diff options
Diffstat (limited to 'kernel/fork.c')
| -rw-r--r-- | kernel/fork.c | 196 |
1 files changed, 156 insertions, 40 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index 58514ce46152..c25ebf6dd7f9 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -11,6 +11,7 @@ * management can be a bitch. See 'mm/memory.c': 'copy_page_range()' */ +#include <linux/anon_inodes.h> #include <linux/slab.h> #include <linux/init.h> #include <linux/unistd.h> @@ -38,6 +39,7 @@ #include <linux/security.h> #include <linux/hugetlb.h> #include <linux/seccomp.h> +#include <linux/seq_file.h> #include <linux/swap.h> #include <linux/syscalls.h> #include <linux/jiffies.h> @@ -619,6 +621,7 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p, mm->pinned_vm = 0; memset(&mm->rss_stat, 0, sizeof(mm->rss_stat)); spin_lock_init(&mm->page_table_lock); + spin_lock_init(&mm->arg_lock); mm_init_cpumask(mm); mm_init_aio(mm); mm_init_owner(mm, p); @@ -920,24 +923,8 @@ static int wait_for_vfork_done(struct task_struct *child, * restoring the old one. . . * Eric Biederman 10 January 1998 */ -void mm_release(struct task_struct *tsk, struct mm_struct *mm) +static void mm_release(struct task_struct *tsk, struct mm_struct *mm) { - /* Get rid of any futexes when releasing the mm */ -#ifdef CONFIG_FUTEX - if (unlikely(tsk->robust_list)) { - exit_robust_list(tsk); - tsk->robust_list = NULL; - } -#ifdef CONFIG_COMPAT - if (unlikely(tsk->compat_robust_list)) { - compat_exit_robust_list(tsk); - tsk->compat_robust_list = NULL; - } -#endif - if (unlikely(!list_empty(&tsk->pi_state_list))) - exit_pi_state_list(tsk); -#endif - uprobe_free_utask(tsk); /* Get rid of any cached register state */ @@ -970,6 +957,18 @@ void mm_release(struct task_struct *tsk, struct mm_struct *mm) complete_vfork_done(tsk); } +void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm) +{ + futex_exit_release(tsk); + mm_release(tsk, mm); +} + +void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm) +{ + futex_exec_release(tsk); + mm_release(tsk, mm); +} + /* * Allocate a new mm structure and copy contents from the * mm structure of the passed in task structure. @@ -1298,6 +1297,84 @@ init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid) task->pids[type].pid = pid; } +static int pidfd_release(struct inode *inode, struct file *file) +{ + struct pid *pid = file->private_data; + + file->private_data = NULL; + put_pid(pid); + return 0; +} + +#ifdef CONFIG_PROC_FS +static void pidfd_show_fdinfo(struct seq_file *m, struct file *f) +{ + struct pid_namespace *ns = file_inode(m->file)->i_sb->s_fs_info; + struct pid *pid = f->private_data; + + seq_put_decimal_ull(m, "Pid:\t", pid_nr_ns(pid, ns)); + seq_putc(m, '\n'); +} +#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 +}; + +/** + * pidfd_create() - Create a new pid file descriptor. + * + * @pid: struct pid that the pidfd will reference + * + * This creates a new pid file descriptor with the O_CLOEXEC flag set. + * + * Note, that this function can only be called after the fd table has + * been unshared to avoid leaking the pidfd to the new process. + * + * Return: On success, a cloexec pidfd is returned. + * On error, a negative errno number will be returned. + */ +static int pidfd_create(struct pid *pid) +{ + int fd; + + fd = anon_inode_getfd("[pidfd]", &pidfd_fops, get_pid(pid), + O_RDWR | O_CLOEXEC); + if (fd < 0) + put_pid(pid); + + return fd; +} + /* * This creates a new process as a copy of the old one, * but does not actually start it yet. @@ -1309,15 +1386,15 @@ init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid) static 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 retval; + int pidfd = -1, retval; struct task_struct *p; - void *cgrp_ss_priv[CGROUP_CANFORK_COUNT] = {}; if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) return ERR_PTR(-EINVAL); @@ -1361,6 +1438,31 @@ static struct task_struct *copy_process(unsigned long clone_flags, return ERR_PTR(-EINVAL); } + if (clone_flags & CLONE_PIDFD) { + int reserved; + + /* + * - 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)) + return ERR_PTR(-EINVAL); + + /* + * Verify that parent_tidptr is sane so we can potentially + * reuse it later. + */ + if (get_user(reserved, parent_tidptr)) + return ERR_PTR(-EFAULT); + + if (reserved != 0) + return ERR_PTR(-EINVAL); + } + retval = security_task_create(clone_flags); if (retval) goto fork_out; @@ -1543,17 +1645,27 @@ static struct task_struct *copy_process(unsigned long clone_flags, } } + /* + * This has to happen after we've potentially unshared the file + * descriptor table (so that the pidfd doesn't leak into the child + * if the fd table isn't shared). + */ + if (clone_flags & CLONE_PIDFD) { + retval = pidfd_create(pid); + if (retval < 0) + goto bad_fork_free_pid; + + pidfd = retval; + retval = put_user(pidfd, parent_tidptr); + if (retval) + goto bad_fork_put_pidfd; + } + #ifdef CONFIG_BLOCK p->plug = NULL; #endif -#ifdef CONFIG_FUTEX - p->robust_list = NULL; -#ifdef CONFIG_COMPAT - p->compat_robust_list = NULL; -#endif - INIT_LIST_HEAD(&p->pi_state_list); - p->pi_state_cache = NULL; -#endif + futex_init_task(p); + /* * sigaltstack should be cleared when sharing the same VM */ @@ -1574,14 +1686,9 @@ static struct task_struct *copy_process(unsigned long clone_flags, /* ok, now we should be set up.. */ p->pid = pid_nr(pid); if (clone_flags & CLONE_THREAD) { - p->exit_signal = -1; p->group_leader = current->group_leader; p->tgid = current->tgid; } else { - if (clone_flags & CLONE_PARENT) - p->exit_signal = current->group_leader->exit_signal; - else - p->exit_signal = (clone_flags & CSIGNAL); p->group_leader = p; p->tgid = p->pid; } @@ -1601,9 +1708,9 @@ static struct task_struct *copy_process(unsigned long clone_flags, * between here and cgroup_post_fork() if an organisation operation is in * progress. */ - retval = cgroup_can_fork(p, cgrp_ss_priv); + retval = cgroup_can_fork(p); if (retval) - goto bad_fork_free_pid; + goto bad_fork_cgroup_threadgroup_change_end; /* * From this point on we must avoid any synchronous user-space @@ -1626,9 +1733,14 @@ static struct task_struct *copy_process(unsigned long clone_flags, if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) { p->real_parent = current->real_parent; p->parent_exec_id = current->parent_exec_id; + if (clone_flags & CLONE_THREAD) + p->exit_signal = -1; + else + p->exit_signal = current->group_leader->exit_signal; } else { p->real_parent = current; p->parent_exec_id = current->self_exec_id; + p->exit_signal = (clone_flags & CSIGNAL); } spin_lock(¤t->sighand->siglock); @@ -1696,7 +1808,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, write_unlock_irq(&tasklist_lock); proc_fork_connector(p); - cgroup_post_fork(p, cgrp_ss_priv); + cgroup_post_fork(p); threadgroup_change_end(current); perf_event_fork(p); @@ -1708,9 +1820,13 @@ static struct task_struct *copy_process(unsigned long clone_flags, bad_fork_cancel_cgroup: spin_unlock(¤t->sighand->siglock); write_unlock_irq(&tasklist_lock); - cgroup_cancel_fork(p, cgrp_ss_priv); + cgroup_cancel_fork(p); +bad_fork_cgroup_threadgroup_change_end: + cgroup_threadgroup_change_end(current); +bad_fork_put_pidfd: + if (clone_flags & CLONE_PIDFD) + sys_close(pidfd); bad_fork_free_pid: - threadgroup_change_end(current); if (pid != &init_struct_pid) free_pid(pid); bad_fork_cleanup_io: @@ -1765,7 +1881,7 @@ static inline void init_idle_pids(struct pid_link *links) struct task_struct *fork_idle(int cpu) { struct task_struct *task; - task = copy_process(CLONE_VM, 0, 0, NULL, &init_struct_pid, 0, 0, + task = copy_process(CLONE_VM, 0, 0, NULL, NULL, &init_struct_pid, 0, 0, cpu_to_node(cpu)); if (!IS_ERR(task)) { init_idle_pids(task->pids); @@ -1810,7 +1926,7 @@ long _do_fork(unsigned long clone_flags, trace = 0; } - p = copy_process(clone_flags, stack_start, stack_size, + p = copy_process(clone_flags, stack_start, stack_size, parent_tidptr, child_tidptr, NULL, trace, tls, NUMA_NO_NODE); /* * Do this prior waking up the new thread - the thread pointer @@ -1975,7 +2091,7 @@ static int check_unshare_flags(unsigned long unshare_flags) if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND| CLONE_VM|CLONE_FILES|CLONE_SYSVSEM| CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET| - CLONE_NEWUSER|CLONE_NEWPID)) + CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP)) return -EINVAL; /* * Not implemented, but pretend it works if there is nothing |