/* * linux/kernel/ptrace.c * * (C) Copyright 1999 Linus Torvalds * * Common interfaces for "ptrace()" which we do not want * to continually duplicate across every architecture. */ #include <linux/capability.h>#include <linux/module.h>#include <linux/sched.h>#include <linux/errno.h>#include <linux/mm.h>#include <linux/highmem.h>#include <linux/pagemap.h>#include <linux/smp_lock.h>#include <linux/ptrace.h>#include <linux/security.h>#include <linux/signal.h> #include <asm/pgtable.h>#include <asm/uaccess.h> /* * ptrace a task: make the debugger its new parent and * move it to the ptrace list. * * Must be called with the tasklist lock write-held. */void __ptrace_link(struct task_struct *child, struct task_struct *new_parent){ BUG_ON(!list_empty(&child->ptrace_list)); if (child->parent == new_parent) return; list_add(&child->ptrace_list, &child->parent->ptrace_children); remove_parent(child); child->parent = new_parent; add_parent(child);} /* * Turn a tracing stop into a normal stop now, since with no tracer there * would be no way to wake it up with SIGCONT or SIGKILL. If there was a * signal sent that would resume the child, but didn't because it was in * TASK_TRACED, resume it now. * Requires that irqs be disabled. */void ptrace_untrace(struct task_struct *child){ spin_lock(&child->sighand->siglock); if (child->state == TASK_TRACED) { if (child->signal->flags & SIGNAL_STOP_STOPPED) { child->state = TASK_STOPPED; } else { signal_wake_up(child, 1); } } spin_unlock(&child->sighand->siglock);} /* * unptrace a task: move it back to its original parent and * remove it from the ptrace list. * * Must be called with the tasklist lock write-held. */void __ptrace_unlink(struct task_struct *child){ BUG_ON(!child->ptrace); child->ptrace = 0; if (!list_empty(&child->ptrace_list)) { list_del_init(&child->ptrace_list); remove_parent(child); child->parent = child->real_parent; add_parent(child); } if (child->state == TASK_TRACED) ptrace_untrace(child);} /* * Check that we have indeed attached to the thing.. */int ptrace_check_attach(struct task_struct *child, int kill){ int ret = -ESRCH; /* * We take the read lock around doing both checks to close a * possible race where someone else was tracing our child and * detached between these two checks. After this locked check, * we are sure that this is our traced child and that can only * be changed by us so it's not changing right after this. */ read_lock(&tasklist_lock); if ((child->ptrace & PT_PTRACED) && child->parent == current && (!(child->ptrace & PT_ATTACHED) || child->real_parent != current) && child->signal != NULL) { ret = 0; spin_lock_irq(&child->sighand->siglock); if (child->state == TASK_STOPPED) { child->state = TASK_TRACED; } else if (child->state != TASK_TRACED && !kill) { ret = -ESRCH; } spin_unlock_irq(&child->sighand->siglock); } read_unlock(&tasklist_lock); if (!ret && !kill) { wait_task_inactive(child); } /* All systems go.. */ return ret;} static int may_attach(struct task_struct *task){ /* May we inspect the given task? * This check is used both for attaching with ptrace * and for allowing access to sensitive information in /proc. * * ptrace_attach denies several cases that /proc allows * because setting up the necessary parent/child relationship * or halting the specified task is impossible. */ int dumpable = 0; /* Don't let security modules deny introspection */ if (task == current) return 0; if (((current->uid != task->euid) || (current->uid != task->suid) || (current->uid != task->uid) || (current->gid != task->egid) || (current->gid != task->sgid) || (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE)) return -EPERM; smp_rmb(); if (task->mm) dumpable = task->mm->dumpable; if (!dumpable && !capable(CAP_SYS_PTRACE)) return -EPERM; return security_ptrace(current, task);} int ptrace_may_attach(struct task_struct *task){ int err; task_lock(task); err = may_attach(task); task_unlock(task); return !err;} int ptrace_attach(struct task_struct *task){ int retval; retval = -EPERM; if (task->pid <= 1) goto out; if (task->tgid == current->tgid) goto out; repeat: /* * Nasty, nasty. * * We want to hold both the task-lock and the * tasklist_lock for writing at the same time. * But that's against the rules (tasklist_lock * is taken for reading by interrupts on other * cpu's that may have task_lock). */ task_lock(task); local_irq_disable(); if (!write_trylock(&tasklist_lock)) { local_irq_enable(); task_unlock(task); do { cpu_relax(); } while (!write_can_lock(&tasklist_lock)); goto repeat; } if (!task->mm) goto bad; /* the same process cannot be attached many times */ if (task->ptrace & PT_PTRACED) goto bad; retval = may_attach(task); if (retval) goto bad; /* Go */ task->ptrace |= PT_PTRACED | ((task->real_parent != current) ? PT_ATTACHED : 0); if (capable(CAP_SYS_PTRACE)) task->ptrace |= PT_PTRACE_CAP; __ptrace_link(task, current); force_sig_specific(SIGSTOP, task); bad: write_unlock_irq(&tasklist_lock); task_unlock(task);out: return retval;} static inline void __ptrace_detach(struct task_struct *child, unsigned int data){ child->exit_code = data; /* .. re-parent .. */ __ptrace_unlink(child); /* .. and wake it up. */ if (child->exit_state != EXIT_ZOMBIE) wake_up_process(child);} int ptrace_detach(struct task_struct *child, unsigned int data){ if (!valid_signal(data)) return -EIO; /* Architecture-specific hardware disable .. */ ptrace_disable(child); write_lock_irq(&tasklist_lock); /* protect against de_thread()->release_task() */ if (child->ptrace) __ptrace_detach(child, data); write_unlock_irq(&tasklist_lock); return 0;} int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len){ int copied = 0; while (len > 0) { char buf[128]; int this_len, retval; this_len = (len > sizeof(buf)) ? sizeof(buf) : len; retval = access_process_vm(tsk, src, buf, this_len, 0); if (!retval) { if (copied) break; return -EIO; } if (copy_to_user(dst, buf, retval)) return -EFAULT; copied += retval; src += retval; dst += retval; len -= retval; } return copied;} int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len){ int copied = 0; while (len > 0) { char buf[128]; int this_len, retval; this_len = (len > sizeof(buf)) ? sizeof(buf) : len; if (copy_from_user(buf, src, this_len)) return -EFAULT; retval = access_process_vm(tsk, dst, buf, this_len, 1); if (!retval) { if (copied) break; return -EIO; } copied += retval; src += retval; dst += retval; len -= retval; } return copied;} static int ptrace_setoptions(struct task_struct *child, long data){ child->ptrace &= ~PT_TRACE_MASK; if (data & PTRACE_O_TRACESYSGOOD) child->ptrace |= PT_TRACESYSGOOD; if (data & PTRACE_O_TRACEFORK) child->ptrace |= PT_TRACE_FORK; if (data & PTRACE_O_TRACEVFORK) child->ptrace |= PT_TRACE_VFORK; if (data & PTRACE_O_TRACECLONE) child->ptrace |= PT_TRACE_CLONE; if (data & PTRACE_O_TRACEEXEC) child->ptrace |= PT_TRACE_EXEC; if (data & PTRACE_O_TRACEVFORKDONE) child->ptrace |= PT_TRACE_VFORK_DONE; if (data & PTRACE_O_TRACEEXIT) child->ptrace |= PT_TRACE_EXIT; return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;} static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data){ siginfo_t lastinfo; int error = -ESRCH; read_lock(&tasklist_lock); if (likely(child->sighand != NULL)) { error = -EINVAL; spin_lock_irq(&child->sighand->siglock); if (likely(child->last_siginfo != NULL)) { lastinfo = *child->last_siginfo; error = 0; } spin_unlock_irq(&child->sighand->siglock); } read_unlock(&tasklist_lock); if (!error) return copy_siginfo_to_user(data, &lastinfo); return error;} static int ptrace_setsiginfo(struct task_struct *child, siginfo_t __user * data){ siginfo_t newinfo; int error = -ESRCH; if (copy_from_user(&newinfo, data, sizeof (siginfo_t))) return -EFAULT; read_lock(&tasklist_lock); if (likely(child->sighand != NULL)) { error = -EINVAL; spin_lock_irq(&child->sighand->siglock); if (likely(child->last_siginfo != NULL)) { *child->last_siginfo = newinfo; error = 0; } spin_unlock_irq(&child->sighand->siglock); } read_unlock(&tasklist_lock); return error;} int ptrace_request(struct task_struct *child, long request, long addr, long data){ int ret = -EIO; switch (request) {#ifdef PTRACE_OLDSETOPTIONS case PTRACE_OLDSETOPTIONS:#endif case PTRACE_SETOPTIONS: ret = ptrace_setoptions(child, data); break; case PTRACE_GETEVENTMSG: ret = put_user(child->ptrace_message, (unsigned long __user *) data); break; case PTRACE_GETSIGINFO: ret = ptrace_getsiginfo(child, (siginfo_t __user *) data); break; case PTRACE_SETSIGINFO: ret = ptrace_setsiginfo(child, (siginfo_t __user *) data); break; default: break; } return ret;} /** * ptrace_traceme -- helper for PTRACE_TRACEME * * Performs checks and sets PT_PTRACED. * Should be used by all ptrace implementations for PTRACE_TRACEME. */int ptrace_traceme(void){ int ret = -EPERM; /* * Are we already being traced? */ task_lock(current); if (!(current->ptrace & PT_PTRACED)) { ret = security_ptrace(current->parent, current); /* * Set the ptrace bit in the process ptrace flags. */ if (!ret) current->ptrace |= PT_PTRACED; } task_unlock(current); return ret;} /** * ptrace_get_task_struct -- grab a task struct reference for ptrace * @pid: process id to grab a task_struct reference of * * This function is a helper for ptrace implementations. It checks * permissions and then grabs a task struct for use of the actual * ptrace implementation. * * Returns the task_struct for @pid or an ERR_PTR() on failure. */struct task_struct *ptrace_get_task_struct(pid_t pid){ struct task_struct *child; /* * Tracing init is not allowed. */ if (pid == 1) return ERR_PTR(-EPERM); read_lock(&tasklist_lock); child = find_task_by_pid(pid); if (child) get_task_struct(child); read_unlock(&tasklist_lock); if (!child) return ERR_PTR(-ESRCH); return child;} #ifndef __ARCH_SYS_PTRACEasmlinkage long sys_ptrace(long request, long pid, long addr, long data){ struct task_struct *child; long ret; /* * This lock_kernel fixes a subtle race with suid exec */ lock_kernel(); if (request == PTRACE_TRACEME) { ret = ptrace_traceme(); goto out; } child = ptrace_get_task_struct(pid); if (IS_ERR(child)) { ret = PTR_ERR(child); goto out; } if (request == PTRACE_ATTACH) { ret = ptrace_attach(child); goto out_put_task_struct; } ret = ptrace_check_attach(child, request == PTRACE_KILL); if (ret < 0) goto out_put_task_struct; ret = arch_ptrace(child, request, addr, data); if (ret < 0) goto out_put_task_struct; out_put_task_struct: put_task_struct(child); out: unlock_kernel(); return ret;}#endif /* __ARCH_SYS_PTRACE */
/*
* linux/kernel/ptrace.c
*
* (C) Copyright 1999 Linus Torvalds
*
* Common interfaces for "ptrace()" which we do not want
* to continually duplicate across every architecture.
