ipv4/inet_sock.h: Avoid thousands of -Wflex-array-member-not-at-end warnings

Use DEFINE_RAW_FLEX() to avoid thousands of -Wflex-array-member-not-at-end
warnings.

Remove struct ip_options_data, and adjust the rest of the code so that
flexible-array member struct ip_options_rcu::opt.__data[] ends last
in struct icmp_bxm.

Compensate for this by using the DEFINE_RAW_FLEX() helper to define each
on-stack struct instance that contained struct ip_options_data as a member,
and to define struct ip_options_rcu with a fixed on-stack size for its
nested flexible-array member opt.__data[].

Also, add a couple of code comments to prevent people from adding members
to a struct after another member that contains a flexible array.

With these changes, fix 2600 warnings of the following type:

include/net/inet_sock.h:65:33: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://patch.msgid.link/aVteBadWA6AbTp7X@kspp
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index ac1c75975908a993c8ffbb9a499caf515ff23034..3370159556b8602d1ceef06c0c742479452602df 100644 (file)
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -26,6 +26,8 @@
 #include <net/tcp_states.h>
 #include <net/l3mdev.h>
 
+#define IP_OPTIONS_DATA_FIXED_SIZE 40
+
 /** struct ip_options - IP Options
  *
  * @faddr - Saved first hop address
@@ -58,12 +60,9 @@ struct ip_options {
 
 struct ip_options_rcu {
        struct rcu_head rcu;
-       struct ip_options opt;
-};
 
-struct ip_options_data {
-       struct ip_options_rcu   opt;
-       char                    data[40];
+       /* Must be last as it ends in a flexible-array member. */
+       struct ip_options opt;
 };
 
 struct inet_request_sock {

diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 4abbec2f47ef58242b686f411109494e40c8d752..19c9c838967f761a8b3a1b07cea5c5ec932bf12d 100644 (file)
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -112,7 +112,9 @@ struct icmp_bxm {
                __be32         times[3];
        } data;
        int head_len;
-       struct ip_options_data replyopts;
+
+       /* Must be last as it ends in a flexible-array member. */
+       struct ip_options_rcu replyopts;
 };
 
 /* An array of errno for error messages from dest unreach. */
@@ -353,9 +355,12 @@ void icmp_out_count(struct net *net, unsigned char type)
 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
                          struct sk_buff *skb)
 {
-       struct icmp_bxm *icmp_param = from;
+       DEFINE_RAW_FLEX(struct icmp_bxm, icmp_param, replyopts.opt.__data,
+                       IP_OPTIONS_DATA_FIXED_SIZE);
        __wsum csum;
 
+       icmp_param = from;
+
        csum = skb_copy_and_csum_bits(icmp_param->skb,
                                      icmp_param->offset + offset,
                                      to, len);
@@ -413,7 +418,7 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
        int type = icmp_param->data.icmph.type;
        int code = icmp_param->data.icmph.code;
 
-       if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb))
+       if (ip_options_echo(net, &icmp_param->replyopts.opt, skb))
                return;
 
        /* Needed by both icmpv4_global_allow and icmp_xmit_lock */
@@ -435,10 +440,10 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
        daddr = ipc.addr = ip_hdr(skb)->saddr;
        saddr = fib_compute_spec_dst(skb);
 
-       if (icmp_param->replyopts.opt.opt.optlen) {
-               ipc.opt = &icmp_param->replyopts.opt;
+       if (icmp_param->replyopts.opt.optlen) {
+               ipc.opt = &icmp_param->replyopts;
                if (ipc.opt->opt.srr)
-                       daddr = icmp_param->replyopts.opt.opt.faddr;
+                       daddr = icmp_param->replyopts.opt.faddr;
        }
        memset(&fl4, 0, sizeof(fl4));
        fl4.daddr = daddr;
@@ -491,8 +496,8 @@ static struct rtable *icmp_route_lookup(struct net *net, struct flowi4 *fl4,
        int err;
 
