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Commit fd4a0edf authored by Miklos Szeredi's avatar Miklos Szeredi
Browse files

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: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 2a07a1f5

fs/namei.c

+21 −0
Original line number Diff line number Diff line
@@ -4668,6 +4668,27 @@ int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 
}

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

fs/nfsd/nfs4xdr.c

+4 −4
Original line number Diff line number Diff line
@@ -3576,10 +3576,10 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd 
	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);

fs/nfsd/vfs.c

+2 −4
Original line number Diff line number Diff line
@@ -1451,7 +1451,6 @@ do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp, 
__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 @@ nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp) 


	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 @@ nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp) 
	 */



	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)

fs/stat.c

+5 −3
Original line number Diff line number Diff line
@@ -329,12 +329,14 @@ SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname, 
		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);

fs/xfs/xfs_ioctl.c

+2 −2
Original line number Diff line number Diff line
@@ -287,7 +287,7 @@ xfs_readlink_by_handle( 
		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 @@ xfs_readlink_by_handle( 
		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);