From patchwork Thu Feb 23 01:12:33 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kui-Feng Lee X-Patchwork-Id: 13149752 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D7350C61DA4 for ; Thu, 23 Feb 2023 01:12:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232787AbjBWBMz (ORCPT ); Wed, 22 Feb 2023 20:12:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53618 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232785AbjBWBMy (ORCPT ); Wed, 22 Feb 2023 20:12:54 -0500 Received: from mx0a-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BA0DD44AA for ; Wed, 22 Feb 2023 17:12:51 -0800 (PST) Received: from pps.filterd (m0089730.ppops.net [127.0.0.1]) by m0089730.ppops.net (8.17.1.19/8.17.1.19) with ESMTP id 31N0L8Rg028753 for ; Wed, 22 Feb 2023 17:12:51 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=meta.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=s2048-2021-q4; bh=Zbd/te8usnZP0uNPZmt1i2+H89k3iv3PDQU7aFpxgkc=; b=e+BwYBIAolrdnOWe3cQhLd3NHPBXycC1B57JE4uTt1xoEzTnzZNcxBrVddJou/Im7qEC NjTOst93jLZCdnjc9DMFUW7ENaXFS9AVJZsTSRS1qLs+wULHnpRkvwx69anCE2xOniha kUHEr+cv1a6GDhXK+O9JBo3ZXnCq2VEY/t/IVyzH7iC/gCJCVwnndMTIv9eRiREjU9De Nv1+lZ3gmx/7uPRlHAtAtl1UrfzkZr2lPT05zXDnwYPPHm/d7tTPvzFCbInsuIpqIFsc 0yK/jaP1ITk8qTOXSxw5RuMoN8suq9t0QTBCM3VPj1XNMpD5T5OZLN6d5blbp7iPLFmb jQ== Received: from maileast.thefacebook.com ([163.114.130.16]) by m0089730.ppops.net (PPS) with ESMTPS id 3nwdy9xs6n-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Wed, 22 Feb 2023 17:12:50 -0800 Received: from twshared16996.15.frc2.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:82::e) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.17; Wed, 22 Feb 2023 17:12:48 -0800 Received: by devbig931.frc1.facebook.com (Postfix, from userid 460691) id 7A3935BD8CBD; Wed, 22 Feb 2023 17:12:40 -0800 (PST) From: Kui-Feng Lee To: , , , , , , CC: Kui-Feng Lee Subject: [PATCH bpf-next v2 1/6] bpf: Create links for BPF struct_ops maps. Date: Wed, 22 Feb 2023 17:12:33 -0800 Message-ID: <20230223011238.12313-2-kuifeng@meta.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20230223011238.12313-1-kuifeng@meta.com> References: <20230223011238.12313-1-kuifeng@meta.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-GUID: dGx3afYLazaIbLlxrdG9TAyox3sYT_hI X-Proofpoint-ORIG-GUID: dGx3afYLazaIbLlxrdG9TAyox3sYT_hI X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.930,Hydra:6.0.562,FMLib:17.11.170.22 definitions=2023-02-22_12,2023-02-22_02,2023-02-09_01 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net BPF struct_ops maps are employed directly to register TCP Congestion Control algorithms. Unlike other BPF programs that terminate when their links gone, the struct_ops program reduces its refcount solely upon death of its FD. The link of a BPF struct_ops map provides a uniform experience akin to other types of BPF programs. bpf_links are responsible for registering their associated struct_ops. You can only use a struct_ops that has the BPF_F_LINK flag set to create a bpf_link, while a structs without this flag behaves in the same manner as before and is registered upon updating its