/* * Load, verify and execute ClamAV bytecode. * * Copyright (C) 2009 Sourcefire, Inc. * * Authors: Török Edvin * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, * MA 02110-1301, USA. */ #if HAVE_CONFIG_H #include "clamav-config.h" #endif #include "clamav.h" #include "others.h" #include "bytecode.h" #include "readdb.h" #include <string.h> typedef uint32_t operand_t; typedef uint16_t bbid_t; typedef uint16_t funcid_t; struct cli_bc_callop { operand_t* ops; uint8_t numOps; funcid_t funcid; }; struct branch { operand_t condition; bbid_t br_true; bbid_t br_false; }; #define MAX_OP (operand_t)(~0u) #define CONSTANT_OP (MAX_OP-1) #define ARG_OP (MAX_OP-1) struct cli_bc_value { uint64_t v; operand_t ref;/* this has CONSTANT_OP value for constants, and ARG_op for arguments */ }; struct cli_bc_inst { enum bc_opcode opcode; uint16_t type; union { operand_t unaryop; operand_t binop[2]; operand_t three[3]; struct cli_bc_callop ops; struct branch branch; bbid_t jump; } u; }; struct cli_bc_bb { unsigned numInsts; struct cli_bc_inst *insts; }; struct cli_bc_func { uint8_t numArgs; uint16_t numLocals; uint32_t numInsts; uint32_t numConstants; uint16_t numBB; uint16_t *types; uint32_t insn_idx; struct cli_bc_bb *BB; struct cli_bc_inst *allinsts; struct cli_bc_value *values; }; struct cli_bc_ctx { unsigned dummy; }; struct cli_bc_ctx *cli_bytecode_alloc_context(void) { struct cli_bc_ctx *ctx = cli_malloc(sizeof(*ctx)); return ctx; } void cli_bytecode_destroy_context(struct cli_bc_ctx *ctx) { free(ctx); } static inline uint64_t readNumber(const unsigned char *p, unsigned *off, unsigned len, char *ok) { uint64_t n=0; unsigned i, newoff, lim, p0 = p[*off], shift=0; lim = p0 - 0x60; if (lim > 0x10) { cli_errmsg("Invalid number type: %c\n", p0); *ok = 0; return 0; } newoff = *off +lim+1; if (newoff > len) { cli_errmsg("End of line encountered while reading number\n"); *ok = 0; return 0; } if (p0 == 0x60) { *off = newoff; return 0; } for (i=*off+1;i < newoff; i++) { uint64_t v = p[i]; if (UNLIKELY((v&0xf0) != 0x60)) { cli_errmsg("Invalid number part: %c\n", (char)v); *ok = 0; return 0; } v &= 0xf; v <<= shift; n |= v; shift += 4; } *off = newoff; return n; } static inline funcid_t readFuncID(struct cli_bc *bc, unsigned char *p, unsigned *off, unsigned len, char *ok) { funcid_t id = readNumber(p, off, len, ok); if (id >= bc->num_func) { cli_errmsg("Called function out of range: %u >= %u\n", id, bc->num_func); *ok = 0; return ~0; } return id; } static inline operand_t readOperand(struct cli_bc_func *func, unsigned char *p, unsigned *off, unsigned len, char *ok) { uint64_t v; unsigned numValues = func->numArgs + func->numInsts + func->numConstants; if ((p[*off]&0xf0) == 0x40) { p[*off] |= 0x20; /* TODO: unique constants */ func->values = cli_realloc2(func->values, (numValues+1)*sizeof(*func->values)); if (!func->values) { *ok = 0; return MAX_OP; } func->numConstants++; func->values[numValues].v = readNumber(p, off, len, ok); func->values[numValues].ref = CONSTANT_OP; return numValues; } v = readNumber(p, off, len, ok); if (!*ok) return MAX_OP; if (v >= numValues) { cli_errmsg("Operand index exceeds bounds: %u >= %u!