fs/proc_namespace.c

   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                 if (err)
 201                         goto out;
 202         } else {
 203                 if (r->mnt_devname) {
 204                         seq_puts(m, "device ");
 205                         mangle(m, r->mnt_devname);
 206                 } else
 207                         seq_puts(m, "no device");
 208         }
 209
 210         /* mount point */
 211         seq_puts(m, " mounted on ");
 212         /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
 213         err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
 214         if (err)
 215                 goto out;
 216         seq_putc(m, ' ');
 217
 218         /* file system type */
 219         seq_puts(m, "with fstype ");
 220         show_type(m, sb);
 221
 222         /* optional statistics */
 223         if (sb->s_op->show_stats) {
 224                 seq_putc(m, ' ');
 225                 if (!err)
 226                         err = sb->s_op->show_stats(m, mnt_path.dentry);
 227         }
 228
 229         seq_putc(m, '\n');
 230 out:
 231         return err;
 232 }
 233
 234 static int mounts_open_common(struct inode *inode, struct file *file,
 235                               int (*show)(struct seq_file *, struct vfsmount *))
 236 {
 237         struct task_struct *task = get_proc_task(inode);
 238         struct nsproxy *nsp;
 239         struct mnt_namespace *ns = NULL;
 240         struct path root;
 241         struct proc_mounts *p;
 242         struct seq_file *m;
 243         int ret = -EINVAL;
 244
 245         if (!task)
 246                 goto err;
 247
 248         task_lock(task);
 249         nsp = task->nsproxy;
 250         if (!nsp || !nsp->mnt_ns) {
 251                 task_unlock(task);
 252                 put_task_struct(task);
 253                 goto err;
 254         }
 255         ns = nsp->mnt_ns;
 256         get_mnt_ns(ns);
 257         if (!task->fs) {
 258                 task_unlock(task);
 259                 put_task_struct(task);
 260                 ret = -ENOENT;
 261                 goto err_put_ns;
 262         }
 263         get_fs_root(task->fs, &root);
 264         task_unlock(task);
 265         put_task_struct(task);
 266
 267         ret = seq_open_private(file, &mounts_op, sizeof(struct proc_mounts));
 268         if (ret)
 269                 goto err_put_path;
 270
 271         m = file->private_data;
 272         m->poll_event = ns->event;
 273
 274         p = m->private;
 275         p->ns = ns;
 276         p->root = root;
 277         p->show = show;
 278         p->cached_event = ~0ULL;
 279
 280         return 0;
 281
 282  err_put_path:
 283         path_put(&root);
 284  err_put_ns:
 285         put_mnt_ns(ns);
 286  err:
 287         return ret;
 288 }
 289
 290 static int mounts_release(struct inode *inode, struct file *file)
 291 {
 292         struct seq_file *m = file->private_data;
 293         struct proc_mounts *p = m->private;
 294         path_put(&p->root);
 295         put_mnt_ns(p->ns);
 296         return seq_release_private(inode, file);
 297 }
 298
 299 static int mounts_open(struct inode *inode, struct file *file)
 300 {
 301         return mounts_open_common(inode, file, show_vfsmnt);
 302 }
 303
 304 static int mountinfo_open(struct inode *inode, struct file *file)
 305 {
 306         return mounts_open_common(inode, file, show_mountinfo);
 307 }
 308
 309 static int mountstats_open(struct inode *inode, struct file *file)
 310 {
 311         return mounts_open_common(inode, file, show_vfsstat);
 312 }
 313
 314 const struct file_operations proc_mounts_operations = {
 315         .open           = mounts_open,
 316         .read           = seq_read,
 317         .llseek         = seq_lseek,
 318         .release        = mounts_release,
 319         .poll           = mounts_poll,
 320 };
 321
 322 const struct file_operations proc_mountinfo_operations = {
 323         .open           = mountinfo_open,
 324         .read           = seq_read,
 325         .llseek         = seq_lseek,
 326         .release        = mounts_release,
 327         .poll           = mounts_poll,
 328 };
 329
 330 const struct file_operations proc_mountstats_operations = {
 331         .open           = mountstats_open,
 332         .read           = seq_read,
 333         .llseek         = seq_lseek,
 334         .release        = mounts_release,
 335 };