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Miller" , Jakub Kicinski , Petar Penkov , Lorenz Bauer , Eric Dumazet , Hideaki YOSHIFUJI , "David Ahern" , Shuah Khan , "Jesper Dangaard Brouer" , Nathan Chancellor , "Nick Desaulniers" , Joe Stringer , "Florent Revest" , , =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , "Kumar Kartikeya Dwivedi" , Florian Westphal , "Maxim Mikityanskiy" Subject: [PATCH bpf-next v2 1/3] bpf: Make errors of bpf_tcp_check_syncookie distinguishable Date: Mon, 24 Jan 2022 17:13:38 +0200 Message-ID: <20220124151340.376807-2-maximmi@nvidia.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220124151340.376807-1-maximmi@nvidia.com> References: <20220124151340.376807-1-maximmi@nvidia.com> MIME-Version: 1.0 X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: c3c499b7-0aaf-4a66-685d-08d9df4c2460 X-MS-TrafficTypeDiagnostic: MN2PR12MB4221:EE_ X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:10000; X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:12.22.5.234;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:mail.nvidia.com;PTR:InfoNoRecords;CAT:NONE;SFS:(4636009)(40470700004)(36840700001)(46966006)(86362001)(2616005)(40460700003)(336012)(8676002)(6666004)(70206006)(186003)(70586007)(7416002)(47076005)(8936002)(107886003)(82310400004)(2906002)(356005)(426003)(81166007)(83380400001)(1076003)(7696005)(508600001)(4326008)(26005)(36860700001)(36756003)(54906003)(5660300002)(110136005)(316002)(36900700001);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Jan 2022 15:13:56.8723 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: c3c499b7-0aaf-4a66-685d-08d9df4c2460 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[12.22.5.234];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BN8NAM11FT042.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB4221 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org bpf_tcp_check_syncookie returns ambiguous error codes in some cases. The list below shows various error conditions and matching error codes: 1. NULL socket: -EINVAL. 2. Invalid packet: -EINVAL, -ENOENT. 3. Bad cookie: -ENOENT. 4. Cookies are not in use: -EINVAL, -ENOENT. 5. Good cookie: 0. As we see, the same error code may correspond to multiple error conditions, making them undistinguishable, and at the same time one error condition may return different codes, although it's typically handled in the same way. This patch reassigns error codes of bpf_tcp_check_syncookie and documents them: 1. Invalid packet or NULL socket: -EINVAL; 2. Bad cookie: -EACCES. 3. Cookies are not in use: -ENOENT. 4. Good cookie: 0. This change allows XDP programs to make smarter decisions based on error code, because different error conditions are now easily distinguishable. Backward compatibility shouldn't suffer because of these reasons: 1. The specific error codes weren't documented. The behavior that used to be documented (0 is good cookie, negative values are errors) still holds. Anyone who relied on implementation details should have understood the risks. 2. Two known usecases (classification of ACKs with cookies that initial new connections, SYN flood protection) take decisions which don't depend on specific error codes: Traffic classification: ACK packet is new, error == 0: classify as NEW. ACK packet is new, error < 0: classify as INVALID. SYN flood protection: ACK packet is new, error == 0: good cookie, XDP_PASS. ACK packet is new, error < 0: bad cookie, XDP_DROP. As Lorenz Bauer confirms, their implementation of traffic classifier won't break, as well as the kernel selftests. 3. It's hard to imagine that old error codes could be used for any useful decisions. Signed-off-by: Maxim Mikityanskiy Reviewed-by: Tariq Toukan --- include/uapi/linux/bpf.h | 18 ++++++++++++++++-- net/core/filter.c | 6 +++--- tools/include/uapi/linux/bpf.h | 18 ++++++++++++++++-- 3 files changed, 35 insertions(+), 7 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 16a7574292a5..4d2d4a09bf25 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -3575,8 +3575,22 @@ union bpf_attr { * *th* points to the start of the TCP header, while *th_len* * contains **sizeof**\ (**struct tcphdr**). * Return - * 0 if *iph* and *th* are a valid SYN cookie ACK, or a negative - * error otherwise. + * 0 if *iph* and *th* are a valid SYN cookie ACK. + * + * On failure, the returned value is one of the following: + * + * **-EACCES** if the SYN cookie is not valid. + * + * **-EINVAL** if the packet or input arguments are invalid. + * + * **-ENOENT** if SYN cookies are not issued (no SYN flood, or SYN + * cookies are disabled in sysctl). + * + * **-EOPNOTSUPP** if the kernel configuration does not enable SYN + * cookies (CONFIG_SYN_COOKIES is off). + * + * **-EPROTONOSUPPORT** if the IP version is not 4 or 6 (or 6, but + * CONFIG_IPV6 is disabled). * * long bpf_sysctl_get_name(struct bpf_sysctl *ctx, char *buf, size_t buf_len, u64 flags) * Description diff --git a/net/core/filter.c b/net/core/filter.c index a06931c27eeb..18559b5828a3 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -6998,10 +6998,10 @@ BPF_CALL_5(bpf_tcp_check_syncookie, struct sock *, sk, void *, iph, u32, iph_len return -EINVAL; if (!sock_net(sk)->ipv4.sysctl_tcp_syncookies) - return -EINVAL; + return -ENOENT; if (!th->ack || th->rst || th->syn) - return -ENOENT; + return -EINVAL; if (tcp_synq_no_recent_overflow(sk)) return -ENOENT; @@ -7032,7 +7032,7 @@ BPF_CALL_5(bpf_tcp_check_syncookie, struct sock *, sk, void *, iph, u32, iph_len if (ret > 0) return 0; - return -ENOENT; + return -EACCES; #else return -ENOTSUPP; #endif diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 16a7574292a5..4d2d4a09bf25 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -3575,8 +3575,22 @@ union bpf_attr { * *th* points to the start of the TCP header, while *th_len* * contains **sizeof**\ (**struct tcphdr**). * Return - * 0 if *iph* and *th* are a valid SYN cookie ACK, or a negative - * error otherwise. + * 0 if *iph* and *th* are a valid SYN cookie ACK. + * + * On failure, the returned value is one of the following: + * + * **-EACCES** if the SYN cookie is not valid. + * + * **-EINVAL** if the packet or input arguments are invalid. + * + * **-ENOENT** if SYN cookies are not issued (no SYN flood, or SYN + * cookies are disabled in sysctl). + * + * **-EOPNOTSUPP** if the kernel configuration does not enable SYN + * cookies (CONFIG_SYN_COOKIES is off). + * + * **-EPROTONOSUPPORT** if the IP version is not 4 or 6 (or 6, but + * CONFIG_IPV6 is disabled). * * long bpf_sysctl_get_name(struct bpf_sysctl *ctx, char *buf, size_t buf_len, u64 flags) * Description From patchwork Mon Jan 24 15:13:39 2022 Content-Type: text/plain; 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Mon, 24 Jan 2022 07:13:56 -0800 From: Maxim Mikityanskiy To: , Alexei Starovoitov , "Daniel Borkmann" , Andrii Nakryiko , CC: Tariq Toukan , Martin KaFai Lau , "Song Liu" , Yonghong Song , John Fastabend , KP Singh , "David S. Miller" , Jakub Kicinski , Petar Penkov , Lorenz Bauer , Eric Dumazet , Hideaki YOSHIFUJI , "David Ahern" , Shuah Khan , "Jesper Dangaard Brouer" , Nathan Chancellor , "Nick Desaulniers" , Joe Stringer , "Florent Revest" , , =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , "Kumar Kartikeya Dwivedi" , Florian Westphal , "Maxim Mikityanskiy" Subject: [PATCH bpf-next v2 2/3] bpf: Add helpers to issue and check SYN cookies in XDP Date: Mon, 24 Jan 2022 17:13:39 +0200 Message-ID: <20220124151340.376807-3-maximmi@nvidia.