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-rw-r--r--kernel/pid.c748
1 files changed, 748 insertions, 0 deletions
diff --git a/kernel/pid.c b/kernel/pid.c
new file mode 100644
index 0000000000..6500ef956f
--- /dev/null
+++ b/kernel/pid.c
@@ -0,0 +1,748 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Generic pidhash and scalable, time-bounded PID allocator
+ *
+ * (C) 2002-2003 Nadia Yvette Chambers, IBM
+ * (C) 2004 Nadia Yvette Chambers, Oracle
+ * (C) 2002-2004 Ingo Molnar, Red Hat
+ *
+ * pid-structures are backing objects for tasks sharing a given ID to chain
+ * against. There is very little to them aside from hashing them and
+ * parking tasks using given ID's on a list.
+ *
+ * The hash is always changed with the tasklist_lock write-acquired,
+ * and the hash is only accessed with the tasklist_lock at least
+ * read-acquired, so there's no additional SMP locking needed here.
+ *
+ * We have a list of bitmap pages, which bitmaps represent the PID space.
+ * Allocating and freeing PIDs is completely lockless. The worst-case
+ * allocation scenario when all but one out of 1 million PIDs possible are
+ * allocated already: the scanning of 32 list entries and at most PAGE_SIZE
+ * bytes. The typical fastpath is a single successful setbit. Freeing is O(1).
+ *
+ * Pid namespaces:
+ * (C) 2007 Pavel Emelyanov <xemul@openvz.org>, OpenVZ, SWsoft Inc.
+ * (C) 2007 Sukadev Bhattiprolu <sukadev@us.ibm.com>, IBM
+ * Many thanks to Oleg Nesterov for comments and help
+ *
+ */
+
+#include <linux/mm.h>
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/rculist.h>
+#include <linux/memblock.h>
+#include <linux/pid_namespace.h>
+#include <linux/init_task.h>
+#include <linux/syscalls.h>
+#include <linux/proc_ns.h>
+#include <linux/refcount.h>
+#include <linux/anon_inodes.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/task.h>
+#include <linux/idr.h>
+#include <net/sock.h>
+#include <uapi/linux/pidfd.h>
+
+struct pid init_struct_pid = {
+ .count = REFCOUNT_INIT(1),
+ .tasks = {
+ { .first = NULL },
+ { .first = NULL },
+ { .first = NULL },
+ },
+ .level = 0,
+ .numbers = { {
+ .nr = 0,
+ .ns = &init_pid_ns,
+ }, }
+};
+
+int pid_max = PID_MAX_DEFAULT;
+
+#define RESERVED_PIDS 300
+
+int pid_max_min = RESERVED_PIDS + 1;
+int pid_max_max = PID_MAX_LIMIT;
+
+/*
+ * PID-map pages start out as NULL, they get allocated upon
+ * first use and are never deallocated. This way a low pid_max
+ * value does not cause lots of bitmaps to be allocated, but
+ * the scheme scales to up to 4 million PIDs, runtime.
+ */
+struct pid_namespace init_pid_ns = {
+ .ns.count = REFCOUNT_INIT(2),
+ .idr = IDR_INIT(init_pid_ns.idr),
+ .pid_allocated = PIDNS_ADDING,
+ .level = 0,
+ .child_reaper = &init_task,
+ .user_ns = &init_user_ns,
+ .ns.inum = PROC_PID_INIT_INO,
+#ifdef CONFIG_PID_NS
+ .ns.ops = &pidns_operations,
+#endif
+#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
+ .memfd_noexec_scope = MEMFD_NOEXEC_SCOPE_EXEC,
+#endif
+};
+EXPORT_SYMBOL_GPL(init_pid_ns);
+
+/*
+ * Note: disable interrupts while the pidmap_lock is held as an
+ * interrupt might come in and do read_lock(&tasklist_lock).
+ *
+ * If we don't disable interrupts there is a nasty deadlock between
+ * detach_pid()->free_pid() and another cpu that does
+ * spin_lock(&pidmap_lock) followed by an interrupt routine that does
+ * read_lock(&tasklist_lock);
+ *
+ * After we clean up the tasklist_lock and know there are no
+ * irq handlers that take it we can leave the interrupts enabled.
