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OpenCloudOS-Kernel/arch/x86/kernel/ptrace.c

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/* By Ross Biro 1/23/92 */
/*
* Pentium III FXSR, SSE support
* Gareth Hughes <gareth@valinux.com>, May 2000
*/
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.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>
/*
* 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].
* Prohibits changing ID(21), VIP(20), VIF(19), VM(17), NT(14), IOPL(12-13), IF(9).
* Also masks reserved bits (31-22, 15, 5, 3, 1).
*/
#define FLAG_MASK 0x00050dd5
static long *pt_regs_access(struct pt_regs *regs, unsigned long regno)
{
BUILD_BUG_ON(offsetof(struct pt_regs, bx) != 0);
if (regno > FS)
--regno;
return &regs->bx + regno;
}
static int putreg(struct task_struct *child,
unsigned long regno, unsigned long value)
{
struct pt_regs *regs = task_pt_regs(child);
regno >>= 2;
switch (regno) {
case GS:
if (value && (value & 3) != 3)
return -EIO;
child->thread.gs = value;
if (child == current)
/*
* The user-mode %gs is not affected by
* kernel entry, so we must update the CPU.
*/
loadsegment(gs, value);
return 0;
case DS:
case ES:
case FS:
if (value && (value & 3) != 3)
return -EIO;
value &= 0xffff;
break;
case SS:
case CS:
if ((value & 3) != 3)
return -EIO;
value &= 0xffff;
break;
case EFL:
value &= FLAG_MASK;
/*
* If the user value contains TF, mark that
* it was not "us" (the debugger) that set it.
* If not, make sure it stays set if we had.
*/
if (value & X86_EFLAGS_TF)
clear_tsk_thread_flag(child, TIF_FORCED_TF);
else if (test_tsk_thread_flag(child, TIF_FORCED_TF))
value |= X86_EFLAGS_TF;
value |= regs->flags & ~FLAG_MASK;
break;
}
*pt_regs_access(regs, regno) = value;
return 0;
}
static unsigned long getreg(struct task_struct *child, unsigned long regno)
{
struct pt_regs *regs = task_pt_regs(child);
unsigned long retval = ~0UL;
regno >>= 2;
switch (regno) {
case EFL:
/*
* If the debugger set TF, hide it from the readout.
*/
retval = regs->flags;
if (test_tsk_thread_flag(child, TIF_FORCED_TF))
retval &= ~X86_EFLAGS_TF;
break;
case GS:
retval = child->thread.gs;
if (child == current)
savesegment(gs, retval);
break;
case DS:
case ES:
case FS:
case SS:
case CS:
retval = 0xffff;
/* fall through */
default:
retval &= *pt_regs_access(regs, regno);
}
return retval;
}
/*
* This function is trivial and will be inlined by the compiler.
* Having it separates the implementation details of debug
* registers from the interface details of ptrace.
*/
static unsigned long ptrace_get_debugreg(struct task_struct *child, int n)
{
switch (n) {
case 0: return child->thread.debugreg0;
case 1: return child->thread.debugreg1;
case 2: return child->thread.debugreg2;
case 3: return child->thread.debugreg3;
case 6: return child->thread.debugreg6;
case 7: return child->thread.debugreg7;
}
return 0;
}
static int ptrace_set_debugreg(struct task_struct *child,
int n, unsigned long data)
{
int i;
if (unlikely(n == 4 || n == 5))
return -EIO;
if (n < 4 && unlikely(data >= TASK_SIZE - 3))
return -EIO;
switch (n) {
case 0: child->thread.debugreg0 = data; break;
case 1: child->thread.debugreg1 = data; break;
case 2: child->thread.debugreg2 = data; break;
case 3: child->thread.debugreg3 = data; break;
case 6:
child->thread.debugreg6 = data;
break;
case 7:
/*
* Sanity-check data. Take one half-byte at once with
* check = (val >> (16 + 4*i)) & 0xf. It contains the
* R/Wi and LENi bits; bits 0 and 1 are R/Wi, and bits
* 2 and 3 are LENi. Given a list of invalid values,
* we do mask |= 1 << invalid_value, so that
* (mask >> check) & 1 is a correct test for invalid
* values.
*
* R/Wi contains the type of the breakpoint /
* watchpoint, LENi contains the length of the watched
* data in the watchpoint case.
