path: root/sys-fs/zfs-kmod/files/zfs-kmod-0.6.0_rc14-improved-hardened-support.patch

From ead579050140bfa010d06f6e0fea3f680c781b38 Mon Sep 17 00:00:00 2001
From: Richard Yao <ryao@cs.stonybrook.edu>
Date: Thu, 14 Feb 2013 18:54:04 -0500
Subject: [PATCH] Eliminate runtime function pointer modifications in
 autotools checks
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

PaX/GrSecurity patched kernels implement a dialect of C that relies on a
GCC plugin for enforcement. A basic idea in this dialect is that
function pointers in structures should not change during runtime.
This causes code that modifies function pointers at runtime to fail to
compile in many instances. The autotools checks rely on whether or
not small test cases compile against a given kernel. Some
autotools checks assume some default case if other cases fail. When one
of these autotools checks tests a PaX/GrSecurity patched kernel by
modifying a function pointer at runtime, the default case will be used.

Early detection of such situations is possible by relying on compiler
warnings, which are compiler errors when --enable-debug is used.
Unfortunately, very few people build ZFS with --enable-debug. The more
common situation is that these issues manifest themselves as runtime
failures in the form of NULL pointer exceptions.

Previous patches that addressed such issues with PaX/GrSecurity
compatibility largely relied on rewriting autotools checks to avoid
runtime function pointer modification or the addition of PaX/GrSecurity
specific checks. This patch takes the previous work to its logical
conclusion by eliminating the use of runtime function pointer
modification. This permits the removal of PaX-specific autotools checks
in favor of ones that work across all supported kernels.

This should resolve issues that were reported to occur with
PaX/GrSecurity-patched Linux 3.7.5 kernels on Gentoo Linux.

https://bugs.gentoo.org/show_bug.cgi?id=457176

We should be able to prevent future regressions in PaX/GrSecurity
compatibility by ensuring that all changes to ZFSOnLinux avoid runtime
function pointer modification. At the same time, this does not solve the
issue of silent failures triggering default cases in the autotools
check, which is what permitted these regressions to become runtime
failures in the first place. This will need to be addressed in a future
patch.

Reported-by: Marcin Mirosław <bug@mejor.pl>
Signed-off-by: Richard Yao <ryao@cs.stonybrook.edu>
---
 config/kernel-bdev-block-device-operations.m4 |   21 +++----
 config/kernel-bio-end-io-t-args.m4            |    6 +-
 config/kernel-create-nameidata.m4             |   12 ++--
 config/kernel-dentry-operations.m4            |    6 +-
 config/kernel-dirty-inode.m4                  |    8 +--
 config/kernel-fallocate.m4                    |   37 +++--------
 config/kernel-fsync.m4                        |   84 ++++---------------------
 config/kernel-lookup-nameidata.m4             |    9 +--
 config/kernel-mkdir-umode-t.m4                |    7 ++-
 config/kernel-shrink.m4                       |   21 +++----
 10 files changed, 62 insertions(+), 149 deletions(-)