+ * For now it is easier to be safe than to prove it can't happen.
+ */
+
+static __cacheline_aligned_in_smp DEFINE_SPINLOCK(pidmap_lock);
+
+void put_pid(struct pid *pid)
+{
+ struct pid_namespace *ns;
+
+ if (!pid)
+ return;
+
+ ns = pid->numbers[pid->level].ns;
+ if (refcount_dec_and_test(&pid->count)) {
+ kmem_cache_free(ns->pid_cachep, pid);
+ put_pid_ns(ns);
+ }
+}
+EXPORT_SYMBOL_GPL(put_pid);
+
+static void delayed_put_pid(struct rcu_head *rhp)
+{
+ struct pid *pid = container_of(rhp, struct pid, rcu);
+ put_pid(pid);
+}
+
+void free_pid(struct pid *pid)
+{
+ /* We can be called with write_lock_irq(&tasklist_lock) held */
+ int i;
+ unsigned long flags;
+
+ spin_lock_irqsave(&pidmap_lock, flags);
+ for (i = 0; i <= pid->level; i++) {
+ struct upid *upid = pid->numbers + i;
+ struct pid_namespace *ns = upid->ns;
+ switch (--ns->pid_allocated) {
+ case 2:
+ case 1:
+ /* When all that is left in the pid namespace
+ * is the reaper wake up the reaper. The reaper
+ * may be sleeping in zap_pid_ns_processes().
+ */
+ wake_up_process(ns->child_reaper);
+ break;
+ case PIDNS_ADDING:
+ /* Handle a fork failure of the first process */
+ WARN_ON(ns->child_reaper);
+ ns->pid_allocated = 0;
+ break;
+ }
+
+ idr_remove(&ns->idr, upid->nr);
+ }
+ spin_unlock_irqrestore(&pidmap_lock, flags);
+
+ call_rcu(&pid->rcu, delayed_put_pid);
+}
+
+struct pid *alloc_pid(struct pid_namespace *ns, pid_t *set_tid,
+ size_t set_tid_size)
+{
+ struct pid *pid;
+ enum pid_type type;
+ int i, nr;
+ struct pid_namespace *tmp;
+ struct upid *upid;
+ int retval = -ENOMEM;
+
+ /*
+ * set_tid_size contains the size of the set_tid array. Starting at
+ * the most nested currently active PID namespace it tells alloc_pid()
+ * which PID to set for a process in that most nested PID namespace
+ * up to set_tid_size PID namespaces. It does not have to set the PID
+ * for a process in all nested PID namespaces but set_tid_size must
+ * never be greater than the current ns->level + 1.
+ */
+ if (set_tid_size > ns->level + 1)
+ return ERR_PTR(-EINVAL);
+
+ pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
+ if (!pid)
+ return ERR_PTR(retval);
+
+ tmp = ns;
+ pid->level = ns->level;
+
+ for (i = ns->level; i >= 0; i--) {
+ int tid = 0;
+
+ if (set_tid_size) {
+ tid = set_tid[ns->level - i];
+
+ retval = -EINVAL;
+ if (tid < 1 || tid >= pid_max)
+ goto out_free;
+ /*
+ * Also fail if a PID != 1 is requested and
+ * no PID 1 exists.
+ */
+ if (tid != 1 && !tmp->child_reaper)
+ goto out_free;
+ retval = -EPERM;
+ if (!checkpoint_restore_ns_capable(tmp->user_ns))
+ goto out_free;
+ set_tid_size--;
+ }
+
+ idr_preload(GFP_KERNEL);
+ spin_lock_irq(&pidmap_lock);
+
+ if (tid) {
+ nr = idr_alloc(&tmp->idr, NULL, tid,
+ tid + 1, GFP_ATOMIC);
+ /*
+ * If ENOSPC is returned it means that the PID is
+ * alreay in use. Return EEXIST in that case.
+ */
+ if (nr == -ENOSPC)
+ nr = -EEXIST;
+ } else {
+ int pid_min = 1;
+ /*
+ * init really needs pid 1, but after reaching the
+ * maximum wrap back to RESERVED_PIDS
+ */
+ if (idr_get_cursor(&tmp->idr) > RESERVED_PIDS)
+ pid_min = RESERVED_PIDS;
+
+ /*
+ * Store a null pointer so find_pid_ns does not find
+ * a partially initialized PID (see below).
