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-rw-r--r--0001-ZEN-Add-sysctl-and-CONFIG-to-disallow-unprivileged-CLONE_NEWUSER.patch122
1 files changed, 122 insertions, 0 deletions
diff --git a/0001-ZEN-Add-sysctl-and-CONFIG-to-disallow-unprivileged-CLONE_NEWUSER.patch b/0001-ZEN-Add-sysctl-and-CONFIG-to-disallow-unprivileged-CLONE_NEWUSER.patch
new file mode 100644
index 00000000000..5301464f63c
--- /dev/null
+++ b/0001-ZEN-Add-sysctl-and-CONFIG-to-disallow-unprivileged-CLONE_NEWUSER.patch
@@ -0,0 +1,122 @@
+--- a/include/linux/sysctl.h 2020-06-12 19:27:22.382363840 +0200
++++ b/include/linux/sysctl.h 2020-06-12 19:27:04.715697333 +0200
+@@ -204,6 +204,10 @@ extern int unaligned_enabled;
+ extern int unaligned_dump_stack;
+ extern int no_unaligned_warning;
+
++#ifdef CONFIG_USER_NS
++extern int unprivileged_userns_clone;
++#endif
++
+ extern struct ctl_table sysctl_mount_point[];
+ extern struct ctl_table random_table[];
+ extern struct ctl_table firmware_config_table[];
+
+diff --git a/init/Kconfig b/init/Kconfig
+index bd7d650d4a99..658f9c052151 100644
+--- a/init/Kconfig
++++ b/init/Kconfig
+@@ -1091,6 +1091,22 @@ 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 541fd805fb88..ffd57c812153 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
+@@ -1788,6 +1793,10 @@ 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.
+@@ -2819,6 +2828,12 @@ 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 078950d9605b..baead3605bbe 100644
+--- a/kernel/sysctl.c
++++ b/kernel/sysctl.c
+@@ -545,6 +548,15 @@ 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);
+
+--
+cgit v1.2.1-1-g437b
+