diff --git a/config/kernel-bdev-block-device-operations.m4 b/config/kernel-bdev-block-device-operations.m4
index 28c3032..1674af0 100644
--- a/config/kernel-bdev-block-device-operations.m4
+++ b/config/kernel-bdev-block-device-operations.m4
@@ -7,24 +7,21 @@ AC_DEFUN([ZFS_AC_KERNEL_BDEV_BLOCK_DEVICE_OPERATIONS], [
 	EXTRA_KCFLAGS="${NO_UNUSED_BUT_SET_VARIABLE}"
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/blkdev.h>
-	],[
-		int (*blk_open) (struct block_device *, fmode_t) = NULL;
-		int (*blk_release) (struct gendisk *, fmode_t) = NULL;
-		int (*blk_ioctl) (struct block_device *, fmode_t,
-		                  unsigned, unsigned long) = NULL;
-		int (*blk_compat_ioctl) (struct block_device *, fmode_t,
-                                         unsigned, unsigned long) = NULL;
-		struct block_device_operations blk_ops = {
+
+		int blk_open (struct block_device *bdev, fmode_t mode) { return 0; }
+		int blk_release (struct gendisk *g, fmode_t mode) { return 0; }
+		int blk_ioctl (struct block_device *bdev, fmode_t mode,
+		                  unsigned x, unsigned long y) { return 0; }
+		int blk_compat_ioctl (struct block_device * bdev, fmode_t mode,
+                                         unsigned x, unsigned long y) { return 0; }
+		static struct block_device_operations blk_ops __attribute__ ((unused)) = {
 			.open		= blk_open,
 			.release	= blk_release,
 			.ioctl		= blk_ioctl,
 			.compat_ioctl	= blk_compat_ioctl,
 		};
+	],[
 		
