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9ff7258575
Pull proc updates from Eric Biederman: "This has four sets of changes: - modernize proc to support multiple private instances - ensure we see the exit of each process tid exactly - remove has_group_leader_pid - use pids not tasks in posix-cpu-timers lookup Alexey updated proc so each mount of proc uses a new superblock. This allows people to actually use mount options with proc with no fear of messing up another mount of proc. Given the kernel's internal mounts of proc for things like uml this was a real problem, and resulted in Android's hidepid mount options being ignored and introducing security issues. The rest of the changes are small cleanups and fixes that came out of my work to allow this change to proc. In essence it is swapping the pids in de_thread during exec which removes a special case the code had to handle. Then updating the code to stop handling that special case" * 'proc-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: proc: proc_pid_ns takes super_block as an argument remove the no longer needed pid_alive() check in __task_pid_nr_ns() posix-cpu-timers: Replace __get_task_for_clock with pid_for_clock posix-cpu-timers: Replace cpu_timer_pid_type with clock_pid_type posix-cpu-timers: Extend rcu_read_lock removing task_struct references signal: Remove has_group_leader_pid exec: Remove BUG_ON(has_group_leader_pid) posix-cpu-timer: Unify the now redundant code in lookup_task posix-cpu-timer: Tidy up group_leader logic in lookup_task proc: Ensure we see the exit of each process tid exactly once rculist: Add hlists_swap_heads_rcu proc: Use PIDTYPE_TGID in next_tgid Use proc_pid_ns() to get pid_namespace from the proc superblock proc: use named enums for better readability proc: use human-readable values for hidepid docs: proc: add documentation for "hidepid=4" and "subset=pid" options and new mount behavior proc: add option to mount only a pids subset proc: instantiate only pids that we can ptrace on 'hidepid=4' mount option proc: allow to mount many instances of proc in one pid namespace proc: rename struct proc_fs_info to proc_fs_opts
342 lines
7.9 KiB
C
342 lines
7.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* fs/proc_namespace.c - handling of /proc/<pid>/{mounts,mountinfo,mountstats}
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*
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* In fact, that's a piece of procfs; it's *almost* isolated from
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* the rest of fs/proc, but has rather close relationships with
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* fs/namespace.c, thus here instead of fs/proc
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*
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*/
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#include <linux/mnt_namespace.h>
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#include <linux/nsproxy.h>
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#include <linux/security.h>
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#include <linux/fs_struct.h>
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#include <linux/sched/task.h>
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#include "proc/internal.h" /* only for get_proc_task() in ->open() */
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#include "pnode.h"
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#include "internal.h"
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static __poll_t mounts_poll(struct file *file, poll_table *wait)
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{
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struct seq_file *m = file->private_data;
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struct proc_mounts *p = m->private;
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struct mnt_namespace *ns = p->ns;
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__poll_t res = EPOLLIN | EPOLLRDNORM;
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int event;
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poll_wait(file, &p->ns->poll, wait);
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event = READ_ONCE(ns->event);
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if (m->poll_event != event) {
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m->poll_event = event;
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res |= EPOLLERR | EPOLLPRI;
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}
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return res;
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}
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struct proc_fs_opts {
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int flag;
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const char *str;
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};
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static int show_sb_opts(struct seq_file *m, struct super_block *sb)
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{
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static const struct proc_fs_opts fs_opts[] = {
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{ SB_SYNCHRONOUS, ",sync" },
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{ SB_DIRSYNC, ",dirsync" },
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{ SB_MANDLOCK, ",mand" },
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{ SB_LAZYTIME, ",lazytime" },
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{ 0, NULL }
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};
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const struct proc_fs_opts *fs_infop;
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for (fs_infop = fs_opts; fs_infop->flag; fs_infop++) {
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if (sb->s_flags & fs_infop->flag)
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seq_puts(m, fs_infop->str);
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}
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return security_sb_show_options(m, sb);
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}
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static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt)
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{
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static const struct proc_fs_opts mnt_opts[] = {
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{ MNT_NOSUID, ",nosuid" },
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{ MNT_NODEV, ",nodev" },
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{ MNT_NOEXEC, ",noexec" },
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{ MNT_NOATIME, ",noatime" },
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{ MNT_NODIRATIME, ",nodiratime" },
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{ MNT_RELATIME, ",relatime" },
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{ 0, NULL }
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};
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const struct proc_fs_opts *fs_infop;
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for (fs_infop = mnt_opts; fs_infop->flag; fs_infop++) {
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if (mnt->mnt_flags & fs_infop->flag)
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seq_puts(m, fs_infop->str);
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}
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}
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static inline void mangle(struct seq_file *m, const char *s)
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{
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seq_escape(m, s, " \t\n\\");
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}
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static void show_type(struct seq_file *m, struct super_block *sb)
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{
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mangle(m, sb->s_type->name);
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if (sb->s_subtype) {
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seq_putc(m, '.');
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mangle(m, sb->s_subtype);