        memset(fl4, 0, sizeof(*fl4));
-       fl4->daddr = (param->replyopts.opt.opt.srr ?
-                     param->replyopts.opt.opt.faddr : iph->saddr);
+       fl4->daddr = (param->replyopts.opt.srr ?
+                     param->replyopts.opt.faddr : iph->saddr);
        fl4->saddr = saddr;
        fl4->flowi4_mark = mark;
        fl4->flowi4_uid = sock_net_uid(net, NULL);
@@ -775,9 +780,10 @@ free_skb:
 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
                 const struct inet_skb_parm *parm)
 {
+       DEFINE_RAW_FLEX(struct icmp_bxm, icmp_param, replyopts.opt.__data,
+                       IP_OPTIONS_DATA_FIXED_SIZE);
        struct iphdr *iph;
        int room;
-       struct icmp_bxm icmp_param;
        struct rtable *rt = skb_rtable(skb_in);
        bool apply_ratelimit = false;
        struct sk_buff *ext_skb;
@@ -906,7 +912,7 @@ void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
                                           iph->tos;
        mark = IP4_REPLY_MARK(net, skb_in->mark);
 
-       if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in,
+       if (__ip_options_echo(net, &icmp_param->replyopts.opt, skb_in,
                              &parm->opt))
                goto out_unlock;
 
@@ -915,21 +921,21 @@ void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
         *      Prepare data for ICMP header.
         */
 
-       icmp_param.data.icmph.type       = type;
-       icmp_param.data.icmph.code       = code;
-       icmp_param.data.icmph.un.gateway = info;
-       icmp_param.data.icmph.checksum   = 0;
-       icmp_param.skb    = skb_in;
-       icmp_param.offset = skb_network_offset(skb_in);
+       icmp_param->data.icmph.type      = type;
+       icmp_param->data.icmph.code      = code;
+       icmp_param->data.icmph.un.gateway = info;
+       icmp_param->data.icmph.checksum  = 0;
+       icmp_param->skb   = skb_in;
+       icmp_param->offset = skb_network_offset(skb_in);
        ipcm_init(&ipc);
        ipc.tos = tos;
        ipc.addr = iph->saddr;
-       ipc.opt = &icmp_param.replyopts.opt;
+       ipc.opt = &icmp_param->replyopts;
        ipc.sockc.mark = mark;
 
        rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr,
                               inet_dsfield_to_dscp(tos), mark, type, code,
-                              &icmp_param);
+                              icmp_param);
        if (IS_ERR(rt))
                goto out_unlock;
 
@@ -942,7 +948,7 @@ void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
        room = dst_mtu(&rt->dst);
        if (room > 576)
                room = 576;
-       room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
+       room -= sizeof(struct iphdr) + icmp_param->replyopts.opt.optlen;
        room -= sizeof(struct icmphdr);
        /* Guard against tiny mtu. We need to include at least one
         * IP network header for this message to make any sense.
@@ -950,15 +956,15 @@ void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
        if (room <= (int)sizeof(struct iphdr))
                goto ende;
 
-       ext_skb = icmp_ext_append(net, skb_in, &icmp_param.data.icmph, room,
+       ext_skb = icmp_ext_append(net, skb_in, &icmp_param->data.icmph, room,
                                  parm->iif);
        if (ext_skb)
-               icmp_param.skb = ext_skb;
+               icmp_param->skb = ext_skb;
 
-       icmp_param.data_len = icmp_param.skb->len - icmp_param.offset;
-       if (icmp_param.data_len > room)
-               icmp_param.data_len = room;
-       icmp_param.head_len = sizeof(struct icmphdr);
+       icmp_param->data_len = icmp_param->skb->len - icmp_param->offset;
+       if (icmp_param->data_len > room)
+               icmp_param->data_len = room;
+       icmp_param->head_len = sizeof(struct icmphdr);
 
        /* if we don't have a source address at this point, fall back to the
         * dummy address instead of sending out a packet with a source address
@@ -969,7 +975,7 @@ void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
 
        trace_icmp_send(skb_in, type, code);
 
-       icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt);
+       icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt);
 
        if (ext_skb)
                consume_skb(ext_skb);
@@ -1206,7 +1212,8 @@ static enum skb_drop_reason icmp_redirect(struct sk_buff *skb)
 
 static enum skb_drop_reason icmp_echo(struct sk_buff *skb)
 {
-       struct icmp_bxm icmp_param;
+       DEFINE_RAW_FLEX(struct icmp_bxm, icmp_param, replyopts.opt.__data,
+                       IP_OPTIONS_DATA_FIXED_SIZE);
        struct net *net;
 
        net = skb_dst_dev_net_rcu(skb);
@@ -1214,18 +1221,18 @@ static enum skb_drop_reason icmp_echo(struct sk_buff *skb)
        if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all))
                return SKB_NOT_DROPPED_YET;
 
