/* ptrace.c */
/* By Ross Biro 1/23/92 */
/*
* Pentium III FXSR, SSE support
* Gareth Hughes <gareth@valinux.com>, May 2000
*
* x86-64 port 2000-2002 Andi Kleen
*/
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/security.h>
#include <linux/audit.h>
#include <linux/seccomp.h>
#include <linux/signal.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/processor.h>
#include <asm/i387.h>
#include <asm/debugreg.h>
#include <asm/ldt.h>
#include <asm/desc.h>
#include <asm/proto.h>
#include <asm/ia32.h>
/*
* does not yet catch signals sent when the child dies.
* in exit.c or in signal.c.
*/
/* determines which flags the user has access to. */
/* 1 = access 0 = no access */
#define FLAG_MASK 0x44dd5UL
/* set's the trap flag. */
#define TRAP_FLAG 0x100UL
/*
* eflags and offset of eflags on child stack..
*/
#define EFLAGS offsetof(struct pt_regs, eflags)
#define EFL_OFFSET ((int)(EFLAGS-sizeof(struct pt_regs)))
/*
* this routine will get a word off of the processes privileged stack.
* the offset is how far from the base addr as stored in the TSS.
* this routine assumes that all the privileged stacks are in our
* data space.
*/
static inline unsigned long get_stack_long(struct task_struct *task, int offset)
{
unsigned char *stack;
stack = (unsigned char *)task->thread.rsp0;
stack += offset;
return (*((unsigned long *)stack));
}
static inline struct pt_regs *get_child_regs(struct task_struct *task)
{
struct pt_regs *regs = (void *)task->thread.rsp0;
return regs - 1;
}
/*
* this routine will put a word on the processes privileged stack.
* the offset is how far from the base addr as stored in the TSS.
* this routine assumes that all the privileged stacks are in our
* data space.
*/
static inline long put_stack_long(struct task_struct *task, int offset,
unsigned long data)
{
unsigned char * stack;
stack = (unsigned char *) task->thread.rsp0;
stack += offset;
*(unsigned long *) stack = data;
return 0;
}
#define LDT_SEGMENT 4
unsigned long convert_rip_to_linear(struct task_struct *child, struct pt_regs *regs)
{
unsigned long addr, seg;
addr = regs->rip;
seg = regs->cs & 0xffff;
/*
* We'll assume that the code segments in the GDT
* are all zero-based. That is largely true: the
* TLS segments are used for data, and the PNPBIOS
* and APM bios ones we just ignore here.
*/
if (seg & LDT_SEGMENT) {
u32 *desc;
unsigned long base;
down(&child->mm->context.sem);
desc = child->mm->context.ldt + (seg & ~7);
base = (desc[0] >> 16) | ((desc[1] & 0xff) << 16) | (desc[1] & 0xff000000);
/* 16-bit code segment? */
if (!((desc[1] >> 22) & 1))
addr &= 0xffff;
addr += base;
up(&child->mm->context.sem);
}
return addr;
}
static int is_at_popf(struct task_struct *child, struct pt_regs *regs)
{
int i, copied;
unsigned char opcode[16];
unsigned long addr = convert_rip_to_linear(child, regs);
copied = access_process_vm(child, addr, opcode, sizeof(opcode), 0);
for (i = 0; i < copied; i++) {
switch (opcode[i]) {
/* popf */
case 0x9d:
return 1;
/* CHECKME: 64 65 */
/* opcode and address size prefixes */
case 0x66: case 0x67:
continue;
/* irrelevant prefixes (segment overrides and repeats) */
case 0x26: case 0x2e:
case 0x36: case 0x3e:
case 0x64: case 0x65:
case 0xf0: case 0xf2: case 0xf3:
continue;
/* REX prefixes */
case 0x40 ... 0x4f:
continue;
/* CHECKME: f0, f2, f3 */
/*
* pushf: NOTE! We should probably not let
* the user see the TF bit being set. But
* it's more pain than it's worth to avoid
* it, and a debugger could emulate this
* all in user space if it _really_ cares.
*/
case 0x9c:
default:
return 0;
}
}
return 0;
}
static void set_singlestep(struct task_struct *child)
{
struct pt_regs *regs = get_child_regs(child);
/*
* Always set TIF_SINGLESTEP - this guarantees that
* we single-step system calls etc.. This will also
* cause us to set TF when returning to user mode.
*/
set_tsk_thread_flag(child, TIF_SINGLESTEP);
/*
* If TF was already set, don't do anything else
*/
if (regs->eflags & TRAP_FLAG)
return;
/* Set TF on the kernel stack.. */
regs->eflags |= TRAP_FLAG;
/*
* ..but if TF is changed by the instruction we will trace,
* don't mark it as being "us" that set it, so that we
* won't clear it by hand later.
