diff options
Diffstat (limited to '0001-ZEN-Add-sysctl-and-CONFIG-to-disallow-unprivileged-C.patch')
| -rw-r--r-- | 0001-ZEN-Add-sysctl-and-CONFIG-to-disallow-unprivileged-C.patch | 132 |
1 files changed, 132 insertions, 0 deletions
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..f93022e5059f --- /dev/null +++ b/0001-ZEN-Add-sysctl-and-CONFIG-to-disallow-unprivileged-C.patch @@ -0,0 +1,132 @@ +From 6136ffb3d88e9f044260f8288d2d0a1edd64379e 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 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 +@@ -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; +@@ -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); + +-- +2.23.0 + |