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authorBen Hutchings <ben@decadent.org.uk>2016-06-22 21:43:35 +0300
committerJ. Bruce Fields <bfields@redhat.com>2016-06-24 19:11:52 +0300
commit999653786df6954a31044528ac3f7a5dadca08f4 (patch)
tree1591ca7fc7acbd0128b33701516f85276ad8ff06 /fs/nfsd/nfs4acl.c
parent485e71e8fb6356c08c7fc6bcce4bf02c9a9a663f (diff)
downloadlinux-999653786df6954a31044528ac3f7a5dadca08f4.tar.xz
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: David 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: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'fs/nfsd/nfs4acl.c')
-rw-r--r--fs/nfsd/nfs4acl.c16
1 files changed, 8 insertions, 8 deletions
diff --git a/fs/nfsd/nfs4acl.c b/fs/nfsd/nfs4acl.c
index 6adabd6049b7..71292a0d6f09 100644
--- a/fs/nfsd/nfs4acl.c
+++ b/fs/nfsd/nfs4acl.c
@@ -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: