kernel/linux.git/net/ipv4/fib_frontend.c, branch linux-7.1.y

ipv4: Convert ->flowi4_tos to dscp_t.

2025-08-27T00:34:31+00:00

Convert the ->flowic_tos field of struct flowi_common from __u8 to dscp_t, rename it ->flowic_dscp and propagate these changes to struct flowi and struct flowi4. We've had several bugs in the past where ECN bits could interfere with IPv4 routing, because these bits were not properly cleared when setting ->flowi4_tos. These bugs should be fixed now and the dscp_t type has been introduced to ensure that variables carrying DSCP values don't accidentally have any ECN bits set. Several variables and structure fields have been converted to dscp_t already, but the main IPv4 routing structure, struct flowi4, is still using a __u8. To avoid any future regression, this patch converts it to dscp_t. There are many users to convert at once. Fortunately, around half of ->flowi4_tos users already have a dscp_t value at hand, which they currently convert to __u8 using inet_dscp_to_dsfield(). For all of these users, we just need to drop that conversion. But, although we try to do the __u8 <-> dscp_t conversions at the boundaries of the network or of user space, some places still store TOS/DSCP variables as __u8 in core networking code. Those can hardly be converted either because the data structure is part of UAPI or because the same variable or field is also used for handling ECN in other parts of the code. In all of these cases where we don't have a dscp_t variable at hand, we need to use inet_dsfield_to_dscp() when interacting with ->flowi4_dscp. Changes since v1: * Fix space alignment in __bpf_redirect_neigh_v4() (Ido). Signed-off-by: Guillaume Nault Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/29acecb45e911d17446b9a3dbdb1ab7b821ea371.1756128932.git.gnault@redhat.com Signed-off-by: Jakub Kicinski

net: s/dev_get_flags/netif_get_flags/

2025-07-19T00:27:47+00:00

Commit cc34acd577f1 ("docs: net: document new locking reality") introduced netif_ vs dev_ function semantics: the former expects locked netdev, the latter takes care of the locking. We don't strictly follow this semantics on either side, but there are more dev_xxx handlers now that don't fit. Rename them to netif_xxx where appropriate. Signed-off-by: Stanislav Fomichev Link: https://patch.msgid.link/20250717172333.1288349-6-sdf@fomichev.me Signed-off-by: Jakub Kicinski

inet: Remove rtnl_is_held arg of lwtunnel_valid_encap_type(_attr)?().

2025-05-21T02:18:24+00:00

Commit f130a0cc1b4f ("inet: fix lwtunnel_valid_encap_type() lock imbalance") added the rtnl_is_held argument as a temporary fix while I'm converting nexthop and IPv6 routing table to per-netns RTNL or RCU. Now all callers of lwtunnel_valid_encap_type() do not hold RTNL. Let's remove the argument. Signed-off-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250516022759.44392-3-kuniyu@amazon.com Signed-off-by: Jakub Kicinski

ipv4: Use nlmsg_payload in fib_frontend file

2025-04-17T01:33:02+00:00

Leverage the new nlmsg_payload() helper to avoid checking for message size and then reading the nlmsg data. Signed-off-by: Breno Leitao Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250415-nlmsg_v2-v1-5-a1c75d493fd7@debian.org Signed-off-by: Jakub Kicinski

