Btrfs: Add workaround for AppArmor changing remove_suid()

In openSUSE 10.3, AppArmor modifies remove_suid to take a struct path
rather than just a dentry. This patch tests that the kernel is openSUSE
10.3 or newer and adjusts the call accordingly.

Debian/Ubuntu with AppArmor applied will also need a similar patch.
Maintainers of btrfs under those distributions should build on this
patch or, alternatively, alter their package descriptions to add
-DREMOVE_SUID_PATH to the compiler command line.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
- --- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ b/compat.h	2008-02-06 16:46:13.000000000 -0500
@@ -0,0 +1,15 @@
+#ifndef _COMPAT_H_
+#define _COMPAT_H_
+
+
+/*
+ * Even if AppArmor isn't enabled, it still has different prototypes.
+ * Add more distro/version pairs here to declare which has AppArmor applied.
+ */
+#if defined(CONFIG_SUSE_KERNEL)
+# if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,22)
+# define REMOVE_SUID_PATH 1
+# endif
+#endif
+
+#endif /* _COMPAT_H_ */
- --- a/file.c	2008-02-06 11:37:39.000000000 -0500
+++ b/file.c	2008-02-06 16:46:23.000000000 -0500
@@ -37,6 +37,7 @@
 #include "ordered-data.h"
 #include "ioctl.h"
 #include "print-tree.h"
+#include "compat.h"

 static int btrfs_copy_from_user(loff_t pos, int num_pages, int write_bytes,
@@ -790,7 +791,11 @@ static ssize_t btrfs_file_write(struct f
 		goto out_nolock;
 	if (count == 0)
 		goto out_nolock;
+#ifdef REMOVE_SUID_PATH
+	err = remove_suid(&file->f_path);
+#else
 	err = remove_suid(fdentry(file));
+#endif
 	if (err)
 		goto out_nolock;
 	file_update_time(file);

Signed-off-by: Chris Mason <chris.mason@oracle.com>

fs/btrfs/compat.h

@@ -0,0 +1,25 @@
+#ifndef _COMPAT_H_
+#define _COMPAT_H_
+
+
+/*
+ * Even if AppArmor isn't enabled, it still has different prototypes.
+ * Add more distro/version pairs here to declare which has AppArmor applied.
+ */
+#if defined(CONFIG_SUSE_KERNEL)
+# if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,22)
+# define REMOVE_SUID_PATH 1
+# endif
+#endif
+
+/*
+ * catch any other distros that have patched in apparmor.  This isn't
+ * 100% reliable because it won't catch people that hand compile their
+ * own distro kernels without apparmor compiled in.  But, it is better
+ * than nothing.
+ */
+#ifdef CONFIG_SECURITY_APPARMOR
+# define REMOVE_SUID_PATH 1
+#endif
+
+#endif /* _COMPAT_H_ */

fs/btrfs/file.c

@@ -37,6 +37,7 @@
 #include "ordered-data.h"
 #include "ioctl.h"
 #include "print-tree.h"
+#include "compat.h"
 
 
 static int btrfs_copy_from_user(loff_t pos, int num_pages, int write_bytes,
@@ -852,7 +853,11 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
 		goto out_nolock;
 	if (count == 0)
 		goto out_nolock;
+#ifdef REMOVE_SUID_PATH
+	err = remove_suid(&file->f_path);
+#else
 	err = remove_suid(fdentry(file));
+#endif
 	if (err)
 		goto out_nolock;
 	file_update_time(file);