Contributors: 3
Author Tokens Token Proportion Commits Commit Proportion
Kumar Kartikeya Dwivedi 1556 70.22% 5 55.56%
Eduard Zingerman 443 19.99% 1 11.11%
Paul Chaignon 217 9.79% 3 33.33%
Total 2216 9 


// SPDX-License-Identifier: GPL-2.0
/* Converted from tools/testing/selftests/bpf/verifier/ctx.c */

#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
#include "bpf_misc.h"
#include "../test_kmods/bpf_testmod_kfunc.h"

static const char ctx_strncmp_target[] = "ctx";
static const char ctx_snprintf_fmt[] = "";

SEC("tc")
__description("context stores via BPF_ATOMIC")
__failure __msg("BPF_ATOMIC stores into R1 ctx is not allowed")
__naked void context_stores_via_bpf_atomic(void)
{
	asm volatile ("					\
	r0 = 0;						\
	lock *(u32 *)(r1 + %[__sk_buff_mark]) += w0;	\
	exit;						\
"	:
	: __imm_const(__sk_buff_mark, offsetof(struct __sk_buff, mark))
	: __clobber_all);
}

SEC("tc")
__description("arithmetic ops make PTR_TO_CTX unusable")
__failure __msg("dereference of modified ctx ptr")
__naked void make_ptr_to_ctx_unusable(void)
{
	asm volatile ("					\
	r1 += %[__imm_0];				\
	r0 = *(u32*)(r1 + %[__sk_buff_mark]);		\
	exit;						\
"	:
	: __imm_const(__imm_0,
		      offsetof(struct __sk_buff, data) - offsetof(struct __sk_buff, mark)),
	  __imm_const(__sk_buff_mark, offsetof(struct __sk_buff, mark))
	: __clobber_all);
}

SEC("tc")
__description("pass unmodified ctx pointer to helper")
__success __retval(0)
__naked void unmodified_ctx_pointer_to_helper(void)
{
	asm volatile ("					\
	r2 = 0;						\
	call %[bpf_csum_update];			\
	r0 = 0;						\
	exit;						\
"	:
	: __imm(bpf_csum_update)
	: __clobber_all);
}

SEC("tc")
__description("pass modified ctx pointer to helper, 1")
__failure __msg("negative offset ctx ptr R1 off=-612 disallowed")
__naked void ctx_pointer_to_helper_1(void)
{
	asm volatile ("					\
	r1 += -612;					\
	r2 = 0;						\
	call %[bpf_csum_update];			\
	r0 = 0;						\
	exit;						\
"	:
	: __imm(bpf_csum_update)
	: __clobber_all);
}

SEC("socket")
__description("pass modified ctx pointer to helper, 2")
__failure __msg("negative offset ctx ptr R1 off=-612 disallowed")
__naked void ctx_pointer_to_helper_2(void)
{
	asm volatile ("					\
	r1 += -612;					\
	call %[bpf_get_socket_cookie];			\
	r0 = 0;						\
	exit;						\
"	:
	: __imm(bpf_get_socket_cookie)
	: __clobber_all);
}

SEC("tc")
__description("pass modified ctx pointer to helper, 3")
__failure __msg("variable ctx access var_off=(0x0; 0x4)")
__naked void ctx_pointer_to_helper_3(void)
{
	asm volatile ("					\
	r3 = *(u32*)(r1 + 0);				\
	r3 &= 4;					\
	r1 += r3;					\
	r2 = 0;						\
	call %[bpf_csum_update];			\
	r0 = 0;						\
	exit;						\
"	:
	: __imm(bpf_csum_update)
	: __clobber_all);
}

SEC("cgroup/sendmsg6")
__description("pass ctx or null check, 1: ctx")
__success
__naked void or_null_check_1_ctx(void)
{
	asm volatile ("					\
	call %[bpf_get_netns_cookie];			\
	r0 = 0;						\
	exit;						\
"	:
	: __imm(bpf_get_netns_cookie)
	: __clobber_all);
}

SEC("cgroup/sendmsg6")
__description("pass ctx or null check, 2: null")
__success
__naked void or_null_check_2_null(void)
{
	asm volatile ("					\
	r1 = 0;						\
	call %[bpf_get_netns_cookie];			\
	r0 = 0;						\
	exit;						\
"	:
	: __imm(bpf_get_netns_cookie)
	: __clobber_all);
}

