From e420bed025071a623d2720a92bc2245c84757ecb Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Wed, 19 Jul 2023 16:08:52 +0200 Subject: bpf: Add fd-based tcx multi-prog infra with link support This work refactors and adds a lightweight extension ("tcx") to the tc BPF ingress and egress data path side for allowing BPF program management based on fds via bpf() syscall through the newly added generic multi-prog API. The main goal behind this work which we also presented at LPC [0] last year and a recent update at LSF/MM/BPF this year [3] is to support long-awaited BPF link functionality for tc BPF programs, which allows for a model of safe ownership and program detachment. Given the rise in tc BPF users in cloud native environments, this becomes necessary to avoid hard to debug incidents either through stale leftover programs or 3rd party applications accidentally stepping on each others toes. As a recap, a BPF link represents the attachment of a BPF program to a BPF hook point. The BPF link holds a single reference to keep BPF program alive. Moreover, hook points do not reference a BPF link, only the application's fd or pinning does. A BPF link holds meta-data specific to attachment and implements operations for link creation, (atomic) BPF program update, detachment and introspection. The motivation for BPF links for tc BPF programs is multi-fold, for example: - From Meta: "It's especially important for applications that are deployed fleet-wide and that don't "control" hosts they are deployed to. If such application crashes and no one notices and does anything about that, BPF program will keep running draining resources or even just, say, dropping packets. We at FB had outages due to such permanent BPF attachment semantics. With fd-based BPF link we are getting a framework, which allows safe, auto-detachable behavior by default, unless application explicitly opts in by pinning the BPF link." [1] - From Cilium-side the tc BPF programs we attach to host-facing veth devices and phys devices build the core datapath for Kubernetes Pods, and they implement forwarding, load-balancing, policy, EDT-management, etc, within BPF. Currently there is no concept of 'safe' ownership, e.g. we've recently experienced hard-to-debug issues in a user's staging environment where another Kubernetes application using tc BPF attached to the same prio/handle of cls_bpf, accidentally wiping all Cilium-based BPF programs from underneath it. The goal is to establish a clear/safe ownership model via links which cannot accidentally be overridden. [0,2] BPF links for tc can co-exist with non-link attachments, and the semantics are in line also with XDP links: BPF links cannot replace other BPF links, BPF links cannot replace non-BPF links, non-BPF links cannot replace BPF links and lastly only non-BPF links can replace non-BPF links. In case of Cilium, this would solve mentioned issue of safe ownership model as 3rd party applications would not be able to accidentally wipe Cilium programs, even if they are not BPF link aware. Earlier attempts [4] have tried to integrate BPF links into core tc machinery to solve cls_bpf, which has been intrusive to the generic tc kernel API with extensions only specific to cls_bpf and suboptimal/complex since cls_bpf could be wiped from the qdisc also. Locking a tc BPF program in place this way, is getting into layering hacks given the two object models are vastly different. We instead implemented the tcx (tc 'express') layer which is an fd-based tc BPF attach API, so that the BPF link implementation blends in naturally similar to other link types which are fd-based and without the need for changing core tc internal APIs. BPF programs for tc can then be successively migrated from classic cls_bpf to the new tc BPF link without needing to change the program's source code, just the BPF loader mechanics for attaching is sufficient. For the current tc framework, there is no change in behavior with this change and neither does this change touch on tc core kernel APIs. The gist of this patch is that the ingress and egress hook have a lightweight, qdisc-less extension for BPF to attach its tc BPF programs, in other words, a minimal entry point for tc BPF. The name tcx has been suggested from discussion of earlier revisions of this work as a good fit, and to more easily differ between the classic cls_bpf attachment and the fd-based one. For the ingress and egress tcx points, the device holds a cache-friendly array with program pointers which is separated from control plane (slow-path) data. Earlier versions of this work used priority to determine ordering and expression of dependencies similar as with classic tc, but it was challenged that for something more future-proof a better user experience is required. Hence this resulted in the design and development of the generic attach/detach/query API for multi-progs. See prior patch with its discussion on the API design. tcx is the first user and later we plan to integrate also others, for example, one candidate is multi-prog support for XDP which would benefit and have the same 'look and feel' from API perspective. The goal with tcx is to have maximum compatibility to existing tc BPF programs, so they don't need to be rewritten specifically. Compatibility to call into classic tcf_classify() is also provided in order to allow successive migration or both to cleanly co-exist where needed given its all one logical tc layer and the tcx plus classic tc cls/act build one logical overall processing pipeline. tcx supports the simplified return codes TCX_NEXT which is non-terminating (go to next program) and terminating ones with TCX_PASS, TCX_DROP, TCX_REDIRECT. The fd-based API is behind a static key, so that when unused the code is also not entered. The struct tcx_entry's program array is currently static, but could be made dynamic if necessary at a point in future. The a/b pair swap design has been chosen so that for detachment there are no allocations which otherwise could fail. The work has been tested with tc-testing selftest suite which all passes, as well as the tc BPF tests from the BPF CI, and also with Cilium's L4LB. Thanks also to Nikolay Aleksandrov and Martin Lau for in-depth early reviews of this work. [0] https://lpc.events/event/16/contributions/1353/ [1] https://lore.kernel.org/bpf/CAEf4BzbokCJN33Nw_kg82sO=xppXnKWEncGTWCTB9vGCmLB6pw@mail.gmail.com [2] https://colocatedeventseu2023.sched.com/event/1Jo6O/tales-from-an-ebpf-programs-murder-mystery-hemanth-malla-guillaume-fournier-datadog [3] http://vger.kernel.org/bpfconf2023_material/tcx_meta_netdev_borkmann.pdf [4] https://lore.kernel.org/bpf/20210604063116.234316-1-memxor@gmail.com Signed-off-by: Daniel Borkmann Acked-by: Jakub Kicinski Link: https://lore.kernel.org/r/20230719140858.13224-3-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov --- include/linux/skbuff.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux/skbuff.h') diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 91ed66952580..ed83f1c5fc1f 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -944,7 +944,7 @@ struct sk_buff { __u8 __mono_tc_offset[0]; /* public: */ __u8 mono_delivery_time:1; /* See SKB_MONO_DELIVERY_TIME_MASK */ -#ifdef CONFIG_NET_CLS_ACT +#ifdef CONFIG_NET_XGRESS __u8 tc_at_ingress:1; /* See TC_AT_INGRESS_MASK */ __u8 tc_skip_classify:1; #endif @@ -993,7 +993,7 @@ struct sk_buff { __u8 csum_not_inet:1; #endif -#ifdef CONFIG_NET_SCHED +#if defined(CONFIG_NET_SCHED) || defined(CONFIG_NET_XGRESS) __u16 tc_index; /* traffic control index */ #endif -- cgit v1.2.3 From 6f5a630d7c57cd79b1f526a95e757311e32d41e5 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Tue, 18 Jul 2023 16:40:21 -0700 Subject: bpf, net: Introduce skb_pointer_if_linear(). Network drivers always call skb_header_pointer() with non-null buffer. Remove !buffer check to prevent accidental misuse of skb_header_pointer(). Introduce skb_pointer_if_linear() instead. Reported-by: Jakub Kicinski Acked-by: Jakub Kicinski Link: https://lore.kernel.org/r/20230718234021.43640-1-alexei.starovoitov@gmail.com Signed-off-by: Alexei Starovoitov --- include/linux/skbuff.h | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'include/linux/skbuff.h') diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index ed83f1c5fc1f..faaba050f843 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -4023,7 +4023,7 @@ __skb_header_pointer(const struct sk_buff *skb, int offset, int len, if (likely(hlen - offset >= len)) return (void *)data + offset; - if (!skb || !buffer || unlikely(skb_copy_bits(skb, offset, buffer, len) < 0)) + if (!skb || unlikely(skb_copy_bits(skb, offset, buffer, len) < 0)) return NULL; return buffer; @@ -4036,6 +4036,14 @@ skb_header_pointer(const struct sk_buff *skb, int offset, int len, void *buffer) skb_headlen(skb), buffer); } +static inline void * __must_check +skb_pointer_if_linear(const struct sk_buff *skb, int offset, int len) +{ + if (likely(skb_headlen(skb) - offset >= len)) + return skb->data + offset; + return NULL; +} + /** * skb_needs_linearize - check if we need to linearize a given skb * depending on the given device features. -- cgit v1.2.3 From 2303fae130640874823ea1bc7ec65c3cd074a7eb Mon Sep 17 00:00:00 2001 From: Peter Seiderer Date: Mon, 24 Jul 2023 18:22:55 +0200 Subject: net: skbuff: remove unused HAVE_HW_TIME_STAMP feature define Remove unused HAVE_HW_TIME_STAMP feature define (introduced by commit ac45f602ee3d ("net: infrastructure for hardware time stamping"). Signed-off-by: Peter Seiderer Reviewed-by: Simon Horman Signed-off-by: David S. Miller --- include/linux/skbuff.h | 2 -- 1 file changed, 2 deletions(-) (limited to 'include/linux/skbuff.h') diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index faaba050f843..16a49ba534e4 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -441,8 +441,6 @@ static inline bool skb_frag_must_loop(struct page *p) copied += p_len, p++, p_off = 0, \ p_len = min_t(u32, f_len - copied, PAGE_SIZE)) \ -#define HAVE_HW_TIME_STAMP - /** * struct skb_shared_hwtstamps - hardware time stamps * @hwtstamp: hardware time stamp transformed into duration -- cgit v1.2.3 From a9ca9f9ceff382b58b488248f0c0da9e157f5d06 Mon Sep 17 00:00:00 2001 From: Yunsheng Lin Date: Fri, 4 Aug 2023 20:05:24 +0200 Subject: page_pool: split types and declarations from page_pool.h Split types and pure function declarations from page_pool.h and add them in page_page/types.h, so that C sources can include page_pool.h and headers should generally only include page_pool/types.h as suggested by jakub. Rename page_pool.h to page_pool/helpers.h to have both in one place. Signed-off-by: Yunsheng Lin Suggested-by: Jakub Kicinski Signed-off-by: Alexander Lobakin Reviewed-by: Alexander Duyck Link: https://lore.kernel.org/r/20230804180529.2483231-2-aleksander.lobakin@intel.com [Jakub: change microsoft/mana, fix kdoc paths in Documentation] Signed-off-by: Jakub Kicinski --- include/linux/skbuff.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/skbuff.h') diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 16a49ba534e4..888e3d7e74c1 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -32,7 +32,7 @@ #include #include #include -#include +#include #if IS_ENABLED(CONFIG_NF_CONNTRACK) #include #endif -- cgit v1.2.3 From 75eaf63ea7afeafd026ffef03bdc69e31f10829b Mon Sep 17 00:00:00 2001 From: Alexander Lobakin Date: Fri, 4 Aug 2023 20:05:25 +0200 Subject: net: skbuff: don't include to Currently, touching triggers a rebuild of more than half of the kernel. That's because it's included in . And each new include to page_pool/types.h adds more [useless] data for the toolchain to process per each source file from that pile. In commit 6a5bcd84e886 ("page_pool: Allow drivers to hint on SKB recycling"), Matteo included it to be able to call a couple of functions defined there. Then, in commit 57f05bc2ab24 ("page_pool: keep pp info as long as page pool owns the page") one of the calls was removed, so only one was left. It's the call to page_pool_return_skb_page() in napi_frag_unref(). The function is external and doesn't have any dependencies. Having very niche page_pool_types.h included only for that looks like an overkill. As %PP_SIGNATURE is not local to page_pool.c (was only in the early submissions), nothing holds this function there. Teleport page_pool_return_skb_page() to skbuff.c, just next to the main consumer, skb_pp_recycle(), and rename it to napi_pp_put_page(), as it doesn't work with skbs at all and the former name tells nothing. The #if guards here are only to not compile and have it in the vmlinux when not needed -- both call sites are already guarded. Now, touching page_pool_types.h only triggers rebuilding of the drivers using it and a couple of core networking files. Suggested-by: Jakub Kicinski # make skbuff.h less heavy Suggested-by: Alexander Duyck # move to skbuff.c Signed-off-by: Alexander Lobakin Reviewed-by: Alexander Duyck Link: https://lore.kernel.org/r/20230804180529.2483231-3-aleksander.lobakin@intel.com Signed-off-by: Jakub Kicinski --- include/linux/skbuff.