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0001 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
0002 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
0003  * Copyright (c) 2016 Facebook
0004  */
0005 
0006 #include <linux/bpf.h>
0007 
0008 #include "disasm.h"
0009 
0010 #define __BPF_FUNC_STR_FN(x) [BPF_FUNC_ ## x] = __stringify(bpf_ ## x)
0011 static const char * const func_id_str[] = {
0012     __BPF_FUNC_MAPPER(__BPF_FUNC_STR_FN)
0013 };
0014 #undef __BPF_FUNC_STR_FN
0015 
0016 static const char *__func_get_name(const struct bpf_insn_cbs *cbs,
0017                    const struct bpf_insn *insn,
0018                    char *buff, size_t len)
0019 {
0020     BUILD_BUG_ON(ARRAY_SIZE(func_id_str) != __BPF_FUNC_MAX_ID);
0021 
0022     if (!insn->src_reg &&
0023         insn->imm >= 0 && insn->imm < __BPF_FUNC_MAX_ID &&
0024         func_id_str[insn->imm])
0025         return func_id_str[insn->imm];
0026 
0027     if (cbs && cbs->cb_call) {
0028         const char *res;
0029 
0030         res = cbs->cb_call(cbs->private_data, insn);
0031         if (res)
0032             return res;
0033     }
0034 
0035     if (insn->src_reg == BPF_PSEUDO_CALL)
0036         snprintf(buff, len, "%+d", insn->imm);
0037     else if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL)
0038         snprintf(buff, len, "kernel-function");
0039 
0040     return buff;
0041 }
0042 
0043 static const char *__func_imm_name(const struct bpf_insn_cbs *cbs,
0044                    const struct bpf_insn *insn,
0045                    u64 full_imm, char *buff, size_t len)
0046 {
0047     if (cbs && cbs->cb_imm)
0048         return cbs->cb_imm(cbs->private_data, insn, full_imm);
0049 
0050     snprintf(buff, len, "0x%llx", (unsigned long long)full_imm);
0051     return buff;
0052 }
0053 
0054 const char *func_id_name(int id)
0055 {
0056     if (id >= 0 && id < __BPF_FUNC_MAX_ID && func_id_str[id])
0057         return func_id_str[id];
0058     else
0059         return "unknown";
0060 }
0061 
0062 const char *const bpf_class_string[8] = {
0063     [BPF_LD]    = "ld",
0064     [BPF_LDX]   = "ldx",
0065     [BPF_ST]    = "st",
0066     [BPF_STX]   = "stx",
0067     [BPF_ALU]   = "alu",
0068     [BPF_JMP]   = "jmp",
0069     [BPF_JMP32] = "jmp32",
0070     [BPF_ALU64] = "alu64",
0071 };
0072 
0073 const char *const bpf_alu_string[16] = {
0074     [BPF_ADD >> 4]  = "+=",
0075     [BPF_SUB >> 4]  = "-=",
0076     [BPF_MUL >> 4]  = "*=",
0077     [BPF_DIV >> 4]  = "/=",
0078     [BPF_OR  >> 4]  = "|=",
0079     [BPF_AND >> 4]  = "&=",
0080     [BPF_LSH >> 4]  = "<<=",
0081     [BPF_RSH >> 4]  = ">>=",
0082     [BPF_NEG >> 4]  = "neg",
0083     [BPF_MOD >> 4]  = "%=",
0084     [BPF_XOR >> 4]  = "^=",
0085     [BPF_MOV >> 4]  = "=",
0086     [BPF_ARSH >> 4] = "s>>=",
0087     [BPF_END >> 4]  = "endian",
0088 };
0089 
0090 static const char *const bpf_atomic_alu_string[16] = {
0091     [BPF_ADD >> 4]  = "add",
0092     [BPF_AND >> 4]  = "and",
0093     [BPF_OR >> 4]  = "or",
0094     [BPF_XOR >> 4]  = "xor",
0095 };
0096 
0097 static const char *const bpf_ldst_string[] = {
0098     [BPF_W >> 3]  = "u32",
0099     [BPF_H >> 3]  = "u16",
0100     [BPF_B >> 3]  = "u8",
0101     [BPF_DW >> 3] = "u64",
0102 };
0103 
0104 static const char *const bpf_jmp_string[16] = {
0105     [BPF_JA >> 4]   = "jmp",
0106     [BPF_JEQ >> 4]  = "==",
0107     [BPF_JGT >> 4]  = ">",
0108     [BPF_JLT >> 4]  = "<",
0109     [BPF_JGE >> 4]  = ">=",
0110     [BPF_JLE >> 4]  = "<=",
0111     [BPF_JSET >> 4] = "&",
0112     [BPF_JNE >> 4]  = "!=",
0113     [BPF_JSGT >> 4] = "s>",
0114     [BPF_JSLT >> 4] = "s<",
0115     [BPF_JSGE >> 4] = "s>=",
0116     [BPF_JSLE >> 4] = "s<=",
0117     [BPF_CALL >> 4] = "call",
0118     [BPF_EXIT >> 4] = "exit",
0119 };
0120 
0121 static void print_bpf_end_insn(bpf_insn_print_t verbose,
0122                    void *private_data,
0123                    const struct bpf_insn *insn)
0124 {
0125     verbose(private_data, "(%02x) r%d = %s%d r%d\n",
0126         insn->code, insn->dst_reg,
0127         BPF_SRC(insn->code) == BPF_TO_BE ? "be" : "le",
0128         insn->imm, insn->dst_reg);
0129 }
0130 
0131 void print_bpf_insn(const struct bpf_insn_cbs *cbs,
0132             const struct bpf_insn *insn,
0133             bool allow_ptr_leaks)
0134 {
0135     const bpf_insn_print_t verbose = cbs->cb_print;
