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[75.172.126.232]) by smtp.gmail.com with ESMTPSA id c9-20020a637249000000b00502f20aa4desm7589490pgn.70.2023.03.01.07.51.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 Mar 2023 07:51:09 -0800 (PST) From: Joanne Koong To: bpf@vger.kernel.org Cc: martin.lau@kernel.org, andrii@kernel.org, ast@kernel.org, memxor@gmail.com, daniel@iogearbox.net, netdev@vger.kernel.org, toke@kernel.org, Joanne Koong Subject: [PATCH v13 bpf-next 08/10] bpf: Add xdp dynptrs Date: Wed, 1 Mar 2023 07:49:51 -0800 Message-Id: <20230301154953.641654-9-joannelkoong@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230301154953.641654-1-joannelkoong@gmail.com> References: <20230301154953.641654-1-joannelkoong@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Add xdp dynptrs, which are dynptrs whose underlying pointer points to a xdp_buff. The dynptr acts on xdp data. xdp dynptrs have two main benefits. One is that they allow operations on sizes that are not statically known at compile-time (eg variable-sized accesses). Another is that parsing the packet data through dynptrs (instead of through direct access of xdp->data and xdp->data_end) can be more ergonomic and less brittle (eg does not need manual if checking for being within bounds of data_end). For reads and writes on the dynptr, this includes reading/writing from/to and across fragments. Data slices through the bpf_dynptr_data API are not supported; instead bpf_dynptr_slice() and bpf_dynptr_slice_rdwr() should be used. For examples of how xdp dynptrs can be used, please see the attached selftests. Signed-off-by: Joanne Koong --- include/linux/bpf.h | 8 +++++++- include/linux/filter.h | 14 +++++++++++++ include/uapi/linux/bpf.h | 2 +- kernel/bpf/helpers.c | 9 ++++++++- kernel/bpf/verifier.c | 10 +++++++++ net/core/filter.c | 37 ++++++++++++++++++++++++++++++++-- tools/include/uapi/linux/bpf.h | 2 +- 7 files changed, 76 insertions(+), 6 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index e7436d7615b0..23ec684e660d 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -610,11 +610,15 @@ enum bpf_type_flag { /* DYNPTR points to sk_buff */ DYNPTR_TYPE_SKB = BIT(15 + BPF_BASE_TYPE_BITS), + /* DYNPTR points to xdp_buff */ + DYNPTR_TYPE_XDP = BIT(16 + BPF_BASE_TYPE_BITS), + __BPF_TYPE_FLAG_MAX, __BPF_TYPE_LAST_FLAG = __BPF_TYPE_FLAG_MAX - 1, }; -#define DYNPTR_TYPE_FLAG_MASK (DYNPTR_TYPE_LOCAL | DYNPTR_TYPE_RINGBUF | DYNPTR_TYPE_SKB) +#define DYNPTR_TYPE_FLAG_MASK (DYNPTR_TYPE_LOCAL | DYNPTR_TYPE_RINGBUF | DYNPTR_TYPE_SKB \ + | DYNPTR_TYPE_XDP) /* Max number of base types. */ #define BPF_BASE_TYPE_LIMIT (1UL << BPF_BASE_TYPE_BITS) @@ -1151,6 +1155,8 @@ enum bpf_dynptr_type { BPF_DYNPTR_TYPE_RINGBUF, /* Underlying data is a sk_buff */ BPF_DYNPTR_TYPE_SKB, + /* Underlying data is a xdp_buff */ + BPF_DYNPTR_TYPE_XDP, }; int bpf_dynptr_check_size(u32 size); diff --git a/include/linux/filter.h b/include/linux/filter.h index de18e844d15e..3f6992261ec5 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -1546,6 +1546,8 @@ static __always_inline int __bpf_xdp_redirect_map(struct bpf_map *map, u64 index int __bpf_skb_load_bytes(const struct sk_buff *skb, u32 offset, void *to, u32 len); int __bpf_skb_store_bytes(struct sk_buff *skb, u32 offset, const void *from, u32 len, u64 flags); +int __bpf_xdp_load_bytes(struct xdp_buff *xdp, u32 offset, void *buf, u32 len); +int __bpf_xdp_store_bytes(struct xdp_buff *xdp, u32 offset, void *buf, u32 len); #else /* CONFIG_NET */ static inline int __bpf_skb_load_bytes(const struct sk_buff *skb, u32 offset, void *to, u32 len) @@ -1558,6 +1560,18 @@ static inline int __bpf_skb_store_bytes(struct sk_buff *skb, u32 offset, { return -EOPNOTSUPP; } + +static inline int __bpf_xdp_load_bytes(struct xdp_buff *xdp, u32 offset, + void *buf, u32 len) +{ + return -EOPNOTSUPP; +} + +static inline int __bpf_xdp_store_bytes(struct xdp_buff *xdp, u32 offset, + void *buf, u32 len) +{ + return -EOPNOTSUPP; +} #endif /* CONFIG_NET */ #endif /* __LINUX_FILTER_H__ */ diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index d0351d30e551..faa304c926cf 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -5344,7 +5344,7 @@ union bpf_attr { * *len* must be a statically known value. The returned data slice * is invalidated whenever the dynptr is invalidated. * - * skb type dynptrs may not use bpf_dynptr_data. They should + * skb and xdp type dynptrs may not use bpf_dynptr_data. They should * instead use bpf_dynptr_slice and bpf_dynptr_slice_rdwr. * Return * Pointer to the underlying dynptr data, NULL if the dynptr is diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index e8e2414d1587..114a875a05b1 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -1530,6 +1530,8 @@ BPF_CALL_5(bpf_dynptr_read, void *, dst, u32, len, const struct bpf_dynptr_kern return 0; case BPF_DYNPTR_TYPE_SKB: return __bpf_skb_load_bytes(src->data, src->offset + offset, dst, len); + case BPF_DYNPTR_TYPE_XDP: + return __bpf_xdp_load_bytes(src->data, src->offset + offset, dst, len); default: WARN_ONCE(true, "bpf_dynptr_read: unknown dynptr type %d\n", type); return -EFAULT; @@ -1576,6 +1578,10 @@ BPF_CALL_5(bpf_dynptr_write, const struct bpf_dynptr_kern *, dst, u32, offset, v case BPF_DYNPTR_TYPE_SKB: return __bpf_skb_store_bytes(dst->data, dst->offset + offset, src, len, flags); + case BPF_DYNPTR_TYPE_XDP: + if (flags) + return -EINVAL; + return __bpf_xdp_store_bytes(dst->data, dst->offset + offset, src, len); default: WARN_ONCE(true, "bpf_dynptr_write: unknown dynptr type %d\n", type); return -EFAULT; @@ -1615,7 +1621,8 @@ BPF_CALL_3(bpf_dynptr_data, const struct bpf_dynptr_kern *, ptr, u32, offset, u3 case BPF_DYNPTR_TYPE_RINGBUF: return (unsigned long)(ptr->data + ptr->offset + offset); case BPF_DYNPTR_TYPE_SKB: - /* skb dynptrs should use bpf_dynptr_slice / bpf_dynptr_slice_rdwr */ + case BPF_DYNPTR_TYPE_XDP: + /* skb and xdp dynptrs should use bpf_dynptr_slice / bpf_dynptr_slice_rdwr */ return 0; default: WARN_ONCE(true, "bpf_dynptr_data: unknown dynptr type %d\n", type); diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 4f5fce16543b..5e42946e53ab 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -752,6 +752,8 @@ static enum bpf_dynptr_type arg_to_dynptr_type(enum bpf_arg_type arg_type) return BPF_DYNPTR_TYPE_RINGBUF; case DYNPTR_TYPE_SKB: return BPF_DYNPTR_TYPE_SKB; + case DYNPTR_TYPE_XDP: + return BPF_DYNPTR_TYPE_XDP; default: return BPF_DYNPTR_TYPE_INVALID; } @@ -6300,6 +6302,9 @@ static int process_dynptr_func(struct bpf_verifier_env *env, int regno, int insn case DYNPTR_TYPE_SKB: err_extra = "skb "; break; + case DYNPTR_TYPE_XDP: + err_extra = "xdp "; + break; default: err_extra = ""; break; @@ -8943,6 +8948,7 @@ enum special_kfunc_type { KF_bpf_rbtree_add, KF_bpf_rbtree_first, KF_bpf_dynptr_from_skb, + KF_bpf_dynptr_from_xdp, }; BTF_SET_START(special_kfunc_set) @@ -8958,6 +8964,7 @@ BTF_ID(func, bpf_rbtree_remove) BTF_ID(func, bpf_rbtree_add) BTF_ID(func, bpf_rbtree_first) BTF_ID(func, bpf_dynptr_from_skb) +BTF_ID(func, bpf_dynptr_from_xdp) BTF_SET_END(special_kfunc_set) BTF_ID_LIST(special_kfunc_list) @@ -8975,6 +8982,7 @@ BTF_ID(func, bpf_rbtree_remove) BTF_ID(func, bpf_rbtree_add) BTF_ID(func, bpf_rbtree_first) BTF_ID(func, bpf_dynptr_from_skb) +BTF_ID(func, bpf_dynptr_from_xdp) static bool is_kfunc_bpf_rcu_read_lock(struct bpf_kfunc_call_arg_meta *meta) { @@ -9731,6 +9739,8 