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bpf_validate.c
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bpf_validate.c
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/* SPDX-License-Identifier: BSD-3-Clause
* Copyright(c) 2018 Intel Corporation
*/
#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <stdint.h>
#include <inttypes.h>
#include <rte_common.h>
#include <rte_eal.h>
#include <rte_byteorder.h>
#include "bpf_impl.h"
#define BPF_ARG_PTR_STACK RTE_BPF_ARG_RESERVED
struct bpf_reg_val {
struct rte_bpf_arg v;
uint64_t mask;
struct {
int64_t min;
int64_t max;
} s;
struct {
uint64_t min;
uint64_t max;
} u;
};
struct bpf_eval_state {
struct bpf_reg_val rv[EBPF_REG_NUM];
struct bpf_reg_val sv[MAX_BPF_STACK_SIZE / sizeof(uint64_t)];
};
/* possible instruction node colour */
enum {
WHITE,
GREY,
BLACK,
MAX_NODE_COLOUR
};
/* possible edge types */
enum {
UNKNOWN_EDGE,
TREE_EDGE,
BACK_EDGE,
CROSS_EDGE,
MAX_EDGE_TYPE
};
#define MAX_EDGES 2
struct inst_node {
uint8_t colour;
uint8_t nb_edge:4;
uint8_t cur_edge:4;
uint8_t edge_type[MAX_EDGES];
uint32_t edge_dest[MAX_EDGES];
uint32_t prev_node;
struct bpf_eval_state *evst;
};
struct bpf_verifier {
const struct rte_bpf_prm *prm;
struct inst_node *in;
uint64_t stack_sz;
uint32_t nb_nodes;
uint32_t nb_jcc_nodes;
uint32_t nb_ldmb_nodes;
uint32_t node_colour[MAX_NODE_COLOUR];
uint32_t edge_type[MAX_EDGE_TYPE];
struct bpf_eval_state *evst;
struct inst_node *evin;
struct {
uint32_t num;
uint32_t cur;
struct bpf_eval_state *ent;
} evst_pool;
};
struct bpf_ins_check {
struct {
uint16_t dreg;
uint16_t sreg;
} mask;
struct {
uint16_t min;
uint16_t max;
} off;
struct {
uint32_t min;
uint32_t max;
} imm;
const char * (*check)(const struct ebpf_insn *);
const char * (*eval)(struct bpf_verifier *, const struct ebpf_insn *);
};
#define ALL_REGS RTE_LEN2MASK(EBPF_REG_NUM, uint16_t)
#define WRT_REGS RTE_LEN2MASK(EBPF_REG_10, uint16_t)
#define ZERO_REG RTE_LEN2MASK(EBPF_REG_1, uint16_t)
/* For LD_IND R6 is an implicit CTX register. */
#define IND_SRC_REGS (WRT_REGS ^ 1 << EBPF_REG_6)
/*
* check and evaluate functions for particular instruction types.
