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                 { MS_LAZYTIME, ",lazytime" },
  48                 { 0, NULL }
  49         };
  50         const struct proc_fs_info *fs_infop;
  51
  52         for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
  53                 if (sb->s_flags & fs_infop->flag)
  54                         seq_puts(m, fs_infop->str);
  55         }
  56
  57         return security_sb_show_options(m, sb);
  58 }
  59
  60 static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt)
  61 {
  62         static const struct proc_fs_info mnt_info[] = {
  63                 { MNT_NOSUID, ",nosuid" },
  64                 { MNT_NODEV, ",nodev" },
  65                 { MNT_NOEXEC, ",noexec" },
  66                 { MNT_NOATIME, ",noatime" },
  67                 { MNT_NODIRATIME, ",nodiratime" },
  68                 { MNT_RELATIME, ",relatime" },
  69                 { 0, NULL }
  70         };
  71         const struct proc_fs_info *fs_infop;
  72
  73         for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
  74                 if (mnt->mnt_flags & fs_infop->flag)
  75                         seq_puts(m, fs_infop->str);
  76         }
  77 }
  78
  79 static inline void mangle(struct seq_file *m, const char *s)
  80 {
  81         seq_escape(m, s, " \t\n\\");
  82 }
  83
  84 static void show_type(struct seq_file *m, struct super_block *sb)
  85 {
  86         mangle(m, sb->s_type->name);
  87         if (sb->s_subtype && sb->s_subtype[0]) {
  88                 seq_putc(m, '.');
  89                 mangle(m, sb->s_subtype);
  90         }
  91 }
  92
  93 static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt)
  94 {
  95         struct proc_mounts *p = proc_mounts(m);
  96         struct mount *r = real_mount(mnt);
  97         int err = 0;
  98         struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
  99         struct super_block *sb = mnt_path.dentry->d_sb;
 100
 101         if (sb->s_op->show_devname) {
 102                 err = sb->s_op->show_devname(m, mnt_path.dentry);
 103                 if (err)
 104                         goto out;
 105         } else {
 106                 mangle(m, r->mnt_devname ? r->mnt_devname : "none");
 107         }
 108         seq_putc(m, ' ');
 109         /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
 110         err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
 111         if (err)
 112                 goto out;
 113         seq_putc(m, ' ');
 114         show_type(m, sb);
 115         seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
 116         err = show_sb_opts(m, sb);
 117         if (err)
 118                 goto out;
 119         show_mnt_opts(m, mnt);
 120         if (sb->s_op->show_options)
 121                 err = sb->s_op->show_options(m, mnt_path.dentry);
 122         seq_puts(m, " 0 0\n");
 123 out:
 124         return err;
 125 }
 126
 127 static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt)
 128 {
 129         struct proc_mounts *p = proc_mounts(m);
 130         struct mount *r = real_mount(mnt);
 131         struct super_block *sb = mnt->mnt_sb;
 132         struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
 133         int err = 0;
 134
 135         seq_printf(m, "%i %i %u:%u ", r->mnt_id, r->mnt_parent->mnt_id,
 136                    MAJOR(sb->s_dev), MINOR(sb->s_dev));
 137         if (sb->s_op->show_path)
 138                 err = sb->s_op->show_path(m, mnt->mnt_root);
 139         else
 140                 seq_dentry(m, mnt->mnt_root, " \t\n\\");
 141         if (err)
 142                 goto out;
 143         seq_putc(m, ' ');
 144
 145         /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
 146         err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
 147         if (err)
 148                 goto out;
 149
 150         seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
 151         show_mnt_opts(m, mnt);
 152
 153         /* Tagged fields ("foo:X" or "bar") */
 154         if (IS_MNT_SHARED(r))
 155                 seq_printf(m, " shared:%i", r->mnt_group_id);
 156         if (IS_MNT_SLAVE(r)) {
 157                 int master = r->mnt_master->mnt_group_id;
 158                 int dom = get_dominating_id(r, &p->root);
 159                 seq_printf(m, " master:%i", master);
 160                 if (dom && dom != master)
 161                         seq_printf(m, " propagate_from:%i", dom);
