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[PATCH] uml: increase granularity of host capability checking

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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>
This commit is contained in:
Bodo Stroesser
2005-09-03 15:57:49 -07:00
committed by Linus Torvalds
parent 60d339f6fe
commit 8b51304ed3
4 changed files with 96 additions and 34 deletions
Download Patch File Download Diff File Expand all files Collapse all files

69
arch/um/kernel/skas/process.c
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@@ -138,6 +138,8 @@ static void handle_trap(int pid, union uml_pt_regs *regs, int local_using_sysemu
}
extern int __syscall_stub_start;
int stub_code_fd = -1;
__u64 stub_code_offset;
static int userspace_tramp(void *stack)
{
@@ -152,31 +154,31 @@ static int userspace_tramp(void *stack)
/* 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 @@ int start_userspace(unsigned long stub_stack)
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 @@ int copy_context_skas0(unsigned long new_stack, int pid)
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))
{