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x86/asm/entry: Move the vsyscall code to arch/x86/entry/vsyscall/

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The vsyscall code is entry code too, so move it to arch/x86/entry/vsyscall/.

Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar
2015-06-03 18:41:06 +02:00
parent 1f57d5d85b
commit 00398a0018
9 changed files with 12 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
arch/x86/kernel/Makefile
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@@ -31,9 +31,6 @@ obj-y += probe_roms.o
obj-$(CONFIG_X86_32) += i386_ksyms_32.o
obj-$(CONFIG_X86_64) += sys_x86_64.o x8664_ksyms_64.o
obj-$(CONFIG_X86_64) += mcount_64.o
obj-y += syscall_$(BITS).o vsyscall_gtod.o
obj-$(CONFIG_IA32_EMULATION) += syscall_32.o
obj-$(CONFIG_X86_VSYSCALL_EMULATION) += vsyscall_64.o vsyscall_emu_64.o
obj-$(CONFIG_X86_ESPFIX64) += espfix_64.o
obj-$(CONFIG_SYSFS) += ksysfs.o
obj-y += bootflag.o e820.o

33
arch/x86/kernel/syscall_32.c
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@@ -1,33 +0,0 @@
/* System call table for i386. */
#include <linux/linkage.h>
#include <linux/sys.h>
#include <linux/cache.h>
#include <asm/asm-offsets.h>
#ifdef CONFIG_IA32_EMULATION
#define SYM(sym, compat) compat
#else
#define SYM(sym, compat) sym
#define ia32_sys_call_table sys_call_table
#define __NR_ia32_syscall_max __NR_syscall_max
#endif
#define __SYSCALL_I386(nr, sym, compat) extern asmlinkage void SYM(sym, compat)(void) ;
#include <asm/syscalls_32.h>
#undef __SYSCALL_I386
#define __SYSCALL_I386(nr, sym, compat) [nr] = SYM(sym, compat),
typedef asmlinkage void (*sys_call_ptr_t)(void);
extern asmlinkage void sys_ni_syscall(void);
__visible const sys_call_ptr_t ia32_sys_call_table[__NR_ia32_syscall_max+1] = {
/*
* Smells like a compiler bug -- it doesn't work
* when the & below is removed.
*/
[0 ... __NR_ia32_syscall_max] = &sys_ni_syscall,
#include <asm/syscalls_32.h>
};

32
arch/x86/kernel/syscall_64.c
View File

@@ -1,32 +0,0 @@
/* System call table for x86-64. */
#include <linux/linkage.h>
#include <linux/sys.h>
#include <linux/cache.h>
#include <asm/asm-offsets.h>
#include <asm/syscall.h>
#define __SYSCALL_COMMON(nr, sym, compat) __SYSCALL_64(nr, sym, compat)
#ifdef CONFIG_X86_X32_ABI
# define __SYSCALL_X32(nr, sym, compat) __SYSCALL_64(nr, sym, compat)
#else
# define __SYSCALL_X32(nr, sym, compat) /* nothing */
#endif
#define __SYSCALL_64(nr, sym, compat) extern asmlinkage void sym(void) ;
#include <asm/syscalls_64.h>
#undef __SYSCALL_64
#define __SYSCALL_64(nr, sym, compat) [nr] = sym,
extern void sys_ni_syscall(void);
asmlinkage const sys_call_ptr_t sys_call_table[__NR_syscall_max+1] = {
/*
* Smells like a compiler bug -- it doesn't work
* when the & below is removed.
*/
[0 ... __NR_syscall_max] = &sys_ni_syscall,
#include <asm/syscalls_64.h>
};

