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linux-stable/net/bpf/test_run.c
KP Singh 3d08b6f29c bpf: Add selftests for BPF_MODIFY_RETURN 
Test for two scenarios:

  * When the fmod_ret program returns 0, the original function should
    be called along with fentry and fexit programs.
  * When the fmod_ret program returns a non-zero value, the original
    function should not be called, no side effect should be observed and
    fentry and fexit programs should be called.

The result from the kernel function call and whether a side-effect is
observed is returned via the retval attr of the BPF_PROG_TEST_RUN (bpf)
syscall.

Signed-off-by: KP Singh <kpsingh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200304191853.1529-8-kpsingh@chromium.org
2020-03-04 13:41:06 -08:00

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// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2017 Facebook
*/
#include <linux/bpf.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/etherdevice.h>
#include <linux/filter.h>
#include <linux/sched/signal.h>
#include <net/bpf_sk_storage.h>
#include <net/sock.h>
#include <net/tcp.h>
#include <linux/error-injection.h>
#define CREATE_TRACE_POINTS
#include <trace/events/bpf_test_run.h>
static int bpf_test_run(struct bpf_prog *prog, void *ctx, u32 repeat,
u32 *retval, u32 *time, bool xdp)
{
struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE] = { NULL };
enum bpf_cgroup_storage_type stype;
u64 time_start, time_spent = 0;
int ret = 0;
u32 i;
for_each_cgroup_storage_type(stype) {
storage[stype] = bpf_cgroup_storage_alloc(prog, stype);
if (IS_ERR(storage[stype])) {
storage[stype] = NULL;
for_each_cgroup_storage_type(stype)
bpf_cgroup_storage_free(storage[stype]);
return -ENOMEM;
}
}
if (!repeat)
repeat = 1;
rcu_read_lock();
migrate_disable();
time_start = ktime_get_ns();
for (i = 0; i < repeat; i++) {
bpf_cgroup_storage_set(storage);
if (xdp)
*retval = bpf_prog_run_xdp(prog, ctx);
else
*retval = BPF_PROG_RUN(prog, ctx);
if (signal_pending(current)) {
ret = -EINTR;
break;
}
if (need_resched()) {
time_spent += ktime_get_ns() - time_start;
migrate_enable();
rcu_read_unlock();
cond_resched();
rcu_read_lock();
migrate_disable();
time_start = ktime_get_ns();
}
}
time_spent += ktime_get_ns() - time_start;
migrate_enable();
rcu_read_unlock();
do_div(time_spent, repeat);
*time = time_spent > U32_MAX ? U32_MAX : (u32)time_spent;
for_each_cgroup_storage_type(stype)
bpf_cgroup_storage_free(storage[stype]);
return ret;
}
static int bpf_test_finish(const union bpf_attr *kattr,
union bpf_attr __user *uattr, const void *data,
u32 size, u32 retval, u32 duration)
{
void __user *data_out = u64_to_user_ptr(kattr->test.data_out);
int err = -EFAULT;
u32 copy_size = size;
/* Clamp copy if the user has provided a size hint, but copy the full
* buffer if not to retain old behaviour.
*/
if (kattr->test.data_size_out &&
copy_size > kattr->test.data_size_out) {
copy_size = kattr->test.data_size_out;
err = -ENOSPC;
}
if (data_out && copy_to_user(data_out, data, copy_size))
goto out;
if (copy_to_user(&uattr->test.data_size_out, &size, sizeof(size)))
goto out;
if (copy_to_user(&uattr->test.retval, &retval, sizeof(retval)))
goto out;
if (copy_to_user(&uattr->test.duration, &duration, sizeof(duration)))
goto out;
if (err != -ENOSPC)
err = 0;
out:
trace_bpf_test_finish(&err);
return err;
}
/* Integer types of various sizes and pointer combinations cover variety of
* architecture dependent calling conventions. 7+ can be supported in the
* future.
