bpf: selftests: Add selftests for module kfunc support
This adds selftests that tests the success and failure path for modules
kfuncs (in presence of invalid kfunc calls) for both libbpf and
gen_loader. It also adds a prog_test kfunc_btf_id_list so that we can
add module BTF ID set from bpf_testmod.
This also introduces a couple of test cases to verifier selftests for
validating whether we get an error or not depending on if invalid kfunc
call remains after elimination of unreachable instructions.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211002011757.311265-10-memxor@gmail.com
diff --git a/include/linux/btf.h b/include/linux/btf.h
index 1d56cd2..203eef99 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -275,5 +275,6 @@
THIS_MODULE }
extern struct kfunc_btf_id_list bpf_tcp_ca_kfunc_list;
+extern struct kfunc_btf_id_list prog_test_kfunc_list;
#endif
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 1460dff..2ebffb9 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -6397,3 +6397,4 @@
EXPORT_SYMBOL_GPL(name)
DEFINE_KFUNC_BTF_ID_LIST(bpf_tcp_ca_kfunc_list);
+DEFINE_KFUNC_BTF_ID_LIST(prog_test_kfunc_list);
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index b1f6f52..5296087 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -2,6 +2,7 @@
/* Copyright (c) 2017 Facebook
*/
#include <linux/bpf.h>
+#include <linux/btf.h>
#include <linux/btf_ids.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
@@ -243,7 +244,9 @@
bool bpf_prog_test_check_kfunc_call(u32 kfunc_id, struct module *owner)
{
- return btf_id_set_contains(&test_sk_kfunc_ids, kfunc_id);
+ if (btf_id_set_contains(&test_sk_kfunc_ids, kfunc_id))
+ return true;
+ return bpf_check_mod_kfunc_call(&prog_test_kfunc_list, kfunc_id, owner);
}
static void *bpf_test_init(const union bpf_attr *kattr, u32 size,
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 5a94d09..c5c9a9f 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -315,8 +315,9 @@
linked_vars.skel.h linked_maps.skel.h
LSKELS := kfunc_call_test.c fentry_test.c fexit_test.c fexit_sleep.c \
- test_ksyms_module.c test_ringbuf.c atomics.c trace_printk.c \
- trace_vprintk.c
+ test_ringbuf.c atomics.c trace_printk.c trace_vprintk.c
+# Generate both light skeleton and libbpf skeleton for these
+LSKELS_EXTRA := test_ksyms_module.c
SKEL_BLACKLIST += $$(LSKELS)
test_static_linked.skel.h-deps := test_static_linked1.o test_static_linked2.o
@@ -346,7 +347,7 @@
TRUNNER_BPF_SKELS := $$(patsubst %.c,$$(TRUNNER_OUTPUT)/%.skel.h, \
$$(filter-out $(SKEL_BLACKLIST) $(LINKED_BPF_SRCS),\
$$(TRUNNER_BPF_SRCS)))
-TRUNNER_BPF_LSKELS := $$(patsubst %.c,$$(TRUNNER_OUTPUT)/%.lskel.h, $$(LSKELS))
+TRUNNER_BPF_LSKELS := $$(patsubst %.c,$$(TRUNNER_OUTPUT)/%.lskel.h, $$(LSKELS) $$(LSKELS_EXTRA))
TRUNNER_BPF_SKELS_LINKED := $$(addprefix $$(TRUNNER_OUTPUT)/,$(LINKED_SKELS))
TEST_GEN_FILES += $$(TRUNNER_BPF_OBJS)
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
index 50fc556..b892948 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
@@ -1,5 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2020 Facebook */
+#include <linux/btf.h>
+#include <linux/btf_ids.h>
#include <linux/error-injection.h>
