--- /dev/null
+/*
+ * Minimal BPF debugger
+ *
+ * Minimal BPF debugger that mimics the kernel's engine (w/o extensions)
+ * and allows for single stepping through selected packets from a pcap
+ * with a provided user filter in order to facilitate verification of a
+ * BPF program. Besides others, this is useful to verify BPF programs
+ * before attaching to a live system, and can be used in socket filters,
+ * cls_bpf, xt_bpf, team driver and e.g. PTP code; in particular when a
+ * single more complex BPF program is being used. Reasons for a more
+ * complex BPF program are likely primarily to optimize execution time
+ * for making a verdict when multiple simple BPF programs are combined
+ * into one in order to prevent parsing same headers multiple times.
+ *
+ * More on how to debug BPF opcodes see Documentation/networking/filter.txt
+ * which is the main document on BPF. Mini howto for getting started:
+ *
+ * 1) `./bpf_dbg` to enter the shell (shell cmds denoted with '>'):
+ * 2) > load bpf 6,40 0 0 12,21 0 3 20... (output from `bpf_asm` or
+ * `tcpdump -iem1 -ddd port 22 | tr '\n' ','` to load as filter)
+ * 3) > load pcap foo.pcap
+ * 4) > run <n>/disassemble/dump/quit (self-explanatory)
+ * 5) > breakpoint 2 (sets bp at loaded BPF insns 2, do `run` then;
+ * multiple bps can be set, of course, a call to `breakpoint`
+ * w/o args shows currently loaded bps, `breakpoint reset` for
+ * resetting all breakpoints)
+ * 6) > select 3 (`run` etc will start from the 3rd packet in the pcap)
+ * 7) > step [-<n>, +<n>] (performs single stepping through the BPF)
+ *
+ * Copyright 2013 Daniel Borkmann <borkmann@redhat.com>
+ * Licensed under the GNU General Public License, version 2.0 (GPLv2)
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <stdbool.h>
+#include <stdarg.h>
+#include <setjmp.h>
+#include <linux/filter.h>
+#include <linux/if_packet.h>
+#include <readline/readline.h>
+#include <readline/history.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <signal.h>
+#include <arpa/inet.h>
+#include <net/ethernet.h>
+
+#define TCPDUMP_MAGIC 0xa1b2c3d4
+
+#define BPF_LDX_B (BPF_LDX | BPF_B)
+#define BPF_LDX_W (BPF_LDX | BPF_W)
+#define BPF_JMP_JA (BPF_JMP | BPF_JA)
+#define BPF_JMP_JEQ (BPF_JMP | BPF_JEQ)
+#define BPF_JMP_JGT (BPF_JMP | BPF_JGT)
+#define BPF_JMP_JGE (BPF_JMP | BPF_JGE)
+#define BPF_JMP_JSET (BPF_JMP | BPF_JSET)
+#define BPF_ALU_ADD (BPF_ALU | BPF_ADD)
+#define BPF_ALU_SUB (BPF_ALU | BPF_SUB)
+#define BPF_ALU_MUL (BPF_ALU | BPF_MUL)
+#define BPF_ALU_DIV (BPF_ALU | BPF_DIV)
+#define BPF_ALU_MOD (BPF_ALU | BPF_MOD)
+#define BPF_ALU_NEG (BPF_ALU | BPF_NEG)
+#define BPF_ALU_AND (BPF_ALU | BPF_AND)
+#define BPF_ALU_OR (BPF_ALU | BPF_OR)
+#define BPF_ALU_XOR (BPF_ALU | BPF_XOR)
+#define BPF_ALU_LSH (BPF_ALU | BPF_LSH)
+#define BPF_ALU_RSH (BPF_ALU | BPF_RSH)
+#define BPF_MISC_TAX (BPF_MISC | BPF_TAX)
+#define BPF_MISC_TXA (BPF_MISC | BPF_TXA)
+#define BPF_LD_B (BPF_LD | BPF_B)
+#define BPF_LD_H (BPF_LD | BPF_H)
+#define BPF_LD_W (BPF_LD | BPF_W)
+
+#ifndef array_size
+# define array_size(x) (sizeof(x) / sizeof((x)[0]))
+#endif
+
+#ifndef __check_format_printf
+# define __check_format_printf(pos_fmtstr, pos_fmtargs) \
+ __attribute__ ((format (printf, (pos_fmtstr), (pos_fmtargs))))
+#endif
+
+enum {
+ CMD_OK,
+ CMD_ERR,
+ CMD_EX,
+};
+
+struct shell_cmd {
+ const char *name;
+ int (*func)(char *args);
+};
+
+struct pcap_filehdr {
+ uint32_t magic;
+ uint16_t version_major;
+ uint16_t version_minor;
+ int32_t thiszone;
+ uint32_t sigfigs;
+ uint32_t snaplen;
+ uint32_t linktype;
+};
+
+struct pcap_timeval {
+ int32_t tv_sec;
+ int32_t tv_usec;
+};
+
+struct pcap_pkthdr {
+ struct pcap_timeval ts;
+ uint32_t caplen;
+ uint32_t len;
+};
+
+struct bpf_regs {
+ uint32_t A;
+ uint32_t X;
+ uint32_t M[BPF_MEMWORDS];
+ uint32_t R;
+ bool Rs;
+ uint16_t Pc;
+};
+
+static struct sock_filter bpf_image[BPF_MAXINSNS + 1];
+static unsigned int bpf_prog_len = 0;
+
+static int bpf_breakpoints[64];
+static struct bpf_regs bpf_regs[BPF_MAXINSNS + 1];
+static struct bpf_regs bpf_curr;
+static unsigned int bpf_regs_len = 0;
+
+static int pcap_fd = -1;
+static unsigned int pcap_packet = 0;
+static size_t pcap_map_size = 0;
+static char *pcap_ptr_va_start, *pcap_ptr_va_curr;
+
+static const char * const op_table[] = {
+ [BPF_ST] = "st",
+ [BPF_STX] = "stx",
+ [BPF_LD_B] = "ldb",
+ [BPF_LD_H] = "ldh",
+ [BPF_LD_W] = "ld",
+ [BPF_LDX] = "ldx",
+ [BPF_LDX_B] = "ldxb",
+ [BPF_JMP_JA] = "ja",
+ [BPF_JMP_JEQ] = "jeq",
+ [BPF_JMP_JGT] = "jgt",
+ [BPF_JMP_JGE] = "jge",
+ [BPF_JMP_JSET] = "jset",
+ [BPF_ALU_ADD] = "add",
+ [BPF_ALU_SUB] = "sub",
+ [BPF_ALU_MUL] = "mul",
+ [BPF_ALU_DIV] = "div",
+ [BPF_ALU_MOD] = "mod",
+ [BPF_ALU_NEG] = "neg",
+ [BPF_ALU_AND] = "and",
+ [BPF_ALU_OR] = "or",
+ [BPF_ALU_XOR] = "xor",
+ [BPF_ALU_LSH] = "lsh",
+ [BPF_ALU_RSH] = "rsh",
+ [BPF_MISC_TAX] = "tax",
+ [BPF_MISC_TXA] = "txa",
+ [BPF_RET] = "ret",
+};
+
+static __check_format_printf(1, 2) int rl_printf(const char *fmt, ...)