value. Signed-off-by: Kui-Feng Lee --- include/linux/bpf.h | 11 + include/uapi/linux/bpf.h | 12 +- kernel/bpf/bpf_struct_ops.c | 376 ++++++++++++++++++++++++++++++--- kernel/bpf/syscall.c | 26 ++- tools/include/uapi/linux/bpf.h | 12 +- 5 files changed, 402 insertions(+), 35 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 8b5d0b4c4ada..9d6fd874e5ee 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1395,6 +1395,11 @@ struct bpf_link { struct work_struct work; }; +struct bpf_struct_ops_link { + struct bpf_link link; + struct bpf_map __rcu *map; +}; + struct bpf_link_ops { void (*release)(struct bpf_link *link); void (*dealloc)(struct bpf_link *link); @@ -1961,6 +1966,7 @@ int bpf_link_new_fd(struct bpf_link *link); struct file *bpf_link_new_file(struct bpf_link *link, int *reserved_fd); struct bpf_link *bpf_link_get_from_fd(u32 ufd); struct bpf_link *bpf_link_get_curr_or_next(u32 *id); +int bpf_struct_ops_link_create(union bpf_attr *attr); int bpf_obj_pin_user(u32 ufd, const char __user *pathname); int bpf_obj_get_user(const char __user *pathname, int flags); @@ -2305,6 +2311,11 @@ static inline void bpf_link_put(struct bpf_link *link) { } +static inline int bpf_struct_ops_link_create(union bpf_attr *attr) +{ + return -EOPNOTSUPP; +} + static inline int bpf_obj_get_user(const char __user *pathname, int flags) { return -EOPNOTSUPP; diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 17afd2b35ee5..cd0ff39981e8 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1033,6 +1033,7 @@ enum bpf_attach_type { BPF_PERF_EVENT, BPF_TRACE_KPROBE_MULTI, BPF_LSM_CGROUP, + BPF_STRUCT_OPS, __MAX_BPF_ATTACH_TYPE }; @@ -1266,6 +1267,9 @@ enum { /* Create a map that is suitable to be an inner map with dynamic max entries */ BPF_F_INNER_MAP = (1U << 12), + +/* Create a map that will be registered/unregesitered by the backed bpf_link */ + BPF_F_LINK = (1U << 13), }; /* Flags for BPF_PROG_QUERY. */ @@ -1507,7 +1511,10 @@ union bpf_attr { } task_fd_query; struct { /* struct used by BPF_LINK_CREATE command */ - __u32 prog_fd; /* eBPF program to attach */ + union { + __u32 prog_fd; /* eBPF program to attach */ + __u32 map_fd; /* eBPF struct_ops to attach */ + }; union { __u32 target_fd; /* object to attach to */ __u32 target_ifindex; /* target ifindex */ @@ -6354,6 +6361,9 @@ struct bpf_link_info { struct { __u32 ifindex; } xdp; + struct { + __u32 map_id; + } struct_ops; }; } __attribute__((aligned(8))); diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c index ece9870cab68..cfc69033c1b8 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -14,8 +14,10 @@ enum bpf_struct_ops_state { BPF_STRUCT_OPS_STATE_INIT, + BPF_STRUCT_OPS_STATE_UNREG, BPF_STRUCT_OPS_STATE_INUSE, BPF_STRUCT_OPS_STATE_TOBEFREE, + BPF_STRUCT_OPS_STATE_TOBEUNREG, }; #define BPF_STRUCT_OPS_COMMON_VALUE \ @@ -58,6 +60,8 @@ struct bpf_struct_ops_map { struct bpf_struct_ops_value kvalue; }; +static DEFINE_MUTEX(update_mutex); + #define VALUE_PREFIX "bpf_struct_ops_" #define VALUE_PREFIX_LEN (sizeof(VALUE_PREFIX) - 1) @@ -253,22 +257,23 @@ int bpf_struct_ops_map_sys_lookup_elem(struct bpf_map *map, void *key, if (unlikely(*(u32 *)key != 0)) return -ENOENT; + mutex_lock(&st_map->lock); + kvalue = &st_map->kvalue; - /* Pair with smp_store_release() during map_update */ state = smp_load_acquire(&kvalue->state); if (state == BPF_STRUCT_OPS_STATE_INIT) { memset(value, 0, map->value_size); + mutex_unlock(&st_map->lock); return 0; } - /* No lock is needed. state and refcnt do not need - * to be updated together under atomic context. - */ uvalue = value; memcpy(uvalue, st_map->uvalue, map->value_size); uvalue->state = state; refcount_set(&uvalue->refcnt, refcount_read(&kvalue->refcnt)); + mutex_unlock(&st_map->lock); + return 0; } @@ -349,6 +354,150 @@ int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_links *tlinks, model, flags, tlinks, NULL); } +/* + * Maintain the state of kvalue. + * + * For a struct_ops that has no link, its state diagram is + * + * INIT ----> INUSE --> TOBEFREE + * ^ | + * | (refcnt == 0) | + * +---------------------+ + * + * For a struct_ops that has a link (BPF_F_LINK), its state diagram is + * + * (refcnt == 0) + * +-----------------------+ + * | | + * V | + * INIT ---> UNREG -+--> INUSE --> TOBEUNREG + * ^ | + * | V + * +---------- TOBEFREE + * (refcnt == 0) + * + * After transiting to the INUSE state of a struct_ops, the refcnt of + * its kvalue is set to 1. + * + * After transiting from the INUSE state of a struct_ops, the caller + * should decrease the refcnt of its kvalue by 1 by calling + * bpf_struct_ops_put(). + * + * TOBEFREE and TOBEUNREG are in a grace period, waiting for other + * tasks holding references of the struct_ops. When the refcnt drops + * from 1 to 0, TOBEFREE and TOBEUNREG are transited to INIT and UNREG + * respectively. + * + * It is safe to assume that there will be no registration race + * conditions after a task transits the same struct_ops to INUSE, + * TOBEFREE and TOBEUNREG states. The task is able to register or + * unregister the struct_ops without the need for any additional + * synchronization. + */ +static int bpf_struct_ops_transit_state(struct bpf_struct_ops_map *st_map, + enum bpf_struct_ops_state src, + enum bpf_struct_ops_state dst) +{ + int old_state; + + switch (src) { + case BPF_STRUCT_OPS_STATE_INIT: + if (dst != BPF_STRUCT_OPS_STATE_INUSE && + dst != BPF_STRUCT_OPS_STATE_UNREG) + return -EINVAL; + + old_state = cmpxchg(&st_map->kvalue.state, src, dst); + if (old_state != src) + break; + + if (dst == BPF_STRUCT_OPS_STATE_INUSE) + refcount_set(&st_map->kvalue.refcnt, 1); + break; + + case BPF_STRUCT_OPS_STATE_UNREG: + if (dst != BPF_STRUCT_OPS_STATE_INUSE && + dst != BPF_STRUCT_OPS_STATE_TOBEFREE) + return -EINVAL; + + old_state = cmpxchg(&st_map->kvalue.state, src, dst); + if (old_state != src) + break; + + if (dst == BPF_STRUCT_OPS_STATE_INUSE) + refcount_set(&st_map->kvalue.refcnt, 1); + else if (dst == BPF_STRUCT_OPS_STATE_TOBEFREE) + cmpxchg(&st_map->kvalue.state, dst, BPF_STRUCT_OPS_STATE_INIT); + break; + + case BPF_STRUCT_OPS_STATE_INUSE: + if (dst != BPF_STRUCT_OPS_STATE_TOBEFREE && + dst != BPF_STRUCT_OPS_STATE_TOBEUNREG) + return -EINVAL; + + old_state = cmpxchg(&st_map->kvalue.state, src, dst); + break; + + case