1 // SPDX-License-Identifier: GPL-2.0 2 /* 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 from 6 * the rest of fs/proc, but has rather close relationships with 7 * fs/namespace.c, thus here instead of fs/proc 8 * 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 21 static __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 40 struct proc_fs_opts { 41 int flag; 42 const char *str; 43 }; 44 45 static 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 64 static void show_mnt_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 87 static inline void mangle(struct seq_file *m, const char *s) 88 { 89 seq_escape(m, s, " \t\n\\"); 90 } 91 92 static 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 } 100 101 static 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_mnt_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"); 131 out: 132 return err; 133 } 134 135 static 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 if (sb->s_op->show_path) { 146 err = sb->s_op->show_path(m, mnt->mnt_root); 147 if (err) 148 goto out; 149 } else { 150 seq_dentry(m, mnt->mnt_root, " \t\n\\"); 151 } 152 seq_putc(m, ' '); 153 154 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */ 155 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\"); 156 if (err) 157 goto out; 158 159 seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw"); 160 show_mnt_opts(m, mnt); 161 162 /* Tagged fields ("foo:X" or "bar") */ 163 if (IS_MNT_SHARED(r)) 164 seq_printf(m, " shared:%i", r->mnt_group_id); 165 if (IS_MNT_SLAVE(r)) { 166 int master = r->mnt_master->mnt_group_id; 167 int dom = get_dominating_id(r, &p->root); 168 seq_printf(m, " master:%i", master); 169 if (dom && dom != master) 170 seq_printf(m, " propagate_from:%i", dom); 171 } 172 if (IS_MNT_UNBINDABLE(r)) 173 seq_puts(m, " unbindable"); 174 175 /* Filesystem specific data */ 176 seq_puts(m, " - "); 177 show_type(m, sb); 178 seq_putc(m, ' '); 179 if (sb->s_op->show_devname) { 180 err = sb->s_op->show_devname(m, mnt->mnt_root); 181 if (err) 182 goto out; 183 } else { 184 mangle(m, r->mnt_devname ? r->mnt_devname : "none"); 185 } 186 seq_puts(m, sb_rdonly(sb) ? " ro" : " rw"); 187 err = show_sb_opts(m, sb); 188 if (err) 189 goto out; 190 if (sb->s_op->show_options) 191 err = sb->s_op->show_options(m, mnt->mnt_root); 192 seq_putc(m, '\n'); 193 out: 194 return err; 195 } 196 197 static int show_vfsstat(struct seq_file *m, struct vfsmount *mnt) 198 { 199 struct proc_mounts *p = m->private; 200 struct mount *r = real_mount(mnt); 201 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; 202 struct super_block *sb = mnt_path.dentry->d_sb; 203 int err; 204 205 /* device */ 206 if (sb->s_op->show_devname) { 207 seq_puts(m, "device "); 208 err = sb->s_op->show_devname(m, mnt_path.dentry); 209 if (err) 210 goto out; 211 } else { 212 if (r->mnt_devname) { 213 seq_puts(m, "device "); 214 mangle(m, r->mnt_devname); 215 } else 216 seq_puts(m, "no device"); 217 } 218 219 /* mount point */ 220 seq_puts(m, " mounted on "); 221 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */ 222 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\"); 223 if (err) 224 goto out; 225 seq_putc(m, ' '); 226 227 /* file system type */ 228 seq_puts(m, "with fstype "); 229 show_type(m, sb); 230 231 /* optional statistics */ 232 if (sb->s_op->show_stats) { 233 seq_putc(m, ' '); 234 err = sb->s_op->show_stats(m, mnt_path.dentry); 235 } 236 237 seq_putc(m, '\n'); 238 out: 239 return err; 240 } 241 242 static int mounts_open_common(struct inode *inode, struct file *file, 243 int (*show)(struct seq_file *, struct vfsmount *)) 244 { 245 struct task_struct *task = get_proc_task(inode); 246 struct nsproxy *nsp; 247 struct mnt_namespace *ns = NULL; 248 struct path root; 249 struct proc_mounts *p; 250 struct seq_file *m; 251 int ret = -EINVAL; 252 253 if (!task) 254 goto err; 255 256 task_lock(task); 257 nsp = task->nsproxy; 258 if (!nsp || !nsp->mnt_ns) { 259 task_unlock(task); 260 put_task_struct(task); 261 goto err; 262 } 263 ns = nsp->mnt_ns; 264 get_mnt_ns(ns); 265 if (!task->fs) { 266 task_unlock(task); 267 put_task_struct(task); 268 ret = -ENOENT; 269 goto err_put_ns; 270 } 271 get_fs_root(task->fs, &root); 272 task_unlock(task); 273 put_task_struct(task); 274 275 ret = seq_open_private(file, &mounts_op, sizeof(struct proc_mounts)); 276 if (ret) 277 goto err_put_path; 278 279 m = file->private_data; 280 m->poll_event = ns->event; 281 282 p = m->private; 283 p->ns = ns; 284 p->root = root; 285 p->show = show; 286 INIT_LIST_HEAD(&p->cursor.mnt_list); 287 p->cursor.mnt.mnt_flags = MNT_CURSOR; 288 289 return 0; 290 291 err_put_path: 292 path_put(&root); 293 err_put_ns: 294 put_mnt_ns(ns); 295 err: 296 return ret; 297 } 298 299 static int mounts_release(struct inode *inode, struct file *file) 300 { 301 struct seq_file *m = file->private_data; 302 struct proc_mounts *p = m->private; 303 path_put(&p->root); 304 mnt_cursor_del(p->ns, &p->cursor); 305 put_mnt_ns(p->ns); 306 return seq_release_private(inode, file); 307 } 308 309 static int mounts_open(struct inode *inode, struct file *file) 310 { 311 return mounts_open_common(inode, file, show_vfsmnt); 312 } 313 314 static int mountinfo_open(struct inode *inode, struct file *file) 315 { 316 return mounts_open_common(inode, file, show_mountinfo); 317 } 318 319 static int mountstats_open(struct inode *inode, struct file *file) 320 { 321 return mounts_open_common(inode, file, show_vfsstat); 322 } 323 324 const struct file_operations proc_mounts_operations = { 325 .open = mounts_open, 326 .read_iter = seq_read_iter, 327 .splice_read = generic_file_splice_read, 328 .llseek = seq_lseek, 329 .release = mounts_release, 330 .poll = mounts_poll, 331 }; 332 333 const struct file_operations proc_mountinfo_operations = { 334 .open = mountinfo_open, 335 .read_iter = seq_read_iter, 336 .splice_read = generic_file_splice_read, 337 .llseek = seq_lseek, 338 .release = mounts_release, 339 .poll = mounts_poll, 340 }; 341 342 const struct file_operations proc_mountstats_operations = { 343 .open = mountstats_open, 344 .read_iter = seq_read_iter, 345 .splice_read = generic_file_splice_read, 346 .llseek = seq_lseek, 347 .release = mounts_release, 348 }; 349