From 7263dda41b5a28ae6566fd126d9b06ada73dd721 Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@linux.intel.com>
Date: Fri, 30 Aug 2013 15:43:03 -0700
Subject: [PATCH 1/2] x86, smap: Handle csum_partial_copy_*_user()
Add SMAP annotations to csum_partial_copy_to/from_user(). These
functions legitimately access user space and thus need to set the AC
flag.
TODO: add explicit checks that the side with the kernel space pointer
really points into kernel space.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/n/tip-2aps0u00eer658fd5xyanan7@git.kernel.org
Cc: <stable@vger.kernel.org> # v3.7+
---
arch/x86/include/asm/checksum_32.h | 22 +++++++++++++++++-----
arch/x86/lib/csum-wrappers_64.c | 12 ++++++++++--
2 files changed, 27 insertions(+), 7 deletions(-)
diff --git a/arch/x86/include/asm/checksum_32.h b/arch/x86/include/asm/checksum_32.h
index 46fc474fd819..f50de6951738 100644
--- a/arch/x86/include/asm/checksum_32.h
+++ b/arch/x86/include/asm/checksum_32.h
@@ -49,9 +49,15 @@ static inline __wsum csum_partial_copy_from_user(const void __user *src,
int len, __wsum sum,
int *err_ptr)
{
+ __wsum ret;
+
might_sleep();
- return csum_partial_copy_generic((__force void *)src, dst,
- len, sum, err_ptr, NULL);
+ stac();
+ ret = csum_partial_copy_generic((__force void *)src, dst,
+ len, sum, err_ptr, NULL);
+ clac();
+
+ return ret;
}
/*
@@ -176,10 +182,16 @@ static inline __wsum csum_and_copy_to_user(const void *src,
int len, __wsum sum,
int *err_ptr)
{
+ __wsum ret;
+
might_sleep();
- if (access_ok(VERIFY_WRITE, dst, len))
- return csum_partial_copy_generic(src, (__force void *)dst,
- len, sum, NULL, err_ptr);
+ if (access_ok(VERIFY_WRITE, dst, len)) {
+ stac();
+ ret = csum_partial_copy_generic(src, (__force void *)dst,
+ len, sum, NULL, err_ptr);
+ clac();
+ return ret;
+ }
if (len)
*err_ptr = -EFAULT;
diff --git a/arch/x86/lib/csum-wrappers_64.c b/arch/x86/lib/csum-wrappers_64.c
index 25b7ae8d058a..7609e0e421ec 100644
--- a/arch/x86/lib/csum-wrappers_64.c
+++ b/arch/x86/lib/csum-wrappers_64.c
@@ -6,6 +6,7 @@
*/
#include <asm/checksum.h>
#include <linux/module.h>
+#include <asm/smap.h>
/**
* csum_partial_copy_from_user - Copy and checksum from user space.
@@ -52,8 +53,10 @@ csum_partial_copy_from_user(const void __user *src, void *dst,
len -= 2;
}
}
+ stac();
isum = csum_partial_copy_generic((__force const void *)src,
dst, len, isum, errp, NULL);
+ clac();
if (unlikely(*errp))
goto out_err;
@@ -82,6 +85,8 @@ __wsum
csum_partial_copy_to_user(const void *src, void __user *dst,
int len, __wsum isum, int *errp)
{
+ __wsum ret;
+
might_sleep();
if (unlikely(!access_ok(VERIFY_WRITE, dst, len))) {
@@ -105,8 +110,11 @@ csum_partial_copy_to_user(const void *src, void __user *dst,
}
*errp = 0;
- return csum_partial_copy_generic(src, (void __force *)dst,
- len, isum, NULL, errp);
+ stac();
+ ret = csum_partial_copy_generic(src, (void __force *)dst,
+ len, isum, NULL, errp);
+ clac();
+ return ret;
}
EXPORT_SYMBOL(csum_partial_copy_to_user);
From bd1c149aa9915b9abb6d83d0f01dfd2ace0680b5 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@ZenIV.linux.org.uk>
Date: Sun, 1 Sep 2013 20:35:01 +0100
Subject: [PATCH 2/2] Introduce [compat_]save_altstack_ex() to unbreak x86 SMAP
For performance reasons, when SMAP is in use, SMAP is left open for an
entire put_user_try { ... } put_user_catch(); block, however, calling
__put_user() in the middle of that block will close SMAP as the
STAC..CLAC constructs intentionally do not nest.
