diff options
Diffstat (limited to 'kernel/ptrace.c')
-rw-r--r-- | kernel/ptrace.c | 178 |
1 files changed, 62 insertions, 116 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 42c317874cf..082c320e4db 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -25,16 +25,6 @@ /* - * Initialize a new task whose father had been ptraced. - * - * Called from copy_process(). - */ -void ptrace_fork(struct task_struct *child, unsigned long clone_flags) -{ - arch_ptrace_fork(child, clone_flags); -} - -/* * ptrace a task: make the debugger its new parent and * move it to the ptrace list. * @@ -177,66 +167,82 @@ bool ptrace_may_access(struct task_struct *task, unsigned int mode) 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; - /* Protect exec's credential calculations against our interference; - * SUID, SGID and LSM creds get determined differently under ptrace. + /* + * Protect exec's credential calculations against our interference; + * interference; SUID, SGID and LSM creds get determined differently + * under ptrace. */ - retval = mutex_lock_interruptible(&task->cred_exec_mutex); - if (retval < 0) + retval = -ERESTARTNOINTR; + if (mutex_lock_interruptible(&task->cred_guard_mutex)) goto out; - retval = -EPERM; -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); - if (!write_trylock_irqsave(&tasklist_lock, flags)) { - 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 = __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); - mutex_unlock(&task->cred_exec_mutex); + + retval = 0; +unlock_tasklist: + write_unlock_irq(&tasklist_lock); +unlock_creds: + mutex_unlock(&task->cred_guard_mutex); out: return retval; } +/** + * 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. */ @@ -418,37 +424,33 @@ static int ptrace_setoptions(struct task_struct *child, long data) 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; } @@ -575,72 +577,16 @@ int ptrace_request(struct task_struct *child, long request, 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? - */ -repeat: - task_lock(current); - if (!(current->ptrace & PT_PTRACED)) { - /* - * See ptrace_attach() comments about the locking here. - */ - unsigned long flags; - if (!write_trylock_irqsave(&tasklist_lock, flags)) { - task_unlock(current); - do { - cpu_relax(); - } while (!write_can_lock(&tasklist_lock)); - goto repeat; - } - - 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_irqrestore(&tasklist_lock, flags); - } - 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; |