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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , netdev@vger.kernel.org Subject: [PATCH v2 1/4] net: add helper for device lookup by destination address Date: Mon, 27 Jul 2026 20:46:44 +0530 Message-ID: <20260727151652.3660476-2-nilay@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260727151652.3660476-1-nilay@linux.ibm.com> References: <20260727151652.3660476-1-nilay@linux.ibm.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzI3MDE0NCBTYWx0ZWRfX5zYZv3bi0Ijb aO3pWPuFsixWKP28DeNMcO2OFrR/6paK+xpNMUOJzMRpYW+dtyScFvb9aA9nL77imRIKQOS4yuL mxbrVEVQ9gegWvi1WjK4e8u7+QAsYI0= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzI3MDE0NCBTYWx0ZWRfX34F6RiZWIWBV X53RJDBVDQajSYVteHgQuTzvle0XBcdwm1FfsubXyYGImwZNpz/d5i5pD5GhR5TmfHhUXMEoqgI hd60DLhhO3fdDu9bRl235NVEVdvCNoSKw4Y7orn33cEneKX28e7j6uhjQOKBfJG+L5LC2fWSOAB 9OSsesqJtuC07MI8cJUWdWiilWAvDxMAVAPN/qguqu4893RopbmY9KE1iBjqH+bozyGXt7DkjrZ dABkPladecpdP3FiXNTzJvOxdx2dg8d+gTAX+FxHNPEoSPc9fRmpqQMH2DnyishSWqTQm6COC/P 17nz98CmWYMbTayx+KU1rjMlc5ilVFPwmWRLHikSgMQJOE6aE8NACqa4vEgfNKFay+DulyER08w H6ZvDq8in+a96L7axrFoK6O9n/6RO2CFJRfAgTg+0PNxy+dZyxX3wNocpv2vWhnFOmXRJ4tBwxc 4XV8vn6SxRjCx5Rfd5A== X-Authority-Analysis: v=2.4 cv=b5WCJNGx c=1 sm=1 tr=0 ts=6a677686 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=J1Y8HTJGAAAA:8 a=1XWaLZrsAAAA:8 a=VwQbUJbxAAAA:8 a=20KFwNOVAAAA:8 a=VnNF1IyMAAAA:8 a=1_uPL4OANAtoORD1zUkA:9 a=y1Q9-5lHfBjTkpIzbSAN:22 X-Proofpoint-GUID: S-Rik2n8-L9oDcmUSwM9CEgUlnpOU-mO X-Proofpoint-ORIG-GUID: tLxCO4ILLM8EvPpaiA4FLZsGBh-RhEY0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-27_04,2026-07-24_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 spamscore=0 adultscore=0 malwarescore=0 impostorscore=0 bulkscore=0 phishscore=0 suspectscore=0 clxscore=1011 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607270144 Add netdev_get_by_addr(), a helper that looks up the routing table to retrieve the network device associated with a destination address. The helper also supports netdev reference tracking. Cc: "David S. Miller" Cc: Eric Dumazet Cc: Jakub Kicinski Cc: Paolo Abeni Cc: Simon Horman Cc: netdev@vger.kernel.org Signed-off-by: Nilay Shroff --- include/linux/netdevice.h | 5 +++ net/core/dev.c | 84 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 89 insertions(+) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 9981d637f8b5..f43c3aa8486c 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -3487,6 +3487,11 @@ struct net_device *netdev_get_by_index(struct net *net, int ifindex, struct net_device *netdev_get_by_index_lock(struct net *net, int ifindex); struct net_device *netdev_get_by_name(struct net *net, const char *name, netdevice_tracker *tracker, gfp_t gfp); +struct net_device *netdev_get_by_addr(struct net *net, + struct sockaddr_storage *src, + struct sockaddr_storage *dest, + netdevice_tracker *tracker, + gfp_t gfp); struct net_device *netdev_get_by_flags_rcu(struct net *net, netdevice_tracker *tracker, unsigned short flags, unsigned short mask); struct net_device *dev_get_by_index_rcu(struct net *net, int ifindex); diff --git a/net/core/dev.c b/net/core/dev.c index 5933c5dab09e..fd8afcd26de4 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -163,6 +163,8 @@ #include #include #include +#include +#include #include "dev.h" #include "devmem.h" @@ -944,6 +946,88 @@ struct net_device *netdev_get_by_name(struct net *net, const char *name, } EXPORT_SYMBOL(netdev_get_by_name); +/** + * netdev_get_by_addr() - find an egress device by destination address + * @net: the applicable net namespace + * @src: optional source address + * @dest: destination address + * @tracker: tracking onject for the acquired reference + * @gfp: allocation flag for the tracker + * + * Find an interface by looking up route table entry based on dest address + * and an optional src address. The returned handle has the usage count + * incremented and the caller must use netdev_put() to release it when it + * is no longer needed. %NULL is returned if dest is not specified, or src + * and dest belong to different address families, or no matching device is + * found. + */ +struct net_device *netdev_get_by_addr(struct net *net, + struct sockaddr_storage *src, + struct sockaddr_storage *dest, + netdevice_tracker *tracker, + gfp_t gfp) +{ + struct net_device *dev = NULL; + + if (!dest) + return NULL; + + if (src && src->ss_family != dest->ss_family) + return NULL; + + if (dest->ss_family == AF_INET) { + struct rtable *rt; + struct flowi4 fl4 = {}; + + fl4.daddr = ((struct sockaddr_in *)dest)->sin_addr.s_addr; + if (src) + fl4.saddr = ((struct sockaddr_in *)src)->sin_addr.s_addr; + + rt = ip_route_output_key(net, &fl4); + if (IS_ERR(rt)) + return NULL; + + dev = dst_dev(&rt->dst); + /* + * Get reference to netdev as ip_rt_put() will release netdev + * reference. + */ + if (dev) + netdev_hold(dev, tracker, gfp); + + ip_rt_put(rt); + +#if IS_ENABLED(CONFIG_IPV6) + } else if (dest->ss_family == AF_INET6) { + struct dst_entry *dst; + struct flowi6 fl6 = {}; + + fl6.daddr = ((struct sockaddr_in6 *)dest)->sin6_addr; + if (src) + fl6.saddr = ((struct sockaddr_in6 *)src)->sin6_addr; + + dst = ip6_route_output(net, NULL, &fl6); + if (dst->error) { + dst_release(dst); + return NULL; + } + + dev = dst_dev(dst); + /* + * Get reference to netdev as dst_release() will + * release the netdev reference. + */ + if (dev) + netdev_hold(dev, tracker, gfp); + + dst_release(dst); +#endif + } + + return dev; +} +EXPORT_SYMBOL(netdev_get_by_addr); + /** * __dev_get_by_index - find a device by its ifindex * @net: the applicable net namespace -- 2.53.0