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}
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}
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static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt)
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{
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struct proc_mounts *p = m->private;
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struct mount *r = real_mount(mnt);
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struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
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struct super_block *sb = mnt_path.dentry->d_sb;
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int err;
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if (sb->s_op->show_devname) {
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err = sb->s_op->show_devname(m, mnt_path.dentry);
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if (err)
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goto out;
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} else {
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mangle(m, r->mnt_devname ? r->mnt_devname : "none");
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}
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seq_putc(m, ' ');
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/* mountpoints outside of chroot jail will give SEQ_SKIP on this */
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err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
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if (err)
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goto out;
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seq_putc(m, ' ');
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show_type(m, sb);
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seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
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err = show_sb_opts(m, sb);
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if (err)
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goto out;
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show_mnt_opts(m, mnt);
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if (sb->s_op->show_options)
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err = sb->s_op->show_options(m, mnt_path.dentry);
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seq_puts(m, " 0 0\n");
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out:
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return err;
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}
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static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt)
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{
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struct proc_mounts *p = m->private;
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struct mount *r = real_mount(mnt);
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struct super_block *sb = mnt->mnt_sb;
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struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
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int err;
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seq_printf(m, "%i %i %u:%u ", r->mnt_id, r->mnt_parent->mnt_id,
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MAJOR(sb->s_dev), MINOR(sb->s_dev));
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if (sb->s_op->show_path) {
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err = sb->s_op->show_path(m, mnt->mnt_root);
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if (err)
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goto out;
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} else {
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seq_dentry(m, mnt->mnt_root, " \t\n\\");
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}
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seq_putc(m, ' ');
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/* mountpoints outside of chroot jail will give SEQ_SKIP on this */
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err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
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if (err)
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goto out;
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seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
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show_mnt_opts(m, mnt);
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/* Tagged fields ("foo:X" or "bar") */
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if (IS_MNT_SHARED(r))
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seq_printf(m, " shared:%i", r->mnt_group_id);
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if (IS_MNT_SLAVE(r)) {
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int master = r->mnt_master->mnt_group_id;
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int dom = get_dominating_id(r, &p->root);
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seq_printf(m, " master:%i", master);
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if (dom && dom != master)
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seq_printf(m, " propagate_from:%i", dom);
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}
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if (IS_MNT_UNBINDABLE(r))
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seq_puts(m, " unbindable");
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/* Filesystem specific data */
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seq_puts(m, " - ");
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show_type(m, sb);
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seq_putc(m, ' ');
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if (sb->s_op->show_devname) {
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err = sb->s_op->show_devname(m, mnt->mnt_root);
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if (err)
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goto out;
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} else {
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mangle(m, r->mnt_devname ? r->mnt_devname : "none");
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}
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seq_puts(m, sb_rdonly(sb) ? " ro" : " rw");
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err = show_sb_opts(m, sb);
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if (err)
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goto out;
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if (sb->s_op->show_options)
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err = sb->s_op->show_options(m, mnt->mnt_root);
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seq_putc(m, '\n');
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out:
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return err;
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}
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static int show_vfsstat(struct seq_file *m, struct vfsmount *mnt)
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{
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struct proc_mounts *p = m->private;
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struct mount *r = real_mount(mnt);
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struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
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struct super_block *sb = mnt_path.dentry->d_sb;
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int err;
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/* device */
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if (sb->s_op->show_devname) {
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seq_puts(m, "device ");
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err = sb->s_op->show_devname(m, mnt_path.dentry);
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if (err)
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goto out;
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} else {