-		blk_ops.open(NULL, 0);
-		blk_ops.release(NULL, 0);
-		blk_ops.ioctl(NULL, 0, 0, 0);
-		blk_ops.compat_ioctl(NULL, 0, 0, 0);
 	],[
 		AC_MSG_RESULT(struct block_device)
 		AC_DEFINE(HAVE_BDEV_BLOCK_DEVICE_OPERATIONS, 1,
diff --git a/config/kernel-bio-end-io-t-args.m4 b/config/kernel-bio-end-io-t-args.m4
index ced4861..fe5707a 100644
--- a/config/kernel-bio-end-io-t-args.m4
+++ b/config/kernel-bio-end-io-t-args.m4
@@ -13,11 +13,9 @@ AC_DEFUN([ZFS_AC_KERNEL_BIO_END_IO_T_ARGS], [
 	EXTRA_KCFLAGS="-Werror"
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/bio.h>
+		void wanted_end_io(struct bio * bio, int x) { return; }
 	],[
-		void (*wanted_end_io)(struct bio *, int) = NULL;
-		bio_end_io_t *local_end_io __attribute__ ((unused));
-
-		local_end_io = wanted_end_io;
+		bio_end_io_t *local_end_io __attribute__ ((unused)) = wanted_end_io;
 	],[
 		AC_MSG_RESULT(yes)
 		AC_DEFINE(HAVE_2ARGS_BIO_END_IO_T, 1,
diff --git a/config/kernel-create-nameidata.m4 b/config/kernel-create-nameidata.m4
index 100f077..c779715 100644
--- a/config/kernel-create-nameidata.m4
+++ b/config/kernel-create-nameidata.m4
@@ -5,18 +5,18 @@ AC_DEFUN([ZFS_AC_KERNEL_CREATE_NAMEIDATA], [
 	AC_MSG_CHECKING([whether iops->create() takes struct nameidata])
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/fs.h>
-	],[
 		#ifdef HAVE_MKDIR_UMODE_T
-		int (*inode_create) (struct inode *,struct dentry *,
-		                     umode_t, struct nameidata *) = NULL;
+		int inode_create (struct inode *inode ,struct dentry *dentry,
+		                     umode_t umode, struct nameidata *nidata) { return 0; }
 		#else
-		int (*inode_create) (struct inode *,struct dentry *,
-		                     int, struct nameidata *) = NULL;
+		int inode_create (struct inode *inode,struct dentry *dentry,
+		                     int umode, struct nameidata * nidata) { return 0; }
 		#endif
-		struct inode_operations iops __attribute__ ((unused)) = {
+		static struct inode_operations iops __attribute__ ((unused)) = {
 			.create		= inode_create,
 		};
 	],[
+	],[
 		AC_MSG_RESULT(yes)
 		AC_DEFINE(HAVE_CREATE_NAMEIDATA, 1,
 		          [iops->create() operation takes nameidata])
diff --git a/config/kernel-dentry-operations.m4 b/config/kernel-dentry-operations.m4
index dfbea7d..b89c51d 100644
--- a/config/kernel-dentry-operations.m4
+++ b/config/kernel-dentry-operations.m4
@@ -5,12 +5,12 @@ AC_DEFUN([ZFS_AC_KERNEL_D_REVALIDATE_NAMEIDATA], [
 	AC_MSG_CHECKING([whether dops->d_revalidate() takes struct nameidata])
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/dcache.h>
-	],[
-		int (*revalidate) (struct dentry *, struct nameidata *) = NULL;
-		struct dentry_operations dops __attribute__ ((unused)) = {
+		int revalidate (struct dentry *dentry, struct nameidata *nidata) { return 0; }
+		static struct dentry_operations dops __attribute__ ((unused)) = {
 			.d_revalidate		= revalidate,
 		};
 	],[
+	],[
 		AC_MSG_RESULT(yes)
 		AC_DEFINE(HAVE_D_REVALIDATE_NAMEIDATA, 1,
 		          [dops->d_revalidate() operation takes nameidata])
diff --git a/config/kernel-dirty-inode.m4 b/config/kernel-dirty-inode.m4
index 2ededf1..86e3425 100644
--- a/config/kernel-dirty-inode.m4
+++ b/config/kernel-dirty-inode.m4
@@ -8,11 +8,11 @@ AC_DEFUN([ZFS_AC_KERNEL_DIRTY_INODE_WITH_FLAGS], [
 	AC_MSG_CHECKING([whether sops->dirty_inode() wants flags])
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/fs.h>
+		void dirty_inode (struct inode * a, int b) { return; }
+		static struct super_operations sops __attribute__ ((unused)) = {
+			.dirty_inode = dirty_inode,
+		};
 	],[
-		void (*dirty_inode) (struct inode *, int) = NULL;
-		struct super_operations sops __attribute__ ((unused));
-
-		sops.dirty_inode = dirty_inode;
 	],[
 		AC_MSG_RESULT([yes])
 		AC_DEFINE(HAVE_DIRTY_INODE_WITH_FLAGS, 1,
diff --git a/config/kernel-fallocate.m4 b/config/kernel-fallocate.m4
index 6ac5ae6..0041ef2 100644
--- a/config/kernel-fallocate.m4
+++ b/config/kernel-fallocate.m4
