| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <279ae3717cb3d03c0ffeb511493c93c450a01e1a.1591108731.git.daniel@iogearbox.net>
Date: Tue, 2 Jun 2020 16:58:33 +0200
From: Daniel Borkmann <daniel@...earbox.net>
To: alexei.starovoitov@...il.com
Cc: lmb@...udflare.com, alan.maguire@...cle.com, bpf@...r.kernel.org,
netdev@...r.kernel.org, Daniel Borkmann <daniel@...earbox.net>
Subject: [PATCH bpf 2/3] bpf: Add csum_level helper for fixing up csum levels
Add a bpf_csum_level() helper which BPF programs can use in combination
with bpf_skb_adjust_room() when they pass in BPF_F_ADJ_ROOM_NO_CSUM_RESET
flag to the latter to avoid falling back to CHECKSUM_NONE.
The bpf_csum_level() allows to adjust CHECKSUM_UNNECESSARY skb->csum_levels
via BPF_CSUM_LEVEL_{INC,DEC} which calls __skb_{incr,decr}_checksum_unnecessary()
on the skb. The helper also allows a BPF_CSUM_LEVEL_RESET which sets the skb's
csum to CHECKSUM_NONE as well as a BPF_CSUM_LEVEL_QUERY to just return the
current level. Without this helper, there is no way to otherwise adjust the
skb->csum_level. I did not add an extra dummy flags as there is plenty of free
bitspace in level argument itself iff ever needed in future.
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
---
include/uapi/linux/bpf.h | 43 +++++++++++++++++++++++++++++++++-
net/core/filter.c | 38 ++++++++++++++++++++++++++++++
tools/include/uapi/linux/bpf.h | 43 +++++++++++++++++++++++++++++++++-
3 files changed, 122 insertions(+), 2 deletions(-)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 3ba2bbbed80c..46622901cba7 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -3220,6 +3220,38 @@ union bpf_attr {
* calculation.
* Return
* Requested value, or 0, if flags are not recognized.
+ *
+ * int bpf_csum_level(struct sk_buff *skb, u64 level)
+ * Description
+ * Change the skbs checksum level by one layer up or down, or
+ * reset it entirely to none in order to have the stack perform
+ * checksum validation. The level is applicable to the following
+ * protocols: TCP, UDP, GRE, SCTP, FCOE. For example, a decap of
+ * | ETH | IP | UDP | GUE | IP | TCP | into | ETH | IP | TCP |
+ * through **bpf_skb_adjust_room**\ () helper with passing in
+ * **BPF_F_ADJ_ROOM_NO_CSUM_RESET** flag would require one call
+ * to **bpf_csum_level**\ () with **BPF_CSUM_LEVEL_DEC** since
+ * the UDP header is removed. Similarly, an encap of the latter
+ * into the former could be accompanied by a helper call to
+ * **bpf_csum_level**\ () with **BPF_CSUM_LEVEL_INC** if the
+ * skb is still intended to be processed in higher layers of the
+ * stack instead of just egressing at tc.
+ *
+ * There are three supported level settings at this time:
+ *
+ * * **BPF_CSUM_LEVEL_INC**: Increases skb->csum_level for skbs
+ * with CHECKSUM_UNNECESSARY.
+ * * **BPF_CSUM_LEVEL_DEC**: Decreases skb->csum_level for skbs
+ * with CHECKSUM_UNNECESSARY.
+ * * **BPF_CSUM_LEVEL_RESET**: Resets skb->csum_level to 0 and
+ * sets CHECKSUM_NONE to force checksum validation by the stack.
+ * * **BPF_CSUM_LEVEL_QUERY**: No-op, returns the current
+ * skb->csum_level.
+ * Return
+ * 0 on success, or a negative error in case of failure. In the
+ * case of **BPF_CSUM_LEVEL_QUERY**, the current skb->csum_level
+ * is returned or the error code -EACCES in case the skb is not
+ * subject to CHECKSUM_UNNECESSARY.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -3356,7 +3388,8 @@ union bpf_attr {
FN(ringbuf_reserve), \
FN(ringbuf_submit), \
FN(ringbuf_discard), \
- FN(ringbuf_query),
+ FN(ringbuf_query), \
+ FN(csum_level),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
@@ -3433,6 +3466,14 @@ enum {
BPF_F_CURRENT_NETNS = (-1L),
};
+/* BPF_FUNC_csum_level level values. */
+enum {
+ BPF_CSUM_LEVEL_QUERY,
+ BPF_CSUM_LEVEL_INC,
+ BPF_CSUM_LEVEL_DEC,
+ BPF_CSUM_LEVEL_RESET,
+};
+
/* BPF_FUNC_skb_adjust_room flags. */
enum {
BPF_F_ADJ_ROOM_FIXED_GSO = (1ULL << 0),
diff --git a/net/core/filter.c b/net/core/filter.c
index 278dcc0af961..d01a244b5087 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2015,6 +2015,40 @@ static const struct bpf_func_proto bpf_csum_update_proto = {
.arg2_type = ARG_ANYTHING,
};
+BPF_CALL_2(bpf_csum_level, struct sk_buff *, skb, u64, level)
+{
+ /* The interface is to be used in combination with bpf_skb_adjust_room()
+ * for encap/decap of packet headers when BPF_F_ADJ_ROOM_NO_CSUM_RESET
+ * is passed as flags, for example.
