ntfs: fix ntfs_test_inode and ntfs_init_locked_inode function type

Clang's Control Flow Integrity (CFI) is a security mechanism that can help
prevent JOP chains, deployed extensively in downstream kernels used in
Android.

Its deployment is hindered by mismatches in function signatures.  For this
case, we make callbacks match their intended function signature, and cast
parameters within them rather than casting the callback when passed as a
parameter.

When running `mount -t ntfs ...` we observe the following trace:

Call trace:
__cfi_check_fail+0x1c/0x24
name_to_dev_t+0x0/0x404
iget5_locked+0x594/0x5e8
ntfs_fill_super+0xbfc/0x43ec
mount_bdev+0x30c/0x3cc
ntfs_mount+0x18/0x24
mount_fs+0x1b0/0x380
vfs_kern_mount+0x90/0x398
do_mount+0x5d8/0x1a10
SyS_mount+0x108/0x144
el0_svc_naked+0x34/0x38

Signed-off-by: Luca Stefani <luca.stefani.ge1@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: freak07 <michalechner92@googlemail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Anton Altaparmakov <anton@tuxera.com>
Link: http://lkml.kernel.org/r/20200718112513.533800-1-luca.stefani.ge1@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/ntfs/dir.c b/fs/ntfs/dir.c
index a87d4391e6b55d488f659bfb9f69b126b4dce1b3..cd96083a12c8e529f27118da476047df1eb892ed 100644 (file)
--- a/fs/ntfs/dir.c
+++ b/fs/ntfs/dir.c
@@ -1504,7 +1504,7 @@ static int ntfs_dir_fsync(struct file *filp, loff_t start, loff_t end,
        na.type = AT_BITMAP;
        na.name = I30;
        na.name_len = 4;
-       bmp_vi = ilookup5(vi->i_sb, vi->i_ino, (test_t)ntfs_test_inode, &na);
+       bmp_vi = ilookup5(vi->i_sb, vi->i_ino, ntfs_test_inode, &na);
        if (bmp_vi) {
                write_inode_now(bmp_vi, !datasync);
                iput(bmp_vi);

diff --git a/fs/ntfs/inode.c b/fs/ntfs/inode.c
index d4359a1df3d5ecd9d152518ddb66a9fc5e9074d0..9bb9f0952b1865a38a5224808a52ec0a6e13751e 100644 (file)
--- a/fs/ntfs/inode.c
+++ b/fs/ntfs/inode.c
@@ -30,10 +30,10 @@
 /**
  * ntfs_test_inode - compare two (possibly fake) inodes for equality
  * @vi:                vfs inode which to test
- * @na:                ntfs attribute which is being tested with
+ * @data:      data which is being tested with
  *
  * Compare the ntfs attribute embedded in the ntfs specific part of the vfs
- * inode @vi for equality with the ntfs attribute @na.
+ * inode @vi for equality with the ntfs attribute @data.
  *
  * If searching for the normal file/directory inode, set @na->type to AT_UNUSED.
  * @na->name and @na->name_len are then ignored.
@@ -43,8 +43,9 @@
  * NOTE: This function runs with the inode_hash_lock spin lock held so it is not
  * allowed to sleep.
  */
-int ntfs_test_inode(struct inode *vi, ntfs_attr *na)
+int ntfs_test_inode(struct inode *vi, void *data)
 {
+       ntfs_attr *na = (ntfs_attr *)data;
        ntfs_inode *ni;
 
        if (vi->i_ino != na->mft_no)
@@ -72,9 +73,9 @@ int ntfs_test_inode(struct inode *vi, ntfs_attr *na)
 /**
  * ntfs_init_locked_inode - initialize an inode
  * @vi:                vfs inode to initialize
- * @na:                ntfs attribute which to initialize @vi to
+ * @data:      data which to initialize @vi to
  *
- * Initialize the vfs inode @vi with the values from the ntfs attribute @na in
+ * Initialize the vfs inode @vi with the values from the ntfs attribute @data in
  * order to enable ntfs_test_inode() to do its work.
  *
  * If initializing the normal file/directory inode, set @na->type to AT_UNUSED.
@@ -87,8 +88,9 @@ int ntfs_test_inode(struct inode *vi, ntfs_attr *na)
  * NOTE: This function runs with the inode->i_lock spin lock held so it is not
  * allowed to sleep. (Hence the GFP_ATOMIC allocation.)
  */
-static int ntfs_init_locked_inode(struct inode *vi, ntfs_attr *na)
+static int ntfs_init_locked_inode(struct inode *vi, void *data)
 {
+       ntfs_attr *na = (ntfs_attr *)data;
        ntfs_inode *ni = NTFS_I(vi);
 
        vi->i_ino = na->mft_no;
@@ -131,7 +133,6 @@ static int ntfs_init_locked_inode(struct inode *vi, ntfs_attr *na)
        return 0;
 }
 