*/
static const char *
check_alu_bele(const struct ebpf_insn *ins)
{
if (ins->imm != 16 && ins->imm != 32 && ins->imm != 64)
return "invalid imm field";
return NULL;
}
static const char *
eval_exit(struct bpf_verifier *bvf, const struct ebpf_insn *ins)
{
RTE_SET_USED(ins);
if (bvf->evst->rv[EBPF_REG_0].v.type == RTE_BPF_ARG_UNDEF)
return "undefined return value";
return NULL;
}
/* setup max possible with this mask bounds */
static void
eval_umax_bound(struct bpf_reg_val *rv, uint64_t mask)
{
rv->u.max = mask;
rv->u.min = 0;
}
static void
eval_smax_bound(struct bpf_reg_val *rv, uint64_t mask)
{
rv->s.max = mask >> 1;
rv->s.min = rv->s.max ^ UINT64_MAX;
}
static void
eval_max_bound(struct bpf_reg_val *rv, uint64_t mask)
{
eval_umax_bound(rv, mask);
eval_smax_bound(rv, mask);
}
static void
eval_fill_max_bound(struct bpf_reg_val *rv, uint64_t mask)
{
eval_max_bound(rv, mask);
rv->v.type = RTE_BPF_ARG_RAW;
rv->mask = mask;
}
static void
eval_fill_imm64(struct bpf_reg_val *rv, uint64_t mask, uint64_t val)
{
rv->mask = mask;
rv->s.min = val;
rv->s.max = val;
rv->u.min = val;
rv->u.max = val;
}
static void
eval_fill_imm(struct bpf_reg_val *rv, uint64_t mask, int32_t imm)
{
uint64_t v;
v = (uint64_t)imm & mask;
rv->v.type = RTE_BPF_ARG_RAW;
eval_fill_imm64(rv, mask, v);
}
static const char *
eval_ld_imm64(struct bpf_verifier *bvf, const struct ebpf_insn *ins)
{
uint32_t i;
uint64_t val;
struct bpf_reg_val *rd;
val = (uint32_t)ins[0].imm | (uint64_t)(uint32_t)ins[1].imm << 32;
rd = bvf->evst->rv + ins->dst_reg;
rd->v.type = RTE_BPF_ARG_RAW;
eval_fill_imm64(rd, UINT64_MAX, val);
for (i = 0; i != bvf->prm->nb_xsym; i++) {
/* load of external variable */
if (bvf->prm->xsym[i].type == RTE_BPF_XTYPE_VAR &&
(uintptr_t)bvf->prm->xsym[i].var.val == val) {
rd->v = bvf->prm->xsym[i].var.desc;
eval_fill_imm64(rd, UINT64_MAX, 0);
break;
}
}
return NULL;
}
static void
eval_apply_mask(struct bpf_reg_val *rv, uint64_t mask)
{
struct bpf_reg_val rt;
rt.u.min = rv->u.min & mask;
rt.u.max = rv->u.max & mask;
if (rt.u.min != rv->u.min || rt.u.max != rv->u.max) {
rv->u.max = RTE_MAX(rt.u.max, mask);
rv->u.min = 0;
}
eval_smax_bound(&rt, mask);
rv->s.max = RTE_MIN(rt.s.max, rv->s.max);
rv->s.min = RTE_MAX(rt.s.min, rv->s.min);
rv->mask = mask;
}
static void
eval_add(struct bpf_reg_val *rd, const struct bpf_reg_val *rs, uint64_t msk)
{
struct bpf_reg_val rv;
rv.u.min = (rd->u.min + rs->u.min) & msk;
rv.u.max = (rd->u.max + rs->u.max) & msk;
rv.s.min = (rd->s.min + rs->s.min) & msk;
rv.s.max = (rd->s.max + rs->s.max) & msk;
/*
* if at least one of the operands is not constant,
* then check for overflow
*/
if ((rd->u.min != rd->u.max || rs->u.min != rs->u.max) &&
(rv.u.min < rd->u.min || rv.u.max < rd->u.max))
eval_umax_bound(&rv, msk);
if ((rd->s.min != rd->s.max || rs->s.min != rs->s.max) &&
(((rs->s.min < 0 && rv.s.min > rd->s.min) ||
rv.s.min < rd->s.min) ||
((rs->s.max < 0 && rv.s.max > rd->s.max) ||
rv.s.max < rd->s.max)))
eval_smax_bound(&rv, msk);