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220124151340.376807-1-maximmi@nvidia.com> References: <20220124151340.376807-1-maximmi@nvidia.com> MIME-Version: 1.0 X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 27be4611-373f-45d5-fe6c-08d9df4c2870 X-MS-TrafficTypeDiagnostic: DM5PR1201MB0042:EE_ X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:10000; X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:12.22.5.236;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:mail.nvidia.com;PTR:InfoNoRecords;CAT:NONE;SFS:(4636009)(46966006)(36840700001)(40470700004)(1076003)(30864003)(110136005)(186003)(7696005)(82310400004)(4326008)(83380400001)(426003)(5660300002)(36756003)(356005)(86362001)(2906002)(508600001)(7416002)(316002)(2616005)(54906003)(81166007)(8936002)(47076005)(70206006)(6666004)(107886003)(70586007)(40460700003)(26005)(8676002)(336012)(36860700001)(36900700001);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Jan 2022 15:14:03.6294 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 27be4611-373f-45d5-fe6c-08d9df4c2870 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[12.22.5.236];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BN8NAM11FT057.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR1201MB0042 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org The new helpers bpf_tcp_raw_{gen,check}_syncookie allow an XDP program to generate SYN cookies in response to TCP SYN packets and to check those cookies upon receiving the first ACK packet (the final packet of the TCP handshake). Unlike bpf_tcp_{gen,check}_syncookie these new helpers don't need a listening socket on the local machine, which allows to use them together with synproxy to accelerate SYN cookie generation. Signed-off-by: Maxim Mikityanskiy Reviewed-by: Tariq Toukan --- include/net/tcp.h | 1 + include/uapi/linux/bpf.h | 57 +++++++++++++++ net/core/filter.c | 122 +++++++++++++++++++++++++++++++++ net/ipv4/tcp_input.c | 3 +- tools/include/uapi/linux/bpf.h | 57 +++++++++++++++ 5 files changed, 239 insertions(+), 1 deletion(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 44e442bf23f9..0aca79f7b1be 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -432,6 +432,7 @@ u16 tcp_v4_get_syncookie(struct sock *sk, struct iphdr *iph, struct tcphdr *th, u32 *cookie); u16 tcp_v6_get_syncookie(struct sock *sk, struct ipv6hdr *iph, struct tcphdr *th, u32 *cookie); +u16 tcp_parse_mss_option(const struct tcphdr *th, u16 user_mss); u16 tcp_get_syncookie_mss(struct request_sock_ops *rsk_ops, const struct tcp_request_sock_ops *af_ops, struct sock *sk, struct tcphdr *th); diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 4d2d4a09bf25..07864277297b 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -5090,6 +5090,61 @@ union bpf_attr { * associated to *xdp_md*, at *offset*. * Return * 0 on success, or a negative error in case of failure. + * + * s64 bpf_tcp_raw_gen_syncookie(void *iph, u32 iph_len, struct tcphdr *th, u32 th_len) + * Description + * Try to issue a SYN cookie for the packet with corresponding + * IP/TCP headers, *iph* and *th*, without depending on a listening + * socket. + * + * *iph* points to the start of the IPv4 or IPv6 header, while + * *iph_len* contains **sizeof**\ (**struct iphdr**) or + * **sizeof**\ (**struct ip6hdr**). + * + * *th* points to the start of the TCP header, while *th_len* + * contains the length of the TCP header (at least + * **sizeof**\ (**struct tcphdr**)). + * Return + * On success, lower 32 bits hold the generated SYN cookie in + * followed by 16 bits which hold the MSS value for that cookie, + * and the top 16 bits are unused. + * + * On failure, the returned value is one of the following: + * + * **-EINVAL** if the packet or input arguments are invalid. + * + * **-EOPNOTSUPP** if the kernel configuration does not enable SYN + * cookies (CONFIG_SYN_COOKIES is off). + * + * **-EPROTONOSUPPORT** if the IP version is not 4 or 6 (or 6, but + * CONFIG_IPV6 is disabled). + * + * int bpf_tcp_raw_check_syncookie(void *iph, u32 iph_len, struct tcphdr *th, u32 th_len) + * Description + * Check whether *iph* and *th* contain a valid SYN cookie ACK + * without depending on a listening socket. + * + * *iph* points to the start of the IPv4 or IPv6 header, while + * *iph_len* contains **sizeof**\ (**struct iphdr**) or + * **sizeof**\ (**struct ip6hdr**). + * + * *th* points to the start of the TCP header, while *th_len* + * contains the length of the TCP header (at least + * **sizeof**\ (**struct tcphdr**)). + * Return + * 0 if *iph* and *th* are a valid SYN cookie ACK. + * + * On failure, the returned value is one of the following: + * + * **-EACCES** if the SYN cookie is not valid. + * + * **-EINVAL** if the packet or input arguments are invalid. + * + * **-EOPNOTSUPP** if the kernel configuration does not enable SYN + * cookies (CONFIG_SYN_COOKIES is off). + * + * **-EPROTONOSUPPORT** if the IP version is not 4 or 6 (or 6, but + * CONFIG_IPV6 is disabled). */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -5283,6 +5338,8 @@ union bpf_attr { FN(xdp_get_buff_len), \ FN(xdp_load_bytes), \ FN(xdp_store_bytes), \ + FN(tcp_raw_gen_syncookie), \ + FN(tcp_raw_check_syncookie), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper diff --git a/net/core/filter.c b/net/core/filter.c index 18559b5828a3..dc90d2649a7a 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -7375,6 +7375,124 @@ static const struct bpf_func_proto bpf_sock_ops_reserve_hdr_opt_proto = { .arg3_type = ARG_ANYTHING, }; +BPF_CALL_4(bpf_tcp_raw_gen_syncookie, void *, iph, u32, iph_len, + struct tcphdr *, th, u32, th_len) +{ +#ifdef CONFIG_SYN_COOKIES + u32 cookie; + u16 mss; + + if (unlikely(th_len < sizeof(*th) || th_len != th->doff * 4)) + return -EINVAL; + + if (!th->syn || th->ack || th->fin || th->rst) + return -EINVAL; + + if (unlikely(iph_len < sizeof(struct iphdr))) + return -EINVAL; + + /* Both struct iphdr and struct ipv6hdr have the version field at the + * same offset so we can cast to the shorter header (struct iphdr). + */ + switch (((struct iphdr *)iph)->version) { + case 4: + mss = tcp_parse_mss_option(th, 0) ?: TCP_MSS_DEFAULT; + cookie = __cookie_v4_init_sequence(iph, th, &mss); + break; + +#if IS_BUILTIN(CONFIG_IPV6) + case 6: { + const u16 mss_clamp = IPV6_MIN_MTU - sizeof(struct tcphdr) - sizeof(struct ipv6hdr); + + if (unlikely(iph_len < sizeof(struct ipv6hdr))) + return -EINVAL; + + mss = tcp_parse_mss_option(th, 0) ?: mss_clamp; + cookie = __cookie_v6_init_sequence(iph, th, &mss); + break; + } +#endif /* CONFIG_IPV6 */ + + default: + return -EPROTONOSUPPORT; + } + + return cookie | ((u64)mss << 32); +#else + return -EOPNOTSUPP; +#endif /* CONFIG_SYN_COOKIES */ +} + +static const struct bpf_func_proto bpf_tcp_raw_gen_syncookie_proto = { + .func = bpf_tcp_raw_gen_syncookie, + .gpl_only = true, /* __cookie_v*_init_sequence() is GPL */ + .pkt_access = true, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_MEM, + .arg2_type = ARG_CONST_SIZE, + .arg3_type = ARG_PTR_TO_MEM, + .arg4_type = ARG_CONST_SIZE, +}; + +BPF_CALL_4(bpf_tcp_raw_check_syncookie, void *, iph, u32, iph_len, + struct tcphdr *, th, u32, th_len) +{ +#ifdef CONFIG_SYN_COOKIES + u32 cookie; + int ret; + + if (unlikely(th_len < sizeof(*th))) + return -EINVAL; + + if (!th->ack || th->rst || th->syn) + return -EINVAL; + + if (unlikely(iph_len < sizeof(struct iphdr))) + return -EINVAL; + + cookie = ntohl(th->ack_seq) - 1; + + /* Both struct iphdr and struct ipv6hdr have the version field at the + * same offset so we can cast to the shorter header (struct iphdr). + */ + switch (((struct iphdr *)iph)->version) { + case 4: + ret = __cookie_v4_check((struct iphdr *)iph, th, cookie); + break; + +#if IS_BUILTIN(CONFIG_IPV6) + case 6: + if (unlikely(iph_len < sizeof(struct ipv6hdr))) + return -EINVAL; + + ret = __cookie_v6_check((struct ipv6hdr *)iph, th, cookie); + break; +#endif /* CONFIG_IPV6 */ + + default: + return -EPROTONOSUPPORT; + } + + if (ret > 0) + return 0; + + return -EACCES; +#else + return -EOPNOTSUPP; +#endif +} + +static const struct bpf_func_proto bpf_tcp_raw_check_syncookie_proto = { + .func = bpf_tcp_raw_check_syncookie, + .gpl_only = true, /* __cookie_v*_check is GPL */ + .pkt_access = true, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_MEM, + .arg2_type = ARG_CONST_SIZE, + .arg3_type = ARG_PTR_TO_MEM, + .arg4_type = ARG_CONST_SIZE, +}; + #endif /* CONFIG_INET */ bool bpf_helper_changes_pkt_data(void *func) @@ -7785,6 +7903,10 @@ xdp_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_tcp_check_syncookie_proto; case BPF_FUNC_tcp_gen_syncookie: return &bpf_tcp_gen_syncookie_proto; + case BPF_FUNC_tcp_raw_gen_syncookie: + return &bpf_tcp_raw_gen_syncookie_proto; + case BPF_FUNC_tcp_raw_check_syncookie: + return &bpf_tcp_raw_check_syncookie_proto; #endif default: return bpf_sk_base_func_proto(func_id); diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index dc49a3d551eb..a60f6aa44b02 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3961,7 +3961,7 @@ static bool smc_parse_options(const struct tcphdr *th, /* Try to parse the MSS option from the TCP header. Return 0 on failure, clamped * value on success. */ -static u16 tcp_parse_mss_option(const struct tcphdr *th, u16 user_mss) +u16 tcp_parse_mss_option(const struct tcphdr *th, u16 user_mss) { const unsigned char *ptr = (const unsigned char *)(th + 1); int length = (th->doff * 4) - sizeof(struct tcphdr); @@ -4000,6 +4000,7 @@ static u16 tcp_parse_mss_option(const struct tcphdr *th, u16 user_mss) } return mss; } +EXPORT_SYMBOL_GPL(tcp_parse_mss_option); /* Look for tcp options. Normally only called on SYN and SYNACK packets. * But, this can also be called on packets in the established flow when diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 4d2d4a09bf25..07864277297b 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -5090,6 +5090,61 @@ union bpf_attr { * associated to *xdp_md*, at *offset*. * Return * 0 on success, or a negative error in case of failure. + * + * s64 bpf_tcp_raw_gen_syncookie(void *iph, u32 iph_len, struct tcphdr *th, u32 th_len) + * Description + * Try to issue a SYN cookie for the packet with corresponding + * IP/TCP headers, *iph* and *th*, without depending on a listening + * socket. + * + * *iph* points to the start of the IPv4 or IPv6 header, while + * *iph_len* contains **sizeof**\ (**struct iphdr**) or + * **sizeof**\ (**struct ip6hdr**). + * + * *th* points to the start of the TCP header, while *th_len* + * contains the length of the TCP header (at least + * **sizeof**\ (**struct tcphdr**)). + * Return + * On success, lower 32 bits hold the generated SYN cookie in + * followed by 16 bits which hold the MSS value for that cookie, + * and the top 16 bits are unused. + * + * On failure, the returned value is one of the following: + * + * **-EINVAL** if the packet or input arguments are invalid. + * + * **-EOPNOTSUPP** if the kernel configuration does not enable SYN + * cookies (CONFIG_SYN_COOKIES is off). + * + * **-EPROTONOSUPPORT** if the IP version is not 4 or 6 (or 6, but + * CONFIG_IPV6 is disabled). + * + * int bpf_tcp_raw_check_syncookie(void *iph, u32 iph_len, struct tcphdr *th, u32 th_len) + * Description + * Check whether *iph* and *th* contain a valid SYN cookie ACK + * without depending on a listening socket. + * + * *iph* points to the start of the IPv4 or IPv6 header, while + * *iph_len* contains **sizeof**\ (**struct iphdr**) or + * **sizeof**\ (**struct ip6hdr**). + * + * *th* points to the start of the TCP header, while *th_len* + * contains the length of the TCP header (at least + * **sizeof**\ (**struct tcphdr**)). + * Return + * 0 if *iph* and *th* are a valid SYN cookie ACK. + * + * On failure, the returned value is one of the following: + * + * **-EACCES** if the SYN cookie is not valid. + * + * **-EINVAL** if the packet or input arguments are invalid. + * + * **-EOPNOTSUPP** if the kernel configuration does not enable SYN + * cookies (CONFIG_SYN_COOKIES is off). + * + * **-EPROTONOSUPPORT** if the IP version is not 4 or 6 (or 6, but + * CONFIG_IPV6 is disabled). */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -5283,6 +5338,8 @@ union bpf_attr { FN(xdp_get_buff_len), \ FN(xdp_load_bytes), \ FN(xdp_store_bytes), \ + FN(tcp_raw_gen_syncookie), \ + FN(tcp_raw_check_syncookie), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper From patchwork Mon Jan 24 15:13:40 2022 Content-Type: text/plain; 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Mon, 24 Jan 2022 07:14:03 -0800 From: Maxim Mikityanskiy To: , Alexei Starovoitov , "Daniel Borkmann" , Andrii Nakryiko , CC: Tariq Toukan , Martin KaFai Lau , "Song Liu" , Yonghong Song , John Fastabend , KP Singh , "David S. Miller" , Jakub Kicinski , Petar Penkov , Lorenz Bauer , Eric Dumazet , Hideaki YOSHIFUJI , "David Ahern" , Shuah Khan , "Jesper Dangaard Brouer" , Nathan Chancellor , "Nick Desaulniers" , Joe Stringer , "Florent Revest" , , =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , "Kumar Kartikeya Dwivedi" , Florian Westphal , "Maxim Mikityanskiy" Subject: [PATCH bpf-next v2 3/3] bpf: Add selftests for raw syncookie helpers Date: Mon, 24 Jan 2022 17:13:40 +0200 Message-ID: <20220124151340.376807-4-maximmi@nvidia.