| Message ID | 20210210120425.53438-2-lmb@cloudflare.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | Expose network namespace cookies to user space | expand |
On 2/10/21 1:04 PM, Lorenz Bauer wrote: > We need to distinguish which network namespace a socket belongs to. > BPF has the useful bpf_get_netns_cookie helper for this, but accessing > it from user space isn't possible. Add a read-only socket option that > returns the netns cookie, similar to SO_COOKIE. If network namespaces > are disabled, SO_NETNS_COOKIE returns the cookie of init_net. > > The BPF helpers change slightly: instead of returning 0 when network > namespaces are disabled we return the init_net cookie as for the > socket option. > > Cc: linux-api@vger.kernel.org > Signed-off-by: Lorenz Bauer <lmb@cloudflare.com> > --- ... > > +static inline u64 __sock_gen_netns_cookie(struct sock *sk) > +{ > +#ifdef CONFIG_NET_NS > + return __net_gen_cookie(sk->sk_net.net); > +#else > + return __net_gen_cookie(&init_net); > +#endif > +} > + > +static inline u64 sock_gen_netns_cookie(struct sock *sk) > +{ > + u64 cookie; > + > + preempt_disable(); > + cookie = __sock_gen_netns_cookie(sk); > + preempt_enable(); > + > + return cookie; > +} > + > I suggest we make net->net_cookie a mere u64 initialized in setup_net(), instead of having to preempt_disable() around reading it. (Here and in your patch 2/4) Your patches would be much simpler. Cleanup patch : https://patchwork.kernel.org/project/netdevbpf/patch/20210210144144.24284-1-eric.dumazet@gmail.com/
diff --git a/arch/alpha/include/uapi/asm/socket.h b/arch/alpha/include/uapi/asm/socket.h index 57420356ce4c..6b3daba60987 100644 --- a/arch/alpha/include/uapi/asm/socket.h +++ b/arch/alpha/include/uapi/asm/socket.h @@ -127,6 +127,8 @@ #define SO_PREFER_BUSY_POLL 69 #define SO_BUSY_POLL_BUDGET 70 +#define SO_NETNS_COOKIE 71 + #if !defined(__KERNEL__) #if __BITS_PER_LONG == 64 diff --git a/arch/mips/include/uapi/asm/socket.h b/arch/mips/include/uapi/asm/socket.h index 2d949969313b..cdf404a831b2 100644 --- a/arch/mips/include/uapi/asm/socket.h +++ b/arch/mips/include/uapi/asm/socket.h @@ -138,6 +138,8 @@ #define SO_PREFER_BUSY_POLL 69 #define SO_BUSY_POLL_BUDGET 70 +#define SO_NETNS_COOKIE 71 + #if !defined(__KERNEL__) #if __BITS_PER_LONG == 64 diff --git a/arch/parisc/include/uapi/asm/socket.h b/arch/parisc/include/uapi/asm/socket.h index f60904329bbc..5b5351cdcb33 100644 --- a/arch/parisc/include/uapi/asm/socket.h +++ b/arch/parisc/include/uapi/asm/socket.h @@ -119,6 +119,8 @@ #define SO_PREFER_BUSY_POLL 0x4043 #define SO_BUSY_POLL_BUDGET 0x4044 +#define SO_NETNS_COOKIE 0x4045 + #if !defined(__KERNEL__) #if __BITS_PER_LONG == 64 diff --git a/arch/sparc/include/uapi/asm/socket.h b/arch/sparc/include/uapi/asm/socket.h index 848a22fbac20..ff79db753dce 100644 --- a/arch/sparc/include/uapi/asm/socket.h +++ b/arch/sparc/include/uapi/asm/socket.h @@ -120,6 +120,8 @@ #define SO_PREFER_BUSY_POLL 0x0048 #define SO_BUSY_POLL_BUDGET 0x0049 +#define SO_NETNS_COOKIE 0x004a + #if !defined(__KERNEL__) diff --git a/include/linux/sock_diag.h b/include/linux/sock_diag.h index 0b9ecd8cf979..6e88436097b1 100644 --- a/include/linux/sock_diag.h +++ b/include/linux/sock_diag.h @@ -38,6 +38,26 @@ static inline u64 sock_gen_cookie(struct sock *sk) return cookie; } +static inline u64 __sock_gen_netns_cookie(struct sock *sk) +{ +#ifdef CONFIG_NET_NS + return __net_gen_cookie(sk->sk_net.net); +#else + return __net_gen_cookie(&init_net); +#endif +} + +static inline u64 sock_gen_netns_cookie(struct sock *sk) +{ + u64 cookie; + + preempt_disable(); + cookie = __sock_gen_netns_cookie(sk); + preempt_enable(); + + return cookie; +} + int sock_diag_check_cookie(struct sock *sk, const __u32 *cookie); void sock_diag_save_cookie(struct sock *sk, __u32 *cookie); diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h index 4dcd13d097a9..d588c244ec2f 100644 --- a/include/uapi/asm-generic/socket.h +++ b/include/uapi/asm-generic/socket.h @@ -122,6 +122,8 @@ #define SO_PREFER_BUSY_POLL 69 #define SO_BUSY_POLL_BUDGET 70 +#define SO_NETNS_COOKIE 71 + #if !defined(__KERNEL__) #if __BITS_PER_LONG == 64 || (defined(__x86_64__) && defined(__ILP32__)) diff --git a/net/core/filter.c b/net/core/filter.c index e15d4741719a..51f47b6913f1 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -4645,11 +4645,10 @@ static const struct bpf_func_proto bpf_get_socket_cookie_sock_ops_proto = { static u64 __bpf_get_netns_cookie(struct sock *sk) { -#ifdef CONFIG_NET_NS - return __net_gen_cookie(sk ? sk->sk_net.net : &init_net); -#else - return 0; -#endif + if (sk) + return __sock_gen_netns_cookie(sk); + + return __net_gen_cookie(&init_net); } BPF_CALL_1(bpf_get_netns_cookie_sock, struct sock *, ctx) diff --git a/net/core/sock.c b/net/core/sock.c index bbcd4b97eddd..2db201c210ca 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1606,6 +1606,13 @@ int sock_getsockopt(struct socket *sock, int level, int optname, v.val = sk->sk_bound_dev_if; break; + case SO_NETNS_COOKIE: + lv = sizeof(u64); + if (len < lv) + return -EINVAL; + v.val64 = sock_gen_netns_cookie(sk); + break; + default: /* We implement the SO_SNDLOWAT etc to not be settable * (1003.1g 7).
We need to distinguish which network namespace a socket belongs to. BPF has the useful bpf_get_netns_cookie helper for this, but accessing it from user space isn't possible. Add a read-only socket option that returns the netns cookie, similar to SO_COOKIE. If network namespaces are disabled, SO_NETNS_COOKIE returns the cookie of init_net. The BPF helpers change slightly: instead of returning 0 when network namespaces are disabled we return the init_net cookie as for the socket option. Cc: linux-api@vger.kernel.org Signed-off-by: Lorenz Bauer <lmb@cloudflare.com> --- arch/alpha/include/uapi/asm/socket.h | 2 ++ arch/mips/include/uapi/asm/socket.h | 2 ++ arch/parisc/include/uapi/asm/socket.h | 2 ++ arch/sparc/include/uapi/asm/socket.h | 2 ++ include/linux/sock_diag.h | 20 ++++++++++++++++++++ include/uapi/asm-generic/socket.h | 2 ++ net/core/filter.c | 9 ++++----- net/core/sock.c | 7 +++++++ 8 files changed, 41 insertions(+), 5 deletions(-)