-       icmp_param.data.icmph      = *icmp_hdr(skb);
-       icmp_param.skb             = skb;
-       icmp_param.offset          = 0;
-       icmp_param.data_len        = skb->len;
-       icmp_param.head_len        = sizeof(struct icmphdr);
+       icmp_param->data.icmph     = *icmp_hdr(skb);
+       icmp_param->skb            = skb;
+       icmp_param->offset         = 0;
+       icmp_param->data_len       = skb->len;
+       icmp_param->head_len       = sizeof(struct icmphdr);
 
-       if (icmp_param.data.icmph.type == ICMP_ECHO)
-               icmp_param.data.icmph.type = ICMP_ECHOREPLY;
-       else if (!icmp_build_probe(skb, &icmp_param.data.icmph))
+       if (icmp_param->data.icmph.type == ICMP_ECHO)
+               icmp_param->data.icmph.type = ICMP_ECHOREPLY;
+       else if (!icmp_build_probe(skb, &icmp_param->data.icmph))
                return SKB_NOT_DROPPED_YET;
 
-       icmp_reply(&icmp_param, skb);
+       icmp_reply(icmp_param, skb);
        return SKB_NOT_DROPPED_YET;
 }
 
@@ -1353,7 +1360,8 @@ EXPORT_SYMBOL_GPL(icmp_build_probe);
  */
 static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb)
 {
-       struct icmp_bxm icmp_param;
+       DEFINE_RAW_FLEX(struct icmp_bxm, icmp_param, replyopts.opt.__data,
+                       IP_OPTIONS_DATA_FIXED_SIZE);
        /*
         *      Too short.
         */
@@ -1363,19 +1371,19 @@ static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb)
        /*
         *      Fill in the current time as ms since midnight UT:
         */
-       icmp_param.data.times[1] = inet_current_timestamp();
-       icmp_param.data.times[2] = icmp_param.data.times[1];
-
-       BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4));
-
-       icmp_param.data.icmph      = *icmp_hdr(skb);
-       icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
-       icmp_param.data.icmph.code = 0;
-       icmp_param.skb             = skb;
-       icmp_param.offset          = 0;
-       icmp_param.data_len        = 0;
-       icmp_param.head_len        = sizeof(struct icmphdr) + 12;
-       icmp_reply(&icmp_param, skb);
+       icmp_param->data.times[1] = inet_current_timestamp();
+       icmp_param->data.times[2] = icmp_param->data.times[1];
+
+       BUG_ON(skb_copy_bits(skb, 0, &icmp_param->data.times[0], 4));
+
+       icmp_param->data.icmph     = *icmp_hdr(skb);
+       icmp_param->data.icmph.type = ICMP_TIMESTAMPREPLY;
+       icmp_param->data.icmph.code = 0;
+       icmp_param->skb            = skb;
+       icmp_param->offset         = 0;
+       icmp_param->data_len       = 0;
+       icmp_param->head_len       = sizeof(struct icmphdr) + 12;
+       icmp_reply(icmp_param, skb);
        return SKB_NOT_DROPPED_YET;
 
 out_err:

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index ff11d3a85a3628fbde72d1657b6b6124981ac614..75fcb58795bbbd97d9544c05b245675ad1d1383a 100644 (file)
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1606,7 +1606,8 @@ void ip_send_unicast_reply(struct sock *sk, const struct sock *orig_sk,
                           const struct ip_reply_arg *arg,
                           unsigned int len, u64 transmit_time, u32 txhash)
 {
-       struct ip_options_data replyopts;
+       DEFINE_RAW_FLEX(struct ip_options_rcu, replyopts, opt.__data,
+                       IP_OPTIONS_DATA_FIXED_SIZE);
        struct ipcm_cookie ipc;
        struct flowi4 fl4;
        struct rtable *rt = skb_rtable(skb);
@@ -1615,18 +1616,18 @@ void ip_send_unicast_reply(struct sock *sk, const struct sock *orig_sk,
        int err;
        int oif;
 
-       if (__ip_options_echo(net, &replyopts.opt.opt, skb, sopt))
+       if (__ip_options_echo(net, &replyopts->opt, skb, sopt))
                return;
 
        ipcm_init(&ipc);
        ipc.addr = daddr;
        ipc.sockc.transmit_time = transmit_time;
 
-       if (replyopts.opt.opt.optlen) {
-               ipc.opt = &replyopts.opt;
+       if (replyopts->opt.optlen) {
+               ipc.opt = replyopts;
 
