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Date: Fri, 30 Nov 2018 14:36:57 -1000
From: Joey Pabalinas <joeypabalinas@...il.com>
To: Joe Stringer <joe@...d.net.nz>
Cc: daniel@...earbox.net, ast@...nel.org, netdev@...r.kernel.org,
dsahern@...il.com, nicolas.dichtel@...nd.com,
Joey Pabalinas <joeypabalinas@...il.com>
Subject: Re: [PATCHv3 bpf 1/2] bpf: Support sk lookup in netns with id 0
On Fri, Nov 30, 2018 at 03:32:20PM -0800, Joe Stringer wrote:
> + * the netns associated with the *ctx*. *netns* values beyond the
> + * range of 32-bit integers are reserved for future use.
Would adding a word or two before "*netns*" here be helpful to placate
the english pedants among us (such as myself)? Starting a sentence with
a lowercase word, even if it's a variable name, just never really sits
right with me.
Any *netns* values ...
Doesn't that kind of flow a bit better anyway?
Anyway, now with that unimportant nitpick if off my chest, the rest
looks fine to me. Ack with or without any changes to that comment.
Acked-by: Joey Pabalinas <joeypabalinas@...il.com>
On Fri, Nov 30, 2018 at 03:32:20PM -0800, Joe Stringer wrote:
> David Ahern and Nicolas Dichtel report that the handling of the netns id
> 0 is incorrect for the BPF socket lookup helpers: rather than finding
> the netns with id 0, it is resolving to the current netns. This renders
> the netns_id 0 inaccessible.
>
> To fix this, adjust the API for the netns to treat all negative s32
> values as a lookup in the current netns (including u64 values which when
> truncated to s32 become negative), while any values with a positive
> value in the signed 32-bit integer space would result in a lookup for a
> socket in the netns corresponding to that id. As before, if the netns
> with that ID does not exist, no socket will be found. Any netns outside
> of these ranges will fail to find a corresponding socket, as those
> values are reserved for future usage.
>
> Signed-off-by: Joe Stringer <joe@...d.net.nz>
> Acked-by: Nicolas Dichtel <nicolas.dichtel@...nd.com>
> ---
> include/uapi/linux/bpf.h | 35 ++++++++++-------
> net/core/filter.c | 11 +++---
> tools/include/uapi/linux/bpf.h | 39 ++++++++++++-------
> tools/testing/selftests/bpf/bpf_helpers.h | 4 +-
> .../selftests/bpf/test_sk_lookup_kern.c | 18 ++++-----
> 5 files changed, 63 insertions(+), 44 deletions(-)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 852dc17ab47a..ad68b472dad2 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -2170,7 +2170,7 @@ union bpf_attr {
> * Return
> * 0 on success, or a negative error in case of failure.
> *
> - * struct bpf_sock *bpf_sk_lookup_tcp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u32 netns, u64 flags)
> + * struct bpf_sock *bpf_sk_lookup_tcp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
> * Description
> * Look for TCP socket matching *tuple*, optionally in a child
> * network namespace *netns*. The return value must be checked,
> @@ -2187,12 +2187,14 @@ union bpf_attr {
> * **sizeof**\ (*tuple*\ **->ipv6**)
> * Look for an IPv6 socket.
> *
> - * If the *netns* is zero, then the socket lookup table in the
> - * netns associated with the *ctx* will be used. For the TC hooks,
> - * this in the netns of the device in the skb. For socket hooks,
> - * this in the netns of the socket. If *netns* is non-zero, then
> - * it specifies the ID of the netns relative to the netns
> - * associated with the *ctx*.
> + * If the *netns* is a negative signed 32-bit integer, then the
> + * socket lookup table in the netns associated with the *ctx* will
> + * will be used. For the TC hooks, this is the netns of the device
> + * in the skb. For socket hooks, this is the netns of the socket.
> + * If *netns* is any other signed 32-bit value greater than or
> + * equal to zero then it specifies the ID of the netns relative to
> + * the netns associated with the *ctx*. *netns* values beyond the
> + * range of 32-bit integers are reserved for future use.