*
* AK: this is not enough, LAHF and IRET can change TF in user space too.
*/
if (is_at_popf(child, regs))
return;
child->ptrace |= PT_DTRACE;
}
static void clear_singlestep(struct task_struct *child)
{
/* Always clear TIF_SINGLESTEP... */
clear_tsk_thread_flag(child, TIF_SINGLESTEP);
/* But touch TF only if it was set by us.. */
if (child->ptrace & PT_DTRACE) {
struct pt_regs *regs = get_child_regs(child);
regs->eflags &= ~TRAP_FLAG;
child->ptrace &= ~PT_DTRACE;
}
}
/*
* Called by kernel/ptrace.c when detaching..
*
* Make sure the single step bit is not set.
*/
void ptrace_disable(struct task_struct *child)
{
clear_singlestep(child);
}
static int putreg(struct task_struct *child,
unsigned long regno, unsigned long value)
{
unsigned long tmp;
/* Some code in the 64bit emulation may not be 64bit clean.
Don't take any chances. */
if (test_tsk_thread_flag(child, TIF_IA32))
value &= 0xffffffff;
switch (regno) {
case offsetof(struct user_regs_struct,fs):
if (value && (value & 3) != 3)
return -EIO;
child->thread.fsindex = value & 0xffff;
return 0;
case offsetof(struct user_regs_struct,gs):
if (value && (value & 3) != 3)
return -EIO;
child->thread.gsindex = value & 0xffff;
return 0;
case offsetof(struct user_regs_struct,ds):
if (value && (value & 3) != 3)
return -EIO;
child->thread.ds = value & 0xffff;
return 0;
case offsetof(struct user_regs_struct,es):
if (value && (value & 3) != 3)
return -EIO;
child->thread.es = value & 0xffff;
return 0;
case offsetof(struct user_regs_struct,ss):
if ((value & 3) != 3)
return -EIO;
value &= 0xffff;
return 0;
case offsetof(struct user_regs_struct,fs_base):
if (value >= TASK_SIZE_OF(child))
return -EIO;
child->thread.fs = value;
return 0;
case offsetof(struct user_regs_struct,gs_base):
if (value >= TASK_SIZE_OF(child))
return -EIO;
child->thread.gs = value;
return 0;
case offsetof(struct user_regs_struct, eflags):
value &= FLAG_MASK;
tmp = get_stack_long(child, EFL_OFFSET);
tmp &= ~FLAG_MASK;
value |= tmp;
break;
case offsetof(struct user_regs_struct,cs):
if ((value & 3) != 3)
return -EIO;
value &= 0xffff;
break;
case offsetof(struct user_regs_struct, rip):
/* Check if the new RIP address is canonical */
if (value >= TASK_SIZE_OF(child))
return -EIO;
break;
}
put_stack_long(child, regno - sizeof(struct pt_regs), value);
return 0;
}
static unsigned long getreg(struct task_struct *child, unsigned long regno)
{
unsigned long val;
switch (regno) {
case offsetof(struct user_regs_struct, fs):
return child->thread.fsindex;
case offsetof(struct user_regs_struct, gs):
return child->thread.gsindex;
case offsetof(struct user_regs_struct, ds):
return child->thread.ds;
case offsetof(struct user_regs_struct, es):
return child->thread.es;
case offsetof(struct user_regs_struct, fs_base):
return child->thread.fs;
case offsetof(struct user_regs_struct, gs_base):
return child->thread.gs;
default:
regno = regno - sizeof(struct pt_regs);
val = get_stack_long(child, regno);
if (test_tsk_thread_flag(child, TIF_IA32))
val &= 0xffffffff;
return val;
}
}
asmlinkage long sys_ptrace(long request, long pid, unsigned long addr, long data)
{
struct task_struct *child;
long i, ret;
unsigned ui;
/* This lock_kernel fixes a subtle race with suid exec */
lock_kernel();
ret = -EPERM;
if (request == PTRACE_TRACEME) {
/* are we already being traced? */
if (current->ptrace & PT_PTRACED)
goto out;
ret = security_ptrace(current->parent, current);
if (ret)
goto out;
/* set the ptrace bit in the process flags. */
current->ptrace |= PT_PTRACED;
ret = 0;
goto out;
}
ret = -ESRCH;
read_lock(&tasklist_lock);
child = find_task_by_pid(pid);
if (child)
get_task_struct(child);
read_unlock(&tasklist_lock);
if (!child)
goto out;
ret = -EPERM;
if (pid == 1) /* you may not mess with init */
goto out_tsk;
if (request == PTRACE_ATTACH) {
ret = ptrace_attach(child);
goto out_tsk;
}
ret = ptrace_check_attach(child, request == PTRACE_KILL);
if (ret < 0)
goto out_tsk;
switch (request) {
