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-rw-r--r--include/uapi/linux/bpf.h2
-rw-r--r--include/uapi/linux/filter.h7
-rw-r--r--net/core/filter.c41
-rw-r--r--net/sched/act_bpf.c3
-rw-r--r--net/sched/cls_bpf.c3
-rw-r--r--samples/bpf/tcbpf1_kern.c16
6 files changed, 50 insertions, 22 deletions
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 5c1cee11f777..a9ebdf5701e8 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -177,7 +177,7 @@ enum bpf_func_id {
/**
* skb_store_bytes(skb, offset, from, len, flags) - store bytes into packet
* @skb: pointer to skb
- * @offset: offset within packet from skb->data
+ * @offset: offset within packet from skb->mac_header
* @from: pointer where to copy bytes from
* @len: number of bytes to store into packet
* @flags: bit 0 - if true, recompute skb->csum
diff --git a/include/uapi/linux/filter.h b/include/uapi/linux/filter.h
index 34c7936ca114..c97340e43dd6 100644
--- a/include/uapi/linux/filter.h
+++ b/include/uapi/linux/filter.h
@@ -79,8 +79,11 @@ struct sock_fprog { /* Required for SO_ATTACH_FILTER. */
#define SKF_AD_RANDOM 56
#define SKF_AD_VLAN_TPID 60
#define SKF_AD_MAX 64
-#define SKF_NET_OFF (-0x100000)
-#define SKF_LL_OFF (-0x200000)
+#define SKF_NET_OFF (-0x100000)
+#define SKF_LL_OFF (-0x200000)
+
+#define BPF_NET_OFF SKF_NET_OFF
+#define BPF_LL_OFF SKF_LL_OFF
#endif /* _UAPI__LINUX_FILTER_H__ */
diff --git a/net/core/filter.c b/net/core/filter.c
index b669e75d2b36..bf831a85c315 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1175,12 +1175,27 @@ int sk_attach_bpf(u32 ufd, struct sock *sk)
return 0;
}
+/**
+ * bpf_skb_clone_not_writable - is the header of a clone not writable
+ * @skb: buffer to check
+ * @len: length up to which to write, can be negative
+ *
+ * Returns true if modifying the header part of the cloned buffer
+ * does require the data to be copied. I.e. this version works with
+ * negative lengths needed for eBPF case!
+ */
+static bool bpf_skb_clone_unwritable(const struct sk_buff *skb, int len)
+{
+ return skb_header_cloned(skb) ||
+ (int) skb_headroom(skb) + len > skb->hdr_len;
+}
+
#define BPF_RECOMPUTE_CSUM(flags) ((flags) & 1)
static u64 bpf_skb_store_bytes(u64 r1, u64 r2, u64 r3, u64 r4, u64 flags)
{
struct sk_buff *skb = (struct sk_buff *) (long) r1;
- unsigned int offset = (unsigned int) r2;
+ int offset = (int) r2;
void *from = (void *) (long) r3;
unsigned int len = (unsigned int) r4;
char buf[16];
@@ -1194,10 +1209,12 @@ static u64 bpf_skb_store_bytes(u64 r1, u64 r2, u64 r3, u64 r4, u64 flags)
*
* so check for invalid 'offset' and too large 'len'
*/
- if (unlikely(offset > 0xffff || len > sizeof(buf)))
+ if (unlikely((u32) offset > 0xffff || len > sizeof(buf)))
return -EFAULT;
- if (skb_cloned(skb) && !skb_clone_writable(skb, offset + len))
+ offset -= skb->data - skb_mac_header(skb);
+ if (unlikely(skb_cloned(skb) &&
+ bpf_skb_clone_unwritable(skb, offset + len)))
return -EFAULT;
ptr = skb_header_pointer(skb, offset, len, buf);
@@ -1232,15 +1249,18 @@ const struct bpf_func_proto bpf_skb_store_bytes_proto = {
#define BPF_HEADER_FIELD_SIZE(flags) ((flags) & 0x0f)
#define BPF_IS_PSEUDO_HEADER(flags) ((flags) & 0x10)
-static u64 bpf_l3_csum_replace(u64 r1, u64 offset, u64 from, u64 to, u64 flags)
+static u64 bpf_l3_csum_replace(u64 r1, u64 r2, u64 from, u64 to, u64 flags)
{
struct sk_buff *skb = (struct sk_buff *) (long) r1;
+ int offset = (int) r2;
__sum16 sum, *ptr;
- if (unlikely(offset > 0xffff))
+ if (unlikely((u32) offset > 0xffff))
return -EFAULT;
- if (skb_cloned(skb) && !skb_clone_writable(skb, offset + sizeof(sum)))
+ offset -= skb->data - skb_mac_header(skb);
+ if (unlikely(skb_cloned(skb) &&
+ bpf_skb_clone_unwritable(skb, offset + sizeof(sum))))
return -EFAULT;
ptr = skb_header_pointer(skb, offset, sizeof(sum), &sum);
@@ -1276,16 +1296,19 @@ const struct bpf_func_proto bpf_l3_csum_replace_proto = {
.arg5_type = ARG_ANYTHING,
};
