[PATCH] r/o bind mounts: get callers of vfs_mknod/create/mkdir()
This takes care of all of the direct callers of vfs_mknod().
Since a few of these cases also handle normal file creation
as well, this also covers some calls to vfs_create().
So that we don't have to make three mnt_want/drop_write()
calls inside of the switch statement, we move some of its
logic outside of the switch and into a helper function
suggested by Christoph.
This also encapsulates a fix for mknod(S_IFREG) that Miklos
found.
[AV: merged mkdir handling, added missing nfsd pieces]
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/namei.c b/fs/namei.c
index 89ef317..3fbcf20 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1984,6 +1984,23 @@
return error;
}
+static int may_mknod(mode_t mode)
+{
+ switch (mode & S_IFMT) {
+ case S_IFREG:
+ case S_IFCHR:
+ case S_IFBLK:
+ case S_IFIFO:
+ case S_IFSOCK:
+ case 0: /* zero mode translates to S_IFREG */
+ return 0;
+ case S_IFDIR:
+ return -EPERM;
+ default:
+ return -EINVAL;
+ }
+}
+
asmlinkage long sys_mknodat(int dfd, const char __user *filename, int mode,
unsigned dev)
{
@@ -2002,12 +2019,19 @@
if (error)
goto out;
dentry = lookup_create(&nd, 0);
- error = PTR_ERR(dentry);
-
+ if (IS_ERR(dentry)) {
+ error = PTR_ERR(dentry);
+ goto out_unlock;
+ }
if (!IS_POSIXACL(nd.path.dentry->d_inode))
mode &= ~current->fs->umask;
- if (!IS_ERR(dentry)) {
- switch (mode & S_IFMT) {
+ error = may_mknod(mode);
+ if (error)
+ goto out_dput;
+ error = mnt_want_write(nd.path.mnt);
+ if (error)
+ goto out_dput;
+ switch (mode & S_IFMT) {
case 0: case S_IFREG:
error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd);
break;
@@ -2018,14 +2042,11 @@
case S_IFIFO: case S_IFSOCK:
error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0);
break;
- case S_IFDIR:
- error = -EPERM;
- break;
- default:
- error = -EINVAL;
- }
- dput(dentry);
}
+ mnt_drop_write(nd.path.mnt);
+out_dput:
+ dput(dentry);
+out_unlock:
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
path_put(&nd.path);
out:
@@ -2083,7 +2104,12 @@
if (!IS_POSIXACL(nd.path.dentry->d_inode))
mode &= ~current->fs->umask;
+ error = mnt_want_write(nd.path.mnt);
+ if (error)
+ goto out_dput;
error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode);
+ mnt_drop_write(nd.path.mnt);
+out_dput:
dput(dentry);
out_unlock:
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
index 4e77a1a..145b3c8 100644
--- a/fs/nfsd/nfs4recover.c
+++ b/fs/nfsd/nfs4recover.c
@@ -155,7 +155,11 @@
dprintk("NFSD: nfsd4_create_clid_dir: DIRECTORY EXISTS\n");
goto out_put;
}
+ status = mnt_want_write(rec_dir.path.mnt);
+ if (status)
+ goto out_put;
status = vfs_mkdir(rec_dir.path.dentry->d_inode, dentry, S_IRWXU);
+ mnt_drop_write(rec_dir.path.mnt);
out_put:
dput(dentry);
out_unlock:
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index efff58a..14d5824 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1255,23 +1255,35 @@
err = 0;
switch (type) {
case S_IFREG:
+ host_err = mnt_want_write(fhp->fh_export->ex_path.mnt);
+ if (host_err)
+ goto out_nfserr;
host_err = vfs_create(dirp, dchild, iap->ia_mode, NULL);
break;
case S_IFDIR:
+ host_err = mnt_want_write(fhp->fh_export->ex_path.mnt);
+ if (host_err)
+ goto out_nfserr;
host_err = vfs_mkdir(dirp, dchild, iap->ia_mode);
break;
case S_IFCHR:
case S_IFBLK:
case S_IFIFO:
case S_IFSOCK:
+ host_err = mnt_want_write(fhp->fh_export->ex_path.mnt);
+ if (host_err)
+ goto out_nfserr;
host_err = vfs_mknod(dirp, dchild, iap->ia_mode, rdev);
break;
default:
printk("nfsd: bad file type %o in nfsd_create\n", type);
host_err = -EINVAL;
- }
- if (host_err < 0)
goto out_nfserr;
+ }
+ if (host_err < 0) {
+ mnt_drop_write(fhp->fh_export->ex_path.mnt);
+ goto out_nfserr;
+ }
if (EX_ISSYNC(fhp->fh_export)) {
err = nfserrno(nfsd_sync_dir(dentry));
@@ -1282,6 +1294,7 @@
err2 = nfsd_create_setattr(rqstp, resfhp, iap);
if (err2)
err = err2;
+ mnt_drop_write(fhp->fh_export->ex_path.mnt);
/*
* Update the file handle to get the new inode info.
*/
@@ -1359,6 +1372,9 @@
v_atime = verifier[1]&0x7fffffff;
}
+ host_err = mnt_want_write(fhp->fh_export->ex_path.mnt);
+ if (host_err)
+ goto out_nfserr;
if (dchild->d_inode) {
err = 0;
@@ -1390,12 +1406,15 @@
case NFS3_CREATE_GUARDED:
err = nfserr_exist;
}
+ mnt_drop_write(fhp->fh_export->ex_path.mnt);
goto out;
}
host_err = vfs_create(dirp, dchild, iap->ia_mode, NULL);
- if (host_err < 0)
+ if (host_err < 0) {
+ mnt_drop_write(fhp->fh_export->ex_path.mnt);
goto out_nfserr;
+ }
if (created)
*created = 1;
@@ -1420,6 +1439,7 @@
if (err2)
err = err2;
+ mnt_drop_write(fhp->fh_export->ex_path.mnt);
/*
* Update the filehandle to get the new inode info.
*/