ipv6: fix ndisc_is_useropt() handling for PIO

[ Upstream commit a46c68debf3be3a477a69ccbf0a1d050df841676 ]

The current logic only works if the PIO is between two
other ND user options.  This fixes it so that the PIO
can also be either before or after other ND user options
(for example the first or last option in the RA).

side note: there's actually Android tests verifying
a portion of the old broken behaviour, so:
  https://android-review.googlesource.com/c/kernel/tests/+/3196704
fixes those up.

Cc: Jen Linkova <furry@google.com>
Cc: Lorenzo Colitti <lorenzo@google.com>
Cc: Patrick Rohr <prohr@google.com>
Cc: David Ahern <dsahern@kernel.org>
Cc: YOSHIFUJI Hideaki / 吉藤英明 <yoshfuji@linux-ipv6.org>
Cc: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Fixes: 048c796beb6e ("ipv6: adjust ndisc_is_useropt() to also return true for PIO")
Link: https://patch.msgid.link/20240730001748.147636-1-maze@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index d914b23256ce6372cc764236edcf224273f5257a..0282d157250955eb1344ec8cac17d920a2f8383a 100644 (file)
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -227,6 +227,7 @@ struct ndisc_options *ndisc_parse_options(const struct net_device *dev,
                return NULL;
        memset(ndopts, 0, sizeof(*ndopts));
        while (opt_len) {
+               bool unknown = false;
                int l;
                if (opt_len < sizeof(struct nd_opt_hdr))
                        return NULL;
@@ -262,22 +263,23 @@ struct ndisc_options *ndisc_parse_options(const struct net_device *dev,
                        break;
 #endif
                default:
-                       if (ndisc_is_useropt(dev, nd_opt)) {
-                               ndopts->nd_useropts_end = nd_opt;
-                               if (!ndopts->nd_useropts)
-                                       ndopts->nd_useropts = nd_opt;
-                       } else {
-                               /*
-                                * Unknown options must be silently ignored,
-                                * to accommodate future extension to the
-                                * protocol.
-                                */
-                               ND_PRINTK(2, notice,
-                                         "%s: ignored unsupported option; type=%d, len=%d\n",
-                                         __func__,
-                                         nd_opt->nd_opt_type,
-                                         nd_opt->nd_opt_len);
-                       }
+                       unknown = true;
+               }
+               if (ndisc_is_useropt(dev, nd_opt)) {
+                       ndopts->nd_useropts_end = nd_opt;
+                       if (!ndopts->nd_useropts)
+                               ndopts->nd_useropts = nd_opt;
+               } else if (unknown) {
+                       /*
+                        * Unknown options must be silently ignored,
+                        * to accommodate future extension to the
+                        * protocol.
+                        */
+                       ND_PRINTK(2, notice,
+                                 "%s: ignored unsupported option; type=%d, len=%d\n",
+                                 __func__,
+                                 nd_opt->nd_opt_type,
+                                 nd_opt->nd_opt_len);
                }
 next_opt:
                opt_len -= l;