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 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_mnt_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'); 189 out: 190 return err; 191 } 192 193 static 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 } else 212 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'); 234 out: 235 return err; 236 } 237 238 static 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 } 292 293 static 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 } 301 302 static int mounts_open(struct inode *inode, struct file *file) 303 { 304 return mounts_open_common(inode, file, show_vfsmnt); 305 } 306 307 static int mountinfo_open(struct inode *inode, struct file *file) 308 { 309 return mounts_open_common(inode, file, show_mountinfo); 310 } 311 312 static int mountstats_open(struct inode *inode, struct file *file) 313 { 314 return mounts_open_common(inode, file, show_vfsstat); 315 } 316 317 const 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 }; 325 326 const 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 }; 334 335 const 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