\n", v, numValues); *ok = 0; return MAX_OP; } return v; } static inline unsigned readFixedNumber(const unsigned char *p, unsigned *off, unsigned len, char *ok, unsigned width) { unsigned i, n=0, shift=0; unsigned newoff = *off + width; if (newoff > len) { cli_errmsg("Newline encountered while reading number\n"); *ok = 0; return 0; } for (i=*off;i<newoff;i++) { unsigned v = p[i]; if (UNLIKELY((v&0xf0) != 0x60)) { cli_errmsg("Invalid number part: %c\n", v); *ok = 0; return 0; } v &= 0xf; v <<= shift; n |= v; shift += 4; } *off = newoff; return n; } static inline unsigned char *readData(const unsigned char *p, unsigned *off, unsigned len, char *ok, unsigned *datalen) { unsigned char *dat, *q; unsigned l, newoff, i; if (p[*off] != '|') { cli_errmsg("Data start marker missing: %c\n", p[*off]); *ok = 0; return NULL; } (*off)++; l = readNumber(p, off, len, ok); if (!l) return NULL; newoff = *off + l; if (newoff > len) { cli_errmsg("Line ended while reading data\n"); *ok = 0; return 0; } dat = cli_malloc(l); if (!dat) { cli_errmsg("Cannot allocate memory for data\n"); *ok = 0; return NULL; } q = dat; for (i=*off;i<newoff;i++) { const unsigned char v = p[i]; if (UNLIKELY((v&0xf0) != 0x60)) { cli_errmsg("Invalid data part: %c\n", v); *ok = 0; return 0; } *q++ = v; } *off = newoff; *datalen = l; return dat; } static inline char *readString(const unsigned char *p, unsigned *off, unsigned len, char *ok) { unsigned stringlen; char *str = (char*)readData(p, off, len, ok, &stringlen); if (*ok && stringlen && str[stringlen-1] != '\0') { free(str); *ok = 0; return NULL; } return str; } static int parseHeader(struct cli_bc *bc, unsigned char *buffer) { uint64_t magic1; unsigned magic2; char ok = 1; unsigned offset, len, flevel; if (strncmp(buffer, BC_HEADER, sizeof(BC_HEADER)-1)) { cli_errmsg("Missing file magic in bytecode"); return CL_EMALFDB; } offset = sizeof(BC_HEADER)-1; len = strlen((const char*)buffer); flevel = readNumber(buffer, &offset, len, &ok); if (!ok) { cli_errmsg("Unable to parse functionality level in bytecode header\n"); return CL_EMALFDB; } if (flevel > BC_FUNC_LEVEL) { cli_dbgmsg("Skipping bytecode with functionality level: %u\n", flevel); return CL_BREAK; } // Optimistic parsing, check for error only at the end. bc->verifier = readNumber(buffer, &offset, len, &ok); bc->sigmaker = readString(buffer, &offset, len, &ok); bc->id = readNumber(buffer, &offset, len, &ok); bc->metadata.maxStack = readNumber(buffer, &offset, len, &ok); bc->metadata.maxMem = readNumber(buffer, &offset, len, &ok); bc->metadata.maxTime = readNumber(buffer, &offset, len, &ok); bc->metadata.targetExclude = readString(buffer, &offset, len, &ok); bc->num_func = readNumber(buffer, &offset, len, &ok); if (!ok) { cli_errmsg("Invalid bytecode header at %u\n", offset); return CL_EMALFDB; } magic1 = readNumber(buffer, &offset, len, &ok); magic2 = readFixedNumber(buffer, &offset, len, &ok, 2); if (!ok || magic1 != 0x53e5493e9f3d1c30ull || magic2 != 42) { unsigned long m0 = magic1 >> 32; unsigned long m1 = magic1; cli_errmsg("Magic numbers don't match: %lx%lx, %u\n", m0, m1, magic2); return CL_EMALFDB; } if (offset != len) { cli_errmsg("Trailing garbage in bytecode header: %d extra bytes\n", len-offset); return CL_EMALFDB; } bc->funcs = cli_calloc(bc->num_func, sizeof(*bc->funcs)); if (!bc->funcs) { cli_errmsg("Out of memory allocating %u functions\n", bc->num_func); return CL_EMEM; } return CL_SUCCESS; } static int parseFunctionHeader(struct cli_bc *bc, unsigned fn, unsigned char *buffer) { char ok=1; unsigned offset, len, all_locals=0, i; struct cli_bc_func *func; if (fn >= bc->num_func) { cli_errmsg("Found more functions than declared: %u >= %u\n", fn, bc->num_func); return CL_EMALFDB; } func = &bc->funcs[fn]; len = strlen((const char*)buffer); if (buffer[0] != 