| Message ID | 20190422155552.222910-4-sdf@google.com |
|---|---|
| State | Accepted |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | net: flow_dissector: trigger BPF hook when called from eth_get_headlen | expand |
On Mon, 2019-04-22 at 08:55 -0700, Stanislav Fomichev wrote: > This new argument will be used in the next patches for the > eth_get_headlen use case. eth_get_headlen calls flow dissector > with only data (without skb) so there is currently no way to > pull attached BPF flow dissector program. With this new argument, > we can amend the callers to explicitly pass network namespace > so we can use attached BPF program. > > Signed-off-by: Stanislav Fomichev <sdf@google.com> > --- > include/linux/skbuff.h | 19 +++++++++++-------- > net/core/flow_dissector.c | 27 +++++++++++++++++---------- > net/ethernet/eth.c | 5 +++-- > 3 files changed, 31 insertions(+), 20 deletions(-) > > diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h > index beaedd487be1..ee7d1a85f624 100644 > --- a/include/linux/skbuff.h > +++ b/include/linux/skbuff.h > @@ -1284,7 +1284,8 @@ bool __skb_flow_bpf_dissect(struct bpf_prog > *prog, > const struct sk_buff *skb, > struct flow_dissector *flow_dissector, > struct bpf_flow_keys *flow_keys); > -bool __skb_flow_dissect(const struct sk_buff *skb, > +bool __skb_flow_dissect(const struct net *net, > + const struct sk_buff *skb, > struct flow_dissector *flow_dissector, > void *target_container, > void *data, __be16 proto, int nhoff, int hlen, > @@ -1294,8 +1295,8 @@ static inline bool skb_flow_dissect(const > struct sk_buff *skb, > struct flow_dissector > *flow_dissector, > void *target_container, unsigned > int flags) > { > - return __skb_flow_dissect(skb, flow_dissector, > target_container, > - NULL, 0, 0, 0, flags); > + return __skb_flow_dissect(NULL, skb, flow_dissector, > + target_container, NULL, 0, 0, 0, > flags); > } > > static inline bool skb_flow_dissect_flow_keys(const struct sk_buff > *skb, > @@ -1303,18 +1304,19 @@ static inline bool > skb_flow_dissect_flow_keys(const struct sk_buff *skb, > unsigned int flags) > { > memset(flow, 0, sizeof(*flow)); > - return __skb_flow_dissect(skb, &flow_keys_dissector, flow, > - NULL, 0, 0, 0, flags); > + return __skb_flow_dissect(NULL, skb, &flow_keys_dissector, > + flow, NULL, 0, 0, 0, flags); > } > > static inline bool > -skb_flow_dissect_flow_keys_basic(const struct sk_buff *skb, > +skb_flow_dissect_flow_keys_basic(const struct net *net, > + const struct sk_buff *skb, > struct flow_keys_basic *flow, void > *data, > __be16 proto, int nhoff, int hlen, > unsigned int flags) > { > memset(flow, 0, sizeof(*flow)); > - return __skb_flow_dissect(skb, &flow_keys_basic_dissector, > flow, > + return __skb_flow_dissect(net, skb, &flow_keys_basic_dissector, > flow, > data, proto, nhoff, hlen, flags); > } > > @@ -2494,7 +2496,8 @@ static inline void > skb_probe_transport_header(struct sk_buff *skb) > if (skb_transport_header_was_set(skb)) > return; > > - if (skb_flow_dissect_flow_keys_basic(skb, &keys, NULL, 0, 0, 0, > 0)) > + if (skb_flow_dissect_flow_keys_basic(NULL, skb, &keys, > + NULL, 0, 0, 0, 0)) > skb_set_transport_header(skb, keys.control.thoff); > } > > diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c > index ef6d9443cc75..f32c7e737fc6 100644 > --- a/net/core/flow_dissector.c > +++ b/net/core/flow_dissector.c > @@ -722,6 +722,7 @@ bool bpf_flow_dissect(struct bpf_prog *prog, > struct bpf_flow_dissector *ctx, > > /** > * __skb_flow_dissect - extract the flow_keys struct and return it > + * @net: associated network namespace, derived from @skb if NULL > * @skb: sk_buff to extract the flow from, can be NULL if the rest > are specified > * @flow_dissector: list of keys to dissect > * @target_container: target structure to put dissected values into > @@ -738,7 +739,8 @@ bool bpf_flow_dissect(struct bpf_prog *prog, > struct bpf_flow_dissector *ctx, > * > * Caller must take care of zeroing target container memory. > */ > -bool __skb_flow_dissect(const struct sk_buff *skb, > +bool __skb_flow_dissect(const struct net *net, > + const struct sk_buff *skb, > struct flow_dissector *flow_dissector, > void *target_container, > void *data, __be16 proto, int nhoff, int hlen, LGTM, Reviewed-by: Saeed Mahameed <saeedm@mellanox.com> Side Note: it is not this patch's fault, but I think that there is lots of room for improvement in __skb_flow_dissect parameters set, it seems that the function can receives two separate sets of parameters and each set is only used when a valid skb is passed, while the other set is used when skb is null but data ptr isn't, this makes this function very hard to read and track it's flow. My 2 cent is that we need two versions of __skb_flow_dissect, one that uses skb and the other uses data pointer, and the skb version can perfectly use the "data" ptr version, it could be a hard re-factoring task, but i think it is doable.
