[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>
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60d339f6fe
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@ -33,7 +33,7 @@ extern void *protect(struct mm_id * mm_idp, unsigned long addr,
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unsigned long len, int r, int w, int x, int done,
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void *data);
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extern void user_signal(int sig, union uml_pt_regs *regs, int pid);
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extern int new_mm(int from);
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extern int new_mm(int from, unsigned long stack);
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extern int start_userspace(unsigned long stub_stack);
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extern int copy_context_skas0(unsigned long stack, int pid);
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extern void get_skas_faultinfo(int pid, struct faultinfo * fi);
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@ -77,23 +77,14 @@ int init_new_context_skas(struct task_struct *task, struct mm_struct *mm)
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struct mm_struct *cur_mm = current->mm;
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struct mm_id *cur_mm_id = &cur_mm->context.skas.id;
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struct mm_id *mm_id = &mm->context.skas.id;
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unsigned long stack;
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int from, ret;
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unsigned long stack = 0;
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int from, ret = -ENOMEM;
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if(proc_mm){
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if((cur_mm != NULL) && (cur_mm != &init_mm))
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from = cur_mm->context.skas.id.u.mm_fd;
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else from = -1;
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if(!proc_mm || !ptrace_faultinfo){
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stack = get_zeroed_page(GFP_KERNEL);
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if(stack == 0)
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goto out;
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ret = new_mm(from);
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if(ret < 0){
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printk("init_new_context_skas - new_mm failed, "
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"errno = %d\n", ret);
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return ret;
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}
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mm_id->u.mm_fd = ret;
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}
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else {
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/* This zeros the entry that pgd_alloc didn't, needed since
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* we are about to reinitialize it, and want mm.nr_ptes to
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* be accurate.
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@ -103,20 +94,30 @@ int init_new_context_skas(struct task_struct *task, struct mm_struct *mm)
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ret = init_stub_pte(mm, CONFIG_STUB_CODE,
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(unsigned long) &__syscall_stub_start);
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if(ret)
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goto out;
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ret = -ENOMEM;
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stack = get_zeroed_page(GFP_KERNEL);
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if(stack == 0)
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goto out;
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mm_id->stack = stack;
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goto out_free;
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ret = init_stub_pte(mm, CONFIG_STUB_DATA, stack);
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if(ret)
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goto out_free;
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mm->nr_ptes--;
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}
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mm_id->stack = stack;
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if(proc_mm){
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if((cur_mm != NULL) && (cur_mm != &init_mm))
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from = cur_mm_id->u.mm_fd;
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else from = -1;
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ret = new_mm(from, stack);
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if(ret < 0){
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printk("init_new_context_skas - new_mm failed, "
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"errno = %d\n", ret);
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goto out_free;
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}
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mm_id->u.mm_fd = ret;
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}
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else {
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if((cur_mm != NULL) && (cur_mm != &init_mm))
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mm_id->u.pid = copy_context_skas0(stack,
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cur_mm_id->u.pid);
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@ -126,7 +127,8 @@ int init_new_context_skas(struct task_struct *task, struct mm_struct *mm)
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return 0;
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out_free:
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free_page(mm_id->stack);
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if(mm_id->stack != 0)
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free_page(mm_id->stack);
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out:
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return ret;
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}
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@ -137,8 +139,10 @@ void destroy_context_skas(struct mm_struct *mm)
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if(proc_mm)
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os_close_file(mmu->id.u.mm_fd);
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else {
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else
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os_kill_ptraced_process(mmu->id.u.pid, 1);
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if(!proc_mm || !ptrace_faultinfo){
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free_page(mmu->id.stack);
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free_page(mmu->last_page_table);
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}
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@ -138,6 +138,8 @@ static void handle_trap(int pid, union uml_pt_regs *regs, int local_using_sysemu
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}
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extern int __syscall_stub_start;
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int stub_code_fd = -1;
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__u64 stub_code_offset;
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static int userspace_tramp(void *stack)
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{
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@ -152,31 +154,31 @@ static int userspace_tramp(void *stack)
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/* This has a pte, but it can't be mapped in with the usual
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* tlb_flush mechanism because this is part of that mechanism
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*/
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int fd;
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__u64 offset;
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fd = phys_mapping(to_phys(&__syscall_stub_start), &offset);
