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Message-Id: <20160914072415.26021-20-mic@digikod.net>
Date: Wed, 14 Sep 2016 09:24:12 +0200
From: Mickaël Salaün <mic@...ikod.net>
To: linux-kernel@...r.kernel.org
Cc: Mickaël Salaün <mic@...ikod.net>,
Alexei Starovoitov <ast@...nel.org>,
Andy Lutomirski <luto@...capital.net>, Arnd Bergmann <arnd@...db.de>,
Casey Schaufler <casey@...aufler-ca.com>,
Daniel Borkmann <daniel@...earbox.net>,
Daniel Mack <daniel@...que.org>, David Drysdale <drysdale@...gle.com>,
"David S . Miller" <davem@...emloft.net>,
Elena Reshetova <elena.reshetova@...el.com>,
"Eric W . Biederman" <ebiederm@...ssion.com>,
James Morris <james.l.morris@...cle.com>,
Kees Cook <keescook@...omium.org>, Paul Moore <pmoore@...hat.com>,
Sargun Dhillon <sargun@...gun.me>,
"Serge E . Hallyn" <serge@...lyn.com>, Tejun Heo <tj@...nel.org>,
Will Drewry <wad@...omium.org>, kernel-hardening@...ts.openwall.com,
linux-api@...r.kernel.org, linux-security-module@...r.kernel.org,
netdev@...r.kernel.org, cgroups@...r.kernel.org
Subject: [RFC v3 19/22] landlock: Add interrupted origin
This third origin of hook call should cover all possible trigger paths
(e.g. page fault). Landlock eBPF programs can then take decisions
accordingly.
Signed-off-by: Mickaël Salaün <mic@...ikod.net>
Cc: Alexei Starovoitov <ast@...nel.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Daniel Borkmann <daniel@...earbox.net>
Cc: Kees Cook <keescook@...omium.org>
---
include/uapi/linux/bpf.h | 3 ++-
security/landlock/lsm.c | 17 +++++++++++++++--
2 files changed, 17 insertions(+), 3 deletions(-)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 12e61508f879..3cc52e51357f 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -580,7 +580,8 @@ enum landlock_hook_id {
/* Trigger type */
#define LANDLOCK_FLAG_ORIGIN_SYSCALL (1 << 0)
#define LANDLOCK_FLAG_ORIGIN_SECCOMP (1 << 1)
-#define _LANDLOCK_FLAG_ORIGIN_MASK ((1 << 2) - 1)
+#define LANDLOCK_FLAG_ORIGIN_INTERRUPT (1 << 2)
+#define _LANDLOCK_FLAG_ORIGIN_MASK ((1 << 3) - 1)
/* context of function access flags */
#define _LANDLOCK_FLAG_ACCESS_MASK ((1ULL << 0) - 1)
diff --git a/security/landlock/lsm.c b/security/landlock/lsm.c
index 000dd0c7ec3d..2a15839a08c8 100644
--- a/security/landlock/lsm.c
+++ b/security/landlock/lsm.c
@@ -17,6 +17,7 @@
#include <linux/kernel.h> /* FIELD_SIZEOF() */
#include <linux/landlock.h>
#include <linux/lsm_hooks.h>
+#include <linux/preempt.h> /* in_interrupt() */
#include <linux/seccomp.h> /* struct seccomp_* */
#include <linux/types.h> /* uintptr_t */
@@ -109,6 +110,7 @@ static int landlock_run_prog(enum landlock_hook_id hook_id, __u64 args[6])
#endif /* CONFIG_CGROUP_BPF */
struct landlock_rule *rule;
u32 hook_idx = get_index(hook_id);
+ u16 current_call;
struct landlock_data ctx = {
.hook = hook_id,
@@ -128,6 +130,16 @@ static int landlock_run_prog(enum landlock_hook_id hook_id, __u64 args[6])
* prioritize fine-grained policies (i.e. per thread), and return early.
*/
+ if (unlikely(in_interrupt())) {
+ current_call = LANDLOCK_FLAG_ORIGIN_INTERRUPT;
+#ifdef CONFIG_SECCOMP_FILTER
+ /* bypass landlock_ret evaluation */
+ goto seccomp_int;
+#endif /* CONFIG_SECCOMP_FILTER */
+ } else {
+ current_call = LANDLOCK_FLAG_ORIGIN_SYSCALL;
+ }
+
#ifdef CONFIG_SECCOMP_FILTER
/* seccomp triggers and landlock_ret cleanup */
ctx.origin = LANDLOCK_FLAG_ORIGIN_SECCOMP;
@@ -164,8 +176,9 @@ static int landlock_run_prog(enum landlock_hook_id hook_id, __u64 args[6])
return -ret;
ctx.cookie = 0;
+seccomp_int:
/* syscall trigger */
- ctx.origin = LANDLOCK_FLAG_ORIGIN_SYSCALL;
+ ctx.origin = current_call;
ret = landlock_run_prog_for_syscall(hook_idx, &ctx,
current->seccomp.landlock_hooks);
if (ret)
@@ -175,7 +188,7 @@ static int landlock_run_prog(enum landlock_hook_id hook_id, __u64 args[6])
#ifdef CONFIG_CGROUP_BPF
/* syscall trigger */
if (cgroup_bpf_enabled) {
- ctx.origin = LANDLOCK_FLAG_ORIGIN_SYSCALL;
+ ctx.origin = current_call;
/* get the default cgroup associated with the current thread */
cgrp = task_css_set(current)->dfl_cgrp;
ret = landlock_run_prog_for_syscall(hook_idx, &ctx,
--
2.9.3
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