selftests/bpf: Add tests for restricted helpers

This patch adds tests that bpf_ktime_get_coarse_ns(), bpf_timer_* and
bpf_spin_lock()/bpf_spin_unlock() helpers are forbidden in tracing progs
as their use there may result in various locking issues.

Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211113142227.566439-3-me@ubique.spb.ru

tools/testing/selftests/bpf/prog_tests/helper_restricted.c

@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <test_progs.h>
+#include "test_helper_restricted.skel.h"
+
+void test_helper_restricted(void)
+{
+	int prog_i = 0, prog_cnt;
+	int duration = 0;
+
+	do {
+		struct test_helper_restricted *test;
+		int maybeOK;
+
+		test = test_helper_restricted__open();
+		if (!ASSERT_OK_PTR(test, "open"))
+			return;
+
+		prog_cnt = test->skeleton->prog_cnt;
+
+		for (int j = 0; j < prog_cnt; ++j) {
+			struct bpf_program *prog = *test->skeleton->progs[j].prog;
+
+			maybeOK = bpf_program__set_autoload(prog, prog_i == j);
+			ASSERT_OK(maybeOK, "set autoload");
+		}
+
+		maybeOK = test_helper_restricted__load(test);
+		CHECK(!maybeOK, test->skeleton->progs[prog_i].name, "helper isn't restricted");
+
+		test_helper_restricted__destroy(test);
+	} while (++prog_i < prog_cnt);
+}

tools/testing/selftests/bpf/progs/test_helper_restricted.c

@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <time.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+struct timer {
+	struct bpf_timer t;
+};
+
+struct lock {
+	struct bpf_spin_lock l;
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, struct timer);
+} timers SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, struct lock);
+} locks SEC(".maps");
+
+static int timer_cb(void *map, int *key, struct timer *timer)
+{
+	return 0;
+}
+
+static void timer_work(void)
+{
+	struct timer *timer;
+	const int key = 0;
+
+	timer  = bpf_map_lookup_elem(&timers, &key);
+	if (timer) {
+		bpf_timer_init(&timer->t, &timers, CLOCK_MONOTONIC);
+		bpf_timer_set_callback(&timer->t, timer_cb);
+		bpf_timer_start(&timer->t, 10E9, 0);
+		bpf_timer_cancel(&timer->t);
+	}
+}
+
+static void spin_lock_work(void)
+{
+	const int key = 0;
+	struct lock *lock;
+
+	lock = bpf_map_lookup_elem(&locks, &key);
+	if (lock) {
+		bpf_spin_lock(&lock->l);
+		bpf_spin_unlock(&lock->l);
+	}
+}
+
+SEC("raw_tp/sys_enter")
+int raw_tp_timer(void *ctx)
+{
+	timer_work();
+
+	return 0;
+}
+
+SEC("tp/syscalls/sys_enter_nanosleep")
+int tp_timer(void *ctx)
+{
+	timer_work();
+
+	return 0;
+}
+
+SEC("kprobe/sys_nanosleep")
+int kprobe_timer(void *ctx)
+{
+	timer_work();
+
+	return 0;
+}
+
+SEC("perf_event")
+int perf_event_timer(void *ctx)
+{
+	timer_work();
+
+	return 0;
+}
+
+SEC("raw_tp/sys_enter")
+int raw_tp_spin_lock(void *ctx)
+{
+	spin_lock_work();
+
+	return 0;
+}
+
+SEC("tp/syscalls/sys_enter_nanosleep")
+int tp_spin_lock(void *ctx)
+{
+	spin_lock_work();
+
+	return 0;
+}
+
+SEC("kprobe/sys_nanosleep")
+int kprobe_spin_lock(void *ctx)
+{
+	spin_lock_work();
+
+	return 0;
+}
+
+SEC("perf_event")
+int perf_event_spin_lock(void *ctx)
+{
+	spin_lock_work();
+
+	return 0;
+}
+
+const char LICENSE[] SEC("license") = "GPL";