SEC("cgroup/sendmsg6")
__description("pass ctx or null check, 3: 1")
__failure __msg("R1 type=scalar expected=ctx")
__naked void or_null_check_3_1(void)
{
	asm volatile ("					\
	r1 = 1;						\
	call %[bpf_get_netns_cookie];			\
	r0 = 0;						\
	exit;						\
"	:
	: __imm(bpf_get_netns_cookie)
	: __clobber_all);
}

SEC("cgroup/sendmsg6")
__description("pass ctx or null check, 4: ctx - const")
__failure __msg("negative offset ctx ptr R1 off=-612 disallowed")
__naked void null_check_4_ctx_const(void)
{
	asm volatile ("					\
	r1 += -612;					\
	call %[bpf_get_netns_cookie];			\
	r0 = 0;						\
	exit;						\
"	:
	: __imm(bpf_get_netns_cookie)
	: __clobber_all);
}

SEC("cgroup/connect4")
__description("pass ctx or null check, 5: null (connect)")
__success
__naked void null_check_5_null_connect(void)
{
	asm volatile ("					\
	r1 = 0;						\
	call %[bpf_get_netns_cookie];			\
	r0 = 0;						\
	exit;						\
"	:
	: __imm(bpf_get_netns_cookie)
	: __clobber_all);
}

SEC("cgroup/post_bind4")
__description("pass ctx or null check, 6: null (bind)")
__success
__naked void null_check_6_null_bind(void)
{
	asm volatile ("					\
	r1 = 0;						\
	call %[bpf_get_netns_cookie];			\
	r0 = 0;						\
	exit;						\
"	:
	: __imm(bpf_get_netns_cookie)
	: __clobber_all);
}

SEC("cgroup/post_bind4")
__description("pass ctx or null check, 7: ctx (bind)")
__success
__naked void null_check_7_ctx_bind(void)
{
	asm volatile ("					\
	call %[bpf_get_socket_cookie];			\
	r0 = 0;						\
	exit;						\
"	:
	: __imm(bpf_get_socket_cookie)
	: __clobber_all);
}

SEC("cgroup/post_bind4")
__description("pass ctx or null check, 8: null (bind)")
__failure __msg("R1 type=scalar expected=ctx")
__naked void null_check_8_null_bind(void)
{
	asm volatile ("					\
	r1 = 0;						\
	call %[bpf_get_socket_cookie];			\
	r0 = 0;						\
	exit;						\
"	:
	: __imm(bpf_get_socket_cookie)
	: __clobber_all);
}

#define narrow_load(type, ctx, field)					\
	SEC(type)							\
	__description("narrow load on field " #field " of " #ctx)	\
	__failure __msg("invalid bpf_context access")			\
	__naked void invalid_narrow_load##ctx##field(void)		\
	{								\
		asm volatile ("						\
		r1 = *(u32 *)(r1 + %[off]);				\
		r0 = 0;							\
		exit;"							\
		:							\
		: __imm_const(off, offsetof(struct ctx, field) + 4)	\
		: __clobber_all);					\
	}

narrow_load("cgroup/getsockopt", bpf_sockopt, sk);
narrow_load("cgroup/getsockopt", bpf_sockopt, optval);
narrow_load("cgroup/getsockopt", bpf_sockopt, optval_end);
narrow_load("tc", __sk_buff, sk);
narrow_load("cgroup/bind4", bpf_sock_addr, sk);
narrow_load("sockops", bpf_sock_ops, sk);
narrow_load("sockops", bpf_sock_ops, skb_data);
narrow_load("sockops", bpf_sock_ops, skb_data_end);
narrow_load("sockops", bpf_sock_ops, skb_hwtstamp);

#define unaligned_access(type, ctx, field)					\
	SEC(type)								\
	__description("unaligned access on field " #field " of " #ctx)		\
	__failure __msg("invalid bpf_context access")				\
	__naked void unaligned_ctx_access_##ctx##field(void)			\
	{									\
		asm volatile ("							\
		r1 = *(u%[size] *)(r1 + %[off]);				\
		r0 = 0;								\
		exit;"								\
		:								\
		: __imm_const(size, sizeof_field(struct ctx, field) * 8),	\
		  __imm_const(off, offsetof(struct ctx, field) + 1)		\
		: __clobber_all);						\
	}

unaligned_access("flow_dissector", __sk_buff, data);
unaligned_access("netfilter", bpf_nf_ctx, skb);

