* to continually duplicate across every architecture.
*/
+#include <linux/capability.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/smp_lock.h>
#include <linux/ptrace.h>
#include <linux/security.h>
+#include <linux/signal.h>
+#include <linux/vs_base.h>
#include <asm/pgtable.h>
#include <asm/uaccess.h>
*
* Must be called with the tasklist lock write-held.
*/
-void __ptrace_link(task_t *child, task_t *new_parent)
+void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
{
- if (!list_empty(&child->ptrace_list))
- BUG();
+ BUG_ON(!list_empty(&child->ptrace_list));
if (child->parent == new_parent)
return;
list_add(&child->ptrace_list, &child->parent->ptrace_children);
- REMOVE_LINKS(child);
+ remove_parent(child);
child->parent = new_parent;
- SET_LINKS(child);
+ 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(task_t *child)
+void __ptrace_unlink(struct task_struct *child)
{
- if (!child->ptrace)
- BUG();
+ BUG_ON(!child->ptrace);
+
child->ptrace = 0;
- if (list_empty(&child->ptrace_list))
- return;
- list_del_init(&child->ptrace_list);
- REMOVE_LINKS(child);
- child->parent = child->real_parent;
- SET_LINKS(child);
+ 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);
}
/*
*/
int ptrace_check_attach(struct task_struct *child, int kill)
{
- if (!(child->ptrace & PT_PTRACED))
- return -ESRCH;
-
- if (child->parent != current)
- return -ESRCH;
+ int ret = -ESRCH;
- if (!kill) {
- if (child->state != TASK_STOPPED)
- return -ESRCH;
- wait_task_inactive(child);
+ /*
+ * 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);
/* All systems go.. */
- return 0;
+ return ret;
+}
+
+int __ptrace_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 = __ptrace_may_attach(task);
+ task_unlock(task);
+ return !err;
}
int ptrace_attach(struct task_struct *task)
{
int retval;
- task_lock(task);
+
retval = -EPERM;
if (task->pid <= 1)
- goto bad;
- if (task == current)
- goto bad;
+ 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;
- 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))
- goto bad;
- rmb();
- if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE))
- goto bad;
/* the same process cannot be attached many times */
if (task->ptrace & PT_PTRACED)
goto bad;
- retval = security_ptrace(current, task);
+ retval = __ptrace_may_attach(task);
if (retval)
goto bad;
/* Go */
- task->ptrace |= PT_PTRACED;
+ task->ptrace |= PT_PTRACED | ((task->real_parent != current)
+ ? PT_ATTACHED : 0);
if (capable(CAP_SYS_PTRACE))
task->ptrace |= PT_PTRACE_CAP;
- task_unlock(task);
- write_lock_irq(&tasklist_lock);
__ptrace_link(task, current);
- write_unlock_irq(&tasklist_lock);
force_sig_specific(SIGSTOP, task);
- return 0;
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 ((unsigned long) data > _NSIG)
- return -EIO;
+ if (!valid_signal(data))
+ return -EIO;
/* Architecture-specific hardware disable .. */
ptrace_disable(child);
- /* .. re-parent .. */
- child->exit_code = data;
-
write_lock_irq(&tasklist_lock);
- __ptrace_unlink(child);
- /* .. and wake it up. */
- if (child->state != TASK_ZOMBIE)
- wake_up_process(child);
+ /* protect against de_thread()->release_task() */
+ if (child->ptrace)
+ __ptrace_detach(child, data);
write_unlock_irq(&tasklist_lock);
return 0;
if (bytes > PAGE_SIZE-offset)
bytes = PAGE_SIZE-offset;
- flush_cache_page(vma, addr);
-
maddr = kmap(page);
if (write) {
copy_to_user_page(vma, page, addr,
static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data)
{
- if (child->last_siginfo == NULL)
- return -EINVAL;
- return copy_siginfo_to_user(data, child->last_siginfo);
+ 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)
{
- if (child->last_siginfo == NULL)
- return -EINVAL;
- if (copy_from_user(child->last_siginfo, data, sizeof (siginfo_t)) != 0)
+ siginfo_t newinfo;
+ int error = -ESRCH;
+
+ if (copy_from_user(&newinfo, data, sizeof (siginfo_t)))
return -EFAULT;
- return 0;
+
+ 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,
return ret;
}
-void ptrace_notify(int exit_code)
+/**
+ * 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)
{
- BUG_ON (!(current->ptrace & PT_PTRACED));
-
- /* Let the debugger run. */
- current->exit_code = exit_code;
- set_current_state(TASK_STOPPED);
- notify_parent(current, SIGCHLD);
- schedule();
+ int ret = -EPERM;
/*
- * Signals sent while we were stopped might set TIF_SIGPENDING.
+ * 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;
- spin_lock_irq(¤t->sighand->siglock);
- recalc_sigpending();
- spin_unlock_irq(¤t->sighand->siglock);
+ /*
+ * 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;
}
-EXPORT_SYMBOL(ptrace_notify);
+#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;
+ }
+
+ ret = -EPERM;
+ if (!vx_check(vx_task_xid(child), VX_WATCH|VX_IDENT))
+ goto out_put_task_struct;
+
+ 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 */
git://git.onelab.eu / linux-2.6.git / blobdiff