From: "Mickaël Salaün" <mic@digikod.net>
To: linux-kernel@vger.kernel.org
Cc: "Mickaël Salaün" <mic@digikod.net>,
"Alexei Starovoitov" <ast@kernel.org>,
"Andy Lutomirski" <luto@amacapital.net>,
"Arnaldo Carvalho de Melo" <acme@kernel.org>,
"Casey Schaufler" <casey@schaufler-ca.com>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"David Drysdale" <drysdale@google.com>,
"David S . Miller" <davem@davemloft.net>,
"Eric W . Biederman" <ebiederm@xmission.com>,
"James Morris" <james.l.morris@oracle.com>,
"Jann Horn" <jann@thejh.net>, "Jonathan Corbet" <corbet@lwn.net>,
"Matthew Garrett" <mjg59@srcf.ucam.org>,
"Michael Kerrisk" <mtk.manpages@gmail.com>,
"Kees Cook" <keescook@chromium.org>,
"Paul Moore" <paul@paul-moore.com>,
"Sargun Dhillon" <sargun@sargun.me>,
"Serge E . Hallyn" <serge@hallyn.com>,
"Shuah Khan" <shuah@kernel.org>, "Tejun Heo" <tj@kernel.org>,
"Thomas Graf" <tgraf@suug.ch>, "Will Drewry" <wad@chromium.org>,
kernel-hardening@lists.openwall.com, linux-api@vger.kernel.org,
linux-security-module@vger.kernel.org, netdev@vger.kernel.org
Subject: [PATCH net-next v6 07/11] landlock: Add ptrace restrictions
Date: Wed, 29 Mar 2017 01:46:46 +0200 [thread overview]
Message-ID: <20170328234650.19695-8-mic@digikod.net> (raw)
In-Reply-To: <20170328234650.19695-1-mic@digikod.net>
A landlocked process has less privileges than a non-landlocked process
and must then be subject to additional restrictions when manipulating
processes. To be allowed to use ptrace(2) and related syscalls on a
target process, a landlocked process must have a subset of the target
process' rules.
New in v6
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: James Morris <james.l.morris@oracle.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Serge E. Hallyn <serge@hallyn.com>
---
security/landlock/Makefile | 2 +-
security/landlock/hooks_ptrace.c | 126 +++++++++++++++++++++++++++++++++++++++
security/landlock/hooks_ptrace.h | 11 ++++
security/landlock/init.c | 2 +
4 files changed, 140 insertions(+), 1 deletion(-)
create mode 100644 security/landlock/hooks_ptrace.c
create mode 100644 security/landlock/hooks_ptrace.h
diff --git a/security/landlock/Makefile b/security/landlock/Makefile
index da8ba8b5183e..099a56ca4842 100644
--- a/security/landlock/Makefile
+++ b/security/landlock/Makefile
@@ -2,4 +2,4 @@ ccflags-$(CONFIG_SECURITY_LANDLOCK) += -Werror=unused-function
obj-$(CONFIG_SECURITY_LANDLOCK) := landlock.o
-landlock-y := init.o providers.o hooks.o hooks_fs.o
+landlock-y := init.o providers.o hooks.o hooks_fs.o hooks_ptrace.o
diff --git a/security/landlock/hooks_ptrace.c b/security/landlock/hooks_ptrace.c
new file mode 100644
index 000000000000..8ab53baba9ad
--- /dev/null
+++ b/security/landlock/hooks_ptrace.c
@@ -0,0 +1,126 @@
+/*
+ * Landlock LSM - ptrace hooks
+ *
+ * Copyright © 2017 Mickaël Salaün <mic@digikod.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ */
+
+#include <asm/current.h>
+#include <linux/kernel.h> /* ARRAY_SIZE */
+#include <linux/landlock.h> /* struct landlock_events */
+#include <linux/lsm_hooks.h>
+#include <linux/sched.h> /* struct task_struct */
+#include <linux/seccomp.h>
+
+#include "hooks.h" /* landlocked() */
+
+#include "hooks_ptrace.h"
+
+