#define padding_access(type, ctx, prev_field, sz)			\
	SEC(type)							\
	__description("access on " #ctx " padding after " #prev_field)	\
	__naked void padding_ctx_access_##ctx(void)			\
	{								\
		asm volatile ("						\
		r1 = *(u%[size] *)(r1 + %[off]);			\
		r0 = 0;							\
		exit;"							\
		:							\
		: __imm_const(size, sz * 8),				\
		  __imm_const(off, offsetofend(struct ctx, prev_field))	\
		: __clobber_all);					\
	}

__failure __msg("invalid bpf_context access")
padding_access("cgroup/bind4", bpf_sock_addr, msg_src_ip6[3], 4);

__success
padding_access("sk_lookup", bpf_sk_lookup, remote_port, 2);

__failure __msg("invalid bpf_context access")
padding_access("tc", __sk_buff, tstamp_type, 2);

__failure __msg("invalid bpf_context access")
padding_access("cgroup/post_bind4", bpf_sock, dst_port, 2);

__failure __msg("invalid bpf_context access")
padding_access("sk_reuseport", sk_reuseport_md, hash, 4);

SEC("?syscall")
__description("syscall: write to ctx with fixed offset")
__success
int syscall_ctx_fixed_off_write(void *ctx)
{
	char *p = ctx;

	*(__u32 *)p = 0;
	*(__u32 *)(p + 4) = 0;
	return 0;
}

SEC("?syscall")
__description("syscall: read ctx with fixed offset")
__success
int syscall_ctx_fixed_off_read(void *ctx)
{
	char *p = ctx;
	volatile __u32 val;

	val = *(__u32 *)(p + 4);
	(void)val;
	return 0;
}

SEC("?syscall")
__description("syscall: unaligned read ctx with fixed offset")
__success
int syscall_ctx_unaligned_fixed_off_read(void *ctx)
{
	char *p = ctx;
	volatile __u32 val;

	val = *(__u32 *)(p + 2);
	(void)val;
	return 0;
}

SEC("?syscall")
__description("syscall: unaligned write ctx with fixed offset")
__success
int syscall_ctx_unaligned_fixed_off_write(void *ctx)
{
	char *p = ctx;

	*(__u32 *)(p + 2) = 0;
	return 0;
}

SEC("?syscall")
__description("syscall: read ctx with variable offset")
__success
int syscall_ctx_var_off_read(void *ctx)
{
	__u64 off = bpf_get_prandom_u32();
	char *p = ctx;
	volatile __u32 val;

	off &= 0xfc;
	p += off;
	val = *(__u32 *)p;
	(void)val;
	return 0;
}

SEC("?syscall")
__description("syscall: write ctx with variable offset")
__success
int syscall_ctx_var_off_write(void *ctx)
{
	__u64 off = bpf_get_prandom_u32();
	char *p = ctx;

	off &= 0xfc;
	p += off;
	*(__u32 *)p = 0;
	return 0;
}

SEC("?syscall")
__description("syscall: unaligned read ctx with variable offset")
__success
int syscall_ctx_unaligned_var_off_read(void *ctx)
{
	__u64 off = bpf_get_prandom_u32();
	char *p = ctx;
	volatile __u32 val;

	off &= 0xfc;
	off += 2;
	p += off;
	val = *(__u32 *)p;
	(void)val;
	return 0;
}

SEC("?syscall")
__description("syscall: unaligned write ctx with variable offset")
__success
int syscall_ctx_unaligned_var_off_write(void *ctx)
{
	__u64 off = bpf_get_prandom_u32();
	char *p = ctx;

	off &= 0xfc;
	off += 2;
	p += off;
	*(__u32 *)p = 0;
	return 0;
}

SEC("?syscall")
__description("syscall: reject ctx access past U16_MAX with fixed offset")
__failure __msg("outside of the allowed memory range")
int syscall_ctx_u16_max_fixed_off(void *ctx)
{
	char *p = ctx;
	volatile __u32 val;

	p += 65535;
	val = *(__u32 *)p;
	(void)val;
	return 0;
}

SEC("?syscall")
__description("syscall: reject ctx access past U16_MAX with variable offset")
__failure __msg("outside of the allowed memory range")
int syscall_ctx_u16_max_var_off(void *ctx)
{
	__u64 off = bpf_get_prandom_u32();
	char *p = ctx;
	volatile __u32 val;

	off &= 0xffff;
	off += 1;
	p += off;
	val = *(__u32 *)p;
	(void)val;
	return 0;
}

