#include <linux/audit.h>
#include <linux/pid_namespace.h>
#include <linux/syscalls.h>
+#include <linux/uaccess.h>
-#include <asm/pgtable.h>
-#include <asm/uaccess.h>
/*
* ptrace a task: make the debugger its new parent and
*/
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);
+ BUG_ON(!list_empty(&child->ptrace_entry));
+ list_add(&child->ptrace_entry, &new_parent->ptraced);
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
* TASK_TRACED, resume it now.
* Requires that irqs be disabled.
*/
-void ptrace_untrace(struct task_struct *child)
+static void ptrace_untrace(struct task_struct *child)
{
spin_lock(&child->sighand->siglock);
if (task_is_traced(child)) {
- if (child->signal->flags & SIGNAL_STOP_STOPPED) {
+ /*
+ * If the group stop is completed or in progress,
+ * this thread was already counted as stopped.
+ */
+ if (child->signal->flags & SIGNAL_STOP_STOPPED ||
+ child->signal->group_stop_count)
__set_task_state(child, TASK_STOPPED);
- } else {
+ else
signal_wake_up(child, 1);
- }
}
spin_unlock(&child->sighand->siglock);
}
BUG_ON(!child->ptrace);
child->ptrace = 0;
- if (ptrace_reparented(child)) {
- list_del_init(&child->ptrace_list);
- remove_parent(child);
- child->parent = child->real_parent;
- add_parent(child);
- }
+ child->parent = child->real_parent;
+ list_del_init(&child->ptrace_entry);
+ arch_ptrace_untrace(child);
if (task_is_traced(child))
ptrace_untrace(child);
}
read_unlock(&tasklist_lock);
if (!ret && !kill)
- wait_task_inactive(child);
+ ret = wait_task_inactive(child, TASK_TRACED) ? 0 : -ESRCH;
/* All systems go.. */
return ret;
}
-int __ptrace_may_attach(struct task_struct *task)
+int __ptrace_may_access(struct task_struct *task, unsigned int mode)
{
+ const struct cred *cred = current_cred(), *tcred;
+
/* May we inspect the given task?
* This check is used both for attaching with ptrace
* and for allowing access to sensitive information in /proc.
/* 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))
+ rcu_read_lock();
+ tcred = __task_cred(task);
+ if ((cred->uid != tcred->euid ||
+ cred->uid != tcred->suid ||
+ cred->uid != tcred->uid ||
+ cred->gid != tcred->egid ||
+ cred->gid != tcred->sgid ||
+ cred->gid != tcred->gid) &&
+ !capable(CAP_SYS_PTRACE)) {
+ rcu_read_unlock();
return -EPERM;
+ }
+ rcu_read_unlock();
smp_rmb();
if (task->mm)
dumpable = get_dumpable(task->mm);
if (!dumpable && !capable(CAP_SYS_PTRACE))
return -EPERM;
- return security_ptrace(current, task);
+ return security_ptrace_access_check(task, mode);
}
-int ptrace_may_attach(struct task_struct *task)
+bool ptrace_may_access(struct task_struct *task, unsigned int mode)
{
int err;
task_lock(task);
- err = __ptrace_may_attach(task);
+ err = __ptrace_may_access(task, mode);
task_unlock(task);
return !err;
}
int ptrace_attach(struct task_struct *task)
{
int retval;
- unsigned long flags;
audit_ptrace(task);
retval = -EPERM;
+ if (unlikely(task->flags & PF_KTHREAD))
+ goto out;
if (same_thread_group(task, current))
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).
+ * Protect exec's credential calculations against our interference;
+ * interference; SUID, SGID and LSM creds get determined differently
+ * under ptrace.
