1 /* 2 * fs/proc_namespace.c - handling of /proc/<pid>/{mounts,mountinfo,mountstats} 3 * 4 * In fact, that's a piece of procfs; it's *almost* isolated from 5 * the rest of fs/proc, but has rather close relationships with 6 * fs/namespace.c, thus here instead of fs/proc 7 * 8 */ 9 #include <linux/mnt_namespace.h> 10 #include <linux/nsproxy.h> 11 #include <linux/security.h> 12 #include <linux/fs_struct.h> 13 #include "proc/internal.h" /* only for get_proc_task() in ->open() */ 14 15 #include "pnode.h" 16 #include "internal.h" 17 18 static unsigned mounts_poll(struct file *file, poll_table *wait) 19 { 20 struct seq_file *m = file->private_data; 21 struct proc_mounts *p = m->private; 22 struct mnt_namespace *ns = p->ns; 23 unsigned res = POLLIN | POLLRDNORM; 24 int event; 25 26 poll_wait(file, &p->ns->poll, wait); 27 28 event = ACCESS_ONCE(ns->event); 29 if (m->poll_event != event) { 30 m->poll_event = event; 31 res |= POLLERR | POLLPRI; 32 } 33 34 return res; 35 } 36 37 struct proc_fs_info { 38 int flag; 39 const char *str; 40 }; 41 42 static int show_sb_opts(struct seq_file *m, struct super_block *sb) 43 { 44 static const struct proc_fs_info fs_info[] = { 45 { MS_SYNCHRONOUS, ",sync" }, 46 { MS_DIRSYNC, ",dirsync" }, 47 { MS_MANDLOCK, ",mand" }, 48 { MS_LAZYTIME, ",lazytime" }, 49 { 0, NULL } 50 }; 51 const struct proc_fs_info *fs_infop; 52 53 for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { 54 if (sb->s_flags & fs_infop->flag) 55 seq_puts(m, fs_infop->str); 56 } 57 58 return security_sb_show_options(m, sb); 59 } 60 61 static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt) 62 { 63 static const struct proc_fs_info mnt_info[] = { 64 { MNT_NOSUID, ",nosuid" }, 65 { MNT_NODEV, ",nodev" }, 66 { MNT_NOEXEC, ",noexec" }, 67 { MNT_NOATIME, ",noatime" }, 68 { MNT_NODIRATIME, ",nodiratime" }, 69 { MNT_RELATIME, ",relatime" }, 70 { 0, NULL } 71 }; 72 const struct proc_fs_info *fs_infop; 73 74 for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { 75 if (mnt->mnt_flags & fs_infop->flag) 76 seq_puts(m, fs_infop->str); 77 } 78 } 79 80 static inline void mangle(struct seq_file *m, const char *s) 81 { 82 seq_escape(m, s, " \t\n\\"); 83 } 84 85 static void show_type(struct seq_file *m, struct super_block *sb) 86 { 87 mangle(m, sb->s_type->name); 88 if (sb->s_subtype && sb->s_subtype[0]) { 89 seq_putc(m, '.'); 90 mangle(m, sb->s_subtype); 91 } 92 } 93 94 static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt) 95 { 96 struct proc_mounts *p = m->private; 97 struct mount *r = real_mount(mnt); 98 int err = 0; 99 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; 100 struct super_block *sb = mnt_path.dentry->d_sb; 101 102 if (sb->s_op->show_devname) { 103 err = sb->s_op->show_devname(m, mnt_path.dentry); 104 if (err) 105 goto out; 106 } else { 107 mangle(m, r->mnt_devname ? r->mnt_devname : "none"); 108 } 109 seq_putc(m, ' '); 110 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */ 111 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\"); 112 if (err) 113 goto out; 114 seq_putc(m, ' '); 115 show_type(m, sb); 116 seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw"); 117 err = show_sb_opts(m, sb); 118 if (err) 119 goto out; 120 show_mnt_opts(m, mnt); 121 if (sb->s_op->show_options) 122 err = sb->s_op->show_options(m, mnt_path.dentry); 123 seq_puts(m, " 0 0\n"); 124 out: 125 return err; 126 } 127 128 static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt) 129 { 130 struct proc_mounts *p = m->private; 131 struct mount *r = real_mount(mnt); 132 struct super_block *sb = mnt->mnt_sb; 133 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; 134 int err = 0; 135 136 seq_printf(m, "%i %i %u:%u ", r->mnt_id, r->mnt_parent->mnt_id, 137 MAJOR(sb->s_dev), MINOR(sb->s_dev)); 138 if (sb->s_op->show_path) 139 err = sb->s_op->show_path(m, mnt->mnt_root); 140 else 141 seq_dentry(m, mnt->mnt_root, " \t\n\\"); 142 if (err) 143 goto out; 144 seq_putc(m, ' '); 145 146 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */ 147 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\"); 148 if (err) 149 goto out; 150 151 seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw"); 152 show_mnt_opts(m, mnt); 153 154 /* Tagged fields ("foo:X" or "bar") */ 155 if (IS_MNT_SHARED(r)) 156 seq_printf(m, " shared:%i", r->mnt_group_id); 157 if (IS_MNT_SLAVE(r)) { 158 int master = r->mnt_master->mnt_group_id; 