kernel/linux.git/net/core/rtnetlink.c, branch v5.15.219

rtnetlink: add RTNL_FLAG_DUMP_UNLOCKED flag

2026-07-24T13:51:42+00:00

[ Upstream commit 386520e0ecc01004d3a29c70c5a77d4bbf8a8420 ] Similarly to RTNL_FLAG_DOIT_UNLOCKED, this new flag allows dump operations registered via rtnl_register() or rtnl_register_module() to opt-out from RTNL protection. Signed-off-by: Eric Dumazet Reviewed-by: Donald Hunter Signed-off-by: David S. Miller Stable-dep-of: 9facb861dc6b ("ipv6: fib6: fix NULL deref in fib6_walk_continue() on multi-batch dump") Signed-off-by: Sasha Levin

net: ip_gre: require CAP_NET_ADMIN in the device netns for changelink

2026-07-24T13:51:16+00:00

[ Upstream commit 8165f7ff57d9667d2bb477ef6af83ede7fed4ad7 ] A tunnel changelink() operates on at most two netns, dev_net(dev) and the tunnel link netns t->net. They differ once the device is created in or moved to a netns other than the one the request runs in. The rtnl changelink path checks CAP_NET_ADMIN only against dev_net(dev), so a caller privileged there but not in t->net can rewrite a tunnel that lives in t->net. Add rtnl_dev_link_net_capable() next to rtnl_get_net_ns_capable() in net/core/rtnetlink.c. It requires CAP_NET_ADMIN in the link netns and is skipped when the link netns is dev_net(dev), where the rtnl path already checked it. The other patches in this series use the same helper. Gate ipgre_changelink() and erspan_changelink() with it, at the top of the op before any attribute is parsed, because the parsers update live tunnel fields first. ipgre_netlink_parms() sets t->collect_md before ip_tunnel_changelink() runs. Commit 8b484efd5cb4 ("ip6: vti: Use ip6_tnl.net in vti6_siocdevprivate().") added the same check on the ioctl path. This adds it on RTM_NEWLINK. Reported-by: Xiao Liang Closes: https://lore.kernel.org/netdev/CABAhCOSzP1vaThGV35_VnsRCb=87_CPjPVsTHbq905k8A+BuUg@mail.gmail.com/ Fixes: b57708add314 ("gre: add x-netns support") Cc: stable@vger.kernel.org Signed-off-by: Maoyi Xie Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260612085941.3158249-2-maoyixie.tju@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

net: rtnetlink: zero ifla_vf_broadcast to avoid stack infoleak in rtnl_fill_vfinfo

2026-06-01T15:35:21+00:00

commit 4b9e327991815e128ad3af75c3a04630a63ce3e0 upstream. rtnl_fill_vfinfo() declares struct ifla_vf_broadcast on the stack without initialisation: struct ifla_vf_broadcast vf_broadcast; The struct contains a single fixed 32-byte field: /* include/uapi/linux/if_link.h */ struct ifla_vf_broadcast { __u8 broadcast[32]; }; The function then copies dev->broadcast into it using dev->addr_len as the length: memcpy(vf_broadcast.broadcast, dev->broadcast, dev->addr_len); On Ethernet devices (the overwhelming majority of SR-IOV NICs) dev->addr_len is 6, so only the first 6 bytes of broadcast[] are written. The remaining 26 bytes retain whatever was previously on the kernel stack. The full struct is then handed to userspace via: nla_put(skb, IFLA_VF_BROADCAST, sizeof(vf_broadcast), &vf_broadcast) leaking up to 26 bytes of uninitialised kernel stack per VF per RTM_GETLINK request, repeatable. The other vf_* structs in the same function are explicitly zeroed for exactly this reason - see the memset() calls for ivi, vf_vlan_info, node_guid and port_guid a few lines above. vf_broadcast was simply missed when it was added. Reachability: any unprivileged local process can open AF_NETLINK / NETLINK_ROUTE without capabilities and send RTM_GETLINK with an IFLA_EXT_MASK attribute carrying RTEXT_FILTER_VF. The kernel walks each VF and emits IFLA_VF_BROADCAST, leaking 26 bytes of stack per VF per request. Stack residue at this call site can include return addresses and transient sensitive data; KASAN with stack instrumentation, or KMSAN, will flag the nla_put() when reproduced. Zero the on-stack struct before the partial memcpy, matching the existing pattern used for the other vf_* structs in the same function. Fixes: 75345f888f70 ("ipoib: show VF broadcast address") Cc: stable@vger.kernel.org Signed-off-by: Kai Zen Link: https://patch.msgid.link/3c506e8f936e52b57620269b55c348af05d413a2.1777557228.git.kai.aizen.dev@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

rtnetlink: count IFLA_INFO_SLAVE_KIND in if_nlmsg_size

2026-04-18T08:33:24+00:00

[ Upstream commit ee00a12593ffb69db4dd1a1c00ecb0253376874a ] rtnl_link_get_slave_info_data_size counts IFLA_INFO_SLAVE_DATA, but rtnl_link_slave_info_fill adds both IFLA_INFO_SLAVE_DATA and IFLA_INFO_SLAVE_KIND. Fixes: ba7d49b1f0f8 ("rtnetlink: provide api for getting and setting slave info") Reviewed-by: Jiri Pirko Signed-off-by: Sabrina Dubroca Link: https://patch.msgid.link/049843b532e23cde7ddba263c0bbe35ba6f0d26d.1773919462.git.sd@queasysnail.net Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: rtnetlink: fix module reference count leak issue in rtnetlink_rcv_msg