> *
> * All values for *flags* are reserved for future usage, and must
> * be left at zero.
> @@ -2202,7 +2204,7 @@ union bpf_attr {
> * Return
> * Pointer to *struct bpf_sock*, or NULL in case of failure.
> *
> - * struct bpf_sock *bpf_sk_lookup_udp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u32 netns, u64 flags)
> + * struct bpf_sock *bpf_sk_lookup_udp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
> * Description
> * Look for UDP socket matching *tuple*, optionally in a child
> * network namespace *netns*. The return value must be checked,
> @@ -2219,12 +2221,14 @@ union bpf_attr {
> * **sizeof**\ (*tuple*\ **->ipv6**)
> * Look for an IPv6 socket.
> *
> - * If the *netns* is zero, then the socket lookup table in the
> - * netns associated with the *ctx* will be used. For the TC hooks,
> - * this in the netns of the device in the skb. For socket hooks,
> - * this in the netns of the socket. If *netns* is non-zero, then
> - * it specifies the ID of the netns relative to the netns
> - * associated with the *ctx*.
> + * If the *netns* is a negative signed 32-bit integer, then the
> + * socket lookup table in the netns associated with the *ctx* will
> + * will be used. For the TC hooks, this is the netns of the device
> + * in the skb. For socket hooks, this is the netns of the socket.
> + * If *netns* is any other signed 32-bit value greater than or
> + * equal to zero then it specifies the ID of the netns relative to
> + * the netns associated with the *ctx*. *netns* values beyond the
> + * range of 32-bit integers are reserved for future use.
> *
> * All values for *flags* are reserved for future usage, and must
> * be left at zero.
> @@ -2405,6 +2409,9 @@ enum bpf_func_id {
> /* BPF_FUNC_perf_event_output for sk_buff input context. */
> #define BPF_F_CTXLEN_MASK (0xfffffULL << 32)
>
> +/* Current network namespace */
> +#define BPF_F_CURRENT_NETNS (-1L)
> +
> /* Mode for BPF_FUNC_skb_adjust_room helper. */
> enum bpf_adj_room_mode {
> BPF_ADJ_ROOM_NET,
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 9a1327eb25fa..d00b55929ab8 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -4890,22 +4890,23 @@ bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
> struct net *net;
>
> family = len == sizeof(tuple->ipv4) ? AF_INET : AF_INET6;
> - if (unlikely(family == AF_UNSPEC || netns_id > U32_MAX || flags))
> + if (unlikely(family == AF_UNSPEC || flags ||
> + !((s32)netns_id < 0 || netns_id <= S32_MAX)))
> goto out;
>
> if (skb->dev)
> caller_net = dev_net(skb->dev);
> else
> caller_net = sock_net(skb->sk);
> - if (netns_id) {
> + if ((s32)netns_id < 0) {
> + net = caller_net;
> + sk = sk_lookup(net, tuple, skb, family, proto);
> + } else {
> net = get_net_ns_by_id(caller_net, netns_id);
> if (unlikely(!net))
> goto out;
> sk = sk_lookup(net, tuple, skb, family, proto);
> put_net(net);
> - } else {
> - net = caller_net;
> - sk = sk_lookup(net, tuple, skb, family, proto);
> }
>
> if (sk)
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index 852dc17ab47a..de2072ef475b 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -2170,7 +2170,7 @@ union bpf_attr {
> * Return
> * 0 on success, or a negative error in case of failure.
> *
> - * struct bpf_sock *bpf_sk_lookup_tcp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u32 netns, u64 flags)
> + * struct bpf_sock *bpf_sk_lookup_tcp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
> * Description
> * Look for TCP socket matching *tuple*, optionally in a child
> * network namespace *netns*. The return value must be checked,
> @@ -2187,12 +2187,14 @@ union bpf_attr {
> * **sizeof**\ (*tuple*\ **->ipv6**)
> * Look for an IPv6 socket.