335
arch/x86/kernel/vsyscall_64.c
View File

@@ -1,335 +0,0 @@
/*
* Copyright (c) 2012-2014 Andy Lutomirski <luto@amacapital.net>
*
* Based on the original implementation which is:
* Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE
* Copyright 2003 Andi Kleen, SuSE Labs.
*
* Parts of the original code have been moved to arch/x86/vdso/vma.c
*
* This file implements vsyscall emulation. vsyscalls are a legacy ABI:
* Userspace can request certain kernel services by calling fixed
* addresses. This concept is problematic:
*
* - It interferes with ASLR.
* - It's awkward to write code that lives in kernel addresses but is
* callable by userspace at fixed addresses.
* - The whole concept is impossible for 32-bit compat userspace.
* - UML cannot easily virtualize a vsyscall.
*
* As of mid-2014, I believe that there is no new userspace code that
* will use a vsyscall if the vDSO is present. I hope that there will
* soon be no new userspace code that will ever use a vsyscall.
*
* The code in this file emulates vsyscalls when notified of a page
* fault to a vsyscall address.
*/
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/syscalls.h>
#include <linux/ratelimit.h>
#include <asm/vsyscall.h>
#include <asm/unistd.h>
#include <asm/fixmap.h>
#include <asm/traps.h>
#define CREATE_TRACE_POINTS
#include "vsyscall_trace.h"
static enum { EMULATE, NATIVE, NONE } vsyscall_mode = EMULATE;
static int __init vsyscall_setup(char *str)
{
if (str) {
if (!strcmp("emulate", str))
vsyscall_mode = EMULATE;
else if (!strcmp("native", str))
vsyscall_mode = NATIVE;
else if (!strcmp("none", str))
vsyscall_mode = NONE;
else
return -EINVAL;
return 0;
}
return -EINVAL;
}
early_param("vsyscall", vsyscall_setup);
static void warn_bad_vsyscall(const char *level, struct pt_regs *regs,
const char *message)
{
if (!show_unhandled_signals)
return;
printk_ratelimited("%s%s[%d] %s ip:%lx cs:%lx sp:%lx ax:%lx si:%lx di:%lx\n",
level, current->comm, task_pid_nr(current),
message, regs->ip, regs->cs,
regs->sp, regs->ax, regs->si, regs->di);
}
static int addr_to_vsyscall_nr(unsigned long addr)
{
int nr;
if ((addr & ~0xC00UL) != VSYSCALL_ADDR)
return -EINVAL;
nr = (addr & 0xC00UL) >> 10;
if (nr >= 3)
return -EINVAL;
return nr;
}
static bool write_ok_or_segv(unsigned long ptr, size_t size)
{
/*
* XXX: if access_ok, get_user, and put_user handled
* sig_on_uaccess_error, this could go away.
*/
if (!access_ok(VERIFY_WRITE, (void __user *)ptr, size)) {
siginfo_t info;
struct thread_struct *thread = &current->thread;
thread->error_code = 6; /* user fault, no page, write */
thread->cr2 = ptr;
thread->trap_nr = X86_TRAP_PF;
memset(&info, 0, sizeof(info));
info.si_signo = SIGSEGV;
info.si_errno = 0;
info.si_code = SEGV_MAPERR;
info.si_addr = (void __user *)ptr;
force_sig_info(SIGSEGV, &info, current);
return false;
} else {
return true;
}
}
bool emulate_vsyscall(struct pt_regs *regs, unsigned long address)
{
struct task_struct *tsk;
unsigned long caller;
int vsyscall_nr, syscall_nr, tmp;
int prev_sig_on_uaccess_error;
long ret;
/*
* No point in checking CS -- the only way to get here is a user mode
* trap to a high address, which means that we're in 64-bit user code.
*/
WARN_ON_ONCE(address != regs->ip);
if (vsyscall_mode == NONE) {
warn_bad_vsyscall(KERN_INFO, regs,
"vsyscall attempted with vsyscall=none");
return false;
}
vsyscall_nr = addr_to_vsyscall_nr(address);
trace_emulate_vsyscall(vsyscall_nr);
if (vsyscall_nr < 0) {
warn_bad_vsyscall(KERN_WARNING, regs,
"misaligned vsyscall (exploit attempt or buggy program) -- look up the vsyscall kernel parameter if you need a workaround");
goto sigsegv;
}
if (get_user(caller, (unsigned long __user *)regs->sp) != 0) {
warn_bad_vsyscall(KERN_WARNING, regs,
"vsyscall with bad stack (exploit attempt?)");
goto sigsegv;
}
tsk = current;
/*
* Check for access_ok violations and find the syscall nr.
*
* NULL is a valid user pointer (in the access_ok sense) on 32-bit and
* 64-bit, so we don't need to special-case it here. For all the