BPF_STRUCT_OPS_STATE_TOBEFREE: + /* + * This transition should only be performed when the + * refcnt drops to 0 from 1. + */ + if (dst != BPF_STRUCT_OPS_STATE_INIT) + return -EINVAL; + old_state = cmpxchg(&st_map->kvalue.state, src, dst); + if (old_state != src) + break; + break; + + case BPF_STRUCT_OPS_STATE_TOBEUNREG: + /* + * This transition should only be performed when the + * refcnt drops to 0 from 1. + */ + if (dst != BPF_STRUCT_OPS_STATE_UNREG) + return -EINVAL; + old_state = cmpxchg(&st_map->kvalue.state, src, dst); + if (old_state != src) + return old_state; + break; + + default: + return -EOPNOTSUPP; + } + + return old_state; +} + +static int bpf_struct_ops_transit_state_check(struct bpf_struct_ops_map *st_map, + enum bpf_struct_ops_state src, + enum bpf_struct_ops_state dst) +{ + int err; + + err = bpf_struct_ops_transit_state(st_map, src, dst); + if (err < 0) + return err; + if (err != src) + return -EINVAL; + return 0; +} + +/* + * Restore the state of a struct_ops to UNREG from INUSE. + * + * It handles the case which a struct_ops transited to INUSE from + * UNREG successfully; somehow, need to rollback the struct_ops state. + */ +static void bpf_struct_ops_restore_unreg(struct bpf_struct_ops_map *st_map) +{ + struct bpf_struct_ops_value *kvalue; + + kvalue = &st_map->kvalue; + refcount_set(&kvalue->refcnt, 0); + /* Make sure the above change is seen before the state change. */ + smp_store_release(&kvalue->state, BPF_STRUCT_OPS_STATE_UNREG); +} + static int bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, void *value, u64 flags) { @@ -390,7 +539,11 @@ static int bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, mutex_lock(&st_map->lock); - if (kvalue->state != BPF_STRUCT_OPS_STATE_INIT) { + /* Make sure that all following changes are seen after the + * state value here. + */ + if (smp_load_acquire(&kvalue->state) >= BPF_STRUCT_OPS_STATE_INUSE || + refcount_read(&kvalue->refcnt)) { err = -EBUSY; goto unlock; } @@ -491,17 +644,21 @@ static int bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, *(unsigned long *)(udata + moff) = prog->aux->id; } - refcount_set(&kvalue->refcnt, 1); + if (st_map->map.map_flags & BPF_F_LINK) { + /* Let bpf_link handle registration & unregistration. */ + err = bpf_struct_ops_transit_state_check(st_map, BPF_STRUCT_OPS_STATE_INIT, + BPF_STRUCT_OPS_STATE_UNREG); + goto unlock; + } + bpf_map_inc(map); set_memory_rox((long)st_map->image, 1); err = st_ops->reg(kdata); if (likely(!err)) { - /* Pair with smp_load_acquire() during lookup_elem(). - * It ensures the above udata updates (e.g. prog->aux->id) - * can be seen once BPF_STRUCT_OPS_STATE_INUSE is set. - */ - smp_store_release(&kvalue->state, BPF_STRUCT_OPS_STATE_INUSE); + /* Infallible */ + bpf_struct_ops_transit_state(st_map, BPF_STRUCT_OPS_STATE_INIT, + BPF_STRUCT_OPS_STATE_INUSE); goto unlock; } @@ -526,28 +683,49 @@ static int bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, static int bpf_struct_ops_map_delete_elem(struct bpf_map *map, void *key) { - enum bpf_struct_ops_state prev_state; struct bpf_struct_ops_map *st_map; + int