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um: Remove SKAS3/4 support

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Before we had SKAS0 UML had two modes of operation
TT (tracing thread) and SKAS3/4 (separated kernel address space).
TT was known to be insecure and got removed a long time ago.
SKAS3/4 required a few (3 or 4) patches on the host side which never went
mainline. The last host patch is 10 years old.

With SKAS0 mode (separated kernel address space using 0 host patches),
default since 2005, SKAS3/4 is obsolete and can be removed.

Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Richard Weinberger
2015-03-18 21:31:27 +01:00
parent aaeac66b1a
commit d0b5e15f0c
18 changed files with 145 additions and 811 deletions
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32
arch/um/kernel/ptrace.c
View File

@@ -8,9 +8,6 @@
#include <linux/sched.h>
#include <linux/tracehook.h>
#include <asm/uaccess.h>
#include <skas_ptrace.h>
void user_enable_single_step(struct task_struct *child)
{
@@ -104,35 +101,6 @@ long arch_ptrace(struct task_struct *child, long request,
ret = ptrace_set_thread_area(child, addr, vp);
break;
case PTRACE_FAULTINFO: {
/*
* Take the info from thread->arch->faultinfo,
* but transfer max. sizeof(struct ptrace_faultinfo).
* On i386, ptrace_faultinfo is smaller!
*/
ret = copy_to_user(p, &child->thread.arch.faultinfo,
sizeof(struct ptrace_faultinfo)) ?
-EIO : 0;
break;
}
#ifdef PTRACE_LDT
case PTRACE_LDT: {
struct ptrace_ldt ldt;
if (copy_from_user(&ldt, p, sizeof(ldt))) {
ret = -EIO;
break;
}
/*
* This one is confusing, so just punt and return -EIO for
* now
*/
ret = -EIO;
break;
}
#endif
default:
ret = ptrace_request(child, request, addr, data);
if (ret == -EIO)

31
arch/um/kernel/reboot.c
View File

@@ -15,28 +15,21 @@ void (*pm_power_off)(void);
static void kill_off_processes(void)
{
if (proc_mm)
/*
* FIXME: need to loop over userspace_pids
*/
os_kill_ptraced_process(userspace_pid[0], 1);
else {
struct task_struct *p;
int pid;
struct task_struct *p;
int pid;
read_lock(&tasklist_lock);
for_each_process(p) {
struct task_struct *t;
read_lock(&tasklist_lock);
for_each_process(p) {
struct task_struct *t;
t = find_lock_task_mm(p);
if (!t)
continue;
pid = t->mm->context.id.u.pid;
task_unlock(t);
os_kill_ptraced_process(pid, 1);
}
read_unlock(&tasklist_lock);
t = find_lock_task_mm(p);
if (!t)
continue;
pid = t->mm->context.id.u.pid;
task_unlock(t);
os_kill_ptraced_process(pid, 1);
}
read_unlock(&tasklist_lock);
}
void uml_cleanup(void)

