104 lines
3.0 KiB
Diff
104 lines
3.0 KiB
Diff
From 3a7745f6fdd71aa34dae33c3edc586363d9ece9e Mon Sep 17 00:00:00 2001
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Message-Id: <3a7745f6fdd71aa34dae33c3edc586363d9ece9e.1523790169.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 1/6] add sysctl to disallow unprivileged CLONE_NEWUSER by
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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 e5d9d405ae4e..c4be89c51f25 100644
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--- a/kernel/fork.c
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+++ b/kernel/fork.c
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@@ -103,6 +103,11 @@
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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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@@ -1591,6 +1596,10 @@ 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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@@ -2385,6 +2394,12 @@ 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 f98f28c12020..7256d339a32a 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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extern char core_pattern[];
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extern unsigned int core_pipe_limit;
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#endif
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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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extern int pid_max;
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extern int pid_max_min, pid_max_max;
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extern int percpu_pagelist_fraction;
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@@ -515,6 +518,15 @@ 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 246d4d4ce5c7..f64432b45cec 100644
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--- a/kernel/user_namespace.c
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+++ b/kernel/user_namespace.c
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@@ -26,6 +26,9 @@
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#include <linux/bsearch.h>
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#include <linux/sort.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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2.17.0
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