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([10.190.162.156]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Feb 2025 01:10:04 -0800 From: Tushar Vyavahare To: bpf@vger.kernel.org Cc: netdev@vger.kernel.org, bjorn@kernel.org, magnus.karlsson@intel.com, maciej.fijalkowski@intel.com, jonathan.lemon@gmail.com, davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, ast@kernel.org, daniel@iogearbox.net, tushar.vyavahare@intel.com Subject: [PATCH bpf-next 2/6] selftests/xsk: Add tail adjustment functionality to XDP Date: Thu, 20 Feb 2025 08:41:43 +0000 Message-Id: <20250220084147.94494-3-tushar.vyavahare@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250220084147.94494-1-tushar.vyavahare@intel.com> References: <20250220084147.94494-1-tushar.vyavahare@intel.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net Introduce a new function, xsk_xdp_adjust_tail, within the XDP program to adjust the tail of packets. This function utilizes bpf_xdp_adjust_tail to modify the packet size dynamically based on the 'count' variable. If the adjustment fails, the packet is dropped using XDP_DROP to ensure processing of only correctly modified packets. Signed-off-by: Tushar Vyavahare --- .../selftests/bpf/progs/xsk_xdp_progs.c | 48 +++++++++++++++++++ tools/testing/selftests/bpf/xsk_xdp_common.h | 1 + 2 files changed, 49 insertions(+) diff --git a/tools/testing/selftests/bpf/progs/xsk_xdp_progs.c b/tools/testing/selftests/bpf/progs/xsk_xdp_progs.c index ccde6a4c6319..2e8e2faf17e0 100644 --- a/tools/testing/selftests/bpf/progs/xsk_xdp_progs.c +++ b/tools/testing/selftests/bpf/progs/xsk_xdp_progs.c @@ -4,6 +4,8 @@ #include #include #include +#include +#include #include "xsk_xdp_common.h" struct { @@ -70,4 +72,50 @@ SEC("xdp") int xsk_xdp_shared_umem(struct xdp_md *xdp) return bpf_redirect_map(&xsk, idx, XDP_DROP); } +SEC("xdp.frags") int xsk_xdp_adjust_tail(struct xdp_md *xdp) +{ + __u32 buff_len, curr_buff_len; + int ret; + + buff_len = bpf_xdp_get_buff_len(xdp); + if (buff_len == 0) + return XDP_DROP; + + ret = bpf_xdp_adjust_tail(xdp, count); + if (ret < 0) { + /* Handle unsupported cases */ + if (ret == -EOPNOTSUPP) { + /* Set count to -EOPNOTSUPP to indicate to userspace that this case is + * unsupported + */ + count = -EOPNOTSUPP; + return bpf_redirect_map(&xsk, 0, XDP_DROP); + } + + return XDP_DROP; + } + + curr_buff_len = bpf_xdp_get_buff_len(xdp); + if (curr_buff_len != buff_len + count) + return XDP_DROP; + + if (curr_buff_len > buff_len) { + __u32 *pkt_data = (void *)(long)xdp->data; + __u32 len, words_to_end, seq_num; + + len = curr_buff_len - PKT_HDR_ALIGN; + words_to_end = len / sizeof(*pkt_data) - 1; + seq_num = words_to_end; + + /* Convert sequence number to network byte order. Store this in the last 4 bytes of + * the packet. Use 'count' to determine the position at the end of the packet for + * storing the sequence number. + */ + seq_num = __constant_htonl(words_to_end); + bpf_xdp_store_bytes(xdp, curr_buff_len - count, &seq_num, sizeof(seq_num)); + } + + return bpf_redirect_map(&xsk, 0, XDP_DROP); +} + char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/xsk_xdp_common.h b/tools/testing/selftests/bpf/xsk_xdp_common.h index 5a6f36f07383..45810ff552da 100644 --- a/tools/testing/selftests/bpf/xsk_xdp_common.h +++ b/tools/testing/selftests/bpf/xsk_xdp_common.h @@ -4,6 +4,7 @@ #define XSK_XDP_COMMON_H_ #define MAX_SOCKETS 2 +#define PKT_HDR_ALIGN (sizeof(struct ethhdr) + 2) /* Just to align the data in the packet */ struct xdp_info { __u64 count;