"ip maddr show" prints link-layer, IPv4 and IPv6 entries. The IPv4 and IPv6 ones come over netlink today, with IFA_MC_USERS for the user count. The link-layer list, dev->mc, is only exported via /proc/net/dev_mcast, so iproute2 and other users still parse procfs for it.
This series adds the AF_PACKET family to RTM_GETMULTICAST so that the link-layer multicast addresses are reported the same way. Patch 2 dumps dev->mc in the ifaddrmsg format of the IPv4 and IPv6 dumps: IFA_MULTICAST carries the address, IFA_MC_USERS the reference count and a new IFA_F_GLOBAL flag marks entries added explicitly, the "static" column of /proc/net/dev_mcast. ifa_index limits the dump to one device and IFA_TARGET_NETNSID selects another netns. Patches 1 and 3 update the rt-addr spec and patch 4 adds a selftest. AF_PACKET dumps returned -EOPNOTSUPP before, so iproute2 can keep the procfs fallback for older kernels. The iproute2 side is ready and will be posted once this is in. Changes in v6: - Move the dump to net/core/dev_addr_lists.c next to the dev->mc helpers - Stamp cb->seq from dev_base_seq and check dump consistency - Let an unexpected dump error propagate instead of skipping - Check for an address only present in the peer netns in the target-netnsid selftest, the peer and local ifindex can be equal - Document the ifa-index filter and the zero header fields in the spec Changes in v5: - Filter the target-netnsid selftest dump by ifa-index, a new netns also contains the fallback tunnel devices Changes in v4: - Reset the resume offset when the device the dump stopped at is gone - Use a tracked netns reference (put_net_track) - Say ifa-family must be set in the spec doc, drop the AF_UNSPEC remark - Close the netlink socket and guard the checks in the selftest - Drop the Fixes tag Changes in v3: - Report the static bit as a new IFA_F_GLOBAL flag in IFA_FLAGS instead of IFA_F_PERMANENT - Support IFA_TARGET_NETNSID and test it - Describe global_use accurately, it is also set by dev_mc_add_excl() - Fix the target-netnsid type in the rt-addr spec, as its own patch Changes in v2: - Always validate the request header, not only with strict checking - Use a single "with" statement in the selftest (ruff) Yuyang Huang (4): netlink: specs: rt-addr: fix the type of target-netnsid net: add AF_PACKET multicast dumps netlink: specs: rt-addr: document AF_PACKET multicast dumps selftests: net: test AF_PACKET multicast dumps Documentation/netlink/specs/rt-addr.yaml | 19 ++- include/linux/netdevice.h | 1 + include/uapi/linux/if_addr.h | 1 + net/core/dev_addr_lists.c | 177 +++++++++++++++++++++++ net/core/rtnetlink.c | 2 + tools/testing/selftests/net/rtnetlink.py | 73 +++++++++- 6 files changed, 268 insertions(+), 5 deletions(-) -- 2.43.0