+static bool landlock_events_are_subset(const struct landlock_events *parent,
+ const struct landlock_events *child)
+{
+ size_t i;
+
+ if (!parent || !child)
+ return false;
+ if (parent == child)
+ return true;
+
+ for (i = 0; i < ARRAY_SIZE(child->rules); i++) {
+ struct landlock_rule *walker;
+ bool found_parent = false;
+
+ if (!parent->rules[i])
+ continue;
+ for (walker = child->rules[i]; walker; walker = walker->prev) {
+ if (walker == parent->rules[i]) {
+ found_parent = true;
+ break;
+ }
+ }
+ if (!found_parent)
+ return false;
+ }
+ return true;
+}
+
+static bool landlock_task_has_subset_events(const struct task_struct *parent,
+ const struct task_struct *child)
+{
+#ifdef CONFIG_SECCOMP_FILTER
+ if (landlock_events_are_subset(parent->seccomp.landlock_events,
+ child->seccomp.landlock_events))
+ /* must be ANDed with other providers (i.e. cgroup) */
+ return true;
+#endif /* CONFIG_SECCOMP_FILTER */
+ return false;
+}
+
+/**
+ * landlock_ptrace_access_check - determine whether the current process may
+ * access another
+ *
+ * @child: the process to be accessed
+ * @mode: the mode of attachment
+ *
+ * If the current task has Landlock rules, then the child must have at least
+ * the same rules. Else denied.
+ *
+ * Determine whether a process may access another, returning 0 if permission
+ * granted, -errno if denied.
+ */
+static int landlock_ptrace_access_check(struct task_struct *child,
+ unsigned int mode)
+{
+ if (!landlocked(current))
+ return 0;
+
+ if (!landlocked(child))
+ return -EPERM;
+
+ if (landlock_task_has_subset_events(current, child))
+ return 0;
+
+ return -EPERM;
+}
+
+/**
+ * landlock_ptrace_traceme - determine whether another process may trace the
+ * current one
+ *
+ * @parent: the task proposed to be the tracer
+ *
+ * If the parent has Landlock rules, then the current task must have the same
+ * or more rules.
+ * Else denied.
+ *
+ * Determine whether the nominated task is permitted to trace the current
+ * process, returning 0 if permission is granted, -errno if denied.
+ */
+static int landlock_ptrace_traceme(struct task_struct *parent)
+{
+ if (!landlocked(parent))
+ return 0;
+
+ if (!landlocked(current))
+ return -EPERM;
+
+ if (landlock_task_has_subset_events(parent, current))
+ return 0;
+
+ return -EPERM;
+}
+
+static struct security_hook_list landlock_hooks[] = {
+ LSM_HOOK_INIT(ptrace_access_check, landlock_ptrace_access_check),
+ LSM_HOOK_INIT(ptrace_traceme, landlock_ptrace_traceme),
+};
+
+__init void landlock_add_hooks_ptrace(void)
+{
+ landlock_register_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks));
+}
diff --git a/security/landlock/hooks_ptrace.h b/security/landlock/hooks_ptrace.h
new file mode 100644
index 000000000000..15b1f3479e0e
--- /dev/null
+++ b/security/landlock/hooks_ptrace.h
@@ -0,0 +1,11 @@
+/*
+ * Landlock LSM - ptrace hooks
+ *
+ * Copyright © 2017 Mickaël Salaün <mic@digikod.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ */
+
+__init void landlock_add_hooks_ptrace(void);
diff --git a/security/landlock/init.c b/security/landlock/init.c
index ef8a3da69860..c8bce3142a32 100644
--- a/security/landlock/init.c
+++ b/security/landlock/init.c
@@ -14,6 +14,7 @@
#include <linux/lsm_hooks.h>
#include "hooks_fs.h"