*
* The invalid values are:
* - LENi == 0x10 (undefined), so mask |= 0x0f00.
* - R/Wi == 0x10 (break on I/O reads or writes), so
* mask |= 0x4444.
* - R/Wi == 0x00 && LENi != 0x00, so we have mask |=
* 0x1110.
*
* Finally, mask = 0x0f00 | 0x4444 | 0x1110 == 0x5f54.
*
* See the Intel Manual "System Programming Guide",
* 15.2.4
*
* Note that LENi == 0x10 is defined on x86_64 in long
* mode (i.e. even for 32-bit userspace software, but
* 64-bit kernel), so the x86_64 mask value is 0x5454.
* See the AMD manual no. 24593 (AMD64 System Programming)
*/
data &= ~DR_CONTROL_RESERVED;
for (i = 0; i < 4; i++)
if ((0x5f54 >> ((data >> (16 + 4*i)) & 0xf)) & 1)
return -EIO;
child->thread.debugreg7 = data;
if (data)
set_tsk_thread_flag(child, TIF_DEBUG);
else
clear_tsk_thread_flag(child, TIF_DEBUG);
break;
}
return 0;
}
/*
* Called by kernel/ptrace.c when detaching..
*
* Make sure the single step bit is not set.
*/
void ptrace_disable(struct task_struct *child)
{
user_disable_single_step(child);
clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
}
long arch_ptrace(struct task_struct *child, long request, long addr, long data)
{
struct user * dummy = NULL;
int i, ret;
unsigned long __user *datap = (unsigned long __user *)data;
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:
ret = generic_ptrace_peekdata(child, addr, data);
break;
/* read the word at location addr in the USER area. */
case PTRACE_PEEKUSR: {
unsigned long tmp;
ret = -EIO;
if ((addr & 3) || addr < 0 ||
addr > sizeof(struct user) - 3)
break;
tmp = 0; /* Default return condition */
if(addr < FRAME_SIZE*sizeof(long))
tmp = getreg(child, addr);
if(addr >= (long) &dummy->u_debugreg[0] &&
addr <= (long) &dummy->u_debugreg[7]){
addr -= (long) &dummy->u_debugreg[0];
addr = addr >> 2;
tmp = ptrace_get_debugreg(child, addr);
}
ret = put_user(tmp, datap);
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 = generic_ptrace_pokedata(child, addr, data);
break;
case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
ret = -EIO;
if ((addr & 3) || addr < 0 ||
addr > sizeof(struct user) - 3)
break;
if (addr < FRAME_SIZE*sizeof(long)) {
ret = putreg(child, addr, data);
break;
}
/* We need to be very careful here. We implicitly
want to modify a portion of the task_struct, and we
have to be selective about what portions we allow someone
to modify. */
ret = -EIO;
if(addr >= (long) &dummy->u_debugreg[0] &&
addr <= (long) &dummy->u_debugreg[7]){
addr -= (long) &dummy->u_debugreg;
addr = addr >> 2;
ret = ptrace_set_debugreg(child, addr, data);
}
break;
case PTRACE_GETREGS: { /* Get all gp regs from the child. */
if (!access_ok(VERIFY_WRITE, datap, FRAME_SIZE*sizeof(long))) {
ret = -EIO;
break;
}
for ( i = 0; i < FRAME_SIZE*sizeof(long); i += sizeof(long) ) {
__put_user(getreg(child, i), datap);
datap++;
}
ret = 0;
break;
}
case PTRACE_SETREGS: { /* Set all gp regs in the child. */
unsigned long tmp;
if (!access_ok(VERIFY_READ, datap, FRAME_SIZE*sizeof(long))) {
ret = -EIO;
break;
}
for ( i = 0; i < FRAME_SIZE*sizeof(long); i += sizeof(long) ) {
__get_user(tmp, datap);
putreg(child, i, tmp);
datap++;
}
ret = 0;
break;
}
case PTRACE_GETFPREGS: { /* Get the child FPU state. */
if (!access_ok(VERIFY_WRITE, datap,
sizeof(struct user_i387_struct))) {
ret = -EIO;
break;
}
ret = 0;
if (!tsk_used_math(child))
init_fpu(child);
get_fpregs((struct user_i387_struct __user *)data, child);
break;
}
case PTRACE_SETFPREGS: { /* Set the child FPU state. */
if (!access_ok(VERIFY_READ, datap,
sizeof(struct user_i387_struct))) {
ret = -EIO;
break;
}