*/
- task_lock(task);
- if (!write_trylock_irqsave(&tasklist_lock, flags)) {
- task_unlock(task);
- do {
- cpu_relax();
- } while (!write_can_lock(&tasklist_lock));
- goto repeat;
- }
+ retval = -ERESTARTNOINTR;
+ if (mutex_lock_interruptible(&task->cred_guard_mutex))
+ goto out;
- if (!task->mm)
- goto bad;
- /* the same process cannot be attached many times */
- if (task->ptrace & PT_PTRACED)
- goto bad;
- retval = __ptrace_may_attach(task);
+ task_lock(task);
+ retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
+ task_unlock(task);
if (retval)
- goto bad;
+ goto unlock_creds;
+
+ write_lock_irq(&tasklist_lock);
+ retval = -EPERM;
+ if (unlikely(task->exit_state))
+ goto unlock_tasklist;
+ if (task->ptrace)
+ goto unlock_tasklist;
- /* Go */
- task->ptrace |= PT_PTRACED;
+ task->ptrace = PT_PTRACED;
if (capable(CAP_SYS_PTRACE))
task->ptrace |= PT_PTRACE_CAP;
__ptrace_link(task, current);
-
send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
-bad:
- write_unlock_irqrestore(&tasklist_lock, flags);
- task_unlock(task);
+
+ retval = 0;
+unlock_tasklist:
+ write_unlock_irq(&tasklist_lock);
+unlock_creds:
+ mutex_unlock(&task->cred_guard_mutex);
out:
return retval;
}
-static inline void __ptrace_detach(struct task_struct *child, unsigned int data)
+/**
+ * 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;
+
+ write_lock_irq(&tasklist_lock);
+ /* Are we already being traced? */
+ if (!current->ptrace) {
+ ret = security_ptrace_traceme(current->parent);
+ /*
+ * Check PF_EXITING to ensure ->real_parent has not passed
+ * exit_ptrace(). Otherwise we don't report the error but
+ * pretend ->real_parent untraces us right after return.
+ */
+ if (!ret && !(current->real_parent->flags & PF_EXITING)) {
+ current->ptrace = PT_PTRACED;
+ __ptrace_link(current, current->real_parent);
+ }
+ }
+ write_unlock_irq(&tasklist_lock);
+
+ return ret;
+}
+
+/*
+ * Called with irqs disabled, returns true if childs should reap themselves.
+ */
+static int ignoring_children(struct sighand_struct *sigh)
{
- child->exit_code = data;
- /* .. re-parent .. */
- __ptrace_unlink(child);
- /* .. and wake it up. */
- if (child->exit_state != EXIT_ZOMBIE)
- wake_up_process(child);
+ int ret;
+ spin_lock(&sigh->siglock);
+ ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
+ (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
+ spin_unlock(&sigh->siglock);
+ return ret;
+}
+
+/*
+ * Called with tasklist_lock held for writing.
+ * Unlink a traced task, and clean it up if it was a traced zombie.
+ * Return true if it needs to be reaped with release_task().
+ * (We can't call release_task() here because we already hold tasklist_lock.)
+ *
+ * If it's a zombie, our attachedness prevented normal parent notification
+ * or self-reaping. Do notification now if it would have happened earlier.
+ * If it should reap itself, return true.
+ *
+ * If it's our own child, there is no notification to do. But if our normal
+ * children self-reap, then this child was prevented by ptrace and we must
+ * reap it now, in that case we must also wake up sub-threads sleeping in
+ * do_wait().
+ */
+static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
+{
+ __ptrace_unlink(p);
+
+ if (p->exit_state == EXIT_ZOMBIE) {
+ if (!task_detached(p) && thread_group_empty(p)) {
+ if (!same_thread_group(p->real_parent, tracer))
+ do_notify_parent(p, p->exit_signal);
+ else if (ignoring_children(tracer->sighand)) {
+ __wake_up_parent(p, tracer);
+ p->exit_signal = -1;
+ }
+ }
+ if (task_detached(p)) {
+ /* Mark it as in the process of being reaped. */
+ p->exit_state = EXIT_DEAD;
+ return true;
+ }
+ }
+
+ return false;
}
int ptrace_detach(struct task_struct *child, unsigned int data)
{
+ bool dead = false;
+
if (!valid_signal(data))
return -EIO;
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
write_lock_irq(&tasklist_lock);
- /* protect against de_thread()->release_task() */
- if (child->ptrace)
- __ptrace_detach(child, data);
+ /*
+ * This child can be already killed. Make sure de_thread() or
+ * our sub-thread doing do_wait() didn't do release_task() yet.