rd->s = rv.s;
rd->u = rv.u;
}
static void
eval_sub(struct bpf_reg_val *rd, const struct bpf_reg_val *rs, uint64_t msk)
{
struct bpf_reg_val rv;
rv.u.min = (rd->u.min - rs->u.max) & msk;
rv.u.max = (rd->u.max - rs->u.min) & msk;
rv.s.min = (rd->s.min - rs->s.max) & msk;
rv.s.max = (rd->s.max - rs->s.min) & msk;
/*
* if at least one of the operands is not constant,
* then check for overflow
*/
if ((rd->u.min != rd->u.max || rs->u.min != rs->u.max) &&
(rv.u.min > rd->u.min || rv.u.max > rd->u.max))
eval_umax_bound(&rv, msk);
if ((rd->s.min != rd->s.max || rs->s.min != rs->s.max) &&
(((rs->s.min < 0 && rv.s.min < rd->s.min) ||
rv.s.min > rd->s.min) ||
((rs->s.max < 0 && rv.s.max < rd->s.max) ||
rv.s.max > rd->s.max)))
eval_smax_bound(&rv, msk);
rd->s = rv.s;
rd->u = rv.u;
}
static void
eval_lsh(struct bpf_reg_val *rd, const struct bpf_reg_val *rs, size_t opsz,
uint64_t msk)
{
/* check if shift value is less then max result bits */
if (rs->u.max >= opsz) {
eval_max_bound(rd, msk);
return;
}
/* check for overflow */
if (rd->u.max > RTE_LEN2MASK(opsz - rs->u.max, uint64_t))
eval_umax_bound(rd, msk);
else {
rd->u.max <<= rs->u.max;
rd->u.min <<= rs->u.min;
}
/* check that dreg values are and would remain always positive */
if ((uint64_t)rd->s.min >> (opsz - 1) != 0 || rd->s.max >=
RTE_LEN2MASK(opsz - rs->u.max - 1, int64_t))
eval_smax_bound(rd, msk);
else {
rd->s.max <<= rs->u.max;
rd->s.min <<= rs->u.min;
}
}
static void
eval_rsh(struct bpf_reg_val *rd, const struct bpf_reg_val *rs, size_t opsz,
uint64_t msk)
{
/* check if shift value is less then max result bits */
if (rs->u.max >= opsz) {
eval_max_bound(rd, msk);
return;
}
rd->u.max >>= rs->u.min;
rd->u.min >>= rs->u.max;
/* check that dreg values are always positive */
if ((uint64_t)rd->s.min >> (opsz - 1) != 0)
eval_smax_bound(rd, msk);
else {
rd->s.max >>= rs->u.min;
rd->s.min >>= rs->u.max;
}
}
static void
eval_arsh(struct bpf_reg_val *rd, const struct bpf_reg_val *rs, size_t opsz,
uint64_t msk)
{
uint32_t shv;
/* check if shift value is less then max result bits */
if (rs->u.max >= opsz) {
eval_max_bound(rd, msk);
return;
}
rd->u.max = (int64_t)rd->u.max >> rs->u.min;
rd->u.min = (int64_t)rd->u.min >> rs->u.max;
/* if we have 32-bit values - extend them to 64-bit */
if (opsz == sizeof(uint32_t) * CHAR_BIT) {
rd->s.min <<= opsz;
rd->s.max <<= opsz;
shv = opsz;
} else
shv = 0;
if (rd->s.min < 0)
rd->s.min = (rd->s.min >> (rs->u.min + shv)) & msk;
else
rd->s.min = (rd->s.min >> (rs->u.max + shv)) & msk;
if (rd->s.max < 0)
rd->s.max = (rd->s.max >> (rs->u.max + shv)) & msk;
else
rd->s.max = (rd->s.max >> (rs->u.min + shv)) & msk;
}
static uint64_t
eval_umax_bits(uint64_t v, size_t opsz)
{
if (v == 0)
return 0;
v = __builtin_clzll(v);
return RTE_LEN2MASK(opsz - v, uint64_t);
}
/* estimate max possible value for (v1 & v2) */
static uint64_t
eval_uand_max(uint64_t v1, uint64_t v2, size_t opsz)
{
v1 = eval_umax_bits(v1, opsz);
v2 = eval_umax_bits(v2, opsz);
return (v1 & v2);