*/
#include <linux/capability.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/smp_lock.h>
#include <linux/ptrace.h>
#include <linux/security.h>
#include <linux/signal.h>
#include <asm/pgtable.h>
#include <asm/uaccess.h>
/*
* ptrace a task: make the debugger its new parent and
* move it to the ptrace list.
*
* Must be called with the tasklist lock write-held.
*/
void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
{
BUG_ON(!list_empty(&child->ptrace_list));
if (child->parent == new_parent)
return;
list_add(&child->ptrace_list, &child->parent->ptrace_children);
remove_parent(child);
child->parent = new_parent;
add_parent(child);
}
/*
* Turn a tracing stop into a normal stop now, since with no tracer there
* would be no way to wake it up with SIGCONT or SIGKILL. If there was a
* signal sent that would resume the child, but didn't because it was in
* TASK_TRACED, resume it now.
* Requires that irqs be disabled.
*/
void ptrace_untrace(struct task_struct *child)
{
spin_lock(&child->sighand->siglock);
if (child->state == TASK_TRACED) {
if (child->signal->flags & SIGNAL_STOP_STOPPED) {
child->state = TASK_STOPPED;
} else {
signal_wake_up(child, 1);
}
}
spin_unlock(&child->sighand->siglock);
}
/*
* unptrace a task: move it back to its original parent and
* remove it from the ptrace list.
*
* Must be called with the tasklist lock write-held.
*/
void __ptrace_unlink(struct task_struct *child)
{
BUG_ON(!child->ptrace);
child->ptrace = 0;
if (!list_empty(&child->ptrace_list)) {
list_del_init(&child->ptrace_list);
remove_parent(child);
child->parent = child->real_parent;
add_parent(child);
}
if (child->state == TASK_TRACED)
ptrace_untrace(child);
}
/*
* Check that we have indeed attached to the thing..
*/
int ptrace_check_attach(struct task_struct *child, int kill)
{
int ret = -ESRCH;
/*
* We take the read lock around doing both checks to close a
* possible race where someone else was tracing our child and
* detached between these two checks. After this locked check,
* we are sure that this is our traced child and that can only
* be changed by us so it's not changing right after this.
*/
read_lock(&tasklist_lock);
if ((child->ptrace & PT_PTRACED) && child->parent == current &&
(!(child->ptrace & PT_ATTACHED) || child->real_parent != current)
&& child->signal != NULL) {
ret = 0;
spin_lock_irq(&child->sighand->siglock);
if (child->state == TASK_STOPPED) {
child->state = TASK_TRACED;
} else if (child->state != TASK_TRACED && !kill) {
ret = -ESRCH;
}
spin_unlock_irq(&child->sighand->siglock);
}
read_unlock(&tasklist_lock);
if (!ret && !kill) {
wait_task_inactive(child);
}
/* All systems go.. */
return ret;
}
static int may_attach(struct task_struct *task)
{
/* May we inspect the given task?
* This check is used both for attaching with ptrace
* and for allowing access to sensitive information in /proc.
*
* ptrace_attach denies several cases that /proc allows
* because setting up the necessary parent/child relationship
* or halting the specified task is impossible.
*/
int dumpable = 0;
/* Don't let security modules deny introspection */
if (task == current)
return 0;
if (((current->uid != task->euid) ||
(current->uid != task->suid) ||
(current->uid != task->uid) ||
(current->gid != task->egid) ||
(current->gid != task->sgid) ||
(current->gid != task->gid)) && !capable(CAP_SYS_PTRACE))
return -EPERM;
smp_rmb();
if (task->mm)
dumpable = task->mm->dumpable;
if (!dumpable && !capable(CAP_SYS_PTRACE))
return -EPERM;
return security_ptrace(current, task);
}
int ptrace_may_attach(struct task_struct *task)
{
int err;
task_lock(task);
err = may_attach(task);
task_unlock(task);
return !err;
}
int ptrace_attach(struct task_struct *task)
{
int retval;
retval = -EPERM;
if (task->pid <= 1)
goto out;
if (task->tgid == current->tgid)
goto out;
repeat:
/*
* Nasty, nasty.