+#include "hooks_ptrace.h"
static inline bool bpf_landlock_is_valid_access(int off, int size,
@@ -137,6 +138,7 @@ void __init landlock_add_hooks(void)
{
pr_info("landlock: Version %u, ready to sandbox with %s\n",
LANDLOCK_VERSION, "seccomp");
+ landlock_add_hooks_ptrace();
landlock_add_hooks_fs();
security_add_hooks(NULL, 0, "landlock");
bpf_register_prog_type(&bpf_landlock_type);
--
2.11.0
next prev parent reply other threads:[~2017-03-28 23:48 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-28 23:46 [PATCH net-next v6 00/11] Landlock LSM: Toward unprivileged sandboxing Mickaël Salaün
2017-03-28 23:46 ` [PATCH net-next v6 01/11] bpf: Add eBPF program subtype and is_valid_subtype() verifier Mickaël Salaün
2017-03-29 13:48 ` kbuild test robot
2017-04-18 21:48 ` Kees Cook
2017-03-28 23:46 ` [PATCH net-next v6 02/11] bpf,landlock: Define an eBPF program type for Landlock Mickaël Salaün
2017-04-16 21:57 ` Mickaël Salaün
2017-04-18 21:58 ` Kees Cook
2017-03-28 23:46 ` [PATCH net-next v6 03/11] bpf: Define handle_fs and add a new helper bpf_handle_fs_get_mode() Mickaël Salaün
2017-03-28 23:46 ` [PATCH net-next v6 04/11] landlock: Add LSM hooks related to filesystem Mickaël Salaün
2017-03-29 15:18 ` kbuild test robot
2017-04-18 22:17 ` Kees Cook
2017-04-18 22:44 ` Mickaël Salaün
2017-04-18 23:16 ` Casey Schaufler
2017-04-18 23:40 ` Kees Cook
2017-04-19 22:03 ` Mickaël Salaün
2017-04-19 23:58 ` [kernel-hardening] " Casey Schaufler
2017-04-20 1:48 ` Kees Cook
2017-04-18 23:39 ` Kees Cook
2017-03-28 23:46 ` [PATCH net-next v6 05/11] seccomp: Split put_seccomp_filter() with put_seccomp() Mickaël Salaün
2017-04-18 22:23 ` Kees Cook
2017-04-18 22:47 ` Mickaël Salaün
2017-04-19 22:18 ` Mickaël Salaün
2017-04-20 1:54 ` Kees Cook
2017-03-28 23:46 ` [PATCH net-next v6 06/11] seccomp,landlock: Handle Landlock events per process hierarchy Mickaël Salaün
2017-03-29 10:35 ` [kernel-hardening] " Djalal Harouni
2017-03-31 21:15 ` Mickaël Salaün
2017-04-18 22:54 ` Kees Cook
2017-04-18 22:53 ` Kees Cook
2017-04-18 23:24 ` Mickaël Salaün
2017-04-18 23:48 ` Kees Cook
2017-03-28 23:46 ` Mickaël Salaün [this message]
2017-04-10 6:48 ` [kernel-hardening] [PATCH net-next v6 07/11] landlock: Add ptrace restrictions Djalal Harouni
2017-04-11 7:19 ` Mickaël Salaün
2017-03-28 23:46 ` [PATCH net-next v6 08/11] bpf: Add a Landlock sandbox example Mickaël Salaün
2017-04-18 23:06 ` Kees Cook
2017-04-18 23:35 ` Mickaël Salaün
2017-03-28 23:46 ` [PATCH net-next v6 09/11] seccomp: Enhance test_harness with an assert step mechanism Mickaël Salaün
2017-04-19 0:02 ` Kees Cook
2017-04-19 21:51 ` Mickaël Salaün
2017-04-19 22:02 ` Kees Cook
2017-04-19 22:05 ` Mickaël Salaün
2017-04-20 1:50 ` Kees Cook
2017-03-28 23:46 ` [PATCH net-next v6 10/11] bpf,landlock: Add tests for Landlock Mickaël Salaün
2017-04-18 23:16 ` Kees Cook
2017-04-18 23:53 ` Mickaël Salaün
2017-04-18 23:59 ` Kees Cook
2017-03-28 23:46 ` [PATCH net-next v6 11/11] landlock: Add user and kernel documentation " Mickaël Salaün
2017-03-29 15:58 ` kbuild test robot
2017-04-18 23:26 ` [PATCH net-next v6 00/11] Landlock LSM: Toward unprivileged sandboxing Kees Cook
2017-04-19 0:12 ` Mickaël Salaün
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