fs/nfsctl.c

   1 /*
   2  *      fs/nfsctl.c
   3  *
   4  *      This should eventually move to userland.
   5  *
   6  */
   7 #include <linux/types.h>
   8 #include <linux/file.h>
   9 #include <linux/fs.h>
  10 #include <linux/nfsd/syscall.h>
  11 #include <linux/cred.h>
  12 #include <linux/sched.h>
  13 #include <linux/linkage.h>
  14 #include <linux/namei.h>
  15 #include <linux/mount.h>
  16 #include <linux/syscalls.h>
  17 #include <asm/uaccess.h>
  18
  19 /*
  20  * open a file on nfsd fs
  21  */
  22
  23 static struct file *do_open(char *name, int flags)
  24 {
  25         struct nameidata nd;
  26         struct vfsmount *mnt;
  27         int error;
  28
  29         mnt = do_kern_mount("nfsd", 0, "nfsd", NULL);
  30         if (IS_ERR(mnt))
  31                 return (struct file *)mnt;
  32
  33         error = vfs_path_lookup(mnt->mnt_root, mnt, name, 0, &nd);
  34         mntput(mnt);    /* drop do_kern_mount reference */
  35         if (error)
  36                 return ERR_PTR(error);
  37
  38         if (flags == O_RDWR)
  39                 error = may_open(&nd.path, MAY_READ|MAY_WRITE, flags);
  40         else
  41                 error = may_open(&nd.path, MAY_WRITE, flags);
  42
  43         if (!error)
  44                 return dentry_open(nd.path.dentry, nd.path.mnt, flags,
  45                                    current_cred());
  46
  47         path_put(&nd.path);
  48         return ERR_PTR(error);
  49 }
  50
  51 static struct {
  52         char *name; int wsize; int rsize;
  53 } map[] = {
  54         [NFSCTL_SVC] = {
  55                 .name   = ".svc",
  56                 .wsize  = sizeof(struct nfsctl_svc)
  57         },
  58         [NFSCTL_ADDCLIENT] = {
  59                 .name   = ".add",
  60                 .wsize  = sizeof(struct nfsctl_client)
  61         },
  62         [NFSCTL_DELCLIENT] = {
  63                 .name   = ".del",
  64                 .wsize  = sizeof(struct nfsctl_client)
  65         },
  66         [NFSCTL_EXPORT] = {
  67                 .name   = ".export",
  68                 .wsize  = sizeof(struct nfsctl_export)
  69         },
  70         [NFSCTL_UNEXPORT] = {
  71                 .name   = ".unexport",
  72                 .wsize  = sizeof(struct nfsctl_export)
  73         },
  74         [NFSCTL_GETFD] = {
  75                 .name   = ".getfd",
  76                 .wsize  = sizeof(struct nfsctl_fdparm),
  77                 .rsize  = NFS_FHSIZE
  78         },
  79         [NFSCTL_GETFS] = {
  80                 .name   = ".getfs",
  81                 .wsize  = sizeof(struct nfsctl_fsparm),
  82                 .rsize  = sizeof(struct knfsd_fh)
  83         },
  84 };
  85
  86 SYSCALL_DEFINE3(nfsservctl, int, cmd, struct nfsctl_arg __user *, arg,
  87                 void __user *, res)
  88 {
  89         struct file *file;
  90         void __user *p = &arg->u;
  91         int version;
  92         int err;
  93
  94         if (copy_from_user(&version, &arg->ca_version, sizeof(int)))
  95                 return -EFAULT;
  96
  97         if (version != NFSCTL_VERSION)
  98                 return -EINVAL;
  99
 100         if (cmd < 0 || cmd >= ARRAY_SIZE(map) || !map[cmd].name)
 101                 return -EINVAL;
 102
 103         file = do_open(map[cmd].name, map[cmd].rsize ? O_RDWR : O_WRONLY);
 104         if (IS_ERR(file))
 105                 return PTR_ERR(file);
 106         err = file->f_op->write(file, p, map[cmd].wsize, &file->f_pos);
 107         if (err >= 0 && map[cmd].rsize)
 108                 err = file->f_op->read(file, res, map[cmd].rsize, &file->f_pos);
 109         if (err >= 0)
 110                 err = 0;
 111         fput(file);
 112         return err;
 113 }