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Tyler Hicks
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eCryptfs: Fix new inode race condition
Only unlock and d_add() new inodes after the plaintext inode size has been read from the lower filesystem. This fixes a race condition that was sometimes seen during a multi-job kernel build in an eCryptfs mount. https://bugzilla.kernel.org/show_bug.cgi?id=36002 Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com> Reported-by: David <david@unsolicited.net> Tested-by: David <david@unsolicited.net>
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5 files changed

+30
-28
lines changed

5 files changed

+30
-28
lines changed

‎fs/ecryptfs/crypto.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1568,11 +1568,11 @@ int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
15681568
}
15691569

15701570
int ecryptfs_read_and_validate_xattr_region(char *page_virt,
1571-
struct dentry *ecryptfs_dentry)
1571+
struct inode *inode)
15721572
{
15731573
int rc;
15741574

1575-
rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_dentry->d_inode);
1575+
rc = ecryptfs_read_xattr_region(page_virt, inode);
15761576
if (rc)
15771577
goto out;
15781578
if (!contains_ecryptfs_marker(page_virt + ECRYPTFS_FILE_SIZE_BYTES)) {

‎fs/ecryptfs/ecryptfs_kernel.h

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -662,7 +662,7 @@ void ecryptfs_write_crypt_stat_flags(char *page_virt,
662662
int ecryptfs_read_and_validate_header_region(char *data,
663663
struct inode *ecryptfs_inode);
664664
int ecryptfs_read_and_validate_xattr_region(char *page_virt,
665-
struct dentry *ecryptfs_dentry);
665+
struct inode *inode);
666666
u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes);
667667
int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code);
668668
void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat);
@@ -753,7 +753,7 @@ int ecryptfs_privileged_open(struct file **lower_file,
753753
struct dentry *lower_dentry,
754754
struct vfsmount *lower_mnt,
755755
const struct cred *cred);
756-
int ecryptfs_get_lower_file(struct dentry *ecryptfs_dentry);
756+
int ecryptfs_get_lower_file(struct dentry *dentry, struct inode *inode);
757757
void ecryptfs_put_lower_file(struct inode *inode);
758758
int
759759
ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,

‎fs/ecryptfs/file.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -191,7 +191,7 @@ static int ecryptfs_open(struct inode *inode, struct file *file)
191191
| ECRYPTFS_ENCRYPTED);
192192
}
193193
mutex_unlock(&crypt_stat->cs_mutex);
194-
rc = ecryptfs_get_lower_file(ecryptfs_dentry);
194+
rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
195195
if (rc) {
196196
printk(KERN_ERR "%s: Error attempting to initialize "
197197
"the lower file for the dentry with name "