}
/* estimate max possible value for (v1 | v2) */
static uint64_t
eval_uor_max(uint64_t v1, uint64_t v2, size_t opsz)
{
v1 = eval_umax_bits(v1, opsz);
v2 = eval_umax_bits(v2, opsz);
return (v1 | v2);
}
static void
eval_and(struct bpf_reg_val *rd, const struct bpf_reg_val *rs, size_t opsz,
uint64_t msk)
{
/* both operands are constants */
if (rd->u.min == rd->u.max && rs->u.min == rs->u.max) {
rd->u.min &= rs->u.min;
rd->u.max &= rs->u.max;
} else {
rd->u.max = eval_uand_max(rd->u.max, rs->u.max, opsz);
rd->u.min &= rs->u.min;
}
/* both operands are constants */
if (rd->s.min == rd->s.max && rs->s.min == rs->s.max) {
rd->s.min &= rs->s.min;
rd->s.max &= rs->s.max;
/* at least one of operand is non-negative */
} else if (rd->s.min >= 0 || rs->s.min >= 0) {
rd->s.max = eval_uand_max(rd->s.max & (msk >> 1),
rs->s.max & (msk >> 1), opsz);
rd->s.min &= rs->s.min;
} else
eval_smax_bound(rd, msk);
}
static void
eval_or(struct bpf_reg_val *rd, const struct bpf_reg_val *rs, size_t opsz,
uint64_t msk)
{
/* both operands are constants */
if (rd->u.min == rd->u.max && rs->u.min == rs->u.max) {
rd->u.min |= rs->u.min;
rd->u.max |= rs->u.max;
} else {
rd->u.max = eval_uor_max(rd->u.max, rs->u.max, opsz);
rd->u.min |= rs->u.min;
}
/* both operands are constants */
if (rd->s.min == rd->s.max && rs->s.min == rs->s.max) {
rd->s.min |= rs->s.min;
rd->s.max |= rs->s.max;
/* both operands are non-negative */
} else if (rd->s.min >= 0 || rs->s.min >= 0) {
rd->s.max = eval_uor_max(rd->s.max, rs->s.max, opsz);
rd->s.min |= rs->s.min;
} else
eval_smax_bound(rd, msk);
}
static void
eval_xor(struct bpf_reg_val *rd, const struct bpf_reg_val *rs, size_t opsz,
uint64_t msk)
{
/* both operands are constants */
if (rd->u.min == rd->u.max && rs->u.min == rs->u.max) {
rd->u.min ^= rs->u.min;
rd->u.max ^= rs->u.max;
} else {
rd->u.max = eval_uor_max(rd->u.max, rs->u.max, opsz);
rd->u.min = 0;
}
/* both operands are constants */
if (rd->s.min == rd->s.max && rs->s.min == rs->s.max) {
rd->s.min ^= rs->s.min;
rd->s.max ^= rs->s.max;
/* both operands are non-negative */
} else if (rd->s.min >= 0 || rs->s.min >= 0) {
rd->s.max = eval_uor_max(rd->s.max, rs->s.max, opsz);
rd->s.min = 0;
} else
eval_smax_bound(rd, msk);
}
static void
eval_mul(struct bpf_reg_val *rd, const struct bpf_reg_val *rs, size_t opsz,
uint64_t msk)
{
/* both operands are constants */
if (rd->u.min == rd->u.max && rs->u.min == rs->u.max) {
rd->u.min = (rd->u.min * rs->u.min) & msk;
rd->u.max = (rd->u.max * rs->u.max) & msk;
/* check for overflow */
} else if (rd->u.max <= msk >> opsz / 2 && rs->u.max <= msk >> opsz) {
rd->u.max *= rs->u.max;
rd->u.min *= rd->u.min;
} else
eval_umax_bound(rd, msk);
/* both operands are constants */
if (rd->s.min == rd->s.max && rs->s.min == rs->s.max) {
rd->s.min = (rd->s.min * rs->s.min) & msk;
rd->s.max = (rd->s.max * rs->s.max) & msk;
/* check that both operands are positive and no overflow */
} else if (rd->s.min >= 0 && rs->s.min >= 0) {