* vsyscalls, NULL means "don't write anything" not "write it at
* address 0".
*/
switch (vsyscall_nr) {
case 0:
if (!write_ok_or_segv(regs->di, sizeof(struct timeval)) ||
!write_ok_or_segv(regs->si, sizeof(struct timezone))) {
ret = -EFAULT;
goto check_fault;
}
syscall_nr = __NR_gettimeofday;
break;
case 1:
if (!write_ok_or_segv(regs->di, sizeof(time_t))) {
ret = -EFAULT;
goto check_fault;
}
syscall_nr = __NR_time;
break;
case 2:
if (!write_ok_or_segv(regs->di, sizeof(unsigned)) ||
!write_ok_or_segv(regs->si, sizeof(unsigned))) {
ret = -EFAULT;
goto check_fault;
}
syscall_nr = __NR_getcpu;
break;
}
/*
* Handle seccomp. regs->ip must be the original value.
* See seccomp_send_sigsys and Documentation/prctl/seccomp_filter.txt.
*
* We could optimize the seccomp disabled case, but performance
* here doesn't matter.
*/
regs->orig_ax = syscall_nr;
regs->ax = -ENOSYS;
tmp = secure_computing();
if ((!tmp && regs->orig_ax != syscall_nr) || regs->ip != address) {
warn_bad_vsyscall(KERN_DEBUG, regs,
"seccomp tried to change syscall nr or ip");
do_exit(SIGSYS);
}
regs->orig_ax = -1;
if (tmp)
goto do_ret; /* skip requested */
/*
* With a real vsyscall, page faults cause SIGSEGV. We want to
* preserve that behavior to make writing exploits harder.
*/
prev_sig_on_uaccess_error = current_thread_info()->sig_on_uaccess_error;
current_thread_info()->sig_on_uaccess_error = 1;
ret = -EFAULT;
switch (vsyscall_nr) {
case 0:
ret = sys_gettimeofday(
(struct timeval __user *)regs->di,
(struct timezone __user *)regs->si);
break;
case 1:
ret = sys_time((time_t __user *)regs->di);
break;
case 2:
ret = sys_getcpu((unsigned __user *)regs->di,
(unsigned __user *)regs->si,
NULL);
break;
}
current_thread_info()->sig_on_uaccess_error = prev_sig_on_uaccess_error;
check_fault:
if (ret == -EFAULT) {
/* Bad news -- userspace fed a bad pointer to a vsyscall. */
warn_bad_vsyscall(KERN_INFO, regs,
"vsyscall fault (exploit attempt?)");
/*
* If we failed to generate a signal for any reason,
* generate one here. (This should be impossible.)
*/
if (WARN_ON_ONCE(!sigismember(&tsk->pending.signal, SIGBUS) &&
!sigismember(&tsk->pending.signal, SIGSEGV)))
goto sigsegv;
return true; /* Don't emulate the ret. */
}
regs->ax = ret;
do_ret:
/* Emulate a ret instruction. */
regs->ip = caller;
regs->sp += 8;
return true;
sigsegv:
force_sig(SIGSEGV, current);
return true;
}
/*
* A pseudo VMA to allow ptrace access for the vsyscall page. This only
* covers the 64bit vsyscall page now. 32bit has a real VMA now and does
* not need special handling anymore:
*/
static const char *gate_vma_name(struct vm_area_struct *vma)
{
return "[vsyscall]";
}
static struct vm_operations_struct gate_vma_ops = {
.name = gate_vma_name,
};
static struct vm_area_struct gate_vma = {
.vm_start = VSYSCALL_ADDR,
.vm_end = VSYSCALL_ADDR + PAGE_SIZE,
.vm_page_prot = PAGE_READONLY_EXEC,
.vm_flags = VM_READ | VM_EXEC,
.vm_ops = &gate_vma_ops,
};
struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
{
#ifdef CONFIG_IA32_EMULATION
if (!mm || mm->context.ia32_compat)
return NULL;
#endif
if (vsyscall_mode == NONE)
return NULL;
return &gate_vma;
}
int in_gate_area(struct mm_struct *mm, unsigned long addr)
{
struct vm_area_struct *vma = get_gate_vma(mm);
if (!vma)
return 0;
return (addr >= vma->vm_start) && (addr < vma->vm_end);
}
/*
* Use this when you have no reliable mm, typically from interrupt
* context. It is less reliable than using a task's mm and may give
* false positives.
*/
int in_gate_area_no_mm(unsigned long addr)
{
return vsyscall_mode != NONE && (addr & PAGE_MASK) == VSYSCALL_ADDR;
}
void __init map_vsyscall(void)
{
extern char __vsyscall_page;
unsigned long physaddr_vsyscall = __pa_symbol(&__vsyscall_page);
if (vsyscall_mode != NONE)
__set_fixmap(VSYSCALL_PAGE, physaddr_vsyscall,
vsyscall_mode == NATIVE
? PAGE_KERNEL_VSYSCALL
: PAGE_KERNEL_VVAR);
BUILD_BUG_ON((unsigned long)__fix_to_virt(VSYSCALL_PAGE) !=
(unsigned long)VSYSCALL_ADDR);
}

