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Commit 99965378 authored by Ben Hutchings's avatar Ben Hutchings Committed by J. Bruce Fields
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nfsd: check permissions when setting ACLs 



Use set_posix_acl, which includes proper permission checks, instead of
calling ->set_acl directly.  Without this anyone may be able to grant
themselves permissions to a file by setting the ACL.

Lock the inode to make the new checks atomic with respect to set_acl.
(Also, nfsd was the only caller of set_acl not locking the inode, so I
suspect this may fix other races.)

This also simplifies the code, and ensures our ACLs are checked by
posix_acl_valid.

The permission checks and the inode locking were lost with commit
4ac7249e, which changed nfsd to use the set_acl inode operation directly
instead of going through xattr handlers.

Reported-by: default avatarDavid Sinquin <david@sinquin.eu>
[agreunba@redhat.com: use set_posix_acl]
Fixes: 4ac7249e
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent 485e71e8

fs/nfsd/nfs2acl.c

+10 −10
Original line number Diff line number Diff line
@@ -104,22 +104,21 @@ static __be32 nfsacld_proc_setacl(struct svc_rqst * rqstp, 
		goto out;



	inode = d_inode(fh->fh_dentry);

	if (!IS_POSIXACL(inode) || !inode->i_op->set_acl) {

		error = -EOPNOTSUPP;

		goto out_errno;

	}



	error = fh_want_write(fh);

	if (error)

		goto out_errno;



	error = inode->i_op->set_acl(inode, argp->acl_access, ACL_TYPE_ACCESS);

	fh_lock(fh);



	error = set_posix_acl(inode, ACL_TYPE_ACCESS, argp->acl_access);

	if (error)

		goto out_drop_write;

	error = inode->i_op->set_acl(inode, argp->acl_default,

				     ACL_TYPE_DEFAULT);

		goto out_drop_lock;

	error = set_posix_acl(inode, ACL_TYPE_DEFAULT, argp->acl_default);

	if (error)

		goto out_drop_write;

		goto out_drop_lock;



	fh_unlock(fh);



	fh_drop_write(fh);
@@ -131,7 +130,8 @@ static __be32 nfsacld_proc_setacl(struct svc_rqst * rqstp, 
	posix_acl_release(argp->acl_access);

	posix_acl_release(argp->acl_default);

	return nfserr;

out_drop_write:

out_drop_lock:

	fh_unlock(fh);

	fh_drop_write(fh);

out_errno:

	nfserr = nfserrno(error);

fs/nfsd/nfs3acl.c

+7 −9
Original line number Diff line number Diff line
@@ -95,22 +95,20 @@ static __be32 nfsd3_proc_setacl(struct svc_rqst * rqstp, 
		goto out;



	inode = d_inode(fh->fh_dentry);

	if (!IS_POSIXACL(inode) || !inode->i_op->set_acl) {

		error = -EOPNOTSUPP;

		goto out_errno;

	}



	error = fh_want_write(fh);

	if (error)

		goto out_errno;



	error = inode->i_op->set_acl(inode, argp->acl_access, ACL_TYPE_ACCESS);

	fh_lock(fh);



	error = set_posix_acl(inode, ACL_TYPE_ACCESS, argp->acl_access);

	if (error)

		goto out_drop_write;

	error = inode->i_op->set_acl(inode, argp->acl_default,

				     ACL_TYPE_DEFAULT);

		goto out_drop_lock;

	error = set_posix_acl(inode, ACL_TYPE_DEFAULT, argp->acl_default);



out_drop_write:

out_drop_lock:

	fh_unlock(fh);

	fh_drop_write(fh);

out_errno:

	nfserr = nfserrno(error);

fs/nfsd/nfs4acl.c

+8 −8
Original line number Diff line number Diff line
@@ -770,9 +770,6 @@ nfsd4_set_nfs4_acl(struct svc_rqst *rqstp, struct svc_fh *fhp, 
	dentry = fhp->fh_dentry;

	inode = d_inode(dentry);



	if (!inode->i_op->set_acl || !IS_POSIXACL(inode))

		return nfserr_attrnotsupp;



	if (S_ISDIR(inode->i_mode))

		flags = NFS4_ACL_DIR;
@@ -782,16 +779,19 @@ nfsd4_set_nfs4_acl(struct svc_rqst *rqstp, struct svc_fh *fhp, 
	if (host_error < 0)

		goto out_nfserr;



	host_error = inode->i_op->set_acl(inode, pacl, ACL_TYPE_ACCESS);

	fh_lock(fhp);



	host_error = set_posix_acl(inode, ACL_TYPE_ACCESS, pacl);

	if (host_error < 0)

		goto out_release;

		goto out_drop_lock;



	if (S_ISDIR(inode->i_mode)) {

		host_error = inode->i_op->set_acl(inode, dpacl,

						  ACL_TYPE_DEFAULT);

		host_error = set_posix_acl(inode, ACL_TYPE_DEFAULT, dpacl);

	}



out_release:

out_drop_lock:

	fh_unlock(fhp);



	posix_acl_release(pacl);

	posix_acl_release(dpacl);

out_nfserr: