vfs: replace calling i_op->readlink with vfs_readlink()
Also check d_is_symlink() in callers instead of inode->i_op->readlink
because following patches will allow NULL ->readlink for symlinks.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
diff --git a/fs/namei.c b/fs/namei.c
index 5b4eed2..12a4159 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -4669,6 +4669,27 @@
EXPORT_SYMBOL(generic_readlink);
/**
+ * vfs_readlink - copy symlink body into userspace buffer
+ * @dentry: dentry on which to get symbolic link
+ * @buffer: user memory pointer
+ * @buflen: size of buffer
+ *
+ * Does not touch atime. That's up to the caller if necessary
+ *
+ * Does not call security hook.
+ */
+int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen)
+{
+ struct inode *inode = d_inode(dentry);
+
+ if (!inode->i_op->readlink)
+ return -EINVAL;
+
+ return inode->i_op->readlink(dentry, buffer, buflen);
+}
+EXPORT_SYMBOL(vfs_readlink);
+
+/**
* vfs_get_link - get symlink body
* @dentry: dentry on which to get symbolic link
* @done: caller needs to free returned data with this
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index c2d2895..645e1e3 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3576,10 +3576,10 @@
if (!p)
return nfserr_resource;
/*
- * XXX: By default, the ->readlink() VFS op will truncate symlinks
- * if they would overflow the buffer. Is this kosher in NFSv4? If
- * not, one easy fix is: if ->readlink() precisely fills the buffer,
- * assume that truncation occurred, and return NFS4ERR_RESOURCE.
+ * XXX: By default, vfs_readlink() will truncate symlinks if they
+ * would overflow the buffer. Is this kosher in NFSv4? If not, one
+ * easy fix is: if vfs_readlink() precisely fills the buffer, assume
+ * that truncation occurred, and return NFS4ERR_RESOURCE.
*/
nfserr = nfsd_readlink(readlink->rl_rqstp, readlink->rl_fhp,
(char *)p, &maxcount);
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 8ca642f..b854f02 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1451,7 +1451,6 @@
__be32
nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp)
{
- struct inode *inode;
mm_segment_t oldfs;
__be32 err;
int host_err;
@@ -1463,10 +1462,9 @@
path.mnt = fhp->fh_export->ex_path.mnt;
path.dentry = fhp->fh_dentry;
- inode = d_inode(path.dentry);
err = nfserr_inval;
- if (!inode->i_op->readlink)
+ if (!d_is_symlink(path.dentry))
goto out;
touch_atime(&path);
@@ -1475,7 +1473,7 @@
*/
oldfs = get_fs(); set_fs(KERNEL_DS);
- host_err = inode->i_op->readlink(path.dentry, (char __user *)buf, *lenp);
+ host_err = vfs_readlink(path.dentry, (char __user *)buf, *lenp);
set_fs(oldfs);
if (host_err < 0)
diff --git a/fs/stat.c b/fs/stat.c
index bc045c7..0b210c3 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -329,12 +329,14 @@
struct inode *inode = d_backing_inode(path.dentry);
error = empty ? -ENOENT : -EINVAL;
- if (inode->i_op->readlink) {
+ /*
+ * AFS mountpoints allow readlink(2) but are not symlinks
+ */
+ if (d_is_symlink(path.dentry) || inode->i_op->readlink) {
error = security_inode_readlink(path.dentry);
if (!error) {
touch_atime(&path);
- error = inode->i_op->readlink(path.dentry,
- buf, bufsiz);
+ error = vfs_readlink(path.dentry, buf, bufsiz);
}
}
path_put(&path);
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index c245bed..9b12f7c 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -287,7 +287,7 @@
return PTR_ERR(dentry);
/* Restrict this handle operation to symlinks only. */
- if (!d_inode(dentry)->i_op->readlink) {
+ if (!d_is_symlink(dentry)) {
error = -EINVAL;
goto out_dput;
}
@@ -297,7 +297,7 @@
goto out_dput;
}
- error = d_inode(dentry)->i_op->readlink(dentry, hreq->ohandle, olen);
+ error = vfs_readlink(dentry, hreq->ohandle, olen);
out_dput:
dput(dentry);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index dc0478c..eba20d1 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2935,6 +2935,7 @@
extern int vfs_fstat(unsigned int, struct kstat *);
extern int vfs_fstatat(int , const char __user *, struct kstat *, int);
extern const char *vfs_get_link(struct dentry *, struct delayed_call *);
+extern int vfs_readlink(struct dentry *, char __user *, int);
extern int __generic_block_fiemap(struct inode *inode,
struct fiemap_extent_info *fieinfo,