Furthermore, using __put_user() rather than put_user_ex() here is bad
for performance.
Thus, introduce new [compat_]save_altstack_ex() helpers that replace
__[compat_]save_altstack() for x86, being currently the only
architecture which supports put_user_try { ... } put_user_catch().
Reported-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@vger.kernel.org> # v3.8+
Link: http://lkml.kernel.org/n/tip-es5p6y64if71k8p5u08agv9n@git.kernel.org
---
arch/x86/ia32/ia32_signal.c | 2 +-
arch/x86/kernel/signal.c | 6 +++---
include/linux/compat.h | 7 +++++++
include/linux/signal.h | 8 ++++++++
4 files changed, 19 insertions(+), 4 deletions(-)
diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index bccfca68430e..665a730307f2 100644
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -457,7 +457,7 @@ int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
else
put_user_ex(0, &frame->uc.uc_flags);
put_user_ex(0, &frame->uc.uc_link);
- err |= __compat_save_altstack(&frame->uc.uc_stack, regs->sp);
+ compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
if (ksig->ka.sa.sa_flags & SA_RESTORER)
restorer = ksig->ka.sa.sa_restorer;
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index cf913587d4dd..d859eea07db7 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -358,7 +358,7 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig,
else
put_user_ex(0, &frame->uc.uc_flags);
put_user_ex(0, &frame->uc.uc_link);
- err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
+ save_altstack_ex(&frame->uc.uc_stack, regs->sp);
/* Set up to return from userspace. */
restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
@@ -423,7 +423,7 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig,
else
put_user_ex(0, &frame->uc.uc_flags);
put_user_ex(0, &frame->uc.uc_link);
- err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
+ save_altstack_ex(&frame->uc.uc_stack, regs->sp);
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
@@ -490,7 +490,7 @@ static int x32_setup_rt_frame(struct ksignal *ksig,
else
put_user_ex(0, &frame->uc.uc_flags);
put_user_ex(0, &frame->uc.uc_link);
- err |= __compat_save_altstack(&frame->uc.uc_stack, regs->sp);
+ compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
put_user_ex(0, &frame->uc.uc__pad0);
if (ksig->ka.sa.sa_flags & SA_RESTORER) {
diff --git a/include/linux/compat.h b/include/linux/compat.h
index 7f0c1dd09079..ec1aee4aec9c 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -669,6 +669,13 @@ asmlinkage long compat_sys_sigaltstack(const compat_stack_t __user *uss_ptr,
int compat_restore_altstack(const compat_stack_t __user *uss);
int __compat_save_altstack(compat_stack_t __user *, unsigned long);
+#define compat_save_altstack_ex(uss, sp) do { \
+ compat_stack_t __user *__uss = uss; \
+ struct task_struct *t = current; \
+ put_user_ex(ptr_to_compat((void __user *)t->sas_ss_sp), &__uss->ss_sp); \
+ put_user_ex(sas_ss_flags(sp), &__uss->ss_flags); \
+ put_user_ex(t->sas_ss_size, &__uss->ss_size); \
+} while (0);
asmlinkage long compat_sys_sched_rr_get_interval(compat_pid_t pid,
struct compat_timespec __user *interval);
diff --git a/include/linux/signal.h b/include/linux/signal.h
index d897484730c0..2ac423bdb676 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -434,6 +434,14 @@ void signals_init(void);
int restore_altstack(const stack_t __user *);
int __save_altstack(stack_t __user *, unsigned long);
+#define save_altstack_ex(uss, sp) do { \
+ stack_t __user *__uss = uss; \
+ struct task_struct *t = current; \
+ put_user_ex((void __user *)t->sas_ss_sp, &__uss->ss_sp); \
+ put_user_ex(sas_ss_flags(sp), &__uss->ss_flags); \
+ put_user_ex(t->sas_ss_size, &__uss->ss_size); \
+} while (0);
+
#ifdef CONFIG_PROC_FS
struct seq_file;
extern void render_sigset_t(struct seq_file *, const char *, sigset_t *);