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![Kalesh Singh](/assets/img/avatar_default.png)
And 'ino' field to /proc/<pid>/fdinfo/<FD> and /proc/<pid>/task/<tid>/fdinfo/<FD>. The inode numbers can be used to uniquely identify DMA buffers in user space and avoids a dependency on /proc/<pid>/fd/* when accounting per-process DMA buffer sizes. Link: https://lkml.kernel.org/r/20210308170651.919148-2-kaleshsingh@google.com Signed-off-by: Kalesh Singh <kaleshsingh@google.com> Acked-by: Randy Dunlap <rdunlap@infradead.org> Acked-by: Christian König <christian.koenig@amd.com> Cc: Jann Horn <jannh@google.com> Cc: Jeff Vander Stoep <jeffv@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Hridya Valsaraju <hridya@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Kalesh Singh <kaleshsingh@google.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Alexey Gladkov <gladkov.alexey@gmail.com> Cc: Szabolcs Nagy <szabolcs.nagy@arm.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Christian Brauner <christian.brauner@ubuntu.com> Cc: Michel Lespinasse <walken@google.com> Cc: Bernd Edlinger <bernd.edlinger@hotmail.de> Cc: Andrei Vagin <avagin@gmail.com> Cc: Helge Deller <deller@gmx.de> Cc: James Morris <jamorris@linux.microsoft.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
360 lines
7.7 KiB
C
360 lines
7.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/sched/signal.h>
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#include <linux/errno.h>
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#include <linux/dcache.h>
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#include <linux/path.h>
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#include <linux/fdtable.h>
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#include <linux/namei.h>
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#include <linux/pid.h>
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#include <linux/ptrace.h>
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#include <linux/security.h>
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#include <linux/file.h>
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#include <linux/seq_file.h>
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#include <linux/fs.h>
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#include <linux/proc_fs.h>
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#include "../mount.h"
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#include "internal.h"
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#include "fd.h"
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static int seq_show(struct seq_file *m, void *v)
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{
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struct files_struct *files = NULL;
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int f_flags = 0, ret = -ENOENT;
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struct file *file = NULL;
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struct task_struct *task;
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task = get_proc_task(m->private);
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if (!task)
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return -ENOENT;
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task_lock(task);
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files = task->files;
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if (files) {
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unsigned int fd = proc_fd(m->private);
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spin_lock(&files->file_lock);
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file = files_lookup_fd_locked(files, fd);
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if (file) {
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struct fdtable *fdt = files_fdtable(files);
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f_flags = file->f_flags;
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if (close_on_exec(fd, fdt))
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f_flags |= O_CLOEXEC;
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get_file(file);
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ret = 0;
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}
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spin_unlock(&files->file_lock);
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}
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task_unlock(task);
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put_task_struct(task);
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if (ret)
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return ret;
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seq_printf(m, "pos:\t%lli\nflags:\t0%o\nmnt_id:\t%i\nino:\t%lu\n",
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(long long)file->f_pos, f_flags,
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real_mount(file->f_path.mnt)->mnt_id,
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file_inode(file)->i_ino);
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/* show_fd_locks() never deferences files so a stale value is safe */
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show_fd_locks(m, file, files);
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if (seq_has_overflowed(m))
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goto out;
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if (file->f_op->show_fdinfo)
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file->f_op->show_fdinfo(m, file);
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out:
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fput(file);
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return 0;
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}
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static int seq_fdinfo_open(struct inode *inode, struct file *file)
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{
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bool allowed = false;
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struct task_struct *task = get_proc_task(inode);
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if (!task)
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return -ESRCH;
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allowed = ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS);
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put_task_struct(task);
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if (!allowed)
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return -EACCES;
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return single_open(file, seq_show, inode);
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}
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static const struct file_operations proc_fdinfo_file_operations = {
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.open = seq_fdinfo_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = single_release,
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};
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static bool tid_fd_mode(struct task_struct *task, unsigned fd, fmode_t *mode)
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{
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struct file *file;
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rcu_read_lock();
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file = task_lookup_fd_rcu(task, fd);
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if (file)
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*mode = file->f_mode;
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rcu_read_unlock();
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return !!file;
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}
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static void tid_fd_update_inode(struct task_struct *task, struct inode *inode,
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fmode_t f_mode)
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{
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task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
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if (S_ISLNK(inode->i_mode)) {
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unsigned i_mode = S_IFLNK;
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if (f_mode & FMODE_READ)
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i_mode |= S_IRUSR | S_IXUSR;
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if (f_mode & FMODE_WRITE)
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i_mode |= S_IWUSR | S_IXUSR;
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inode->i_mode = i_mode;
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}
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security_task_to_inode(task, inode);
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}
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static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
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{
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struct task_struct *task;
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struct inode *inode;
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unsigned int fd;
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if (flags & LOOKUP_RCU)
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return -ECHILD;
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inode = d_inode(dentry);
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task = get_proc_task(inode);
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fd = proc_fd(inode);
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if (task) {
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fmode_t f_mode;
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if (tid_fd_mode(task, fd, &f_mode)) {
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tid_fd_update_inode(task, inode, f_mode);
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put_task_struct(task);
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return 1;
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}
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put_task_struct(task);
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}
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return 0;
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}
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static const struct dentry_operations tid_fd_dentry_operations = {
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.d_revalidate = tid_fd_revalidate,
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.d_delete = pid_delete_dentry,
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};
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static int proc_fd_link(struct dentry *dentry, struct path *path)
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{
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struct task_struct *task;
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int ret = -ENOENT;
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task = get_proc_task(d_inode(dentry));
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if (task) {
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unsigned int fd = proc_fd(d_inode(dentry));
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struct file *fd_file;
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fd_file = fget_task(task, fd);
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if (fd_file) {
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*path = fd_file->f_path;
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path_get(&fd_file->f_path);
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ret = 0;
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fput(fd_file);
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}