66
arch/um/kernel/skas/mmu.c
View File

@@ -54,35 +54,22 @@ int init_new_context(struct task_struct *task, struct mm_struct *mm)
unsigned long stack = 0;
int ret = -ENOMEM;
if (skas_needs_stub) {
stack = get_zeroed_page(GFP_KERNEL);
if (stack == 0)
goto out;
}
stack = get_zeroed_page(GFP_KERNEL);
if (stack == 0)
goto out;
to_mm->id.stack = stack;
if (current->mm != NULL && current->mm != &init_mm)
from_mm = &current->mm->context;
if (proc_mm) {
ret = new_mm(stack);
if (ret < 0) {
printk(KERN_ERR "init_new_context_skas - "
"new_mm failed, errno = %d\n", ret);
goto out_free;
}
to_mm->id.u.mm_fd = ret;
}
else {
if (from_mm)
to_mm->id.u.pid = copy_context_skas0(stack,
from_mm->id.u.pid);
else to_mm->id.u.pid = start_userspace(stack);
if (from_mm)
to_mm->id.u.pid = copy_context_skas0(stack,
from_mm->id.u.pid);
else to_mm->id.u.pid = start_userspace(stack);
if (to_mm->id.u.pid < 0) {
ret = to_mm->id.u.pid;
goto out_free;
}
if (to_mm->id.u.pid < 0) {
ret = to_mm->id.u.pid;
goto out_free;
}
ret = init_new_ldt(to_mm, from_mm);
@@ -105,9 +92,6 @@ void uml_setup_stubs(struct mm_struct *mm)
{
int err, ret;
if (!skas_needs_stub)
return;
ret = init_stub_pte(mm, STUB_CODE,
(unsigned long) &__syscall_stub_start);
if (ret)
@@ -154,25 +138,19 @@ void destroy_context(struct mm_struct *mm)
{
struct mm_context *mmu = &mm->context;
if (proc_mm)
os_close_file(mmu->id.u.mm_fd);
else {
/*
* If init_new_context wasn't called, this will be
* zero, resulting in a kill(0), which will result in the
* whole UML suddenly dying. Also, cover negative and
* 1 cases, since they shouldn't happen either.
*/
if (mmu->id.u.pid < 2) {
printk(KERN_ERR "corrupt mm_context - pid = %d\n",
mmu->id.u.pid);
return;
}
os_kill_ptraced_process(mmu->id.u.pid, 1);
/*
* If init_new_context wasn't called, this will be
* zero, resulting in a kill(0), which will result in the
* whole UML suddenly dying. Also, cover negative and
* 1 cases, since they shouldn't happen either.
*/
if (mmu->id.u.pid < 2) {
printk(KERN_ERR "corrupt mm_context - pid = %d\n",
mmu->id.u.pid);
return;
}
os_kill_ptraced_process(mmu->id.u.pid, 1);
if (skas_needs_stub)
free_page(mmu->id.stack);
free_page(mmu->id.stack);
free_ldt(mmu);
}

27
arch/um/kernel/skas/process.c
View File

@@ -10,25 +10,6 @@
#include <os.h>
#include <skas.h>
int new_mm(unsigned long stack)
{
int fd, err;
fd = os_open_file("/proc/mm", of_cloexec(of_write(OPENFLAGS())), 0);
if (fd < 0)
return fd;
if (skas_needs_stub) {
err = map_stub_pages(fd, STUB_CODE, STUB_DATA, stack);
if (err) {
os_close_file(fd);
return err;
}
}
return fd;
}
extern void start_kernel(void);
static int __init start_kernel_proc(void *unused)
@@ -55,14 +36,6 @@ int __init start_uml(void)
{
stack_protections((unsigned long) &cpu0_irqstack);
set_sigstack(cpu0_irqstack, THREAD_SIZE);
if (proc_mm) {
userspace_pid[0] = start_userspace(0);
if (userspace_pid[0] < 0) {
printf("start_uml - start_userspace returned %d\n",
userspace_pid[0]);
exit(1);
}
}
init_new_thread_signals();

2
arch/um/kernel/trap.c
View File

@@ -220,7 +220,7 @@ unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user,
panic("Segfault with no mm");
}
if (SEGV_IS_FIXABLE(&fi) || SEGV_MAYBE_FIXABLE(&fi))
if (SEGV_IS_FIXABLE(&fi))
err = handle_page_fault(address, ip, is_write, is_user,
&si.si_code);
else {

10
arch/um/kernel/um_arch.c
View File

@@ -268,7 +268,6 @@ int __init linux_main(int argc, char **argv)
unsigned long stack;
unsigned int i;
int add;
char * mode;
for (i = 1; i < argc; i++) {
if ((i == 1) && (argv[i][0] == ' '))
@@ -291,15 +290,6 @@ int __init linux_main(int argc, char **argv)
/* OS sanity checks that need to happen before the kernel runs */
os_early_checks();
can_do_skas();
if (proc_mm && ptrace_faultinfo)
mode = "SKAS3";
else
mode = "SKAS0";
printf("UML running in %s mode\n", mode);
brk_start = (unsigned long) sbrk(0);
/*