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From: Willy Tarreau <w@1wt.eu>
To: linux-kernel@vger.kernel.org, stable@kernel.org,
	stable-review@kernel.org
Cc: Tavis Ormandy <taviso@google.com>, Kees Cook <kees@ubuntu.com>,
	Robert Swiecki <swiecki@google.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Greg Kroah-Hartman <gregkh@suse.de>, Willy Tarreau <w@1wt.eu>
Subject: [PATCH 23/23] install_special_mapping skips security_file_mmap check.
Date: Mon, 07 Feb 2011 00:23:15 +0100	[thread overview]
Message-ID: <20110206232253.505982241@pcw.home.local> (raw)
In-Reply-To: <4beed4da27f06efb2c13d6ed48850634@local>

2.6.27.58-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Tavis Ormandy <taviso@cmpxchg8b.com>

commit 462e635e5b73ba9a4c03913b77138cd57ce4b050 upstream.

The install_special_mapping routine (used, for example, to setup the
vdso) skips the security check before insert_vm_struct, allowing a local
attacker to bypass the mmap_min_addr security restriction by limiting
the available pages for special mappings.

bprm_mm_init() also skips the check, and although I don't think this can
be used to bypass any restrictions, I don't see any reason not to have
the security check.

  $ uname -m
  x86_64
  $ cat /proc/sys/vm/mmap_min_addr
  65536
  $ cat install_special_mapping.s
  section .bss
      resb BSS_SIZE
  section .text
      global _start
      _start:
          mov     eax, __NR_pause
          int     0x80
  $ nasm -D__NR_pause=29 -DBSS_SIZE=0xfffed000 -f elf -o install_special_mapping.o install_special_mapping.s
  $ ld -m elf_i386 -Ttext=0x10000 -Tbss=0x11000 -o install_special_mapping install_special_mapping.o
  $ ./install_special_mapping &
  [1] 14303
  $ cat /proc/14303/maps
  0000f000-00010000 r-xp 00000000 00:00 0                                  [vdso]
  00010000-00011000 r-xp 00001000 00:19 2453665                            /home/taviso/install_special_mapping
  00011000-ffffe000 rwxp 00000000 00:00 0                                  [stack]

It's worth noting that Red Hat are shipping with mmap_min_addr set to
4096.

Signed-off-by: Tavis Ormandy <taviso@google.com>
Acked-by: Kees Cook <kees@ubuntu.com>
Acked-by: Robert Swiecki <swiecki@google.com>
[ Changed to not drop the error code - akpm ]
Reviewed-by: James Morris <jmorris@namei.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Willy Tarreau <w@1wt.eu>

---
 fs/exec.c |    5 +++++
 mm/mmap.c |   16 ++++++++++++----
 2 files changed, 17 insertions(+), 4 deletions(-)

Index: longterm-2.6.27/fs/exec.c
===================================================================
--- longterm-2.6.27.orig/fs/exec.c	2011-01-29 11:22:46.000000000 +0100
+++ longterm-2.6.27/fs/exec.c	2011-01-29 15:36:13.479064083 +0100
@@ -257,6 +257,11 @@
 
 	vma->vm_flags = VM_STACK_FLAGS;
 	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
+
+	err = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1);
+	if (err)
+		goto err;
+
 	err = insert_vm_struct(mm, vma);
 	if (err) {
 		up_write(&mm->mmap_sem);
Index: longterm-2.6.27/mm/mmap.c
===================================================================
--- longterm-2.6.27.orig/mm/mmap.c	2011-01-29 11:22:46.000000000 +0100
+++ longterm-2.6.27/mm/mmap.c	2011-01-29 15:38:47.368066702 +0100
@@ -2253,6 +2253,7 @@
 			    unsigned long addr, unsigned long len,
 			    unsigned long vm_flags, struct page **pages)
 {
+	int ret;
 	struct vm_area_struct *vma;
 
 	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
@@ -2269,14 +2270,21 @@
 	vma->vm_ops = &special_mapping_vmops;
 	vma->vm_private_data = pages;
 
