From f5b8b37eafeafe61895f574dec241ed140848249 Mon Sep 17 00:00:00 2001 From: Beniamino Galvani Date: Thu, 22 Feb 2018 18:09:33 +0100 Subject: [PATCH] libsystemd-network: fix endianness in ARP BPF filter systemd commit f11cba7479fe ("libsystemd-network: fix unaligned loads (issue #7654)") changed the way in which the MAC address is read to use native endiannes: htobe32(*((uint32_t *)x) -> unaligned_read_ne32(x) This is wrong because loads done with BPF_LD + BPF_ABS are big-endian, as it can be seen for the ethertype and arp-operation loads above in the filter. Also, the same commit changed: htobe32(*((unsigned int *)x) -> unaligned_read_be32(x) in _bind_raw_socket(), which is the correct form. The commit broke IPv4LL in presence of loops, as the sender now considers its own packets as conflicting. systemd commit: 6afe9046d570fd86dbc04526b5685c64d7958086 --- src/systemd/src/libsystemd-network/arp-util.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/systemd/src/libsystemd-network/arp-util.c b/src/systemd/src/libsystemd-network/arp-util.c index 11dcda8693..898801b367 100644 --- a/src/systemd/src/libsystemd-network/arp-util.c +++ b/src/systemd/src/libsystemd-network/arp-util.c @@ -51,12 +51,12 @@ int arp_network_bind_raw_socket(int ifindex, be32_t address, const struct ether_ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REPLY, 1, 0), /* protocol == reply ? */ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */ /* Sender Hardware Address must be different from our own */ - BPF_STMT(BPF_LD + BPF_IMM, unaligned_read_ne32(ð_mac->ether_addr_octet[0])),/* A <- 4 bytes of client's MAC */ + BPF_STMT(BPF_LD + BPF_IMM, unaligned_read_be32(ð_mac->ether_addr_octet[0])),/* A <- 4 bytes of client's MAC */ BPF_STMT(BPF_MISC + BPF_TAX, 0), /* X <- A */ BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(struct ether_arp, arp_sha)), /* A <- 4 bytes of SHA */ BPF_STMT(BPF_ALU + BPF_XOR + BPF_X, 0), /* A xor X */ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 0, 6), /* A == 0 ? */ - BPF_STMT(BPF_LD + BPF_IMM, unaligned_read_ne16(ð_mac->ether_addr_octet[4])),/* A <- remainder of client's MAC */ + BPF_STMT(BPF_LD + BPF_IMM, unaligned_read_be16(ð_mac->ether_addr_octet[4])),/* A <- remainder of client's MAC */ BPF_STMT(BPF_MISC + BPF_TAX, 0), /* X <- A */ BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, arp_sha) + 4), /* A <- remainder of SHA */ BPF_STMT(BPF_ALU + BPF_XOR + BPF_X, 0), /* A xor X */