*
* We want to hold both the task-lock and the
* tasklist_lock for writing at the same time.
* But that's against the rules (tasklist_lock
* is taken for reading by interrupts on other
* cpu's that may have task_lock).
*/
task_lock(task);
local_irq_disable();
if (!write_trylock(&tasklist_lock)) {
local_irq_enable();
task_unlock(task);
do {
cpu_relax();
} while (!write_can_lock(&tasklist_lock));
goto repeat;
}
if (!task->mm)
goto bad;
/* the same process cannot be attached many times */
if (task->ptrace & PT_PTRACED)
goto bad;
retval = may_attach(task);
if (retval)
goto bad;
/* Go */
task->ptrace |= PT_PTRACED | ((task->real_parent != current)
? PT_ATTACHED : 0);
if (capable(CAP_SYS_PTRACE))
task->ptrace |= PT_PTRACE_CAP;
__ptrace_link(task, current);
force_sig_specific(SIGSTOP, task);
bad:
write_unlock_irq(&tasklist_lock);
task_unlock(task);
out:
return retval;
}
static inline void __ptrace_detach(struct task_struct *child, unsigned int data)
{
child->exit_code = data;
/* .. re-parent .. */
__ptrace_unlink(child);
/* .. and wake it up. */
if (child->exit_state != EXIT_ZOMBIE)
wake_up_process(child);
}
int ptrace_detach(struct task_struct *child, unsigned int data)
{
if (!valid_signal(data))
return -EIO;
/* Architecture-specific hardware disable .. */
ptrace_disable(child);
write_lock_irq(&tasklist_lock);
/* protect against de_thread()->release_task() */
if (child->ptrace)
__ptrace_detach(child, data);
write_unlock_irq(&tasklist_lock);
return 0;
}
int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
{
int copied = 0;
while (len > 0) {
char buf[128];
int this_len, retval;
this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
retval = access_process_vm(tsk, src, buf, this_len, 0);
if (!retval) {
if (copied)
break;
return -EIO;
}
if (copy_to_user(dst, buf, retval))
return -EFAULT;
copied += retval;
src += retval;
dst += retval;
len -= retval;
}
return copied;
}
int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
{
int copied = 0;
while (len > 0) {
char buf[128];
int this_len, retval;
this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
if (copy_from_user(buf, src, this_len))
return -EFAULT;
retval = access_process_vm(tsk, dst, buf, this_len, 1);
if (!retval) {
if (copied)
break;
return -EIO;
}
copied += retval;
src += retval;
dst += retval;
len -= retval;
}
return copied;
}
static int ptrace_setoptions(struct task_struct *child, long data)
{
child->ptrace &= ~PT_TRACE_MASK;
if (data & PTRACE_O_TRACESYSGOOD)
child->ptrace |= PT_TRACESYSGOOD;
if (data & PTRACE_O_TRACEFORK)
child->ptrace |= PT_TRACE_FORK;
if (data & PTRACE_O_TRACEVFORK)
child->ptrace |= PT_TRACE_VFORK;
if (data & PTRACE_O_TRACECLONE)
child->ptrace |= PT_TRACE_CLONE;
if (data & PTRACE_O_TRACEEXEC)
child->ptrace |= PT_TRACE_EXEC;
if (data & PTRACE_O_TRACEVFORKDONE)
child->ptrace |= PT_TRACE_VFORK_DONE;
if (data & PTRACE_O_TRACEEXIT)
child->ptrace |= PT_TRACE_EXIT;
return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
}
static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data)
{
siginfo_t lastinfo;
int error = -ESRCH;
read_lock(&tasklist_lock);
if (likely(child->sighand != NULL)) {
error = -EINVAL;
spin_lock_irq(&child->sighand->siglock);
