1 files changed, 185 insertions, 40 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index 129de589599c..dfa78985a6fd 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -897,6 +897,8 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
 #ifdef CONFIG_STACKPROTECTOR
 	tsk->stack_canary = get_random_canary();
 #endif
+	if (orig->cpus_ptr == &orig->cpus_mask)
+		tsk->cpus_ptr = &tsk->cpus_mask;
 
 	/*
 	 * One for us, one for whoever does the "release_task()" (usually
@@ -1708,8 +1710,34 @@ static void pidfd_show_fdinfo(struct seq_file *m, struct file *f)
 }
 #endif
 
+/*
+ * Poll support for process exit notification.
+ */
+static unsigned int pidfd_poll(struct file *file, struct poll_table_struct *pts)
+{
+	struct task_struct *task;
+	struct pid *pid = file->private_data;
+	int poll_flags = 0;
+
+	poll_wait(file, &pid->wait_pidfd, pts);
+
+	rcu_read_lock();
+	task = pid_task(pid, PIDTYPE_PID);
+	/*
+	 * Inform pollers only when the whole thread group exits.
+	 * If the thread group leader exits before all other threads in the
+	 * group, then poll(2) should block, similar to the wait(2) family.
+	 */
+	if (!task || (task->exit_state && thread_group_empty(task)))
+		poll_flags = POLLIN | POLLRDNORM;
+	rcu_read_unlock();
+
+	return poll_flags;
+}
+
 const struct file_operations pidfd_fops = {
 	.release = pidfd_release,
+	.poll = pidfd_poll,
 #ifdef CONFIG_PROC_FS
 	.show_fdinfo = pidfd_show_fdinfo,
 #endif
@@ -1739,20 +1767,16 @@ static __always_inline void delayed_free_task(struct task_struct *tsk)
  * flags). The actual kick-off is left to the caller.
  */
 static __latent_entropy struct task_struct *copy_process(
-					unsigned long clone_flags,
-					unsigned long stack_start,
-					unsigned long stack_size,
-					int __user *parent_tidptr,
-					int __user *child_tidptr,
 					struct pid *pid,
 					int trace,
-					unsigned long tls,
-					int node)
+					int node,
+					struct kernel_clone_args *args)
 {
 	int pidfd = -1, retval;
 	struct task_struct *p;
 	struct multiprocess_signals delayed;
 	struct file *pidfile = NULL;
+	u64 clone_flags = args->flags;
 
 	/*
 	 * Don't allow sharing the root directory with processes in a different
@@ -1802,14 +1826,11 @@ static __latent_entropy struct task_struct *copy_process(
 
 	if (clone_flags & CLONE_PIDFD) {
 		/*
-		 * - CLONE_PARENT_SETTID is useless for pidfds and also
-		 *   parent_tidptr is used to return pidfds.
 		 * - CLONE_DETACHED is blocked so that we can potentially
 		 *   reuse it later for CLONE_PIDFD.
 		 * - CLONE_THREAD is blocked until someone really needs it.
 		 */
-		if (clone_flags &
-		    (CLONE_DETACHED | CLONE_PARENT_SETTID | CLONE_THREAD))
+		if (clone_flags & (CLONE_DETACHED | CLONE_THREAD))
 			return ERR_PTR(-EINVAL);
 	}
 
@@ -1842,11 +1863,11 @@ static __latent_entropy struct task_struct *copy_process(
 	 * p->set_child_tid which is (ab)used as a kthread's data pointer for
 	 * kernel threads (PF_KTHREAD).
 	 */
-	p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
+	p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? args->child_tid : NULL;
 	/*
 	 * Clear TID on mm_release()?
 	 */
-	p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL;
+	p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? args->child_tid : NULL;
 
 	ftrace_graph_init_task(p);
 
@@ -1951,9 +1972,6 @@ static __latent_entropy struct task_struct *copy_process(
 	p->pagefault_disabled = 0;
 
 #ifdef CONFIG_LOCKDEP
-	p->lockdep_depth = 0; /* no locks held yet */
-	p->curr_chain_key = 0;
-	p->lockdep_recursion = 0;
 	lockdep_init_task(p);
 #endif
 
@@ -2005,7 +2023,8 @@ static __latent_entropy struct task_struct *copy_process(
 	retval = copy_io(clone_flags, p);
 	if (retval)
 		goto bad_fork_cleanup_namespaces;
-	retval = copy_thread_tls(clone_flags, stack_start, stack_size, p, tls);
+	retval = copy_thread_tls(clone_flags, args->stack, args->stack_size, p,
+				 args->tls);
 	if (retval)
 		goto bad_fork_cleanup_io;
 
@@ -2035,11 +2054,12 @@ static __latent_entropy struct task_struct *copy_process(
 					      O_RDWR | O_CLOEXEC);
 		if (IS_ERR(pidfile)) {
 			put_unused_fd(pidfd);
+			retval = PTR_ERR(pidfile);
 			goto bad_fork_free_pid;
 		}
 		get_pid(pid);	/* held by pidfile now */
 
-		retval = put_user(pidfd, parent_tidptr);
+		retval = put_user(pidfd, args->pidfd);
 		if (retval)
 			goto bad_fork_put_pidfd;
 	}
@@ -2082,7 +2102,7 @@ static __latent_entropy struct task_struct *copy_process(
 		if (clone_flags & CLONE_PARENT)
 			p->exit_signal = current->group_leader->exit_signal;
 		else
-			p->exit_signal = (clone_flags & CSIGNAL);
+			p->exit_signal = args->exit_signal;
 		p->group_leader = p;
 		p->tgid = p->pid;
 	}
@@ -2115,7 +2135,7 @@ static __latent_entropy struct task_struct *copy_process(
 	 */
 
 	p->start_time = ktime_get_ns();
-	p->real_start_time = ktime_get_boot_ns();
+	p->real_start_time = ktime_get_boottime_ns();
 
 	/*
 	 * Make it visible to the rest of the system, but dont wake it up yet.
@@ -2295,8 +2315,11 @@ static inline void init_idle_pids(struct task_struct *idle)
 struct task_struct *fork_idle(int cpu)
 {
 	struct task_struct *task;
-	task = copy_process(CLONE_VM, 0, 0, NULL, NULL, &init_struct_pid, 0, 0,
-			    cpu_to_node(cpu));
+	struct kernel_clone_args args = {
+		.flags = CLONE_VM,
+	};
+
+	task = copy_process(&init_struct_pid, 0, cpu_to_node(cpu), &args);
 	if (!IS_ERR(task)) {
 		init_idle_pids(task);
 		init_idle(task, cpu);
@@ -2316,13 +2339,9 @@ struct mm_struct *copy_init_mm(void)
  * It copies the process, and if successful kick-starts
  * it and waits for it to finish using the VM if required.
  */
-long _do_fork(unsigned long clone_flags,
-	      unsigned long stack_start,
-	      unsigned long stack_size,
-	      int __user *parent_tidptr,
-	      int __user *child_tidptr,
-	      unsigned long tls)
+long _do_fork(struct kernel_clone_args *args)
 {
+	u64 clone_flags = args->flags;
 	struct completion vfork;
 	struct pid *pid;
 	struct task_struct *p;
@@ -2338,7 +2357,7 @@ long _do_fork(unsigned long clone_flags,
 	if (!(clone_flags & CLONE_UNTRACED)) {
 		if (clone_flags & CLONE_VFORK)
 			trace = PTRACE_EVENT_VFORK;
-		else if ((clone_flags & CSIGNAL) != SIGCHLD)
+		else if (args->exit_signal != SIGCHLD)
 			trace = PTRACE_EVENT_CLONE;
 		else
 			trace = PTRACE_EVENT_FORK;
@@ -2347,8 +2366,7 @@ long _do_fork(unsigned long clone_flags,
 			trace = 0;
 	}
 
-	p = copy_process(clone_flags, stack_start, stack_size, parent_tidptr,
-			 child_tidptr, NULL, trace, tls, NUMA_NO_NODE);
+	p = copy_process(NULL, trace, NUMA_NO_NODE, args);
 	add_latent_entropy();
 
 	if (IS_ERR(p))
@@ -2364,7 +2382,7 @@ long _do_fork(unsigned long clone_flags,
 	nr = pid_vnr(pid);
 
 	if (clone_flags & CLONE_PARENT_SETTID)
-		put_user(nr, parent_tidptr);
+		put_user(nr, args->parent_tid);
 
 	if (clone_flags & CLONE_VFORK) {
 		p->vfork_done = &vfork;
@@ -2396,8 +2414,16 @@ long do_fork(unsigned long clone_flags,
 	      int __user *parent_tidptr,
 	      int __user *child_tidptr)
 {
-	return _do_fork(clone_flags, stack_start, stack_size,
-			parent_tidptr, child_tidptr, 0);
+	struct kernel_clone_args args = {
+		.flags		= (clone_flags & ~CSIGNAL),
+		.child_tid	= child_tidptr,
+		.parent_tid	= parent_tidptr,
+		.exit_signal	= (clone_flags & CSIGNAL),
+		.stack		= stack_start,
+		.stack_size	= stack_size,
+	};
+
+	return _do_fork(&args);
 }
 #endif
 