 162         }
 163         if (IS_MNT_UNBINDABLE(r))
 164                 seq_puts(m, " unbindable");
 165
 166         /* Filesystem specific data */
 167         seq_puts(m, " - ");
 168         show_type(m, sb);
 169         seq_putc(m, ' ');
 170         if (sb->s_op->show_devname)
 171                 err = sb->s_op->show_devname(m, mnt->mnt_root);
 172         else
 173                 mangle(m, r->mnt_devname ? r->mnt_devname : "none");
 174         if (err)
 175                 goto out;
 176         seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw");
 177         err = show_sb_opts(m, sb);
 178         if (err)
 179                 goto out;
 180         if (sb->s_op->show_options)
 181                 err = sb->s_op->show_options(m, mnt->mnt_root);
 182         seq_putc(m, '\n');
 183 out:
 184         return err;
 185 }
 186
 187 static int show_vfsstat(struct seq_file *m, struct vfsmount *mnt)
 188 {
 189         struct proc_mounts *p = proc_mounts(m);
 190         struct mount *r = real_mount(mnt);
 191         struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
 192         struct super_block *sb = mnt_path.dentry->d_sb;
 193         int err = 0;
 194
 195         /* device */
 196         if (sb->s_op->show_devname) {
 197                 seq_puts(m, "device ");
 198                 err = sb->s_op->show_devname(m, mnt_path.dentry);
 199         } else {
 200                 if (r->mnt_devname) {
 201                         seq_puts(m, "device ");
 202                         mangle(m, r->mnt_devname);
 203                 } else
 204                         seq_puts(m, "no device");
 205         }
 206
 207         /* mount point */
 208         seq_puts(m, " mounted on ");
 209         /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
 210         err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
 211         if (err)
 212                 goto out;
 213         seq_putc(m, ' ');
 214
 215         /* file system type */
 216         seq_puts(m, "with fstype ");
 217         show_type(m, sb);
 218
 219         /* optional statistics */
 220         if (sb->s_op->show_stats) {
 221                 seq_putc(m, ' ');
 222                 if (!err)
 223                         err = sb->s_op->show_stats(m, mnt_path.dentry);
 224         }
 225
 226         seq_putc(m, '\n');
 227 out:
 228         return err;
 229 }
 230
 231 static int mounts_open_common(struct inode *inode, struct file *file,
 232                               int (*show)(struct seq_file *, struct vfsmount *))
 233 {
 234         struct task_struct *task = get_proc_task(inode);
 235         struct nsproxy *nsp;
 236         struct mnt_namespace *ns = NULL;
 237         struct path root;
 238         struct proc_mounts *p;
 239         int ret = -EINVAL;
 240
 241         if (!task)
 242                 goto err;
 243
 244         task_lock(task);
 245         nsp = task->nsproxy;
 246         if (!nsp || !nsp->mnt_ns) {
 247                 task_unlock(task);
 248                 put_task_struct(task);
 249                 goto err;
 250         }
 251         ns = nsp->mnt_ns;
 252         get_mnt_ns(ns);
 253         if (!task->fs) {
 254                 task_unlock(task);
 255                 put_task_struct(task);
 256                 ret = -ENOENT;
 257                 goto err_put_ns;
 258         }
 259         get_fs_root(task->fs, &root);
 260         task_unlock(task);
 261         put_task_struct(task);
 262
 263         ret = -ENOMEM;
 264         p = kmalloc(sizeof(struct proc_mounts), GFP_KERNEL);
 265         if (!p)
 266                 goto err_put_path;
 267
 268         file->private_data = &p->m;
 269         ret = seq_open(file, &mounts_op);
 270         if (ret)
 271                 goto err_free;
 272
 273         p->ns = ns;
 274         p->root = root;
 275         p->m.poll_event = ns->event;
 276         p->show = show;
 277         p->cached_event = ~0ULL;
 278
 279         return 0;
 280
 281  err_free:
 282         kfree(p);
 283  err_put_path:
 284         path_put(&root);
 285  err_put_ns:
 286         put_mnt_ns(ns);
 287  err:
 288         return ret;
 289 }
 290
 291 static int mounts_release(struct inode *inode, struct file *file)
 292 {
 293         struct proc_mounts *p = proc_mounts(file->private_data);
 294         path_put(&p->root);
 295         put_mnt_ns(p->ns);
 296         return seq_release(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 };