+{
+ int ret;
+ va_list vl;
+
+ va_start(vl, fmt);
+ ret = vfprintf(rl_outstream, fmt, vl);
+ va_end(vl);
+
+ return ret;
+}
+
+static int matches(const char *cmd, const char *pattern)
+{
+ int len = strlen(cmd);
+
+ if (len > strlen(pattern))
+ return -1;
+
+ return memcmp(pattern, cmd, len);
+}
+
+static void hex_dump(const uint8_t *buf, size_t len)
+{
+ int i;
+
+ rl_printf("%3u: ", 0);
+ for (i = 0; i < len; i++) {
+ if (i && !(i % 16))
+ rl_printf("\n%3u: ", i);
+ rl_printf("%02x ", buf[i]);
+ }
+ rl_printf("\n");
+}
+
+static bool bpf_prog_loaded(void)
+{
+ if (bpf_prog_len == 0)
+ rl_printf("no bpf program loaded!\n");
+
+ return bpf_prog_len > 0;
+}
+
+static void bpf_disasm(const struct sock_filter f, unsigned int i)
+{
+ const char *op, *fmt;
+ int val = f.k;
+ char buf[256];
+
+ switch (f.code) {
+ case BPF_RET | BPF_K:
+ op = op_table[BPF_RET];
+ fmt = "#%#x";
+ break;
+ case BPF_RET | BPF_A:
+ op = op_table[BPF_RET];
+ fmt = "a";
+ break;
+ case BPF_RET | BPF_X:
+ op = op_table[BPF_RET];
+ fmt = "x";
+ break;
+ case BPF_MISC_TAX:
+ op = op_table[BPF_MISC_TAX];
+ fmt = "";
+ break;
+ case BPF_MISC_TXA:
+ op = op_table[BPF_MISC_TXA];
+ fmt = "";
+ break;
+ case BPF_ST:
+ op = op_table[BPF_ST];
+ fmt = "M[%d]";
+ break;
+ case BPF_STX:
+ op = op_table[BPF_STX];
+ fmt = "M[%d]";
+ break;
+ case BPF_LD_W | BPF_ABS:
+ op = op_table[BPF_LD_W];
+ fmt = "[%d]";
+ break;
+ case BPF_LD_H | BPF_ABS:
+ op = op_table[BPF_LD_H];
+ fmt = "[%d]";
+ break;
+ case BPF_LD_B | BPF_ABS:
+ op = op_table[BPF_LD_B];
+ fmt = "[%d]";
+ break;
+ case BPF_LD_W | BPF_LEN:
+ op = op_table[BPF_LD_W];
+ fmt = "#len";
+ break;
+ case BPF_LD_W | BPF_IND:
+ op = op_table[BPF_LD_W];
+ fmt = "[x+%d]";
+ break;
+ case BPF_LD_H | BPF_IND:
+ op = op_table[BPF_LD_H];
+ fmt = "[x+%d]";
+ break;
+ case BPF_LD_B | BPF_IND:
+ op = op_table[BPF_LD_B];
+ fmt = "[x+%d]";
+ break;
+ case BPF_LD | BPF_IMM:
+ op = op_table[BPF_LD_W];
+ fmt = "#%#x";
+ break;
+ case BPF_LDX | BPF_IMM:
+ op = op_table[BPF_LDX];
+ fmt = "#%#x";
+ break;
+ case BPF_LDX_B | BPF_MSH:
+ op = op_table[BPF_LDX_B];
+ fmt = "4*([%d]&0xf)";
+ break;
+ case BPF_LD | BPF_MEM:
+ op = op_table[BPF_LD_W];
+ fmt = "M[%d]";
+ break;
+ case BPF_LDX | BPF_MEM:
+ op = op_table[BPF_LDX];
+ fmt = "M[%d]";
+ break;
+ case BPF_JMP_JA:
+ op = op_table[BPF_JMP_JA];
+ fmt = "%d";
+ val = i + 1 + f.k;
+ break;
+ case BPF_JMP_JGT | BPF_X:
+ op = op_table[BPF_JMP_JGT];
+ fmt = "x";
+ break;
+ case BPF_JMP_JGT | BPF_K:
+ op = op_table[BPF_JMP_JGT];
+ fmt = "#%#x";
+ break;
+ case BPF_JMP_JGE | BPF_X:
+ op = op_table[BPF_JMP_JGE];
+ fmt = "x";
+ break;
+ case BPF_JMP_JGE | BPF_K:
+ op = op_table[BPF_JMP_JGE];
+ fmt = "#%#x";
+ break;
+ case BPF_JMP_JEQ | BPF_X:
+ op = op_table[BPF_JMP_JEQ];
+ fmt = "x";
+ break;
+ case BPF_JMP_JEQ | BPF_K:
+ op = op_table[BPF_JMP_JEQ];
+ fmt = "#%#x";
+ break;
+ case BPF_JMP_JSET | BPF_X:
+ op = op_table[BPF_JMP_JSET];
+ fmt = "x";
+ break;
+ case BPF_JMP_JSET | BPF_K:
+ op = op_table[BPF_JMP_JSET];
+ fmt = "#%#x";
+ break;
+ case BPF_ALU_NEG:
+ op = op_table[BPF_ALU_NEG];
+ fmt = "";
+ break;
+ case BPF_ALU_LSH | BPF_X:
+ op = op_table[BPF_ALU_LSH];
+ fmt = "x";
+ break;
+ case BPF_ALU_LSH | BPF_K:
+ op = op_table[BPF_ALU_LSH];
+ fmt = "#%d";
+ break;
+ case BPF_ALU_RSH | BPF_X:
+ op = op_table[BPF_ALU_RSH];
+ fmt = "x";
+ break;
+ case BPF_ALU_RSH | BPF_K:
+ op = op_table[BPF_ALU_RSH];
+ fmt = "#%d";
+ break;
+ case BPF_ALU_ADD | BPF_X:
+ op = op_table[BPF_ALU_ADD];
+ fmt = "x";
