linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
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

  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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20170328234650.19695-8-mic@digikod.net \
    --to=mic@digikod.net \
    --cc=acme@kernel.org \
    --cc=ast@kernel.org \
    --cc=casey@schaufler-ca.com \
    --cc=corbet@lwn.net \
    --cc=daniel@iogearbox.net \
    --cc=davem@davemloft.net \
    --cc=drysdale@google.com \
    --cc=ebiederm@xmission.com \
    --cc=james.l.morris@oracle.com \
    --cc=jann@thejh.net \
    --cc=keescook@chromium.org \
    --cc=kernel-hardening@lists.openwall.com \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-security-module@vger.kernel.org \
    --cc=luto@amacapital.net \
    --cc=mjg59@srcf.ucam.org \
    --cc=mtk.manpages@gmail.com \
    --cc=netdev@vger.kernel.org \
    --cc=paul@paul-moore.com \
    --cc=sargun@sargun.me \
    --cc=serge@hallyn.com \
    --cc=shuah@kernel.org \
    --cc=tgraf@suug.ch \
    --cc=tj@kernel.org \
    --cc=wad@chromium.org \
    --subject='Re: [PATCH net-next v6 07/11] landlock: Add ptrace restrictions' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).