(ecryptfs_dentry, inode);
399-
out_free_kmem:
400-
kmem_cache_free(ecryptfs_header_cache_2, page_virt);
401-
goto out;
402-
out_put:
403-
dput(lower_dentry);
404-
mntput(lower_mnt);
405-
d_drop(ecryptfs_dentry);
406-
out:
407-
if (put_lower)
408-
ecryptfs_put_lower_file(inode);
392+
d_add(dentry, inode);
393+
409394
return rc;
410395
}
411396

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