+ break;
+ case BPF_ALU_ADD | BPF_K:
+ op = op_table[BPF_ALU_ADD];
+ fmt = "#%d";
+ break;
+ case BPF_ALU_SUB | BPF_X:
+ op = op_table[BPF_ALU_SUB];
+ fmt = "x";
+ break;
+ case BPF_ALU_SUB | BPF_K:
+ op = op_table[BPF_ALU_SUB];
+ fmt = "#%d";
+ break;
+ case BPF_ALU_MUL | BPF_X:
+ op = op_table[BPF_ALU_MUL];
+ fmt = "x";
+ break;
+ case BPF_ALU_MUL | BPF_K:
+ op = op_table[BPF_ALU_MUL];
+ fmt = "#%d";
+ break;
+ case BPF_ALU_DIV | BPF_X:
+ op = op_table[BPF_ALU_DIV];
+ fmt = "x";
+ break;
+ case BPF_ALU_DIV | BPF_K:
+ op = op_table[BPF_ALU_DIV];
+ fmt = "#%d";
+ break;
+ case BPF_ALU_MOD | BPF_X:
+ op = op_table[BPF_ALU_MOD];
+ fmt = "x";
+ break;
+ case BPF_ALU_MOD | BPF_K:
+ op = op_table[BPF_ALU_MOD];
+ fmt = "#%d";
+ break;
+ case BPF_ALU_AND | BPF_X:
+ op = op_table[BPF_ALU_AND];
+ fmt = "x";
+ break;
+ case BPF_ALU_AND | BPF_K:
+ op = op_table[BPF_ALU_AND];
+ fmt = "#%#x";
+ break;
+ case BPF_ALU_OR | BPF_X:
+ op = op_table[BPF_ALU_OR];
+ fmt = "x";
+ break;
+ case BPF_ALU_OR | BPF_K:
+ op = op_table[BPF_ALU_OR];
+ fmt = "#%#x";
+ break;
+ case BPF_ALU_XOR | BPF_X:
+ op = op_table[BPF_ALU_XOR];
+ fmt = "x";
+ break;
+ case BPF_ALU_XOR | BPF_K:
+ op = op_table[BPF_ALU_XOR];
+ fmt = "#%#x";
+ break;
+ default:
+ op = "nosup";
+ fmt = "%#x";
+ val = f.code;
+ break;
+ }
+
+ memset(buf, 0, sizeof(buf));
+ snprintf(buf, sizeof(buf), fmt, val);
+ buf[sizeof(buf) - 1] = 0;
+
+ if ((BPF_CLASS(f.code) == BPF_JMP && BPF_OP(f.code) != BPF_JA))
+ rl_printf("l%d:\t%s %s, l%d, l%d\n", i, op, buf,
+ i + 1 + f.jt, i + 1 + f.jf);
+ else
+ rl_printf("l%d:\t%s %s\n", i, op, buf);
+}
+
+static void bpf_dump_curr(struct bpf_regs *r, struct sock_filter *f)
+{
+ int i, m = 0;
+
+ rl_printf("pc: [%u]\n", r->Pc);
+ rl_printf("code: [%u] jt[%u] jf[%u] k[%u]\n",
+ f->code, f->jt, f->jf, f->k);
+ rl_printf("curr: ");
+ bpf_disasm(*f, r->Pc);
+
+ if (f->jt || f->jf) {
+ rl_printf("jt: ");
+ bpf_disasm(*(f + f->jt + 1), r->Pc + f->jt + 1);
+ rl_printf("jf: ");
+ bpf_disasm(*(f + f->jf + 1), r->Pc + f->jf + 1);
+ }
+
+ rl_printf("A: [%#08x][%u]\n", r->A, r->A);
+ rl_printf("X: [%#08x][%u]\n", r->X, r->X);
+ if (r->Rs)
+ rl_printf("ret: [%#08x][%u]!\n", r->R, r->R);
+
+ for (i = 0; i < BPF_MEMWORDS; i++) {
+ if (r->M[i]) {
+ m++;
+ rl_printf("M[%d]: [%#08x][%u]\n", i, r->M[i], r->M[i]);
+ }
+ }
+ if (m == 0)
+ rl_printf("M[0,%d]: [%#08x][%u]\n", BPF_MEMWORDS - 1, 0, 0);
+}
+
+static void bpf_dump_pkt(uint8_t *pkt, uint32_t pkt_caplen, uint32_t pkt_len)
+{
+ if (pkt_caplen != pkt_len)
+ rl_printf("cap: %u, len: %u\n", pkt_caplen, pkt_len);
+ else
+ rl_printf("len: %u\n", pkt_len);
+
+ hex_dump(pkt, pkt_caplen);
+}
+
+static void bpf_disasm_all(const struct sock_filter *f, unsigned int len)
+{
+ unsigned int i;
+
+ for (i = 0; i < len; i++)
+ bpf_disasm(f[i], i);
+}
+
+static void bpf_dump_all(const struct sock_filter *f, unsigned int len)
+{
+ unsigned int i;
+
+ rl_printf("/* { op, jt, jf, k }, */\n");
+ for (i = 0; i < len; i++)
+ rl_printf("{ %#04x, %2u, %2u, %#010x },\n",
+ f[i].code, f[i].jt, f[i].jf, f[i].k);
+}
+
+static bool bpf_runnable(struct sock_filter *f, unsigned int len)
+{
+ int sock, ret, i;
+ struct sock_fprog bpf = {
+ .filter = f,
+ .len = len,
+ };
+
+ sock = socket(AF_INET, SOCK_DGRAM, 0);
+ if (sock < 0) {
+ rl_printf("cannot open socket!\n");
+ return false;
+ }
+ ret = setsockopt(sock, SOL_SOCKET, SO_ATTACH_FILTER, &bpf, sizeof(bpf));
+ close(sock);
+ if (ret < 0) {
+ rl_printf("program not allowed to run by kernel!\n");