inet: fix lwtunnel_valid_encap_type() lock imbalance

2025-03-06T03:16:56+00:00

After blamed commit rtm_to_fib_config() now calls lwtunnel_valid_encap_type{_attr}() without RTNL held, triggering an unlock balance in __rtnl_unlock, as reported by syzbot [1] IPv6 and rtm_to_nh_config() are not yet converted. Add a temporary @rtnl_is_held parameter to lwtunnel_valid_encap_type() and lwtunnel_valid_encap_type_attr(). While we are at it replace the two rcu_dereference() in lwtunnel_valid_encap_type() with more appropriate rcu_access_pointer(). [1] syz-executor245/5836 is trying to release lock (rtnl_mutex) at: [] __rtnl_unlock+0x6c/0xf0 net/core/rtnetlink.c:142 but there are no more locks to release! other info that might help us debug this: no locks held by syz-executor245/5836. stack backtrace: CPU: 0 UID: 0 PID: 5836 Comm: syz-executor245 Not tainted 6.14.0-rc4-syzkaller-00873-g3424291dd242 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_unlock_imbalance_bug+0x25b/0x2d0 kernel/locking/lockdep.c:5289 __lock_release kernel/locking/lockdep.c:5518 [inline] lock_release+0x47e/0xa30 kernel/locking/lockdep.c:5872 __mutex_unlock_slowpath+0xec/0x800 kernel/locking/mutex.c:891 __rtnl_unlock+0x6c/0xf0 net/core/rtnetlink.c:142 lwtunnel_valid_encap_type+0x38a/0x5f0 net/core/lwtunnel.c:169 lwtunnel_valid_encap_type_attr+0x113/0x270 net/core/lwtunnel.c:209 rtm_to_fib_config+0x949/0x14e0 net/ipv4/fib_frontend.c:808 inet_rtm_newroute+0xf6/0x2a0 net/ipv4/fib_frontend.c:917 rtnetlink_rcv_msg+0x791/0xcf0 net/core/rtnetlink.c:6919 netlink_rcv_skb+0x206/0x480 net/netlink/af_netlink.c:2534 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline] netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1339 netlink_sendmsg+0x8de/0xcb0 net/netlink/af_netlink.c:1883 sock_sendmsg_nosec net/socket.c:709 [inline] Fixes: 1dd2af7963e9 ("ipv4: fib: Convert RTM_NEWROUTE and RTM_DELROUTE to per-netns RTNL.") Reported-by: syzbot+3f18ef0f7df107a3f6a0@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/67c6f87a.050a0220.38b91b.0147.GAE@google.com/T/#u Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250304125918.2763514-1-edumazet@google.com Signed-off-by: Jakub Kicinski

ipv4: fib: Convert RTM_NEWROUTE and RTM_DELROUTE to per-netns RTNL.

2025-03-03T23:04:12+00:00

We converted fib_info hash tables to per-netns one and now ready to convert RTM_NEWROUTE and RTM_DELROUTE to per-netns RTNL. Let's hold rtnl_net_lock() in inet_rtm_newroute() and inet_rtm_delroute(). Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Reviewed-by: David Ahern Link: https://patch.msgid.link/20250228042328.96624-13-kuniyu@amazon.com Signed-off-by: Jakub Kicinski

ipv4: fib: Move fib_valid_key_len() to rtm_to_fib_config().

2025-03-03T23:04:11+00:00

fib_valid_key_len() is called in the beginning of fib_table_insert() or fib_table_delete() to check if the prefix length is valid. fib_table_insert() and fib_table_delete() are called from 3 paths - ip_rt_ioctl() - inet_rtm_newroute() / inet_rtm_delroute() - fib_magic() In the first ioctl() path, rtentry_to_fib_config() checks the prefix length with bad_mask(). Also, fib_magic() always passes the correct prefix: 32 or ifa->ifa_prefixlen, which is already validated. Let's move fib_valid_key_len() to the rtnetlink path, rtm_to_fib_config(). While at it, 2 direct returns in rtm_to_fib_config() are changed to goto to match other places in the same function Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Reviewed-by: David Ahern Link: https://patch.msgid.link/20250228042328.96624-12-kuniyu@amazon.com Signed-off-by: Jakub Kicinski

ipv4: fib: Hold rtnl_net_lock() in ip_rt_ioctl().

2025-03-03T23:04:11+00:00

ioctl(SIOCADDRT/SIOCDELRT) calls ip_rt_ioctl() to add/remove a route in the netns of the specified socket. Let's hold rtnl_net_lock() there. Note that rtentry_to_fib_config() can be called without rtnl_net_lock() if we convert rtentry.dev handling to RCU later. Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Reviewed-by: David Ahern Link: https://patch.msgid.link/20250228042328.96624-11-kuniyu@amazon.com Signed-off-by: Jakub Kicinski

ipv4: fib: Hold rtnl_net_lock() for ip_fib_net_exit().

2025-03-03T23:04:11+00:00

ip_fib_net_exit() requires RTNL and is called from fib_net_init() and fib_net_exit_batch(). Let's hold rtnl_net_lock() before ip_fib_net_exit(). Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Reviewed-by: David Ahern Link: https://patch.msgid.link/20250228042328.96624-10-kuniyu@amazon.com Signed-off-by: Jakub Kicinski

ipv4: fib: Allocate fib_info_hash[] during netns initialisation.

2025-03-03T23:04:09+00:00

We will allocate fib_info_hash[] and fib_info_laddrhash[] for each netns. Currently, fib_info_hash[] is allocated when the first route is added. Let's move the first allocation to a new __net_init function. Note that we must call fib4_semantics_exit() in fib_net_exit_batch() because ->exit() is called earlier than ->exit_batch(). Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Reviewed-by: David Ahern Link: https://patch.msgid.link/20250228042328.96624-4-kuniyu@amazon.com Signed-off-by: Jakub Kicinski