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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?uJ21Mx7EBUtncsaCgV2k/hGCIznpI0JjnDdVQcXE5gwF/BQVPXHGzc6a/adt?= =?us-ascii?Q?w+hgGhCkMu7vLDRE48e71vm5lPKNy6EkPbUT5jOCyPTfL6Jj/UEqMMY8OdZN?= =?us-ascii?Q?LFDthx666WcYvjYFkZ36bEwfQLyA3fBC4gj5cXIFU+MlbtJDui7hd5Ai8Dxq?= =?us-ascii?Q?eYZsFuMMRLXPZCKEvPt71EstADty3FF3U4hzkcyT2vyucRlzEz1HEZtF4+BG?= =?us-ascii?Q?iVVk0M0Phu2e8xiTAAQy6qXek3PE7ZIgBly4iFJnoVFTvxoNigJQi8cP9nKA?= =?us-ascii?Q?wluJGPXOk9r4sjd8yNQzUh4I+wgrSPpaIZlzaV0ee7CHKplrmcgyp7DTJjXJ?= =?us-ascii?Q?xW9s6FKvuKpbZDbEVkin3KMwzGYCSue4Rqc7LVqOSRMyhUSvIiLORyDJn9gf?= =?us-ascii?Q?e4eNqKGUgt95t82cHrdKgBNHV8TysxMLeJxIWC4IWOKUE4tJHu6vEWJcP/0S?= =?us-ascii?Q?jWdLOhfAXuBHRElQ0yzjg26zeKRm5Wf7PQOdCl+sTKALUeMLefDHPSJ7RsaN?= =?us-ascii?Q?veewdsByffd1t2RlbNqeFnzSpzE6BacIA1ABry1r0zithgi08p0jnKfuE/Uo?= =?us-ascii?Q?6mjAmyT3a+IUQkfzOJtFqqRY8oAy77knu91VItnYc0nlFUR4C+whc7iLVI88?= =?us-ascii?Q?UzCekZI5BA9WbnF2rZ9d9lIeMG6eCYKLBplczTKbD9T2UT+KUaPQCPWJNDAA?= =?us-ascii?Q?w2/eGSbSK1izcNMpqNXUDEWOd4YpjM/M/fGoD2K3aJCm21bUy0msgtNugyi6?= =?us-ascii?Q?+7Dhjtm1XpoYiO2oe6Z7U2Re8byrTkQnLEuSx1H5DL+am0iVXAWx3LF+XWuc?= =?us-ascii?Q?aPyNf3pgQsZY2LeRzUSfc3wi+WT9UcqUVpQ7QQW67gFZ/dc6P+IdRoGVJDUX?= =?us-ascii?Q?4KLs1viWdvc8pu8i8aYzUVQ33lB2PzFJhUC5XIYmMU5K+OxGlaW1LjCjBMC7?= =?us-ascii?Q?6zZSnfrO2WQuXnM3BZl+1k2o3cw8nmLoDYu8PMO24B/vDvAFOKIGzQNdFMby?= =?us-ascii?Q?vhPbjsdDRzdypITVDvpS6/0ruM+lQhO1yXGOqSuqHoa+i/CplC1lLoZTtWXx?= =?us-ascii?Q?qrAZ2jk8SgZX9g205nLq+gk/c5SnqJ03OCW31lTBHYoXnCDdjkGPlLG1os7y?= =?us-ascii?Q?U0UN8KHy7mbqkztwIDW9JIbkdoNzm/VAXer51GRWXc69bbTw0UnHoeVybDbw?= =?us-ascii?Q?ZqNSuWEBqGSJJ9sVwW10Q5Fg0QMLgXbEjbMfygBQp81wOFfdxfA5L4YipnUd?= =?us-ascii?Q?m3JpW0cJGs3J/5WIEKO04PH8yAv/Yox4r8dayLu4S5Czp2s+7KLDCu2u5puO?= =?us-ascii?Q?ubEudo7hnqzEN3RrKuqpZ6AXhD1K3Jwt5jG2KASPQTLpUQlI1SD8d5yDfGZe?= =?us-ascii?Q?zr+GadLOwPkrei4d17FAU5K72Rn4bfbmJ32yT54pemguAQnbKDRGwCSCt0qD?= =?us-ascii?Q?yZv/WCZ0vHSm1xrMng6tqBtb1JMktvCgozIdag8RQaxJK7MXQjZjy1XwRWN1?= =?us-ascii?Q?zVlfeLtlaw2dlQbY+5pJHRK6UJtFKYTWEtw9FpQvuC9/1bmxjXUyWCh6agg/?= =?us-ascii?Q?sty6DM55mhLoATZQiOI85W6By0GTJkRibKc2e1TBwb5BgQY2NNPbMoUoGOji?= =?us-ascii?Q?3wEEntfU5W8/mqMSbArw9icnPNGZmLRHK++9l4l/il5CAxaemeFFBscYy5kK?= =?us-ascii?Q?J3wVGTtf7qlzcMm0MzTLk3eUgKLaKnc+qfsTO7Cf0kg8JjO9?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 3f8ea74d-cc2f-4b0c-7798-08df198e46fd X-MS-Exchange-CrossTenant-AuthSource: SN7PR12MB7954.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 Sep 2026 16:18:17.8697 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: XCICe0Lj5i9uCzwie5cEcFxICrrUbj2DZqTJOePgIrF+KGzdfmUMCYdZSm23TdZ8ZrLuW2WYxNAZAKDM+HaEsw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: LVUPR12MB999135 The kernel identifies a network namespace by a 64-bit cookie that is assigned when the namespace is created and never changes. The cookie is reported by a growing number of trace events such as the TCP-MD5 and TCP-AO events and the net device events (e.g., net:net_dev_xmit). This allows filtering events that occur in a specific network namespace, for example: # perf record -a -e net:net_dev_xmit --filter 'net_cookie == 12' It is also available to tracing BPF programs that can access 'net_cookie' in 'struct net'. However, no utility currently reports the cookie of a given network namespace, so mapping a cookie in a trace to a namespace requires a custom program that calls getsockopt(SO_NETNS_COOKIE) from within the namespace. Since Linux 6.18, the cookie is also the generic namespace ID and can be retrieved via the NS_GET_ID ioctl on a network namespace file descriptor. Unlike SO_NETNS_COOKIE, this does not require entering the namespace, so the cookie of any namespace whose file can be opened can be retrieved without privileges. A kernel selftest [1] ensures that both interfaces report the same value for a given network namespace. This patchset extends ip-netns to display the network namespace cookie. Patch #1 imports the nsfs.h header that defines the NS_GET_ID ioctl. Patch #2 reports the cookie in "ip netns list". It is always reported in JSON mode and only reported with "-d" in plain text mode to avoid breaking scripts that rely on the current output format. Patch #3 adds "ip netns cookie [ NETNSNAME | PID ]" to report the cookie of a single network namespace, including namespaces that are not bind mounted under /var/run/netns, such as those created by container runtimes. [1] nsid_netns_basic in tools/testing/selftests/namespaces/nsid_test.c Ido Schimmel (3): uapi: import nsfs.h from last sync point ip: netns: report the network namespace cookie ip: netns: add "ip netns cookie" command include/uapi/linux/nsfs.h | 122 ++++++++++++++++++++++++++++++++++++++ ip/ipnetns.c | 71 ++++++++++++++++++++++ man/man8/ip-netns.8.in | 30 +++++++++- 3 files changed, 222 insertions(+), 1 deletion(-) create mode 100644 include/uapi/linux/nsfs.h -- 2.55.0