@@ -2406,15 +2432,25 @@ long do_fork(unsigned long clone_flags,
  */
 pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 {
-	return _do_fork(flags|CLONE_VM|CLONE_UNTRACED, (unsigned long)fn,
-		(unsigned long)arg, NULL, NULL, 0);
+	struct kernel_clone_args args = {
+		.flags		= ((flags | CLONE_VM | CLONE_UNTRACED) & ~CSIGNAL),
+		.exit_signal	= (flags & CSIGNAL),
+		.stack		= (unsigned long)fn,
+		.stack_size	= (unsigned long)arg,
+	};
+
+	return _do_fork(&args);
 }
 
 #ifdef __ARCH_WANT_SYS_FORK
 SYSCALL_DEFINE0(fork)
 {
 #ifdef CONFIG_MMU
-	return _do_fork(SIGCHLD, 0, 0, NULL, NULL, 0);
+	struct kernel_clone_args args = {
+		.exit_signal = SIGCHLD,
+	};
+
+	return _do_fork(&args);
 #else
 	/* can not support in nommu mode */
 	return -EINVAL;
@@ -2425,8 +2461,12 @@ SYSCALL_DEFINE0(fork)
 #ifdef __ARCH_WANT_SYS_VFORK
 SYSCALL_DEFINE0(vfork)
 {
-	return _do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 0,
-			0, NULL, NULL, 0);
+	struct kernel_clone_args args = {
+		.flags		= CLONE_VFORK | CLONE_VM,
+		.exit_signal	= SIGCHLD,
+	};
+
+	return _do_fork(&args);
 }
 #endif
 
@@ -2454,7 +2494,112 @@ SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
 		 unsigned long, tls)
 #endif
 {
-	return _do_fork(clone_flags, newsp, 0, parent_tidptr, child_tidptr, tls);
+	struct kernel_clone_args args = {
+		.flags		= (clone_flags & ~CSIGNAL),
+		.pidfd		= parent_tidptr,
+		.child_tid	= child_tidptr,
+		.parent_tid	= parent_tidptr,
+		.exit_signal	= (clone_flags & CSIGNAL),
+		.stack		= newsp,
+		.tls		= tls,
+	};
+
+	/* clone(CLONE_PIDFD) uses parent_tidptr to return a pidfd */
+	if ((clone_flags & CLONE_PIDFD) && (clone_flags & CLONE_PARENT_SETTID))
+		return -EINVAL;
+
+	return _do_fork(&args);
+}
+#endif
+
+#ifdef __ARCH_WANT_SYS_CLONE3
+noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
+					      struct clone_args __user *uargs,
+					      size_t size)
+{
+	struct clone_args args;
+
+	if (unlikely(size > PAGE_SIZE))
+		return -E2BIG;
+
+	if (unlikely(size < sizeof(struct clone_args)))
+		return -EINVAL;
+
+	if (unlikely(!access_ok(uargs, size)))
+		return -EFAULT;
+
+	if (size > sizeof(struct clone_args)) {
+		unsigned char __user *addr;
+		unsigned char __user *end;
+		unsigned char val;
+
+		addr = (void __user *)uargs + sizeof(struct clone_args);
+		end = (void __user *)uargs + size;
+
+		for (; addr < end; addr++) {
+			if (get_user(val, addr))
+				return -EFAULT;
+			if (val)
+				return -E2BIG;
+		}
+
+		size = sizeof(struct clone_args);
+	}
+
+	if (copy_from_user(&args, uargs, size))
+		return -EFAULT;
+
+	*kargs = (struct kernel_clone_args){
+		.flags		= args.flags,
+		.pidfd		= u64_to_user_ptr(args.pidfd),
+		.child_tid	= u64_to_user_ptr(args.child_tid),
+		.parent_tid	= u64_to_user_ptr(args.parent_tid),
+		.exit_signal	= args.exit_signal,
+		.stack		= args.stack,
+		.stack_size	= args.stack_size,
+		.tls		= args.tls,
+	};
+
+	return 0;
+}
+
+static bool clone3_args_valid(const struct kernel_clone_args *kargs)
+{
+	/*
+	 * All lower bits of the flag word are taken.
+	 * Verify that no other unknown flags are passed along.
+	 */
+	if (kargs->flags & ~CLONE_LEGACY_FLAGS)
+		return false;
+
+	/*
+	 * - make the CLONE_DETACHED bit reuseable for clone3
+	 * - make the CSIGNAL bits reuseable for clone3
+	 */
+	if (kargs->flags & (CLONE_DETACHED | CSIGNAL))
+		return false;
+
+	if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) &&
+	    kargs->exit_signal)
+		return false;
+
+	return true;
+}
+
+SYSCALL_DEFINE2(clone3, struct clone_args __user *, uargs, size_t, size)
+{
+	int err;
+
+	struct kernel_clone_args kargs;
+
+	err = copy_clone_args_from_user(&kargs, uargs, size);
+	if (err)
+		return err;
+
+	if (!clone3_args_valid(&kargs))
+		return -EINVAL;
+
+	return _do_fork(&kargs);
 }
 #endif