+ return false;
+ }
+ for (i = 0; i < len; i++) {
+ if (BPF_CLASS(f[i].code) == BPF_LD &&
+ f[i].k > SKF_AD_OFF) {
+ rl_printf("extensions currently not supported!\n");
+ return false;
+ }
+ }
+
+ return true;
+}
+
+static void bpf_reset_breakpoints(void)
+{
+ int i;
+
+ for (i = 0; i < array_size(bpf_breakpoints); i++)
+ bpf_breakpoints[i] = -1;
+}
+
+static void bpf_set_breakpoints(unsigned int where)
+{
+ int i;
+ bool set = false;
+
+ for (i = 0; i < array_size(bpf_breakpoints); i++) {
+ if (bpf_breakpoints[i] == (int) where) {
+ rl_printf("breakpoint already set!\n");
+ set = true;
+ break;
+ }
+
+ if (bpf_breakpoints[i] == -1 && set == false) {
+ bpf_breakpoints[i] = where;
+ set = true;
+ }
+ }
+
+ if (!set)
+ rl_printf("too many breakpoints set, reset first!\n");
+}
+
+static void bpf_dump_breakpoints(void)
+{
+ int i;
+
+ rl_printf("breakpoints: ");
+
+ for (i = 0; i < array_size(bpf_breakpoints); i++) {
+ if (bpf_breakpoints[i] < 0)
+ continue;
+ rl_printf("%d ", bpf_breakpoints[i]);
+ }
+
+ rl_printf("\n");
+}
+
+static void bpf_reset(void)
+{
+ bpf_regs_len = 0;
+
+ memset(bpf_regs, 0, sizeof(bpf_regs));
+ memset(&bpf_curr, 0, sizeof(bpf_curr));
+}
+
+static void bpf_safe_regs(void)
+{
+ memcpy(&bpf_regs[bpf_regs_len++], &bpf_curr, sizeof(bpf_curr));
+}
+
+static bool bpf_restore_regs(int off)
+{
+ unsigned int index = bpf_regs_len - 1 + off;
+
+ if (index == 0) {
+ bpf_reset();
+ return true;
+ } else if (index < bpf_regs_len) {
+ memcpy(&bpf_curr, &bpf_regs[index], sizeof(bpf_curr));
+ bpf_regs_len = index;
+ return true;
+ } else {
+ rl_printf("reached bottom of register history stack!\n");
+ return false;
+ }
+}
+
+static uint32_t extract_u32(uint8_t *pkt, uint32_t off)
+{
+ uint32_t r;
+
+ memcpy(&r, &pkt[off], sizeof(r));
+
+ return ntohl(r);
+}
+
+static uint16_t extract_u16(uint8_t *pkt, uint32_t off)
+{
+ uint16_t r;
+
+ memcpy(&r, &pkt[off], sizeof(r));
+
+ return ntohs(r);
+}
+
+static uint8_t extract_u8(uint8_t *pkt, uint32_t off)
+{
+ return pkt[off];
+}
+
+static void set_return(struct bpf_regs *r)
+{
+ r->R = 0;
+ r->Rs = true;
+}
+
+static void bpf_single_step(struct bpf_regs *r, struct sock_filter *f,
+ uint8_t *pkt, uint32_t pkt_caplen,
+ uint32_t pkt_len)
+{
+ uint32_t K = f->k;
+ int d;
+
+ switch (f->code) {
+ case BPF_RET | BPF_K:
+ r->R = K;
+ r->Rs = true;
+ break;
+ case BPF_RET | BPF_A:
+ r->R = r->A;
+ r->Rs = true;
+ break;
+ case BPF_RET | BPF_X:
+ r->R = r->X;
+ r->Rs = true;
+ break;
+ case BPF_MISC_TAX:
+ r->X = r->A;
+ break;
+ case BPF_MISC_TXA:
+ r->A = r->X;
+ break;
+ case BPF_ST:
+ r->M[K] = r->A;
+ break;
+ case BPF_STX:
+ r->M[K] = r->X;
+ break;
+ case BPF_LD_W | BPF_ABS:
+ d = pkt_caplen - K;
+ if (d >= sizeof(uint32_t))
+ r->A = extract_u32(pkt, K);
+ else
+ set_return(r);
+ break;
+ case BPF_LD_H | BPF_ABS:
+ d = pkt_caplen - K;
+ if (d >= sizeof(uint16_t))
+ r->A = extract_u16(pkt, K);
+ else
+ set_return(r);
+ break;
+ case BPF_LD_B | BPF_ABS:
+ d = pkt_caplen - K;
+ if (d >= sizeof(uint8_t))
+ r->A = extract_u8(pkt, K);
+ else
+ set_return(r);
+ break;
+ case BPF_LD_W | BPF_IND:
+ d = pkt_caplen - (r->X + K);
+ if (d >= sizeof(uint32_t))
+ r->A = extract_u32(pkt, r->X + K);
+ break;
+ case BPF_LD_H | BPF_IND:
+ d = pkt_caplen - (r->X + K);
+ if (d >= sizeof(uint16_t))
+ r->A = extract_u16(pkt, r->X + K);
+ else
+ set_return(r);
+ break;
+ case BPF_LD_B | BPF_IND:
+ d = pkt_caplen - (r->X + K);
+ if (d >= sizeof(uint8_t))
+ r->A = extract_u8(pkt, r->X + K);
+ else
