selftests/bpf: verifier/prevent_map_lookup converted to inline assembly

Test verifier/prevent_map_lookup automatically converted to use inline assembly.

This was a part of a series [1] but could not be applied becuase
another patch from a series had to be witheld.

[1] https://lore.kernel.org/bpf/20230421174234.2391278-1-eddyz87@gmail.com/

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20230421204514.2450907-1-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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

@@ -42,6 +42,7 @@
 #include "verifier_meta_access.skel.h"
 #include "verifier_netfilter_ctx.skel.h"
 #include "verifier_netfilter_retcode.skel.h"
+#include "verifier_prevent_map_lookup.skel.h"
 #include "verifier_raw_stack.skel.h"
 #include "verifier_raw_tp_writable.skel.h"
 #include "verifier_reg_equal.skel.h"
@@ -140,6 +141,7 @@ void test_verifier_masking(void)              { RUN(verifier_masking); }
 void test_verifier_meta_access(void)          { RUN(verifier_meta_access); }
 void test_verifier_netfilter_ctx(void)        { RUN(verifier_netfilter_ctx); }
 void test_verifier_netfilter_retcode(void)    { RUN(verifier_netfilter_retcode); }
+void test_verifier_prevent_map_lookup(void)   { RUN(verifier_prevent_map_lookup); }
 void test_verifier_raw_stack(void)            { RUN(verifier_raw_stack); }
 void test_verifier_raw_tp_writable(void)      { RUN(verifier_raw_tp_writable); }
 void test_verifier_reg_equal(void)            { RUN(verifier_reg_equal); }

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

@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Converted from tools/testing/selftests/bpf/verifier/prevent_map_lookup.c */
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+struct {
+	__uint(type, BPF_MAP_TYPE_STACK_TRACE);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, __u64);
+} map_stacktrace SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_PROG_ARRAY);
+	__uint(max_entries, 8);
+	__uint(key_size, sizeof(int));
+	__array(values, void (void));
+} map_prog2_socket SEC(".maps");
+
+SEC("perf_event")
+__description("prevent map lookup in stack trace")
+__failure __msg("cannot pass map_type 7 into func bpf_map_lookup_elem")
+__naked void map_lookup_in_stack_trace(void)
+{
+	asm volatile ("					\
+	r1 = 0;						\
+	*(u64*)(r10 - 8) = r1;				\
+	r2 = r10;					\
+	r2 += -8;					\
+	r1 = %[map_stacktrace] ll;			\
+	call %[bpf_map_lookup_elem];			\
+	exit;						\
+"	:
+	: __imm(bpf_map_lookup_elem),
+	  __imm_addr(map_stacktrace)
+	: __clobber_all);
+}
+
+SEC("socket")
+__description("prevent map lookup in prog array")
+__failure __msg("cannot pass map_type 3 into func bpf_map_lookup_elem")
+__failure_unpriv
+__naked void map_lookup_in_prog_array(void)
+{
+	asm volatile ("					\
+	r1 = 0;						\
+	*(u64*)(r10 - 8) = r1;				\
+	r2 = r10;					\
+	r2 += -8;					\
+	r1 = %[map_prog2_socket] ll;			\
+	call %[bpf_map_lookup_elem];			\
+	exit;						\
+"	:
+	: __imm(bpf_map_lookup_elem),
+	  __imm_addr(map_prog2_socket)
+	: __clobber_all);
+}
+
+char _license[] SEC("license") = "GPL";