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Date: Mon, 25 Jul 2016 13:54:26 -0700 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, David Sinquin <david@...quin.eu>, Christoph Hellwig <hch@...radead.org>, Al Viro <viro@...iv.linux.org.uk>, "J. Bruce Fields" <bfields@...hat.com> Subject: [PATCH 4.6 051/203] nfsd: check permissions when setting ACLs 4.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ben Hutchings <ben@...adent.org.uk> commit 999653786df6954a31044528ac3f7a5dadca08f4 upstream. 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: David Sinquin <david@...quin.eu> [agreunba@...hat.com: use set_posix_acl] Fixes: 4ac7249e Cc: Christoph Hellwig <hch@...radead.org> Cc: Al Viro <viro@...iv.linux.org.uk> Signed-off-by: J. Bruce Fields <bfields@...hat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- fs/nfsd/nfs2acl.c | 20 ++++++++++---------- fs/nfsd/nfs3acl.c | 16 +++++++--------- fs/nfsd/nfs4acl.c | 16 ++++++++-------- 3 files changed, 25 insertions(+), 27 deletions(-) --- a/fs/nfsd/nfs2acl.c +++ b/fs/nfsd/nfs2acl.c @@ -104,22 +104,21 @@ static __be32 nfsacld_proc_setacl(struct 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 @@ out: 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); --- a/fs/nfsd/nfs3acl.c +++ b/fs/nfsd/nfs3acl.c @@ -95,22 +95,20 @@ static __be32 nfsd3_proc_setacl(struct s 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); --- a/fs/nfsd/nfs4acl.c +++ b/fs/nfsd/nfs4acl.c @@ -770,9 +770,6 @@ nfsd4_set_nfs4_acl(struct svc_rqst *rqst 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 *rqst 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:
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