+ set_return(r);
+ break;
+ case BPF_LDX_B | BPF_MSH:
+ d = pkt_caplen - K;
+ if (d >= sizeof(uint8_t)) {
+ r->X = extract_u8(pkt, K);
+ r->X = (r->X & 0xf) << 2;
+ } else
+ set_return(r);
+ break;
+ case BPF_LD_W | BPF_LEN:
+ r->A = pkt_len;
+ break;
+ case BPF_LDX_W | BPF_LEN:
+ r->A = pkt_len;
+ break;
+ case BPF_LD | BPF_IMM:
+ r->A = K;
+ break;
+ case BPF_LDX | BPF_IMM:
+ r->X = K;
+ break;
+ case BPF_LD | BPF_MEM:
+ r->A = r->M[K];
+ break;
+ case BPF_LDX | BPF_MEM:
+ r->X = r->M[K];
+ break;
+ case BPF_JMP_JA:
+ r->Pc += K;
+ break;
+ case BPF_JMP_JGT | BPF_X:
+ r->Pc += r->A > r->X ? f->jt : f->jf;
+ break;
+ case BPF_JMP_JGT | BPF_K:
+ r->Pc += r->A > K ? f->jt : f->jf;
+ break;
+ case BPF_JMP_JGE | BPF_X:
+ r->Pc += r->A >= r->X ? f->jt : f->jf;
+ break;
+ case BPF_JMP_JGE | BPF_K:
+ r->Pc += r->A >= K ? f->jt : f->jf;
+ break;
+ case BPF_JMP_JEQ | BPF_X:
+ r->Pc += r->A == r->X ? f->jt : f->jf;
+ break;
+ case BPF_JMP_JEQ | BPF_K:
+ r->Pc += r->A == K ? f->jt : f->jf;
+ break;
+ case BPF_JMP_JSET | BPF_X:
+ r->Pc += r->A & r->X ? f->jt : f->jf;
+ break;
+ case BPF_JMP_JSET | BPF_K:
+ r->Pc += r->A & K ? f->jt : f->jf;
+ break;
+ case BPF_ALU_NEG:
+ r->A = -r->A;
+ break;
+ case BPF_ALU_LSH | BPF_X:
+ r->A <<= r->X;
+ break;
+ case BPF_ALU_LSH | BPF_K:
+ r->A <<= K;
+ break;
+ case BPF_ALU_RSH | BPF_X:
+ r->A >>= r->X;
+ break;
+ case BPF_ALU_RSH | BPF_K:
+ r->A >>= K;
+ break;
+ case BPF_ALU_ADD | BPF_X:
+ r->A += r->X;
+ break;
+ case BPF_ALU_ADD | BPF_K:
+ r->A += K;
+ break;
+ case BPF_ALU_SUB | BPF_X:
+ r->A -= r->X;
+ break;
+ case BPF_ALU_SUB | BPF_K:
+ r->A -= K;
+ break;
+ case BPF_ALU_MUL | BPF_X:
+ r->A *= r->X;
+ break;
+ case BPF_ALU_MUL | BPF_K:
+ r->A *= K;
+ break;
+ case BPF_ALU_DIV | BPF_X:
+ case BPF_ALU_MOD | BPF_X:
+ if (r->X == 0) {
+ set_return(r);
+ break;
+ }
+ goto do_div;
+ case BPF_ALU_DIV | BPF_K:
+ case BPF_ALU_MOD | BPF_K:
+ if (K == 0) {
+ set_return(r);
+ break;
+ }
+do_div:
+ switch (f->code) {
+ case BPF_ALU_DIV | BPF_X:
+ r->A /= r->X;
+ break;
+ case BPF_ALU_DIV | BPF_K:
+ r->A /= K;
+ break;
+ case BPF_ALU_MOD | BPF_X:
+ r->A %= r->X;
+ break;
+ case BPF_ALU_MOD | BPF_K:
+ r->A %= K;
+ break;
+ }
+ break;
+ case BPF_ALU_AND | BPF_X:
+ r->A &= r->X;
+ break;
+ case BPF_ALU_AND | BPF_K:
+ r->A &= K;
+ break;
+ case BPF_ALU_OR | BPF_X:
+ r->A |= r->X;
+ break;
+ case BPF_ALU_OR | BPF_K:
+ r->A |= K;
+ break;
+ case BPF_ALU_XOR | BPF_X:
+ r->A ^= r->X;
+ break;
+ case BPF_ALU_XOR | BPF_K:
+ r->A ^= K;
+ break;
+ }
+}
+
+static bool bpf_pc_has_breakpoint(uint16_t pc)
+{
+ int i;
+
+ for (i = 0; i < array_size(bpf_breakpoints); i++) {
+ if (bpf_breakpoints[i] < 0)
+ continue;
+ if (bpf_breakpoints[i] == pc)
+ return true;
+ }
+
+ return false;
+}
+
+static bool bpf_handle_breakpoint(struct bpf_regs *r, struct sock_filter *f,
+ uint8_t *pkt, uint32_t pkt_caplen,
+ uint32_t pkt_len)
+{
+ rl_printf("-- register dump --\n");
+ bpf_dump_curr(r, &f[r->Pc]);
+ rl_printf("-- packet dump --\n");
+ bpf_dump_pkt(pkt, pkt_caplen, pkt_len);
+ rl_printf("(breakpoint)\n");
+ return true;
+}
+
+static int bpf_run_all(struct sock_filter *f, uint16_t bpf_len, uint8_t *pkt,
+ uint32_t pkt_caplen, uint32_t pkt_len)
+{
+ bool stop = false;
+
+ while (bpf_curr.Rs == false && stop == false) {
+ bpf_safe_regs();
+
+ if (bpf_pc_has_breakpoint(bpf_curr.Pc))
+ stop = bpf_handle_breakpoint(&bpf_curr, f, pkt,
+ pkt_caplen, pkt_len);
+
+ bpf_single_step(&bpf_curr, &f[bpf_curr.Pc], pkt, pkt_caplen,
+ pkt_len);
+ bpf_curr.Pc++;
