diff options
| -rw-r--r-- | fs/proc/base.c | 3 | ||||
| -rw-r--r-- | kernel/fork.c | 58 | ||||
| -rw-r--r-- | samples/pidfd/pidfd-metadata.c | 8 |
3 files changed, 25 insertions, 44 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index 9c8ca6cd3ce4..255f6754c70d 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -3077,8 +3077,7 @@ static const struct file_operations proc_tgid_base_operations = { struct pid *tgid_pidfd_to_pid(const struct file *file) { - if (!d_is_dir(file->f_path.dentry) || - (file->f_op != &proc_tgid_base_operations)) + if (file->f_op != &proc_tgid_base_operations) return ERR_PTR(-EBADF); return proc_pid(file_inode(file)); diff --git a/kernel/fork.c b/kernel/fork.c index 75675b9bf6df..399aca51ff75 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1712,31 +1712,6 @@ const struct file_operations pidfd_fops = { #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; -} - static void __delayed_free_task(struct rcu_head *rhp) { struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); @@ -1774,6 +1749,7 @@ static __latent_entropy struct task_struct *copy_process( int pidfd = -1, retval; struct task_struct *p; struct multiprocess_signals delayed; + struct file *pidfile = NULL; /* * Don't allow sharing the root directory with processes in a different @@ -1822,8 +1798,6 @@ static __latent_entropy struct task_struct *copy_process( } if (clone_flags & CLONE_PIDFD) { - int reserved; - /* * - CLONE_PARENT_SETTID is useless for pidfds and also * parent_tidptr is used to return pidfds. @@ -1834,16 +1808,6 @@ static __latent_entropy struct task_struct *copy_process( 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); } /* @@ -2058,11 +2022,20 @@ static __latent_entropy struct task_struct *copy_process( * if the fd table isn't shared). */ if (clone_flags & CLONE_PIDFD) { - retval = pidfd_create(pid); + retval = get_unused_fd_flags(O_RDWR | O_CLOEXEC); if (retval < 0) goto bad_fork_free_pid; pidfd = retval; + + pidfile = anon_inode_getfile("[pidfd]", &pidfd_fops, pid, + O_RDWR | O_CLOEXEC); + if (IS_ERR(pidfile)) { + put_unused_fd(pidfd); + goto bad_fork_free_pid; + } + get_pid(pid); /* held by pidfile now */ + retval = put_user(pidfd, parent_tidptr); if (retval) goto bad_fork_put_pidfd; @@ -2180,6 +2153,9 @@ static __latent_entropy struct task_struct *copy_process( goto bad_fork_cancel_cgroup; } + /* past the last point of failure */ + if (pidfile) + fd_install(pidfd, pidfile); init_task_pid_links(p); if (likely(p->pid)) { @@ -2246,8 +2222,10 @@ bad_fork_cancel_cgroup: bad_fork_cgroup_threadgroup_change_end: cgroup_threadgroup_change_end(current); bad_fork_put_pidfd: - if (clone_flags & CLONE_PIDFD) - ksys_close(pidfd); + if (clone_flags & CLONE_PIDFD) { + fput(pidfile); + put_unused_fd(pidfd); + } bad_fork_free_pid: if (pid != &init_struct_pid) free_pid(pid); diff --git a/samples/pidfd/pidfd-metadata.c b/samples/pidfd/pidfd-metadata.c index 14b454448429..c459155daf9a 100644 --- a/samples/pidfd/pidfd-metadata.c +++ b/samples/pidfd/pidfd-metadata.c @@ -83,7 +83,7 @@ static int pidfd_metadata_fd(pid_t pid, int pidfd) int main(int argc, char *argv[]) { - int pidfd = 0, ret = EXIT_FAILURE; + int pidfd = -1, ret = EXIT_FAILURE; char buf[4096] = { 0 }; pid_t pid; int procfd, statusfd; @@ -91,7 +91,11 @@ int main(int argc, char *argv[]) pid = pidfd_clone(CLONE_PIDFD, &pidfd); if (pid < 0) - exit(ret); + err(ret, "CLONE_PIDFD"); + if (pidfd == -1) { + warnx("CLONE_PIDFD is not supported by the kernel"); + goto out; + } procfd = pidfd_metadata_fd(pid, pidfd); close(pidfd); |