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put_task_struct(task);
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}
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return ret;
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}
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struct fd_data {
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fmode_t mode;
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unsigned fd;
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};
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static struct dentry *proc_fd_instantiate(struct dentry *dentry,
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struct task_struct *task, const void *ptr)
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{
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const struct fd_data *data = ptr;
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struct proc_inode *ei;
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struct inode *inode;
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inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK);
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if (!inode)
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return ERR_PTR(-ENOENT);
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ei = PROC_I(inode);
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ei->fd = data->fd;
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inode->i_op = &proc_pid_link_inode_operations;
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inode->i_size = 64;
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ei->op.proc_get_link = proc_fd_link;
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tid_fd_update_inode(task, inode, data->mode);
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d_set_d_op(dentry, &tid_fd_dentry_operations);
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return d_splice_alias(inode, dentry);
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}
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static struct dentry *proc_lookupfd_common(struct inode *dir,
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struct dentry *dentry,
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instantiate_t instantiate)
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{
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struct task_struct *task = get_proc_task(dir);
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struct fd_data data = {.fd = name_to_int(&dentry->d_name)};
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struct dentry *result = ERR_PTR(-ENOENT);
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if (!task)
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goto out_no_task;
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if (data.fd == ~0U)
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goto out;
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if (!tid_fd_mode(task, data.fd, &data.mode))
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goto out;
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result = instantiate(dentry, task, &data);
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out:
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put_task_struct(task);
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out_no_task:
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return result;
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}
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static int proc_readfd_common(struct file *file, struct dir_context *ctx,
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instantiate_t instantiate)
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{
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struct task_struct *p = get_proc_task(file_inode(file));
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unsigned int fd;
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if (!p)
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return -ENOENT;
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if (!dir_emit_dots(file, ctx))
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goto out;
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rcu_read_lock();
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for (fd = ctx->pos - 2;; fd++) {
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struct file *f;
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struct fd_data data;
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char name[10 + 1];
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unsigned int len;
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f = task_lookup_next_fd_rcu(p, &fd);
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ctx->pos = fd + 2LL;
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if (!f)
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break;
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data.mode = f->f_mode;
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rcu_read_unlock();
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data.fd = fd;
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len = snprintf(name, sizeof(name), "%u", fd);
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if (!proc_fill_cache(file, ctx,
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name, len, instantiate, p,
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&data))
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goto out;
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cond_resched();
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rcu_read_lock();
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}
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rcu_read_unlock();
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out:
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put_task_struct(p);
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return 0;
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}
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static int proc_readfd(struct file *file, struct dir_context *ctx)
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{
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return proc_readfd_common(file, ctx, proc_fd_instantiate);
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}
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const struct file_operations proc_fd_operations = {
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.read = generic_read_dir,
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.iterate_shared = proc_readfd,
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.llseek = generic_file_llseek,
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};
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static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
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unsigned int flags)
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{
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return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
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}
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/*
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* /proc/pid/fd needs a special permission handler so that a process can still
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* access /proc/self/fd after it has executed a setuid().
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*/
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int proc_fd_permission(struct user_namespace *mnt_userns,
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struct inode *inode, int mask)
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{
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struct task_struct *p;
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int rv;
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rv = generic_permission(&init_user_ns, inode, mask);
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if (rv == 0)
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return rv;
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rcu_read_lock();
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p = pid_task(proc_pid(inode), PIDTYPE_PID);
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if (p && same_thread_group(p, current))
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rv = 0;
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rcu_read_unlock();
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return rv;
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}
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const struct inode_operations proc_fd_inode_operations = {
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.lookup = proc_lookupfd,
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.permission = proc_fd_permission,
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.setattr = proc_setattr,
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};
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static struct dentry *proc_fdinfo_instantiate(struct dentry *dentry,
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struct task_struct *task, const void *ptr)
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{
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const struct fd_data *data = ptr;
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struct proc_inode *ei;
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struct inode *inode;
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inode = proc_pid_make_inode(dentry->d_sb, task, S_IFREG | S_IRUGO);
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if (!inode)
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return ERR_PTR(-ENOENT);
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ei = PROC_I(inode);
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ei->fd = data->fd;
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inode->i_fop = &proc_fdinfo_file_operations;
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tid_fd_update_inode(task, inode, 0);
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d_set_d_op(dentry, &tid_fd_dentry_operations);
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return d_splice_alias(inode, dentry);
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}
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static struct dentry *
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proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags)
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{
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return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
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}
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static int proc_readfdinfo(struct file *file, struct dir_context *ctx)
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{
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return proc_readfd_common(file, ctx,
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proc_fdinfo_instantiate);
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}
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const struct inode_operations proc_fdinfo_inode_operations = {
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.lookup = proc_lookupfdinfo,
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.setattr = proc_setattr,
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};
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const struct file_operations proc_fdinfo_operations = {
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.read = generic_read_dir,
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.iterate_shared = proc_readfdinfo,
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.llseek = generic_file_llseek,
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};
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