rd->s.max *= rs->s.max;
rd->s.min *= rd->s.min;
} else
eval_smax_bound(rd, msk);
}
static const char *
eval_divmod(uint32_t op, struct bpf_reg_val *rd, struct bpf_reg_val *rs,
size_t opsz, uint64_t msk)
{
/* both operands are constants */
if (rd->u.min == rd->u.max && rs->u.min == rs->u.max) {
if (rs->u.max == 0)
return "division by 0";
if (op == BPF_DIV) {
rd->u.min /= rs->u.min;
rd->u.max /= rs->u.max;
} else {
rd->u.min %= rs->u.min;
rd->u.max %= rs->u.max;
}
} else {
if (op == BPF_MOD)
rd->u.max = RTE_MIN(rd->u.max, rs->u.max - 1);
else
rd->u.max = rd->u.max;
rd->u.min = 0;
}
/* if we have 32-bit values - extend them to 64-bit */
if (opsz == sizeof(uint32_t) * CHAR_BIT) {
rd->s.min = (int32_t)rd->s.min;
rd->s.max = (int32_t)rd->s.max;
rs->s.min = (int32_t)rs->s.min;
rs->s.max = (int32_t)rs->s.max;
}
/* both operands are constants */
if (rd->s.min == rd->s.max && rs->s.min == rs->s.max) {
if (rs->s.max == 0)
return "division by 0";
if (op == BPF_DIV) {
rd->s.min /= rs->s.min;
rd->s.max /= rs->s.max;
} else {
rd->s.min %= rs->s.min;
rd->s.max %= rs->s.max;
}
} else if (op == BPF_MOD) {
rd->s.min = RTE_MAX(rd->s.max, 0);
rd->s.min = RTE_MIN(rd->s.min, 0);
} else
eval_smax_bound(rd, msk);
rd->s.max &= msk;
rd->s.min &= msk;
return NULL;
}
static void
eval_neg(struct bpf_reg_val *rd, size_t opsz, uint64_t msk)
{
uint64_t ux, uy;
int64_t sx, sy;
/* if we have 32-bit values - extend them to 64-bit */
if (opsz == sizeof(uint32_t) * CHAR_BIT) {
rd->u.min = (int32_t)rd->u.min;
rd->u.max = (int32_t)rd->u.max;
}
ux = -(int64_t)rd->u.min & msk;
uy = -(int64_t)rd->u.max & msk;
rd->u.max = RTE_MAX(ux, uy);
rd->u.min = RTE_MIN(ux, uy);
/* if we have 32-bit values - extend them to 64-bit */
if (opsz == sizeof(uint32_t) * CHAR_BIT) {
rd->s.min = (int32_t)rd->s.min;
rd->s.max = (int32_t)rd->s.max;
}
sx = -rd->s.min & msk;
sy = -rd->s.max & msk;
rd->s.max = RTE_MAX(sx, sy);
rd->s.min = RTE_MIN(sx, sy);
}
static const char *
eval_ld_mbuf(struct bpf_verifier *bvf, const struct ebpf_insn *ins)
{
uint32_t i, mode;
struct bpf_reg_val *rv, ri, rs;
mode = BPF_MODE(ins->code);
/* R6 is an implicit input that must contain pointer to mbuf */
if (bvf->evst->rv[EBPF_REG_6].v.type != RTE_BPF_ARG_PTR_MBUF)
return "invalid type for implicit ctx register";
if (mode == BPF_IND) {
rs = bvf->evst->rv[ins->src_reg];
if (rs.v.type != RTE_BPF_ARG_RAW)
return "unexpected type for src register";
eval_fill_imm(&ri, UINT64_MAX, ins->imm);
eval_add(&rs, &ri, UINT64_MAX);
if (rs.s.max < 0 || rs.u.min > UINT32_MAX)
return "mbuf boundary violation";
}
/* R1-R5 scratch registers */
for (i = EBPF_REG_1; i != EBPF_REG_6; i++)
bvf->evst->rv[i].v.type = RTE_BPF_ARG_UNDEF;
/* R0 is an implicit output, contains data fetched from the packet */
rv = bvf->evst->rv + EBPF_REG_0;
rv->v.size = bpf_size(BPF_SIZE(ins->code));
eval_fill_max_bound(rv, RTE_LEN2MASK(rv->v.size * CHAR_BIT, uint64_t));
return NULL;
}
/*
* check that destination and source operand are in defined state.
