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authorIngo Molnar <mingo@elte.hu>2006-06-27 05:53:50 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-27 20:32:38 -0400
commite6e5494cb23d1933735ee47cc674ffe1c4afed6f (patch)
treec8945bb3ae5bec38693d801fb589d22d48d6f8eb /fs/proc
parentd5fb34261dcd32c9cb3b28121fdc46308db513a1 (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.c30
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
125static int show_map_internal(struct seq_file *m, void *v, struct mem_size_stats *mss) 130static 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');