159 int dom = get_dominating_id(r, &p->root); 160 seq_printf(m, " master:%i", master); 161 if (dom && dom != master) 162 seq_printf(m, " propagate_from:%i", dom); 163 } 164 if (IS_MNT_UNBINDABLE(r)) 165 seq_puts(m, " unbindable"); 166 167 /* Filesystem specific data */ 168 seq_puts(m, " - "); 169 show_type(m, sb); 170 seq_putc(m, ' '); 171 if (sb->s_op->show_devname) 172 err = sb->s_op->show_devname(m, mnt->mnt_root); 173 else 174 mangle(m, r->mnt_devname ? r->mnt_devname : "none"); 175 if (err) 176 goto out; 177 seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw"); 178 err = show_sb_opts(m, sb); 179 if (err) 180 goto out; 181 if (sb->s_op->show_options) 182 err = sb->s_op->show_options(m, mnt->mnt_root); 183 seq_putc(m, '\n'); 184 out: 185 return err; 186 } 187 188 static int show_vfsstat(struct seq_file *m, struct vfsmount *mnt) 189 { 190 struct proc_mounts *p = m->private; 191 struct mount *r = real_mount(mnt); 192 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; 193 struct super_block *sb = mnt_path.dentry->d_sb; 194 int err = 0; 195 196 /* device */ 197 if (sb->s_op->show_devname) { 198 seq_puts(m, "device "); 199 err = sb->s_op->show_devname(m, mnt_path.dentry); 200 } else { 201 if (r->mnt_devname) { 202 seq_puts(m, "device "); 203 mangle(m, r->mnt_devname); 204 } else 205 seq_puts(m, "no device"); 206 } 207 208 /* mount point */ 209 seq_puts(m, " mounted on "); 210 /* mountpoints outside of chroot jail will give SEQ_SKIP on this */ 211 err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\"); 212 if (err) 213 goto out; 214 seq_putc(m, ' '); 215 216 /* file system type */ 217 seq_puts(m, "with fstype "); 218 show_type(m, sb); 219 220 /* optional statistics */ 221 if (sb->s_op->show_stats) { 222 seq_putc(m, ' '); 223 if (!err) 224 err = sb->s_op->show_stats(m, mnt_path.dentry); 225 } 226 227 seq_putc(m, '\n'); 228 out: 229 return err; 230 } 231 232 static int mounts_open_common(struct inode *inode, struct file *file, 233 int (*show)(struct seq_file *, struct vfsmount *)) 234 { 235 struct task_struct *task = get_proc_task(inode); 236 struct nsproxy *nsp; 237 struct mnt_namespace *ns = NULL; 238 struct path root; 239 struct proc_mounts *p; 240 struct seq_file *m; 241 int ret = -EINVAL; 242 243 if (!task) 244 goto err; 245 246 task_lock(task); 247 nsp = task->nsproxy; 248 if (!nsp || !nsp->mnt_ns) { 249 task_unlock(task); 250 put_task_struct(task); 251 goto err; 252 } 253 ns = nsp->mnt_ns; 254 get_mnt_ns(ns); 255 if (!task->fs) { 256 task_unlock(task); 257 put_task_struct(task); 258 ret = -ENOENT; 259 goto err_put_ns; 260 } 261 get_fs_root(task->fs, &root); 262 task_unlock(task); 263 put_task_struct(task); 264 265 ret = seq_open_private(file, &mounts_op, sizeof(struct proc_mounts)); 266 if (ret) 267 goto err_put_path; 268 269 m = file->private_data; 270 m->poll_event = ns->event; 271 272 p = m->private; 273 p->ns = ns; 274 p->root = root; 275 p->show = show; 276 p->cached_event = ~0ULL; 277 278 return 0; 279 280 err_put_path: 281 path_put(&root); 282 err_put_ns: 283 put_mnt_ns(ns); 284 err: 285 return ret; 286 } 287 288 static int mounts_release(struct inode *inode, struct file *file) 289 { 290 struct seq_file *m = file->private_data; 291 struct proc_mounts *p = m->private; 292 path_put(&p->root); 293 put_mnt_ns(p->ns); 294 return seq_release_private(inode, file); 295 } 296 297 static int mounts_open(struct inode *inode, struct file *file) 298 { 299 return mounts_open_common(inode, file, show_vfsmnt); 300 } 301 302 static int mountinfo_open(struct inode *inode, struct file *file) 303 { 304 return mounts_open_common(inode, file, show_mountinfo); 305 } 306 307 static int mountstats_open(struct inode *inode, struct file *file) 308 { 309 return mounts_open_common(inode, file, show_vfsstat); 310 } 311 312 const struct file_operations proc_mounts_operations = { 313 .open = mounts_open, 314 .read = seq_read, 315 .llseek = seq_lseek, 316 .release = mounts_release, 317 .poll = mounts_poll, 318 }; 319 320 const struct file_operations proc_mountinfo_operations = { 321 .open = mountinfo_open, 322 .read = seq_read, 323 .llseek = seq_lseek, 324 .release = mounts_release, 325 .poll = mounts_poll, 326 }; 327 328 const struct file_operations proc_mountstats_operations = { 329 .open = mountstats_open, 330 .read = seq_read, 331 .llseek = seq_lseek, 332 .release = mounts_release, 333 }; 334