*/
static const char *
eval_defined(const struct bpf_reg_val *dst, const struct bpf_reg_val *src)
{
if (dst != NULL && dst->v.type == RTE_BPF_ARG_UNDEF)
return "dest reg value is undefined";
if (src != NULL && src->v.type == RTE_BPF_ARG_UNDEF)
return "src reg value is undefined";
return NULL;
}
static const char *
eval_alu(struct bpf_verifier *bvf, const struct ebpf_insn *ins)
{
uint64_t msk;
uint32_t op;
size_t opsz;
const char *err;
struct bpf_eval_state *st;
struct bpf_reg_val *rd, rs;
opsz = (BPF_CLASS(ins->code) == BPF_ALU) ?
sizeof(uint32_t) : sizeof(uint64_t);
opsz = opsz * CHAR_BIT;
msk = RTE_LEN2MASK(opsz, uint64_t);
st = bvf->evst;
rd = st->rv + ins->dst_reg;
if (BPF_SRC(ins->code) == BPF_X) {
rs = st->rv[ins->src_reg];
eval_apply_mask(&rs, msk);
} else
eval_fill_imm(&rs, msk, ins->imm);
eval_apply_mask(rd, msk);
op = BPF_OP(ins->code);
err = eval_defined((op != EBPF_MOV) ? rd : NULL,
(op != BPF_NEG) ? &rs : NULL);
if (err != NULL)
return err;
if (op == BPF_ADD)
eval_add(rd, &rs, msk);
else if (op == BPF_SUB)
eval_sub(rd, &rs, msk);
else if (op == BPF_LSH)
eval_lsh(rd, &rs, opsz, msk);
else if (op == BPF_RSH)
eval_rsh(rd, &rs, opsz, msk);
else if (op == EBPF_ARSH)
eval_arsh(rd, &rs, opsz, msk);
else if (op == BPF_AND)
eval_and(rd, &rs, opsz, msk);
else if (op == BPF_OR)
eval_or(rd, &rs, opsz, msk);
else if (op == BPF_XOR)
eval_xor(rd, &rs, opsz, msk);
else if (op == BPF_MUL)
eval_mul(rd, &rs, opsz, msk);
else if (op == BPF_DIV || op == BPF_MOD)
err = eval_divmod(op, rd, &rs, opsz, msk);
else if (op == BPF_NEG)
eval_neg(rd, opsz, msk);
else if (op == EBPF_MOV)
*rd = rs;
else
eval_max_bound(rd, msk);
return err;
}
static const char *
eval_bele(struct bpf_verifier *bvf, const struct ebpf_insn *ins)
{
uint64_t msk;
struct bpf_eval_state *st;
struct bpf_reg_val *rd;
const char *err;
msk = RTE_LEN2MASK(ins->imm, uint64_t);
st = bvf->evst;
rd = st->rv + ins->dst_reg;
err = eval_defined(rd, NULL);
if (err != NULL)
return err;
#if RTE_BYTE_ORDER == RTE_LITTLE_ENDIAN
if (ins->code == (BPF_ALU | EBPF_END | EBPF_TO_BE))
eval_max_bound(rd, msk);
else
eval_apply_mask(rd, msk);
#else
if (ins->code == (BPF_ALU | EBPF_END | EBPF_TO_LE))
eval_max_bound(rd, msk);
else
eval_apply_mask(rd, msk);
#endif
return NULL;
}
static const char *
eval_ptr(struct bpf_verifier *bvf, struct bpf_reg_val *rm, uint32_t opsz,
uint32_t align, int16_t off)
{
struct bpf_reg_val rv;
/* calculate reg + offset */
eval_fill_imm(&rv, rm->mask, off);
eval_add(rm, &rv, rm->mask);
if (RTE_BPF_ARG_PTR_TYPE(rm->v.type) == 0)
return "destination is not a pointer";
if (rm->mask != UINT64_MAX)
return "pointer truncation";
if (rm->u.max + opsz > rm->v.size ||
(uint64_t)rm->s.max + opsz > rm->v.size ||
rm->s.min < 0)
return "memory boundary violation";