/* when I and D space are separate, these will need to be fixed. */
case PTRACE_PEEKTEXT: /* read word at location addr. */
case PTRACE_PEEKDATA: {
unsigned long tmp;
int copied;
copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
ret = -EIO;
if (copied != sizeof(tmp))
break;
ret = put_user(tmp,(unsigned long __user *) data);
break;
}
/* read the word at location addr in the USER area. */
case PTRACE_PEEKUSR: {
unsigned long tmp;
ret = -EIO;
if ((addr & 7) ||
addr > sizeof(struct user) - 7)
break;
switch (addr) {
case 0 ... sizeof(struct user_regs_struct) - sizeof(long):
tmp = getreg(child, addr);
break;
case offsetof(struct user, u_debugreg[0]):
tmp = child->thread.debugreg0;
break;
case offsetof(struct user, u_debugreg[1]):
tmp = child->thread.debugreg1;
break;
case offsetof(struct user, u_debugreg[2]):
tmp = child->thread.debugreg2;
break;
case offsetof(struct user, u_debugreg[3]):
tmp = child->thread.debugreg3;
break;
case offsetof(struct user, u_debugreg[6]):
tmp = child->thread.debugreg6;
break;
case offsetof(struct user, u_debugreg[7]):
tmp = child->thread.debugreg7;
break;
default:
tmp = 0;
break;
}
ret = put_user(tmp,(unsigned long __user *) data);
break;
}
/* when I and D space are separate, this will have to be fixed. */
case PTRACE_POKETEXT: /* write the word at location addr. */
case PTRACE_POKEDATA:
ret = 0;
if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
break;
ret = -EIO;
break;
case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
{
int dsize = test_tsk_thread_flag(child, TIF_IA32) ? 3 : 7;
ret = -EIO;
if ((addr & 7) ||
addr > sizeof(struct user) - 7)
break;
switch (addr) {
case 0 ... sizeof(struct user_regs_struct) - sizeof(long):
ret = putreg(child, addr, data);
break;
/* Disallows to set a breakpoint into the vsyscall */
case offsetof(struct user, u_debugreg[0]):
if (data >= TASK_SIZE_OF(child) - dsize) break;
child->thread.debugreg0 = data;
ret = 0;
break;
case offsetof(struct user, u_debugreg[1]):
if (data >= TASK_SIZE_OF(child) - dsize) break;
child->thread.debugreg1 = data;
ret = 0;
break;
case offsetof(struct user, u_debugreg[2]):
if (data >= TASK_SIZE_OF(child) - dsize) break;
child->thread.debugreg2 = data;
ret = 0;
break;
case offsetof(struct user, u_debugreg[3]):
if (data >= TASK_SIZE_OF(child) - dsize) break;
child->thread.debugreg3 = data;
ret = 0;
break;
case offsetof(struct user, u_debugreg[6]):
if (data >> 32)
break;
child->thread.debugreg6 = data;
ret = 0;
break;
case offsetof(struct user, u_debugreg[7]):
/* See arch/i386/kernel/ptrace.c for an explanation of
* this awkward check.*/
data &= ~DR_CONTROL_RESERVED;
for(i=0; i<4; i++)
if ((0x5454 >> ((data >> (16 + 4*i)) & 0xf)) & 1)
break;
if (i == 4) {
child->thread.debugreg7 = data;
ret = 0;
}
break;
}
break;
}
case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
case PTRACE_CONT: /* restart after signal. */
ret = -EIO;
if (!valid_signal(data))
break;
if (request == PTRACE_SYSCALL)
set_tsk_thread_flag(child,TIF_SYSCALL_TRACE);
else
clear_tsk_thread_flag(child,TIF_SYSCALL_TRACE);
clear_tsk_thread_flag(child, TIF_SINGLESTEP);
child->exit_code = data;
/* make sure the single step bit is not set. */
clear_singlestep(child);
wake_up_process(child);
ret = 0;
break;
#ifdef CONFIG_IA32_EMULATION
/* This makes only sense with 32bit programs. Allow a
64bit debugger to fully examine them too. Better
don't use it against 64bit processes, use
PTRACE_ARCH_PRCTL instead. */
case PTRACE_SET_THREAD_AREA: {
struct user_desc __user *p;
int old;
p = (struct user_desc __user *)data;
get_user(old, &p->entry_number);
put_user(addr, &p->entry_number);
ret = do_set_thread_area(&child->thread, p);
put_user(old, &p->entry_number);
break;
case PTRACE_GET_THREAD_AREA:
p = (struct user_desc __user *)data;
get_user(old, &p->entry_number);
put_user(addr, &p->entry_number);
ret = do_get_thread_area(&child->thread, p);
put_user(old, &p->entry_number);
break;
}
#endif
/* normal 64bit interface to access TLS data.