tools/testing/selftests/bpf/test_verifier.c

@@ -92,6 +92,7 @@ struct bpf_test {
 	int fixup_map_event_output[MAX_FIXUPS];
 	int fixup_map_reuseport_array[MAX_FIXUPS];
 	int fixup_map_ringbuf[MAX_FIXUPS];
+	int fixup_map_timer[MAX_FIXUPS];
 	/* Expected verifier log output for result REJECT or VERBOSE_ACCEPT.
 	 * Can be a tab-separated sequence of expected strings. An empty string
 	 * means no log verification.
@@ -604,8 +605,15 @@ static int create_cgroup_storage(bool percpu)
  *   int cnt;
  *   struct bpf_spin_lock l;
  * };
+ * struct bpf_timer {
+ *   __u64 :64;
+ *   __u64 :64;
+ * } __attribute__((aligned(8)));
+ * struct timer {
+ *   struct bpf_timer t;
+ * };
  */
-static const char btf_str_sec[] = "\0bpf_spin_lock\0val\0cnt\0l";
+static const char btf_str_sec[] = "\0bpf_spin_lock\0val\0cnt\0l\0bpf_timer\0timer\0t";
 static __u32 btf_raw_types[] = {
 	/* int */
 	BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),  /* [1] */
@@ -616,6 +624,11 @@ static __u32 btf_raw_types[] = {
 	BTF_TYPE_ENC(15, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 8),
 	BTF_MEMBER_ENC(19, 1, 0), /* int cnt; */
 	BTF_MEMBER_ENC(23, 2, 32),/* struct bpf_spin_lock l; */
+	/* struct bpf_timer */                          /* [4] */
+	BTF_TYPE_ENC(25, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 0), 16),
+	/* struct timer */                              /* [5] */
+	BTF_TYPE_ENC(35, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 1), 16),
+	BTF_MEMBER_ENC(41, 4, 0), /* struct bpf_timer t; */
 };
 
 static int load_btf(void)
@@ -696,6 +709,29 @@ static int create_sk_storage_map(void)
 	return fd;
 }
 
+static int create_map_timer(void)
+{
+	struct bpf_create_map_attr attr = {
+		.name = "test_map",
+		.map_type = BPF_MAP_TYPE_ARRAY,
+		.key_size = 4,
+		.value_size = 16,
+		.max_entries = 1,
+		.btf_key_type_id = 1,
+		.btf_value_type_id = 5,
+	};
+	int fd, btf_fd;
+
+	btf_fd = load_btf();
+	if (btf_fd < 0)
+		return -1;
+	attr.btf_fd = btf_fd;
+	fd = bpf_create_map_xattr(&attr);
+	if (fd < 0)
+		printf("Failed to create map with timer\n");
+	return fd;
+}
+
 static char bpf_vlog[UINT_MAX >> 8];
 
 static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
@@ -722,6 +758,7 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
 	int *fixup_map_event_output = test->fixup_map_event_output;
 	int *fixup_map_reuseport_array = test->fixup_map_reuseport_array;
 	int *fixup_map_ringbuf = test->fixup_map_ringbuf;
+	int *fixup_map_timer = test->fixup_map_timer;
 
 	if (test->fill_helper) {
 		test->fill_insns = calloc(MAX_TEST_INSNS, sizeof(struct bpf_insn));
@@ -907,6 +944,13 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
 			fixup_map_ringbuf++;
 		} while (*fixup_map_ringbuf);
 	}
+	if (*fixup_map_timer) {
+		map_fds[21] = create_map_timer();
+		do {
+			prog[*fixup_map_timer].imm = map_fds[21];
+			fixup_map_timer++;
+		} while (*fixup_map_timer);
+	}
 }
 