+ }
+
+ return stop ? -1 : bpf_curr.R;
+}
+
+static int bpf_run_stepping(struct sock_filter *f, uint16_t bpf_len,
+ uint8_t *pkt, uint32_t pkt_caplen,
+ uint32_t pkt_len, int next)
+{
+ bool stop = false;
+ int i = 1;
+
+ while (bpf_curr.Rs == false && stop == false) {
+ bpf_safe_regs();
+
+ if (i++ == next)
+ stop = bpf_handle_breakpoint(&bpf_curr, f, pkt,
+ pkt_caplen, pkt_len);
+
+ bpf_single_step(&bpf_curr, &f[bpf_curr.Pc], pkt, pkt_caplen,
+ pkt_len);
+ bpf_curr.Pc++;
+ }
+
+ return stop ? -1 : bpf_curr.R;
+}
+
+static bool pcap_loaded(void)
+{
+ if (pcap_fd < 0)
+ rl_printf("no pcap file loaded!\n");
+
+ return pcap_fd >= 0;
+}
+
+static struct pcap_pkthdr *pcap_curr_pkt(void)
+{
+ return (void *) pcap_ptr_va_curr;
+}
+
+static bool pcap_next_pkt(void)
+{
+ struct pcap_pkthdr *hdr = pcap_curr_pkt();
+
+ if (pcap_ptr_va_curr + sizeof(*hdr) -
+ pcap_ptr_va_start >= pcap_map_size)
+ return false;
+ if (hdr->caplen == 0 || hdr->len == 0 || hdr->caplen > hdr->len)
+ return false;
+ if (pcap_ptr_va_curr + sizeof(*hdr) + hdr->caplen -
+ pcap_ptr_va_start >= pcap_map_size)
+ return false;
+
+ pcap_ptr_va_curr += (sizeof(*hdr) + hdr->caplen);
+ return true;
+}
+
+static void pcap_reset_pkt(void)
+{
+ pcap_ptr_va_curr = pcap_ptr_va_start + sizeof(struct pcap_filehdr);
+}
+
+static int try_load_pcap(const char *file)
+{
+ struct pcap_filehdr *hdr;
+ struct stat sb;
+ int ret;
+
+ pcap_fd = open(file, O_RDONLY);
+ if (pcap_fd < 0) {
+ rl_printf("cannot open pcap [%s]!\n", strerror(errno));
+ return CMD_ERR;
+ }
+
+ ret = fstat(pcap_fd, &sb);
+ if (ret < 0) {
+ rl_printf("cannot fstat pcap file!\n");
+ return CMD_ERR;
+ }
+
+ if (!S_ISREG(sb.st_mode)) {
+ rl_printf("not a regular pcap file, duh!\n");
+ return CMD_ERR;
+ }
+
+ pcap_map_size = sb.st_size;
+ if (pcap_map_size <= sizeof(struct pcap_filehdr)) {
+ rl_printf("pcap file too small!\n");
+ return CMD_ERR;
+ }
+
+ pcap_ptr_va_start = mmap(NULL, pcap_map_size, PROT_READ,
+ MAP_SHARED | MAP_LOCKED, pcap_fd, 0);
+ if (pcap_ptr_va_start == MAP_FAILED) {
+ rl_printf("mmap of file failed!");
+ return CMD_ERR;
+ }
+
+ hdr = (void *) pcap_ptr_va_start;
+ if (hdr->magic != TCPDUMP_MAGIC) {
+ rl_printf("wrong pcap magic!\n");
+ return CMD_ERR;
+ }
+
+ pcap_reset_pkt();
+
+ return CMD_OK;
+
+}
+
+static void try_close_pcap(void)
+{
+ if (pcap_fd >= 0) {
+ munmap(pcap_ptr_va_start, pcap_map_size);
+ close(pcap_fd);
+
+ pcap_ptr_va_start = pcap_ptr_va_curr = NULL;
+ pcap_map_size = 0;
+ pcap_packet = 0;
+ pcap_fd = -1;
+ }
+}
+
+static int cmd_load_bpf(char *bpf_string)
+{
+ char sp, *token, separator = ',';
+ unsigned short bpf_len, i = 0;
+ struct sock_filter tmp;
+
+ bpf_prog_len = 0;
+ memset(bpf_image, 0, sizeof(bpf_image));
+
+ if (sscanf(bpf_string, "%hu%c", &bpf_len, &sp) != 2 ||
+ sp != separator || bpf_len > BPF_MAXINSNS || bpf_len == 0) {
+ rl_printf("syntax error in head length encoding!\n");
+ return CMD_ERR;
+ }
+
+ token = bpf_string;
+ while ((token = strchr(token, separator)) && (++token)[0]) {
+ if (i >= bpf_len) {
+ rl_printf("program exceeds encoded length!\n");
+ return CMD_ERR;
+ }
+
+ if (sscanf(token, "%hu %hhu %hhu %u,",
+ &tmp.code, &tmp.jt, &tmp.jf, &tmp.k) != 4) {
+ rl_printf("syntax error at instruction %d!\n", i);
+ return CMD_ERR;
+ }
+
+ bpf_image[i].code = tmp.code;
+ bpf_image[i].jt = tmp.jt;
+ bpf_image[i].jf = tmp.jf;
+ bpf_image[i].k = tmp.k;
+
+ i++;
+ }
+
+ if (i != bpf_len) {
+ rl_printf("syntax error exceeding encoded length!\n");
+ return CMD_ERR;
