lwn.git/net/netlink, branch docs-6.9

genetlink: Use internal flags for multicast groups

2023-12-29T08:43:59+00:00

As explained in commit e03781879a0d ("drop_monitor: Require 'CAP_SYS_ADMIN' when joining "events" group"), the "flags" field in the multicast group structure reuses uAPI flags despite the field not being exposed to user space. This makes it impossible to extend its use without adding new uAPI flags, which is inappropriate for internal kernel checks. Solve this by adding internal flags (i.e., "GENL_MCAST_*") and convert the existing users to use them instead of the uAPI flags. Tested using the reproducers in commit 44ec98ea5ea9 ("psample: Require 'CAP_NET_ADMIN' when joining "packets" group") and commit e03781879a0d ("drop_monitor: Require 'CAP_SYS_ADMIN' when joining "events" group"). No functional changes intended. Signed-off-by: Ido Schimmel Reviewed-by: Mat Martineau Reviewed-by: Andy Shevchenko Signed-off-by: David S. Miller

netlink: introduce typedef for filter function

2023-12-19T14:31:40+00:00

Make the code using filter function a bit nicer by consolidating the filter function arguments using typedef. Suggested-by: Andy Shevchenko Signed-off-by: Jiri Pirko Signed-off-by: Paolo Abeni

genetlink: introduce per-sock family private storage

2023-12-19T14:31:40+00:00

Introduce an xarray for Generic netlink family to store per-socket private. Initialize this xarray only if family uses per-socket privs. Introduce genl_sk_priv_get() to get the socket priv pointer for a family and initialize it in case it does not exist. Introduce __genl_sk_priv_get() to obtain socket priv pointer for a family under RCU read lock. Allow family to specify the priv size, init() and destroy() callbacks. Signed-off-by: Jiri Pirko Signed-off-by: Paolo Abeni

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2023-12-08T01:53:17+00:00

Cross-merge networking fixes after downstream PR. Conflicts: drivers/net/ethernet/stmicro/stmmac/dwmac5.c drivers/net/ethernet/stmicro/stmmac/dwmac5.h drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c drivers/net/ethernet/stmicro/stmmac/hwif.h 37e4b8df27bc ("net: stmmac: fix FPE events losing") c3f3b97238f6 ("net: stmmac: Refactor EST implementation") https://lore.kernel.org/all/20231206110306.01e91114@canb.auug.org.au/ Adjacent changes: net/ipv4/tcp_ao.c 9396c4ee93f9 ("net/tcp: Don't store TCP-AO maclen on reqsk") 7b0f570f879a ("tcp: Move TCP-AO bits from cookie_v[46]_check() to tcp_ao_syncookie().") Signed-off-by: Jakub Kicinski

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

2023-12-07T17:54:02+00:00

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

rtnetlink: introduce nlmsg_new_large and use it in rtnl_getlink

2023-11-19T04:18:25+00:00

if a PF has 256 or more VFs, ip link command will allocate an order 3 memory or more, and maybe trigger OOM due to memory fragment, the VFs needed memory size is computed in rtnl_vfinfo_size. so introduce nlmsg_new_large which calls netlink_alloc_large_skb in which vmalloc is used for large memory, to avoid the failure of allocating memory ip invoked oom-killer: gfp_mask=0xc2cc0(GFP_KERNEL|__GFP_NOWARN|\ __GFP_COMP|__GFP_NOMEMALLOC), order=3, oom_score_adj=0 CPU: 74 PID: 204414 Comm: ip Kdump: loaded Tainted: P OE Call Trace: dump_stack+0x57/0x6a dump_header+0x4a/0x210 oom_kill_process+0xe4/0x140 out_of_memory+0x3e8/0x790 __alloc_pages_slowpath.constprop.116+0x953/0xc50 __alloc_pages_nodemask+0x2af/0x310 kmalloc_large_node+0x38/0xf0 __kmalloc_node_track_caller+0x417/0x4d0 __kmalloc_reserve.isra.61+0x2e/0x80 __alloc_skb+0x82/0x1c0 rtnl_getlink+0x24f/0x370 rtnetlink_rcv_msg+0x12c/0x350 netlink_rcv_skb+0x50/0x100 netlink_unicast+0x1b2/0x280 netlink_sendmsg+0x355/0x4a0 sock_sendmsg+0x5b/0x60 ____sys_sendmsg+0x1ea/0x250 ___sys_sendmsg+0x88/0xd0 __sys_sendmsg+0x5e/0xa0 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f95a65a5b70 Cc: Yunsheng Lin Signed-off-by: Li RongQing Link: https://lore.kernel.org/r/20231115120108.3711-1-lirongqing@baidu.com Signed-off-by: Jakub Kicinski