@@ -5,12 +5,12 @@ AC_DEFUN([ZFS_AC_KERNEL_FILE_FALLOCATE], [
 	AC_MSG_CHECKING([whether fops->fallocate() exists])
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/fs.h>
-	],[
-		long (*fallocate) (struct file *, int, loff_t, loff_t) = NULL;
-		struct file_operations fops __attribute__ ((unused)) = {
-			.fallocate = fallocate,
+		long test_fallocate(struct file *file, int mode, loff_t offset, loff_t len) { return 0; }
+		static const struct file_operations fops __attribute__ ((unused)) = {
+			.fallocate = test_fallocate,
 		};
 	],[
+	],[
 		AC_MSG_RESULT(yes)
 		AC_DEFINE(HAVE_FILE_FALLOCATE, 1, [fops->fallocate() exists])
 	],[
@@ -25,34 +25,14 @@ AC_DEFUN([ZFS_AC_KERNEL_INODE_FALLOCATE], [
 	AC_MSG_CHECKING([whether iops->fallocate() exists])
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/fs.h>
-	],[
-		long (*fallocate) (struct inode *, int, loff_t, loff_t) = NULL;
-		struct inode_operations fops __attribute__ ((unused)) = {
-			.fallocate = fallocate,
+		long test_fallocate (struct inode *inode, int mode, loff_t offset, loff_t len) { return 0; }
+		static const struct inode_operations fops __attribute__ ((unused)) = {
+			.fallocate = test_fallocate,
 		};
 	],[
-		AC_MSG_RESULT(yes)
-		AC_DEFINE(HAVE_INODE_FALLOCATE, 1, [fops->fallocate() exists])
-	],[
-		AC_MSG_RESULT(no)
-	])
-])
-
-dnl #
-dnl # PaX Linux 2.6.38 - 3.x API
-dnl #
-AC_DEFUN([ZFS_AC_PAX_KERNEL_FILE_FALLOCATE], [
-	AC_MSG_CHECKING([whether fops->fallocate() exists])
-	ZFS_LINUX_TRY_COMPILE([
-		#include <linux/fs.h>
-	],[
-		long (*fallocate) (struct file *, int, loff_t, loff_t) = NULL;
-		struct file_operations_no_const fops __attribute__ ((unused)) = {
-			.fallocate = fallocate,
-		};
 	],[
 		AC_MSG_RESULT(yes)
-		AC_DEFINE(HAVE_FILE_FALLOCATE, 1, [fops->fallocate() exists])
+		AC_DEFINE(HAVE_INODE_FALLOCATE, 1, [fops->fallocate() exists])
 	],[
 		AC_MSG_RESULT(no)
 	])
@@ -65,5 +45,4 @@ dnl #
 AC_DEFUN([ZFS_AC_KERNEL_FALLOCATE], [
 	ZFS_AC_KERNEL_FILE_FALLOCATE
 	ZFS_AC_KERNEL_INODE_FALLOCATE
-	ZFS_AC_PAX_KERNEL_FILE_FALLOCATE
 ])
diff --git a/config/kernel-fsync.m4 b/config/kernel-fsync.m4
index ca00d93..9ac0c79 100644
--- a/config/kernel-fsync.m4
+++ b/config/kernel-fsync.m4
@@ -4,11 +4,11 @@ dnl #
 AC_DEFUN([ZFS_AC_KERNEL_FSYNC_WITH_DENTRY], [
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/fs.h>
+		int test_fsync (struct file *f, struct dentry *dentry, int x) { return 0; }
+		static const struct file_operations fops __attribute__ ((unused)) = {
+			.fsync = test_fsync,
+		};
 	],[
-		int (*fsync) (struct file *, struct dentry *, int) = NULL;
-		struct file_operations fops __attribute__ ((unused));
-
-		fops.fsync = fsync;
 	],[
 		AC_MSG_RESULT([dentry])
 		AC_DEFINE(HAVE_FSYNC_WITH_DENTRY, 1,
@@ -23,11 +23,11 @@ dnl #
 AC_DEFUN([ZFS_AC_KERNEL_FSYNC_WITHOUT_DENTRY], [
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/fs.h>
+		int test_fsync (struct file *f, int x) { return 0; }
+		static const struct file_operations fops __attribute__ ((unused)) = {
+			.fsync = test_fsync,
+		};
 	],[
-		int (*fsync) (struct file *, int) = NULL;
-		struct file_operations fops __attribute__ ((unused));
-
-		fops.fsync = fsync;
 	],[
 		AC_MSG_RESULT([no dentry])
 		AC_DEFINE(HAVE_FSYNC_WITHOUT_DENTRY, 1,
@@ -42,68 +42,11 @@ dnl #
 AC_DEFUN([ZFS_AC_KERNEL_FSYNC_RANGE], [
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/fs.h>
+		int test_fsync (struct file *f, loff_t a, loff_t b, int c) { return 0; }
+		static const struct file_operations fops __attribute__ ((unused)) = {
+			.fsync = test_fsync,
+		};
 	],[
-		int (*fsync) (struct file *, loff_t, loff_t, int) = NULL;
-		struct file_operations fops __attribute__ ((unused));
-
-		fops.fsync = fsync;
-	],[
-		AC_MSG_RESULT([range])
-		AC_DEFINE(HAVE_FSYNC_RANGE, 1,
-			[fops->fsync() with range])
-	],[
-	])
-])
-
-dnl #
-dnl # PaX Linux 2.6.x - 2.6.34 API
-dnl #
-AC_DEFUN([ZFS_AC_PAX_KERNEL_FSYNC_WITH_DENTRY], [