+ */
+ if (child->ptrace) {
+ child->exit_code = data;
+ dead = __ptrace_detach(current, child);
+ if (!child->exit_state)
+ wake_up_process(child);
+ }
write_unlock_irq(&tasklist_lock);
+ if (unlikely(dead))
+ release_task(child);
+
return 0;
}
+/*
+ * Detach all tasks we were using ptrace on.
+ */
+void exit_ptrace(struct task_struct *tracer)
+{
+ struct task_struct *p, *n;
+ LIST_HEAD(ptrace_dead);
+
+ write_lock_irq(&tasklist_lock);
+ list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
+ if (__ptrace_detach(tracer, p))
+ list_add(&p->ptrace_entry, &ptrace_dead);
+ }
+ write_unlock_irq(&tasklist_lock);
+
+ BUG_ON(!list_empty(&tracer->ptraced));
+
+ list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
+ list_del_init(&p->ptrace_entry);
+ release_task(p);
+ }
+}
+
int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
{
int copied = 0;
copied += retval;
src += retval;
dst += retval;
- len -= retval;
+ len -= retval;
}
return copied;
}
copied += retval;
src += retval;
dst += retval;
- len -= retval;
+ len -= retval;
}
return copied;
}
static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
{
+ unsigned long flags;
int error = -ESRCH;
- read_lock(&tasklist_lock);
- if (likely(child->sighand != NULL)) {
+ if (lock_task_sighand(child, &flags)) {
error = -EINVAL;
- spin_lock_irq(&child->sighand->siglock);
if (likely(child->last_siginfo != NULL)) {
*info = *child->last_siginfo;
error = 0;
}
- spin_unlock_irq(&child->sighand->siglock);
+ unlock_task_sighand(child, &flags);
}
- read_unlock(&tasklist_lock);
return error;
}
static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
{
+ unsigned long flags;
int error = -ESRCH;
- read_lock(&tasklist_lock);
- if (likely(child->sighand != NULL)) {
+ if (lock_task_sighand(child, &flags)) {
error = -EINVAL;
- spin_lock_irq(&child->sighand->siglock);
if (likely(child->last_siginfo != NULL)) {
*child->last_siginfo = *info;
error = 0;
}
- spin_unlock_irq(&child->sighand->siglock);
+ unlock_task_sighand(child, &flags);
}
- read_unlock(&tasklist_lock);
return error;
}
if (unlikely(!arch_has_single_step()))
return -EIO;
user_enable_single_step(child);
- }
- else
+ } else {
user_disable_single_step(child);
+ }
child->exit_code = data;
wake_up_process(child);
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)
+static struct task_struct *ptrace_get_task_struct(pid_t pid)
{
struct task_struct *child;
- read_lock(&tasklist_lock);
+ rcu_read_lock();
child = find_task_by_vpid(pid);
if (child)
get_task_struct(child);
+ rcu_read_unlock();
- read_unlock(&tasklist_lock);
if (!child)
return ERR_PTR(-ESRCH);
return child;
#define arch_ptrace_attach(child) do { } while (0)
#endif
-asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
+SYSCALL_DEFINE4(ptrace, long, request, long, pid, long, addr, long, data)
{
struct task_struct *child;
long ret;
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);
return (copied == sizeof(data)) ? 0 : -EIO;
}
-#if defined CONFIG_COMPAT && defined __ARCH_WANT_COMPAT_SYS_PTRACE
+#if defined CONFIG_COMPAT
#include <linux/compat.h>
int compat_ptrace_request(struct task_struct *child, compat_long_t request,
unlock_kernel();
return ret;
}
-#endif /* CONFIG_COMPAT && __ARCH_WANT_COMPAT_SYS_PTRACE */
+#endif /* CONFIG_COMPAT */
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff