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[bpf-next,v3,2/4] nsfs: add an ioctl to discover the network namespace cookie

Message ID 20210219154330.93615-3-lmb@cloudflare.com (mailing list archive)
State Changes Requested
Delegated to: BPF
Headers show
Series Expose network namespace cookies to user space | expand


Context Check Description
netdev/cover_letter success Link
netdev/fixes_present success Link
netdev/patch_count success Link
netdev/tree_selection success Clearly marked for bpf-next
netdev/subject_prefix success Link
netdev/cc_maintainers warning 7 maintainers not CCed: yhs@fb.com linux-fsdevel@vger.kernel.org viro@zeniv.linux.org.uk john.fastabend@gmail.com kpsingh@kernel.org songliubraving@fb.com kafai@fb.com
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Link
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 3 this patch: 3
netdev/kdoc success Errors and warnings before: 2 this patch: 2
netdev/verify_fixes success Link
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 32 lines checked
netdev/build_allmodconfig_warn success Errors and warnings before: 3 this patch: 3
netdev/header_inline success Link
netdev/stable success Stable not CCed

Commit Message

Lorenz Bauer Feb. 19, 2021, 3:43 p.m. UTC
Network namespaces have a globally unique non-zero identifier aka a
cookie, in line with socket cookies. Add an ioctl to retrieve the
cookie from user space without going via BPF.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
 fs/nsfs.c                 | 7 +++++++
 include/uapi/linux/nsfs.h | 2 ++
 2 files changed, 9 insertions(+)
diff mbox series


diff --git a/fs/nsfs.c b/fs/nsfs.c
index 800c1d0eb0d0..48198a1b1685 100644
--- a/fs/nsfs.c
+++ b/fs/nsfs.c
@@ -11,6 +11,7 @@ 
 #include <linux/user_namespace.h>
 #include <linux/nsfs.h>
 #include <linux/uaccess.h>
+#include <net/net_namespace.h>
 #include "internal.h"
@@ -191,6 +192,7 @@  static long ns_ioctl(struct file *filp, unsigned int ioctl,
 	struct user_namespace *user_ns;
 	struct ns_common *ns = get_proc_ns(file_inode(filp));
 	uid_t __user *argp;
+	struct net *net_ns;
 	uid_t uid;
 	switch (ioctl) {
@@ -209,6 +211,11 @@  static long ns_ioctl(struct file *filp, unsigned int ioctl,
 		argp = (uid_t __user *) arg;
 		uid = from_kuid_munged(current_user_ns(), user_ns->owner);
 		return put_user(uid, argp);
+		if (ns->ops->type != CLONE_NEWNET)
+			return -EINVAL;
+		net_ns = container_of(ns, struct net, ns);
+		return put_user(net_ns->net_cookie, (u64 __user *)arg);
 		return -ENOTTY;
diff --git a/include/uapi/linux/nsfs.h b/include/uapi/linux/nsfs.h
index a0c8552b64ee..86611c2cf908 100644
--- a/include/uapi/linux/nsfs.h
+++ b/include/uapi/linux/nsfs.h
@@ -15,5 +15,7 @@ 
 #define NS_GET_NSTYPE		_IO(NSIO, 0x3)
 /* Get owner UID (in the caller's user namespace) for a user namespace */
 #define NS_GET_OWNER_UID	_IO(NSIO, 0x4)
+/* Returns a unique non-zero identifier for a network namespace */
+#define NS_GET_COOKIE		_IO(NSIO, 0x5)
 #endif /* __LINUX_NSFS_H */