0136     u8 class = BPF_CLASS(insn->code);
0137 
0138     if (class == BPF_ALU || class == BPF_ALU64) {
0139         if (BPF_OP(insn->code) == BPF_END) {
0140             if (class == BPF_ALU64)
0141                 verbose(cbs->private_data, "BUG_alu64_%02x\n", insn->code);
0142             else
0143                 print_bpf_end_insn(verbose, cbs->private_data, insn);
0144         } else if (BPF_OP(insn->code) == BPF_NEG) {
0145             verbose(cbs->private_data, "(%02x) %c%d = -%c%d\n",
0146                 insn->code, class == BPF_ALU ? 'w' : 'r',
0147                 insn->dst_reg, class == BPF_ALU ? 'w' : 'r',
0148                 insn->dst_reg);
0149         } else if (BPF_SRC(insn->code) == BPF_X) {
0150             verbose(cbs->private_data, "(%02x) %c%d %s %c%d\n",
0151                 insn->code, class == BPF_ALU ? 'w' : 'r',
0152                 insn->dst_reg,
0153                 bpf_alu_string[BPF_OP(insn->code) >> 4],
0154                 class == BPF_ALU ? 'w' : 'r',
0155                 insn->src_reg);
0156         } else {
0157             verbose(cbs->private_data, "(%02x) %c%d %s %d\n",
0158                 insn->code, class == BPF_ALU ? 'w' : 'r',
0159                 insn->dst_reg,
0160                 bpf_alu_string[BPF_OP(insn->code) >> 4],
0161                 insn->imm);
0162         }
0163     } else if (class == BPF_STX) {
0164         if (BPF_MODE(insn->code) == BPF_MEM)
0165             verbose(cbs->private_data, "(%02x) *(%s *)(r%d %+d) = r%d\n",
0166                 insn->code,
0167                 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
0168                 insn->dst_reg,
0169                 insn->off, insn->src_reg);
0170         else if (BPF_MODE(insn->code) == BPF_ATOMIC &&
0171              (insn->imm == BPF_ADD || insn->imm == BPF_AND ||
0172               insn->imm == BPF_OR || insn->imm == BPF_XOR)) {
0173             verbose(cbs->private_data, "(%02x) lock *(%s *)(r%d %+d) %s r%d\n",
0174                 insn->code,
0175                 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
0176                 insn->dst_reg, insn->off,
0177                 bpf_alu_string[BPF_OP(insn->imm) >> 4],
0178                 insn->src_reg);
0179         } else if (BPF_MODE(insn->code) == BPF_ATOMIC &&
0180                (insn->imm == (BPF_ADD | BPF_FETCH) ||
0181                 insn->imm == (BPF_AND | BPF_FETCH) ||
0182                 insn->imm == (BPF_OR | BPF_FETCH) ||
0183                 insn->imm == (BPF_XOR | BPF_FETCH))) {
0184             verbose(cbs->private_data, "(%02x) r%d = atomic%s_fetch_%s((%s *)(r%d %+d), r%d)\n",
0185                 insn->code, insn->src_reg,
0186                 BPF_SIZE(insn->code) == BPF_DW ? "64" : "",
0187                 bpf_atomic_alu_string[BPF_OP(insn->imm) >> 4],
0188                 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
0189                 insn->dst_reg, insn->off, insn->src_reg);
0190         } else if (BPF_MODE(insn->code) == BPF_ATOMIC &&
0191                insn->imm == BPF_CMPXCHG) {
0192             verbose(cbs->private_data, "(%02x) r0 = atomic%s_cmpxchg((%s *)(r%d %+d), r0, r%d)\n",
0193                 insn->code,
0194                 BPF_SIZE(insn->code) == BPF_DW ? "64" : "",
0195                 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
0196                 insn->dst_reg, insn->off,
0197                 insn->src_reg);
0198         } else if (BPF_MODE(insn->code) == BPF_ATOMIC &&
0199                insn->imm == BPF_XCHG) {
0200             verbose(cbs->private_data, "(%02x) r%d = atomic%s_xchg((%s *)(r%d %+d), r%d)\n",
0201                 insn->code, insn->src_reg,
0202                 BPF_SIZE(insn->code) == BPF_DW ? "64" : "",
0203                 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
0204                 insn->dst_reg, insn->off, insn->src_reg);
0205         } else {
0206             verbose(cbs->private_data, "BUG_%02x\n", insn->code);
0207         }
0208     } else if (class == BPF_ST) {
0209         if (BPF_MODE(insn->code) == BPF_MEM) {
0210             verbose(cbs->private_data, "(%02x) *(%s *)(r%d %+d) = %d\n",
0211                 insn->code,
0212                 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
0213                 insn->dst_reg,