37
arch/x86/kernel/vsyscall_emu_64.S
View File

@@ -1,37 +0,0 @@
/*
* vsyscall_emu_64.S: Vsyscall emulation page
*
* Copyright (c) 2011 Andy Lutomirski
*
* Subject to the GNU General Public License, version 2
*/
#include <linux/linkage.h>
#include <asm/irq_vectors.h>
#include <asm/page_types.h>
#include <asm/unistd_64.h>
__PAGE_ALIGNED_DATA
.globl __vsyscall_page
.balign PAGE_SIZE, 0xcc
.type __vsyscall_page, @object
__vsyscall_page:
mov $__NR_gettimeofday, %rax
syscall
ret
.balign 1024, 0xcc
mov $__NR_time, %rax
syscall
ret
.balign 1024, 0xcc
mov $__NR_getcpu, %rax
syscall
ret
.balign 4096, 0xcc
.size __vsyscall_page, 4096

70
arch/x86/kernel/vsyscall_gtod.c
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@@ -1,70 +0,0 @@
/*
* Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE
* Copyright 2003 Andi Kleen, SuSE Labs.
*
* Modified for x86 32 bit architecture by
* Stefani Seibold <stefani@seibold.net>
* sponsored by Rohde & Schwarz GmbH & Co. KG Munich/Germany
*
* Thanks to hpa@transmeta.com for some useful hint.
* Special thanks to Ingo Molnar for his early experience with
* a different vsyscall implementation for Linux/IA32 and for the name.
*
*/
#include <linux/timekeeper_internal.h>
#include <asm/vgtod.h>
#include <asm/vvar.h>
DEFINE_VVAR(struct vsyscall_gtod_data, vsyscall_gtod_data);
void update_vsyscall_tz(void)
{
vsyscall_gtod_data.tz_minuteswest = sys_tz.tz_minuteswest;
vsyscall_gtod_data.tz_dsttime = sys_tz.tz_dsttime;
}
void update_vsyscall(struct timekeeper *tk)
{
struct vsyscall_gtod_data *vdata = &vsyscall_gtod_data;
gtod_write_begin(vdata);
/* copy vsyscall data */
vdata->vclock_mode = tk->tkr_mono.clock->archdata.vclock_mode;
vdata->cycle_last = tk->tkr_mono.cycle_last;
vdata->mask = tk->tkr_mono.mask;
vdata->mult = tk->tkr_mono.mult;
vdata->shift = tk->tkr_mono.shift;
vdata->wall_time_sec = tk->xtime_sec;
vdata->wall_time_snsec = tk->tkr_mono.xtime_nsec;
vdata->monotonic_time_sec = tk->xtime_sec
+ tk->wall_to_monotonic.tv_sec;
vdata->monotonic_time_snsec = tk->tkr_mono.xtime_nsec
+ ((u64)tk->wall_to_monotonic.tv_nsec
<< tk->tkr_mono.shift);
while (vdata->monotonic_time_snsec >=
(((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
vdata->monotonic_time_snsec -=
((u64)NSEC_PER_SEC) << tk->tkr_mono.shift;
vdata->monotonic_time_sec++;
}
vdata->wall_time_coarse_sec = tk->xtime_sec;
vdata->wall_time_coarse_nsec = (long)(tk->tkr_mono.xtime_nsec >>
tk->tkr_mono.shift);
vdata->monotonic_time_coarse_sec =
vdata->wall_time_coarse_sec + tk->wall_to_monotonic.tv_sec;
vdata->monotonic_time_coarse_nsec =
vdata->wall_time_coarse_nsec + tk->wall_to_monotonic.tv_nsec;
while (vdata->monotonic_time_coarse_nsec >= NSEC_PER_SEC) {
vdata->monotonic_time_coarse_nsec -= NSEC_PER_SEC;
vdata->monotonic_time_coarse_sec++;
}
gtod_write_end(vdata);
}

29
arch/x86/kernel/vsyscall_trace.h
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@@ -1,29 +0,0 @@
#undef TRACE_SYSTEM
#define TRACE_SYSTEM vsyscall
#if !defined(__VSYSCALL_TRACE_H) || defined(TRACE_HEADER_MULTI_READ)
#define __VSYSCALL_TRACE_H
#include <linux/tracepoint.h>
TRACE_EVENT(emulate_vsyscall,
TP_PROTO(int nr),
TP_ARGS(nr),
TP_STRUCT__entry(__field(int, nr)),
TP_fast_assign(
__entry->nr = nr;
),
TP_printk("nr = %d", __entry->nr)
);
#endif
#undef TRACE_INCLUDE_PATH
#define TRACE_INCLUDE_PATH ../../arch/x86/kernel
#define TRACE_INCLUDE_FILE vsyscall_trace
#include <trace/define_trace.h>