-static u64 bpf_l4_csum_replace(u64 r1, u64 offset, u64 from, u64 to, u64 flags)
+static u64 bpf_l4_csum_replace(u64 r1, u64 r2, u64 from, u64 to, u64 flags)
{
struct sk_buff *skb = (struct sk_buff *) (long) r1;
u32 is_pseudo = BPF_IS_PSEUDO_HEADER(flags);
+ int offset = (int) r2;
__sum16 sum, *ptr;
- if (unlikely(offset > 0xffff))
+ if (unlikely((u32) offset > 0xffff))
return -EFAULT;
- if (skb_cloned(skb) && !skb_clone_writable(skb, offset + sizeof(sum)))
+ offset -= skb->data - skb_mac_header(skb);
+ if (unlikely(skb_cloned(skb) &&
+ bpf_skb_clone_unwritable(skb, offset + sizeof(sum))))
return -EFAULT;
ptr = skb_header_pointer(skb, offset, sizeof(sum), &sum);
diff --git a/net/sched/act_bpf.c b/net/sched/act_bpf.c
index 4d2cede17468..dc6a2d324bd8 100644
--- a/net/sched/act_bpf.c
+++ b/net/sched/act_bpf.c
@@ -38,6 +38,9 @@ static int tcf_bpf(struct sk_buff *skb, const struct tc_action *act,
struct tcf_bpf *prog = act->priv;
int action, filter_res;
+ if (unlikely(!skb_mac_header_was_set(skb)))
+ return TC_ACT_UNSPEC;
+
spin_lock(&prog->tcf_lock);
prog->tcf_tm.lastuse = jiffies;
diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c
index 5c4171c5d2bd..91bd9c19471d 100644
--- a/net/sched/cls_bpf.c
+++ b/net/sched/cls_bpf.c
@@ -66,6 +66,9 @@ static int cls_bpf_classify(struct sk_buff *skb, const struct tcf_proto *tp,
struct cls_bpf_prog *prog;
int ret = -1;
+ if (unlikely(!skb_mac_header_was_set(skb)))
+ return -1;
+
/* Needed here for accessing maps. */
rcu_read_lock();
list_for_each_entry_rcu(prog, &head->plist, link) {
diff --git a/samples/bpf/tcbpf1_kern.c b/samples/bpf/tcbpf1_kern.c
index 7cf3f42a6e39..7c27710f8296 100644
--- a/samples/bpf/tcbpf1_kern.c
+++ b/samples/bpf/tcbpf1_kern.c
@@ -4,6 +4,8 @@
#include <uapi/linux/ip.h>
#include <uapi/linux/in.h>
#include <uapi/linux/tcp.h>
+#include <uapi/linux/filter.h>
+
#include "bpf_helpers.h"
/* compiler workaround */
@@ -14,18 +16,12 @@ static inline void set_dst_mac(struct __sk_buff *skb, char *mac)
bpf_skb_store_bytes(skb, 0, mac, ETH_ALEN, 1);
}
-/* use 1 below for ingress qdisc and 0 for egress */
-#if 0
-#undef ETH_HLEN
-#define ETH_HLEN 0
-#endif
-
#define IP_CSUM_OFF (ETH_HLEN + offsetof(struct iphdr, check))
#define TOS_OFF (ETH_HLEN + offsetof(struct iphdr, tos))
static inline void set_ip_tos(struct __sk_buff *skb, __u8 new_tos)
{
- __u8 old_tos = load_byte(skb, TOS_OFF);
+ __u8 old_tos = load_byte(skb, BPF_LL_OFF + TOS_OFF);
bpf_l3_csum_replace(skb, IP_CSUM_OFF, htons(old_tos), htons(new_tos), 2);
bpf_skb_store_bytes(skb, TOS_OFF, &new_tos, sizeof(new_tos), 0);
@@ -38,7 +34,7 @@ static inline void set_ip_tos(struct __sk_buff *skb, __u8 new_tos)
static inline void set_tcp_ip_src(struct __sk_buff *skb, __u32 new_ip)
{
- __u32 old_ip = _htonl(load_word(skb, IP_SRC_OFF));
+ __u32 old_ip = _htonl(load_word(skb, BPF_LL_OFF + IP_SRC_OFF));
bpf_l4_csum_replace(skb, TCP_CSUM_OFF, old_ip, new_ip, IS_PSEUDO | sizeof(new_ip));
bpf_l3_csum_replace(skb, IP_CSUM_OFF, old_ip, new_ip, sizeof(new_ip));
@@ -48,7 +44,7 @@ static inline void set_tcp_ip_src(struct __sk_buff *skb, __u32 new_ip)
#define TCP_DPORT_OFF (ETH_HLEN + sizeof(struct iphdr) + offsetof(struct tcphdr, dest))
static inline void set_tcp_dest_port(struct __sk_buff *skb, __u16 new_port)
{
- __u16 old_port = htons(load_half(skb, TCP_DPORT_OFF));
+ __u16 old_port = htons(load_half(skb, BPF_LL_OFF + TCP_DPORT_OFF));
bpf_l4_csum_replace(skb, TCP_CSUM_OFF, old_port, new_port, sizeof(new_port));
bpf_skb_store_bytes(skb, TCP_DPORT_OFF, &new_port, sizeof(new_port), 0);
@@ -57,7 +53,7 @@ static inline void set_tcp_dest_port(struct __sk_buff *skb, __u16 new_port)
SEC("classifier")
int bpf_prog1(struct __sk_buff *skb)
{
- __u8 proto = load_byte(skb, ETH_HLEN + offsetof(struct iphdr, protocol));
+ __u8 proto = load_byte(skb, BPF_LL_OFF + ETH_HLEN + offsetof(struct iphdr, protocol));
long *value;
if (proto == IPPROTO_TCP) {
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.