+ */
+ nr = idr_alloc_cyclic(&tmp->idr, NULL, pid_min,
+ pid_max, GFP_ATOMIC);
+ }
+ spin_unlock_irq(&pidmap_lock);
+ idr_preload_end();
+
+ if (nr < 0) {
+ retval = (nr == -ENOSPC) ? -EAGAIN : nr;
+ goto out_free;
+ }
+
+ pid->numbers[i].nr = nr;
+ pid->numbers[i].ns = tmp;
+ tmp = tmp->parent;
+ }
+
+ /*
+ * ENOMEM is not the most obvious choice especially for the case
+ * where the child subreaper has already exited and the pid
+ * namespace denies the creation of any new processes. But ENOMEM
+ * is what we have exposed to userspace for a long time and it is
+ * documented behavior for pid namespaces. So we can't easily
+ * change it even if there were an error code better suited.
+ */
+ retval = -ENOMEM;
+
+ get_pid_ns(ns);
+ refcount_set(&pid->count, 1);
+ spin_lock_init(&pid->lock);
+ for (type = 0; type < PIDTYPE_MAX; ++type)
+ INIT_HLIST_HEAD(&pid->tasks[type]);
+
+ init_waitqueue_head(&pid->wait_pidfd);
+ INIT_HLIST_HEAD(&pid->inodes);
+
+ upid = pid->numbers + ns->level;
+ spin_lock_irq(&pidmap_lock);
+ if (!(ns->pid_allocated & PIDNS_ADDING))
+ goto out_unlock;
+ for ( ; upid >= pid->numbers; --upid) {
+ /* Make the PID visible to find_pid_ns. */
+ idr_replace(&upid->ns->idr, pid, upid->nr);
+ upid->ns->pid_allocated++;
+ }
+ spin_unlock_irq(&pidmap_lock);
+
+ return pid;
+
+out_unlock:
+ spin_unlock_irq(&pidmap_lock);
+ put_pid_ns(ns);
+
+out_free:
+ spin_lock_irq(&pidmap_lock);
+ while (++i <= ns->level) {
+ upid = pid->numbers + i;
+ idr_remove(&upid->ns->idr, upid->nr);
+ }
+
+ /* On failure to allocate the first pid, reset the state */
+ if (ns->pid_allocated == PIDNS_ADDING)
+ idr_set_cursor(&ns->idr, 0);
+
+ spin_unlock_irq(&pidmap_lock);
+
+ kmem_cache_free(ns->pid_cachep, pid);
+ return ERR_PTR(retval);
+}
+
+void disable_pid_allocation(struct pid_namespace *ns)
+{
+ spin_lock_irq(&pidmap_lock);
+ ns->pid_allocated &= ~PIDNS_ADDING;
+ spin_unlock_irq(&pidmap_lock);
+}
+
+struct pid *find_pid_ns(int nr, struct pid_namespace *ns)
+{
+ return idr_find(&ns->idr, nr);
+}
+EXPORT_SYMBOL_GPL(find_pid_ns);
+
+struct pid *find_vpid(int nr)
+{
+ return find_pid_ns(nr, task_active_pid_ns(current));
+}
+EXPORT_SYMBOL_GPL(find_vpid);
+
+static struct pid **task_pid_ptr(struct task_struct *task, enum pid_type type)
+{
+ return (type == PIDTYPE_PID) ?
+ &task->thread_pid :
+ &task->signal->pids[type];
+}
+
+/*
+ * attach_pid() must be called with the tasklist_lock write-held.