+ } else
+ bpf_prog_len = bpf_len;
+ if (!bpf_runnable(bpf_image, bpf_prog_len))
+ bpf_prog_len = 0;
+
+ return CMD_OK;
+}
+
+static int cmd_load_pcap(char *file)
+{
+ char *file_trim, *tmp;
+
+ file_trim = strtok_r(file, " ", &tmp);
+ if (file_trim == NULL)
+ return CMD_ERR;
+
+ try_close_pcap();
+
+ return try_load_pcap(file_trim);
+}
+
+static int cmd_load(char *arg)
+{
+ char *subcmd, *cont, *tmp = strdup(arg);
+ int ret = CMD_OK;
+
+ subcmd = strtok_r(tmp, " ", &cont);
+ if (subcmd == NULL)
+ goto out;
+ if (matches(subcmd, "bpf") == 0) {
+ bpf_reset();
+ bpf_reset_breakpoints();
+
+ ret = cmd_load_bpf(cont);
+ } else if (matches(subcmd, "pcap") == 0) {
+ ret = cmd_load_pcap(cont);
+ } else {
+out:
+ rl_printf("bpf <code>: load bpf code\n");
+ rl_printf("pcap <file>: load pcap file\n");
+ ret = CMD_ERR;
+ }
+
+ free(tmp);
+ return ret;
+}
+
+static int cmd_step(char *num)
+{
+ struct pcap_pkthdr *hdr;
+ int steps, ret;
+
+ if (!bpf_prog_loaded() || !pcap_loaded())
+ return CMD_ERR;
+
+ steps = strtol(num, NULL, 10);
+ if (steps == 0 || strlen(num) == 0)
+ steps = 1;
+ if (steps < 0) {
+ if (!bpf_restore_regs(steps))
+ return CMD_ERR;
+ steps = 1;
+ }
+
+ hdr = pcap_curr_pkt();
+ ret = bpf_run_stepping(bpf_image, bpf_prog_len,
+ (uint8_t *) hdr + sizeof(*hdr),
+ hdr->caplen, hdr->len, steps);
+ if (ret >= 0 || bpf_curr.Rs) {
+ bpf_reset();
+ if (!pcap_next_pkt()) {
+ rl_printf("(going back to first packet)\n");
+ pcap_reset_pkt();
+ } else {
+ rl_printf("(next packet)\n");
+ }
+ }
+
+ return CMD_OK;
+}
+
+static int cmd_select(char *num)
+{
+ unsigned int which, i;
+ bool have_next = true;
+
+ if (!pcap_loaded() || strlen(num) == 0)
+ return CMD_ERR;
+
+ which = strtoul(num, NULL, 10);
+ if (which == 0) {
+ rl_printf("packet count starts with 1, clamping!\n");
+ which = 1;
+ }
+
+ pcap_reset_pkt();
+ bpf_reset();
+
+ for (i = 0; i < which && (have_next = pcap_next_pkt()); i++)
+ /* noop */;
+ if (!have_next || pcap_curr_pkt() == NULL) {
+ rl_printf("no packet #%u available!\n", which);
+ pcap_reset_pkt();
+ return CMD_ERR;
+ }
+
+ return CMD_OK;
+}
+
+static int cmd_breakpoint(char *subcmd)
+{
+ if (!bpf_prog_loaded())
+ return CMD_ERR;
+ if (strlen(subcmd) == 0)
+ bpf_dump_breakpoints();
+ else if (matches(subcmd, "reset") == 0)
+ bpf_reset_breakpoints();
+ else {
+ unsigned int where = strtoul(subcmd, NULL, 10);
+
+ if (where < bpf_prog_len) {
+ bpf_set_breakpoints(where);
+ rl_printf("breakpoint at: ");
+ bpf_disasm(bpf_image[where], where);
+ }
+ }
+
+ return CMD_OK;
+}
+
+static int cmd_run(char *num)
+{
+ static uint32_t pass = 0, fail = 0;
+ bool has_limit = true;
+ int pkts = 0, i = 0;
+
+ if (!bpf_prog_loaded() || !pcap_loaded())
+ return CMD_ERR;
+
+ pkts = strtol(num, NULL, 10);
+ if (pkts == 0 || strlen(num) == 0)
+ has_limit = false;
+
+ do {
+ struct pcap_pkthdr *hdr = pcap_curr_pkt();
+ int ret = bpf_run_all(bpf_image, bpf_prog_len,
+ (uint8_t *) hdr + sizeof(*hdr),
+ hdr->caplen, hdr->len);
+ if (ret > 0)
+ pass++;
+ else if (ret == 0)
+ fail++;
+ else
+ return CMD_OK;
+ bpf_reset();
+ } while (pcap_next_pkt() && (!has_limit || (has_limit && ++i < pkts)));
+
+ rl_printf("bpf passes:%u fails:%u\n", pass, fail);
+
+ pcap_reset_pkt();
+ bpf_reset();
+
+ pass = fail = 0;
+ return CMD_OK;
+}
+
+static int cmd_disassemble(char *line_string)
+{
+ bool single_line = false;
+ unsigned long line;
+
+ if (!bpf_prog_loaded())
+ return CMD_ERR;
+ if (strlen(line_string) > 0 &&
+ (line = strtoul(line_string, NULL, 10)) < bpf_prog_len)