*/
int noinline bpf_fentry_test1(int a)
{
return a + 1;
}
int noinline bpf_fentry_test2(int a, u64 b)
{
return a + b;
}
int noinline bpf_fentry_test3(char a, int b, u64 c)
{
return a + b + c;
}
int noinline bpf_fentry_test4(void *a, char b, int c, u64 d)
{
return (long)a + b + c + d;
}
int noinline bpf_fentry_test5(u64 a, void *b, short c, int d, u64 e)
{
return a + (long)b + c + d + e;
}
int noinline bpf_fentry_test6(u64 a, void *b, short c, int d, void *e, u64 f)
{
return a + (long)b + c + d + (long)e + f;
}
int noinline bpf_modify_return_test(int a, int *b)
{
*b += 1;
return a + *b;
}
ALLOW_ERROR_INJECTION(bpf_modify_return_test, ERRNO);
static void *bpf_test_init(const union bpf_attr *kattr, u32 size,
u32 headroom, u32 tailroom)
{
void __user *data_in = u64_to_user_ptr(kattr->test.data_in);
void *data;
if (size < ETH_HLEN || size > PAGE_SIZE - headroom - tailroom)
return ERR_PTR(-EINVAL);
data = kzalloc(size + headroom + tailroom, GFP_USER);
if (!data)
return ERR_PTR(-ENOMEM);
if (copy_from_user(data + headroom, data_in, size)) {
kfree(data);
return ERR_PTR(-EFAULT);
}
return data;
}
int bpf_prog_test_run_tracing(struct bpf_prog *prog,
const union bpf_attr *kattr,
union bpf_attr __user *uattr)
{
u16 side_effect = 0, ret = 0;
int b = 2, err = -EFAULT;
u32 retval = 0;
switch (prog->expected_attach_type) {
case BPF_TRACE_FENTRY:
case BPF_TRACE_FEXIT:
if (bpf_fentry_test1(1) != 2 ||
bpf_fentry_test2(2, 3) != 5 ||
bpf_fentry_test3(4, 5, 6) != 15 ||
bpf_fentry_test4((void *)7, 8, 9, 10) != 34 ||
bpf_fentry_test5(11, (void *)12, 13, 14, 15) != 65 ||
bpf_fentry_test6(16, (void *)17, 18, 19, (void *)20, 21) != 111)
goto out;
break;
case BPF_MODIFY_RETURN:
ret = bpf_modify_return_test(1, &b);
if (b != 2)
side_effect = 1;
break;
default:
goto out;
}
retval = ((u32)side_effect << 16) | ret;
if (copy_to_user(&uattr->test.retval, &retval, sizeof(retval)))
goto out;
err = 0;
out:
trace_bpf_test_finish(&err);
return err;
}
static void *bpf_ctx_init(const union bpf_attr *kattr, u32 max_size)
{
void __user *data_in = u64_to_user_ptr(kattr->test.ctx_in);
void __user *data_out = u64_to_user_ptr(kattr->test.ctx_out);
u32 size = kattr->test.ctx_size_in;
void *data;
int err;
if (!data_in && !data_out)
return NULL;
data = kzalloc(max_size, GFP_USER);
if (!data)
return ERR_PTR(-ENOMEM);
if (data_in) {
err = bpf_check_uarg_tail_zero(data_in, max_size, size);
if (err) {
kfree(data);
return ERR_PTR(err);
}
size = min_t(u32, max_size, size);
if (copy_from_user(data, data_in, size)) {
kfree(data);
return ERR_PTR(-EFAULT);
}
}
return data;
}
static int bpf_ctx_finish(const union bpf_attr *kattr,
union bpf_attr __user *uattr, const void *data,
u32 size)
{
void __user *data_out = u64_to_user_ptr(kattr->test.ctx_out);
int err = -EFAULT;
u32 copy_size = size;
if (!data || !data_out)
return 0;
if (copy_size > kattr->test.ctx_size_out) {
copy_size = kattr->test.ctx_size_out;
err = -ENOSPC;
}
if (copy_to_user(data_out, data, copy_size))
goto out;
if (copy_to_user(&uattr->test.ctx_size_out, &size, sizeof(size)))
goto out;
if (err != -ENOSPC)
err = 0;
out:
return err;
}
/**
* range_is_zero - test whether buffer is initialized
* @buf: buffer to check
* @from: check from this position
* @to: check up until (excluding) this position
*
* This function returns true if the there is a non-zero byte
* in the buf in the range [from,to).
