diff options
author | Ingo Molnar <mingo@elte.hu> | 2006-06-27 05:53:50 -0400 |
---|---|---|
committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-06-27 20:32:38 -0400 |
commit | e6e5494cb23d1933735ee47cc674ffe1c4afed6f (patch) | |
tree | c8945bb3ae5bec38693d801fb589d22d48d6f8eb /include/linux | |
parent | d5fb34261dcd32c9cb3b28121fdc46308db513a1 (diff) |
[PATCH] vdso: randomize the i386 vDSO by moving it into a vma
Move the i386 VDSO down into a vma and thus randomize it.
Besides the security implications, this feature also helps debuggers, which
can COW a vma-backed VDSO just like a normal DSO and can thus do
single-stepping and other debugging features.
It's good for hypervisors (Xen, VMWare) too, which typically live in the same
high-mapped address space as the VDSO, hence whenever the VDSO is used, they
get lots of guest pagefaults and have to fix such guest accesses up - which
slows things down instead of speeding things up (the primary purpose of the
VDSO).
There's a new CONFIG_COMPAT_VDSO (default=y) option, which provides support
for older glibcs that still rely on a prelinked high-mapped VDSO. Newer
distributions (using glibc 2.3.3 or later) can turn this option off. Turning
it off is also recommended for security reasons: attackers cannot use the
predictable high-mapped VDSO page as syscall trampoline anymore.
There is a new vdso=[0|1] boot option as well, and a runtime
/proc/sys/vm/vdso_enabled sysctl switch, that allows the VDSO to be turned
on/off.
(This version of the VDSO-randomization patch also has working ELF
coredumping, the previous patch crashed in the coredumping code.)
This code is a combined work of the exec-shield VDSO randomization
code and Gerd Hoffmann's hypervisor-centric VDSO patch. Rusty Russell
started this patch and i completed it.
[akpm@osdl.org: cleanups]
[akpm@osdl.org: compile fix]
[akpm@osdl.org: compile fix 2]
[akpm@osdl.org: compile fix 3]
[akpm@osdl.org: revernt MAXMEM change]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Cc: Gerd Hoffmann <kraxel@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/linux')
-rw-r--r-- | include/linux/mm.h | 2 | ||||
-rw-r--r-- | include/linux/sysctl.h | 1 |
2 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index a929ea197e48..ff1fa87df8d0 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h | |||
@@ -1065,5 +1065,7 @@ void drop_slab(void); | |||
1065 | extern int randomize_va_space; | 1065 | extern int randomize_va_space; |
1066 | #endif | 1066 | #endif |
1067 | 1067 | ||
1068 | const char *arch_vma_name(struct vm_area_struct *vma); | ||
1069 | |||
1068 | #endif /* __KERNEL__ */ | 1070 | #endif /* __KERNEL__ */ |
1069 | #endif /* _LINUX_MM_H */ | 1071 | #endif /* _LINUX_MM_H */ |
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h index 349ef908a222..bee12a7a0576 100644 --- a/include/linux/sysctl.h +++ b/include/linux/sysctl.h | |||
@@ -189,6 +189,7 @@ enum | |||
189 | VM_ZONE_RECLAIM_MODE=31, /* reclaim local zone memory before going off node */ | 189 | VM_ZONE_RECLAIM_MODE=31, /* reclaim local zone memory before going off node */ |
190 | VM_ZONE_RECLAIM_INTERVAL=32, /* time period to wait after reclaim failure */ | 190 | VM_ZONE_RECLAIM_INTERVAL=32, /* time period to wait after reclaim failure */ |
191 | VM_PANIC_ON_OOM=33, /* panic at out-of-memory */ | 191 | VM_PANIC_ON_OOM=33, /* panic at out-of-memory */ |
192 | VM_VDSO_ENABLED=34, /* map VDSO into new processes? */ | ||
192 | }; | 193 | }; |
193 | 194 | ||
194 | 195 | ||