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220124151340.376807-1-maximmi@nvidia.com> References: <20220124151340.376807-1-maximmi@nvidia.com> MIME-Version: 1.0 X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 9a3237b2-b899-4187-dfac-08d9df4c2ca5 X-MS-TrafficTypeDiagnostic: BL1PR12MB5361:EE_ X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:150; X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:12.22.5.234;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:mail.nvidia.com;PTR:InfoNoRecords;CAT:NONE;SFS:(4636009)(46966006)(36840700001)(40470700004)(86362001)(5660300002)(30864003)(6666004)(336012)(2616005)(4326008)(426003)(508600001)(36860700001)(70586007)(107886003)(83380400001)(40460700003)(26005)(1076003)(186003)(82310400004)(70206006)(356005)(8676002)(7696005)(110136005)(54906003)(81166007)(2906002)(7416002)(47076005)(36756003)(316002)(8936002)(21314003)(36900700001);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Jan 2022 15:14:10.6712 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 9a3237b2-b899-4187-dfac-08d9df4c2ca5 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[12.22.5.234];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BN8NAM11FT047.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL1PR12MB5361 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org This commit adds selftests for the new BPF helpers: bpf_tcp_raw_gen_syncookie and bpf_tcp_raw_check_syncookie. xdp_synproxy_kern.c is a BPF program that generates SYN cookies on allowed TCP ports and sends SYNACKs to clients, accelerating synproxy iptables module. xdp_synproxy.c is a userspace control application that allows to configure the following options in runtime: list of allowed ports, MSS, window scale, TTL. test_xdp_synproxy.sh is a script that demonstrates the setup of synproxy with XDP acceleration and serves as a selftest for the new feature. Signed-off-by: Maxim Mikityanskiy Reviewed-by: Tariq Toukan --- tools/testing/selftests/bpf/.gitignore | 1 + tools/testing/selftests/bpf/Makefile | 5 +- .../selftests/bpf/progs/xdp_synproxy_kern.c | 743 ++++++++++++++++++ .../selftests/bpf/test_xdp_synproxy.sh | 71 ++ tools/testing/selftests/bpf/xdp_synproxy.c | 418 ++++++++++ 5 files changed, 1236 insertions(+), 2 deletions(-) create mode 100644 tools/testing/selftests/bpf/progs/xdp_synproxy_kern.c create mode 100755 tools/testing/selftests/bpf/test_xdp_synproxy.sh create mode 100644 tools/testing/selftests/bpf/xdp_synproxy.c diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore index 1dad8d617da8..1bcffd73632e 100644 --- a/tools/testing/selftests/bpf/.gitignore +++ b/tools/testing/selftests/bpf/.gitignore @@ -41,3 +41,4 @@ test_cpp *.tmp xdpxceiver xdp_redirect_multi +xdp_synproxy diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 945f92d71db3..8b9bcb2226da 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -72,7 +72,8 @@ TEST_PROGS := test_kmod.sh \ test_bpftool.sh \ test_bpftool_metadata.sh \ test_doc_build.sh \ - test_xsk.sh + test_xsk.sh \ + test_xdp_synproxy.sh TEST_PROGS_EXTENDED := with_addr.sh \ with_tunnels.sh \ @@ -82,7 +83,7 @@ TEST_PROGS_EXTENDED := with_addr.sh \ TEST_GEN_PROGS_EXTENDED = test_sock_addr test_skb_cgroup_id_user \ flow_dissector_load test_flow_dissector test_tcp_check_syncookie_user \ test_lirc_mode2_user xdping test_cpp runqslower bench bpf_testmod.ko \ - xdpxceiver xdp_redirect_multi + xdpxceiver xdp_redirect_multi xdp_synproxy TEST_CUSTOM_PROGS = $(OUTPUT)/urandom_read diff --git a/tools/testing/selftests/bpf/progs/xdp_synproxy_kern.c b/tools/testing/selftests/bpf/progs/xdp_synproxy_kern.c new file mode 100644 index 000000000000..a45d517e07ef --- /dev/null +++ b/tools/testing/selftests/bpf/progs/xdp_synproxy_kern.c @@ -0,0 +1,743 @@ +// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB +/* Copyright (c) 2021, NVIDIA CORPORATION & AFFILIATES. All rights reserved. */ + +#include "vmlinux.h" + +#include +#include +#include + +#define NSEC_PER_SEC 1000000000L + +#define ETH_ALEN 6 +#define ETH_P_IP 0x0800 +#define ETH_P_IPV6 0x86DD + +#define tcp_flag_word(tp) (((union tcp_word_hdr *)(tp))->words[3]) + +#define IP_DF 0x4000 +#define IP_MF 0x2000 +#define IP_OFFSET 0x1fff + +#define NEXTHDR_TCP 6 + +#define TCPOPT_NOP 1 +#define TCPOPT_EOL 0 +#define TCPOPT_MSS 2 +#define TCPOPT_WINDOW 3 +#define TCPOPT_SACK_PERM 4 +#define TCPOPT_TIMESTAMP 8 + +#define TCPOLEN_MSS 4 +#define TCPOLEN_WINDOW 3 +#define TCPOLEN_SACK_PERM 2 +#define TCPOLEN_TIMESTAMP 10 + +#define TCP_TS_HZ 1000 +#define TS_OPT_WSCALE_MASK 0xf +#define TS_OPT_SACK (1 << 4) +#define TS_OPT_ECN (1 << 5) +#define TSBITS 6 +#define TSMASK (((__u32)1 << TSBITS) - 1) +#define TCP_MAX_WSCALE 14U + +#define IPV4_MAXLEN 60 +#define TCP_MAXLEN 60 + +#define DEFAULT_MSS4 1460 +#define DEFAULT_MSS6 1440 +#define DEFAULT_WSCALE 7 +#define DEFAULT_TTL 64 +#define MAX_ALLOWED_PORTS 8 + +#define swap(a, b) \ + do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0) + +#define __get_unaligned_t(type, ptr) ({ \ + const struct { type x; } __attribute__((__packed__)) *__pptr = (typeof(__pptr))(ptr); \ + __pptr->x; \ +}) + +#define get_unaligned(ptr) __get_unaligned_t(typeof(*(ptr)), (ptr)) + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __type(key, __u32); + __type(value, __u64); + __uint(max_entries, 2); +} values SEC(".maps"); + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __type(key, __u32); + __type(value, __u16); + __uint(max_entries, MAX_ALLOWED_PORTS); +} allowed_ports SEC(".maps"); + +extern struct nf_conn *bpf_xdp_ct_lookup(struct xdp_md *xdp_ctx, + struct bpf_sock_tuple *bpf_tuple, + __u32 len_tuple, + struct bpf_ct_opts *opts, + __u32 len_opts) __ksym; + +extern void bpf_ct_release(struct nf_conn *ct) __ksym; + +static __always_inline void swap_eth_addr(__u8 *a, __u8 *b) +{ + __u8 tmp[ETH_ALEN]; + + __builtin_memcpy(tmp, a, ETH_ALEN); + __builtin_memcpy(a, b, ETH_ALEN); + __builtin_memcpy(b, tmp, ETH_ALEN); +} + +static __always_inline __u16 csum_fold(__u32 csum) +{ + csum = (csum & 0xffff) + (csum >> 16); + csum = (csum & 0xffff) + (csum >> 16); + return (__u16)~csum; +} + +static __always_inline __u16 csum_tcpudp_magic(__be32 saddr, __be32 daddr, + __u32 len, __u8 proto, + __u32 csum) +{ + __u64 s = csum; + + s += (__u32)saddr; + s += (__u32)daddr; +#if defined(__BIG_ENDIAN__) + s += proto + len; +#elif defined(__LITTLE_ENDIAN__) + s += (proto + len) << 8; +#else +#error Unknown endian +#endif + s = (s & 0xffffffff) + (s >> 32); + s = (s & 0xffffffff) + (s >> 32); + + return csum_fold((__u32)s); +} + +static __always_inline __u16 csum_ipv6_magic(const struct in6_addr *saddr, + const struct in6_addr *daddr, + __u32 len, __u8 proto, __u32 csum) +{ + __u64 sum = csum; + int i; + +#pragma unroll + for (i = 0; i < 4; i++) + sum += (__u32)saddr->in6_u.u6_addr32[i]; + +#pragma unroll + for (i = 0; i < 4; i++) + sum += (__u32)daddr->in6_u.u6_addr32[i]; + + // Don't combine additions to avoid 32-bit overflow. + sum += bpf_htonl(len); + sum += bpf_htonl(proto); + + sum = (sum & 0xffffffff) + (sum >> 32); + sum = (sum & 0xffffffff) + (sum >> 32); + + return csum_fold((__u32)sum); +} + +static __always_inline __u64 tcp_clock_ns(void) +{ + return bpf_ktime_get_ns(); +} + +static __always_inline __u32 tcp_ns_to_ts(__u64 ns) +{ + return ns / (NSEC_PER_SEC / TCP_TS_HZ); +} + +static __always_inline __u32 tcp_time_stamp_raw(void) +{ + return tcp_ns_to_ts(tcp_clock_ns()); +} + +struct tcpopt_context { + __u8 *ptr; + __u8 *end; + void *data_end; + __be32 *tsecr; + __u8 wscale; + bool option_timestamp; + bool option_sack; +}; + +static int tscookie_tcpopt_parse(struct tcpopt_context *ctx) +{ + __u8 opcode, opsize; + + if (ctx->ptr >= ctx->end) + return 1; + if (ctx->ptr >= ctx->data_end) + return 1; + + opcode = ctx->ptr[0]; + + if (opcode == TCPOPT_EOL) + return 1; + if (opcode == TCPOPT_NOP) { + ++ctx->ptr; + return 0; + } + + if (ctx->ptr + 1 >= ctx->end) + return 1; + if (ctx->ptr + 1 >= ctx->data_end) + return 1; + opsize = ctx->ptr[1]; + if (opsize < 2) + return 1; + + if (ctx->ptr + opsize > ctx->end) + return 1; + + switch (opcode) { + case TCPOPT_WINDOW: + if (opsize == TCPOLEN_WINDOW && ctx->ptr + TCPOLEN_WINDOW <= ctx->data_end) + ctx->wscale = ctx->ptr[2] < TCP_MAX_WSCALE ? ctx->ptr[2] : TCP_MAX_WSCALE; + break; + case TCPOPT_TIMESTAMP: + if (opsize == TCPOLEN_TIMESTAMP && ctx->ptr + TCPOLEN_TIMESTAMP <= ctx->data_end) { + ctx->option_timestamp = true; + /* Client's tsval becomes our tsecr. */ + *ctx->tsecr = get_unaligned((__be32 *)(ctx->ptr + 2)); + } + break; + case TCPOPT_SACK_PERM: + if (opsize == TCPOLEN_SACK_PERM) + ctx->option_sack = true; + break; + } + + ctx->ptr += opsize; + + return 0; +} + +static int tscookie_tcpopt_parse_batch(__u32 index, void *context) +{ + int i; + + for (i = 0; i < 7; i++) + if (tscookie_tcpopt_parse(context)) + return 1; + return 0; +} + +static __always_inline bool tscookie_init(struct tcphdr *tcp_header, + __u16 tcp_len, __be32 *tsval, + __be32 *tsecr, void *data_end) +{ + struct tcpopt_context loop_ctx = { + .ptr = (__u8 *)(tcp_header + 1), + .end = (__u8 *)tcp_header + tcp_len, + .data_end = data_end, + .tsecr = tsecr, + .wscale = TS_OPT_WSCALE_MASK, + .option_timestamp = false, + .option_sack = false, + }; + u32 cookie; + + bpf_loop(6, tscookie_tcpopt_parse_batch, &loop_ctx, 0); + + if (!loop_ctx.option_timestamp) + return false; + + cookie = tcp_time_stamp_raw() & ~TSMASK; + cookie |= loop_ctx.wscale & TS_OPT_WSCALE_MASK; + if (loop_ctx.option_sack) + cookie |= TS_OPT_SACK; + if (tcp_header->ece && tcp_header->cwr) + cookie |= TS_OPT_ECN; + *tsval = bpf_htonl(cookie); + + return true; +} + +static __always_inline void values_get_tcpipopts(__u16 *mss, __u8 *wscale, + __u8 *ttl, bool ipv6) +{ + __u32 key = 0; + __u64 *value; + + value = bpf_map_lookup_elem(&values, &key); + if (value && *value != 0) { + if (ipv6) + *mss = (*value >> 32) & 0xffff; + else + *mss = *value & 0xffff; + *wscale = (*value >> 16) & 0xf; + *ttl = (*value >> 24) & 0xff; + return; + } + + *mss = ipv6 ? DEFAULT_MSS6 : DEFAULT_MSS4; + *wscale = DEFAULT_WSCALE; + *ttl = DEFAULT_TTL; +} + +static __always_inline void values_inc_synacks(void) +{ + __u32 key = 1; + __u32 *value; + + value = bpf_map_lookup_elem(&values, &key); + if (value) + __sync_fetch_and_add(value, 1); +} + +static __always_inline bool check_port_allowed(__u16 port) +{ + __u32 i; + + for (i = 0; i < MAX_ALLOWED_PORTS; i++) { + __u32 key = i; + __u16 *value; + + value = bpf_map_lookup_elem(&allowed_ports, &key); + + if (!value) + break; + // 0 is a terminator value. Check it first to avoid matching on + // a forbidden port == 0 and returning true. + if (*value == 0) + break; + + if (*value == port) + return true; + } + + return false; +} + +struct header_pointers { + struct ethhdr *eth; + struct iphdr *ipv4; + struct ipv6hdr *ipv6; + struct tcphdr *tcp; + __u16 tcp_len; +}; + +static __always_inline int tcp_dissect(void *data, void *data_end, + struct header_pointers *hdr) +{ + hdr->eth = data; + if (hdr->eth + 1 > data_end) + return XDP_DROP; + + switch (bpf_ntohs(hdr->eth->h_proto)) { + case ETH_P_IP: + hdr->ipv6 = NULL; + + hdr->ipv4 = (void *)hdr->eth + sizeof(*hdr->eth); + if (hdr->ipv4 + 1 > data_end) + return XDP_DROP; + if (hdr->ipv4->ihl * 4 < sizeof(*hdr->ipv4)) + return XDP_DROP; + if (hdr->ipv4->version != 4) + return XDP_DROP; + + if (hdr->ipv4->protocol != IPPROTO_TCP) + return XDP_PASS; + + hdr->tcp = (void *)hdr->ipv4 + hdr->ipv4->ihl * 4; + break; + case ETH_P_IPV6: + hdr->ipv4 = NULL; + + hdr->ipv6 = (void *)hdr->eth + sizeof(*hdr->eth); + if (hdr->ipv6 + 1 > data_end) + return XDP_DROP; + if (hdr->ipv6->version != 6) + return XDP_DROP; + + // XXX: Extension headers are not supported and could circumvent + // XDP SYN flood protection. + if (hdr->ipv6->nexthdr != NEXTHDR_TCP) + return XDP_PASS; + + hdr->tcp = (void *)hdr->ipv6 + sizeof(*hdr->ipv6); + break; + default: + // XXX: VLANs will circumvent XDP SYN flood protection. + return XDP_PASS; + } + + if (hdr->tcp + 1 > data_end) + return XDP_DROP; + hdr->tcp_len = hdr->tcp->doff * 4; + if (hdr->tcp_len < sizeof(*hdr->tcp)) + return XDP_DROP; + + return XDP_TX; +} + +static __always_inline int tcp_lookup(struct xdp_md *ctx, struct header_pointers *hdr) +{ + struct bpf_ct_opts ct_lookup_opts = { + .netns_id = BPF_F_CURRENT_NETNS, + .l4proto = IPPROTO_TCP, + }; + struct bpf_sock_tuple tup = {}; + struct nf_conn *ct; + __u32 tup_size; + + if (hdr->ipv4) { + // TCP doesn't normally use fragments, and XDP can't reassemble them. + if ((hdr->ipv4->frag_off & bpf_htons(IP_DF | IP_MF | IP_OFFSET)) != bpf_htons(IP_DF)) + return XDP_DROP; + + tup.ipv4.saddr = hdr->ipv4->saddr; + tup.ipv4.daddr = hdr->ipv4->daddr; + tup.ipv4.sport = hdr->tcp->source; + tup.ipv4.dport = hdr->tcp->dest; + tup_size = sizeof(tup.ipv4); + } else if (hdr->ipv6) { + __builtin_memcpy(tup.ipv6.saddr, &hdr->ipv6->saddr, sizeof(tup.ipv6.saddr)); + __builtin_memcpy(tup.ipv6.daddr, &hdr->ipv6->daddr, sizeof(tup.ipv6.daddr)); + tup.ipv6.sport = hdr->tcp->source; + tup.ipv6.dport = hdr->tcp->dest; + tup_size = sizeof(tup.ipv6); + } else { + // The verifier can't track that either ipv4 or ipv6 is not NULL. + return XDP_ABORTED; + } + ct = bpf_xdp_ct_lookup(ctx, &tup, tup_size, &ct_lookup_opts, sizeof(ct_lookup_opts)); + if (ct) { + unsigned long status = ct->status; + + bpf_ct_release(ct); + if (status & IPS_CONFIRMED_BIT) + return XDP_PASS; + } else if (ct_lookup_opts.error != -ENOENT) { + return XDP_ABORTED; + } + + // error == -ENOENT || !