From cdefbf2324ceda662e2667aa2f44e8b9de3d780f Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Thu, 25 Jan 2024 17:17:34 +0100 Subject: [PATCH] pidfd: cleanup the usage of __pidfd_prepare's flags - make pidfd_create() static. - Don't pass O_RDWR | O_CLOEXEC to __pidfd_prepare() in copy_process(), __pidfd_prepare() adds these flags unconditionally. - Kill the flags check in __pidfd_prepare(). sys_pidfd_open() checks the flags itself, all other users of pidfd_prepare() pass flags = 0. If we need a sanity check for those other in kernel users then WARN_ON_ONCE(flags & ~PIDFD_NONBLOCK) makes more sense. - Don't pass O_RDWR to get_unused_fd_flags(), it ignores everything except O_CLOEXEC. - Don't pass O_CLOEXEC to anon_inode_getfile(), it ignores everything except O_ACCMODE | O_NONBLOCK. Signed-off-by: Oleg Nesterov Link: https://lore.kernel.org/r/20240125161734.GA778@redhat.com Signed-off-by: Christian Brauner --- include/linux/pid.h | 1 - kernel/fork.c | 9 +++------ kernel/pid.c | 2 +- 3 files changed, 4 insertions(+), 8 deletions(-) diff --git a/include/linux/pid.h b/include/linux/pid.h index 395cacce1179..e6a041cb8bac 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -73,7 +73,6 @@ struct file; extern struct pid *pidfd_pid(const struct file *file); struct pid *pidfd_get_pid(unsigned int fd, unsigned int *flags); struct task_struct *pidfd_get_task(int pidfd, unsigned int *flags); -int pidfd_create(struct pid *pid, unsigned int flags); int pidfd_prepare(struct pid *pid, unsigned int flags, struct file **ret); static inline struct pid *get_pid(struct pid *pid) diff --git a/kernel/fork.c b/kernel/fork.c index 95647c66309f..726a92043531 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -2130,15 +2130,12 @@ static int __pidfd_prepare(struct pid *pid, unsigned int flags, struct file **re int pidfd; struct file *pidfd_file; - if (flags & ~(O_NONBLOCK | O_RDWR | O_CLOEXEC)) - return -EINVAL; - - pidfd = get_unused_fd_flags(O_RDWR | O_CLOEXEC); + pidfd = get_unused_fd_flags(O_CLOEXEC); if (pidfd < 0) return pidfd; pidfd_file = anon_inode_getfile("[pidfd]", &pidfd_fops, pid, - flags | O_RDWR | O_CLOEXEC); + flags | O_RDWR); if (IS_ERR(pidfd_file)) { put_unused_fd(pidfd); return PTR_ERR(pidfd_file); @@ -2524,7 +2521,7 @@ __latent_entropy struct task_struct *copy_process( */ if (clone_flags & CLONE_PIDFD) { /* Note that no task has been attached to @pid yet. */ - retval = __pidfd_prepare(pid, O_RDWR | O_CLOEXEC, &pidfile); + retval = __pidfd_prepare(pid, 0, &pidfile); if (retval < 0) goto bad_fork_free_pid; pidfd = retval; diff --git a/kernel/pid.c b/kernel/pid.c index b52b10865454..c7a3e359f8f5 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -595,7 +595,7 @@ struct task_struct *pidfd_get_task(int pidfd, unsigned int *flags) * 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) +static int pidfd_create(struct pid *pid, unsigned int flags) { int pidfd; struct file *pidfd_file;