SEC("?syscall")
__description("syscall: reject negative variable offset ctx access")
__failure __msg("min value is negative")
int syscall_ctx_neg_var_off(void *ctx)
{
	__u64 off = bpf_get_prandom_u32();
	char *p = ctx;

	off &= 4;
	p -= off;
	return *(__u32 *)p;
}

SEC("?syscall")
__description("syscall: reject unbounded variable offset ctx access")
__failure __msg("unbounded memory access")
int syscall_ctx_unbounded_var_off(void *ctx)
{
	__u64 off = (__u32)bpf_get_prandom_u32();
	char *p = ctx;

	off <<= 2;
	p += off;
	return *(__u32 *)p;
}

SEC("?syscall")
__description("syscall: helper read ctx with fixed offset")
__success
int syscall_ctx_helper_fixed_off_read(void *ctx)
{
	char *p = ctx;

	p += 4;
	return bpf_strncmp(p, 4, ctx_strncmp_target);
}

SEC("?syscall")
__description("syscall: helper write ctx with fixed offset")
__success
int syscall_ctx_helper_fixed_off_write(void *ctx)
{
	char *p = ctx;

	p += 4;
	return bpf_probe_read_kernel(p, 4, 0);
}

SEC("?syscall")
__description("syscall: helper unaligned read ctx with fixed offset")
__success
int syscall_ctx_helper_unaligned_fixed_off_read(void *ctx)
{
	char *p = ctx;

	p += 2;
	return bpf_strncmp(p, 4, ctx_strncmp_target);
}

SEC("?syscall")
__description("syscall: helper unaligned write ctx with fixed offset")
__success
int syscall_ctx_helper_unaligned_fixed_off_write(void *ctx)
{
	char *p = ctx;

	p += 2;
	return bpf_probe_read_kernel(p, 4, 0);
}

SEC("?syscall")
__description("syscall: helper read ctx with variable offset")
__success
int syscall_ctx_helper_var_off_read(void *ctx)
{
	__u64 off = bpf_get_prandom_u32();
	char *p = ctx;

	off &= 0xfc;
	p += off;
	return bpf_strncmp(p, 4, ctx_strncmp_target);
}

SEC("?syscall")
__description("syscall: helper write ctx with variable offset")
__success
int syscall_ctx_helper_var_off_write(void *ctx)
{
	__u64 off = bpf_get_prandom_u32();
	char *p = ctx;

	off &= 0xfc;
	p += off;
	return bpf_probe_read_kernel(p, 4, 0);
}

SEC("?syscall")
__description("syscall: helper unaligned read ctx with variable offset")
__success
int syscall_ctx_helper_unaligned_var_off_read(void *ctx)
{
	__u64 off = bpf_get_prandom_u32();
	char *p = ctx;

	off &= 0xfc;
	off += 2;
	p += off;
	return bpf_strncmp(p, 4, ctx_strncmp_target);
}

SEC("?syscall")
__description("syscall: helper unaligned write ctx with variable offset")
__success
int syscall_ctx_helper_unaligned_var_off_write(void *ctx)
{
	__u64 off = bpf_get_prandom_u32();
	char *p = ctx;

	off &= 0xfc;
	off += 2;
	p += off;
	return bpf_probe_read_kernel(p, 4, 0);
}

SEC("?syscall")
__description("syscall: reject helper read ctx past U16_MAX with fixed offset")
__failure __msg("outside of the allowed memory range")
int syscall_ctx_helper_u16_max_fixed_off_read(void *ctx)
{
	char *p = ctx;

	p += 65535;
	return bpf_strncmp(p, 4, ctx_strncmp_target);
}

SEC("?syscall")
__description("syscall: reject helper write ctx past U16_MAX with fixed offset")
__failure __msg("outside of the allowed memory range")
int syscall_ctx_helper_u16_max_fixed_off_write(void *ctx)
{
	char *p = ctx;

	p += 65535;
	return bpf_probe_read_kernel(p, 4, 0);
}

SEC("?syscall")
__description("syscall: reject helper read ctx past U16_MAX with variable offset")
__failure __msg("outside of the allowed memory range")
int syscall_ctx_helper_u16_max_var_off_read(void *ctx)
{
	__u64 off = bpf_get_prandom_u32();
	char *p = ctx;

	off &= 0xffff;
	off += 1;
	p += off;
	return bpf_strncmp(p, 4, ctx_strncmp_target);
}