> *
> - * If the *netns* is zero, then the socket lookup table in the
> - * netns associated with the *ctx* will be used. For the TC hooks,
> - * this in the netns of the device in the skb. For socket hooks,
> - * this in the netns of the socket. If *netns* is non-zero, then
> - * it specifies the ID of the netns relative to the netns
> - * associated with the *ctx*.
> + * If the *netns* is a negative signed 32-bit integer, then the
> + * socket lookup table in the netns associated with the *ctx* will
> + * will be used. For the TC hooks, this is the netns of the device
> + * in the skb. For socket hooks, this is the netns of the socket.
> + * If *netns* is any other signed 32-bit value greater than or
> + * equal to zero then it specifies the ID of the netns relative to
> + * the netns associated with the *ctx*. *netns* values beyond the
> + * range of 32-bit integers are reserved for future use.
> *
> * All values for *flags* are reserved for future usage, and must
> * be left at zero.
> @@ -2201,8 +2203,10 @@ union bpf_attr {
> * **CONFIG_NET** configuration option.
> * Return
> * Pointer to *struct bpf_sock*, or NULL in case of failure.
> + * For sockets with reuseport option, *struct bpf_sock*
> + * return is from reuse->socks[] using hash of the packet.
> *
> - * struct bpf_sock *bpf_sk_lookup_udp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u32 netns, u64 flags)
> + * struct bpf_sock *bpf_sk_lookup_udp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
> * Description
> * Look for UDP socket matching *tuple*, optionally in a child
> * network namespace *netns*. The return value must be checked,
> @@ -2219,12 +2223,14 @@ union bpf_attr {
> * **sizeof**\ (*tuple*\ **->ipv6**)
> * Look for an IPv6 socket.
> *
> - * If the *netns* is zero, then the socket lookup table in the
> - * netns associated with the *ctx* will be used. For the TC hooks,
> - * this in the netns of the device in the skb. For socket hooks,
> - * this in the netns of the socket. If *netns* is non-zero, then
> - * it specifies the ID of the netns relative to the netns
> - * associated with the *ctx*.
> + * If the *netns* is a negative signed 32-bit integer, then the
> + * socket lookup table in the netns associated with the *ctx* will
> + * will be used. For the TC hooks, this is the netns of the device
> + * in the skb. For socket hooks, this is the netns of the socket.
> + * If *netns* is any other signed 32-bit value greater than or
> + * equal to zero then it specifies the ID of the netns relative to
> + * the netns associated with the *ctx*. *netns* values beyond the
> + * range of 32-bit integers are reserved for future use.
> *
> * All values for *flags* are reserved for future usage, and must
> * be left at zero.
> @@ -2233,6 +2239,8 @@ union bpf_attr {
> * **CONFIG_NET** configuration option.
> * Return
> * Pointer to *struct bpf_sock*, or NULL in case of failure.
> + * For sockets with reuseport option, *struct bpf_sock*
> + * return is from reuse->socks[] using hash of the packet.
