From mboxrd@z Thu Jan 1 00:00:00 1970 Reply-To: kernel-hardening@lists.openwall.com From: Elena Reshetova Date: Fri, 29 Jul 2016 10:34:39 +0300 Message-Id: <1469777680-3687-5-git-send-email-elena.reshetova@intel.com> In-Reply-To: <1469777680-3687-1-git-send-email-elena.reshetova@intel.com> References: <1469777680-3687-1-git-send-email-elena.reshetova@intel.com> Subject: [kernel-hardening] [RFC] [PATCH 4/5] invoke path_chroot() LSM hook on mntns_install() To: kernel-hardening@lists.openwall.com Cc: linux-security-module@vger.kernel.org, keescook@chromium.org, spender@grsecurity.net, jmorris@namei.org, casey.schaufler@intel.com, michael.leibowitz@intel.com, william.c.roberts@intel.com, Elena Reshetova List-ID: This adds an additional invocation of the security_path_chroot LSM hook inside mntns_install(). Currently only capabilities are checked at this point, while process root actually changes. Signed-off-by: Elena Reshetova --- fs/namespace.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index 419f746..c5dcb09 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -3325,6 +3325,7 @@ static int mntns_install(struct nsproxy *nsproxy, struct ns_common *ns) struct fs_struct *fs = current->fs; struct mnt_namespace *mnt_ns = to_mnt_ns(ns); struct path root; + int retval; if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) || !ns_capable(current_user_ns(), CAP_SYS_CHROOT) || @@ -3334,10 +3335,6 @@ static int mntns_install(struct nsproxy *nsproxy, struct ns_common *ns) if (fs->users != 1) return -EINVAL; - get_mnt_ns(mnt_ns); - put_mnt_ns(nsproxy->mnt_ns); - nsproxy->mnt_ns = mnt_ns; - /* Find the root */ root.mnt = &mnt_ns->root->mnt; root.dentry = mnt_ns->root->mnt.mnt_root; @@ -3345,6 +3342,16 @@ static int mntns_install(struct nsproxy *nsproxy, struct ns_common *ns) while(d_mountpoint(root.dentry) && follow_down_one(&root)) ; + retval = security_path_chroot(&root); + if (retval) { + path_put(&root); + return retval; + } + + get_mnt_ns(mnt_ns); + put_mnt_ns(nsproxy->mnt_ns); + nsproxy->mnt_ns = mnt_ns; + /* Update the pwd and root */ set_fs_pwd(fs, &root); set_fs_root(fs, &root); -- 1.9.1