'A') { cli_errmsg("Invalid function arguments header: %c\n", buffer[0]); return CL_EMALFDB; } offset = 1; func->numArgs = readFixedNumber(buffer, &offset, len, &ok, 1); if (buffer[offset] != 'L') { cli_errmsg("Invalid function locals header: %c\n", buffer[offset]); return CL_EMALFDB; } offset++; func->numLocals = readNumber(buffer, &offset, len, &ok); if (!ok) { cli_errmsg("Invalid number of arguments/locals\n"); return CL_EMALFDB; } all_locals = func->numArgs + func->numLocals; func->types = cli_calloc(all_locals, sizeof(*func->types)); if (!func->types) { cli_errmsg("Out of memory allocating function arguments\n"); return CL_EMEM; } for (i=0;i<all_locals;i++) { func->types[i] = readNumber(buffer, &offset, len, &ok); } if (!ok) { cli_errmsg("Invalid local types\n"); return CL_EMALFDB; } if (buffer[offset] != 'F') { cli_errmsg("Invalid function body header: %c\n", buffer[offset]); return CL_EMALFDB; } offset++; func->numInsts = readNumber(buffer, &offset, len, &ok); if (!ok ){ cli_errmsg("Invalid instructions count\n"); return CL_EMALFDB; } func->insn_idx = 0; func->numConstants=0; func->allinsts = cli_calloc(func->numInsts, sizeof(*func->allinsts)); if (!func->allinsts) { cli_errmsg("Out of memory allocating instructions\n"); return CL_EMEM; } func->values = cli_calloc(func->numInsts+func->numArgs, sizeof(*func->values)); if (!func->values) { cli_errmsg("Out of memory allocating values\n"); return CL_EMEM; } for (i=0;i<func->numArgs;i++) { func->values[i].v = 0xdeadbeef; func->values[i].ref = ARG_OP; } for(;i<func->numInsts+func->numArgs;i++) { func->values[i].v = 0xdeadbeef; func->values[i].ref = i-func->numArgs; } func->numBB = readNumber(buffer, &offset, len, &ok); if (!ok) { cli_errmsg("Invalid basic block count\n"); return CL_EMALFDB; } func->BB = cli_calloc(func->numBB, sizeof(*func->BB)); if (!func->BB) { cli_errmsg("Out of memory allocating basic blocks\n"); return CL_EMEM; } return CL_SUCCESS; } static bbid_t readBBID(struct cli_bc_func *func, const unsigned char *buffer, unsigned *off, unsigned len, char *ok) { unsigned id = readNumber(buffer, off, len, ok); if (!id || id >= func->numBB) { cli_errmsg("Basic block ID out of range: %u\n", id); *ok = 0; } if (!*ok) return ~0; return id; } static int parseBB(struct cli_bc *bc, unsigned func, unsigned bb, unsigned char *buffer) { char ok=1; unsigned offset, len, last = 0; struct cli_bc_bb *BB; struct cli_bc_func *bcfunc = &bc->funcs[func]; struct cli_bc_inst inst; if (bb >= bcfunc->numBB) { cli_errmsg("Found too many basic blocks\n"); return CL_EMALFDB; } BB = &bcfunc->BB[bb]; len = strlen((const char*) buffer); if (buffer[0] != 'B') { cli_errmsg("Invalid basic block header: %c\n", buffer[0]); return CL_EMALFDB; } offset = 1; BB->numInsts = 0; BB->insts = &bcfunc->allinsts[bcfunc->insn_idx]; while (!last) { unsigned numOp, i; if (buffer[offset] == 'T') { last = 1; offset++; /* terminators are void */ inst.type = 0; } else { inst.type = readNumber(buffer, &offset, len, &ok); } inst.opcode = readFixedNumber(buffer, &offset, len, &ok, 2); if (!ok) { cli_errmsg("Invalid type or operand\n"); return CL_EMALFDB; } if (inst.opcode >= OP_INVALID) { cli_errmsg("Invalid opcode: %u\n", inst.opcode); return CL_EMALFDB; } switch (inst.opcode) { case OP_JMP: inst.u.jump = readBBID(bcfunc, buffer, &offset, len, &ok); break; case OP_BRANCH: inst.u.branch.condition = readOperand(bcfunc, buffer, &offset, len, &ok); inst.u.branch.br_true = readBBID(bcfunc, buffer, &offset, len, &ok); inst.u.branch.br_false = readBBID(bcfunc, buffer, &offset, len, &ok); break; case OP_CALL_DIRECT: numOp = readFixedNumber(buffer, &offset, len, &ok, 1); if (ok) { inst.u.ops.numOps = numOp; inst.u.ops.ops = cli_calloc(numOp, sizeof(*inst.u.ops.ops)); if (!inst.u.ops.ops) { cli_errmsg("Out of memory allocating operands\n"); return CL_EMALFDB; } inst.u.ops.funcid = readFuncID(bc, buffer, &offset, len, &ok); for (i=0;i<numOp;i++) { inst.u.ops.ops[i] = readOperand(bcfunc, buffer, &offset, len, &ok); } } break; default: numOp = operand_counts[inst.opcode]; switch (numOp) { case 1: inst.u.unaryop = readOperand(bcfunc, buffer, &offset, len, &ok); break; case 2: inst.u.binop[0] = readOperand(bcfunc, buffer, &offset, len, &ok); inst.u.binop[1] = readOperand(bcfunc, buffer, &offset, len, &ok); break; case 3: inst.u.three[0] = readOperand(bcfunc, buffer, &offset, len, &ok); inst.u.three[1] = readOperand(bcfunc, buffer, &offset, len, &ok); inst.u.three[2] = readOperand(bcfunc, buffer, &offset, len, &ok); break; default: cli_errmsg("Opcode with too many operands: %u?\n", numOp); ok = 0; break; } } if (!ok) { cli_errmsg("Invalid instructions or operands\n"); return CL_EMALFDB; } if (bcfunc->insn_idx + BB->numInsts >= bcfunc->numInsts) { cli_errmsg("More instructions than declared in total!\n"); return CL_EMALFDB; } BB->insts[BB->numInsts++] = inst; } if (bb == bc->funcs[func].numBB-1) { if (buffer[offset] != 'E') { cli_errmsg("Missing basicblock terminator, got: %c\n", buffer[offset]); return CL_EMALFDB; } offset++; } cli_dbgmsg("Parsed %d instructions\n", BB->numInsts); if (offset != len) { cli_errmsg("Trailing garbage in basicblock: %d extra bytes\n", len-offset); return CL_EMALFDB; } return CL_SUCCESS; } enum parse_state { PARSE_BC_HEADER=0, PARSE_FUNC_HEADER, PARSE_BB }; int cli_bytecode_load(struct cli_bc *bc, FILE *f, struct cli_dbio *dbio) { unsigned row = 0, current_func = 0, bb=0; char buffer[FILEBUFF]; enum parse_state state = PARSE_BC_HEADER; if (!f && !dbio) { cli_errmsg("Unable to load bytecode (null file)\n"); return CL_ENULLARG; } while (cli_dbgets(buffer, FILEBUFF, f, dbio)) { int rc; cli_chomp(buffer); row++; switch (state) { case PARSE_BC_HEADER: rc = parseHeader(bc, (unsigned char*)buffer); if (rc == CL_BREAK) /* skip */ return CL_SUCCESS; if (rc != CL_SUCCESS) { cli_errmsg("Error at bytecode line %u\n", row); return rc; } state = PARSE_FUNC_HEADER; break; case PARSE_FUNC_HEADER: rc = parseFunctionHeader(bc, current_func, (unsigned char*)buffer); if (rc != CL_SUCCESS) { cli_errmsg("Error at bytecode line %u\n", row); return rc; } bb = 0; state = PARSE_BB; break; case PARSE_BB: rc = parseBB(bc, current_func, bb++, (unsigned char*)buffer); if (rc != CL_SUCCESS) { cli_errmsg("Error at bytecode line %u\n", row); return rc; } if (bb >= bc->funcs[current_func].numBB) { state = PARSE_FUNC_HEADER; current_func++; } break; } } cli_dbgmsg("Parsed %d functions\n", current_func); return CL_SUCCESS; } void cli_bytecode_run(struct cli_bc *bc, struct cli_bc_ctx *ctx) { } void cli_bytecode_destroy(struct cli_bc *bc) { unsigned i, j, k; free(bc->sigmaker); free(bc->metadata.targetExclude); for (i=0;i<bc->num_func;i++) { struct cli_bc_func *f = &bc->funcs[i]; free(f->types); for (j=0;j<f->numBB;j++) { struct cli_bc_bb *BB = &f->BB[j]; for(k=0;k<BB->numInsts;k++) { struct cli_bc_inst *i = &BB->insts[k]; if (operand_counts[i->opcode] > 3) free(i->u.ops.ops); } } free(f->BB); free(f->allinsts); free(f->values); } free(bc->funcs); }