set_stopped_child_used_math(child);
set_fpregs(child, (struct user_i387_struct __user *)data);
ret = 0;
break;
}
case PTRACE_GETFPXREGS: { /* Get the child extended FPU state. */
if (!access_ok(VERIFY_WRITE, datap,
sizeof(struct user_fxsr_struct))) {
ret = -EIO;
break;
}
if (!tsk_used_math(child))
init_fpu(child);
ret = get_fpxregs((struct user_fxsr_struct __user *)data, child);
break;
}
case PTRACE_SETFPXREGS: { /* Set the child extended FPU state. */
if (!access_ok(VERIFY_READ, datap,
sizeof(struct user_fxsr_struct))) {
ret = -EIO;
break;
}
set_stopped_child_used_math(child);
ret = set_fpxregs(child, (struct user_fxsr_struct __user *)data);
break;
}
case PTRACE_GET_THREAD_AREA:
if (addr < 0)
return -EIO;
ret = do_get_thread_area(child, addr,
(struct user_desc __user *) data);
break;
case PTRACE_SET_THREAD_AREA:
if (addr < 0)
return -EIO;
ret = do_set_thread_area(child, addr,
(struct user_desc __user *) data, 0);
break;
default:
ret = ptrace_request(child, request, addr, data);
break;
}
return ret;
}
void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int error_code)
{
struct siginfo info;
tsk->thread.trap_no = 1;
tsk->thread.error_code = error_code;
memset(&info, 0, sizeof(info));
info.si_signo = SIGTRAP;
info.si_code = TRAP_BRKPT;
/* User-mode ip? */
info.si_addr = user_mode_vm(regs) ? (void __user *) regs->ip : NULL;
/* Send us the fake SIGTRAP */
force_sig_info(SIGTRAP, &info, tsk);
}
/* notification of system call entry/exit
* - triggered by current->work.syscall_trace
*/
__attribute__((regparm(3)))
int do_syscall_trace(struct pt_regs *regs, int entryexit)
{
int is_sysemu = test_thread_flag(TIF_SYSCALL_EMU);
/*
* With TIF_SYSCALL_EMU set we want to ignore TIF_SINGLESTEP for syscall
* interception
*/
int is_singlestep = !is_sysemu && test_thread_flag(TIF_SINGLESTEP);
int ret = 0;
/* do the secure computing check first */
if (!entryexit)
secure_computing(regs->orig_ax);
if (unlikely(current->audit_context)) {
if (entryexit)
audit_syscall_exit(AUDITSC_RESULT(regs->ax),
regs->ax);
/* Debug traps, when using PTRACE_SINGLESTEP, must be sent only
* on the syscall exit path. Normally, when TIF_SYSCALL_AUDIT is
* not used, entry.S will call us only on syscall exit, not
* entry; so when TIF_SYSCALL_AUDIT is used we must avoid
* calling send_sigtrap() on syscall entry.
*
* Note that when PTRACE_SYSEMU_SINGLESTEP is used,
* is_singlestep is false, despite his name, so we will still do
* the correct thing.
*/
else if (is_singlestep)
goto out;
}
if (!(current->ptrace & PT_PTRACED))
goto out;
/* If a process stops on the 1st tracepoint with SYSCALL_TRACE
* and then is resumed with SYSEMU_SINGLESTEP, it will come in
* here. We have to check this and return */
if (is_sysemu && entryexit)
return 0;
/* Fake a debug trap */
if (is_singlestep)
send_sigtrap(current, regs, 0);
if (!test_thread_flag(TIF_SYSCALL_TRACE) && !is_sysemu)
goto out;
/* the 0x80 provides a way for the tracing parent to distinguish
between a syscall stop and SIGTRAP delivery */
/* Note that the debugger could change the result of test_thread_flag!*/
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;
}
ret = is_sysemu;
out:
if (unlikely(current->audit_context) && !entryexit)
audit_syscall_entry(AUDIT_ARCH_I386, regs->orig_ax,
regs->bx, regs->cx, regs->dx, regs->si);
if (ret == 0)
return 0;
regs->orig_ax = -1; /* force skip of syscall restarting */
if (unlikely(current->audit_context))
audit_syscall_exit(AUDITSC_RESULT(regs->ax), regs->ax);
return 1;
}
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