From: Krzysztof Grzywocz <kgrzywocz@xxxxx> Problem: On 64bit kernel ELF32bit gets improper value of `SCTP_GET_ASSOC_STATS` (call `getsockopt` on SCTP socket) due to different `struct sctp_assoc_stats` aligment (mostly because of different `_K_SS_ALIGNSIZE`). Example: Sent 1000 bytes, Received 1000 bytes May result in: packets sent(sas_opackets): 12884901888 packets recv(sas_ipackets): 12884901888 Patch solution: Realign struct at the end of `sctp_getsockopt_assoc_stats(..)` when called in compat mode. See patch for details. For more details see: https://github.com/kgrzywocz/align_compat32_sctp_assoc_stats ----- diff --git a/net/sctp/socket.c b/net/sctp/socket.c index ce620e87..73963062 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -6685,6 +6685,65 @@ static int sctp_getsockopt_paddr_thresholds(struct sock *sk, return 0; } +#ifdef CONFIG_COMPAT + +struct __kernel_sockaddr_storage_compat32 { + __kernel_sa_family_t ss_family; /* address family */ + /* Following field(s) are implementation specific */ + char __data[_K_SS_MAXSIZE - sizeof(unsigned short)]; + /* space to achieve desired size, */ + /* _SS_MAXSIZE value minus size of ss_family */ +} __attribute__ ((packed,aligned(4))); /* force desired alignment */ + + +struct sctp_assoc_stats_compat32 { + int32_t sas_assoc_id; /* Input */ + /* Transport of observed max RTO */ + struct __kernel_sockaddr_storage_compat32 sas_obs_rto_ipaddr; + uint64_t sas_maxrto; /* Maximum Observed RTO for period */ + uint64_t sas_isacks; /* SACKs received */ + uint64_t sas_osacks; /* SACKs sent */ + uint64_t sas_opackets; /* Packets sent */ + uint64_t sas_ipackets; /* Packets received */ + uint64_t sas_rtxchunks; /* Retransmitted Chunks */ + uint64_t sas_outofseqtsns;/* TSN received > next expected */ + uint64_t sas_idupchunks; /* Dups received (ordered+unordered) */ + uint64_t sas_gapcnt; /* Gap Acknowledgements Received */ + uint64_t sas_ouodchunks; /* Unordered data chunks sent */ + uint64_t sas_iuodchunks; /* Unordered data chunks received */ + uint64_t sas_oodchunks; /* Ordered data chunks sent */ + uint64_t sas_iodchunks; /* Ordered data chunks received */ + uint64_t sas_octrlchunks; /* Control chunks sent */ + uint64_t sas_ictrlchunks; /* Control chunks received */ +} __attribute__ ((packed,aligned(4))); + + +static void align_compat32_sctp_assoc_stats(void *sctp_assoc_stats) +{ + struct sctp_assoc_stats* p64 = sctp_assoc_stats; + struct sctp_assoc_stats_compat32* p32 = sctp_assoc_stats; + + p32->sas_assoc_id = p64->sas_assoc_id; + p32->sas_obs_rto_ipaddr.ss_family = p64->sas_obs_rto_ipaddr.ss_family; + memcpy(p32->sas_obs_rto_ipaddr.__data, p64->sas_obs_rto_ipaddr.__data, sizeof(p32->sas_obs_rto_ipaddr.__data)); + p32->sas_maxrto = p64->sas_maxrto; + p32->sas_isacks = p64->sas_isacks; + p32->sas_osacks = p64->sas_osacks; + p32->sas_opackets = p64->sas_opackets; + p32->sas_ipackets = p64->sas_ipackets; + p32->sas_rtxchunks = p64->sas_rtxchunks; + p32->sas_outofseqtsns = p64->sas_outofseqtsns; + p32->sas_idupchunks = p64->sas_idupchunks; + p32->sas_gapcnt = p64->sas_gapcnt; + p32->sas_ouodchunks = p64->sas_ouodchunks; + p32->sas_iuodchunks = p64->sas_iuodchunks; + p32->sas_oodchunks = p64->sas_oodchunks; + p32->sas_iodchunks = p64->sas_iodchunks; + p32->sas_octrlchunks = p64->sas_octrlchunks; + p32->sas_ictrlchunks = p64->sas_ictrlchunks; +} +#endif + /* * SCTP_GET_ASSOC_STATS * @@ -6743,6 +6802,13 @@ static int sctp_getsockopt_assoc_stats(struct sock *sk, int len, pr_debug("%s: len:%d, assoc_id:%d\n", __func__, len, sas.sas_assoc_id); + #ifdef CONFIG_COMPAT + if (in_compat_syscall()) { + pr_debug("%s:running in compat32. Aligningsctp_assoc_stats\n", __func__); + align_compat32_sctp_assoc_stats(&sas); + } + #endif + if (copy_to_user(optval, &sas, len)) return -EFAULT;