+ */
+void attach_pid(struct task_struct *task, enum pid_type type)
+{
+ struct pid *pid = *task_pid_ptr(task, type);
+ hlist_add_head_rcu(&task->pid_links[type], &pid->tasks[type]);
+}
+
+static void __change_pid(struct task_struct *task, enum pid_type type,
+ struct pid *new)
+{
+ struct pid **pid_ptr = task_pid_ptr(task, type);
+ struct pid *pid;
+ int tmp;
+
+ pid = *pid_ptr;
+
+ hlist_del_rcu(&task->pid_links[type]);
+ *pid_ptr = new;
+
+ for (tmp = PIDTYPE_MAX; --tmp >= 0; )
+ if (pid_has_task(pid, tmp))
+ return;
+
+ free_pid(pid);
+}
+
+void detach_pid(struct task_struct *task, enum pid_type type)
+{
+ __change_pid(task, type, NULL);
+}
+
+void change_pid(struct task_struct *task, enum pid_type type,
+ struct pid *pid)
+{
+ __change_pid(task, type, pid);
+ attach_pid(task, type);
+}
+
+void exchange_tids(struct task_struct *left, struct task_struct *right)
+{
+ struct pid *pid1 = left->thread_pid;
+ struct pid *pid2 = right->thread_pid;
+ struct hlist_head *head1 = &pid1->tasks[PIDTYPE_PID];
+ struct hlist_head *head2 = &pid2->tasks[PIDTYPE_PID];
+
+ /* Swap the single entry tid lists */
+ hlists_swap_heads_rcu(head1, head2);
+
+ /* Swap the per task_struct pid */
+ rcu_assign_pointer(left->thread_pid, pid2);
+ rcu_assign_pointer(right->thread_pid, pid1);
+
+ /* Swap the cached value */
+ WRITE_ONCE(left->pid, pid_nr(pid2));
+ WRITE_ONCE(right->pid, pid_nr(pid1));
+}
+
+/* transfer_pid is an optimization of attach_pid(new), detach_pid(old) */
+void transfer_pid(struct task_struct *old, struct task_struct *new,
+ enum pid_type type)
+{
+ if (type == PIDTYPE_PID)
+ new->thread_pid = old->thread_pid;
+ hlist_replace_rcu(&old->pid_links[type], &new->pid_links[type]);
+}
+
+struct task_struct *pid_task(struct pid *pid, enum pid_type type)
+{
+ struct task_struct *result = NULL;
+ if (pid) {
+ struct hlist_node *first;
+ first = rcu_dereference_check(hlist_first_rcu(&pid->tasks[type]),
+ lockdep_tasklist_lock_is_held());
+ if (first)
+ result = hlist_entry(first, struct task_struct, pid_links[(type)]);
+ }
+ return result;
+}
+EXPORT_SYMBOL(pid_task);
+
+/*
+ * Must be called under rcu_read_lock().
+ */
+struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns)
+{
+ RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
+ "find_task_by_pid_ns() needs rcu_read_lock() protection");
+ return pid_task(find_pid_ns(nr, ns), PIDTYPE_PID);
+}
+
+struct task_struct *find_task_by_vpid(pid_t vnr)
+{
+ return find_task_by_pid_ns(vnr, task_active_pid_ns(current));
+}
+
+struct task_struct *find_get_task_by_vpid(pid_t nr)
+{
+ struct task_struct *task;
+
+ rcu_read_lock();
+ task = find_task_by_vpid(nr);
+ if (task)
+ get_task_struct(task);
+ rcu_read_unlock();
+
+ return task;
+}
+
+struct pid *get_task_pid(struct task_struct *task, enum pid_type type)
+{
+ struct pid *pid;
+ rcu_read_lock();
+ pid = get_pid(rcu_dereference(*task_pid_ptr(task, type)));
+ rcu_read_unlock();
+ return pid;
+}
+EXPORT_SYMBOL_GPL(get_task_pid);
+
+struct task_struct *get_pid_task(struct pid *pid, enum pid_type type)
+{
+ struct task_struct *result;
+ rcu_read_lock();
+ result = pid_task(pid, type);
+ if (result)
+ get_task_struct(result);
+ rcu_read_unlock();
+ return result;
+}
+EXPORT_SYMBOL_GPL(get_pid_task);
+
+struct pid *find_get_pid(pid_t nr)
+{
+ struct pid *pid;
+
+ rcu_read_lock();
+ pid = get_pid(find_vpid(nr));
+ rcu_read_unlock();
+
+ return pid;
+}
+EXPORT_SYMBOL_GPL(find_get_pid);
+
+pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns)
+{
+ struct upid *upid;
+ pid_t nr = 0;
+
+ if (pid && ns->level <= pid->level) {
+ upid = &pid->numbers[ns->level];
+ if (upid->ns == ns)
+ nr = upid->nr;
+ }
+ return nr;
+}
+EXPORT_SYMBOL_GPL(pid_nr_ns);
+
+pid_t pid_vnr(struct pid *pid)
+{
+ return pid_nr_ns(pid, task_active_pid_ns(current));
+}
+EXPORT_SYMBOL_GPL(pid_vnr);
+
+pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
+ struct pid_namespace *ns)
+{
+ pid_t nr = 0;
+
+ rcu_read_lock();
+ if (!ns)
+ ns = task_active_pid_ns(current);
+ nr = pid_nr_ns(rcu_dereference(*task_pid_ptr(task, type)), ns);
+ rcu_read_unlock();
+
+ return nr;
+}
+EXPORT_SYMBOL(__task_pid_nr_ns);
+
+struct pid_namespace *task_active_pid_ns(struct task_struct *tsk)
+{
+ return ns_of_pid(task_pid(tsk));
+}
+EXPORT_SYMBOL_GPL(task_active_pid_ns);
+
+/*
+ * Used by proc to find the first pid that is greater than or equal to nr.