Works just like arch_prctl, except that the arguments
are reversed. */
case PTRACE_ARCH_PRCTL:
ret = do_arch_prctl(child, data, addr);
break;
/*
* make the child exit. Best I can do is send it a sigkill.
* perhaps it should be put in the status that it wants to
* exit.
*/
case PTRACE_KILL:
ret = 0;
if (child->exit_state == EXIT_ZOMBIE) /* already dead */
break;
clear_tsk_thread_flag(child, TIF_SINGLESTEP);
child->exit_code = SIGKILL;
/* make sure the single step bit is not set. */
clear_singlestep(child);
wake_up_process(child);
break;
case PTRACE_SINGLESTEP: /* set the trap flag. */
ret = -EIO;
if (!valid_signal(data))
break;
clear_tsk_thread_flag(child,TIF_SYSCALL_TRACE);
set_singlestep(child);
child->exit_code = data;
/* give it a chance to run. */
wake_up_process(child);
ret = 0;
break;
case PTRACE_DETACH:
/* detach a process that was attached. */
ret = ptrace_detach(child, data);
break;
case PTRACE_GETREGS: { /* Get all gp regs from the child. */
if (!access_ok(VERIFY_WRITE, (unsigned __user *)data,
sizeof(struct user_regs_struct))) {
ret = -EIO;
break;
}
ret = 0;
for (ui = 0; ui < sizeof(struct user_regs_struct); ui += sizeof(long)) {
ret |= __put_user(getreg(child, ui),(unsigned long __user *) data);
data += sizeof(long);
}
break;
}
case PTRACE_SETREGS: { /* Set all gp regs in the child. */
unsigned long tmp;
if (!access_ok(VERIFY_READ, (unsigned __user *)data,
sizeof(struct user_regs_struct))) {
ret = -EIO;
break;
}
ret = 0;
for (ui = 0; ui < sizeof(struct user_regs_struct); ui += sizeof(long)) {
ret |= __get_user(tmp, (unsigned long __user *) data);
putreg(child, ui, tmp);
data += sizeof(long);
}
break;
}
case PTRACE_GETFPREGS: { /* Get the child extended FPU state. */
if (!access_ok(VERIFY_WRITE, (unsigned __user *)data,
sizeof(struct user_i387_struct))) {
ret = -EIO;
break;
}
ret = get_fpregs((struct user_i387_struct __user *)data, child);
break;
}
case PTRACE_SETFPREGS: { /* Set the child extended FPU state. */
if (!access_ok(VERIFY_READ, (unsigned __user *)data,
sizeof(struct user_i387_struct))) {
ret = -EIO;
break;
}
set_stopped_child_used_math(child);
ret = set_fpregs(child, (struct user_i387_struct __user *)data);
break;
}
default:
ret = ptrace_request(child, request, addr, data);
break;
}
out_tsk:
put_task_struct(child);
out:
unlock_kernel();
return ret;
}
static void syscall_trace(struct pt_regs *regs)
{
#if 0
printk("trace %s rip %lx rsp %lx rax %d origrax %d caller %lx tiflags %x ptrace %x\n",
current->comm,
regs->rip, regs->rsp, regs->rax, regs->orig_rax, __builtin_return_address(0),
current_thread_info()->flags, current->ptrace);
#endif
ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
? 0x80 : 0));
/*
* this isn't the same as continuing with a signal, but it will do
* for normal use. strace only continues with a signal if the
* stopping signal is not SIGTRAP. -brl
*/
if (current->exit_code) {
send_sig(current->exit_code, current, 1);
current->exit_code = 0;
}
}
asmlinkage void syscall_trace_enter(struct pt_regs *regs)
{
/* do the secure computing check first */
secure_computing(regs->orig_rax);
if (test_thread_flag(TIF_SYSCALL_TRACE)
&& (current->ptrace & PT_PTRACED))
syscall_trace(regs);
if (unlikely(current->audit_context)) {
if (test_thread_flag(TIF_IA32)) {
audit_syscall_entry(current, AUDIT_ARCH_I386,
regs->orig_rax,
regs->rbx, regs->rcx,
regs->rdx, regs->rsi);
} else {
audit_syscall_entry(current, AUDIT_ARCH_X86_64,
regs->orig_rax,
regs->rdi, regs->rsi,
regs->rdx, regs->r10);
}
}
}
asmlinkage void syscall_trace_leave(struct pt_regs *regs)
{
if (unlikely(current->audit_context))
audit_syscall_exit(current, AUDITSC_RESULT(regs->rax), regs->rax);
if ((test_thread_flag(TIF_SYSCALL_TRACE)
|| test_thread_flag(TIF_SINGLESTEP))
&& (current->ptrace & PT_PTRACED))
syscall_trace(regs);
}