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addr = mmap64((void *) UML_CONFIG_STUB_CODE, page_size(),
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PROT_EXEC, MAP_FIXED | MAP_PRIVATE, fd, offset);
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PROT_EXEC, MAP_FIXED | MAP_PRIVATE,
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stub_code_fd, stub_code_offset);
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if(addr == MAP_FAILED){
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printk("mapping mmap stub failed, errno = %d\n",
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printk("mapping stub code failed, errno = %d\n",
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errno);
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exit(1);
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}
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if(stack != NULL){
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int fd;
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__u64 offset;
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fd = phys_mapping(to_phys(stack), &offset);
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addr = mmap((void *) UML_CONFIG_STUB_DATA, page_size(),
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PROT_READ | PROT_WRITE,
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MAP_FIXED | MAP_SHARED, fd, offset);
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if(addr == MAP_FAILED){
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printk("mapping segfault stack failed, "
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printk("mapping stub stack failed, "
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"errno = %d\n", errno);
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exit(1);
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}
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}
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}
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if(!ptrace_faultinfo && (stack != NULL)){
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if(!ptrace_faultinfo){
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unsigned long v = UML_CONFIG_STUB_CODE +
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(unsigned long) stub_segv_handler -
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(unsigned long) &__syscall_stub_start;
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@ -202,6 +204,10 @@ int start_userspace(unsigned long stub_stack)
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unsigned long sp;
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int pid, status, n, flags;
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if ( stub_code_fd == -1 )
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stub_code_fd = phys_mapping(to_phys(&__syscall_stub_start),
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&stub_code_offset);
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stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,
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MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
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if(stack == MAP_FAILED)
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@ -363,6 +369,53 @@ int copy_context_skas0(unsigned long new_stack, int pid)
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return pid;
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}
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/*
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* This is used only, if proc_mm is available, while PTRACE_FAULTINFO
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* isn't. Opening /proc/mm creates a new mm_context, which lacks the stub-pages
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* Thus, we map them using /proc/mm-fd
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*/
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void map_stub_pages(int fd, unsigned long code,
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unsigned long data, unsigned long stack)
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{
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struct proc_mm_op mmop;
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int n;
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mmop = ((struct proc_mm_op) { .op = MM_MMAP,
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.u =
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{ .mmap =
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{ .addr = code,
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.len = PAGE_SIZE,
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.prot = PROT_EXEC,
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.flags = MAP_FIXED | MAP_PRIVATE,
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.fd = stub_code_fd,
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.offset = stub_code_offset
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} } });
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n = os_write_file(fd, &mmop, sizeof(mmop));
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if(n != sizeof(mmop))
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panic("map_stub_pages : /proc/mm map for code failed, "
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"err = %d\n", -n);
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if ( stack ) {
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__u64 map_offset;
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int map_fd = phys_mapping(to_phys((void *)stack), &map_offset);
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mmop = ((struct proc_mm_op)
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{ .op = MM_MMAP,
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.u =
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{ .mmap =
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{ .addr = data,
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.len = PAGE_SIZE,
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.prot = PROT_READ | PROT_WRITE,
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.flags = MAP_FIXED | MAP_SHARED,
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.fd = map_fd,
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.offset = map_offset
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} } });
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n = os_write_file(fd, &mmop, sizeof(mmop));
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if(n != sizeof(mmop))
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panic("map_stub_pages : /proc/mm map for data failed, "
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"err = %d\n", -n);
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}
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}
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void new_thread(void *stack, void **switch_buf_ptr, void **fork_buf_ptr,
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void (*handler)(int))
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{
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@ -129,7 +129,9 @@ int copy_thread_skas(int nr, unsigned long clone_flags, unsigned long sp,
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return(0);
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}
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int new_mm(int from)
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extern void map_stub_pages(int fd, unsigned long code,
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unsigned long data, unsigned long stack);
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int new_mm(int from, unsigned long stack)
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{
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struct proc_mm_op copy;
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int n, fd;
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@ -148,6 +150,9 @@ int new_mm(int from)
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"err = %d\n", -n);
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}
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if(!ptrace_faultinfo)
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map_stub_pages(fd, CONFIG_STUB_CODE, CONFIG_STUB_DATA, stack);
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return(fd);
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}
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