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

Source file repositories/reference/linux-study-clean/tools/testing/selftests/bpf/progs/verifier_ctx.c

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/bpf/progs/verifier_ctx.c
Extension
.c
Size
20874 bytes
Lines
863
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

// 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)")

Annotation

Implementation Notes