(status & IPS_CONFIRMED_BIT) + return XDP_TX; +} + +static __always_inline __u8 tcp_mkoptions(__be32 *buf, __be32 *tsopt, __u16 mss, + __u8 wscale) +{ + __be32 *start = buf; + + *buf++ = bpf_htonl((TCPOPT_MSS << 24) | (TCPOLEN_MSS << 16) | mss); + + if (!tsopt) + return buf - start; + + if (tsopt[0] & bpf_htonl(1 << 4)) + *buf++ = bpf_htonl((TCPOPT_SACK_PERM << 24) | + (TCPOLEN_SACK_PERM << 16) | + (TCPOPT_TIMESTAMP << 8) | + TCPOLEN_TIMESTAMP); + else + *buf++ = bpf_htonl((TCPOPT_NOP << 24) | + (TCPOPT_NOP << 16) | + (TCPOPT_TIMESTAMP << 8) | + TCPOLEN_TIMESTAMP); + *buf++ = tsopt[0]; + *buf++ = tsopt[1]; + + if ((tsopt[0] & bpf_htonl(0xf)) != bpf_htonl(0xf)) + *buf++ = bpf_htonl((TCPOPT_NOP << 24) | + (TCPOPT_WINDOW << 16) | + (TCPOLEN_WINDOW << 8) | + wscale); + + return buf - start; +} + +static __always_inline void tcp_gen_synack(struct tcphdr *tcp_header, + __u32 cookie, __be32 *tsopt, + __u16 mss, __u8 wscale) +{ + void *tcp_options; + + tcp_flag_word(tcp_header) = TCP_FLAG_SYN | TCP_FLAG_ACK; + if (tsopt && (tsopt[0] & bpf_htonl(1 << 5))) + tcp_flag_word(tcp_header) |= TCP_FLAG_ECE; + tcp_header->doff = 5; // doff is part of tcp_flag_word. + swap(tcp_header->source, tcp_header->dest); + tcp_header->ack_seq = bpf_htonl(bpf_ntohl(tcp_header->seq) + 1); + tcp_header->seq = bpf_htonl(cookie); + tcp_header->window = 0; + tcp_header->urg_ptr = 0; + tcp_header->check = 0; // Rely on hardware checksum offload. + + tcp_options = (void *)(tcp_header + 1); + tcp_header->doff += tcp_mkoptions(tcp_options, tsopt, mss, wscale); +} + +static __always_inline void tcpv4_gen_synack(struct header_pointers *hdr, + __u32 cookie, __be32 *tsopt) +{ + __u8 wscale; + __u16 mss; + __u8 ttl; + + values_get_tcpipopts(&mss, &wscale, &ttl, false); + + swap_eth_addr(hdr->eth->h_source, hdr->eth->h_dest); + + swap(hdr->ipv4->saddr, hdr->ipv4->daddr); + hdr->ipv4->check = 0; // Rely on hardware checksum offload. + hdr->ipv4->tos = 0; + hdr->ipv4->id = 0; + hdr->ipv4->ttl = ttl; + + tcp_gen_synack(hdr->tcp, cookie, tsopt, mss, wscale); + + hdr->tcp_len = hdr->tcp->doff * 4; + hdr->ipv4->tot_len = bpf_htons(sizeof(*hdr->ipv4) + hdr->tcp_len); +} + +static __always_inline void tcpv6_gen_synack(struct header_pointers *hdr, + __u32 cookie, __be32 *tsopt) +{ + __u8 wscale; + __u16 mss; + __u8 ttl; + + values_get_tcpipopts(&mss, &wscale, &ttl, true); + + swap_eth_addr(hdr->eth->h_source, hdr->eth->h_dest); + + swap(hdr->ipv6->saddr, hdr->ipv6->daddr); + *(__be32 *)hdr->ipv6 = bpf_htonl(0x60000000); + hdr->ipv6->hop_limit = ttl; + + tcp_gen_synack(hdr->tcp, cookie, tsopt, mss, wscale); + + hdr->tcp_len = hdr->tcp->doff * 4; + hdr->ipv6->payload_len = bpf_htons(hdr->tcp_len); +} + +static __always_inline int syncookie_handle_syn(struct header_pointers *hdr, + struct xdp_md *ctx, + void *data, void *data_end) +{ + __u32 old_pkt_size, new_pkt_size; + // Unlike clang 10, clang 11 and 12 generate code that doesn't pass the + // BPF verifier if tsopt is not volatile. Volatile forces it to store + // the pointer value and use it directly, otherwise tcp_mkoptions is + // (mis)compiled like this: + // if (!tsopt) + // return buf - start; + // reg = stored_return_value_of_bpf_tcp_raw_gen_tscookie; + // if (reg == 0) + // tsopt = tsopt_buf; + // else + // tsopt = NULL; + // ... + // *buf++ = tsopt[1]; + // It creates a dead branch where tsopt is assigned NULL, but the + // verifier can't prove it's dead and blocks the program. + __be32 * volatile tsopt = NULL; + __be32 tsopt_buf[2] = {}; + void *ip_header; + __u16 ip_len; + __u32 cookie; + __s64 value; + + if (hdr->ipv4) { + // Check the IPv4 and TCP checksums before creating a SYNACK. + value = bpf_csum_diff(0, 0, (void *)hdr->ipv4, hdr->ipv4->ihl * 4, 0); + if (value < 0) + return XDP_ABORTED; + if (csum_fold(value) != 0) + return XDP_DROP; // Bad IPv4 checksum. + + value = bpf_csum_diff(0, 0, (void *)hdr->tcp, hdr->tcp_len, 0); + if (value < 0) + return XDP_ABORTED; + if (csum_tcpudp_magic(hdr->ipv4->saddr, hdr->ipv4->daddr, + hdr->tcp_len, IPPROTO_TCP, value) != 0) + return XDP_DROP; // Bad TCP checksum. + + ip_header = hdr->ipv4; + ip_len = sizeof(*hdr->ipv4); + } else if (hdr->ipv6) { + // Check the TCP checksum before creating a SYNACK. + value = bpf_csum_diff(0, 0, (void *)hdr->tcp, hdr->tcp_len, 0); + if (value < 0) + return XDP_ABORTED; + if (csum_ipv6_magic(&hdr->ipv6->saddr, &hdr->ipv6->daddr, + hdr->tcp_len, IPPROTO_TCP, value) != 0) + return XDP_DROP; // Bad TCP checksum. + + ip_header = hdr->ipv6; + ip_len = sizeof(*hdr->ipv6); + } else { + return XDP_ABORTED; + } + + // Issue SYN cookies on allowed ports, drop SYN packets on + // blocked ports. + if (!check_port_allowed(bpf_ntohs(hdr->tcp->dest))) + return XDP_DROP; + + value = bpf_tcp_raw_gen_syncookie(ip_header, ip_len, + (void *)hdr->tcp, hdr->tcp_len); + if (value < 0) + return XDP_ABORTED; + cookie = (__u32)value; + + if (tscookie_init((void *)hdr->tcp, hdr->tcp_len, + &tsopt_buf[0], &tsopt_buf[1], data_end)) + tsopt = tsopt_buf; + + // Check that there is enough space for a SYNACK. It also covers + // the check that the destination of the __builtin_memmove below + // doesn't overflow. + if (data + sizeof(*hdr->eth) + ip_len + TCP_MAXLEN > data_end) + return XDP_ABORTED; + + if (hdr->ipv4) { + if (hdr->ipv4->ihl * 4 > sizeof(*hdr->ipv4)) { + struct tcphdr *new_tcp_header; + + new_tcp_header = data + sizeof(*hdr->eth) + sizeof(*hdr->ipv4); + __builtin_memmove(new_tcp_header, hdr->tcp, sizeof(*hdr->tcp)); + hdr->tcp = new_tcp_header; + + hdr->ipv4->ihl = sizeof(*hdr->ipv4) / 4; + } + + tcpv4_gen_synack(hdr, cookie, tsopt); + } else if (hdr->ipv6) { + tcpv6_gen_synack(hdr, cookie, tsopt); + } else { + return XDP_ABORTED; + } + + // Recalculate checksums. + hdr->tcp->check = 0; + value = bpf_csum_diff(0, 0, (void *)hdr->tcp, hdr->tcp_len, 0); + if (value < 0) + return XDP_ABORTED; + if (hdr->ipv4) { + hdr->tcp->check = csum_tcpudp_magic(hdr->ipv4->saddr, + hdr->ipv4->daddr, + hdr->tcp_len, + IPPROTO_TCP, + value); + + hdr->ipv4->check = 0; + value = bpf_csum_diff(0, 0, (void *)hdr->ipv4, sizeof(*hdr->ipv4), 0); + if (value < 0) + return XDP_ABORTED; + hdr->ipv4->check = csum_fold(value); + } else if (hdr->ipv6) { + hdr->tcp->check = csum_ipv6_magic(&hdr->ipv6->saddr, + &hdr->ipv6->daddr, + hdr->tcp_len, + IPPROTO_TCP, + value); + } else { + return XDP_ABORTED; + } + + // Set the new packet size. + old_pkt_size = data_end - data; + new_pkt_size = sizeof(*hdr->eth) + ip_len + hdr->tcp->doff * 4; + if (bpf_xdp_adjust_tail(ctx, new_pkt_size - old_pkt_size)) + return XDP_ABORTED; + + values_inc_synacks(); + + return XDP_TX; +} + +static __always_inline int syncookie_handle_ack(struct header_pointers *hdr) +{ + int err; + + if (hdr->ipv4) + err = bpf_tcp_raw_check_syncookie(hdr->ipv4, sizeof(*hdr->ipv4), + (void *)hdr->tcp, hdr->tcp_len); + else if (hdr->ipv6) + err = bpf_tcp_raw_check_syncookie(hdr->ipv6, sizeof(*hdr->ipv6), + (void *)hdr->tcp, hdr->tcp_len); + else + return XDP_ABORTED; + if (err) + return XDP_DROP; + + return XDP_PASS; +} + +SEC("xdp/syncookie") +int syncookie_xdp(struct xdp_md *ctx) +{ + void *data_end = (void *)(long)ctx->data_end; + void *data = (void *)(long)ctx->data; + struct header_pointers hdr; + __s64 value; + int ret; + + struct bpf_ct_opts ct_lookup_opts = { + .netns_id = BPF_F_CURRENT_NETNS, + .l4proto = IPPROTO_TCP, + }; + + ret = tcp_dissect(data, data_end, &hdr); + if (ret != XDP_TX) + return ret; + + ret = tcp_lookup(ctx, &hdr); + if (ret != XDP_TX) + return ret; + + // Packet is TCP and doesn't belong to an established connection. + + if ((hdr.tcp->syn ^ hdr.tcp->ack) != 1) + return XDP_DROP; + + // Grow the TCP header to TCP_MAXLEN to be able to pass any hdr.tcp_len + // to bpf_tcp_raw_gen_syncookie and pass the verifier. + if (bpf_xdp_adjust_tail(ctx, TCP_MAXLEN - hdr.tcp_len)) + return XDP_ABORTED; + + data_end = (void *)(long)ctx->data_end; + data = (void *)(long)ctx->data; + + if (hdr.ipv4) { + hdr.eth = data; + hdr.ipv4 = (void *)hdr.eth + sizeof(*hdr.eth); + // IPV4_MAXLEN is needed when calculating checksum. + // At least sizeof(struct iphdr) is needed here to access ihl. + if ((void *)hdr.ipv4 + IPV4_MAXLEN > data_end) + return XDP_ABORTED; + hdr.tcp = (void *)hdr.ipv4 + hdr.ipv4->ihl * 4; + } else if (hdr.ipv6) { + hdr.eth = data; + hdr.ipv6 = (void *)hdr.eth + sizeof(*hdr.eth); + hdr.tcp = (void *)hdr.ipv6 + sizeof(*hdr.ipv6); + } else { + return XDP_ABORTED; + } + + if ((void *)hdr.tcp + TCP_MAXLEN > data_end) + return XDP_ABORTED; + + // We run out of registers, tcp_len gets spilled to the stack, and the + // verifier forgets its min and max values checked above in tcp_dissect. + hdr.tcp_len = hdr.tcp->doff * 4; + if (hdr.tcp_len < sizeof(*hdr.tcp)) + return XDP_ABORTED; + + return hdr.tcp->syn ? syncookie_handle_syn(&hdr, ctx, data, data_end) : + syncookie_handle_ack(&hdr); +} + +char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/test_xdp_synproxy.sh b/tools/testing/selftests/bpf/test_xdp_synproxy.sh new file mode 100755 index 000000000000..8f2811983212 --- /dev/null +++ b/tools/testing/selftests/bpf/test_xdp_synproxy.sh @@ -0,0 +1,71 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB +# Copyright (c) 2021, NVIDIA CORPORATION & AFFILIATES. All rights reserved. + +set -e + +PORT=8080 + +DIR="$(dirname "$0")" +SERVER_PID= + +fail() { + echo 'test_xdp_synproxy: [FAIL]' + exit 1 +} + +cleanup() { + set +e + + ip link del tmp0 + ip netns del synproxy + + # Kill background jobs, if any. + kill "$(jobs -p)" +} + +trap cleanup SIGINT SIGTERM EXIT + +modprobe nf_conntrack +ip netns add synproxy +ip netns exec synproxy ip link set lo up +ip link add tmp0 type veth peer name tmp1 +sleep 1 # Wait, otherwise the IP address is not applied to tmp0. +ip link set tmp1 netns synproxy +ip link set tmp0 up +ip addr replace 198.18.0.1/24 dev tmp0 +ip netns exec synproxy ip link set tmp1 up +ip netns exec synproxy ip addr replace 198.18.0.2/24 dev tmp1 +ip netns exec synproxy sysctl -w net.ipv4.tcp_syncookies=2 +ip netns exec synproxy sysctl -w net.ipv4.tcp_timestamps=1 +ip netns exec synproxy sysctl -w net.netfilter.nf_conntrack_tcp_loose=0 +ip netns exec synproxy iptables -t raw -I PREROUTING \ + -i tmp1 -p tcp -m tcp --syn --dport "$PORT" -j CT --notrack +ip netns exec synproxy iptables -t filter -A INPUT \ + -i tmp1 -p tcp -m tcp --dport "$PORT" -m state --state INVALID,UNTRACKED \ + -j SYNPROXY --sack-perm --timestamp --wscale 7 --mss 1460 +ip netns exec synproxy iptables -t filter -A INPUT \ + -i tmp1 -m state --state INVALID -j DROP +# When checksum offload is enabled, the XDP program sees wrong checksums and +# drops packets. +ethtool -K tmp0 tx off +# Workaround required for veth. +ip link set tmp0 xdp object "$DIR/xdp_dummy.o" section xdp 2> /dev/null + +SYNACKS="$(ip netns exec synproxy "$DIR/xdp_synproxy" --iface tmp1 \ + --ports "$PORT" --mss4 1460 --mss6 1440 --wscale 7 --ttl 64 --single | \ + cut -d: -f2)" +[ "$SYNACKS" -eq 0 ] || fail + +# Different nc implementations accept different parameters. +{ ip netns exec synproxy nc -l -p "$PORT" || ip netns exec synproxy nc -l "$PORT"; } & +SERVER_PID="$!" +sleep 1 # Wait for the server to start. + +echo -n > /dev/tcp/198.18.0.2/"$PORT" + +SYNACKS="$(ip netns exec synproxy "$DIR/xdp_synproxy" --iface tmp1 --single | \ + cut -d: -f2)" +[ "$SYNACKS" -eq 1 ] || fail + +echo 'test_xdp_synproxy: ok' diff --git a/tools/testing/selftests/bpf/xdp_synproxy.c b/tools/testing/selftests/bpf/xdp_synproxy.c new file mode 100644 index 000000000000..e27e86a82a4f --- /dev/null +++ b/tools/testing/selftests/bpf/xdp_synproxy.c @@ -0,0 +1,418 @@ +// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB +/* Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES. All rights reserved. */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static unsigned int ifindex; +static __u32 attached_prog_id; + +static void noreturn cleanup(int sig) +{ + DECLARE_LIBBPF_OPTS(bpf_xdp_set_link_opts, opts); + int prog_fd; + int err; + + if (attached_prog_id == 0) + exit(0); + + prog_fd = bpf_prog_get_fd_by_id(attached_prog_id); + if (prog_fd < 0) { + fprintf(stderr, "Error: bpf_prog_get_fd_by_id: %s\n", strerror(-prog_fd)); + err = bpf_set_link_xdp_fd(ifindex, -1, 0); + if (err < 0) { + fprintf(stderr, "Error: bpf_set_link_xdp_fd: %s\n", strerror(-err)); + fprintf(stderr, "Failed to detach XDP program\n"); + exit(1); + } + } else { + opts.old_fd = prog_fd; + err = bpf_set_link_xdp_fd_opts(ifindex, -1, XDP_FLAGS_REPLACE, &opts); + close(prog_fd); + if (err < 0) { + fprintf(stderr, "Error: bpf_set_link_xdp_fd_opts: %s\n", strerror(-err)); + // Not an error if already replaced by someone else. + if (err != -EEXIST) { + fprintf(stderr, "Failed to detach XDP program\n"); + exit(1); + } + } + } + exit(0); +} + +static noreturn void usage(const char *progname) +{ + fprintf(stderr, "Usage: %s [--iface |--prog ] [--mss4 --mss6 --wscale --ttl ] [--ports ,,...] [--single]\n", + progname); + exit(1); +} + +static unsigned long parse_arg_ul(const char *progname, const char *arg, unsigned long limit) +{ + unsigned long res; + char *endptr; + + errno = 0; + res = strtoul(arg, &endptr, 10); + if (errno != 0 || *endptr != '\0' || arg[0] == '\0' || res > limit) + usage(progname); + + return res; +} + +static void parse_options(int argc, char *argv[], unsigned int *ifindex, __u32 *prog_id, + __u64 *tcpipopts, char **ports, bool *single) +{ + static struct option long_options[] = { + { "help", no_argument, NULL, 'h' }, + { "iface", required_argument, NULL, 'i' }, + { "prog", required_argument, NULL, 'x' }, + { "mss4", required_argument, NULL, 4 }, + { "mss6", required_argument, NULL, 6 }, + { "wscale", required_argument, NULL, 'w' }, + { "ttl", required_argument, NULL, 't' }, + { "ports", required_argument, NULL, 'p' }, + { "single", no_argument, NULL, 's' }, + { NULL, 0, NULL, 0 }, + }; + unsigned long mss4, mss6, wscale, ttl; + unsigned int tcpipopts_mask = 0; + + if (argc < 2) + usage(argv[0]); + + *ifindex = 0; + *prog_id = 0; + *tcpipopts = 0; + *ports = NULL; + *single = false; + + while (true) { + int opt; + + opt = getopt_long(argc, argv, "", long_options, NULL); + if (opt == -1) + break; + + switch (opt) { + case 'h': + usage(argv[0]); + break; + case 'i': + *ifindex = if_nametoindex(optarg); + if (*ifindex == 0) + usage(argv[0]); + break; + case 'x': + *prog_id = parse_arg_ul(argv[0], optarg, UINT32_MAX); + if (*prog_id == 0) + usage(argv[0]); + break; + case 