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_ if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_from_skb]) dynptr_arg_type |= DYNPTR_TYPE_SKB; + else if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_from_xdp]) + dynptr_arg_type |= DYNPTR_TYPE_XDP; ret = process_dynptr_func(env, regno, insn_idx, dynptr_arg_type); if (ret < 0) diff --git a/net/core/filter.c b/net/core/filter.c index f3afa31a9b10..c692046fa7f6 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -3839,7 +3839,7 @@ static const struct bpf_func_proto sk_skb_change_head_proto = { .arg3_type = ARG_ANYTHING, }; -BPF_CALL_1(bpf_xdp_get_buff_len, struct xdp_buff*, xdp) +BPF_CALL_1(bpf_xdp_get_buff_len, struct xdp_buff*, xdp) { return xdp_get_buff_len(xdp); } @@ -3999,6 +3999,11 @@ static const struct bpf_func_proto bpf_xdp_load_bytes_proto = { .arg4_type = ARG_CONST_SIZE, }; +int __bpf_xdp_load_bytes(struct xdp_buff *xdp, u32 offset, void *buf, u32 len) +{ + return ____bpf_xdp_load_bytes(xdp, offset, buf, len); +} + BPF_CALL_4(bpf_xdp_store_bytes, struct xdp_buff *, xdp, u32, offset, void *, buf, u32, len) { @@ -4026,6 +4031,11 @@ static const struct bpf_func_proto bpf_xdp_store_bytes_proto = { .arg4_type = ARG_CONST_SIZE, }; +int __bpf_xdp_store_bytes(struct xdp_buff *xdp, u32 offset, void *buf, u32 len) +{ + return ____bpf_xdp_store_bytes(xdp, offset, buf, len); +} + static int bpf_xdp_frags_increase_tail(struct xdp_buff *xdp, int offset) { struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp); @@ -11648,6 +11658,19 @@ __bpf_kfunc int bpf_dynptr_from_skb(struct sk_buff *skb, u64 flags, return 0; } + +__bpf_kfunc int bpf_dynptr_from_xdp(struct xdp_buff *xdp, u64 flags, + struct bpf_dynptr_kern *ptr__uninit) +{ + if (flags) { + bpf_dynptr_set_null(ptr__uninit); + return -EINVAL; + } + + bpf_dynptr_init(ptr__uninit, xdp, BPF_DYNPTR_TYPE_XDP, 0, xdp_get_buff_len(xdp)); + + return 0; +} __diag_pop(); int bpf_dynptr_from_skb_rdonly(struct sk_buff *skb, u64 flags, @@ -11668,11 +11691,20 @@ BTF_SET8_START(bpf_kfunc_check_set_skb) BTF_ID_FLAGS(func, bpf_dynptr_from_skb) BTF_SET8_END(bpf_kfunc_check_set_skb) +BTF_SET8_START(bpf_kfunc_check_set_xdp) +BTF_ID_FLAGS(func, bpf_dynptr_from_xdp) +BTF_SET8_END(bpf_kfunc_check_set_xdp) + static const struct btf_kfunc_id_set bpf_kfunc_set_skb = { .owner = THIS_MODULE, .set = &bpf_kfunc_check_set_skb, }; +static const struct btf_kfunc_id_set bpf_kfunc_set_xdp = { + .owner = THIS_MODULE, + .set = &bpf_kfunc_check_set_xdp, +}; + static int __init bpf_kfunc_init(void) { int ret; @@ -11685,6 +11717,7 @@ static int __init bpf_kfunc_init(void) ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_LWT_OUT, &bpf_kfunc_set_skb); ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_LWT_IN, &bpf_kfunc_set_skb); ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_LWT_XMIT, &bpf_kfunc_set_skb); - return ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_LWT_SEG6LOCAL, &bpf_kfunc_set_skb); + ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_LWT_SEG6LOCAL, &bpf_kfunc_set_skb); + return ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &bpf_kfunc_set_xdp); } late_initcall(bpf_kfunc_init); diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index d0351d30e551..faa304c926cf 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -5344,7 +5344,7 @@ union bpf_attr { * *len* must be a statically known value. The returned data slice * is invalidated whenever the dynptr is invalidated. * - * skb type dynptrs may not use bpf_dynptr_data. They should + * skb and xdp type dynptrs may not use bpf_dynptr_data. They should * instead use bpf_dynptr_slice and bpf_dynptr_slice_rdwr. * Return * Pointer to the underlying dynptr data, NULL if the dynptr is