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ipv6: pass proto by value to ipv6_push_nfrag_opts() and ipv6_push_frag_opts()

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With CONFIG_STACKPROTECTOR_STRONG=y, it is better to avoid passing
a pointer to an automatic variable.

Change these exported functions to return 'u8 proto'
instead of void.

- ipv6_push_nfrag_opts()
- ipv6_push_frag_opts()

For instance, replace
	ipv6_push_frag_opts(skb, opt, &proto);
with:
	proto = ipv6_push_frag_opts(skb, opt, proto);

Note that even after this change, ip6_xmit() has to use a stack canary
because of @first_hop variable.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260130210303.3888261-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2026-01-30 21:02:56 +00:00 committed by Jakub Kicinski
parent e022155343
commit 1bc46dd209
4 changed files with 46 additions and 40 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
include/net/ipv6.h
View File

@ -1151,11 +1151,11 @@ int ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb);
* Extension header (options) processing
*/
void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
u8 *proto, struct in6_addr **daddr_p,
struct in6_addr *saddr);
void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
u8 *proto);
u8 ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
u8 proto, struct in6_addr **daddr_p,
struct in6_addr *saddr);
u8 ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
u8 proto);
int ipv6_skip_exthdr(const struct sk_buff *, int start, u8 *nexthdrp,
__be16 *frag_offp);

55
net/ipv6/exthdrs.c
View File

@ -1074,9 +1074,9 @@ int ipv6_parse_hopopts(struct sk_buff *skb)
* for headers.
*/
static void ipv6_push_rthdr0(struct sk_buff *skb, u8 *proto,
struct ipv6_rt_hdr *opt,
struct in6_addr **addr_p, struct in6_addr *saddr)
static u8 ipv6_push_rthdr0(struct sk_buff *skb, u8 proto,
struct ipv6_rt_hdr *opt,
struct in6_addr **addr_p, struct in6_addr *saddr)
{
struct rt0_hdr *phdr, *ihdr;
int hops;
@ -1095,13 +1095,13 @@ static void ipv6_push_rthdr0(struct sk_buff *skb, u8 *proto,
phdr->addr[hops - 1] = **addr_p;
*addr_p = ihdr->addr;
phdr->rt_hdr.nexthdr = *proto;
*proto = NEXTHDR_ROUTING;
phdr->rt_hdr.nexthdr = proto;
return NEXTHDR_ROUTING;
}
static void ipv6_push_rthdr4(struct sk_buff *skb, u8 *proto,
struct ipv6_rt_hdr *opt,
struct in6_addr **addr_p, struct in6_addr *saddr)
static u8 ipv6_push_rthdr4(struct sk_buff *skb, u8 proto,
struct ipv6_rt_hdr *opt,
struct in6_addr **addr_p, struct in6_addr *saddr)
{
struct ipv6_sr_hdr *sr_phdr, *sr_ihdr;
int plen, hops;
@ -1144,58 +1144,61 @@ static void ipv6_push_rthdr4(struct sk_buff *skb, u8 *proto,
}
#endif
sr_phdr->nexthdr = *proto;
*proto = NEXTHDR_ROUTING;
sr_phdr->nexthdr = proto;
return NEXTHDR_ROUTING;
}
static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
struct ipv6_rt_hdr *opt,
struct in6_addr **addr_p, struct in6_addr *saddr)
static u8 ipv6_push_rthdr(struct sk_buff *skb, u8 proto,
struct ipv6_rt_hdr *opt,
struct in6_addr **addr_p, struct in6_addr *saddr)
{
switch (opt->type) {
case IPV6_SRCRT_TYPE_0:
case IPV6_SRCRT_STRICT:
case IPV6_SRCRT_TYPE_2:
ipv6_push_rthdr0(skb, proto, opt, addr_p, saddr);
proto = ipv6_push_rthdr0(skb, proto, opt, addr_p, saddr);
break;
case IPV6_SRCRT_TYPE_4:
ipv6_push_rthdr4(skb, proto, opt, addr_p, saddr);
proto = ipv6_push_rthdr4(skb, proto, opt, addr_p, saddr);
break;
default:
break;
}
return proto;
}
static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt)
static u8 ipv6_push_exthdr(struct sk_buff *skb, u8 proto, u8 type, struct ipv6_opt_hdr *opt)
{
struct ipv6_opt_hdr *h = skb_push(skb, ipv6_optlen(opt));
memcpy(h, opt, ipv6_optlen(opt));
h->nexthdr = *proto;
*proto = type;
h->nexthdr = proto;
return type;
}
void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
u8 *proto,
struct in6_addr **daddr, struct in6_addr *saddr)
u8 ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
u8 proto,
struct in6_addr **daddr, struct in6_addr *saddr)
{
if (opt->srcrt) {
ipv6_push_rthdr(skb, proto, opt->srcrt, daddr, saddr);
proto = ipv6_push_rthdr(skb, proto, opt->srcrt, daddr, saddr);
/*
* IPV6_RTHDRDSTOPTS is ignored
* unless IPV6_RTHDR is set (RFC3542).
*/
if (opt->dst0opt)
ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt);
proto = ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt);
}
if (opt->hopopt)
ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt);
proto = ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt);
return proto;
}
void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto)
u8 ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 proto)
{
if (opt->dst1opt)
ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt);
proto = ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt);
return proto;
}
EXPORT_SYMBOL(ipv6_push_frag_opts);

19
net/ipv6/ip6_output.c
View File

@ -305,11 +305,12 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
seg_len += opt->opt_nflen + opt->opt_flen;
if (opt->opt_flen)
ipv6_push_frag_opts(skb, opt, &proto);
proto = ipv6_push_frag_opts(skb, opt, proto);
if (opt->opt_nflen)
ipv6_push_nfrag_opts(skb, opt, &proto, &first_hop,
&fl6->saddr);
proto = ipv6_push_nfrag_opts(skb, opt, proto,
&first_hop,
&fl6->saddr);
}
if (unlikely(seg_len > IPV6_MAXPLEN)) {
@ -1940,11 +1941,13 @@ struct sk_buff *__ip6_make_skb(struct sock *sk,
__skb_pull(skb, skb_network_header_len(skb));
final_dst = &fl6->daddr;
if (opt && opt->opt_flen)
ipv6_push_frag_opts(skb, opt, &proto);
if (opt && opt->opt_nflen)
ipv6_push_nfrag_opts(skb, opt, &proto, &final_dst, &fl6->saddr);
if (opt) {
if (opt->opt_flen)
proto = ipv6_push_frag_opts(skb, opt, proto);
if (opt->opt_nflen)
proto = ipv6_push_nfrag_opts(skb, opt, proto,
&final_dst, &fl6->saddr);
}
skb_push(skb, sizeof(struct ipv6hdr));
skb_reset_network_header(skb);
hdr = ipv6_hdr(skb);

2
net/ipv6/ip6_tunnel.c
View File

@ -1265,7 +1265,7 @@ int ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev, __u8 dsfield,
if (encap_limit >= 0) {
init_tel_txopt(&opt, encap_limit);
ipv6_push_frag_opts(skb, &opt.ops, &proto);
proto = ipv6_push_frag_opts(skb, &opt.ops, proto);
}
skb_push(skb, sizeof(struct ipv6hdr));