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/sunrpc/svc.h>
  11 #include <linux/nfsd/nfsd.h>
  12 #include <linux/nfsd/syscall.h>
  13 #include <linux/cred.h>
  14 #include <linux/sched.h>
  15 #include <linux/linkage.h>
  16 #include <linux/namei.h>
  17 #include <linux/mount.h>
  18 #include <linux/syscalls.h>
  19 #include <asm/uaccess.h>
  20
  21 /*
  22  * open a file on nfsd fs
  23  */
  24
  25 static struct file *do_open(char *name, int flags)
  26 {
  27         struct nameidata nd;
  28         struct vfsmount *mnt;
  29         int error;
  30
  31         mnt = do_kern_mount("nfsd", 0, "nfsd", NULL);
  32         if (IS_ERR(mnt))
  33                 return (struct file *)mnt;
  34
  35         error = vfs_path_lookup(mnt->mnt_root, mnt, name, 0, &nd);
  36         mntput(mnt);    /* drop do_kern_mount reference */
  37         if (error)
  38                 return ERR_PTR(error);
  39
  40         if (flags == O_RDWR)
  41                 error = may_open(&nd.path, MAY_READ|MAY_WRITE,
  42                                            FMODE_READ|FMODE_WRITE);
  43         else
  44                 error = may_open(&nd.path, MAY_WRITE, FMODE_WRITE);
  45
  46         if (!error)
  47                 return dentry_open(nd.path.dentry, nd.path.mnt, flags,
  48                                    current_cred());
  49
  50         path_put(&nd.path);
  51         return ERR_PTR(error);
  52 }
  53
  54 static struct {
  55         char *name; int wsize; int rsize;
  56 } map[] = {
  57         [NFSCTL_SVC] = {
  58                 .name   = ".svc",
  59                 .wsize  = sizeof(struct nfsctl_svc)
  60         },
  61         [NFSCTL_ADDCLIENT] = {
  62                 .name   = ".add",
  63                 .wsize  = sizeof(struct nfsctl_client)
  64         },
  65         [NFSCTL_DELCLIENT] = {
  66                 .name   = ".del",
  67                 .wsize  = sizeof(struct nfsctl_client)
  68         },
  69         [NFSCTL_EXPORT] = {
  70                 .name   = ".export",
  71                 .wsize  = sizeof(struct nfsctl_export)
  72         },
  73         [NFSCTL_UNEXPORT] = {
  74                 .name   = ".unexport",
  75                 .wsize  = sizeof(struct nfsctl_export)
  76         },
  77         [NFSCTL_GETFD] = {
  78                 .name   = ".getfd",
  79                 .wsize  = sizeof(struct nfsctl_fdparm),
  80                 .rsize  = NFS_FHSIZE
  81         },
  82         [NFSCTL_GETFS] = {
  83                 .name   = ".getfs",
  84                 .wsize  = sizeof(struct nfsctl_fsparm),
  85                 .rsize  = sizeof(struct knfsd_fh)
  86         },
  87 };
  88
  89 SYSCALL_DEFINE3(nfsservctl, int, cmd, struct nfsctl_arg __user *, arg,
  90                 void __user *, res)
  91 {
  92         struct file *file;
  93         void __user *p = &arg->u;
  94         int version;
  95         int err;
  96
  97         if (copy_from_user(&version, &arg->ca_version, sizeof(int)))
  98                 return -EFAULT;
  99
 100         if (version != NFSCTL_VERSION)
 101                 return -EINVAL;
 102
 103         if (cmd < 0 || cmd >= ARRAY_SIZE(map) || !map[cmd].name)
 104                 return -EINVAL;
 105
 106         file = do_open(map[cmd].name, map[cmd].rsize ? O_RDWR : O_WRONLY);
 107         if (IS_ERR(file))
 108                 return PTR_ERR(file);
 109         err = file->f_op->write(file, p, map[cmd].wsize, &file->f_pos);
 110         if (err >= 0 && map[cmd].rsize)
 111                 err = file->f_op->read(file, res, map[cmd].rsize, &file->f_pos);
 112         if (err >= 0)
 113                 err = 0;
 114         fput(file);
 115         return err;
 116 }