*/
static inline bool range_is_zero(void *buf, size_t from, size_t to)
{
return !memchr_inv((u8 *)buf + from, 0, to - from);
}
static int convert___skb_to_skb(struct sk_buff *skb, struct __sk_buff *__skb)
{
struct qdisc_skb_cb *cb = (struct qdisc_skb_cb *)skb->cb;
if (!__skb)
return 0;
/* make sure the fields we don't use are zeroed */
if (!range_is_zero(__skb, 0, offsetof(struct __sk_buff, mark)))
return -EINVAL;
/* mark is allowed */
if (!range_is_zero(__skb, offsetofend(struct __sk_buff, mark),
offsetof(struct __sk_buff, priority)))
return -EINVAL;
/* priority is allowed */
if (!range_is_zero(__skb, offsetofend(struct __sk_buff, priority),
offsetof(struct __sk_buff, cb)))
return -EINVAL;
/* cb is allowed */
if (!range_is_zero(__skb, offsetofend(struct __sk_buff, cb),
offsetof(struct __sk_buff, tstamp)))
return -EINVAL;
/* tstamp is allowed */
/* wire_len is allowed */
/* gso_segs is allowed */
if (!range_is_zero(__skb, offsetofend(struct __sk_buff, gso_segs),
offsetof(struct __sk_buff, gso_size)))
return -EINVAL;
/* gso_size is allowed */
if (!range_is_zero(__skb, offsetofend(struct __sk_buff, gso_size),
sizeof(struct __sk_buff)))
return -EINVAL;
skb->mark = __skb->mark;
skb->priority = __skb->priority;
skb->tstamp = __skb->tstamp;
memcpy(&cb->data, __skb->cb, QDISC_CB_PRIV_LEN);
if (__skb->wire_len == 0) {
cb->pkt_len = skb->len;
} else {
if (__skb->wire_len < skb->len ||
__skb->wire_len > GSO_MAX_SIZE)
return -EINVAL;
cb->pkt_len = __skb->wire_len;
}
if (__skb->gso_segs > GSO_MAX_SEGS)
return -EINVAL;
skb_shinfo(skb)->gso_segs = __skb->gso_segs;
skb_shinfo(skb)->gso_size = __skb->gso_size;
return 0;
}
static void convert_skb_to___skb(struct sk_buff *skb, struct __sk_buff *__skb)
{
struct qdisc_skb_cb *cb = (struct qdisc_skb_cb *)skb->cb;
if (!__skb)
return;
__skb->mark = skb->mark;
__skb->priority = skb->priority;
__skb->tstamp = skb->tstamp;
memcpy(__skb->cb, &cb->data, QDISC_CB_PRIV_LEN);
__skb->wire_len = cb->pkt_len;
__skb->gso_segs = skb_shinfo(skb)->gso_segs;
}
int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
union bpf_attr __user *uattr)
{
bool is_l2 = false, is_direct_pkt_access = false;
u32 size = kattr->test.data_size_in;
u32 repeat = kattr->test.repeat;
struct __sk_buff *ctx = NULL;
u32 retval, duration;
int hh_len = ETH_HLEN;
struct sk_buff *skb;
struct sock *sk;
void *data;
int ret;
data = bpf_test_init(kattr, size, NET_SKB_PAD + NET_IP_ALIGN,
SKB_DATA_ALIGN(sizeof(struct skb_shared_info)));
if (IS_ERR(data))
return PTR_ERR(data);
ctx = bpf_ctx_init(kattr, sizeof(struct __sk_buff));
if (IS_ERR(ctx)) {
kfree(data);
return PTR_ERR(ctx);
}
switch (prog->type) {
case BPF_PROG_TYPE_SCHED_CLS:
case BPF_PROG_TYPE_SCHED_ACT:
is_l2 = true;
/* fall through */
case BPF_PROG_TYPE_LWT_IN:
case BPF_PROG_TYPE_LWT_OUT:
case BPF_PROG_TYPE_LWT_XMIT:
is_direct_pkt_access = true;
break;
default:
break;
}
sk = kzalloc(sizeof(struct sock), GFP_USER);
if (!sk) {
kfree(data);
kfree(ctx);
return -ENOMEM;
}
sock_net_set(sk, current->nsproxy->net_ns);
sock_init_data(NULL, sk);
skb = build_skb(data, 0);
if (!skb) {
kfree(data);
kfree(ctx);
kfree(sk);
return -ENOMEM;
}
skb->sk = sk;
skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
__skb_put(skb, size);
skb->protocol = eth_type_trans(skb, current->nsproxy->net_ns->loopback_dev);
skb_reset_network_header(skb);
if (is_l2)
__skb_push(skb, hh_len);
if (is_direct_pkt_access)
bpf_compute_data_pointers(skb);
ret = convert___skb_to_skb(skb, ctx);
if (ret)
goto out;
ret = bpf_test_run(prog, skb, repeat, &retval, &duration, false);
if (ret)
goto out;
if (!is_l2) {
if (skb_headroom(skb) < hh_len) {
int nhead = HH_DATA_ALIGN(hh_len - skb_headroom(skb));
if (pskb_expand_head(skb, nhead, 0, GFP_USER)) {
ret = -ENOMEM;
goto out;
