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reject too-short PROXY v2 address length in mod_remoteip #683

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arshsmith1 wants to merge 2 commits into from
+20 −6
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reject too-short PROXY v2 address length in mod_remoteip #683

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aa6c438
reject too-short PROXY v2 address length in mod_remoteip
arshsmith1 Jul 13, 2026
bfcf178
mod_remoteip: use remoteip_get_v2_len for the v2 address length checks
arshsmith1 Jul 20, 2026
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26 changes: 20 additions & 6 deletions modules/metadata/mod_remoteip.c
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Original file line number Diff line number Diff line change
Expand Up @@ -931,6 +931,12 @@ static int remoteip_hook_pre_connection(conn_rec *c, void *csd)
return OK;
}

/** Return length for a v2 protocol header. */
static apr_size_t remoteip_get_v2_len(proxy_header *hdr)
{
return ntohs(hdr->v2.len);
}

/* Binary format:
* <sig><cmd><proto><addr-len><addr>
* sig = \x0D \x0A \x0D \x0A \x00 \x0D \x0A \x51 \x55 \x49 \x54 \x0A
Expand All @@ -954,6 +960,13 @@ static remoteip_parse_status_t remoteip_process_v2_header(conn_rec *c,
case 0x01: /* PROXY command */
switch (hdr->v2.fam) {
case 0x11: /* TCPv4 */
if (remoteip_get_v2_len(hdr) < sizeof(hdr->v2.addr.ip4)) {
ap_log_cerror(APLOG_MARK, APLOG_ERR, 0, c, APLOGNO()
"RemoteIPProxyProtocol: address length "
"%" APR_SIZE_T_FMT " too short for TCPv4",
remoteip_get_v2_len(hdr));
return HDR_ERROR;
}
ret = apr_sockaddr_info_get(&conn_conf->client_addr, NULL,
APR_INET,
ntohs(hdr->v2.addr.ip4.src_port),
Expand All @@ -971,6 +984,13 @@ static remoteip_parse_status_t remoteip_process_v2_header(conn_rec *c,

case 0x21: /* TCPv6 */
#if APR_HAVE_IPV6
if (remoteip_get_v2_len(hdr) < sizeof(hdr->v2.addr.ip6)) {
ap_log_cerror(APLOG_MARK, APLOG_ERR, 0, c, APLOGNO()
"RemoteIPProxyProtocol: address length "
"%" APR_SIZE_T_FMT " too short for TCPv6",
remoteip_get_v2_len(hdr));
return HDR_ERROR;
}
ret = apr_sockaddr_info_get(&conn_conf->client_addr, NULL,
APR_INET6,
ntohs(hdr->v2.addr.ip6.src_port),
Expand Down Expand Up @@ -1017,12 +1037,6 @@ static remoteip_parse_status_t remoteip_process_v2_header(conn_rec *c,
return HDR_DONE;
}

/** Return length for a v2 protocol header. */
static apr_size_t remoteip_get_v2_len(proxy_header *hdr)
{
return ntohs(hdr->v2.len);
}

/** Determine if this is a v1 or v2 PROXY header.
*/
static int remoteip_determine_version(conn_rec *c, const char *ptr)
Expand Down