342 lines · c
1// SPDX-License-Identifier: GPL-2.02/*3 * fs/proc_namespace.c - handling of /proc/<pid>/{mounts,mountinfo,mountstats}4 *5 * In fact, that's a piece of procfs; it's *almost* isolated from6 * the rest of fs/proc, but has rather close relationships with7 * fs/namespace.c, thus here instead of fs/proc8 *9 */10#include <linux/mnt_namespace.h>11#include <linux/nsproxy.h>12#include <linux/security.h>13#include <linux/fs_struct.h>14#include <linux/sched/task.h>15 16#include "proc/internal.h" /* only for get_proc_task() in ->open() */17 18#include "pnode.h"19#include "internal.h"20 21static __poll_t mounts_poll(struct file *file, poll_table *wait)22{23 struct seq_file *m = file->private_data;24 struct proc_mounts *p = m->private;25 struct mnt_namespace *ns = p->ns;26 __poll_t res = EPOLLIN | EPOLLRDNORM;27 int event;28 29 poll_wait(file, &p->ns->poll, wait);30 31 event = READ_ONCE(ns->event);32 if (m->poll_event != event) {33 m->poll_event = event;34 res |= EPOLLERR | EPOLLPRI;35 }36 37 return res;38}39 40struct proc_fs_opts {41 int flag;42 const char *str;43};44 45static int show_sb_opts(struct seq_file *m, struct super_block *sb)46{47 static const struct proc_fs_opts fs_opts[] = {48 { SB_SYNCHRONOUS, ",sync" },49 { SB_DIRSYNC, ",dirsync" },50 { SB_MANDLOCK, ",mand" },51 { SB_LAZYTIME, ",lazytime" },52 { 0, NULL }53 };54 const struct proc_fs_opts *fs_infop;55 56 for (fs_infop = fs_opts; fs_infop->flag; fs_infop++) {57 if (sb->s_flags & fs_infop->flag)58 seq_puts(m, fs_infop->str);59 }60 61 return security_sb_show_options(m, sb);62}63 64static void show_vfsmnt_opts(struct seq_file *m, struct vfsmount *mnt)65{66 static const struct proc_fs_opts mnt_opts[] = {67 { MNT_NOSUID, ",nosuid" },68 { MNT_NODEV, ",nodev" },69 { MNT_NOEXEC, ",noexec" },70 { MNT_NOATIME, ",noatime" },71 { MNT_NODIRATIME, ",nodiratime" },72 { MNT_RELATIME, ",relatime" },73 { MNT_NOSYMFOLLOW, ",nosymfollow" },74 { 0, NULL }75 };76 const struct proc_fs_opts *fs_infop;77 78 for (fs_infop = mnt_opts; fs_infop->flag; fs_infop++) {79 if (mnt->mnt_flags & fs_infop->flag)80 seq_puts(m, fs_infop->str);81 }82 83 if (is_idmapped_mnt(mnt))84 seq_puts(m, ",idmapped");85}86 87static inline void mangle(struct seq_file *m, const char *s)88{89 seq_escape(m, s, " \t\n\\#");90}91 92static void show_type(struct seq_file *m, struct super_block *sb)93{94 mangle(m, sb->s_type->name);95 if (sb->s_subtype) {96 seq_putc(m, '.');97 mangle(m, sb->s_subtype);98 }99}100 101static HWJS_SUSPENDS int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt)102{103 struct proc_mounts *p = m->private;104 struct mount *r = real_mount(mnt);105 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };106 struct super_block *sb = mnt_path.dentry->d_sb;107 int err;108 109 if (sb->s_op->show_devname) {110 err = sb->s_op->show_devname(m, mnt_path.dentry);111 if (err)112 goto out;113 } else {114 mangle(m, r->mnt_devname ? r->mnt_devname : "none");115 }116 seq_putc(m, ' ');117 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */118 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");119 if (err)120 goto out;121 seq_putc(m, ' ');122 show_type(m, sb);123 seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");124 err = show_sb_opts(m, sb);125 if (err)126 goto out;127 show_vfsmnt_opts(m, mnt);128 if (sb->s_op->show_options)129 err = sb->s_op->show_options(m, mnt_path.dentry);130 seq_puts(m, " 0 0\n");131out:132 return err;133}134 135static HWJS_SUSPENDS int show_mountinfo(struct seq_file *m, struct vfsmount *mnt)136{137 struct proc_mounts *p = m->private;138 struct mount *r = real_mount(mnt);139 struct super_block *sb = mnt->mnt_sb;140 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };141 int err;142 143 seq_printf(m, "%i %i %u:%u ", r->mnt_id, r->mnt_parent->mnt_id,144 MAJOR(sb->s_dev), MINOR(sb->s_dev));145 err = show_path(m, mnt->mnt_root);146 if (err)147 goto out;148 seq_putc(m, ' ');149 150 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */151 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");152 if (err)153 goto out;154 155 seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");156 show_vfsmnt_opts(m, mnt);157 158 /* Tagged fields ("foo:X" or "bar") */159 if (IS_MNT_SHARED(r))160 seq_printf(m, " shared:%i", r->mnt_group_id);161 if (IS_MNT_SLAVE(r)) {162 int master = r->mnt_master->mnt_group_id;163 int dom = get_dominating_id(r, &p->root);164 seq_printf(m, " master:%i", master);165 if (dom && dom != master)166 seq_printf(m, " propagate_from:%i", dom);167 }168 if (IS_MNT_UNBINDABLE(r))169 seq_puts(m, " unbindable");170 171 /* Filesystem specific data */172 seq_puts(m, " - ");173 show_type(m, sb);174 seq_putc(m, ' ');175 if (sb->s_op->show_devname) {176 err = sb->s_op->show_devname(m, mnt->mnt_root);177 if (err)178 goto out;179 } else {180 mangle(m, r->mnt_devname ? r->mnt_devname : "none");181 }182 seq_puts(m, sb_rdonly(sb) ? " ro" : " rw");183 err = show_sb_opts(m, sb);184 if (err)185 goto out;186 if (sb->s_op->show_options)187 err = sb->s_op->show_options(m, mnt->mnt_root);188 seq_putc(m, '\n');189out:190 return err;191}192 193static HWJS_SUSPENDS int show_vfsstat(struct seq_file *m, struct vfsmount *mnt)194{195 struct proc_mounts *p = m->private;196 struct mount *r = real_mount(mnt);197 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };198 struct super_block *sb = mnt_path.dentry->d_sb;199 int err;200 201 /* device */202 if (sb->s_op->show_devname) {203 seq_puts(m, "device ");204 err = sb->s_op->show_devname(m, mnt_path.dentry);205 if (err)206 goto out;207 } else {208 if (r->mnt_devname) {209 seq_puts(m, "device ");210 mangle(m, r->mnt_devname);211 } else212 seq_puts(m, "no device");213 }214 215 /* mount point */216 seq_puts(m, " mounted on ");217 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */218 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");219 if (err)220 goto out;221 seq_putc(m, ' ');222 223 /* file system type */224 seq_puts(m, "with fstype ");225 show_type(m, sb);226 227 /* optional statistics */228 if (sb->s_op->show_stats) {229 seq_putc(m, ' ');230 err = sb->s_op->show_stats(m, mnt_path.dentry);231 }232 233 seq_putc(m, '\n');234out:235 return err;236}237 238static HWJS_SUSPENDS int mounts_open_common(struct inode *inode, struct file *file,239 int (*show)(struct seq_file *, struct vfsmount *))240{241 struct task_struct *task = get_proc_task(inode);242 struct nsproxy *nsp;243 struct mnt_namespace *ns = NULL;244 struct path root;245 struct proc_mounts *p;246 struct seq_file *m;247 int ret = -EINVAL;248 249 if (!task)250 goto err;251 252 task_lock(task);253 nsp = task->nsproxy;254 if (!nsp || !nsp->mnt_ns) {255 task_unlock(task);256 put_task_struct(task);257 goto err;258 }259 ns = nsp->mnt_ns;260 get_mnt_ns(ns);261 if (!task->fs) {262 task_unlock(task);263 put_task_struct(task);264 ret = -ENOENT;265 goto err_put_ns;266 }267 get_fs_root(task->fs, &root);268 task_unlock(task);269 put_task_struct(task);270 271 ret = seq_open_private(file, &mounts_op, sizeof(struct proc_mounts));272 if (ret)273 goto err_put_path;274 275 m = file->private_data;276 m->poll_event = ns->event;277 278 p = m->private;279 p->ns = ns;280 p->root = root;281 p->show = show;282 283 return 0;284 285 err_put_path:286 path_put(&root);287 err_put_ns:288 put_mnt_ns(ns);289 err:290 return ret;291}292 293static HWJS_SUSPENDS int mounts_release(struct inode *inode, struct file *file)294{295 struct seq_file *m = file->private_data;296 struct proc_mounts *p = m->private;297 path_put(&p->root);298 put_mnt_ns(p->ns);299 return seq_release_private(inode, file);300}301 302static HWJS_SUSPENDS int mounts_open(struct inode *inode, struct file *file)303{304 return mounts_open_common(inode, file, show_vfsmnt);305}306 307static HWJS_SUSPENDS int mountinfo_open(struct inode *inode, struct file *file)308{309 return mounts_open_common(inode, file, show_mountinfo);310}311 312static HWJS_SUSPENDS int mountstats_open(struct inode *inode, struct file *file)313{314 return mounts_open_common(inode, file, show_vfsstat);315}316 317const struct file_operations proc_mounts_operations = {318 .open = mounts_open,319 .read_iter = seq_read_iter,320 .splice_read = copy_splice_read,321 .llseek = seq_lseek,322 .release = mounts_release,323 .poll = mounts_poll,324};325 326const struct file_operations proc_mountinfo_operations = {327 .open = mountinfo_open,328 .read_iter = seq_read_iter,329 .splice_read = copy_splice_read,330 .llseek = seq_lseek,331 .release = mounts_release,332 .poll = mounts_poll,333};334 335const struct file_operations proc_mountstats_operations = {336 .open = mountstats_open,337 .read_iter = seq_read_iter,338 .splice_read = copy_splice_read,339 .llseek = seq_lseek,340 .release = mounts_release,341};342