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 /fs/proc | |
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 'fs/proc')
-rw-r--r-- | fs/proc/task_mmu.c | 30 |
1 files changed, 18 insertions, 12 deletions
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 0137ec4c1368..0a163a4f7764 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c | |||
@@ -122,6 +122,11 @@ struct mem_size_stats | |||
122 | unsigned long private_dirty; | 122 | unsigned long private_dirty; |
123 | }; | 123 | }; |
124 | 124 | ||
125 | __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma) | ||
126 | { | ||
127 | return NULL; | ||
128 | } | ||
129 | |||
125 | static int show_map_internal(struct seq_file *m, void *v, struct mem_size_stats *mss) | 130 | static int show_map_internal(struct seq_file *m, void *v, struct mem_size_stats *mss) |
126 | { | 131 | { |
127 | struct proc_maps_private *priv = m->private; | 132 | struct proc_maps_private *priv = m->private; |
@@ -158,22 +163,23 @@ static int show_map_internal(struct seq_file *m, void *v, struct mem_size_stats | |||
158 | pad_len_spaces(m, len); | 163 | pad_len_spaces(m, len); |
159 | seq_path(m, file->f_vfsmnt, file->f_dentry, "\n"); | 164 | seq_path(m, file->f_vfsmnt, file->f_dentry, "\n"); |
160 | } else { | 165 | } else { |
161 | if (mm) { | 166 | const char *name = arch_vma_name(vma); |
162 | if (vma->vm_start <= mm->start_brk && | 167 | if (!name) { |
168 | if (mm) { | ||
169 | if (vma->vm_start <= mm->start_brk && | ||
163 | vma->vm_end >= mm->brk) { | 170 | vma->vm_end >= mm->brk) { |
164 | pad_len_spaces(m, len); | 171 | name = "[heap]"; |
165 | seq_puts(m, "[heap]"); | 172 | } else if (vma->vm_start <= mm->start_stack && |
166 | } else { | 173 | vma->vm_end >= mm->start_stack) { |
167 | if (vma->vm_start <= mm->start_stack && | 174 | name = "[stack]"; |
168 | vma->vm_end >= mm->start_stack) { | ||
169 | |||
170 | pad_len_spaces(m, len); | ||
171 | seq_puts(m, "[stack]"); | ||
172 | } | 175 | } |
176 | } else { | ||
177 | name = "[vdso]"; | ||
173 | } | 178 | } |
174 | } else { | 179 | } |
180 | if (name) { | ||
175 | pad_len_spaces(m, len); | 181 | pad_len_spaces(m, len); |
176 | seq_puts(m, "[vdso]"); | 182 | seq_puts(m, name); |
177 | } | 183 | } |
178 | } | 184 | } |
179 | seq_putc(m, '\n'); | 185 | seq_putc(m, '\n'); |