ptrace.c

Go to the documentation of this file.

/*
 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include <linux/audit.h>
#include <linux/ptrace.h>
#include <linux/sched.h>
#include <linux/tracehook.h>
#include <asm/uaccess.h>
#include <skas_ptrace.h>



void user_enable_single_step(struct task_struct *child)
{
    child->ptrace |= PT_DTRACE;
    child->thread.singlestep_syscall = 0;

#ifdef SUBARCH_SET_SINGLESTEPPING
    SUBARCH_SET_SINGLESTEPPING(child, 1);
#endif
}

void user_disable_single_step(struct task_struct *child)
{
    child->ptrace &= ~PT_DTRACE;
    child->thread.singlestep_syscall = 0;

#ifdef SUBARCH_SET_SINGLESTEPPING
    SUBARCH_SET_SINGLESTEPPING(child, 0);
#endif
}

/*
 * Called by kernel/ptrace.c when detaching..
 */
void ptrace_disable(struct task_struct *child)
{
    user_disable_single_step(child);
}

extern int peek_user(struct task_struct * child, long addr, long data);
extern int poke_user(struct task_struct * child, long addr, long data);

long arch_ptrace(struct task_struct *child, long request,
         unsigned long addr, unsigned long data)
{
    int i, ret;
    unsigned long __user *p = (void __user *)data;
    void __user *vp = p;

    switch (request) {
    /* read the word at location addr in the USER area. */
    case PTRACE_PEEKUSR:
        ret = peek_user(child, addr, data);
        break;

    /* write the word at location addr in the USER area */
    case PTRACE_POKEUSR:
        ret = poke_user(child, addr, data);
        break;

    case PTRACE_SYSEMU:
    case PTRACE_SYSEMU_SINGLESTEP:
        ret = -EIO;
        break;

#ifdef PTRACE_GETREGS
    case PTRACE_GETREGS: { /* Get all gp regs from the child. */
        if (!access_ok(VERIFY_WRITE, p, MAX_REG_OFFSET)) {
            ret = -EIO;
            break;
        }
        for ( i = 0; i < MAX_REG_OFFSET; i += sizeof(long) ) {
            __put_user(getreg(child, i), p);
            p++;
        }
        ret = 0;
        break;
    }
#endif
#ifdef PTRACE_SETREGS
    case PTRACE_SETREGS: { /* Set all gp regs in the child. */
        unsigned long tmp = 0;
        if (!access_ok(VERIFY_READ, p, MAX_REG_OFFSET)) {
            ret = -EIO;
            break;
        }
        for ( i = 0; i < MAX_REG_OFFSET; i += sizeof(long) ) {
            __get_user(tmp, p);
            putreg(child, i, tmp);
            p++;
        }
        ret = 0;
        break;
    }
#endif
    case PTRACE_GET_THREAD_AREA:
        ret = ptrace_get_thread_area(child, addr, vp);
        break;

    case PTRACE_SET_THREAD_AREA:
        ret = ptrace_set_thread_area(child, addr, vp);
        break;

    case PTRACE_FAULTINFO: {
        /*
         * Take the info from thread->arch->faultinfo,
         * but transfer max. sizeof(struct ptrace_faultinfo).
         * On i386, ptrace_faultinfo is smaller!
         */
        ret = copy_to_user(p, &child->thread.arch.faultinfo,
                   sizeof(struct ptrace_faultinfo)) ?
            -EIO : 0;
        break;
    }

#ifdef PTRACE_LDT
    case PTRACE_LDT: {
        struct ptrace_ldt ldt;

        if (copy_from_user(&ldt, p, sizeof(ldt))) {
            ret = -EIO;
            break;
        }

        /*
         * This one is confusing, so just punt and return -EIO for
         * now
         */
        ret = -EIO;
        break;
    }
#endif
    default:
        ret = ptrace_request(child, request, addr, data);
        if (ret == -EIO)
            ret = subarch_ptrace(child, request, addr, data);
        break;
    }

    return ret;
}

static void send_sigtrap(struct task_struct *tsk, struct uml_pt_regs *regs,
          int error_code)
{
    struct siginfo info;

    memset(&info, 0, sizeof(info));
    info.si_signo = SIGTRAP;
    info.si_code = TRAP_BRKPT;

    /* User-mode eip? */
    info.si_addr = UPT_IS_USER(regs) ? (void __user *) UPT_IP(regs) : NULL;

    /* Send us the fake SIGTRAP */
    force_sig_info(SIGTRAP, &info, tsk);
}

/*
 * XXX Check PT_DTRACE vs TIF_SINGLESTEP for singlestepping check and
 * PT_PTRACED vs TIF_SYSCALL_TRACE for syscall tracing check
 */
void syscall_trace_enter(struct pt_regs *regs)
{
    audit_syscall_entry(HOST_AUDIT_ARCH,
                UPT_SYSCALL_NR(&regs->regs),
                UPT_SYSCALL_ARG1(&regs->regs),
                UPT_SYSCALL_ARG2(&regs->regs),
                UPT_SYSCALL_ARG3(&regs->regs),
                UPT_SYSCALL_ARG4(&regs->regs));

    if (!test_thread_flag(TIF_SYSCALL_TRACE))
        return;

    tracehook_report_syscall_entry(regs);
}

void syscall_trace_leave(struct pt_regs *regs)
{
    int ptraced = current->ptrace;

    audit_syscall_exit(regs);

    /* Fake a debug trap */
    if (ptraced & PT_DTRACE)
        send_sigtrap(current, &regs->regs, 0);

    if (!test_thread_flag(TIF_SYSCALL_TRACE))
        return;

    tracehook_report_syscall_exit(regs, 0);
    /* force do_signal() --> is_syscall() */
    if (ptraced & PT_PTRACED)
        set_thread_flag(TIF_SIGPENDING);
}