2025-10-29T13:03:16+00:00

commit 5b22f62724a0a09e00d301abf5b57b0c12be8a16 upstream. When bulk delete command is received in the rtnetlink_rcv_msg function, if bulk delete is not supported, module_put is not called to release the reference counting. As a result, module reference count is leaked. Fixes: a6cec0bcd342 ("net: rtnetlink: add bulk delete support flag") Signed-off-by: Zhengchao Shao Acked-by: Nikolay Aleksandrov Link: https://lore.kernel.org/r/20220815024629.240367-1-shaozhengchao@huawei.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

rtnetlink: Allow deleting FDB entries in user namespace

2025-10-29T13:03:11+00:00

[ Upstream commit bf29555f5bdc017bac22ca66fcb6c9f46ec8788f ] Creating FDB entries is possible from a non-initial user namespace when having CAP_NET_ADMIN, yet, when deleting FDB entries, processes receive an EPERM because the capability is always checked against the initial user namespace. This restricts the FDB management from unprivileged containers. Drop the netlink_capable check in rtnl_fdb_del as it was originally dropped in c5c351088ae7 and reintroduced in 1690be63a27b without intention. This patch was tested using a container on GyroidOS, where it was possible to delete FDB entries from an unprivileged user namespace and private network namespace. Fixes: 1690be63a27b ("bridge: Add vlan support to static neighbors") Reviewed-by: Michael Weiß Tested-by: Harshal Gohel Signed-off-by: Johannes Wiesböck Reviewed-by: Ido Schimmel Reviewed-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20251015201548.319871-1-johannes.wiesboeck@aisec.fraunhofer.de Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: rtnetlink: add NLM_F_BULK support to rtnl_fdb_del

2025-10-29T13:03:11+00:00

[ Upstream commit 9e83425993f38bb89e0ea07849ba0039a748e85b ] When NLM_F_BULK is specified in a fdb del message we need to handle it differently. First since this is a new call we can strictly validate the passed attributes, at first only ifindex and vlan are allowed as these will be the initially supported filter attributes, any other attribute is rejected. The mac address is no longer mandatory, but we use it to error out in older kernels because it cannot be specified with bulk request (the attribute is not allowed) and then we have to dispatch the call to ndo_fdb_del_bulk if the device supports it. The del bulk callback can do further validation of the attributes if necessary. Signed-off-by: Nikolay Aleksandrov Signed-off-by: David S. Miller Stable-dep-of: bf29555f5bdc ("rtnetlink: Allow deleting FDB entries in user namespace") Signed-off-by: Sasha Levin

net: rtnetlink: add bulk delete support flag

2025-10-29T13:03:11+00:00

[ Upstream commit a6cec0bcd34264be8887791594be793b3f12719f ] Add a new rtnl flag (RTNL_FLAG_BULK_DEL_SUPPORTED) which is used to verify that the delete operation allows bulk object deletion. Also emit a warning if anyone tries to set it for non-delete kind. Suggested-by: David Ahern Signed-off-by: Nikolay Aleksandrov Signed-off-by: David S. Miller Stable-dep-of: bf29555f5bdc ("rtnetlink: Allow deleting FDB entries in user namespace") Signed-off-by: Sasha Levin

net: rtnetlink: add helper to extract msg type's kind

2025-10-29T13:03:10+00:00

[ Upstream commit 2e9ea3e30f696fd438319c07836422bb0bbb4608 ] Add a helper which extracts the msg type's kind using the kind mask (0x3). Signed-off-by: Nikolay Aleksandrov Signed-off-by: David S. Miller Stable-dep-of: bf29555f5bdc ("rtnetlink: Allow deleting FDB entries in user namespace") Signed-off-by: Sasha Levin

net: fix crash when config small gso_max_size/gso_ipv4_max_size

2025-05-02T05:44:18+00:00

[ Upstream commit 9ab5cf19fb0e4680f95e506d6c544259bf1111c4 ] Config a small gso_max_size/gso_ipv4_max_size will lead to an underflow in sk_dst_gso_max_size(), which may trigger a BUG_ON crash, because sk->sk_gso_max_size would be much bigger than device limits. Call Trace: tcp_write_xmit tso_segs = tcp_init_tso_segs(skb, mss_now); tcp_set_skb_tso_segs tcp_skb_pcount_set // skb->len = 524288, mss_now = 8 // u16 tso_segs = 524288/8 = 65535 -> 0 tso_segs = DIV_ROUND_UP(skb->len, mss_now) BUG_ON(!tso_segs) Add check for the minimum value of gso_max_size and gso_ipv4_max_size. Fixes: 46e6b992c250 ("rtnetlink: allow GSO maximums to be set on device creation") Fixes: 9eefedd58ae1 ("net: add gso_ipv4_max_size and gro_ipv4_max_size per device") Signed-off-by: Wang Liang Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20241023035213.517386-1-wangliang74@huawei.com Signed-off-by: Jakub Kicinski [ Resolve minor conflicts to fix CVE-2024-50258 ] Signed-off-by: Bin Lan Signed-off-by: Sasha Levin [Harshit: Clean cherrypick from 6.1.y commit] Signed-off-by: Harshit Mogalapalli Signed-off-by: Greg Kroah-Hartman