-	ZFS_LINUX_TRY_COMPILE([
-		#include <linux/fs.h>
-	],[
-		int (*fsync) (struct file *, struct dentry *, int) = NULL;
-		file_operations_no_const fops __attribute__ ((unused));
-
-		fops.fsync = fsync;
-	],[
-		AC_MSG_RESULT([dentry])
-		AC_DEFINE(HAVE_FSYNC_WITH_DENTRY, 1,
-			[fops->fsync() with dentry])
-	],[
-	])
-])
-
-dnl #
-dnl # PaX Linux 2.6.35 - Linux 3.0 API
-dnl #
-AC_DEFUN([ZFS_AC_PAX_KERNEL_FSYNC_WITHOUT_DENTRY], [
-	ZFS_LINUX_TRY_COMPILE([
-		#include <linux/fs.h>
-	],[
-		int (*fsync) (struct file *, int) = NULL;
-		file_operations_no_const fops __attribute__ ((unused));
-
-		fops.fsync = fsync;
-	],[
-		AC_MSG_RESULT([no dentry])
-		AC_DEFINE(HAVE_FSYNC_WITHOUT_DENTRY, 1,
-			[fops->fsync() without dentry])
-	],[
-	])
-])
-
-dnl #
-dnl # PaX Linux 3.1 - 3.x API
-dnl #
-AC_DEFUN([ZFS_AC_PAX_KERNEL_FSYNC_RANGE], [
-	ZFS_LINUX_TRY_COMPILE([
-		#include <linux/fs.h>
-	],[
-		int (*fsync) (struct file *, loff_t, loff_t, int) = NULL;
-		file_operations_no_const fops __attribute__ ((unused));
-
-		fops.fsync = fsync;
 	],[
 		AC_MSG_RESULT([range])
 		AC_DEFINE(HAVE_FSYNC_RANGE, 1,
@@ -117,7 +60,4 @@ AC_DEFUN([ZFS_AC_KERNEL_FSYNC], [
 	ZFS_AC_KERNEL_FSYNC_WITH_DENTRY
 	ZFS_AC_KERNEL_FSYNC_WITHOUT_DENTRY
 	ZFS_AC_KERNEL_FSYNC_RANGE
-	ZFS_AC_PAX_KERNEL_FSYNC_WITH_DENTRY
-	ZFS_AC_PAX_KERNEL_FSYNC_WITHOUT_DENTRY
-	ZFS_AC_PAX_KERNEL_FSYNC_RANGE
 ])
diff --git a/config/kernel-lookup-nameidata.m4 b/config/kernel-lookup-nameidata.m4
index 5e30be4..20b8cca 100644
--- a/config/kernel-lookup-nameidata.m4
+++ b/config/kernel-lookup-nameidata.m4
@@ -5,13 +5,14 @@ AC_DEFUN([ZFS_AC_KERNEL_LOOKUP_NAMEIDATA], [
 	AC_MSG_CHECKING([whether iops->lookup() takes struct nameidata])
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/fs.h>
-	],[
-		struct dentry * (*inode_lookup) (struct inode *,struct dentry *,
-		                     struct nameidata *) = NULL;
-		struct inode_operations iops __attribute__ ((unused)) = {
+		struct dentry * inode_lookup (struct inode * inode,
+			struct dentry * dentry, struct nameidata * nidata)
+			{ return NULL; }
+		static struct inode_operations iops __attribute__ ((unused)) = {
 			.lookup		= inode_lookup,
 		};
 	],[
+	],[
 		AC_MSG_RESULT(yes)
 		AC_DEFINE(HAVE_LOOKUP_NAMEIDATA, 1,
 		          [iops->lookup() operation takes nameidata])
diff --git a/config/kernel-mkdir-umode-t.m4 b/config/kernel-mkdir-umode-t.m4
index dd5d94b..ce8aa8f 100644
--- a/config/kernel-mkdir-umode-t.m4
+++ b/config/kernel-mkdir-umode-t.m4
@@ -10,12 +10,13 @@ AC_DEFUN([ZFS_AC_KERNEL_MKDIR_UMODE_T], [
 	AC_MSG_CHECKING([whether iops->create()/mkdir()/mknod() take umode_t])
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/fs.h>
-	],[
-		int (*mkdir) (struct inode *,struct dentry *,umode_t) = NULL;
-		struct inode_operations iops __attribute__ ((unused)) = {
+		int mkdir (struct inode * inode, struct dentry * dentry, umode_t umode)
+			{ return 0; }
+		static struct inode_operations iops __attribute__ ((unused)) = {
 			.mkdir = mkdir,
 		};
 	],[
+	],[
 		AC_MSG_RESULT(yes)
 		AC_DEFINE(HAVE_MKDIR_UMODE_T, 1,
 		    [iops->create()/mkdir()/mknod() take umode_t])
diff --git a/config/kernel-shrink.m4 b/config/kernel-shrink.m4
index ea748c9..ce4b965 100644
--- a/config/kernel-shrink.m4
+++ b/config/kernel-shrink.m4
@@ -8,15 +8,14 @@ AC_DEFUN([ZFS_AC_KERNEL_SHRINK], [
 	AC_MSG_CHECKING([whether super_block has s_shrink])
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/fs.h>
-	],[
-		int (*shrink)(struct shrinker *, struct shrink_control *sc)
-			__attribute__ ((unused)) = NULL;
-		struct super_block sb __attribute__ ((unused)) = {
+		int shrink(struct shrinker * s, struct shrink_control *sc) { return 0; }
+		static struct super_block sb __attribute__ ((unused)) = {
 			.s_shrink.shrink = shrink,
 			.s_shrink.seeks = DEFAULT_SEEKS,
 			.s_shrink.batch = 0,
 		};
 	],[
+	],[
 		AC_MSG_RESULT(yes)
 		AC_DEFINE(HAVE_SHRINK, 1, [struct super_block has s_shrink])
 
