[PATCH bpf 2/4] nsfs: add an ioctl to discover the network namespace cookie
From: Lorenz Bauer <hidden>
Date: 2021-02-10 12:13:37
Also in:
linux-api, linux-fsdevel, lkml, netdev
Subsystem:
filesystems (vfs and infrastructure), networking [general], the rest · Maintainers:
Alexander Viro, Christian Brauner, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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. Cc: linux-api@vger.kernel.org Signed-off-by: Lorenz Bauer <redacted> --- fs/nsfs.c | 9 +++++++++ include/net/net_namespace.h | 11 +++++++++++ include/uapi/linux/nsfs.h | 2 ++ 3 files changed, 22 insertions(+)
diff --git a/fs/nsfs.c b/fs/nsfs.c
index 800c1d0eb0d0..d7865e39c049 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 +192,8 @@ 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; + u64 cookie; uid_t uid; switch (ioctl) {
@@ -209,6 +212,12 @@ 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); + case NS_GET_COOKIE: + if (ns->ops->type != CLONE_NEWNET) + return -EINVAL; + net_ns = container_of(ns, struct net, ns); + cookie = net_gen_cookie(net_ns); + return put_user(cookie, (u64 __user *)arg); default: return -ENOTTY; }
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 29567875f428..bbd22dfa9345 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h@@ -226,6 +226,17 @@ struct net *get_net_ns_by_fd(int fd); u64 __net_gen_cookie(struct net *net); +static inline u64 net_gen_cookie(struct net *net) +{ + u64 cookie; + + preempt_disable(); + cookie = __net_gen_cookie(net); + preempt_enable(); + + return cookie; +} + #ifdef CONFIG_SYSCTL void ipx_register_sysctl(void); void ipx_unregister_sysctl(void);
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 */
--
2.27.0