> *
> * int bpf_sk_release(struct bpf_sock *sk)
> * Description
> @@ -2405,6 +2413,9 @@ enum bpf_func_id {
> /* BPF_FUNC_perf_event_output for sk_buff input context. */
> #define BPF_F_CTXLEN_MASK (0xfffffULL << 32)
>
> +/* Current network namespace */
> +#define BPF_F_CURRENT_NETNS (-1L)
> +
> /* Mode for BPF_FUNC_skb_adjust_room helper. */
> enum bpf_adj_room_mode {
> BPF_ADJ_ROOM_NET,
> diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
> index 686e57ce40f4..efb6c13ab0de 100644
> --- a/tools/testing/selftests/bpf/bpf_helpers.h
> +++ b/tools/testing/selftests/bpf/bpf_helpers.h
> @@ -154,12 +154,12 @@ static unsigned long long (*bpf_skb_ancestor_cgroup_id)(void *ctx, int level) =
> (void *) BPF_FUNC_skb_ancestor_cgroup_id;
> static struct bpf_sock *(*bpf_sk_lookup_tcp)(void *ctx,
> struct bpf_sock_tuple *tuple,
> - int size, unsigned int netns_id,
> + int size, unsigned long long netns_id,
> unsigned long long flags) =
> (void *) BPF_FUNC_sk_lookup_tcp;
> static struct bpf_sock *(*bpf_sk_lookup_udp)(void *ctx,
> struct bpf_sock_tuple *tuple,
> - int size, unsigned int netns_id,
> + int size, unsigned long long netns_id,
> unsigned long long flags) =
> (void *) BPF_FUNC_sk_lookup_udp;
> static int (*bpf_sk_release)(struct bpf_sock *sk) =
> diff --git a/tools/testing/selftests/bpf/test_sk_lookup_kern.c b/tools/testing/selftests/bpf/test_sk_lookup_kern.c
> index b745bdc08c2b..e21cd736c196 100644
> --- a/tools/testing/selftests/bpf/test_sk_lookup_kern.c
> +++ b/tools/testing/selftests/bpf/test_sk_lookup_kern.c
> @@ -72,7 +72,7 @@ int bpf_sk_lookup_test0(struct __sk_buff *skb)
> return TC_ACT_SHOT;
>
> tuple_len = ipv4 ? sizeof(tuple->ipv4) : sizeof(tuple->ipv6);
> - sk = bpf_sk_lookup_tcp(skb, tuple, tuple_len, 0, 0);
> + sk = bpf_sk_lookup_tcp(skb, tuple, tuple_len, BPF_F_CURRENT_NETNS, 0);
> if (sk)
> bpf_sk_release(sk);
> return sk ? TC_ACT_OK : TC_ACT_UNSPEC;
> @@ -84,7 +84,7 @@ int bpf_sk_lookup_test1(struct __sk_buff *skb)
> struct bpf_sock_tuple tuple = {};
> struct bpf_sock *sk;
>
> - sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), 0, 0);
> + sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
> if (sk)
> bpf_sk_release(sk);
> return 0;
> @@ -97,7 +97,7 @@ int bpf_sk_lookup_uaf(struct __sk_buff *skb)
> struct bpf_sock *sk;
> __u32 family = 0;
>
> - sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), 0, 0);
> + sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
> if (sk) {
> bpf_sk_release(sk);
> family = sk->family;
> @@ -112,7 +112,7 @@ int bpf_sk_lookup_modptr(struct __sk_buff *skb)
> struct bpf_sock *sk;
> __u32 family;
>
> - sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), 0, 0);
> + sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
> if (sk) {
> sk += 1;
> bpf_sk_release(sk);
> @@ -127,7 +127,7 @@ int bpf_sk_lookup_modptr_or_null(struct __sk_buff *skb)
> struct bpf_sock *sk;
> __u32 family;
>
> - sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), 0, 0);
> + sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
> sk += 1;
> if (sk)
> bpf_sk_release(sk);
> @@ -139,7 +139,7 @@ int bpf_sk_lookup_test2(struct __sk_buff *skb)
> {
> struct bpf_sock_tuple tuple = {};
>
> - bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), 0, 0);
> + bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
> return 0;
> }
>
> @@ -149,7 +149,7 @@ int bpf_sk_lookup_test3(struct __sk_buff *skb)
> struct bpf_sock_tuple tuple = {};
> struct bpf_sock *sk;
>
> - sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), 0, 0);
> + sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
> bpf_sk_release(sk);
> bpf_sk_release(sk);
> return 0;
> @@ -161,7 +161,7 @@ int bpf_sk_lookup_test4(struct __sk_buff *skb)
> struct bpf_sock_tuple tuple = {};
> struct bpf_sock *sk;
>
> - sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), 0, 0);
> + sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
> bpf_sk_release(sk);
> return 0;
> }
> @@ -169,7 +169,7 @@ int bpf_sk_lookup_test4(struct __sk_buff *skb)
> void lookup_no_release(struct __sk_buff *skb)
> {
> struct bpf_sock_tuple tuple = {};
> - bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), 0, 0);
> + bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
> }
>
> SEC("fail_no_release_subcall")
> --
> 2.19.1
>
--
Cheers,
Joey Pabalinas
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