[PATCH] uml: increase granularity of host capability checking
This change enables SKAS0/SKAS3 to work with all combinations of /proc/mm and
PTRACE_FAULTINFO being available or not.
Also it changes the initialization of proc_mm and ptrace_faultinfo slightly,
to ease forcing SKAS0 on a patched host. Forcing UML to run without /proc/mm
or PTRACE_FAULTINFO by cmdline parameter can be implemented with a setup
resetting the related variable.
Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index d232daa..d837223 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -77,23 +77,14 @@
struct mm_struct *cur_mm = current->mm;
struct mm_id *cur_mm_id = &cur_mm->context.skas.id;
struct mm_id *mm_id = &mm->context.skas.id;
- unsigned long stack;
- int from, ret;
+ unsigned long stack = 0;
+ int from, ret = -ENOMEM;
- if(proc_mm){
- if((cur_mm != NULL) && (cur_mm != &init_mm))
- from = cur_mm->context.skas.id.u.mm_fd;
- else from = -1;
+ if(!proc_mm || !ptrace_faultinfo){
+ stack = get_zeroed_page(GFP_KERNEL);
+ if(stack == 0)
+ goto out;
- ret = new_mm(from);
- if(ret < 0){
- printk("init_new_context_skas - new_mm failed, "
- "errno = %d\n", ret);
- return ret;
- }
- mm_id->u.mm_fd = ret;
- }
- else {
/* This zeros the entry that pgd_alloc didn't, needed since
* we are about to reinitialize it, and want mm.nr_ptes to
* be accurate.
@@ -103,20 +94,30 @@
ret = init_stub_pte(mm, CONFIG_STUB_CODE,
(unsigned long) &__syscall_stub_start);
if(ret)
- goto out;
-
- ret = -ENOMEM;
- stack = get_zeroed_page(GFP_KERNEL);
- if(stack == 0)
- goto out;
- mm_id->stack = stack;
+ goto out_free;
ret = init_stub_pte(mm, CONFIG_STUB_DATA, stack);
if(ret)
goto out_free;
mm->nr_ptes--;
+ }
+ mm_id->stack = stack;
+ if(proc_mm){
+ if((cur_mm != NULL) && (cur_mm != &init_mm))
+ from = cur_mm_id->u.mm_fd;
+ else from = -1;
+
+ ret = new_mm(from, stack);
+ if(ret < 0){
+ printk("init_new_context_skas - new_mm failed, "
+ "errno = %d\n", ret);
+ goto out_free;
+ }
+ mm_id->u.mm_fd = ret;
+ }
+ else {
if((cur_mm != NULL) && (cur_mm != &init_mm))
mm_id->u.pid = copy_context_skas0(stack,
cur_mm_id->u.pid);
@@ -126,7 +127,8 @@
return 0;
out_free:
- free_page(mm_id->stack);
+ if(mm_id->stack != 0)
+ free_page(mm_id->stack);
out:
return ret;
}
@@ -137,8 +139,10 @@
if(proc_mm)
os_close_file(mmu->id.u.mm_fd);
- else {
+ else
os_kill_ptraced_process(mmu->id.u.pid, 1);
+
+ if(!proc_mm || !ptrace_faultinfo){
free_page(mmu->id.stack);
free_page(mmu->last_page_table);
}