old_state; + int err = 0; st_map = (struct bpf_struct_ops_map *)map; - prev_state = cmpxchg(&st_map->kvalue.state, - BPF_STRUCT_OPS_STATE_INUSE, - BPF_STRUCT_OPS_STATE_TOBEFREE); - switch (prev_state) { + + old_state = bpf_struct_ops_transit_state(st_map, + (st_map->map.map_flags & BPF_F_LINK ? + BPF_STRUCT_OPS_STATE_UNREG : + BPF_STRUCT_OPS_STATE_INUSE), + BPF_STRUCT_OPS_STATE_TOBEFREE); + + if (old_state < 0) + return old_state; + + switch (old_state) { + case BPF_STRUCT_OPS_STATE_UNREG: + break; case BPF_STRUCT_OPS_STATE_INUSE: - st_map->st_ops->unreg(&st_map->kvalue.data); - if (refcount_dec_and_test(&st_map->kvalue.refcnt)) - bpf_map_put(map); - return 0; + if (st_map->map.map_flags & BPF_F_LINK) + err = -EBUSY; + else { + st_map->st_ops->unreg(&st_map->kvalue.data); + bpf_struct_ops_put(&st_map->kvalue.data); + } + break; case BPF_STRUCT_OPS_STATE_TOBEFREE: - return -EINPROGRESS; + err = -EINPROGRESS; + break; + case BPF_STRUCT_OPS_STATE_TOBEUNREG: + err = -EBUSY; + break; case BPF_STRUCT_OPS_STATE_INIT: - return -ENOENT; + err = -ENOENT; + break; default: WARN_ON_ONCE(1); /* Should never happen. Treat it as not found. */ - return -ENOENT; + err = -ENOENT; + break; } + + return err; } static void bpf_struct_ops_map_seq_show_elem(struct bpf_map *map, void *key, @@ -585,7 +763,7 @@ static void bpf_struct_ops_map_free(struct bpf_map *map) static int bpf_struct_ops_map_alloc_check(union bpf_attr *attr) { if (attr->key_size != sizeof(unsigned int) || attr->max_entries != 1 || - attr->map_flags || !attr->btf_vmlinux_value_type_id) + (attr->map_flags & ~BPF_F_LINK) || !attr->btf_vmlinux_value_type_id) return -EINVAL; return 0; } @@ -671,6 +849,15 @@ static void bpf_struct_ops_put_rcu(struct rcu_head *head) struct bpf_struct_ops_map *st_map; st_map = container_of(head, struct bpf_struct_ops_map, rcu); + + /* The struct_ops can be reused after a rcu grace period. */ + if (st_map->kvalue.state == BPF_STRUCT_OPS_STATE_TOBEFREE) + bpf_struct_ops_transit_state(st_map, BPF_STRUCT_OPS_STATE_TOBEFREE, + BPF_STRUCT_OPS_STATE_INIT); + else if (st_map->kvalue.state == BPF_STRUCT_OPS_STATE_TOBEUNREG) + bpf_struct_ops_transit_state(st_map, BPF_STRUCT_OPS_STATE_TOBEUNREG, + BPF_STRUCT_OPS_STATE_UNREG); + bpf_map_put(&st_map->map); } @@ -684,6 +871,7 @@ void bpf_struct_ops_put(const void *kdata) st_map = container_of(kvalue, struct bpf_struct_ops_map, kvalue); + /* The struct_ops's function may switch to another struct_ops. * * For example, bpf_tcp_cc_x->init() may switch to @@ -698,3 +886,143 @@ void bpf_struct_ops_put(const void *kdata) call_rcu(&st_map->rcu, bpf_struct_ops_put_rcu); } } + +static void bpf_struct_ops_map_link_dealloc(struct bpf_link *link) +{ + struct bpf_struct_ops_link *st_link; + struct bpf_struct_ops_map *st_map; + + st_link = container_of(link, struct bpf_struct_ops_link, link); + if (st_link->map) { + st_map = (struct bpf_struct_ops_map *)st_link->map; + bpf_struct_ops_transit_state(st_map, BPF_STRUCT_OPS_STATE_INUSE, + (st_map->map.map_flags & BPF_F_LINK ? + BPF_STRUCT_OPS_STATE_TOBEUNREG : + BPF_STRUCT_OPS_STATE_TOBEFREE)); + st_map->st_ops->unreg(&st_map->kvalue.data); + bpf_struct_ops_put(&st_map->kvalue.data); + } + kfree(st_link); +} + +static int bpf_struct_ops_map_link_detach(struct bpf_link *link) +{ + struct bpf_struct_ops_link *st_link; + struct bpf_struct_ops_map *st_map; + + mutex_lock(&update_mutex); + st_link = container_of(link, struct bpf_struct_ops_link, link); + st_map = container_of(st_link->map, struct bpf_struct_ops_map, map); + if (st_map) { + /* + * All chaning on st_link->map are protected by + * update_mutex. This ensures that the struct_ops is + * INUSE, and the state transition always success. + */ + rcu_assign_pointer(st_link->map, NULL); + bpf_struct_ops_transit_state(st_map, BPF_STRUCT_OPS_STATE_INUSE, + (st_map->map.map_flags & BPF_F_LINK ? + BPF_STRUCT_OPS_STATE_TOBEUNREG : + BPF_STRUCT_OPS_STATE_TOBEFREE)); + st_map->st_ops->unreg(&st_map->kvalue.data); + bpf_struct_ops_put(&st_map->kvalue.data); + } + mutex_unlock(&update_mutex); + + return 0; +} + +static void bpf_struct_ops_map_link_show_fdinfo(const struct bpf_link *link, + struct seq_file *seq) +{ + struct bpf_struct_ops_link *st_link; + struct bpf_map *map; + + st_link = container_of(link, struct bpf_struct_ops_link, link); + rcu_read_lock_trace(); + map = rcu_dereference(st_link->map); + if (map) + seq_printf(seq, "map_id:\t%d\n", map->id); + rcu_read_unlock_trace(); +} + +static int bpf_struct_ops_map_link_fill_link_info(const struct bpf_link *link, + struct bpf_link_info *info) +{ + struct bpf_struct_ops_link *st_link; + struct bpf_map *map; + + st_link = container_of(link, struct bpf_struct_ops_link, link); + rcu_read_lock_trace(); + map = rcu_dereference(st_link->map); + if (map) + info->struct_ops.map_id = map->id; + rcu_read_unlock_trace(); + return 0; +} + +static const struct bpf_link_ops bpf_struct_ops_map_lops = { + .dealloc = bpf_struct_ops_map_link_dealloc, + .detach = bpf_struct_ops_map_link_detach, + .show_fdinfo = bpf_struct_ops_map_link_show_fdinfo, + .fill_link_info = bpf_struct_ops_map_link_fill_link_info, +}; + +int bpf_struct_ops_link_create(union bpf_attr *attr) +{ + struct bpf_struct_ops_link *link = NULL; + struct bpf_link_primer link_primer; + struct bpf_struct_ops_map *st_map; + struct bpf_map *map; + int err; + + map = bpf_map_get(attr->link_create.map_fd); + if (!map) + return -EINVAL; + + if (map->map_type != BPF_MAP_TYPE_STRUCT_OPS || !(map->map_flags & BPF_F_LINK)) { + err = -EINVAL; + goto err_out; + } + + link = kzalloc(sizeof(*link), GFP_USER); + if (!link) { + err = -ENOMEM; + goto err_out; + } + bpf_link_init(&link->link, BPF_LINK_TYPE_STRUCT_OPS, &bpf_struct_ops_map_lops, NULL); + link->map = map; + + st_map = (struct bpf_struct_ops_map *)map; + + err = bpf_struct_ops_transit_state_check(st_map, BPF_STRUCT_OPS_STATE_UNREG, + BPF_STRUCT_OPS_STATE_INUSE); + if (err) + goto err_out; + + err = bpf_link_prime(&link->link, &link_primer); + if (err) { + bpf_struct_ops_restore_unreg(st_map); + goto err_out; + } + + set_memory_rox((long)st_map->image, 1); + err = st_map->st_ops->reg(st_map->kvalue.data); + if (err) { + bpf_struct_ops_restore_unreg(st_map); + bpf_link_cleanup(&link_primer); + + set_memory_nx((long)st_map->image, 