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Lee" To: Daniel Borkmann , Alexei Starovoitov Cc: netdev@vger.kernel.org, bpf@vger.kernel.org Subject: [bpf-next,v3] samples: bpf: add max_pckt_size option at xdp_adjust_tail Date: Thu, 12 Sep 2019 04:02:18 +0900 Message-Id: <20190911190218.22628-1-danieltimlee@gmail.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Currently, at xdp_adjust_tail_kern.c, MAX_PCKT_SIZE is limited to 600. To make this size flexible, a new map 'pcktsz' is added. By updating new packet size to this map from the userland, xdp_adjust_tail_kern.o will use this value as a new max_pckt_size. If no '-P ' option is used, the size of maximum packet will be 600 as a default. Signed-off-by: Daniel T. Lee --- Changes in v2: - Change the helper to fetch map from 'bpf_map__next' to 'bpf_object__find_map_fd_by_name'. samples/bpf/xdp_adjust_tail_kern.c | 23 +++++++++++++++++++---- samples/bpf/xdp_adjust_tail_user.c | 28 ++++++++++++++++++++++------ 2 files changed, 41 insertions(+), 10 deletions(-) diff --git a/samples/bpf/xdp_adjust_tail_kern.c b/samples/bpf/xdp_adjust_tail_kern.c index 411fdb21f8bc..d6d84ffe6a7a 100644 --- a/samples/bpf/xdp_adjust_tail_kern.c +++ b/samples/bpf/xdp_adjust_tail_kern.c @@ -25,6 +25,13 @@ #define ICMP_TOOBIG_SIZE 98 #define ICMP_TOOBIG_PAYLOAD_SIZE 92 +struct bpf_map_def SEC("maps") pcktsz = { + .type = BPF_MAP_TYPE_ARRAY, + .key_size = sizeof(__u32), + .value_size = sizeof(__u32), + .max_entries = 1, +}; + struct bpf_map_def SEC("maps") icmpcnt = { .type = BPF_MAP_TYPE_ARRAY, .key_size = sizeof(__u32), @@ -64,7 +71,8 @@ static __always_inline void ipv4_csum(void *data_start, int data_size, *csum = csum_fold_helper(*csum); } -static __always_inline int send_icmp4_too_big(struct xdp_md *xdp) +static __always_inline int send_icmp4_too_big(struct xdp_md *xdp, + __u32 max_pckt_size) { int headroom = (int)sizeof(struct iphdr) + (int)sizeof(struct icmphdr); @@ -92,7 +100,7 @@ static __always_inline int send_icmp4_too_big(struct xdp_md *xdp) orig_iph = data + off; icmp_hdr->type = ICMP_DEST_UNREACH; icmp_hdr->code = ICMP_FRAG_NEEDED; - icmp_hdr->un.frag.mtu = htons(MAX_PCKT_SIZE-sizeof(struct ethhdr)); + icmp_hdr->un.frag.mtu = htons(max_pckt_size - sizeof(struct ethhdr)); icmp_hdr->checksum = 0; ipv4_csum(icmp_hdr, ICMP_TOOBIG_PAYLOAD_SIZE, &csum); icmp_hdr->checksum = csum; @@ -118,14 +126,21 @@ static __always_inline int handle_ipv4(struct xdp_md *xdp) { void *data_end = (void *)(long)xdp->data_end; void *data = (void *)(long)xdp->data; + __u32 max_pckt_size = MAX_PCKT_SIZE; + __u32 *pckt_sz; + __u32 key = 0; int pckt_size = data_end - data; int offset; - if (pckt_size > MAX_PCKT_SIZE) { + pckt_sz = bpf_map_lookup_elem(&pcktsz, &key); + if (pckt_sz && *pckt_sz) + max_pckt_size = *pckt_sz; + + if (pckt_size > max_pckt_size) { offset = pckt_size - ICMP_TOOBIG_SIZE; if (bpf_xdp_adjust_tail(xdp, 0 - offset)) return XDP_PASS; - return send_icmp4_too_big(xdp); + return send_icmp4_too_big(xdp, max_pckt_size); } return XDP_PASS; } diff --git a/samples/bpf/xdp_adjust_tail_user.c b/samples/bpf/xdp_adjust_tail_user.c index a3596b617c4c..aef6c69a48a7 100644 --- a/samples/bpf/xdp_adjust_tail_user.c +++ b/samples/bpf/xdp_adjust_tail_user.c @@ -23,6 +23,7 @@ #include "libbpf.h" #define STATS_INTERVAL_S 2U +#define MAX_PCKT_SIZE 600 static int ifindex = -1; static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST; @@ -72,6 +73,7 @@ static void usage(const char *cmd) printf("Usage: %s [...]\n", cmd); printf(" -i Interface\n"); printf(" -T Default: 0 (forever)\n"); + printf(" -P Default: %u\n", MAX_PCKT_SIZE); printf(" -S use skb-mode\n"); printf(" -N enforce native mode\n"); printf(" -F force loading prog\n"); @@ -85,13 +87,14 @@ int main(int argc, char **argv) .prog_type = BPF_PROG_TYPE_XDP, }; unsigned char opt_flags[256] = {}; - const char *optstr = "i:T:SNFh"; + const char *optstr = "i:T:P:SNFh"; struct bpf_prog_info info = {}; __u32 info_len = sizeof(info); + __u32 max_pckt_size = 0; + __u32 key = 0; unsigned int kill_after_s = 0; int i, prog_fd, map_fd, opt; struct bpf_object *obj; - struct bpf_map *map; char filename[256]; int err; @@ -110,6 +113,9 @@ int main(int argc, char **argv) case 'T': kill_after_s = atoi(optarg); break; + case 'P': + max_pckt_size = atoi(optarg); + break; case 'S': xdp_flags |= XDP_FLAGS_SKB_MODE; break; @@ -150,12 +156,22 @@ int main(int argc, char **argv) if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd)) return 1; - map = bpf_map__next(NULL, obj); - if (!map) { - printf("finding a map in obj file failed\n"); + /* update pcktsz map */ + if (max_pckt_size) { + map_fd = bpf_object__find_map_fd_by_name(obj, "pcktsz"); + if (!map_fd) { + printf("finding a pcktsz map in obj file failed\n"); + return 1; + } + bpf_map_update_elem(map_fd, &key, &max_pckt_size, BPF_ANY); + } + + /* fetch icmpcnt map */ + map_fd = bpf_object__find_map_fd_by_name(obj, "icmpcnt"); + if (!map_fd) { + printf("finding a icmpcnt map in obj file failed\n"); return 1; } - map_fd = bpf_map__fd(map); if (!prog_fd) { printf("load_bpf_file: %s\n", strerror(errno)); -- 2.20.1