911edc69c8
This little patch is a follow-up to: https://lore.kernel.org/bpf/20240507095011.15867-1-jose.marchesi@oracle.com/T/#u The temporary workaround of passing -DBPF_NO_PRESERVE_ACCESS_INDEX when building with GCC triggers a redefinition preprocessor error when building progs/skb_pkt_end.c. This patch adds a guard to avoid redefinition. Signed-off-by: Jose E. Marchesi <jose.marchesi@oracle.com> Cc: david.faust@oracle.com Cc: cupertino.miranda@oracle.com Cc: Eduard Zingerman <eddyz87@gmail.com> Cc: Yonghong Song <yonghong.song@linux.dev> Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com> Acked-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/r/20240508110332.17332-1-jose.marchesi@oracle.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
55 lines
1 KiB
C
55 lines
1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#ifndef BPF_NO_PRESERVE_ACCESS_INDEX
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#define BPF_NO_PRESERVE_ACCESS_INDEX
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#endif
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#include <vmlinux.h>
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#include <bpf/bpf_core_read.h>
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#include <bpf/bpf_helpers.h>
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#define INLINE __always_inline
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#define skb_shorter(skb, len) ((void *)(long)(skb)->data + (len) > (void *)(long)skb->data_end)
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#define ETH_IPV4_TCP_SIZE (14 + sizeof(struct iphdr) + sizeof(struct tcphdr))
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static INLINE struct iphdr *get_iphdr(struct __sk_buff *skb)
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{
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struct iphdr *ip = NULL;
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struct ethhdr *eth;
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if (skb_shorter(skb, ETH_IPV4_TCP_SIZE))
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goto out;
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eth = (void *)(long)skb->data;
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ip = (void *)(eth + 1);
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out:
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return ip;
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}
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SEC("tc")
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int main_prog(struct __sk_buff *skb)
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{
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struct iphdr *ip = NULL;
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struct tcphdr *tcp;
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__u8 proto = 0;
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if (!(ip = get_iphdr(skb)))
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goto out;
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proto = ip->protocol;
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if (proto != IPPROTO_TCP)
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goto out;
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tcp = (void*)(ip + 1);
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if (tcp->dest != 0)
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goto out;
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if (!tcp)
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goto out;
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return tcp->urg_ptr;
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out:
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return -1;
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}
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char _license[] SEC("license") = "GPL";
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