[PATCH] ovl: fix wrong flags check in FS_IOC_FS[SG]ETXATTR ioctls

[Amir Goldstein <amir73il@gmail.com>]

The ioctl argument was parsed as the wrong type.

Fixes: b21d9c435f93 ("ovl: support the FS_IOC_FS[SG]ETXATTR ioctls")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---

Miklos,

Please take this braino fix through the "fast track".
I have now an xfstest to verify the fix is correct.
Will post it shortly.

Thanks,
Amir.

 fs/overlayfs/file.c | 91 ++++++++++++++++++++++++++++++++-------------
 1 file changed, 65 insertions(+), 26 deletions(-)

diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index 340a6ad45914..75d8d00fa087 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -409,37 +409,16 @@ static long ovl_real_ioctl(struct file *file, unsigned int cmd,
 	return ret;
 }
 
-static unsigned int ovl_get_inode_flags(struct inode *inode)
-{
-	unsigned int flags = READ_ONCE(inode->i_flags);
-	unsigned int ovl_iflags = 0;
-
-	if (flags & S_SYNC)
-		ovl_iflags |= FS_SYNC_FL;
-	if (flags & S_APPEND)
-		ovl_iflags |= FS_APPEND_FL;
-	if (flags & S_IMMUTABLE)
-		ovl_iflags |= FS_IMMUTABLE_FL;
-	if (flags & S_NOATIME)
-		ovl_iflags |= FS_NOATIME_FL;
-
-	return ovl_iflags;
-}
-
 static long ovl_ioctl_set_flags(struct file *file, unsigned int cmd,
-				unsigned long arg)
+				unsigned long arg, unsigned int iflags)
 {
 	long ret;
 	struct inode *inode = file_inode(file);
-	unsigned int flags;
-	unsigned int old_flags;
+	unsigned int old_iflags;
 
 	if (!inode_owner_or_capable(inode))
 		return -EACCES;
 
-	if (get_user(flags, (int __user *) arg))
-		return -EFAULT;
-
 	ret = mnt_want_write_file(file);
 	if (ret)
 		return ret;
@@ -448,8 +427,8 @@ static long ovl_ioctl_set_flags(struct file *file, unsigned int cmd,
 
 	/* Check the capability before cred override */
 	ret = -EPERM;
-	old_flags = ovl_get_inode_flags(inode);
-	if (((flags ^ old_flags) & (FS_APPEND_FL | FS_IMMUTABLE_FL)) &&
+	old_iflags = READ_ONCE(inode->i_flags);
+	if (((iflags ^ old_iflags) & (S_APPEND | S_IMMUTABLE)) &&
 	    !capable(CAP_LINUX_IMMUTABLE))
 		goto unlock;
 
@@ -469,6 +448,63 @@ static long ovl_ioctl_set_flags(struct file *file, unsigned int cmd,
 
 }
 
+static unsigned int ovl_fsflags_to_iflags(unsigned int flags)
+{
+	unsigned int iflags = 0;
+
+	if (flags & FS_SYNC_FL)
+		iflags |= S_SYNC;
+	if (flags & FS_APPEND_FL)
+		iflags |= S_APPEND;
+	if (flags & FS_IMMUTABLE_FL)
+		iflags |= S_IMMUTABLE;
+	if (flags & FS_NOATIME_FL)
+		iflags |= S_NOATIME;
+
+	return iflags;
+}
+
+static long ovl_ioctl_set_fsflags(struct file *file, unsigned int cmd,
+				  unsigned long arg)
+{
+	unsigned int flags;
+
+	if (get_user(flags, (int __user *) arg))
+		return -EFAULT;
+
+	return ovl_ioctl_set_flags(file, cmd, arg,
+				   ovl_fsflags_to_iflags(flags));
+}
+
+static unsigned int ovl_fsxflags_to_iflags(unsigned int xflags)
+{
+	unsigned int iflags = 0;
+
+	if (xflags & FS_XFLAG_SYNC)
+		iflags |= S_SYNC;
+	if (xflags & FS_XFLAG_APPEND)
+		iflags |= S_APPEND;
+	if (xflags & FS_XFLAG_IMMUTABLE)
+		iflags |= S_IMMUTABLE;
+	if (xflags & FS_XFLAG_NOATIME)
+		iflags |= S_NOATIME;
+
+	return iflags;
+}
+
+static long ovl_ioctl_set_fsxflags(struct file *file, unsigned int cmd,
+				   unsigned long arg)
+{
+	struct fsxattr fa;
+
+	memset(&fa, 0, sizeof(fa));
+	if (copy_from_user(&fa, (void __user *) arg, sizeof(fa)))
+		return -EFAULT;
+
+	return ovl_ioctl_set_flags(file, cmd, arg,
+				   ovl_fsxflags_to_iflags(fa.fsx_xflags));
+}
+
 static long ovl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
 	long ret;
@@ -480,8 +516,11 @@ static long ovl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		break;
 
 	case FS_IOC_SETFLAGS:
+		ret = ovl_ioctl_set_fsflags(file, cmd, arg);
+		break;
+
 	case FS_IOC_FSSETXATTR:
-		ret = ovl_ioctl_set_flags(file, cmd, arg);
+		ret = ovl_ioctl_set_fsxflags(file, cmd, arg);
 		break;
 
 	default:
-- 
2.17.1