if (rm->u.max % align != 0)
return "unaligned memory access";
if (rm->v.type == BPF_ARG_PTR_STACK) {
if (rm->u.max != rm->u.min || rm->s.max != rm->s.min ||
rm->u.max != (uint64_t)rm->s.max)
return "stack access with variable offset";
bvf->stack_sz = RTE_MAX(bvf->stack_sz, rm->v.size - rm->u.max);
/* pointer to mbuf */
} else if (rm->v.type == RTE_BPF_ARG_PTR_MBUF) {
if (rm->u.max != rm->u.min || rm->s.max != rm->s.min ||
rm->u.max != (uint64_t)rm->s.max)
return "mbuf access with variable offset";
}
return NULL;
}
static void
eval_max_load(struct bpf_reg_val *rv, uint64_t mask)
{
eval_umax_bound(rv, mask);
/* full 64-bit load */
if (mask == UINT64_MAX)
eval_smax_bound(rv, mask);
/* zero-extend load */
rv->s.min = rv->u.min;
rv->s.max = rv->u.max;
}
static const char *
eval_load(struct bpf_verifier *bvf, const struct ebpf_insn *ins)
{
uint32_t opsz;
uint64_t msk;
const char *err;
struct bpf_eval_state *st;
struct bpf_reg_val *rd, rs;
const struct bpf_reg_val *sv;
st = bvf->evst;
rd = st->rv + ins->dst_reg;
rs = st->rv[ins->src_reg];
opsz = bpf_size(BPF_SIZE(ins->code));
msk = RTE_LEN2MASK(opsz * CHAR_BIT, uint64_t);
err = eval_ptr(bvf, &rs, opsz, 1, ins->off);
if (err != NULL)
return err;
if (rs.v.type == BPF_ARG_PTR_STACK) {
sv = st->sv + rs.u.max / sizeof(uint64_t);
if (sv->v.type == RTE_BPF_ARG_UNDEF || sv->mask < msk)
return "undefined value on the stack";
*rd = *sv;
/* pointer to mbuf */
} else if (rs.v.type == RTE_BPF_ARG_PTR_MBUF) {
if (rs.u.max == offsetof(struct rte_mbuf, next)) {
eval_fill_imm(rd, msk, 0);
rd->v = rs.v;
} else if (rs.u.max == offsetof(struct rte_mbuf, buf_addr)) {
eval_fill_imm(rd, msk, 0);
rd->v.type = RTE_BPF_ARG_PTR;
rd->v.size = rs.v.buf_size;
} else if (rs.u.max == offsetof(struct rte_mbuf, data_off)) {
eval_fill_imm(rd, msk, RTE_PKTMBUF_HEADROOM);
rd->v.type = RTE_BPF_ARG_RAW;
} else {
eval_max_load(rd, msk);
rd->v.type = RTE_BPF_ARG_RAW;
}
/* pointer to raw data */
} else {
eval_max_load(rd, msk);
rd->v.type = RTE_BPF_ARG_RAW;
}
return NULL;
}
static const char *
eval_mbuf_store(const struct bpf_reg_val *rv, uint32_t opsz)
{
uint32_t i;
static const struct {
size_t off;
size_t sz;
} mbuf_ro_fileds[] = {
{ .off = offsetof(struct rte_mbuf, buf_addr), },
{ .off = offsetof(struct rte_mbuf, refcnt), },
{ .off = offsetof(struct rte_mbuf, nb_segs), },
{ .off = offsetof(struct rte_mbuf, buf_len), },
{ .off = offsetof(struct rte_mbuf, pool), },
{ .off = offsetof(struct rte_mbuf, next), },
{ .off = offsetof(struct rte_mbuf, priv_size), },
};
for (i = 0; i != RTE_DIM(mbuf_ro_fileds) &&
(mbuf_ro_fileds[i].off + mbuf_ro_fileds[i].sz <=
rv->u.max || rv->u.max + opsz <= mbuf_ro_fileds[i].off);
i++)
;
if (i != RTE_DIM(mbuf_ro_fileds))
return "store to the read-only mbuf field";