+ single_line = true;
+ if (single_line)
+ bpf_disasm(bpf_image[line], line);
+ else
+ bpf_disasm_all(bpf_image, bpf_prog_len);
+
+ return CMD_OK;
+}
+
+static int cmd_dump(char *dontcare)
+{
+ if (!bpf_prog_loaded())
+ return CMD_ERR;
+
+ bpf_dump_all(bpf_image, bpf_prog_len);
+
+ return CMD_OK;
+}
+
+static int cmd_quit(char *dontcare)
+{
+ return CMD_EX;
+}
+
+static const struct shell_cmd cmds[] = {
+ { .name = "load", .func = cmd_load },
+ { .name = "select", .func = cmd_select },
+ { .name = "step", .func = cmd_step },
+ { .name = "run", .func = cmd_run },
+ { .name = "breakpoint", .func = cmd_breakpoint },
+ { .name = "disassemble", .func = cmd_disassemble },
+ { .name = "dump", .func = cmd_dump },
+ { .name = "quit", .func = cmd_quit },
+};
+
+static int execf(char *arg)
+{
+ char *cmd, *cont, *tmp = strdup(arg);
+ int i, ret = 0, len;
+
+ cmd = strtok_r(tmp, " ", &cont);
+ if (cmd == NULL)
+ goto out;
+ len = strlen(cmd);
+ for (i = 0; i < array_size(cmds); i++) {
+ if (len != strlen(cmds[i].name))
+ continue;
+ if (strncmp(cmds[i].name, cmd, len) == 0) {
+ ret = cmds[i].func(cont);
+ break;
+ }
+ }
+out:
+ free(tmp);
+ return ret;
+}
+
+static char *shell_comp_gen(const char *buf, int state)
+{
+ static int list_index, len;
+
+ if (!state) {
+ list_index = 0;
+ len = strlen(buf);
+ }
+
+ for (; list_index < array_size(cmds); ) {
+ const char *name = cmds[list_index].name;
+
+ list_index++;
+ if (strncmp(name, buf, len) == 0)
+ return strdup(name);
+ }
+
+ return NULL;
+}
+
+static char **shell_completion(const char *buf, int start, int end)
+{
+ char **matches = NULL;
+
+ if (start == 0)
+ matches = rl_completion_matches(buf, shell_comp_gen);
+
+ return matches;
+}
+
+static void intr_shell(int sig)
+{
+ if (rl_end)
+ rl_kill_line(-1, 0);
+
+ rl_crlf();
+ rl_refresh_line(0, 0);
+ rl_free_line_state();
+}
+
+static void init_shell(FILE *fin, FILE *fout)
+{
+ char file[128];
+
+ snprintf(file, sizeof(file), "%s/.bpf_dbg_history", getenv("HOME"));
+ read_history(file);
+
+ rl_instream = fin;
+ rl_outstream = fout;
+
+ rl_readline_name = "bpf_dbg";
+ rl_terminal_name = getenv("TERM");
+
+ rl_catch_signals = 0;
+ rl_catch_sigwinch = 1;
+
+ rl_attempted_completion_function = shell_completion;
+
+ rl_bind_key('\t', rl_complete);
+
+ rl_bind_key_in_map('\t', rl_complete, emacs_meta_keymap);
+ rl_bind_key_in_map('\033', rl_complete, emacs_meta_keymap);
+
+ snprintf(file, sizeof(file), "%s/.bpf_dbg_init", getenv("HOME"));
+ rl_read_init_file(file);
+
+ rl_prep_terminal(0);
+ rl_set_signals();
+
+ signal(SIGINT, intr_shell);
+}
+
+static void exit_shell(FILE *fin, FILE *fout)
+{
+ char file[128];
+
+ snprintf(file, sizeof(file), "%s/.bpf_dbg_history", getenv("HOME"));
+ write_history(file);
+
+ clear_history();
+ rl_deprep_terminal();
+
+ try_close_pcap();
+
+ if (fin != stdin)
+ fclose(fin);
+ if (fout != stdout)
+ fclose(fout);
+}
+
+static int run_shell_loop(FILE *fin, FILE *fout)
+{
+ char *buf;
+
+ init_shell(fin, fout);
+
+ while ((buf = readline("> ")) != NULL) {
+ int ret = execf(buf);
+ if (ret == CMD_EX)
+ break;
+ if (ret == CMD_OK && strlen(buf) > 0)
+ add_history(buf);
+
+ free(buf);
+ }
+
+ exit_shell(fin, fout);
+ return 0;
+}
+
+int main(int argc, char **argv)
+{
+ FILE *fin = NULL, *fout = NULL;
+
+ if (argc >= 2)
+ fin = fopen(argv[1], "r");
+ if (argc >= 3)
+ fout = fopen(argv[2], "w");
+
+ return run_shell_loop(fin ? : stdin, fout ? : stdout);
+}
Code Review / kvmfornfv.git / blobdiff