-typedef int (*set_t)(struct inode *, void *);
 static int ntfs_read_locked_inode(struct inode *vi);
 static int ntfs_read_locked_attr_inode(struct inode *base_vi, struct inode *vi);
 static int ntfs_read_locked_index_inode(struct inode *base_vi,
@@ -164,8 +165,8 @@ struct inode *ntfs_iget(struct super_block *sb, unsigned long mft_no)
        na.name = NULL;
        na.name_len = 0;
 
-       vi = iget5_locked(sb, mft_no, (test_t)ntfs_test_inode,
-                       (set_t)ntfs_init_locked_inode, &na);
+       vi = iget5_locked(sb, mft_no, ntfs_test_inode,
+                       ntfs_init_locked_inode, &na);
        if (unlikely(!vi))
                return ERR_PTR(-ENOMEM);
 
@@ -225,8 +226,8 @@ struct inode *ntfs_attr_iget(struct inode *base_vi, ATTR_TYPE type,
        na.name = name;
        na.name_len = name_len;
 
-       vi = iget5_locked(base_vi->i_sb, na.mft_no, (test_t)ntfs_test_inode,
-                       (set_t)ntfs_init_locked_inode, &na);
+       vi = iget5_locked(base_vi->i_sb, na.mft_no, ntfs_test_inode,
+                       ntfs_init_locked_inode, &na);
        if (unlikely(!vi))
                return ERR_PTR(-ENOMEM);
 
@@ -280,8 +281,8 @@ struct inode *ntfs_index_iget(struct inode *base_vi, ntfschar *name,
        na.name = name;
        na.name_len = name_len;
 
-       vi = iget5_locked(base_vi->i_sb, na.mft_no, (test_t)ntfs_test_inode,
-                       (set_t)ntfs_init_locked_inode, &na);
+       vi = iget5_locked(base_vi->i_sb, na.mft_no, ntfs_test_inode,
+                       ntfs_init_locked_inode, &na);
        if (unlikely(!vi))
                return ERR_PTR(-ENOMEM);
 

diff --git a/fs/ntfs/inode.h b/fs/ntfs/inode.h
index 98e670fbdd31d2d25cb9c7e7ae528557c1c05d22..363e4e8206738dd5267eb0b4e079336b208d08ff 100644 (file)
--- a/fs/ntfs/inode.h
+++ b/fs/ntfs/inode.h
@@ -253,9 +253,7 @@ typedef struct {
        ATTR_TYPE type;
 } ntfs_attr;
 
-typedef int (*test_t)(struct inode *, void *);
-
-extern int ntfs_test_inode(struct inode *vi, ntfs_attr *na);
+extern int ntfs_test_inode(struct inode *vi, void *data);
 
 extern struct inode *ntfs_iget(struct super_block *sb, unsigned long mft_no);
 extern struct inode *ntfs_attr_iget(struct inode *base_vi, ATTR_TYPE type,

diff --git a/fs/ntfs/mft.c b/fs/ntfs/mft.c
index fbb9f1bc623dc555c0f9ced52e11fd158209c09c..0d62cd5bb7f8456b545cb9cc28d7f35fc687fdef 100644 (file)
--- a/fs/ntfs/mft.c
+++ b/fs/ntfs/mft.c
@@ -958,7 +958,7 @@ bool ntfs_may_write_mft_record(ntfs_volume *vol, const unsigned long mft_no,
                 * dirty code path of the inode dirty code path when writing
                 * $MFT occurs.
                 */
-               vi = ilookup5_nowait(sb, mft_no, (test_t)ntfs_test_inode, &na);
+               vi = ilookup5_nowait(sb, mft_no, ntfs_test_inode, &na);
        }
        if (vi) {
                ntfs_debug("Base inode 0x%lx is in icache.", mft_no);
@@ -1019,7 +1019,7 @@ bool ntfs_may_write_mft_record(ntfs_volume *vol, const unsigned long mft_no,
                vi = igrab(mft_vi);
                BUG_ON(vi != mft_vi);
        } else
-               vi = ilookup5_nowait(sb, na.mft_no, (test_t)ntfs_test_inode,
+               vi = ilookup5_nowait(sb, na.mft_no, ntfs_test_inode,
                                &na);
        if (!vi) {
                /*