#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;
}
#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";