SEC("?syscall")
__description("syscall: reject helper write ctx past U16_MAX with variable offset")
__failure __msg("outside of the allowed memory range")
int syscall_ctx_helper_u16_max_var_off_write(void *ctx)
{
	__u64 off = bpf_get_prandom_u32();
	char *p = ctx;

	off &= 0xffff;
	off += 1;
	p += off;
	return bpf_probe_read_kernel(p, 4, 0);
}

SEC("?syscall")
__description("syscall: helper read zero-sized ctx access")
__success
int syscall_ctx_helper_zero_sized_read(void *ctx)
{
	return bpf_snprintf(0, 0, ctx_snprintf_fmt, ctx, 0);
}

SEC("?syscall")
__description("syscall: helper write zero-sized ctx access")
__success
int syscall_ctx_helper_zero_sized_write(void *ctx)
{
	return bpf_probe_read_kernel(ctx, 0, 0);
}

SEC("?syscall")
__description("syscall: kfunc access ctx with fixed offset")
__success
int syscall_ctx_kfunc_fixed_off(void *ctx)
{
	char *p = ctx;

	p += 4;
	bpf_kfunc_call_test_mem_len_pass1(p, 4);
	return 0;
}

SEC("?syscall")
__description("syscall: kfunc access ctx with variable offset")
__success
int syscall_ctx_kfunc_var_off(void *ctx)
{
	__u64 off = bpf_get_prandom_u32();
	char *p = ctx;

	off &= 0xfc;
	p += off;
	bpf_kfunc_call_test_mem_len_pass1(p, 4);
	return 0;
}

SEC("?syscall")
__description("syscall: kfunc unaligned access ctx with fixed offset")
__success
int syscall_ctx_kfunc_unaligned_fixed_off(void *ctx)
{
	char *p = ctx;

	p += 2;
	bpf_kfunc_call_test_mem_len_pass1(p, 4);
	return 0;
}

SEC("?syscall")
__description("syscall: kfunc unaligned access ctx with variable offset")
__success
int syscall_ctx_kfunc_unaligned_var_off(void *ctx)
{
	__u64 off = bpf_get_prandom_u32();
	char *p = ctx;

	off &= 0xfc;
	off += 2;
	p += off;
	bpf_kfunc_call_test_mem_len_pass1(p, 4);
	return 0;
}

SEC("?syscall")
__description("syscall: reject kfunc ctx access past U16_MAX with fixed offset")
__failure __msg("outside of the allowed memory range")
int syscall_ctx_kfunc_u16_max_fixed_off(void *ctx)
{
	char *p = ctx;

	p += 65535;
	bpf_kfunc_call_test_mem_len_pass1(p, 4);
	return 0;
}

SEC("?syscall")
__description("syscall: reject kfunc ctx access past U16_MAX with variable offset")
__failure __msg("outside of the allowed memory range")
int syscall_ctx_kfunc_u16_max_var_off(void *ctx)
{
	__u64 off = bpf_get_prandom_u32();
	char *p = ctx;

	off &= 0xffff;
	off += 1;
	p += off;
	bpf_kfunc_call_test_mem_len_pass1(p, 4);
	return 0;
}

SEC("?syscall")
__description("syscall: kfunc access zero-sized ctx")
__success
int syscall_ctx_kfunc_zero_sized(void *ctx)
{
	bpf_kfunc_call_test_mem_len_pass1(ctx, 0);
	return 0;
}

