toa: resolve ipv4_specific/tcp_v4_syn_recv_sock via kallsyms - #1067
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toa: resolve ipv4_specific/tcp_v4_syn_recv_sock via kallsyms#1067pubyun wants to merge 2 commits into
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Debian kernel 6.12.94 stopped exporting ipv4_specific and tcp_v4_syn_recv_sock, so the IPv4 hook path failed to link (modpost: "xxx" undefined; 6.12.90 still built). Resolve both at runtime with kallsyms_lookup_name() in toa_init(), mirroring the existing IPv6 path, and route hook/unhook and the original syn_recv_sock chain-call through the saved pointers. Also unregister the kprobe on the toa_init() error path: a failed module_init() never triggers module_exit(), so the kprobe registered to bootstrap kallsyms_lookup_name() would otherwise leak (also covers the pre-existing goto-err paths). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
) Upstream commit 858d2a4f67ff ("tcp: fix potential race in tcp_v6_syn_recv_sock()", merged in v7.0) added a 7th argument void (*opt_child_init)(struct sock *, const struct sock *) to inet_connection_sock_af_ops.syn_recv_sock. It is backported per stable/distro: AlmaLinux/RHEL 10 carries it since kernel-6.12.0-211.28.1.el10_2 (10.0/10.1 and earlier 10.2 z-streams are still 6-arg); Debian/Ubuntu 6.12.y LTS will follow. Detect the argument by probing the kernel header for opt_child_init at build time (kmod/toa/Makefile) instead of any version macro: RHEL_RELEASE_CODE only has minor granularity and cannot express the z-stream boundary (211.7.4 and 211.30.1 are both 2562, yet 6- vs 7-arg). toa.c gates the 7-arg typedef, v4/v6 wrapper signatures and forwarding calls on TOA_SYN_RECV_SOCK_HAS_OPT_CHILD_INIT, forwarding opt_child_init untouched (the original syn_recv_sock owns invoking it). Verified on AlmaLinux 10.2 (6.12.0-211.30.1.el10_2): build + DKMS load + v4/v6 syn_recv_sock hook OK; Debian 6.12.x still takes the 6-arg path; older kernels 4-arg path unchanged.
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Debian kernel 6.12.94 stopped exporting
ipv4_specificandtcp_v4_syn_recv_sock, so the IPv4 hook path failed to link (modpost: "xxx" undefined; 6.12.90 still built). Resolve both at runtime withkallsyms_lookup_name()intoa_init(), mirroring the existing IPv6 path, and route hook/unhook and the originalsyn_recv_sockchain-call through the saved pointers.Also unregister the kprobe on the
toa_init()error path: a failedmodule_init()never triggersmodule_exit(), so the kprobe registered to bootstrapkallsyms_lookup_name()would otherwise leak (also covers the pre-existing goto-err paths).🤖 Generated with Claude Code