157 lines
4.6 KiB
Diff
157 lines
4.6 KiB
Diff
From 5ec2dd3a095442ec1a21d86042a4994f2ba24e63 Mon Sep 17 00:00:00 2001
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Message-Id: <5ec2dd3a095442ec1a21d86042a4994f2ba24e63.1512651251.git.jan.steffens@gmail.com>
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From: Serge Hallyn <serge.hallyn@canonical.com>
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Date: Fri, 31 May 2013 19:12:12 +0100
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Subject: [PATCH] add sysctl to disallow unprivileged CLONE_NEWUSER by default
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Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
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[bwh: Remove unneeded binary sysctl bits]
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Signed-off-by: Daniel Micay <danielmicay@gmail.com>
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---
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kernel/fork.c | 15 +++++++++++++++
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kernel/sysctl.c | 12 ++++++++++++
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kernel/user_namespace.c | 3 +++
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3 files changed, 30 insertions(+)
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diff --git a/kernel/fork.c b/kernel/fork.c
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index 07cc743698d3668e..4011d68a8ff9305c 100644
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--- a/kernel/fork.c
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+++ b/kernel/fork.c
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@@ -102,6 +102,11 @@
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#define CREATE_TRACE_POINTS
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#include <trace/events/task.h>
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+#ifdef CONFIG_USER_NS
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+extern int unprivileged_userns_clone;
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+#else
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+#define unprivileged_userns_clone 0
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+#endif
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/*
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* Minimum number of threads to boot the kernel
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@@ -1555,6 +1560,10 @@ static __latent_entropy struct task_struct *copy_process(
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if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS))
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return ERR_PTR(-EINVAL);
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+ if ((clone_flags & CLONE_NEWUSER) && !unprivileged_userns_clone)
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+ if (!capable(CAP_SYS_ADMIN))
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+ return ERR_PTR(-EPERM);
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+
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/*
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* Thread groups must share signals as well, and detached threads
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* can only be started up within the thread group.
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@@ -2348,6 +2357,12 @@ SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
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if (unshare_flags & CLONE_NEWNS)
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unshare_flags |= CLONE_FS;
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+ if ((unshare_flags & CLONE_NEWUSER) && !unprivileged_userns_clone) {
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+ err = -EPERM;
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+ if (!capable(CAP_SYS_ADMIN))
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+ goto bad_unshare_out;
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+ }
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+
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err = check_unshare_flags(unshare_flags);
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if (err)
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goto bad_unshare_out;
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diff --git a/kernel/sysctl.c b/kernel/sysctl.c
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index b86520ed3fb60fbf..f7dab3760839f1a1 100644
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--- a/kernel/sysctl.c
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+++ b/kernel/sysctl.c
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@@ -105,6 +105,9 @@ extern int core_uses_pid;
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#if defined(CONFIG_SYSCTL)
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+#ifdef CONFIG_USER_NS
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+extern int unprivileged_userns_clone;
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+#endif
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/* Constants used for minimum and maximum */
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#ifdef CONFIG_LOCKUP_DETECTOR
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static int sixty = 60;
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@@ -513,6 +516,15 @@ static struct ctl_table kern_table[] = {
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.proc_handler = proc_dointvec,
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},
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#endif
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+#ifdef CONFIG_USER_NS
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+ {
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+ .procname = "unprivileged_userns_clone",
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+ .data = &unprivileged_userns_clone,
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+ .maxlen = sizeof(int),
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+ .mode = 0644,
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+ .proc_handler = proc_dointvec,
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+ },
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+#endif
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#ifdef CONFIG_PROC_SYSCTL
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{
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.procname = "tainted",
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diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
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index c490f1e4313b998a..dd03bd39d7bf194d 100644
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--- a/kernel/user_namespace.c
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+++ b/kernel/user_namespace.c
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@@ -24,6 +24,9 @@
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#include <linux/projid.h>
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#include <linux/fs_struct.h>
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+/* sysctl */
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+int unprivileged_userns_clone;
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+
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static struct kmem_cache *user_ns_cachep __read_mostly;
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static DEFINE_MUTEX(userns_state_mutex);
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--
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2.15.1
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From b5202296055dd333db4425120d3f93ef4e6a0573 Mon Sep 17 00:00:00 2001
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From: "Jan Alexander Steffens (heftig)" <jan.steffens@gmail.com>
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Date: Thu, 7 Dec 2017 13:50:48 +0100
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Subject: ZEN: Add CONFIG for unprivileged_userns_clone
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This way our default behavior continues to match the vanilla kernel.
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---
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init/Kconfig | 16 ++++++++++++++++
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kernel/user_namespace.c | 4 ++++
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2 files changed, 20 insertions(+)
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diff --git a/init/Kconfig b/init/Kconfig
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index 4592bf7997c0..f3df02990aff 100644
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--- a/init/Kconfig
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+++ b/init/Kconfig
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@@ -1004,6 +1004,22 @@ config USER_NS
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If unsure, say N.
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+config USER_NS_UNPRIVILEGED
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+ bool "Allow unprivileged users to create namespaces"
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+ default y
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+ depends on USER_NS
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+ help
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+ When disabled, unprivileged users will not be able to create
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+ new namespaces. Allowing users to create their own namespaces
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+ has been part of several recent local privilege escalation
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+ exploits, so if you need user namespaces but are
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+ paranoid^Wsecurity-conscious you want to disable this.
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+
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+ This setting can be overridden at runtime via the
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+ kernel.unprivileged_userns_clone sysctl.
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+
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+ If unsure, say Y.
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+
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config PID_NS
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bool "PID Namespaces"
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default y
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diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
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index 6b9dbc257e34..107b17f0d528 100644
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--- a/kernel/user_namespace.c
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+++ b/kernel/user_namespace.c
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@@ -27,7 +27,11 @@
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#include <linux/sort.h>
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/* sysctl */
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+#ifdef CONFIG_USER_NS_UNPRIVILEGED
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+int unprivileged_userns_clone = 1;
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+#else
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int unprivileged_userns_clone;
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+#endif
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static struct kmem_cache *user_ns_cachep __read_mostly;
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static DEFINE_MUTEX(userns_state_mutex);
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