ipv6: fix ndisc_is_useropt() handling for PIO

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>

diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index 70a0b2ad6bd70c2d5152ab59d2834a63587e6652..b8eec1b6cc2c88bfbf66fec165a6a8782ffd8242 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;