#include <linux/init.h>
#include <linux/module.h>
@@ -13,6 +15,12 @@
DEFINE_PER_CPU(int, bpf_testmod_ksym_percpu) = 123;
+noinline void
+bpf_testmod_test_mod_kfunc(int i)
+{
+ *(int *)this_cpu_ptr(&bpf_testmod_ksym_percpu) = i;
+}
+
noinline int bpf_testmod_loop_test(int n)
{
int i, sum = 0;
@@ -71,13 +79,26 @@
.write = bpf_testmod_test_write,
};
+BTF_SET_START(bpf_testmod_kfunc_ids)
+BTF_ID(func, bpf_testmod_test_mod_kfunc)
+BTF_SET_END(bpf_testmod_kfunc_ids)
+
+static DEFINE_KFUNC_BTF_ID_SET(&bpf_testmod_kfunc_ids, bpf_testmod_kfunc_btf_set);
+
static int bpf_testmod_init(void)
{
- return sysfs_create_bin_file(kernel_kobj, &bin_attr_bpf_testmod_file);
+ int ret;
+
+ ret = sysfs_create_bin_file(kernel_kobj, &bin_attr_bpf_testmod_file);
+ if (ret)
+ return ret;
+ register_kfunc_btf_id_set(&prog_test_kfunc_list, &bpf_testmod_kfunc_btf_set);
+ return 0;
}
static void bpf_testmod_exit(void)
{
+ unregister_kfunc_btf_id_set(&prog_test_kfunc_list, &bpf_testmod_kfunc_btf_set);
return sysfs_remove_bin_file(kernel_kobj, &bin_attr_bpf_testmod_file);
}
diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms_module.c b/tools/testing/selftests/bpf/prog_tests/ksyms_module.c
index 2cd5cde..8314478 100644
--- a/tools/testing/selftests/bpf/prog_tests/ksyms_module.c
+++ b/tools/testing/selftests/bpf/prog_tests/ksyms_module.c
@@ -2,30 +2,29 @@
/* Copyright (c) 2021 Facebook */
#include <test_progs.h>
-#include <bpf/libbpf.h>
-#include <bpf/btf.h>
+#include <network_helpers.h>
#include "test_ksyms_module.lskel.h"
-static int duration;
-
void test_ksyms_module(void)
{
- struct test_ksyms_module* skel;
+ struct test_ksyms_module *skel;
+ int retval;
int err;
- skel = test_ksyms_module__open_and_load();
- if (CHECK(!skel, "skel_open", "failed to open skeleton\n"))
+ if (!env.has_testmod) {
+ test__skip();
return;
+ }
- err = test_ksyms_module__attach(skel);
- if (CHECK(err, "skel_attach", "skeleton attach failed: %d\n", err))
+ skel = test_ksyms_module__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "test_ksyms_module__open_and_load"))
+ return;
+ err = bpf_prog_test_run(skel->progs.load.prog_fd, 1, &pkt_v4, sizeof(pkt_v4),
+ NULL, NULL, (__u32 *)&retval, NULL);
+ if (!ASSERT_OK(err, "bpf_prog_test_run"))
goto cleanup;
-
- usleep(1);
-
- ASSERT_EQ(skel->bss->triggered, true, "triggered");
- ASSERT_EQ(skel->bss->out_mod_ksym_global, 123, "global_ksym_val");
-
+ ASSERT_EQ(retval, 0, "retval");
+ ASSERT_EQ(skel->bss->out_bpf_testmod_ksym, 42, "bpf_testmod_ksym");
cleanup:
test_ksyms_module__destroy(skel);
}
diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms_module_libbpf.c b/tools/testing/selftests/bpf/prog_tests/ksyms_module_libbpf.c
new file mode 100644
index 0000000..e6343ef
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/ksyms_module_libbpf.c
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <test_progs.h>
+#include <network_helpers.h>
+#include "test_ksyms_module.skel.h"
+
+void test_ksyms_module_libbpf(void)
+{
+ struct test_ksyms_module *skel;
+ int retval, err;
+
+ if (!env.has_testmod) {
+ test__skip();
+ return;
+ }
+
+ skel = test_ksyms_module__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "test_ksyms_module__open"))