@@ -29,13 +28,12 @@ AC_DEFUN([ZFS_AC_KERNEL_NR_CACHED_OBJECTS], [
 	AC_MSG_CHECKING([whether sops->nr_cached_objects() exists])
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/fs.h>
-	],[
-		int (*nr_cached_objects)(struct super_block *)
-			__attribute__ ((unused)) = NULL;
-		struct super_operations sops __attribute__ ((unused)) = {
+		int nr_cached_objects(struct super_block * sb) { return 0; }
+		static struct super_operations sops __attribute__ ((unused)) = {
 			.nr_cached_objects = nr_cached_objects,
 		};
 	],[
+	],[
 		AC_MSG_RESULT(yes)
 		AC_DEFINE(HAVE_NR_CACHED_OBJECTS, 1,
 			[sops->nr_cached_objects() exists])
@@ -48,13 +46,12 @@ AC_DEFUN([ZFS_AC_KERNEL_FREE_CACHED_OBJECTS], [
 	AC_MSG_CHECKING([whether sops->free_cached_objects() exists])
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/fs.h>
-	],[
-		void (*free_cached_objects)(struct super_block *, int)
-			__attribute__ ((unused)) = NULL;
-		struct super_operations sops __attribute__ ((unused)) = {
+		void free_cached_objects(struct super_block * sb, int x) { return; }
+		static struct super_operations sops __attribute__ ((unused)) = {
 			.free_cached_objects = free_cached_objects,
 		};
 	],[
+	],[
 		AC_MSG_RESULT(yes)
 		AC_DEFINE(HAVE_FREE_CACHED_OBJECTS, 1,
 			[sops->free_cached_objects() exists])
-- 
1.7.10