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