[bpf-next,v6,7/8] bpf: lsm: Add selftests for BPF_PROG_TYPE_LSM
diff mbox series

Message ID 20200325152629.6904-8-kpsingh@chromium.org
State New
Headers show
Series
  • MAC and Audit policy using eBPF (KRSI)
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Commit Message

KP Singh March 25, 2020, 3:26 p.m. UTC
From: KP Singh <kpsingh@google.com>

* Load/attach a BPF program that hooks to file_mprotect (int)
  and bprm_committed_creds (void).
* Perform an action that triggers the hook.
* Verify if the audit event was received using the shared global
  variables for the process executed.
* Verify if the mprotect returns a -EPERM.

Signed-off-by: KP Singh <kpsingh@google.com>
Reviewed-by: Brendan Jackman <jackmanb@google.com>
Reviewed-by: Florent Revest <revest@google.com>
Reviewed-by: Thomas Garnier <thgarnie@google.com>
---
 tools/testing/selftests/bpf/config            |  2 +
 .../selftests/bpf/prog_tests/test_lsm.c       | 84 +++++++++++++++++++
 tools/testing/selftests/bpf/progs/lsm.c       | 48 +++++++++++
 3 files changed, 134 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/test_lsm.c
 create mode 100644 tools/testing/selftests/bpf/progs/lsm.c

Comments

Andrii Nakryiko March 26, 2020, 2:01 a.m. UTC | #1
On Wed, Mar 25, 2020 at 8:27 AM KP Singh <kpsingh@chromium.org> wrote:
>
> From: KP Singh <kpsingh@google.com>
>
> * Load/attach a BPF program that hooks to file_mprotect (int)
>   and bprm_committed_creds (void).
> * Perform an action that triggers the hook.
> * Verify if the audit event was received using the shared global
>   variables for the process executed.
> * Verify if the mprotect returns a -EPERM.
>
> Signed-off-by: KP Singh <kpsingh@google.com>
> Reviewed-by: Brendan Jackman <jackmanb@google.com>
> Reviewed-by: Florent Revest <revest@google.com>
> Reviewed-by: Thomas Garnier <thgarnie@google.com>
> ---
>  tools/testing/selftests/bpf/config            |  2 +
>  .../selftests/bpf/prog_tests/test_lsm.c       | 84 +++++++++++++++++++
>  tools/testing/selftests/bpf/progs/lsm.c       | 48 +++++++++++
>  3 files changed, 134 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/test_lsm.c
>  create mode 100644 tools/testing/selftests/bpf/progs/lsm.c
>

[...]

> +
> +int exec_cmd(int *monitored_pid)
> +{
> +       int child_pid;
> +
> +       child_pid = fork();
> +       if (child_pid == 0) {
> +               *monitored_pid = getpid();
> +               execvp(CMD_ARGS[0], CMD_ARGS);
> +               return -EINVAL;
> +       } else if (child_pid > 0)

This test is part of test_progs, so let's be a good citizen and wait
for your specific child. I'd rather not hunt for elusive bugs later,
so please use waitpid() instead.

Otherwise looks good and clean, thanks!

> +               return wait(NULL);
> +
> +       return -EINVAL;
> +}
> +

[...]
KP Singh March 26, 2020, 1:36 p.m. UTC | #2
On 25-Mär 19:01, Andrii Nakryiko wrote:
> On Wed, Mar 25, 2020 at 8:27 AM KP Singh <kpsingh@chromium.org> wrote:
> >
> > From: KP Singh <kpsingh@google.com>
> >
> > * Load/attach a BPF program that hooks to file_mprotect (int)
> >   and bprm_committed_creds (void).
> > * Perform an action that triggers the hook.
> > * Verify if the audit event was received using the shared global
> >   variables for the process executed.
> > * Verify if the mprotect returns a -EPERM.
> >
> > Signed-off-by: KP Singh <kpsingh@google.com>
> > Reviewed-by: Brendan Jackman <jackmanb@google.com>
> > Reviewed-by: Florent Revest <revest@google.com>
> > Reviewed-by: Thomas Garnier <thgarnie@google.com>
> > ---
> >  tools/testing/selftests/bpf/config            |  2 +
> >  .../selftests/bpf/prog_tests/test_lsm.c       | 84 +++++++++++++++++++
> >  tools/testing/selftests/bpf/progs/lsm.c       | 48 +++++++++++
> >  3 files changed, 134 insertions(+)
> >  create mode 100644 tools/testing/selftests/bpf/prog_tests/test_lsm.c
> >  create mode 100644 tools/testing/selftests/bpf/progs/lsm.c
> >
> 
> [...]
> 
> > +
> > +int exec_cmd(int *monitored_pid)
> > +{
> > +       int child_pid;
> > +
> > +       child_pid = fork();
> > +       if (child_pid == 0) {
> > +               *monitored_pid = getpid();
> > +               execvp(CMD_ARGS[0], CMD_ARGS);
> > +               return -EINVAL;
> > +       } else if (child_pid > 0)
> 
> This test is part of test_progs, so let's be a good citizen and wait
> for your specific child. I'd rather not hunt for elusive bugs later,
> so please use waitpid() instead.