return NULL;
}
static const char *
eval_store(struct bpf_verifier *bvf, const struct ebpf_insn *ins)
{
uint32_t opsz;
uint64_t msk;
const char *err;
struct bpf_eval_state *st;
struct bpf_reg_val rd, rs, *sv;
opsz = bpf_size(BPF_SIZE(ins->code));
msk = RTE_LEN2MASK(opsz * CHAR_BIT, uint64_t);
st = bvf->evst;
rd = st->rv[ins->dst_reg];
if (BPF_CLASS(ins->code) == BPF_STX) {
rs = st->rv[ins->src_reg];
eval_apply_mask(&rs, msk);
} else
eval_fill_imm(&rs, msk, ins->imm);
err = eval_defined(NULL, &rs);
if (err != NULL)
return err;
err = eval_ptr(bvf, &rd, opsz, 1, ins->off);
if (err != NULL)
return err;
if (rd.v.type == BPF_ARG_PTR_STACK) {
sv = st->sv + rd.u.max / sizeof(uint64_t);
if (BPF_CLASS(ins->code) == BPF_STX &&
BPF_MODE(ins->code) == EBPF_XADD)
eval_max_bound(sv, msk);
else
*sv = rs;
/* pointer to mbuf */
} else if (rd.v.type == RTE_BPF_ARG_PTR_MBUF) {
err = eval_mbuf_store(&rd, opsz);
if (err != NULL)
return err;
}
return NULL;
}
static const char *
eval_func_arg(struct bpf_verifier *bvf, const struct rte_bpf_arg *arg,
struct bpf_reg_val *rv)
{
uint32_t i, n;
struct bpf_eval_state *st;
const char *err;
st = bvf->evst;
if (rv->v.type == RTE_BPF_ARG_UNDEF)
return "Undefined argument type";
if (arg->type != rv->v.type &&
arg->type != RTE_BPF_ARG_RAW &&
(arg->type != RTE_BPF_ARG_PTR ||
RTE_BPF_ARG_PTR_TYPE(rv->v.type) == 0))
return "Invalid argument type";
err = NULL;
/* argument is a pointer */
if (RTE_BPF_ARG_PTR_TYPE(arg->type) != 0) {
err = eval_ptr(bvf, rv, arg->size, 1, 0);
/*
* pointer to the variable on the stack is passed
* as an argument, mark stack space it occupies as initialized.
*/
if (err == NULL && rv->v.type == BPF_ARG_PTR_STACK) {
i = rv->u.max / sizeof(uint64_t);
n = i + arg->size / sizeof(uint64_t);
while (i != n) {
eval_fill_max_bound(st->sv + i, UINT64_MAX);
i++;
};
}
}
return err;
}
static const char *
eval_call(struct bpf_verifier *bvf, const struct ebpf_insn *ins)
{
uint32_t i, idx;
struct bpf_reg_val *rv;
const struct rte_bpf_xsym *xsym;
const char *err;
idx = ins->imm;
if (idx >= bvf->prm->nb_xsym ||
bvf->prm->xsym[idx].type != RTE_BPF_XTYPE_FUNC)
return "invalid external function index";
/* for now don't support function calls on 32 bit platform */
if (sizeof(uint64_t) != sizeof(uintptr_t))
return "function calls are supported only for 64 bit apps";
xsym = bvf->prm->xsym + idx;
/* evaluate function arguments */
err = NULL;
for (i = 0; i != xsym->func.nb_args && err == NULL; i++) {
err = eval_func_arg(bvf, xsym->func.args + i,
bvf->evst->rv + EBPF_REG_1 + i);
}
/* R1-R5 argument/scratch registers */
for (i = EBPF_REG_1; i != EBPF_REG_6; i++)
bvf->evst->rv[i].v.type = RTE_BPF_ARG_UNDEF;
/* update return value */
rv = bvf->evst->rv + EBPF_REG_0;