[PATCH v2 0/2] x86: fix norandmaps/ADDR_NO_RANDOMIZE

[PATCH v2 0/2] x86: fix norandmaps/ADDR_NO_RANDOMIZE

[Oleg Nesterov]

v2:

	- mention ADDR_NO_RANDOMIZE in subect/changelog

	- add the acks

Oleg.

 arch/x86/mm/mmap.c | 7 +++----
 fs/binfmt_elf.c    | 3 +--
 2 files changed, 4 insertions(+), 6 deletions(-)

[PATCH v2 1/2] x86: fix norandmaps/ADDR_NO_RANDOMIZE

[Oleg Nesterov]

Documentation/admin-guide/kernel-parameters.txt says:

    norandmaps  Don't use address space randomization. Equivalent
                to echo 0 > /proc/sys/kernel/randomize_va_space

but it doesn't work because arch_rnd() which is used to randomize
mm->mmap_base returns a random value unconditionally. And as Kirill
pointed out, ADDR_NO_RANDOMIZE is broken by the same reason.

Just shift the PF_RANDOMIZE check from arch_mmap_rnd() to arch_rnd().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Fixes: 1b028f784e8c ("x86/mm: Introduce mmap_compat_base() for 32-bit mmap()")
Cc: stable <stable@vger.kernel.org> [4.12+]
---
 arch/x86/mm/mmap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index 229d04a..c94df12 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -79,13 +79,13 @@ static int mmap_is_legacy(void)
 
 static unsigned long arch_rnd(unsigned int rndbits)
 {
+	if (!(current->flags & PF_RANDOMIZE))
+		return 0;
 	return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT;
 }
 
 unsigned long arch_mmap_rnd(void)
 {
-	if (!(current->flags & PF_RANDOMIZE))
-		return 0;
 	return arch_rnd(mmap_is_ia32() ? mmap32_rnd_bits : mmap64_rnd_bits);
 }
 
-- 
2.5.0

[tip:x86/urgent] x86: Fix norandmaps/ADDR_NO_RANDOMIZE

[tip-bot for Oleg Nesterov]

Commit-ID:  47ac5484fd961420e5ec0bb5b972fde381f57365
Gitweb:     http://git.kernel.org/tip/47ac5484fd961420e5ec0bb5b972fde381f57365
Author:     Oleg Nesterov <oleg@redhat.com>
AuthorDate: Tue, 15 Aug 2017 17:39:52 +0200
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Wed, 16 Aug 2017 20:32:01 +0200

x86: Fix norandmaps/ADDR_NO_RANDOMIZE

Documentation/admin-guide/kernel-parameters.txt says:

    norandmaps  Don't use address space randomization. Equivalent
                to echo 0 > /proc/sys/kernel/randomize_va_space

but it doesn't work because arch_rnd() which is used to randomize
mm->mmap_base returns a random value unconditionally. And as Kirill
pointed out, ADDR_NO_RANDOMIZE is broken by the same reason.

Just shift the PF_RANDOMIZE check from arch_mmap_rnd() to arch_rnd().

Fixes: 1b028f784e8c ("x86/mm: Introduce mmap_compat_base() for 32-bit mmap()")
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Reviewed-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: stable@vger.kernel.org
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20170815153952.GA1076@redhat.com

---
 arch/x86/mm/mmap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index 229d04a..c94df12 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -79,13 +79,13 @@ static int mmap_is_legacy(void)
 
 static unsigned long arch_rnd(unsigned int rndbits)
 {
+	if (!(current->flags & PF_RANDOMIZE))
+		return 0;
 	return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT;
 }
 
 unsigned long arch_mmap_rnd(void)
 {
-	if (!(current->flags & PF_RANDOMIZE))
-		return 0;
 	return arch_rnd(mmap_is_ia32() ? mmap32_rnd_bits : mmap64_rnd_bits);
 }
 

[PATCH v2 2/2] x86/elf: remove the unnecessary ADDR_NO_RANDOMIZE checks in stack_maxrandom_size() and randomize_stack_top()

[Oleg Nesterov]

PF_RANDOMIZE is set by load_elf_binary() only if ADDR_NO_RANDOMIZE is not
set, no need to re-check after that.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Dmitry Safonov <dsafonov@virtuozzo.com>
---
 arch/x86/mm/mmap.c | 3 +--
 fs/binfmt_elf.c    | 3 +--
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index c94df12..a88cfbf 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -50,8 +50,7 @@ unsigned long tasksize_64bit(void)
 static unsigned long stack_maxrandom_size(unsigned long task_size)
 {
 	unsigned long max = 0;
-	if ((current->flags & PF_RANDOMIZE) &&
-		!(current->personality & ADDR_NO_RANDOMIZE)) {
+	if (current->flags & PF_RANDOMIZE) {
 		max = (-1UL) & __STACK_RND_MASK(task_size == tasksize_32bit());
 		max <<= PAGE_SHIFT;
 	}
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 879ff9c..6466153 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -664,8 +664,7 @@ static unsigned long randomize_stack_top(unsigned long stack_top)
 {
 	unsigned long random_variable = 0;
 
-	if ((current->flags & PF_RANDOMIZE) &&
-		!(current->personality & ADDR_NO_RANDOMIZE)) {
+	if (current->flags & PF_RANDOMIZE) {
 		random_variable = get_random_long();
 		random_variable &= STACK_RND_MASK;
 		random_variable <<= PAGE_SHIFT;
-- 
2.5.0

[tip:x86/urgent] x86/elf: Remove the unnecessary ADDR_NO_RANDOMIZE checks

[tip-bot for Oleg Nesterov]

Commit-ID:  01578e36163cdd0e4fd61d9976de15f13364e26d
Gitweb:     http://git.kernel.org/tip/01578e36163cdd0e4fd61d9976de15f13364e26d
Author:     Oleg Nesterov <oleg@redhat.com>
AuthorDate: Tue, 15 Aug 2017 17:40:11 +0200
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Wed, 16 Aug 2017 20:32:02 +0200

x86/elf: Remove the unnecessary ADDR_NO_RANDOMIZE checks

The ADDR_NO_RANDOMIZE checks in stack_maxrandom_size() and
randomize_stack_top() are not required.

PF_RANDOMIZE is set by load_elf_binary() only if ADDR_NO_RANDOMIZE is not
set, no need to re-check after that.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: stable@vger.kernel.org
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Link: http://lkml.kernel.org/r/20170815154011.GB1076@redhat.com

---
 arch/x86/mm/mmap.c | 3 +--
 fs/binfmt_elf.c    | 3 +--
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index c94df12..a88cfbf 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -50,8 +50,7 @@ unsigned long tasksize_64bit(void)
 static unsigned long stack_maxrandom_size(unsigned long task_size)
 {
 	unsigned long max = 0;
-	if ((current->flags & PF_RANDOMIZE) &&
-		!(current->personality & ADDR_NO_RANDOMIZE)) {
+	if (current->flags & PF_RANDOMIZE) {
 		max = (-1UL) & __STACK_RND_MASK(task_size == tasksize_32bit());
 		max <<= PAGE_SHIFT;
 	}
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 879ff9c..6466153 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -664,8 +664,7 @@ static unsigned long randomize_stack_top(unsigned long stack_top)
 {
 	unsigned long random_variable = 0;
 
-	if ((current->flags & PF_RANDOMIZE) &&
-		!(current->personality & ADDR_NO_RANDOMIZE)) {
+	if (current->flags & PF_RANDOMIZE) {
 		random_variable = get_random_long();
 		random_variable &= STACK_RND_MASK;
 		random_variable <<= PAGE_SHIFT;