+ return;
+ err = bpf_prog_test_run(bpf_program__fd(skel->progs.load), 1, &pkt_v4,
+ sizeof(pkt_v4), NULL, NULL, (__u32 *)&retval, NULL);
+ if (!ASSERT_OK(err, "bpf_prog_test_run"))
+ goto cleanup;
+ ASSERT_EQ(retval, 0, "retval");
+ ASSERT_EQ(skel->bss->out_bpf_testmod_ksym, 42, "bpf_testmod_ksym");
+cleanup:
+ test_ksyms_module__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_ksyms_module.c b/tools/testing/selftests/bpf/progs/test_ksyms_module.c
index d6a0b30..0650d91 100644
--- a/tools/testing/selftests/bpf/progs/test_ksyms_module.c
+++ b/tools/testing/selftests/bpf/progs/test_ksyms_module.c
@@ -2,24 +2,48 @@
/* Copyright (c) 2021 Facebook */
#include "vmlinux.h"
-
#include <bpf/bpf_helpers.h>
+#define X_0(x)
+#define X_1(x) x X_0(x)
+#define X_2(x) x X_1(x)
+#define X_3(x) x X_2(x)
+#define X_4(x) x X_3(x)
+#define X_5(x) x X_4(x)
+#define X_6(x) x X_5(x)
+#define X_7(x) x X_6(x)
+#define X_8(x) x X_7(x)
+#define X_9(x) x X_8(x)
+#define X_10(x) x X_9(x)
+#define REPEAT_256(Y) X_2(X_10(X_10(Y))) X_5(X_10(Y)) X_6(Y)
+
extern const int bpf_testmod_ksym_percpu __ksym;
+extern void bpf_testmod_test_mod_kfunc(int i) __ksym;
+extern void bpf_testmod_invalid_mod_kfunc(void) __ksym __weak;
-int out_mod_ksym_global = 0;
-bool triggered = false;
+int out_bpf_testmod_ksym = 0;
+const volatile int x = 0;
-SEC("raw_tp/sys_enter")
-int handler(const void *ctx)
+SEC("tc")
+int load(struct __sk_buff *skb)
{
- int *val;
- __u32 cpu;
+ /* This will be kept by clang, but removed by verifier. Since it is
+ * marked as __weak, libbpf and gen_loader don't error out if BTF ID
+ * is not found for it, instead imm and off is set to 0 for it.
+ */
+ if (x)
+ bpf_testmod_invalid_mod_kfunc();
+ bpf_testmod_test_mod_kfunc(42);
+ out_bpf_testmod_ksym = *(int *)bpf_this_cpu_ptr(&bpf_testmod_ksym_percpu);
+ return 0;
+}
- val = (int *)bpf_this_cpu_ptr(&bpf_testmod_ksym_percpu);
- out_mod_ksym_global = *val;
- triggered = true;
-
+SEC("tc")
+int load_256(struct __sk_buff *skb)
+{
+ /* this will fail if kfunc doesn't reuse its own btf fd index */
+ REPEAT_256(bpf_testmod_test_mod_kfunc(42););
+ bpf_testmod_test_mod_kfunc(42);
return 0;
}
diff --git a/tools/testing/selftests/bpf/verifier/calls.c b/tools/testing/selftests/bpf/verifier/calls.c
index 336a749..d7b74eb 100644
--- a/tools/testing/selftests/bpf/verifier/calls.c
+++ b/tools/testing/selftests/bpf/verifier/calls.c
@@ -1,4 +1,27 @@
{
+ "calls: invalid kfunc call not eliminated",
+ .insns = {
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+ BPF_MOV64_IMM(BPF_REG_0, 1),
+ BPF_EXIT_INSN(),
+ },
+ .prog_type = BPF_PROG_TYPE_TRACEPOINT,
+ .result = REJECT,
+ .errstr = "invalid kernel function call not eliminated in verifier pass",
+},
+{
+ "calls: invalid kfunc call unreachable",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_0, 1),
+ BPF_JMP_IMM(BPF_JGT, BPF_REG_0, 0, 2),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+ BPF_MOV64_IMM(BPF_REG_0, 1),
+ BPF_EXIT_INSN(),
+ },
+ .prog_type = BPF_PROG_TYPE_TRACEPOINT,
+ .result = ACCEPT,
+},
+{
"calls: basic sanity",
.insns = {
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 2),
