From: Bodo Stroesser <[email protected]>
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 <[email protected]>
Signed-off-by: Jeff Dike <[email protected]>
Index: test/arch/um/kernel/skas/include/skas.h
===================================================================
--- test.orig/arch/um/kernel/skas/include/skas.h 2005-09-01 16:03:16.000000000 -0400
+++ test/arch/um/kernel/skas/include/skas.h 2005-09-01 16:21:00.000000000 -0400
@@ -33,7 +33,7 @@
unsigned long len, int r, int w, int x, int done,
void *data);
extern void user_signal(int sig, union uml_pt_regs *regs, int pid);
-extern int new_mm(int from);
+extern int new_mm(int from, unsigned long stack);
extern int start_userspace(unsigned long stub_stack);
extern int copy_context_skas0(unsigned long stack, int pid);
extern void get_skas_faultinfo(int pid, struct faultinfo * fi);
Index: test/arch/um/kernel/skas/mmu.c
===================================================================
--- test.orig/arch/um/kernel/skas/mmu.c 2005-09-01 16:03:16.000000000 -0400
+++ test/arch/um/kernel/skas/mmu.c 2005-09-01 16:21:00.000000000 -0400
@@ -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;
-
- 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 {
+ if(!proc_mm || !ptrace_faultinfo){
+ stack = get_zeroed_page(GFP_KERNEL);
+ if(stack == 0)
+ goto out;
+
/* 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;
dec_mm_counter(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);
}
Index: test/arch/um/kernel/skas/process.c
===================================================================
--- test.orig/arch/um/kernel/skas/process.c 2005-09-01 16:02:46.000000000 -0400
+++ test/arch/um/kernel/skas/process.c 2005-09-01 16:21:00.000000000 -0400
@@ -138,6 +138,8 @@
}
extern int __syscall_stub_start;
+int stub_code_fd = -1;
+__u64 stub_code_offset;
static int userspace_tramp(void *stack)
{
@@ -152,31 +154,31 @@
/* This has a pte, but it can't be mapped in with the usual
* tlb_flush mechanism because this is part of that mechanism
*/
- int fd;
- __u64 offset;
-
- fd = phys_mapping(to_phys(&__syscall_stub_start), &offset);
addr = mmap64((void *) UML_CONFIG_STUB_CODE, page_size(),
- PROT_EXEC, MAP_FIXED | MAP_PRIVATE, fd, offset);
+ PROT_EXEC, MAP_FIXED | MAP_PRIVATE,
+ stub_code_fd, stub_code_offset);
if(addr == MAP_FAILED){
- printk("mapping mmap stub failed, errno = %d\n",
+ printk("mapping stub code failed, errno = %d\n",
errno);
exit(1);
}
if(stack != NULL){
+ int fd;
+ __u64 offset;
+
fd = phys_mapping(to_phys(stack), &offset);
addr = mmap((void *) UML_CONFIG_STUB_DATA, page_size(),
PROT_READ | PROT_WRITE,
MAP_FIXED | MAP_SHARED, fd, offset);
if(addr == MAP_FAILED){
- printk("mapping segfault stack failed, "
+ printk("mapping stub stack failed, "
"errno = %d\n", errno);
exit(1);
}
}
}
- if(!ptrace_faultinfo && (stack != NULL)){
+ if(!ptrace_faultinfo){
unsigned long v = UML_CONFIG_STUB_CODE +
(unsigned long) stub_segv_handler -
(unsigned long) &__syscall_stub_start;
@@ -202,6 +204,10 @@
unsigned long sp;
int pid, status, n, flags;
+ if ( stub_code_fd == -1 )
+ stub_code_fd = phys_mapping(to_phys(&__syscall_stub_start),
+ &stub_code_offset);
+
stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if(stack == MAP_FAILED)
@@ -363,6 +369,53 @@
return pid;
}
+/*
+ * This is used only, if proc_mm is available, while PTRACE_FAULTINFO
+ * isn't. Opening /proc/mm creates a new mm_context, which lacks the stub-pages
+ * Thus, we map them using /proc/mm-fd
+ */
+void map_stub_pages(int fd, unsigned long code,
+ unsigned long data, unsigned long stack)
+{
+ struct proc_mm_op mmop;
+ int n;
+
+ mmop = ((struct proc_mm_op) { .op = MM_MMAP,
+ .u =
+ { .mmap =
+ { .addr = code,
+ .len = PAGE_SIZE,
+ .prot = PROT_EXEC,
+ .flags = MAP_FIXED | MAP_PRIVATE,
+ .fd = stub_code_fd,
+ .offset = stub_code_offset
+ } } });
+ n = os_write_file(fd, &mmop, sizeof(mmop));
+ if(n != sizeof(mmop))
+ panic("map_stub_pages : /proc/mm map for code failed, "
+ "err = %d\n", -n);
+
+ if ( stack ) {
+ __u64 map_offset;
+ int map_fd = phys_mapping(to_phys((void *)stack), &map_offset);
+ mmop = ((struct proc_mm_op)
+ { .op = MM_MMAP,
+ .u =
+ { .mmap =
+ { .addr = data,
+ .len = PAGE_SIZE,
+ .prot = PROT_READ | PROT_WRITE,
+ .flags = MAP_FIXED | MAP_SHARED,
+ .fd = map_fd,
+ .offset = map_offset
+ } } });
+ n = os_write_file(fd, &mmop, sizeof(mmop));
+ if(n != sizeof(mmop))
+ panic("map_stub_pages : /proc/mm map for data failed, "
+ "err = %d\n", -n);
+ }
+}
+
void new_thread(void *stack, void **switch_buf_ptr, void **fork_buf_ptr,
void (*handler)(int))
{
Index: test/arch/um/kernel/skas/process_kern.c
===================================================================
--- test.orig/arch/um/kernel/skas/process_kern.c 2005-09-01 16:02:46.000000000 -0400
+++ test/arch/um/kernel/skas/process_kern.c 2005-09-01 16:21:00.000000000 -0400
@@ -129,7 +129,9 @@
return(0);
}
-int new_mm(int from)
+extern void map_stub_pages(int fd, unsigned long code,
+ unsigned long data, unsigned long stack);
+int new_mm(int from, unsigned long stack)
{
struct proc_mm_op copy;
int n, fd;
@@ -148,6 +150,9 @@
"err = %d\n", -n);
}
+ if(!ptrace_faultinfo)
+ map_stub_pages(fd, CONFIG_STUB_CODE, CONFIG_STUB_DATA, stack);
+
return(fd);
}