-	if (unlikely(insert_vm_struct(mm, vma))) {
-		kmem_cache_free(vm_area_cachep, vma);
-		return -ENOMEM;
-	}
+	ret = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1);
+	if (ret)
+		goto out;
+
+	ret = insert_vm_struct(mm, vma);
+	if (ret)
+		goto out;
 
 	mm->total_vm += len >> PAGE_SHIFT;
 
 	return 0;
+
+out:
+	kmem_cache_free(vm_area_cachep, vma);
+	return ret;
 }
 
 static DEFINE_MUTEX(mm_all_locks_mutex);



      parent reply	other threads:[~2011-02-06 23:46 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20110206232252.509080428@pcw.home.local>
2011-02-06 23:22 ` [PATCH 00/23] 2.6.27.58-longterm review Willy Tarreau
2011-02-06 23:22   ` [PATCH 01/23] ALSA: hda: Use model=lg quirk for LG P1 Express to enable playback and capture Willy Tarreau
2011-02-06 23:22   ` [PATCH 02/23] ALSA: hda: Use LPIB for Dell Latitude 131L Willy Tarreau
2011-02-06 23:22   ` [PATCH 03/23] ALSA: hda: Use LPIB quirk for Dell Inspiron m101z/1120 Willy Tarreau
2011-02-06 23:22   ` [PATCH 04/23] USB: usb-storage: unusual_devs entry for the Samsung YP-CP3 Willy Tarreau
2011-02-06 23:22   ` [PATCH 05/23] USB: misc: uss720.c: add another vendor/product ID Willy Tarreau
2011-02-06 23:22   ` [PATCH 06/23] HID: hidraw: fix window in hidraw_release Willy Tarreau
2011-02-06 23:22   ` [PATCH 07/23] hwmon: (adm1026) Allow 1 as a valid divider value Willy Tarreau
2011-02-06 23:23   ` [PATCH 08/23] hwmon: (adm1026) Fix setting fan_div Willy Tarreau
2011-02-06 23:23   ` [PATCH 09/23] IB/uverbs: Handle large number of entries in poll CQ Willy Tarreau
2011-02-06 23:23   ` [PATCH 10/23] mv_xor: fix race in tasklet function Willy Tarreau
2011-02-06 23:23   ` [PATCH 11/23] md: fix bug with re-adding of partially recovered device Willy Tarreau
2011-02-06 23:23   ` [PATCH 12/23] NFS: Fix fcntl F_GETLK not reporting some conflicts Willy Tarreau
2011-02-06 23:23   ` [PATCH 13/23] nfsd: Fix possible BUG_ON firing in set_change_info Willy Tarreau
2011-02-06 23:23   ` [PATCH 14/23] PM / Hibernate: Fix PM_POST_* notification with user-space suspend Willy Tarreau
2011-02-06 23:23   ` [PATCH 15/23] posix-cpu-timers: workaround to suppress the problems with mt exec Willy Tarreau
2011-02-06 23:23   ` [PATCH 16/23] sctp: Fix a race between ICMP protocol unreachable and connect() Willy Tarreau
2011-02-06 23:23   ` [PATCH 17/23] sound: Prevent buffer overflow in OSS load_mixer_volumes Willy Tarreau
2011-02-06 23:23   ` [PATCH 18/23] sunrpc: prevent use-after-free on clearing XPT_BUSY Willy Tarreau
2011-02-06 23:23   ` [PATCH 19/23] x86, gcc-4.6: Use gcc -m options when building vdso Willy Tarreau
2011-02-06 23:23   ` [PATCH 20/23] tracing: Fix panic when lseek() called on "trace" opened for writing Willy Tarreau
2011-02-14 23:14     ` [Stable-review] " Ben Hutchings
2011-02-15  1:33       ` Steven Rostedt
2011-02-15  1:38         ` Ben Hutchings
2011-02-15  2:01           ` Steven Rostedt
2011-02-15  5:39       ` Willy Tarreau
2011-02-06 23:23   ` [PATCH 21/23] hvc_console: Fix race between hvc_close and hvc_remove Willy Tarreau
2011-02-07 21:16     ` Anton Blanchard
2011-02-07 22:11       ` Willy Tarreau
2011-02-06 23:23   ` [PATCH 22/23] hvc_console: Fix race between hvc_close and hvc_remove, again Willy Tarreau
2011-02-06 23:23   ` Willy Tarreau [this message]

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