On Mon, Apr 22, 2019 at 11:08 AM Saeed Mahameed <saeedm@mellanox.com> wrote: > > On Mon, 2019-04-22 at 08:55 -0700, Stanislav Fomichev wrote: > > This new argument will be used in the next patches for the > > eth_get_headlen use case. eth_get_headlen calls flow dissector > > with only data (without skb) so there is currently no way to > > pull attached BPF flow dissector program. With this new argument, > > we can amend the callers to explicitly pass network namespace > > so we can use attached BPF program. > > > > Signed-off-by: Stanislav Fomichev <sdf@google.com> > > --- > > include/linux/skbuff.h | 19 +++++++++++-------- > > net/core/flow_dissector.c | 27 +++++++++++++++++---------- > > net/ethernet/eth.c | 5 +++-- > > 3 files changed, 31 insertions(+), 20 deletions(-) > > > > diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h > > index beaedd487be1..ee7d1a85f624 100644 > > --- a/include/linux/skbuff.h > > +++ b/include/linux/skbuff.h > > @@ -1284,7 +1284,8 @@ bool __skb_flow_bpf_dissect(struct bpf_prog > > *prog, > > const struct sk_buff *skb, > > struct flow_dissector *flow_dissector, > > struct bpf_flow_keys *flow_keys); > > -bool __skb_flow_dissect(const struct sk_buff *skb, > > +bool __skb_flow_dissect(const struct net *net, > > + const struct sk_buff *skb, > > struct flow_dissector *flow_dissector, > > void *target_container, > > void *data, __be16 proto, int nhoff, int hlen, > > @@ -1294,8 +1295,8 @@ static inline bool skb_flow_dissect(const > > struct sk_buff *skb, > > struct flow_dissector > > *flow_dissector, > > void *target_container, unsigned > > int flags) > > { > > - return __skb_flow_dissect(skb, flow_dissector, > > target_container, > > - NULL, 0, 0, 0, flags); > > + return __skb_flow_dissect(NULL, skb, flow_dissector, > > + target_container, NULL, 0, 0, 0, > > flags); > > } > > > > static inline bool skb_flow_dissect_flow_keys(const struct sk_buff > > *skb, > > @@ -1303,18 +1304,19 @@ static inline bool > > skb_flow_dissect_flow_keys(const struct sk_buff *skb, > > unsigned int flags) > > { > > memset(flow, 0, sizeof(*flow)); > > - return __skb_flow_dissect(skb, &flow_keys_dissector, flow, > > - NULL, 0, 0, 0, flags); > > + return __skb_flow_dissect(NULL, skb, &flow_keys_dissector, > > + flow, NULL, 0, 0, 0, flags); > > } > > > > static inline bool > > -skb_flow_dissect_flow_keys_basic(const struct sk_buff *skb, > > +skb_flow_dissect_flow_keys_basic(const struct net *net, > > + const struct sk_buff *skb, > > struct flow_keys_basic *flow, void > > *data, > > __be16 proto, int nhoff, int hlen, > > unsigned int flags) > > { > > memset(flow, 0, sizeof(*flow)); > > - return __skb_flow_dissect(skb, &flow_keys_basic_dissector, > > flow, > > + return __skb_flow_dissect(net, skb, &flow_keys_basic_dissector, > > flow, > > data, proto, nhoff, hlen, flags); > > } > > > > @@ -2494,7 +2496,8 @@ static inline void > > skb_probe_transport_header(struct sk_buff *skb) > > if (skb_transport_header_was_set(skb)) > > return; > > > > - if (skb_flow_dissect_flow_keys_basic(skb, &keys, NULL, 0, 0, 0, > > 0)) > > + if (skb_flow_dissect_flow_keys_basic(NULL, skb, &keys, > > + NULL, 0, 0, 0, 0)) > > skb_set_transport_header(skb, keys.control.thoff); > > } > > > > diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c > > index ef6d9443cc75..f32c7e737fc6 100644 > > --- a/net/core/flow_dissector.c > > +++ b/net/core/flow_dissector.c > > @@ -722,6 +722,7 @@ bool bpf_flow_dissect(struct bpf_prog *prog, > > struct bpf_flow_dissector *ctx, > > > > /** > > * __skb_flow_dissect - extract the flow_keys struct and return it > > + * @net: associated network namespace, derived from @skb if NULL > > * @skb: sk_buff to extract the flow from, can be NULL if the rest > > are specified > > * @flow_dissector: list of keys to dissect > > * @target_container: target structure to put dissected values into > > @@ -738,7 +739,8 @@ bool bpf_flow_dissect(struct bpf_prog *prog, > > struct bpf_flow_dissector *ctx, > > * > > * Caller must take care of zeroing target container memory. > > */ > > -bool __skb_flow_dissect(const struct sk_buff *skb, > > +bool __skb_flow_dissect(const struct net *net, > > + const struct sk_buff *skb, > > struct flow_dissector *flow_dissector, > > void *target_container, > > void *data, __be16 proto, int nhoff, int hlen, > > LGTM, > > Reviewed-by: Saeed Mahameed <saeedm@mellanox.com> > > Side Note: it is not this patch's fault, but I think that there is lots > of room for improvement in __skb_flow_dissect parameters set, it seems > that the function can receives two separate sets of parameters and each > set is only used when a valid skb is passed, while the other set is > used when skb is null but data ptr isn't, this makes this function very > hard to read and track it's flow. > > My 2 cent is that we need two versions of __skb_flow_dissect, one that > uses skb and the other uses data pointer, and the skb version can > perfectly use the "data" ptr version, it could be a hard re-factoring > task, but i think it is doable. Agreed, the only problem with separating those two is __skb_header_pointer which is occasionally called to fetch more data from the skb frags (for both data!=NULL and skb!=NULL cases). I was thinking about changing the order of input params to move skb to the end (so it looks more optional) and to move all this !data initialization into a wrapper. I might look into this at some point..
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index beaedd487be1..ee7d1a85f624 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -1284,7 +1284,8 @@ bool __skb_flow_bpf_dissect(struct bpf_prog *prog, const struct sk_buff *skb, struct flow_dissector *flow_dissector, struct bpf_flow_keys *flow_keys); -bool __skb_flow_dissect(const struct sk_buff *skb, +bool __skb_flow_dissect(const struct net *net, + const struct sk_buff *skb, struct flow_dissector *flow_dissector, void *target_container, void *data, __be16 proto, int nhoff, int hlen, @@ -1294,8 +1295,8 @@ static inline bool skb_flow_dissect(const struct sk_buff *skb, struct flow_dissector *flow_dissector, void *target_container, unsigned int flags) { - return __skb_flow_dissect(skb, flow_dissector, target_container, - NULL, 0, 0, 0, flags); + return __skb_flow_dissect(NULL, skb, flow_dissector, + target_container, NULL, 0, 0, 0, flags); } static inline bool skb_flow_dissect_flow_keys(const struct sk_buff *skb, @@ -1303,18 +1304,19 @@ static inline bool skb_flow_dissect_flow_keys(const struct sk_buff *skb, unsigned int flags) { memset(flow, 0, sizeof(*flow)); - return __skb_flow_dissect(skb, &flow_keys_dissector, flow, - NULL, 0, 0, 0, flags); + return __skb_flow_dissect(NULL, skb, &flow_keys_dissector, + flow, NULL, 0, 0, 0, flags); } static inline bool -skb_flow_dissect_flow_keys_basic(const struct sk_buff *skb, +skb_flow_dissect_flow_keys_basic(const struct net *net, + const struct sk_buff *skb, struct flow_keys_basic *flow, void *data, __be16 proto, int nhoff, int hlen, unsigned int flags) { memset(flow, 0, sizeof(*flow)); - return __skb_flow_dissect(skb, &flow_keys_basic_dissector, flow, + return __skb_flow_dissect(net, skb, &flow_keys_basic_dissector, flow, data, proto, nhoff, hlen, flags); } @@ -2494,7 +2496,8 @@ static inline void skb_probe_transport_header(struct sk_buff *skb) if (skb_transport_header_was_set(skb)) return; - if (skb_flow_dissect_flow_keys_basic(skb, &keys, NULL, 0, 0, 0, 0)) + if (skb_flow_dissect_flow_keys_basic(NULL, skb, &keys, + NULL, 0, 0, 0, 0)) skb_set_transport_header(skb, keys.control.thoff); } diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c index ef6d9443cc75..f32c7e737fc6 100644 --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -722,6 +722,7 @@ bool bpf_flow_dissect(struct bpf_prog *prog, struct bpf_flow_dissector *ctx, /** * __skb_flow_dissect - extract the flow_keys struct and return it + * @net: associated network namespace, derived from @skb if NULL * @skb: sk_buff to extract the flow from, can be NULL if the rest are specified * @flow_dissector: list of keys to dissect * @target_container: target structure to put dissected values into @@ -738,7 +739,8 @@ bool bpf_flow_dissect(struct bpf_prog *prog, struct bpf_flow_dissector *ctx, * * Caller must take care of zeroing target container memory. */ -bool __skb_flow_dissect(const struct sk_buff *skb, +bool __skb_flow_dissect(const struct net *net, + const struct sk_buff *skb, struct flow_dissector *flow_dissector, void *target_container, void *data, __be16 proto, int nhoff, int hlen, @@ -797,13 +799,17 @@ bool __skb_flow_dissect(const struct sk_buff *skb, struct bpf_prog *attached = NULL; rcu_read_lock(); + if (!net) { + if (skb->dev) + net = dev_net(skb->dev); + else if (skb->sk) + net = sock_net(skb->sk); + else + WARN_ON_ONCE(1); + } - if (skb->dev) - attached = rcu_dereference(dev_net(skb->dev)->flow_dissector_prog); - else if (skb->sk) - attached = rcu_dereference(sock_net(skb->sk)->flow_dissector_prog); - else - WARN_ON_ONCE(1); + if (net) + attached = rcu_dereference(net->flow_dissector_prog); if (attached) { ret = __skb_flow_bpf_dissect(attached, skb, @@ -1405,8 +1411,8 @@ u32 __skb_get_hash_symmetric(const struct sk_buff *skb) __flow_hash_secret_init(); memset(&keys, 0, sizeof(keys)); - __skb_flow_dissect(skb, &flow_keys_dissector_symmetric, &keys, - NULL, 0, 0, 0, + __skb_flow_dissect(NULL, skb, &flow_keys_dissector_symmetric, + &keys, NULL, 0, 0, 0, FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL); return __flow_hash_from_keys(&keys, hashrnd); @@ -1507,7 +1513,8 @@ u32 skb_get_poff(const struct sk_buff *skb) { struct flow_keys_basic keys; - if (!skb_flow_dissect_flow_keys_basic(skb, &keys, NULL, 0, 0, 0, 0)) + if (!skb_flow_dissect_flow_keys_basic(NULL, skb, &keys, + NULL, 0, 0, 0, 0)) return 0; return __skb_get_poff(skb, skb->data, &keys, skb_headlen(skb)); diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c index f7a3d7a171c7..1e439549c419 100644 --- a/net/ethernet/eth.c +++ b/net/ethernet/eth.c @@ -136,8 +136,9 @@ u32 eth_get_headlen(void *data, unsigned int len) return len; /* parse any remaining L2/L3 headers, check for L4 */ - if (!skb_flow_dissect_flow_keys_basic(NULL, &keys, data, eth->h_proto, - sizeof(*eth), len, flags)) + if (!skb_flow_dissect_flow_keys_basic(NULL, NULL, &keys, data, + eth->h_proto, sizeof(*eth), + len, flags)) return max_t(u32, keys.control.thoff, sizeof(*eth)); /* parse for any L4 headers */
This new argument will be used in the next patches for the eth_get_headlen use case. eth_get_headlen calls flow dissector with only data (without skb) so there is currently no way to pull attached BPF flow dissector program. With this new argument, we can amend the callers to explicitly pass network namespace so we can use attached BPF program. Signed-off-by: Stanislav Fomichev <sdf@google.com> --- include/linux/skbuff.h | 19 +++++++++++-------- net/core/flow_dissector.c | 27 +++++++++++++++++---------- net/ethernet/eth.c | 5 +++-- 3 files changed, 31 insertions(+), 20 deletions(-)