kernel/linux.git/include/net/genetlink.h, branch v6.6.131

genetlink: hold RCU in genlmsg_mcast()

2024-11-01T00:58:23+00:00

[ Upstream commit 56440d7ec28d60f8da3bfa09062b3368ff9b16db ] While running net selftests with CONFIG_PROVE_RCU_LIST=y I saw one lockdep splat [1]. genlmsg_mcast() uses for_each_net_rcu(), and must therefore hold RCU. Instead of letting all callers guard genlmsg_multicast_allns() with a rcu_read_lock()/rcu_read_unlock() pair, do it in genlmsg_mcast(). This also means the @flags parameter is useless, we need to always use GFP_ATOMIC. [1] [10882.424136] ============================= [10882.424166] WARNING: suspicious RCU usage [10882.424309] 6.12.0-rc2-virtme #1156 Not tainted [10882.424400] ----------------------------- [10882.424423] net/netlink/genetlink.c:1940 RCU-list traversed in non-reader section!! [10882.424469] other info that might help us debug this: [10882.424500] rcu_scheduler_active = 2, debug_locks = 1 [10882.424744] 2 locks held by ip/15677: [10882.424791] #0: ffffffffb6b491b0 (cb_lock){++++}-{3:3}, at: genl_rcv (net/netlink/genetlink.c:1219) [10882.426334] #1: ffffffffb6b49248 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg (net/netlink/genetlink.c:61 net/netlink/genetlink.c:57 net/netlink/genetlink.c:1209) [10882.426465] stack backtrace: [10882.426805] CPU: 14 UID: 0 PID: 15677 Comm: ip Not tainted 6.12.0-rc2-virtme #1156 [10882.426919] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [10882.427046] Call Trace: [10882.427131] [10882.427244] dump_stack_lvl (lib/dump_stack.c:123) [10882.427335] lockdep_rcu_suspicious (kernel/locking/lockdep.c:6822) [10882.427387] genlmsg_multicast_allns (net/netlink/genetlink.c:1940 (discriminator 7) net/netlink/genetlink.c:1977 (discriminator 7)) [10882.427436] l2tp_tunnel_notify.constprop.0 (net/l2tp/l2tp_netlink.c:119) l2tp_netlink [10882.427683] l2tp_nl_cmd_tunnel_create (net/l2tp/l2tp_netlink.c:253) l2tp_netlink [10882.427748] genl_family_rcv_msg_doit (net/netlink/genetlink.c:1115) [10882.427834] genl_rcv_msg (net/netlink/genetlink.c:1195 net/netlink/genetlink.c:1210) [10882.427877] ? __pfx_l2tp_nl_cmd_tunnel_create (net/l2tp/l2tp_netlink.c:186) l2tp_netlink [10882.427927] ? __pfx_genl_rcv_msg (net/netlink/genetlink.c:1201) [10882.427959] netlink_rcv_skb (net/netlink/af_netlink.c:2551) [10882.428069] genl_rcv (net/netlink/genetlink.c:1220) [10882.428095] netlink_unicast (net/netlink/af_netlink.c:1332 net/netlink/af_netlink.c:1357) [10882.428140] netlink_sendmsg (net/netlink/af_netlink.c:1901) [10882.428210] ____sys_sendmsg (net/socket.c:729 (discriminator 1) net/socket.c:744 (discriminator 1) net/socket.c:2607 (discriminator 1)) Fixes: 33f72e6f0c67 ("l2tp : multicast notification to the registered listeners") Signed-off-by: Eric Dumazet Cc: James Chapman Cc: Tom Parkin Cc: Johannes Berg Link: https://patch.msgid.link/20241011171217.3166614-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