1); + set_memory_rw((long)st_map->image, 1); + goto err_out; + } + + + return bpf_link_settle(&link_primer); + +err_out: + bpf_map_put(map); + kfree(link); + return err; +} + diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index cda8d00f3762..2670de8dd0d4 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2735,10 +2735,11 @@ void bpf_link_inc(struct bpf_link *link) static void bpf_link_free(struct bpf_link *link) { bpf_link_free_id(link->id); + /* detach BPF program, clean up used resources */ if (link->prog) { - /* detach BPF program, clean up used resources */ link->ops->release(link); bpf_prog_put(link->prog); + /* The struct_ops links clean up map by them-selves. */ } /* free bpf_link and its containing memory */ link->ops->dealloc(link); @@ -2794,16 +2795,19 @@ static void bpf_link_show_fdinfo(struct seq_file *m, struct file *filp) const struct bpf_prog *prog = link->prog; char prog_tag[sizeof(prog->tag) * 2 + 1] = { }; - bin2hex(prog_tag, prog->tag, sizeof(prog->tag)); seq_printf(m, "link_type:\t%s\n" - "link_id:\t%u\n" - "prog_tag:\t%s\n" - "prog_id:\t%u\n", + "link_id:\t%u\n", bpf_link_type_strs[link->type], - link->id, - prog_tag, - prog->aux->id); + link->id); + if (prog) { + bin2hex(prog_tag, prog->tag, sizeof(prog->tag)); + seq_printf(m, + "prog_tag:\t%s\n" + "prog_id:\t%u\n", + prog_tag, + prog->aux->id); + } if (link->ops->show_fdinfo) link->ops->show_fdinfo(link, m); } @@ -4278,7 +4282,8 @@ static int bpf_link_get_info_by_fd(struct file *file, info.type = link->type; info.id = link->id; - info.prog_id = link->prog->aux->id; + if (link->prog) + info.prog_id = link->prog->aux->id; if (link->ops->fill_link_info) { err = link->ops->fill_link_info(link, &info); @@ -4541,6 +4546,9 @@ static int link_create(union bpf_attr *attr, bpfptr_t uattr) if (CHECK_ATTR(BPF_LINK_CREATE)) return -EINVAL; + if (attr->link_create.attach_type == BPF_STRUCT_OPS) + return bpf_struct_ops_link_create(attr); + prog = bpf_prog_get(attr->link_create.prog_fd); if (IS_ERR(prog)) return PTR_ERR(prog); diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 17afd2b35ee5..cd0ff39981e8 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -1033,6 +1033,7 @@ enum bpf_attach_type { BPF_PERF_EVENT, BPF_TRACE_KPROBE_MULTI, BPF_LSM_CGROUP, + BPF_STRUCT_OPS, __MAX_BPF_ATTACH_TYPE }; @@ -1266,6 +1267,9 @@ enum { /* Create a map that is suitable to be an inner map with dynamic max entries */ BPF_F_INNER_MAP = (1U << 12), + +/* Create a map that will be registered/unregesitered by the backed bpf_link */ + BPF_F_LINK = (1U << 13), }; /* Flags for BPF_PROG_QUERY. */ @@ -1507,7 +1511,10 @@ union bpf_attr { } task_fd_query; struct { /* struct used by BPF_LINK_CREATE command */ - __u32 prog_fd; /* eBPF program to attach */ + union { + __u32 prog_fd; /* eBPF program to attach */ + __u32 map_fd; /* eBPF struct_ops to attach */ + }; union { __u32 target_fd; /* object to attach to */ __u32 target_ifindex; /* target ifindex */ @@ -6354,6 +6361,9 @@ struct bpf_link_info { struct { __u32 ifindex; } xdp; + struct { + __u32 map_id; + } struct_ops; }; } __attribute__((aligned(8)));