if (likely(child->last_siginfo != NULL)) {
lastinfo = *child->last_siginfo;
error = 0;
}
spin_unlock_irq(&child->sighand->siglock);
}
read_unlock(&tasklist_lock);
if (!error)
return copy_siginfo_to_user(data, &lastinfo);
return error;
}
static int ptrace_setsiginfo(struct task_struct *child, siginfo_t __user * data)
{
siginfo_t newinfo;
int error = -ESRCH;
if (copy_from_user(&newinfo, data, sizeof (siginfo_t)))
return -EFAULT;
read_lock(&tasklist_lock);
if (likely(child->sighand != NULL)) {
error = -EINVAL;
spin_lock_irq(&child->sighand->siglock);
if (likely(child->last_siginfo != NULL)) {
*child->last_siginfo = newinfo;
error = 0;
}
spin_unlock_irq(&child->sighand->siglock);
}
read_unlock(&tasklist_lock);
return error;
}
int ptrace_request(struct task_struct *child, long request,
long addr, long data)
{
int ret = -EIO;
switch (request) {
#ifdef PTRACE_OLDSETOPTIONS
case PTRACE_OLDSETOPTIONS:
#endif
case PTRACE_SETOPTIONS:
ret = ptrace_setoptions(child, data);
break;
case PTRACE_GETEVENTMSG:
ret = put_user(child->ptrace_message, (unsigned long __user *) data);
break;
case PTRACE_GETSIGINFO:
ret = ptrace_getsiginfo(child, (siginfo_t __user *) data);
break;
case PTRACE_SETSIGINFO:
ret = ptrace_setsiginfo(child, (siginfo_t __user *) data);
break;
default:
break;
}
return ret;
}
/**
* ptrace_traceme -- helper for PTRACE_TRACEME
*
* Performs checks and sets PT_PTRACED.
* Should be used by all ptrace implementations for PTRACE_TRACEME.
*/
int ptrace_traceme(void)
{
int ret = -EPERM;
/*
* Are we already being traced?
*/
task_lock(current);
if (!(current->ptrace & PT_PTRACED)) {
ret = security_ptrace(current->parent, current);
/*
* Set the ptrace bit in the process ptrace flags.
*/
if (!ret)
current->ptrace |= PT_PTRACED;
}
task_unlock(current);
return ret;
}
/**
* ptrace_get_task_struct -- grab a task struct reference for ptrace
* @pid: process id to grab a task_struct reference of
*
* This function is a helper for ptrace implementations. It checks
* permissions and then grabs a task struct for use of the actual
* ptrace implementation.
*
* Returns the task_struct for @pid or an ERR_PTR() on failure.
*/
struct task_struct *ptrace_get_task_struct(pid_t pid)
{
struct task_struct *child;
/*
* Tracing init is not allowed.
*/
if (pid == 1)
return ERR_PTR(-EPERM);
read_lock(&tasklist_lock);
child = find_task_by_pid(pid);
if (child)
get_task_struct(child);
read_unlock(&tasklist_lock);
if (!child)
return ERR_PTR(-ESRCH);
return child;
}
#ifndef __ARCH_SYS_PTRACE
asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
{
struct task_struct *child;
long ret;
/*
* This lock_kernel fixes a subtle race with suid exec
*/
lock_kernel();
if (request == PTRACE_TRACEME) {
ret = ptrace_traceme();
goto out;
}
child = ptrace_get_task_struct(pid);
if (IS_ERR(child)) {
ret = PTR_ERR(child);
goto out;
}
if (request == PTRACE_ATTACH) {
ret = ptrace_attach(child);
goto out_put_task_struct;
}
ret = ptrace_check_attach(child, request == PTRACE_KILL);
if (ret < 0)
goto out_put_task_struct;
ret = arch_ptrace(child, request, addr, data);
if (ret < 0)
goto out_put_task_struct;
out_put_task_struct:
put_task_struct(child);
out:
unlock_kernel();
return ret;
}
#endif /* __ARCH_SYS_PTRACE */