drop_monitor: Require 'CAP_SYS_ADMIN' when joining "events" group

2023-12-13T17:45:10+00:00

[ Upstream commit e03781879a0d524ce3126678d50a80484a513c4b ] The "NET_DM" generic netlink family notifies drop locations over the "events" multicast group. This is problematic since by default generic netlink allows non-root users to listen to these notifications. Fix by adding a new field to the generic netlink multicast group structure that when set prevents non-root users or root without the 'CAP_SYS_ADMIN' capability (in the user namespace owning the network namespace) from joining the group. Set this field for the "events" group. Use 'CAP_SYS_ADMIN' rather than 'CAP_NET_ADMIN' because of the nature of the information that is shared over this group. Note that the capability check in this case will always be performed against the initial user namespace since the family is not netns aware and only operates in the initial network namespace. A new field is added to the structure rather than using the "flags" field because the existing field uses uAPI flags and it is inappropriate to add a new uAPI flag for an internal kernel check. In net-next we can rework the "flags" field to use internal flags and fold the new field into it. But for now, in order to reduce the amount of changes, add a new field. Since the information can only be consumed by root, mark the control plane operations that start and stop the tracing as root-only using the 'GENL_ADMIN_PERM' flag. Tested using [1]. Before: # capsh -- -c ./dm_repo # capsh --drop=cap_sys_admin -- -c ./dm_repo After: # capsh -- -c ./dm_repo # capsh --drop=cap_sys_admin -- -c ./dm_repo Failed to join "events" multicast group [1] $ cat dm.c #include #include #include #include int main(int argc, char **argv) { struct nl_sock *sk; int grp, err; sk = nl_socket_alloc(); if (!sk) { fprintf(stderr, "Failed to allocate socket\n"); return -1; } err = genl_connect(sk); if (err) { fprintf(stderr, "Failed to connect socket\n"); return err; } grp = genl_ctrl_resolve_grp(sk, "NET_DM", "events"); if (grp < 0) { fprintf(stderr, "Failed to resolve \"events\" multicast group\n"); return grp; } err = nl_socket_add_memberships(sk, grp, NFNLGRP_NONE); if (err) { fprintf(stderr, "Failed to join \"events\" multicast group\n"); return err; } return 0; } $ gcc -I/usr/include/libnl3 -lnl-3 -lnl-genl-3 -o dm_repo dm.c Fixes: 9a8afc8d3962 ("Network Drop Monitor: Adding drop monitor implementation & Netlink protocol") Reported-by: "The UK's National Cyber Security Centre (NCSC)" Signed-off-by: Ido Schimmel Reviewed-by: Jacob Keller Reviewed-by: Jiri Pirko Link: https://lore.kernel.org/r/20231206213102.1824398-3-idosch@nvidia.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

genetlink: add genlmsg_iput() API

2023-08-15T22:01:03+00:00

Add some APIs and helpers required for convenient construction of replies and notifications based on struct genl_info. Reviewed-by: Jiri Pirko Link: https://lore.kernel.org/r/20230814214723.2924989-8-kuba@kernel.org Signed-off-by: Jakub Kicinski

genetlink: add a family pointer to struct genl_info

2023-08-15T22:01:03+00:00

Having family in struct genl_info is quite useful. It cuts down the number of arguments which need to be passed to helpers which already take struct genl_info. Reviewed-by: Jiri Pirko Link: https://lore.kernel.org/r/20230814214723.2924989-7-kuba@kernel.org Signed-off-by: Jakub Kicinski

genetlink: use attrs from struct genl_info

2023-08-15T22:00:45+00:00

Since dumps carry struct genl_info now, use the attrs pointer from genl_info and remove the one in struct genl_dumpit_info. Reviewed-by: Johannes Berg Reviewed-by: Miquel Raynal Reviewed-by: Jiri Pirko Link: https://lore.kernel.org/r/20230814214723.2924989-6-kuba@kernel.org Signed-off-by: Jakub Kicinski

genetlink: add struct genl_info to struct genl_dumpit_info

2023-08-15T21:54:44+00:00

Netlink GET implementations must currently juggle struct genl_info and struct netlink_callback, depending on whether they were called from doit or dumpit. Add genl_info to the dump state and populate the fields. This way implementations can simply pass struct genl_info around. Reviewed-by: Jiri Pirko Link: https://lore.kernel.org/r/20230814214723.2924989-5-kuba@kernel.org Signed-off-by: Jakub Kicinski

genetlink: remove userhdr from struct genl_info

2023-08-15T21:54:44+00:00

Only three families use info->userhdr today and going forward we discourage using fixed headers in new families. So having the pointer to user header in struct genl_info is an overkill. Compute the header pointer at runtime. Reviewed-by: Johannes Berg Reviewed-by: Jiri Pirko Reviewed-by: Aaron Conole Link: https://lore.kernel.org/r/20230814214723.2924989-4-kuba@kernel.org Signed-off-by: Jakub Kicinski

genetlink: make genl_info->nlhdr const

2023-08-15T21:54:44+00:00

struct netlink_callback has a const nlh pointer, make the pointer in struct genl_info const as well, to make copying between the two easier. Reviewed-by: Jiri Pirko Link: https://lore.kernel.org/r/20230814214723.2924989-3-kuba@kernel.org Signed-off-by: Jakub Kicinski

mptcp: more detailed error reporting on endpoint creation

2022-11-21T13:09:07+00:00

Endpoint creation can fail for a number of reasons; in case of failure append the error number to the extended ack message, using a newly introduced generic helper. Additionally let mptcp_pm_nl_append_new_local_addr() report different error reasons. Reviewed-by: Mat Martineau Signed-off-by: Paolo Abeni Signed-off-by: Mat Martineau Signed-off-by: David S. Miller

genetlink: allow families to use split ops directly

2022-11-07T12:30:17+00:00

Let families to hook in the new split ops. They are more flexible and should not be much larger than full ops. Each split op is 40B while full op is 48B. Devlink for example has 54 dos and 19 dumps, 2 of the dumps do not have a do -> 56 full commands = 2688B. Split ops would have taken 2920B, so 9% more space while allowing individual per/post doit and per-type policies. Signed-off-by: Jakub Kicinski Reviewed-by: Jacob Keller Signed-off-by: David S. Miller