On Fri, 2017-05-26 at 11:28 -0400, Scott Mayhew wrote: > On Fri, 26 May 2017, Stephen Smalley wrote: > > > On Thu, 2017-05-25 at 17:07 -0400, Scott Mayhew wrote: > > > When the client traverses from filesystem exported without the > > > "security_label" option to one exported with the "security_label" > > > option, it needs to pass SECURITY_LSM_NATIVE_LABELS to > > > security_sb_set_mnt_opts() so that the new superblock has > > > SBLABEL_MNT > > > set in its security mount options. Otherwise, attempts to set > > > security > > > labels via setxattr over NFSv4.2 will fail. > > > > > > Signed-off-by: Scott Mayhew <smayhew@xxxxxxxxxx> > > > --- > > > fs/nfs/super.c | 23 ++++++++++++++++++++++- > > > 1 file changed, 22 insertions(+), 1 deletion(-) > > > > > > diff --git a/fs/nfs/super.c b/fs/nfs/super.c > > > index 2f3822a..d7a3b89 100644 > > > --- a/fs/nfs/super.c > > > +++ b/fs/nfs/super.c > > > @@ -2544,10 +2544,31 @@ EXPORT_SYMBOL_GPL(nfs_set_sb_security); > > > int nfs_clone_sb_security(struct super_block *s, struct dentry > > > *mntroot, > > > struct nfs_mount_info *mount_info) > > > { > > > + int error; > > > + unsigned long kflags = 0, kflags_out = 0; > > > + struct security_mnt_opts opts; > > > + > > > /* clone any lsm security options from the parent to the > > > new > > > sb */ > > > if (d_inode(mntroot)->i_op != NFS_SB(s)->nfs_client- > > > > rpc_ops->dir_inode_ops) > > > > > > return -ESTALE; > > > - return security_sb_clone_mnt_opts(mount_info->cloned- > > > >sb, > > > s); > > > + error = security_sb_clone_mnt_opts(mount_info->cloned- > > > >sb, > > > s); > > > + if (error) > > > + goto err; > > > + > > > + if (NFS_SB(s)->caps & NFS_CAP_SECURITY_LABEL && > > > + !(NFS_SB(mount_info->cloned->sb)->caps & > > > NFS_CAP_SECURITY_LABEL)) { > > > + memset(&opts, 0, sizeof(opts)); > > > + kflags |= SECURITY_LSM_NATIVE_LABELS; > > > + > > > + error = security_sb_set_mnt_opts(s, &opts, > > > kflags, > > > &kflags_out); > > > + if (error) > > > + goto err; > > > + > > > + if (!(kflags_out & SECURITY_LSM_NATIVE_LABELS)) > > > + NFS_SB(s)->caps &= > > > ~NFS_CAP_SECURITY_LABEL; > > > + } > > > +err: > > > + return error; > > > } > > > EXPORT_SYMBOL_GPL(nfs_clone_sb_security); > > > > Could this clobber a context set via context= mount option? > > Argh, yes I suppose it could. In my first attempt to fix this, I > added > a security_sb_get_mnt_opts() hook to get the original mount options > and > then passed that along with the SECURITY_LSM_NATIVE_LABELS flag to > security_sb_set_mnt_opts(). When I saw that > security_sb_set_mnt_opts() > wouldn't allow me to change a superblock that had already been > initialized, I got rid of the hook and added the check in patch 1... > maybe a combination of the two is needed? > > Testing it again now, I'm not sure the context= mount option is > working > correctly with the latest kernel. Looks like you are correct, https://github.com/SELinuxProject/selinux-kernel/issues/35 -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html