/*
 * For non-syscall program types without convert_ctx_access, direct ctx
 * dereference is still allowed after adding a fixed offset, while variable
 * and negative direct accesses reject.
 *
 * Passing ctx as a helper or kfunc memory argument is only permitted for
 * syscall programs, so the helper and kfunc cases below validate rejection
 * for non-syscall ctx pointers at fixed, variable, and zero-sized accesses.
 */
#define no_rewrite_ctx_access(type, name, off, load_t)			\
	SEC("?" type)							\
	__description(type ": read ctx at fixed offset")		\
	__success							\
	int no_rewrite_##name##_fixed(void *ctx)			\
	{								\
		char *p = ctx;						\
		volatile load_t val;					\
									\
		val = *(load_t *)(p + off);				\
		(void)val;						\
		return 0;						\
	}								\
	SEC("?" type)							\
	__description(type ": reject variable offset ctx access")	\
	__failure __msg("variable ctx access var_off=")			\
	int no_rewrite_##name##_var(void *ctx)			\
	{								\
		__u64 off_var = bpf_get_prandom_u32();			\
		char *p = ctx;						\
									\
		off_var &= 4;						\
		p += off_var;						\
		return *(load_t *)p;					\
	}								\
	SEC("?" type)							\
	__description(type ": reject negative offset ctx access")	\
	__failure __msg("invalid bpf_context access")			\
	int no_rewrite_##name##_neg(void *ctx)			\
	{								\
		char *p = ctx;						\
									\
		p -= 612;						\
		return *(load_t *)p;					\
	}								\
	SEC("?" type)							\
	__description(type ": reject helper read ctx at fixed offset")	\
	__failure __msg("dereference of modified ctx ptr")		\
	int no_rewrite_##name##_helper_read_fixed(void *ctx)		\
	{								\
		char *p = ctx;						\
									\
		p += off;						\
		return bpf_strncmp(p, 4, ctx_strncmp_target);		\
	}								\
	SEC("?" type)							\
	__description(type ": reject helper write ctx at fixed offset")	\
	__failure __msg("dereference of modified ctx ptr")		\
	int no_rewrite_##name##_helper_write_fixed(void *ctx)		\
	{								\
		char *p = ctx;						\
									\
		p += off;						\
		return bpf_probe_read_kernel(p, 4, 0);			\
	}								\
	SEC("?" type)							\
	__description(type ": reject helper read ctx with variable offset") \
	__failure __msg("variable ctx access var_off=")			\
	int no_rewrite_##name##_helper_read_var(void *ctx)		\
	{								\
		__u64 off_var = bpf_get_prandom_u32();			\
		char *p = ctx;						\
									\
		off_var &= 4;						\
		p += off_var;						\
		return bpf_strncmp(p, 4, ctx_strncmp_target);		\
	}								\
	SEC("?" type)							\
	__description(type ": reject helper write ctx with variable offset") \
	__failure __msg("variable ctx access var_off=")			\
	int no_rewrite_##name##_helper_write_var(void *ctx)		\
	{								\
		__u64 off_var = bpf_get_prandom_u32();			\
		char *p = ctx;						\
									\
		off_var &= 4;						\
		p += off_var;						\
		return bpf_probe_read_kernel(p, 4, 0);			\
	}								\
	SEC("?" type)							\
	__description(type ": reject helper read zero-sized ctx access") \
	__failure __msg("R4 type=ctx expected=fp")			\
	int no_rewrite_##name##_helper_read_zero(void *ctx)		\
	{								\
		return bpf_snprintf(0, 0, ctx_snprintf_fmt, ctx, 0);	\
	}								\
	SEC("?" type)							\
	__description(type ": reject helper write zero-sized ctx access") \
	__failure __msg("R1 type=ctx expected=fp")			\
	int no_rewrite_##name##_helper_write_zero(void *ctx)		\
	{								\
		return bpf_probe_read_kernel(ctx, 0, 0);			\
	}								\
	SEC("?" type)							\
	__description(type ": reject kfunc ctx at fixed offset")	\
	__failure __msg("dereference of modified ctx ptr")		\
	int no_rewrite_##name##_kfunc_fixed(void *ctx)		\
	{								\
		char *p = ctx;						\
									\
		p += off;						\
		bpf_kfunc_call_test_mem_len_pass1(p, 4);		\
		return 0;						\
	}								\
	SEC("?" type)							\
	__description(type ": reject kfunc ctx with variable offset")	\
	__failure __msg("variable ctx access var_off=")			\
	int no_rewrite_##name##_kfunc_var(void *ctx)			\
	{								\
		__u64 off_var = bpf_get_prandom_u32();			\
		char *p = ctx;						\
									\
		off_var &= 4;						\
		p += off_var;						\
		bpf_kfunc_call_test_mem_len_pass1(p, 4);		\
		return 0;						\
	}								\
	SEC("?" type)							\
	__description(type ": reject kfunc zero-sized ctx access")	\
	__failure __msg("R1 type=ctx expected=fp")			\
	int no_rewrite_##name##_kfunc_zero(void *ctx)			\
	{								\
		bpf_kfunc_call_test_mem_len_pass1(ctx, 0);		\
		return 0;						\
	}

no_rewrite_ctx_access("kprobe", kprobe, 8, u64);
no_rewrite_ctx_access("tracepoint", tp, 8, u64);
no_rewrite_ctx_access("raw_tp", raw_tp, 8, u64);
no_rewrite_ctx_access("raw_tracepoint.w", raw_tp_w, 8, u64);
no_rewrite_ctx_access("fentry/bpf_modify_return_test", fentry, 8, u64);
no_rewrite_ctx_access("cgroup/dev", cgroup_dev, 4, u32);
no_rewrite_ctx_access("netfilter", netfilter, offsetof(struct bpf_nf_ctx, skb), u64);

char _license[] SEC("license") = "GPL";