}
}
memset(__skb_push(skb, hh_len), 0, hh_len);
}
convert_skb_to___skb(skb, ctx);
size = skb->len;
/* bpf program can never convert linear skb to non-linear */
if (WARN_ON_ONCE(skb_is_nonlinear(skb)))
size = skb_headlen(skb);
ret = bpf_test_finish(kattr, uattr, skb->data, size, retval, duration);
if (!ret)
ret = bpf_ctx_finish(kattr, uattr, ctx,
sizeof(struct __sk_buff));
out:
kfree_skb(skb);
bpf_sk_storage_free(sk);
kfree(sk);
kfree(ctx);
return ret;
}
int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
union bpf_attr __user *uattr)
{
u32 size = kattr->test.data_size_in;
u32 repeat = kattr->test.repeat;
struct netdev_rx_queue *rxqueue;
struct xdp_buff xdp = {};
u32 retval, duration;
void *data;
int ret;
if (kattr->test.ctx_in || kattr->test.ctx_out)
return -EINVAL;
data = bpf_test_init(kattr, size, XDP_PACKET_HEADROOM + NET_IP_ALIGN, 0);
if (IS_ERR(data))
return PTR_ERR(data);
xdp.data_hard_start = data;
xdp.data = data + XDP_PACKET_HEADROOM + NET_IP_ALIGN;
xdp.data_meta = xdp.data;
xdp.data_end = xdp.data + size;
rxqueue = __netif_get_rx_queue(current->nsproxy->net_ns->loopback_dev, 0);
xdp.rxq = &rxqueue->xdp_rxq;
bpf_prog_change_xdp(NULL, prog);
ret = bpf_test_run(prog, &xdp, repeat, &retval, &duration, true);
if (ret)
goto out;
if (xdp.data != data + XDP_PACKET_HEADROOM + NET_IP_ALIGN ||
xdp.data_end != xdp.data + size)
size = xdp.data_end - xdp.data;
ret = bpf_test_finish(kattr, uattr, xdp.data, size, retval, duration);
out:
bpf_prog_change_xdp(prog, NULL);
kfree(data);
return ret;
}
static int verify_user_bpf_flow_keys(struct bpf_flow_keys *ctx)
{
/* make sure the fields we don't use are zeroed */
if (!range_is_zero(ctx, 0, offsetof(struct bpf_flow_keys, flags)))
return -EINVAL;
/* flags is allowed */
if (!range_is_zero(ctx, offsetofend(struct bpf_flow_keys, flags),
sizeof(struct bpf_flow_keys)))
return -EINVAL;
return 0;
}
int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
const union bpf_attr *kattr,
union bpf_attr __user *uattr)
{
u32 size = kattr->test.data_size_in;
struct bpf_flow_dissector ctx = {};
u32 repeat = kattr->test.repeat;
struct bpf_flow_keys *user_ctx;
struct bpf_flow_keys flow_keys;
u64 time_start, time_spent = 0;
const struct ethhdr *eth;
unsigned int flags = 0;
u32 retval, duration;
void *data;
int ret;
u32 i;
if (prog->type != BPF_PROG_TYPE_FLOW_DISSECTOR)
return -EINVAL;
if (size < ETH_HLEN)
return -EINVAL;
data = bpf_test_init(kattr, size, 0, 0);
if (IS_ERR(data))
return PTR_ERR(data);
eth = (struct ethhdr *)data;
if (!repeat)
repeat = 1;
user_ctx = bpf_ctx_init(kattr, sizeof(struct bpf_flow_keys));
if (IS_ERR(user_ctx)) {
kfree(data);
return PTR_ERR(user_ctx);
}
if (user_ctx) {
ret = verify_user_bpf_flow_keys(user_ctx);
if (ret)
goto out;
flags = user_ctx->flags;
}
ctx.flow_keys = &flow_keys;
ctx.data = data;
ctx.data_end = (__u8 *)data + size;
rcu_read_lock();
preempt_disable();
time_start = ktime_get_ns();
for (i = 0; i < repeat; i++) {
retval = bpf_flow_dissect(prog, &ctx, eth->h_proto, ETH_HLEN,
size, flags);
if (signal_pending(current)) {
preempt_enable();
rcu_read_unlock();
ret = -EINTR;
goto out;
}
if (need_resched()) {
time_spent += ktime_get_ns() - time_start;
preempt_enable();
rcu_read_unlock();
cond_resched();
rcu_read_lock();
preempt_disable();
time_start = ktime_get_ns();
}
}
time_spent += ktime_get_ns() - time_start;
preempt_enable();
rcu_read_unlock();
do_div(time_spent, repeat);
duration = time_spent > U32_MAX ? U32_MAX : (u32)time_spent;
ret = bpf_test_finish(kattr, uattr, &flow_keys, sizeof(flow_keys),
retval, duration);
if (!ret)
ret = bpf_ctx_finish(kattr, uattr, user_ctx,
sizeof(struct bpf_flow_keys));
out:
kfree(user_ctx);
kfree(data);
return ret;
}
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