netlink: fill in missing MODULE_DESCRIPTION()

2023-11-03T11:42:48+00:00

W=1 builds now warn if a module is built without a MODULE_DESCRIPTION(). Fill it in for sock_diag. Signed-off-by: Jakub Kicinski Signed-off-by: David S. Miller

genetlink: don't merge dumpit split op for different cmds into single iter

2023-10-23T23:11:53+00:00

Currently, split ops of doit and dumpit are merged into a single iter item when they are subsequent. However, there is no guarantee that the dumpit op is for the same cmd as doit op. Fix this by checking if cmd is the same for both. This problem does not occur in existing families. Signed-off-by: Jiri Pirko Reviewed-by: Jacob Keller Link: https://lore.kernel.org/r/20231021112711.660606-2-jiri@resnulli.us Signed-off-by: Jakub Kicinski

netlink: add variable-length / auto integers

2023-10-20T10:43:35+00:00

We currently push everyone to use padding to align 64b values in netlink. Un-padded nla_put_u64() doesn't even exist any more. The story behind this possibly start with this thread: https://lore.kernel.org/netdev/20121204.130914.1457976839967676240.davem@davemloft.net/ where DaveM was concerned about the alignment of a structure containing 64b stats. If user space tries to access such struct directly: struct some_stats *stats = nla_data(attr); printf("A: %llu", stats->a); lack of alignment may become problematic for some architectures. These days we most often put every single member in a separate attribute, meaning that the code above would use a helper like nla_get_u64(), which can deal with alignment internally. Even for arches which don't have good unaligned access - access aligned to 4B should be pretty efficient. Kernel and well known libraries deal with unaligned input already. Padded 64b is quite space-inefficient (64b + pad means at worst 16B per attr vs 32b which takes 8B). It is also more typing: if (nla_put_u64_pad(rsp, NETDEV_A_SOMETHING_SOMETHING, value, NETDEV_A_SOMETHING_PAD)) Create a new attribute type which will use 32 bits at netlink level if value is small enough (probably most of the time?), and (4B-aligned) 64 bits otherwise. Kernel API is just: if (nla_put_uint(rsp, NETDEV_A_SOMETHING_SOMETHING, value)) Calling this new type "just" sint / uint with no specific size will hopefully also make people more comfortable with using it. Currently telling people "don't use u8, you may need the bits, and netlink will round up to 4B, anyway" is the #1 comment we give to newcomers. In terms of netlink layout it looks like this: 0 4 8 12 16 32b: [nlattr][ u32 ] 64b: [ pad ][nlattr][ u64 ] uint(32) [nlattr][ u32 ] uint(64) [nlattr][ u64 ] Signed-off-by: Jakub Kicinski Acked-by: Nicolas Dichtel Signed-off-by: David S. Miller

netlink: Annotate struct netlink_policy_dump_state with __counted_by

2023-10-06T09:48:46+00:00

Prepare for the coming implementation by GCC and Clang of the __counted_by attribute. Flexible array members annotated with __counted_by can have their accesses bounds-checked at run-time via CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family functions). As found with Coccinelle[1], add __counted_by for struct netlink_policy_dump_state. Additionally update the size of the usage array length before accessing it. This requires remembering the old size for the memset() and later assignments. Cc: "David S. Miller" Cc: Eric Dumazet Cc: Jakub Kicinski Cc: Paolo Abeni Cc: Johannes Berg Cc: netdev@vger.kernel.org Link: https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci [1] Signed-off-by: Kees Cook Reviewed-by: Gustavo A. R. Silva Signed-off-by: David S. Miller