5.6.14-2 (clr 5.6.14-955) Add sysctl and CONFIG to disallow unprivileged CLONE_NEWUSER

3 files changed, 143 insertions, 3 deletions

diff --git a/.SRCINFO b/.SRCINFO
index 4ac38bd0b190..2cf211ecbf6e 100644
--- a/.SRCINFO
+++ b/.SRCINFO
@@ -1,7 +1,7 @@
 pkgbase = linux-clear
 	pkgdesc = Clear Linux
 	pkgver = 5.6.14
-	pkgrel = 1
+	pkgrel = 2
 	url = https://github.com/clearlinux-pkgs/linux
 	arch = x86_64
 	license = GPL2
@@ -18,6 +18,7 @@ pkgbase = linux-clear
 	source = clearlinux::git+https://github.com/clearlinux-pkgs/linux.git#tag=5.6.14-955
 	source = enable_additional_cpu_optimizations_for_gcc_v10.1+_kernel_v5.4-5.6_v1.patch
 	source = pci-enable-overrides-for-missing-acs-capabilities.patch
+	source = 0001-ZEN-Add-sysctl-and-CONFIG-to-disallow-unprivileged-C.patch
 	validpgpkeys = ABAF11C65A2970B130ABE3C479BE3E4300411886
 	validpgpkeys = 647F28654894E3BD457199BE38DBBDC86092693E
 	sha256sums = e342b04a2aa63808ea0ef1baab28fc520bd031ef8cf93d9ee4a31d4058fcb622
@@ -26,6 +27,7 @@ pkgbase = linux-clear
 	sha256sums = SKIP
 	sha256sums = c650fc6ff773e99dbc1fda9411b10b06513c5161791106c44d5a11dbcf6420f9
 	sha256sums = 2c98de0814366b041aeee4cbf82b82620c7834bc33752d50f089e8bd7ea5cf5e
+	sha256sums = bdd05caf94135898bceac0a9d14ec6b1b458dba162d00efd46a292fe97f2679b
 