+ *
+ * If there is a pid at nr this function is exactly the same as find_pid_ns.
+ */
+struct pid *find_ge_pid(int nr, struct pid_namespace *ns)
+{
+ return idr_get_next(&ns->idr, &nr);
+}
+EXPORT_SYMBOL_GPL(find_ge_pid);
+
+struct pid *pidfd_get_pid(unsigned int fd, unsigned int *flags)
+{
+ struct fd f;
+ struct pid *pid;
+
+ f = fdget(fd);
+ if (!f.file)
+ return ERR_PTR(-EBADF);
+
+ pid = pidfd_pid(f.file);
+ if (!IS_ERR(pid)) {
+ get_pid(pid);
+ *flags = f.file->f_flags;
+ }
+
+ fdput(f);
+ return pid;
+}
+
+/**
+ * pidfd_get_task() - Get the task associated with a pidfd
+ *
+ * @pidfd: pidfd for which to get the task
+ * @flags: flags associated with this pidfd
+ *
+ * Return the task associated with @pidfd. The function takes a reference on
+ * the returned task. The caller is responsible for releasing that reference.
+ *
+ * Currently, the process identified by @pidfd is always a thread-group leader.
+ * This restriction currently exists for all aspects of pidfds including pidfd
+ * creation (CLONE_PIDFD cannot be used with CLONE_THREAD) and pidfd polling
+ * (only supports thread group leaders).
+ *
+ * Return: On success, the task_struct associated with the pidfd.
+ * On error, a negative errno number will be returned.
+ */
+struct task_struct *pidfd_get_task(int pidfd, unsigned int *flags)
+{
+ unsigned int f_flags;
+ struct pid *pid;
+ struct task_struct *task;
+
+ pid = pidfd_get_pid(pidfd, &f_flags);
+ if (IS_ERR(pid))
+ return ERR_CAST(pid);
+
+ task = get_pid_task(pid, PIDTYPE_TGID);
+ put_pid(pid);
+ if (!task)
+ return ERR_PTR(-ESRCH);
+
+ *flags = f_flags;
+ return task;
+}
+
+/**
+ * pidfd_create() - Create a new pid file descriptor.
+ *
+ * @pid: struct pid that the pidfd will reference
+ * @flags: flags to pass
+ *
+ * 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.
+ *
+ * This symbol should not be explicitly exported to loadable modules.
+ *
+ * Return: On success, a cloexec pidfd is returned.
+ * On error, a negative errno number will be returned.
+ */
+int pidfd_create(struct pid *pid, unsigned int flags)
+{
+ int pidfd;
+ struct file *pidfd_file;
+
+ pidfd = pidfd_prepare(pid, flags, &pidfd_file);
+ if (pidfd < 0)
+ return pidfd;
+
+ fd_install(pidfd, pidfd_file);
+ return pidfd;
+}
+
+/**
+ * sys_pidfd_open() - Open new pid file descriptor.