Good idea. Done.

- KP

> 
> Otherwise looks good and clean, thanks!
> 
> > +               return wait(NULL);
> > +
> > +       return -EINVAL;
> > +}
> > +
> 
> [...]

Patch
diff mbox series

diff --git a/tools/testing/selftests/bpf/config b/tools/testing/selftests/bpf/config
index 5dc109f4c097..60e3ae5d4e48 100644
--- a/tools/testing/selftests/bpf/config
+++ b/tools/testing/selftests/bpf/config
@@ -35,3 +35,5 @@  CONFIG_MPLS_ROUTING=m
 CONFIG_MPLS_IPTUNNEL=m
 CONFIG_IPV6_SIT=m
 CONFIG_BPF_JIT=y
+CONFIG_BPF_LSM=y
+CONFIG_SECURITY=y
diff --git a/tools/testing/selftests/bpf/prog_tests/test_lsm.c b/tools/testing/selftests/bpf/prog_tests/test_lsm.c
new file mode 100644
index 000000000000..eb5f5a017500
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/test_lsm.c
@@ -0,0 +1,84 @@ 
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright (C) 2020 Google LLC.
+ */
+
+#include <test_progs.h>
+#include <sys/mman.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <malloc.h>
+#include <stdlib.h>
+
+#include "lsm.skel.h"
+
+char *CMD_ARGS[] = {"true", NULL};
+
+int heap_mprotect(void)
+{
+	void *buf;
+	long sz;
+	int ret;
+
+	sz = sysconf(_SC_PAGESIZE);
+	if (sz < 0)
+		return sz;
+
+	buf = memalign(sz, 2 * sz);
+	if (buf == NULL)
+		return -ENOMEM;
+
+	ret = mprotect(buf, sz, PROT_READ | PROT_EXEC);
+	free(buf);
+	return ret;
+}
+
+int exec_cmd(int *monitored_pid)
+{
+	int child_pid;
+
+	child_pid = fork();
+	if (child_pid == 0) {
+		*monitored_pid = getpid();
+		execvp(CMD_ARGS[0], CMD_ARGS);
+		return -EINVAL;
+	} else if (child_pid > 0)
+		return wait(NULL);
+
+	return -EINVAL;
+}
+
+void test_test_lsm(void)
+{
+	struct lsm *skel = NULL;
+	int err, duration = 0;
+
+	skel = lsm__open_and_load();
+	if (CHECK(!skel, "skel_load", "lsm skeleton failed\n"))
+		goto close_prog;
+
+	err = lsm__attach(skel);
+	if (CHECK(err, "attach", "lsm attach failed: %d\n", err))
+		goto close_prog;
+
+	err = exec_cmd(&skel->bss->monitored_pid);
+	if (CHECK(err < 0, "exec_cmd", "err %d errno %d\n", err, errno))
+		goto close_prog;
+
+	CHECK(skel->bss->bprm_count != 1, "bprm_count", "bprm_count = %d",
+	      skel->bss->bprm_count);
+
+	skel->bss->monitored_pid = getpid();
+
+	err = heap_mprotect();
+	if (CHECK(errno != EPERM, "heap_mprotect", "want errno=EPERM, got %d\n",
+		  errno))
+		goto close_prog;
+
+	CHECK(skel->bss->mprotect_count != 1, "mprotect_count",
+	      "mprotect_count = %d", skel->bss->mprotect_count);
+
+close_prog:
+	lsm__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/lsm.c b/tools/testing/selftests/bpf/progs/lsm.c
new file mode 100644
index 000000000000..a4e3c223028d
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/lsm.c
@@ -0,0 +1,48 @@ 
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright 2020 Google LLC.
+ */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include  <errno.h>
+
+char _license[] SEC("license") = "GPL";
+
+int monitored_pid = 0;
+int mprotect_count = 0;
+int bprm_count = 0;
+
+SEC("lsm/file_mprotect")
+int BPF_PROG(test_int_hook, struct vm_area_struct *vma,
+	     unsigned long reqprot, unsigned long prot, int ret)
+{
+	if (ret != 0)
+		return ret;
+
+	__u32 pid = bpf_get_current_pid_tgid() >> 32;
+	int is_heap = 0;
+
+	is_heap = (vma->vm_start >= vma->vm_mm->start_brk &&
+		   vma->vm_end <= vma->vm_mm->brk);
+
+	if (is_heap && monitored_pid == pid) {
+		mprotect_count++;
+		ret = -EPERM;
+	}
+
+	return ret;
+}
+
+SEC("lsm/bprm_committed_creds")
+int BPF_PROG(test_void_hook, struct linux_binprm *bprm)
+{
+	__u32 pid = bpf_get_current_pid_tgid() >> 32;
+
+	if (monitored_pid == pid)
+		bprm_count++;
+
+	return 0;
+}