4: + mss4 = parse_arg_ul(argv[0], optarg, UINT16_MAX); + tcpipopts_mask |= 1 << 0; + break; + case 6: + mss6 = parse_arg_ul(argv[0], optarg, UINT16_MAX); + tcpipopts_mask |= 1 << 1; + break; + case 'w': + wscale = parse_arg_ul(argv[0], optarg, 14); + tcpipopts_mask |= 1 << 2; + break; + case 't': + ttl = parse_arg_ul(argv[0], optarg, UINT8_MAX); + tcpipopts_mask |= 1 << 3; + break; + case 'p': + *ports = optarg; + break; + case 's': + *single = true; + break; + default: + usage(argv[0]); + } + } + if (optind < argc) + usage(argv[0]); + + if (tcpipopts_mask == 0xf) { + if (mss4 == 0 || mss6 == 0 || wscale == 0 || ttl == 0) + usage(argv[0]); + *tcpipopts = (mss6 << 32) | (ttl << 24) | (wscale << 16) | mss4; + } else if (tcpipopts_mask != 0) { + usage(argv[0]); + } + + if (*ifindex != 0 && *prog_id != 0) + usage(argv[0]); + if (*ifindex == 0 && *prog_id == 0) + usage(argv[0]); +} + +static int syncookie_attach(const char *argv0, unsigned int ifindex) +{ + struct bpf_prog_info info = {}; + __u32 info_len = sizeof(info); + char xdp_filename[PATH_MAX]; + struct bpf_program *prog; + struct bpf_object *obj; + int prog_fd; + int err; + + snprintf(xdp_filename, sizeof(xdp_filename), "%s_kern.o", argv0); + obj = bpf_object__open_file(xdp_filename, NULL); + err = libbpf_get_error(obj); + if (err < 0) { + fprintf(stderr, "Error: bpf_object__open_file: %s\n", strerror(-err)); + return err; + } + + err = bpf_object__load(obj); + if (err < 0) { + fprintf(stderr, "Error: bpf_object__open_file: %s\n", strerror(-err)); + return err; + } + + prog = bpf_object__find_program_by_name(obj, "syncookie_xdp"); + if (!prog) { + fprintf(stderr, "Error: bpf_object__find_program_by_name: program syncookie_xdp was not found\n"); + return -ENOENT; + } + + prog_fd = bpf_program__fd(prog); + + err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len); + if (err < 0) { + fprintf(stderr, "Error: bpf_obj_get_info_by_fd: %s\n", strerror(-err)); + goto out; + } + attached_prog_id = info.id; + signal(SIGINT, cleanup); + signal(SIGTERM, cleanup); + err = bpf_set_link_xdp_fd(ifindex, prog_fd, XDP_FLAGS_UPDATE_IF_NOEXIST); + if (err < 0) { + fprintf(stderr, "Error: bpf_set_link_xdp_fd: %s\n", strerror(-err)); + signal(SIGINT, SIG_DFL); + signal(SIGTERM, SIG_DFL); + attached_prog_id = 0; + goto out; + } + err = 0; +out: + bpf_object__close(obj); + return err; +} + +static int syncookie_open_bpf_maps(__u32 prog_id, int *values_map_fd, int *ports_map_fd) +{ + struct bpf_prog_info prog_info; + __u32 map_ids[8]; + __u32 info_len; + int prog_fd; + int err; + int i; + + *values_map_fd = -1; + *ports_map_fd = -1; + + prog_fd = bpf_prog_get_fd_by_id(prog_id); + if (prog_fd < 0) { + fprintf(stderr, "Error: bpf_prog_get_fd_by_id: %s\n", strerror(-prog_fd)); + return prog_fd; + } + + prog_info = (struct bpf_prog_info) { + .nr_map_ids = 8, + .map_ids = (__u64)map_ids, + }; + info_len = sizeof(prog_info); + + err = bpf_obj_get_info_by_fd(prog_fd, &prog_info, &info_len); + if (err != 0) { + fprintf(stderr, "Error: bpf_obj_get_info_by_fd: %s\n", strerror(-err)); + goto out; + } + + if (prog_info.type != BPF_PROG_TYPE_XDP) { + fprintf(stderr, "Error: BPF prog type is not BPF_PROG_TYPE_XDP\n"); + err = -ENOENT; + goto out; + } + if (prog_info.nr_map_ids < 2) { + fprintf(stderr, "Error: Found %u BPF maps, expected at least 2\n", + prog_info.nr_map_ids); + err = -ENOENT; + goto out; + } + + for (i = 0; i < prog_info.nr_map_ids; i++) { + struct bpf_map_info map_info = {}; + int map_fd; + + err = bpf_map_get_fd_by_id(map_ids[i]); + if (err < 0) { + fprintf(stderr, "Error: bpf_map_get_fd_by_id: %s\n", strerror(-err)); + goto err_close_map_fds; + } + map_fd = err; + + info_len = sizeof(map_info); + err = bpf_obj_get_info_by_fd(map_fd, &map_info, &info_len); + if (err != 0) { + fprintf(stderr, "Error: bpf_obj_get_info_by_fd: %s\n", strerror(-err)); + close(map_fd); + goto err_close_map_fds; + } + if (strcmp(map_info.name, "values") == 0) { + *values_map_fd = map_fd; + continue; + } + if (strcmp(map_info.name, "allowed_ports") == 0) { + *ports_map_fd = map_fd; + continue; + } + close(map_fd); + } + + if (*values_map_fd != -1 && *ports_map_fd != -1) { + err = 0; + goto out; + } + + err = -ENOENT; + +err_close_map_fds: + if (*values_map_fd != -1) + close(*values_map_fd); + if (*ports_map_fd != -1) + close(*ports_map_fd); + *values_map_fd = -1; + *ports_map_fd = -1; + +out: + close(prog_fd); + return err; +} + +int main(int argc, char *argv[]) +{ + int values_map_fd, ports_map_fd; + __u64 tcpipopts; + bool firstiter; + __u64 prevcnt; + __u32 prog_id; + char *ports; + bool single; + int err = 0; + + parse_options(argc, argv, &ifindex, &prog_id, &tcpipopts, &ports, &single); + + if (prog_id == 0) { + err = bpf_get_link_xdp_id(ifindex, &prog_id, 0); + if (err < 0) { + fprintf(stderr, "Error: bpf_get_link_xdp_id: %s\n", strerror(-err)); + goto out; + } + if (prog_id == 0) { + err = syncookie_attach(argv[0], ifindex); + if (err < 0) + goto out; + prog_id = attached_prog_id; + } + } + + err = syncookie_open_bpf_maps(prog_id, &values_map_fd, &ports_map_fd); + if (err < 0) + goto out; + + if (ports) { + __u16 port_last = 0; + __u32 port_idx = 0; + char *p = ports; + + fprintf(stderr, "Replacing allowed ports\n"); + + while (p && *p != '\0') { + char *token = strsep(&p, ","); + __u16 port; + + port = parse_arg_ul(argv[0], token, UINT16_MAX); + err = bpf_map_update_elem(ports_map_fd, &port_idx, &port, BPF_ANY); + if (err != 0) { + fprintf(stderr, "Error: bpf_map_update_elem: %s\n", strerror(-err)); + fprintf(stderr, "Failed to add port %u (index %u)\n", + port, port_idx); + goto out_close_maps; + } + fprintf(stderr, "Added port %u\n", port); + port_idx++; + } + err = bpf_map_update_elem(ports_map_fd, &port_idx, &port_last, BPF_ANY); + if (err != 0) { + fprintf(stderr, "Error: bpf_map_update_elem: %s\n", strerror(-err)); + fprintf(stderr, "Failed to add the terminator value 0 (index %u)\n", + port_idx); + goto out_close_maps; + } + } + + if (tcpipopts) { + __u32 key = 0; + + fprintf(stderr, "Replacing TCP/IP options\n"); + + err = bpf_map_update_elem(values_map_fd, &key, &tcpipopts, BPF_ANY); + if (err != 0) { + fprintf(stderr, "Error: bpf_map_update_elem: %s\n", strerror(-err)); + goto out_close_maps; + } + } + + if ((ports || tcpipopts) && attached_prog_id == 0 && !single) + goto out_close_maps; + + prevcnt = 0; + firstiter = true; + while (true) { + __u32 key = 1; + __u64 value; + + err = bpf_map_lookup_elem(values_map_fd, &key, &value); + if (err != 0) { + fprintf(stderr, "Error: bpf_map_lookup_elem: %s\n", strerror(-err)); + goto out_close_maps; + } + if (firstiter) { + prevcnt = value; + firstiter = false; + } + if (single) { + printf("Total SYNACKs generated: %llu\n", value); + break; + } + printf("SYNACKs generated: %llu (total %llu)\n", value - prevcnt, value); + prevcnt = value; + sleep(1); + } + +out_close_maps: + close(values_map_fd); + close(ports_map_fd); +out: + return err == 0 ? 0 : 1; +}