-               if (replyopts.opt.opt.srr)
-                       daddr = replyopts.opt.opt.faddr;
+               if (replyopts->opt.srr)
+                       daddr = replyopts->opt.faddr;
        }
 
        oif = arg->bound_dev_if;

diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index ad56588107cc8fb15fa1ff3d56046239a88781e3..7e2812668350eec5f41948594904d3050eb70b3b 100644 (file)
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -690,6 +690,8 @@ EXPORT_IPV6_MOD_GPL(ping_common_sendmsg);
 
 static int ping_v4_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 {
+       DEFINE_RAW_FLEX(struct ip_options_rcu, opt_copy, opt.__data,
+                       IP_OPTIONS_DATA_FIXED_SIZE);
        struct net *net = sock_net(sk);
        struct flowi4 fl4;
        struct inet_sock *inet = inet_sk(sk);
@@ -697,7 +699,6 @@ static int ping_v4_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
        struct icmphdr user_icmph;
        struct pingfakehdr pfh;
        struct rtable *rt = NULL;
-       struct ip_options_data opt_copy;
        int free = 0;
        __be32 saddr, daddr, faddr;
        u8 scope;
@@ -746,9 +747,9 @@ static int ping_v4_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
                rcu_read_lock();
                inet_opt = rcu_dereference(inet->inet_opt);
                if (inet_opt) {
-                       memcpy(&opt_copy, inet_opt,
+                       memcpy(opt_copy, inet_opt,
                               sizeof(*inet_opt) + inet_opt->opt.optlen);
-                       ipc.opt = &opt_copy.opt;
+                       ipc.opt = opt_copy;
                }
                rcu_read_unlock();
        }

diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 5998c4cc6f47b39f343cb1b0a9bd688b9d150281..e20c41206e29d5655f5378f08fb283f2ecbd2097 100644 (file)
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -481,6 +481,8 @@ static int raw_getfrag(void *from, char *to, int offset, int len, int odd,
 
 static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 {
+       DEFINE_RAW_FLEX(struct ip_options_rcu, opt_copy, opt.__data,
+                       IP_OPTIONS_DATA_FIXED_SIZE);
        struct inet_sock *inet = inet_sk(sk);
        struct net *net = sock_net(sk);
        struct ipcm_cookie ipc;
@@ -491,7 +493,6 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
        __be32 daddr;
        __be32 saddr;
        int uc_index, err;
-       struct ip_options_data opt_copy;
        struct raw_frag_vec rfv;
        int hdrincl;
 
@@ -561,9 +562,9 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
                rcu_read_lock();
                inet_opt = rcu_dereference(inet->inet_opt);
                if (inet_opt) {
-                       memcpy(&opt_copy, inet_opt,
+                       memcpy(opt_copy, inet_opt,
                               sizeof(*inet_opt) + inet_opt->opt.optlen);
-                       ipc.opt = &opt_copy.opt;
+                       ipc.opt = opt_copy;
                }
                rcu_read_unlock();
        }

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index ffe074cb58658741f3cf2037cff9ea79e7f92742..591527ae811cc37e303cef81b61f96d59db3c4ba 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1269,6 +1269,8 @@ EXPORT_IPV6_MOD_GPL(udp_cmsg_send);
 
 int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 {
+       DEFINE_RAW_FLEX(struct ip_options_rcu, opt_copy, opt.__data,
+                       IP_OPTIONS_DATA_FIXED_SIZE);
        struct inet_sock *inet = inet_sk(sk);
        struct udp_sock *up = udp_sk(sk);
        DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name);
@@ -1286,7 +1288,6 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
        int corkreq = udp_test_bit(CORK, sk) || msg->msg_flags & MSG_MORE;
        int (*getfrag)(void *, char *, int, int, int, struct sk_buff *);
        struct sk_buff *skb;
-       struct ip_options_data opt_copy;
        int uc_index;
 
        if (len > 0xFFFF)
@@ -1368,9 +1369,9 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
                rcu_read_lock();
                inet_opt = rcu_dereference(inet->inet_opt);
                if (inet_opt) {
-                       memcpy(&opt_copy, inet_opt,
+                       memcpy(opt_copy, inet_opt,
                               sizeof(*inet_opt) + inet_opt->opt.optlen);
-                       ipc.opt = &opt_copy.opt;
+                       ipc.opt = opt_copy;
                }
                rcu_read_unlock();
        }