linux-kernel - [PATCH 3.19.y-ckt 08/54] powerpc: standardize mmap

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon,  9 May 2016 17:04:27 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Kees Cook <keescook@...omium.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.19.y-ckt 08/54] powerpc: standardize mmap_rnd() usage

3.19.8-ckt21 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Kees Cook <keescook@...omium.org>

commit ed6322746afb74c2509e2f3a6464182793b16eb9 upstream.

In preparation for splitting out ET_DYN ASLR, this refactors the use of
mmap_rnd() to be used similarly to arm and x86.

(Can mmap ASLR be safely enabled in the legacy mmap case here?  Other
archs use "mm->mmap_base = TASK_UNMAPPED_BASE + random_factor".)

Signed-off-by: Kees Cook <keescook@...omium.org>
Reviewed-by: Ingo Molnar <mingo@...nel.org>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 arch/powerpc/mm/mmap.c | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/arch/powerpc/mm/mmap.c b/arch/powerpc/mm/mmap.c
index cb8bdbe..1ad2299 100644
--- a/arch/powerpc/mm/mmap.c
+++ b/arch/powerpc/mm/mmap.c
@@ -55,19 +55,18 @@ static inline int mmap_is_legacy(void)
 
 static unsigned long mmap_rnd(void)
 {
-	unsigned long rnd = 0;
+	unsigned long rnd;
+
+	/* 8MB for 32bit, 1GB for 64bit */
+	if (is_32bit_task())
+		rnd = (unsigned long)get_random_int() % (1<<(23-PAGE_SHIFT));
+	else
+		rnd = (unsigned long)get_random_int() % (1<<(30-PAGE_SHIFT));
 
-	if (current->flags & PF_RANDOMIZE) {
-		/* 8MB for 32bit, 1GB for 64bit */
-		if (is_32bit_task())
-			rnd = (long)(get_random_int() % (1<<(23-PAGE_SHIFT)));
-		else
-			rnd = (long)(get_random_int() % (1<<(30-PAGE_SHIFT)));
-	}
 	return rnd << PAGE_SHIFT;
 }
 
-static inline unsigned long mmap_base(void)
+static inline unsigned long mmap_base(unsigned long rnd)
 {
 	unsigned long gap = rlimit(RLIMIT_STACK);
 
@@ -76,7 +75,7 @@ static inline unsigned long mmap_base(void)
 	else if (gap > MAX_GAP)
 		gap = MAX_GAP;
 
-	return PAGE_ALIGN(TASK_SIZE - gap - mmap_rnd());
+	return PAGE_ALIGN(TASK_SIZE - gap - rnd);
 }
 
 /*
@@ -85,6 +84,11 @@ static inline unsigned long mmap_base(void)
  */
 void arch_pick_mmap_layout(struct mm_struct *mm)
 {
+	unsigned long random_factor = 0UL;
+
+	if (current->flags & PF_RANDOMIZE)
+		random_factor = mmap_rnd();
+
 	/*
 	 * Fall back to the standard layout if the personality
 	 * bit is set, or if the expected stack growth is unlimited:
@@ -93,7 +97,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
 		mm->mmap_base = TASK_UNMAPPED_BASE;
 		mm->get_unmapped_area = arch_get_unmapped_area;
 	} else {
-		mm->mmap_base = mmap_base();
+		mm->mmap_base = mmap_base(random_factor);
 		mm->get_unmapped_area = arch_get_unmapped_area_topdown;
 	}
 }
-- 
2.7.4