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if (r->mnt_devname) {
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seq_puts(m, "device ");
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mangle(m, r->mnt_devname);
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} else
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seq_puts(m, "no device");
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}
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/* mount point */
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seq_puts(m, " mounted on ");
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/* mountpoints outside of chroot jail will give SEQ_SKIP on this */
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err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
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if (err)
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goto out;
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seq_putc(m, ' ');
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/* file system type */
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seq_puts(m, "with fstype ");
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show_type(m, sb);
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/* optional statistics */
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if (sb->s_op->show_stats) {
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seq_putc(m, ' ');
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err = sb->s_op->show_stats(m, mnt_path.dentry);
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}
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seq_putc(m, '\n');
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out:
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return err;
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}
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static int mounts_open_common(struct inode *inode, struct file *file,
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int (*show)(struct seq_file *, struct vfsmount *))
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{
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struct task_struct *task = get_proc_task(inode);
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struct nsproxy *nsp;
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struct mnt_namespace *ns = NULL;
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struct path root;
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struct proc_mounts *p;
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struct seq_file *m;
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int ret = -EINVAL;
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if (!task)
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goto err;
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task_lock(task);
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nsp = task->nsproxy;
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if (!nsp || !nsp->mnt_ns) {
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task_unlock(task);
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put_task_struct(task);
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goto err;
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}
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ns = nsp->mnt_ns;
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get_mnt_ns(ns);
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if (!task->fs) {
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task_unlock(task);
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put_task_struct(task);
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ret = -ENOENT;
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goto err_put_ns;
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}
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get_fs_root(task->fs, &root);
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task_unlock(task);
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put_task_struct(task);
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ret = seq_open_private(file, &mounts_op, sizeof(struct proc_mounts));
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if (ret)
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goto err_put_path;
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m = file->private_data;
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m->poll_event = ns->event;
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p = m->private;
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p->ns = ns;
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p->root = root;
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p->show = show;
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INIT_LIST_HEAD(&p->cursor.mnt_list);
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p->cursor.mnt.mnt_flags = MNT_CURSOR;
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return 0;
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err_put_path:
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path_put(&root);
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err_put_ns:
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put_mnt_ns(ns);
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err:
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return ret;
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}
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static int mounts_release(struct inode *inode, struct file *file)
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{
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struct seq_file *m = file->private_data;
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struct proc_mounts *p = m->private;
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path_put(&p->root);
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mnt_cursor_del(p->ns, &p->cursor);
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put_mnt_ns(p->ns);
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return seq_release_private(inode, file);
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}
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static int mounts_open(struct inode *inode, struct file *file)
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{
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return mounts_open_common(inode, file, show_vfsmnt);
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}
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static int mountinfo_open(struct inode *inode, struct file *file)
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{
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return mounts_open_common(inode, file, show_mountinfo);
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}
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static int mountstats_open(struct inode *inode, struct file *file)
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{
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return mounts_open_common(inode, file, show_vfsstat);
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}
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const struct file_operations proc_mounts_operations = {
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.open = mounts_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = mounts_release,
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.poll = mounts_poll,
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};
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const struct file_operations proc_mountinfo_operations = {
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.open = mountinfo_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = mounts_release,
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.poll = mounts_poll,
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};
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const struct file_operations proc_mountstats_operations = {
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.open = mountstats_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = mounts_release,
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};
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