 struct libcap {

tools/testing/selftests/bpf/verifier/helper_restricted.c

@@ -0,0 +1,196 @@
+{
+	"bpf_ktime_get_coarse_ns is forbidden in BPF_PROG_TYPE_KPROBE",
+	.insns = {
+		BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ktime_get_coarse_ns),
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	},
+	.errstr = "unknown func bpf_ktime_get_coarse_ns",
+	.result = REJECT,
+	.prog_type = BPF_PROG_TYPE_KPROBE,
+},
+{
+	"bpf_ktime_get_coarse_ns is forbidden in BPF_PROG_TYPE_TRACEPOINT",
+	.insns = {
+		BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ktime_get_coarse_ns),
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	},
+	.errstr = "unknown func bpf_ktime_get_coarse_ns",
+	.result = REJECT,
+	.prog_type = BPF_PROG_TYPE_TRACEPOINT,
+},
+{
+	"bpf_ktime_get_coarse_ns is forbidden in BPF_PROG_TYPE_PERF_EVENT",
+	.insns = {
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ktime_get_coarse_ns),
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.errstr = "unknown func bpf_ktime_get_coarse_ns",
+	.result = REJECT,
+	.prog_type = BPF_PROG_TYPE_PERF_EVENT,
+},
+{
+	"bpf_ktime_get_coarse_ns is forbidden in BPF_PROG_TYPE_RAW_TRACEPOINT",
+	.insns = {
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ktime_get_coarse_ns),
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.errstr = "unknown func bpf_ktime_get_coarse_ns",
+	.result = REJECT,
+	.prog_type = BPF_PROG_TYPE_RAW_TRACEPOINT,
+},
+{
+	"bpf_timer_init isn restricted in BPF_PROG_TYPE_KPROBE",
+	.insns = {
+	BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+	BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),
+	BPF_LD_MAP_FD(BPF_REG_1, 0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+	BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 4),
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+	BPF_LD_MAP_FD(BPF_REG_2, 0),
+	BPF_MOV64_IMM(BPF_REG_3, 1),
+	BPF_EMIT_CALL(BPF_FUNC_timer_init),
+	BPF_EXIT_INSN(),
+	},
+	.fixup_map_timer = { 3, 8 },
+	.errstr = "tracing progs cannot use bpf_timer yet",
+	.result = REJECT,
+	.prog_type = BPF_PROG_TYPE_KPROBE,
+},
+{
+	"bpf_timer_init is forbidden in BPF_PROG_TYPE_PERF_EVENT",
+	.insns = {
+	BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+	BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),
+	BPF_LD_MAP_FD(BPF_REG_1, 0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+	BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 4),
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+	BPF_LD_MAP_FD(BPF_REG_2, 0),
+	BPF_MOV64_IMM(BPF_REG_3, 1),
+	BPF_EMIT_CALL(BPF_FUNC_timer_init),
+	BPF_EXIT_INSN(),
+	},
+	.fixup_map_timer = { 3, 8 },
+	.errstr = "tracing progs cannot use bpf_timer yet",
+	.result = REJECT,
+	.prog_type = BPF_PROG_TYPE_PERF_EVENT,
+},
+{
+	"bpf_timer_init is forbidden in BPF_PROG_TYPE_TRACEPOINT",
+	.insns = {
+	BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+	BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),
+	BPF_LD_MAP_FD(BPF_REG_1, 0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+	BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 4),
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+	BPF_LD_MAP_FD(BPF_REG_2, 0),
+	BPF_MOV64_IMM(BPF_REG_3, 1),
+	BPF_EMIT_CALL(BPF_FUNC_timer_init),
+	BPF_EXIT_INSN(),
+	},
+	.fixup_map_timer = { 3, 8 },
+	.errstr = "tracing progs cannot use bpf_timer yet",
+	.result = REJECT,
+	.prog_type = BPF_PROG_TYPE_TRACEPOINT,
+},
+{
+	"bpf_timer_init is forbidden in BPF_PROG_TYPE_RAW_TRACEPOINT",
+	.insns = {
+	BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+	BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),
+	BPF_LD_MAP_FD(BPF_REG_1, 0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+	BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 4),
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+	BPF_LD_MAP_FD(BPF_REG_2, 0),
+	BPF_MOV64_IMM(BPF_REG_3, 1),
+	BPF_EMIT_CALL(BPF_FUNC_timer_init),
+	BPF_EXIT_INSN(),
+	},
+	.fixup_map_timer = { 3, 8 },
+	.errstr = "tracing progs cannot use bpf_timer yet",
+	.result = REJECT,
+	.prog_type = BPF_PROG_TYPE_RAW_TRACEPOINT,
+},
+{
+	"bpf_spin_lock is forbidden in BPF_PROG_TYPE_KPROBE",
+	.insns = {
+	BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+	BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),
+	BPF_LD_MAP_FD(BPF_REG_1, 0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+	BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+	BPF_EMIT_CALL(BPF_FUNC_spin_lock),
+	BPF_EXIT_INSN(),
+	},
+	.fixup_map_spin_lock = { 3 },
+	.errstr = "tracing progs cannot use bpf_spin_lock yet",
+	.result = REJECT,
+	.prog_type = BPF_PROG_TYPE_KPROBE,
+},
+{
+	"bpf_spin_lock is forbidden in BPF_PROG_TYPE_TRACEPOINT",
+	.insns = {
+	BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+	BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),
+	BPF_LD_MAP_FD(BPF_REG_1, 0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+	BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+	BPF_EMIT_CALL(BPF_FUNC_spin_lock),
+	BPF_EXIT_INSN(),
+	},
+	.fixup_map_spin_lock = { 3 },
+	.errstr = "tracing progs cannot use bpf_spin_lock yet",
+	.result = REJECT,
+	.prog_type = BPF_PROG_TYPE_TRACEPOINT,
+},
+{
+	"bpf_spin_lock is forbidden in BPF_PROG_TYPE_PERF_EVENT",
+	.insns = {
+	BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+	BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),
+	BPF_LD_MAP_FD(BPF_REG_1, 0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+	BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+	BPF_EMIT_CALL(BPF_FUNC_spin_lock),
+	BPF_EXIT_INSN(),
+	},
+	.fixup_map_spin_lock = { 3 },
+	.errstr = "tracing progs cannot use bpf_spin_lock yet",
+	.result = REJECT,
+	.prog_type = BPF_PROG_TYPE_PERF_EVENT,
+},
+{
+	"bpf_spin_lock is forbidden in BPF_PROG_TYPE_RAW_TRACEPOINT",
+	.insns = {
+	BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+	BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),
+	BPF_LD_MAP_FD(BPF_REG_1, 0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+	BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+	BPF_EMIT_CALL(BPF_FUNC_spin_lock),
+	BPF_EXIT_INSN(),
+	},
+	.fixup_map_spin_lock = { 3 },
+	.errstr = "tracing progs cannot use bpf_spin_lock yet",
+	.result = REJECT,
+	.prog_type = BPF_PROG_TYPE_RAW_TRACEPOINT,
+},