ipv4: igmp: convert ip_mc_msfget() to sockopt_t

Browse source

IP_MSFILTER reads its reply through ip_mc_msfget(), reached from
do_ip_getsockopt() and from nowhere else. Convert it, and build the
sockopt_t at the call site for as long as the caller still carries a
sockptr_t pair.

optlen here only has to cover the header, and the real reply size comes
from the imsf_numsrc field inside it. This is nasty, but userspace
relies on it, so sockopt_expand_out() preserves the same mechanism: it
grows optval only for a user address, and assumes the caller left room
for the size its own header asked for.

The *optlen store moves out of ip_mc_msfget() and into the call site,
guarded by !err so the -EINVAL, -ENODEV and -EADDRNOTAVAIL returns still
leave the caller's optlen word untouched.

The source list also moves from copy_to_sockptr_offset() to a sequential
copy_to_iter(). IP_MSFILTER_SIZE(0) and offsetof(struct ip_msfilter,
imsf_slist_flex) are both 16, so the bytes land where they did.

Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20260914-getsockopt_phase6-v2-2-e48befc9602e@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

...

This commit is contained in:

Breno Leitao 2026-09-14 05:20:08 -07:00 • committed by Jakub Kicinski

parent 0093f7db9c

commit e12e04f5ab

3 changed files with 25 additions and 11 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

3

include/linux/igmp.h

View file

23

net/ipv4/igmp.c

View file

10

net/ipv4/ip_sockglue.c

View file