‎fs/ecryptfs/inode.c

Lines changed: 22 additions & 20 deletions
Original file line numberDiff line numberDiff line change
@@ -259,7 +259,8 @@ static int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry)
259259
"context; rc = [%d]\n", rc);
260260
goto out;
261261
}
262-
rc = ecryptfs_get_lower_file(ecryptfs_dentry);
262+
rc = ecryptfs_get_lower_file(ecryptfs_dentry,
263+
ecryptfs_dentry->d_inode);
263264
if (rc) {
264265
printk(KERN_ERR "%s: Error attempting to initialize "
265266
"the lower file for the dentry with name "
@@ -350,50 +351,51 @@ static int ecryptfs_lookup_interpose(struct dentry *ecryptfs_dentry,
350351
__func__, rc);
351352
goto out;
352353
}
353-
if (inode->i_state & I_NEW)
354-
unlock_new_inode(inode);
355-
d_add(ecryptfs_dentry, inode);
356-
if (S_ISDIR(lower_inode->i_mode))
357-
goto out;
358-
if (S_ISLNK(lower_inode->i_mode))
359-
goto out;
360-
if (special_file(lower_inode->i_mode))
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);
361358
goto out;
359+
}
362360
/* Released in this function */
363361
page_virt = kmem_cache_zalloc(ecryptfs_header_cache_2, GFP_USER);
364362
if (!page_virt) {
365363
printk(KERN_ERR "%s: Cannot kmem_cache_zalloc() a page\n",
366364
__func__);
367365
rc = -ENOMEM;
366+
make_bad_inode(inode);
368367
goto out;
369368
}
370-
rc = ecryptfs_get_lower_file(ecryptfs_dentry);
369+
rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
371370
if (rc) {
372371
printk(KERN_ERR "%s: Error attempting to initialize "
373372
"the lower file for the dentry with name "
374373
"[%s]; rc = [%d]\n", __func__,
375374
ecryptfs_dentry->d_name.name, rc);
375+
make_bad_inode(inode);
376376
goto out_free_kmem;
377377
}
378378
put_lower = 1;
379-
crypt_stat = &ecryptfs_inode_to_private(
380-
ecryptfs_dentry->d_inode)->crypt_stat;
379+
crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
381380
/* TODO: lock for crypt_stat comparison */
382381
if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED))
383382
ecryptfs_set_default_sizes(crypt_stat);
384-
rc = ecryptfs_read_and_validate_header_region(page_virt,
385-
ecryptfs_dentry->d_inode);
383+
rc = ecryptfs_read_and_validate_header_region(page_virt, inode);
386384
if (rc) {
387385
memset(page_virt, 0, PAGE_CACHE_SIZE);
388386
rc = ecryptfs_read_and_validate_xattr_region(page_virt,
389-
ecryptfs_dentry);
387+
inode);
390388
if (rc) {
391389
rc = 0;
392-
goto out_free_kmem;
390+
goto unlock_inode;
393391
}
394392
crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
395393
}
396-
ecryptfs_i_size_init(page_virt, ecryptfs_dentry->d_inode);
394+
ecryptfs_i_size_init(page_virt, inode);
395+
unlock_inode:
396+
if (inode->i_state & I_NEW)
397+
unlock_new_inode(inode);
398+
d_add(ecryptfs_dentry, inode);
397399
out_free_kmem:
398400
kmem_cache_free(ecryptfs_header_cache_2, page_virt);
399401
goto out;
@@ -403,7 +405,7 @@ static int ecryptfs_lookup_interpose(struct dentry *ecryptfs_dentry,
403405
d_drop(ecryptfs_dentry);
404406
out:
405407
if (put_lower)
406-
ecryptfs_put_lower_file(ecryptfs_dentry->d_inode);
408+
ecryptfs_put_lower_file(inode);
407409
return rc;
408410
}
409411

@@ -843,7 +845,7 @@ static int truncate_upper(struct dentry *dentry, struct iattr *ia,
843845
lower_ia->ia_valid &= ~ATTR_SIZE;
844846
return 0;
845847
}
846-
rc = ecryptfs_get_lower_file(dentry);
848+
rc = ecryptfs_get_lower_file(dentry, inode);
847849
if (rc)
848850
return rc;
849851
crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
@@ -999,7 +1001,7 @@ static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
9991001

10001002
mount_crypt_stat = &ecryptfs_superblock_to_private(
10011003
dentry->d_sb)->mount_crypt_stat;
1002-
rc = ecryptfs_get_lower_file(dentry);
1004+
rc = ecryptfs_get_lower_file(dentry, inode);
10031005
if (rc) {
10041006
mutex_unlock(&crypt_stat->cs_mutex);
10051007
goto out;

‎fs/ecryptfs/main.c

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -135,12 +135,12 @@ static int ecryptfs_init_lower_file(struct dentry *dentry,
135135
return rc;
136136
}
137137

138-
int ecryptfs_get_lower_file(struct dentry *dentry)
138+
int ecryptfs_get_lower_file(struct dentry *dentry, struct inode *inode)
139139
{
140-
struct ecryptfs_inode_info *inode_info =
141-
ecryptfs_inode_to_private(dentry->d_inode);
140+
struct ecryptfs_inode_info *inode_info;
142141
int count, rc = 0;
143142

143+
inode_info = ecryptfs_inode_to_private(inode);
144144
mutex_lock(&inode_info->lower_file_mutex);
145145
count = atomic_inc_return(&inode_info->lower_file_count);
146146
if (WARN_ON_ONCE(count < 1))

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