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'include/linux/skbuff.h') diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 888e3d7e74c1..aa57e2eca33b 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -32,7 +32,6 @@ #include #include #include -#include #if IS_ENABLED(CONFIG_NF_CONNTRACK) #include #endif @@ -3421,13 +3420,15 @@ static inline void skb_frag_ref(struct sk_buff *skb, int f) __skb_frag_ref(&skb_shinfo(skb)->frags[f]); } +bool napi_pp_put_page(struct page *page, bool napi_safe); + static inline void napi_frag_unref(skb_frag_t *frag, bool recycle, bool napi_safe) { struct page *page = skb_frag_page(frag); #ifdef CONFIG_PAGE_POOL - if (recycle && page_pool_return_skb_page(page, napi_safe)) + if (recycle && napi_pp_put_page(page, napi_safe)) return; #endif put_page(page); -- cgit v1.2.3 From 4025d3e73abde4f65f4b04d4b1d8449b00e31473 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 18 Aug 2023 09:40:39 +0000 Subject: net: add skb_queue_purge_reason and __skb_queue_purge_reason skb_queue_purge() and __skb_queue_purge() become wrappers around the new generic functions. New SKB_DROP_REASON_QUEUE_PURGE drop reason is added, but users can start adding more specific reasons. Signed-off-by: Eric Dumazet Reviewed-by: Simon Horman Signed-off-by: David S. Miller --- include/linux/skbuff.h | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-) (limited to 'include/linux/skbuff.h') diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index aa57e2eca33b..9aec136bc690 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -3149,20 +3149,35 @@ static inline int skb_orphan_frags_rx(struct sk_buff *skb, gfp_t gfp_mask) } /** - * __skb_queue_purge - empty a list + * __skb_queue_purge_reason - empty a list * @list: list to empty + * @reason: drop reason * * Delete all buffers on an &sk_buff list. Each buffer is removed from * the list and one reference dropped. This function does not take the * list lock and the caller must hold the relevant locks to use it. */ -static inline void __skb_queue_purge(struct sk_buff_head *list) +static inline void __skb_queue_purge_reason(struct sk_buff_head *list, + enum skb_drop_reason reason) { struct sk_buff *skb; + while ((skb = __skb_dequeue(list)) != NULL) - kfree_skb(skb); + kfree_skb_reason(skb, reason); +} + +static inline void __skb_queue_purge(struct sk_buff_head *list) +{ + __skb_queue_purge_reason(list, SKB_DROP_REASON_QUEUE_PURGE); +} + +void skb_queue_purge_reason(struct sk_buff_head *list, + enum skb_drop_reason reason); + +static inline void skb_queue_purge(struct sk_buff_head *list) +{ + skb_queue_purge_reason(list, SKB_DROP_REASON_QUEUE_PURGE); } -void skb_queue_purge(struct sk_buff_head *list); unsigned int skb_rbtree_purge(struct rb_root *root); -- cgit v1.2.3 From 0f158b32a9b146c9b86783efccfd9ed02c744623 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 18 Aug 2023 17:41:45 +0000 Subject: net: selectively purge error queue in IP_RECVERR / IPV6_RECVERR Setting IP_RECVERR and IPV6_RECVERR options to zero currently purges the socket error queue, which was probably not expected for zerocopy and tx_timestamp users. I discovered this issue while preparing commit 6b5f43ea0815 ("inet: move inet->recverr to inet->inet_flags"), I presume this change does not need to be backported to stable kernels. Add skb_errqueue_purge() helper to purge error messages only. Signed-off-by: Eric Dumazet Cc: Willem de Bruijn Cc: Soheil Hassas Yeganeh Reviewed-by: Willem de Bruijn Signed-off-by: David S. Miller --- include/linux/skbuff.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/skbuff.h') diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 9aec136bc690..4174c4b82d13 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -3180,6 +3180,7 @@ static inline void skb_queue_purge(struct sk_buff_head *list) } unsigned int skb_rbtree_purge(struct rb_root *root); +void skb_errqueue_purge(struct sk_buff_head *list); void *__netdev_alloc_frag_align(unsigned int fragsz, unsigned int align_mask); -- cgit v1.2.3