+ *
+ * @pid: pid for which to retrieve a pidfd
+ * @flags: flags to pass
+ *
+ * This creates a new pid file descriptor with the O_CLOEXEC flag set for
+ * the process identified by @pid. Currently, the process identified by
+ * @pid must be a thread-group leader. This restriction currently exists
+ * for all aspects of pidfds including pidfd creation (CLONE_PIDFD cannot
+ * be used with CLONE_THREAD) and pidfd polling (only supports thread group
+ * leaders).
+ *
+ * Return: On success, a cloexec pidfd is returned.
+ * On error, a negative errno number will be returned.
+ */
+SYSCALL_DEFINE2(pidfd_open, pid_t, pid, unsigned int, flags)
+{
+ int fd;
+ struct pid *p;
+
+ if (flags & ~PIDFD_NONBLOCK)
+ return -EINVAL;
+
+ if (pid <= 0)
+ return -EINVAL;
+
+ p = find_get_pid(pid);
+ if (!p)
+ return -ESRCH;
+
+ fd = pidfd_create(p, flags);
+
+ put_pid(p);
+ return fd;
+}
+
+void __init pid_idr_init(void)
+{
+ /* Verify no one has done anything silly: */
+ BUILD_BUG_ON(PID_MAX_LIMIT >= PIDNS_ADDING);
+
+ /* bump default and minimum pid_max based on number of cpus */
+ pid_max = min(pid_max_max, max_t(int, pid_max,
+ PIDS_PER_CPU_DEFAULT * num_possible_cpus()));
+ pid_max_min = max_t(int, pid_max_min,
+ PIDS_PER_CPU_MIN * num_possible_cpus());
+ pr_info("pid_max: default: %u minimum: %u\n", pid_max, pid_max_min);
+
+ idr_init(&init_pid_ns.idr);
+
+ init_pid_ns.pid_cachep = kmem_cache_create("pid",
+ struct_size_t(struct pid, numbers, 1),
+ __alignof__(struct pid),
+ SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT,
+ NULL);
+}
+
+static struct file *__pidfd_fget(struct task_struct *task, int fd)
+{
+ struct file *file;
+ int ret;
+
+ ret = down_read_killable(&task->signal->exec_update_lock);
+ if (ret)
+ return ERR_PTR(ret);
+
+ if (ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS))
+ file = fget_task(task, fd);
+ else
+ file = ERR_PTR(-EPERM);
+
+ up_read(&task->signal->exec_update_lock);
+
+ return file ?: ERR_PTR(-EBADF);
+}
+
+static int pidfd_getfd(struct pid *pid, int fd)
+{
+ struct task_struct *task;
+ struct file *file;
+ int ret;
+
+ task = get_pid_task(pid, PIDTYPE_PID);
+ if (!task)
+ return -ESRCH;
+
+ file = __pidfd_fget(task, fd);
+ put_task_struct(task);
+ if (IS_ERR(file))
+ return PTR_ERR(file);
+
+ ret = receive_fd(file, O_CLOEXEC);
+ fput(file);
+
+ return ret;
+}
+
+/**
+ * sys_pidfd_getfd() - Get a file descriptor from another process
+ *
+ * @pidfd: the pidfd file descriptor of the process
+ * @fd: the file descriptor number to get
+ * @flags: flags on how to get the fd (reserved)
+ *
+ * This syscall gets a copy of a file descriptor from another process
+ * based on the pidfd, and file descriptor number. It requires that
+ * the calling process has the ability to ptrace the process represented
+ * by the pidfd. The process which is having its file descriptor copied
+ * is otherwise unaffected.
+ *
+ * Return: On success, a cloexec file descriptor is returned.
+ * On error, a negative errno number will be returned.
+ */
+SYSCALL_DEFINE3(pidfd_getfd, int, pidfd, int, fd,
+ unsigned int, flags)
+{
+ struct pid *pid;
+ struct fd f;
+ int ret;
+
+ /* flags is currently unused - make sure it's unset */
+ if (flags)
+ return -EINVAL;
+
+ f = fdget(pidfd);
+ if (!f.file)
+ return -EBADF;
+
+ pid = pidfd_pid(f.file);
+ if (IS_ERR(pid))
+ ret = PTR_ERR(pid);
+ else
+ ret = pidfd_getfd(pid, fd);
+
+ fdput(f);
+ return ret;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-05 11:45:08 +0000