0214                 insn->off, insn->imm);
0215         } else if (BPF_MODE(insn->code) == 0xc0 /* BPF_NOSPEC, no UAPI */) {
0216             verbose(cbs->private_data, "(%02x) nospec\n", insn->code);
0217         } else {
0218             verbose(cbs->private_data, "BUG_st_%02x\n", insn->code);
0219         }
0220     } else if (class == BPF_LDX) {
0221         if (BPF_MODE(insn->code) != BPF_MEM) {
0222             verbose(cbs->private_data, "BUG_ldx_%02x\n", insn->code);
0223             return;
0224         }
0225         verbose(cbs->private_data, "(%02x) r%d = *(%s *)(r%d %+d)\n",
0226             insn->code, insn->dst_reg,
0227             bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
0228             insn->src_reg, insn->off);
0229     } else if (class == BPF_LD) {
0230         if (BPF_MODE(insn->code) == BPF_ABS) {
0231             verbose(cbs->private_data, "(%02x) r0 = *(%s *)skb[%d]\n",
0232                 insn->code,
0233                 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
0234                 insn->imm);
0235         } else if (BPF_MODE(insn->code) == BPF_IND) {
0236             verbose(cbs->private_data, "(%02x) r0 = *(%s *)skb[r%d + %d]\n",
0237                 insn->code,
0238                 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
0239                 insn->src_reg, insn->imm);
0240         } else if (BPF_MODE(insn->code) == BPF_IMM &&
0241                BPF_SIZE(insn->code) == BPF_DW) {
0242             /* At this point, we already made sure that the second
0243              * part of the ldimm64 insn is accessible.
0244              */
0245             u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm;
0246             bool is_ptr = insn->src_reg == BPF_PSEUDO_MAP_FD ||
0247                       insn->src_reg == BPF_PSEUDO_MAP_VALUE;
0248             char tmp[64];
0249 
0250             if (is_ptr && !allow_ptr_leaks)
0251                 imm = 0;
0252 
0253             verbose(cbs->private_data, "(%02x) r%d = %s\n",
0254                 insn->code, insn->dst_reg,
0255                 __func_imm_name(cbs, insn, imm,
0256                         tmp, sizeof(tmp)));
0257         } else {
0258             verbose(cbs->private_data, "BUG_ld_%02x\n", insn->code);
0259             return;
0260         }
0261     } else if (class == BPF_JMP32 || class == BPF_JMP) {
0262         u8 opcode = BPF_OP(insn->code);
0263 
0264         if (opcode == BPF_CALL) {
0265             char tmp[64];
0266 
0267             if (insn->src_reg == BPF_PSEUDO_CALL) {
0268                 verbose(cbs->private_data, "(%02x) call pc%s\n",
0269                     insn->code,
0270                     __func_get_name(cbs, insn,
0271                             tmp, sizeof(tmp)));
0272             } else {
0273                 strcpy(tmp, "unknown");
0274                 verbose(cbs->private_data, "(%02x) call %s#%d\n", insn->code,
0275                     __func_get_name(cbs, insn,
0276                             tmp, sizeof(tmp)),
0277                     insn->imm);
0278             }
0279         } else if (insn->code == (BPF_JMP | BPF_JA)) {
0280             verbose(cbs->private_data, "(%02x) goto pc%+d\n",
0281                 insn->code, insn->off);
0282         } else if (insn->code == (BPF_JMP | BPF_EXIT)) {
0283             verbose(cbs->private_data, "(%02x) exit\n", insn->code);
0284         } else if (BPF_SRC(insn->code) == BPF_X) {
0285             verbose(cbs->private_data,
0286                 "(%02x) if %c%d %s %c%d goto pc%+d\n",
0287                 insn->code, class == BPF_JMP32 ? 'w' : 'r',
0288                 insn->dst_reg,
0289                 bpf_jmp_string[BPF_OP(insn->code) >> 4],
0290                 class == BPF_JMP32 ? 'w' : 'r',
0291                 insn->src_reg, insn->off);
0292         } else {
0293             verbose(cbs->private_data,
0294                 "(%02x) if %c%d %s 0x%x goto pc%+d\n",
0295                 insn->code, class == BPF_JMP32 ? 'w' : 'r',
0296                 insn->dst_reg,
0297                 bpf_jmp_string[BPF_OP(insn->code) >> 4],
0298                 insn->imm, insn->off);
0299         }
0300     } else {
0301         verbose(cbs->private_data, "(%02x) %s\n",
0302             insn->code, bpf_class_string[class]);
0303     }
0304 }
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