 pkgname = linux-clear
 	pkgdesc = The Clear Linux kernel and modules
diff --git a/0001-ZEN-Add-sysctl-and-CONFIG-to-disallow-unprivileged-C.patch b/0001-ZEN-Add-sysctl-and-CONFIG-to-disallow-unprivileged-C.patch
new file mode 100644
index 000000000000..29abaacc2336
--- /dev/null
+++ b/0001-ZEN-Add-sysctl-and-CONFIG-to-disallow-unprivileged-C.patch
@@ -0,0 +1,132 @@
+From f4b254de5d2b75143dd7c225e58afb3f5ee3bae6 Mon Sep 17 00:00:00 2001
+From: "Jan Alexander Steffens (heftig)" <jan.steffens@gmail.com>
+Date: Mon, 16 Sep 2019 04:53:20 +0200
+Subject: [PATCH] ZEN: Add sysctl and CONFIG to disallow unprivileged
+ CLONE_NEWUSER
+
+Our default behavior continues to match the vanilla kernel.
+---
+ init/Kconfig            | 16 ++++++++++++++++
+ kernel/fork.c           | 15 +++++++++++++++
+ kernel/sysctl.c         | 12 ++++++++++++
+ kernel/user_namespace.c |  7 +++++++
+ 4 files changed, 50 insertions(+)
+
+diff --git a/init/Kconfig b/init/Kconfig
+index 6db3e310a5e4..2dd7dd1b6b0d 100644
+--- a/init/Kconfig
++++ b/init/Kconfig
+@@ -1083,6 +1083,22 @@ config USER_NS
+ 
+ 	  If unsure, say N.
+ 
++config USER_NS_UNPRIVILEGED
++	bool "Allow unprivileged users to create namespaces"
++	default y
++	depends on USER_NS
++	help
++	  When disabled, unprivileged users will not be able to create
++	  new namespaces. Allowing users to create their own namespaces
++	  has been part of several recent local privilege escalation
++	  exploits, so if you need user namespaces but are
++	  paranoid^Wsecurity-conscious you want to disable this.
++
++	  This setting can be overridden at runtime via the
++	  kernel.unprivileged_userns_clone sysctl.
++
++	  If unsure, say Y.
++
+ config PID_NS
+ 	bool "PID Namespaces"
+ 	default y
+diff --git a/kernel/fork.c b/kernel/fork.c
+index 9180f4416dba..a02f83b1d9b4 100644
+--- a/kernel/fork.c
++++ b/kernel/fork.c
+@@ -106,6 +106,11 @@
+ 
+ #define CREATE_TRACE_POINTS
+ #include <trace/events/task.h>
++#ifdef CONFIG_USER_NS
++extern int unprivileged_userns_clone;
++#else
++#define unprivileged_userns_clone 0
++#endif
+ 
+ /*
+  * Minimum number of threads to boot the kernel
+@@ -1779,6 +1784,10 @@ static __latent_entropy struct task_struct *copy_process(
+ 	if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS))
+ 		return ERR_PTR(-EINVAL);
+ 
++	if ((clone_flags & CLONE_NEWUSER) && !unprivileged_userns_clone)
++		if (!capable(CAP_SYS_ADMIN))
++			return ERR_PTR(-EPERM);
++
+ 	/*
+ 	 * Thread groups must share signals as well, and detached threads
+ 	 * can only be started up within the thread group.
+@@ -2837,6 +2846,12 @@ int ksys_unshare(unsigned long unshare_flags)
+ 	if (unshare_flags & CLONE_NEWNS)
+ 		unshare_flags |= CLONE_FS;
+ 
++	if ((unshare_flags & CLONE_NEWUSER) && !unprivileged_userns_clone) {
++		err = -EPERM;
++		if (!capable(CAP_SYS_ADMIN))
++			goto bad_unshare_out;
++	}
++
+ 	err = check_unshare_flags(unshare_flags);
+ 	if (err)
+ 		goto bad_unshare_out;
+diff --git a/kernel/sysctl.c b/kernel/sysctl.c
+index 70665934d53e..9797869ed829 100644
+--- a/kernel/sysctl.c
++++ b/kernel/sysctl.c
+@@ -110,6 +110,9 @@ extern int core_uses_pid;
+ extern char core_pattern[];
+ extern unsigned int core_pipe_limit;
+ #endif
++#ifdef CONFIG_USER_NS
++extern int unprivileged_userns_clone;
++#endif
+ extern int pid_max;
+ extern int pid_max_min, pid_max_max;
+ extern int percpu_pagelist_fraction;
+@@ -546,6 +549,15 @@ static struct ctl_table kern_table[] = {
+ 		.proc_handler	= proc_dointvec,
+ 	},
+ #endif
++#ifdef CONFIG_USER_NS
++	{
++		.procname	= "unprivileged_userns_clone",
++		.data		= &unprivileged_userns_clone,
++		.maxlen		= sizeof(int),
++		.mode		= 0644,
++		.proc_handler	= proc_dointvec,
++	},
++#endif
+ #ifdef CONFIG_PROC_SYSCTL
+ 	{
+ 		.procname	= "tainted",
+diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
+index 8eadadc478f9..c36ecd19562c 100644
+--- a/kernel/user_namespace.c
++++ b/kernel/user_namespace.c
+@@ -21,6 +21,13 @@
+ #include <linux/bsearch.h>
+ #include <linux/sort.h>
+ 
++/* sysctl */
++#ifdef CONFIG_USER_NS_UNPRIVILEGED
++int unprivileged_userns_clone = 1;
++#else
++int unprivileged_userns_clone;
++#endif
++
+ static struct kmem_cache *user_ns_cachep __read_mostly;
+ static DEFINE_MUTEX(userns_state_mutex);
+ 
+-- 
+2.26.2
+
diff --git a/PKGBUILD b/PKGBUILD
index c3f66d68c6c1..6fa3672122a1 100644
--- a/PKGBUILD
+++ b/PKGBUILD
@@ -71,7 +71,7 @@ _srcname=linux-${_major}
 _clr=${_major}.14-955
 pkgbase=linux-clear
 pkgver=${_major}.${_minor}
-pkgrel=1
+pkgrel=2
 pkgdesc='Clear Linux'
 arch=('x86_64')
 url="https://github.com/clearlinux-pkgs/linux"
@@ -85,6 +85,7 @@ source=(
   "clearlinux::git+https://github.com/clearlinux-pkgs/linux.git#tag=${_clr}"
   'enable_additional_cpu_optimizations_for_gcc_v10.1+_kernel_v5.4-5.6_v1.patch'
   'pci-enable-overrides-for-missing-acs-capabilities.patch'
+  '0001-ZEN-Add-sysctl-and-CONFIG-to-disallow-unprivileged-C.patch'
 )
 
 export KBUILD_BUILD_HOST=archlinux
@@ -115,6 +116,10 @@ prepare() {
         echo "Applying pci-enable-overrides-for-missing-acs-capabilities.patch ..."
         patch -Np1 -i "$srcdir/pci-enable-overrides-for-missing-acs-capabilities.patch"
 
+    ### disable USER_NS for non-root users by default
+        echo "Applying 0001-ZEN-Add-sysctl-and-CONFIG-to-disallow-unprivileged-C.patch ..."
+        patch -Np1 -i "$srcdir/0001-ZEN-Add-sysctl-and-CONFIG-to-disallow-unprivileged-C.patch"
+
     ### Setting config
         echo "Setting config..."
         cp -Tf $srcdir/clearlinux/config ./.config
@@ -345,7 +350,8 @@ sha256sums=('e342b04a2aa63808ea0ef1baab28fc520bd031ef8cf93d9ee4a31d4058fcb622'
             '07e737cfdc79382dc259c4844a150d8d72ebbcdc9d7e03a9503f8f8e19f1aea4'
             'SKIP'
             'c650fc6ff773e99dbc1fda9411b10b06513c5161791106c44d5a11dbcf6420f9'
-            '2c98de0814366b041aeee4cbf82b82620c7834bc33752d50f089e8bd7ea5cf5e')
+            '2c98de0814366b041aeee4cbf82b82620c7834bc33752d50f089e8bd7ea5cf5e'
+            'bdd05caf94135898bceac0a9d14ec6b1b458dba162d00efd46a292fe97f2679b')
 
 validpgpkeys=(
   'ABAF11C65A2970B130ABE3C479BE3E4300411886'  # Linus Torvalds