+ */
+ switch (level) {
+ case BPF_CSUM_LEVEL_INC:
+ __skb_incr_checksum_unnecessary(skb);
+ break;
+ case BPF_CSUM_LEVEL_DEC:
+ __skb_decr_checksum_unnecessary(skb);
+ break;
+ case BPF_CSUM_LEVEL_RESET:
+ __skb_reset_checksum_unnecessary(skb);
+ break;
+ case BPF_CSUM_LEVEL_QUERY:
+ return skb->ip_summed == CHECKSUM_UNNECESSARY ?
+ skb->csum_level : -EACCES;
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static const struct bpf_func_proto bpf_csum_level_proto = {
+ .func = bpf_csum_level,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+ .arg2_type = ARG_ANYTHING,
+};
+
static inline int __bpf_rx_skb(struct net_device *dev, struct sk_buff *skb)
{
return dev_forward_skb(dev, skb);
@@ -6280,6 +6314,8 @@ tc_cls_act_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_csum_diff_proto;
case BPF_FUNC_csum_update:
return &bpf_csum_update_proto;
+ case BPF_FUNC_csum_level:
+ return &bpf_csum_level_proto;
case BPF_FUNC_l3_csum_replace:
return &bpf_l3_csum_replace_proto;
case BPF_FUNC_l4_csum_replace:
@@ -6613,6 +6649,8 @@ lwt_xmit_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_skb_store_bytes_proto;
case BPF_FUNC_csum_update:
return &bpf_csum_update_proto;
+ case BPF_FUNC_csum_level:
+ return &bpf_csum_level_proto;
case BPF_FUNC_l3_csum_replace:
return &bpf_l3_csum_replace_proto;
case BPF_FUNC_l4_csum_replace:
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 3ba2bbbed80c..46622901cba7 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -3220,6 +3220,38 @@ union bpf_attr {
* calculation.
* Return
* Requested value, or 0, if flags are not recognized.
+ *
+ * int bpf_csum_level(struct sk_buff *skb, u64 level)
+ * Description
+ * Change the skbs checksum level by one layer up or down, or
+ * reset it entirely to none in order to have the stack perform
+ * checksum validation. The level is applicable to the following
+ * protocols: TCP, UDP, GRE, SCTP, FCOE. For example, a decap of
+ * | ETH | IP | UDP | GUE | IP | TCP | into | ETH | IP | TCP |
+ * through **bpf_skb_adjust_room**\ () helper with passing in
+ * **BPF_F_ADJ_ROOM_NO_CSUM_RESET** flag would require one call
+ * to **bpf_csum_level**\ () with **BPF_CSUM_LEVEL_DEC** since
+ * the UDP header is removed. Similarly, an encap of the latter
+ * into the former could be accompanied by a helper call to
+ * **bpf_csum_level**\ () with **BPF_CSUM_LEVEL_INC** if the
+ * skb is still intended to be processed in higher layers of the
+ * stack instead of just egressing at tc.
+ *
+ * There are three supported level settings at this time:
+ *
+ * * **BPF_CSUM_LEVEL_INC**: Increases skb->csum_level for skbs
+ * with CHECKSUM_UNNECESSARY.
+ * * **BPF_CSUM_LEVEL_DEC**: Decreases skb->csum_level for skbs
+ * with CHECKSUM_UNNECESSARY.
+ * * **BPF_CSUM_LEVEL_RESET**: Resets skb->csum_level to 0 and
+ * sets CHECKSUM_NONE to force checksum validation by the stack.
+ * * **BPF_CSUM_LEVEL_QUERY**: No-op, returns the current
+ * skb->csum_level.
+ * Return
+ * 0 on success, or a negative error in case of failure. In the
+ * case of **BPF_CSUM_LEVEL_QUERY**, the current skb->csum_level
+ * is returned or the error code -EACCES in case the skb is not
+ * subject to CHECKSUM_UNNECESSARY.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -3356,7 +3388,8 @@ union bpf_attr {
FN(ringbuf_reserve), \
FN(ringbuf_submit), \
FN(ringbuf_discard), \
- FN(ringbuf_query),
+ FN(ringbuf_query), \
+ FN(csum_level),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
@@ -3433,6 +3466,14 @@ enum {
BPF_F_CURRENT_NETNS = (-1L),
};
+/* BPF_FUNC_csum_level level values. */
+enum {
+ BPF_CSUM_LEVEL_QUERY,
+ BPF_CSUM_LEVEL_INC,
+ BPF_CSUM_LEVEL_DEC,
+ BPF_CSUM_LEVEL_RESET,
+};
+
/* BPF_FUNC_skb_adjust_room flags. */
enum {
BPF_F_ADJ_ROOM_FIXED_GSO = (1ULL << 0),
--
2.21.0
Powered by blists - more mailing lists