diff --git a/include/payload.h b/include/payload.h index 08e45f7f79e2..6685dad6f9f7 100644 --- a/include/payload.h +++ b/include/payload.h @@ -62,6 +62,8 @@ extern struct expr *payload_expr_join(const struct expr *e1, bool payload_expr_trim(struct expr *expr, struct expr *mask, const struct proto_ctx *ctx, unsigned int *shift); +bool payload_expr_trim_force(struct expr *expr, struct expr *mask, + unsigned int *shift); extern void payload_expr_expand(struct list_head *list, struct expr *expr, const struct proto_ctx *ctx); extern void payload_expr_complete(struct expr *expr, diff --git a/src/netlink_delinearize.c b/src/netlink_delinearize.c index 046e7a472b8d..86c8602860f6 100644 --- a/src/netlink_delinearize.c +++ b/src/netlink_delinearize.c @@ -2451,7 +2451,7 @@ static void binop_adjust(const struct expr *binop, struct expr *right, } } -static void __binop_postprocess(struct rule_pp_ctx *ctx, +static bool __binop_postprocess(struct rule_pp_ctx *ctx, struct expr *expr, struct expr *left, struct expr *mask, @@ -2501,17 +2501,27 @@ static void __binop_postprocess(struct rule_pp_ctx *ctx, expr_set_type(right, left->dtype, left->byteorder); expr_free(binop); + return true; + } else if (left->etype == EXPR_PAYLOAD && + expr->right->etype == EXPR_VALUE && + payload_expr_trim_force(left, mask, &shift)) { + mpz_rshift_ui(expr->right->value, shift); + *expr_binop = expr_get(left); + expr_free(binop); + return true; } + + return false; } -static void binop_postprocess(struct rule_pp_ctx *ctx, struct expr *expr, +static bool binop_postprocess(struct rule_pp_ctx *ctx, struct expr *expr, struct expr **expr_binop) { struct expr *binop = *expr_binop; struct expr *left = binop->left; struct expr *mask = binop->right; - __binop_postprocess(ctx, expr, left, mask, expr_binop); + return __binop_postprocess(ctx, expr, left, mask, expr_binop); } static void map_binop_postprocess(struct rule_pp_ctx *ctx, struct expr *expr) @@ -3178,6 +3188,7 @@ static void stmt_payload_binop_postprocess(struct rule_pp_ctx *ctx) switch (expr->left->etype) { case EXPR_BINOP: {/* I? */ + unsigned int shift = 0; mpz_t tmp; if (expr->op != OP_OR) @@ -3211,13 +3222,18 @@ static void stmt_payload_binop_postprocess(struct rule_pp_ctx *ctx) mpz_set(mask->value, bitmask); mpz_clear(bitmask); - binop_postprocess(ctx, expr, &expr->left); - if (!payload_is_known(payload)) { + if (!binop_postprocess(ctx, expr, &expr->left) && + !payload_is_known(payload) && + !payload_expr_trim_force(payload, + mask, &shift)) { mpz_set(mask->value, tmp); mpz_clear(tmp); return; } + if (shift) + mpz_rshift_ui(value->value, shift); + mpz_clear(tmp); expr_free(stmt->payload.expr); stmt->payload.expr = expr_get(payload); @@ -3237,6 +3253,7 @@ static void stmt_payload_binop_postprocess(struct rule_pp_ctx *ctx) switch (expr->op) { case OP_AND: { /* IIa */ + unsigned int shift_unused; mpz_t tmp; mpz_init(tmp); @@ -3248,7 +3265,8 @@ static void stmt_payload_binop_postprocess(struct rule_pp_ctx *ctx) mpz_clear(bitmask); stmt_payload_binop_pp(ctx, expr); - if (!payload_is_known(expr->left)) { + if (!payload_is_known(expr->left) && + !payload_expr_trim_force(expr->left, mask, &shift_unused)) { mpz_set(mask->value, tmp); mpz_clear(tmp); return; @@ -3260,6 +3278,7 @@ static void stmt_payload_binop_postprocess(struct rule_pp_ctx *ctx) * clear the payload expression. * The "mask" value becomes new stmt->payload.value * so set this to 0. + * Also the reason why &shift_unused is ignored. */ mpz_set_ui(mask->value, 0); break; diff --git a/src/payload.c b/src/payload.c index 44aa834cc07b..f8b192b5f2fa 100644 --- a/src/payload.c +++ b/src/payload.c @@ -1046,6 +1046,7 @@ static unsigned int mask_length(const struct expr *mask) * @expr: the payload expression * @mask: mask to use when searching templates * @ctx: protocol context + * @shift: shift adjustment to fix up RHS value * * Walk the template list and determine if a match can be found without * using the provided mask. @@ -1106,6 +1107,59 @@ bool payload_expr_trim(struct expr *expr, struct expr *mask, return false; } +/** + * payload_expr_trim_force - adjust payload len/offset according to mask + * + * @expr: the payload expression + * @mask: mask to use when searching templates + * @shift: shift adjustment to fix up RHS value + * + * Force-trim an unknown payload expression according to mask. + * + * This is only useful for unkown payload expressions that need + * to be printed in raw syntax (@base,offset,length). The kernel + * can only deal with byte-divisible offsets/length, e.g. @th,16,8. + * In such case we might be able to get rid of the mask. + * @base,offset,length & MASK OPERATOR VALUE then becomes + * @base,offset,length VALUE, where at least one of offset increases + * and length decreases. + * + * This function also returns the shift for the right hand + * constant side of the expression. + * + * @return: true if @expr was adjusted and mask can be discarded. + */ +bool payload_expr_trim_force(struct expr *expr, struct expr *mask, unsigned int *shift) +{ + unsigned int payload_offset = expr->payload.offset; + unsigned int mask_len = mask_length(mask); + unsigned int off, real_len; + + if (payload_is_known(expr) || expr->len <= mask_len) + return false; + + /* This provides the payload offset to use. + * mask->len is the total length of the mask, e.g. 16. + * mask_len holds the last bit number that will be zeroed, + */ + off = round_up(mask->len, BITS_PER_BYTE) - mask_len; + payload_offset += off; + + /* kernel only allows offsets <= 255 */ + if (round_up(payload_offset, BITS_PER_BYTE) > 255) + return false; + + real_len = mpz_popcount(mask->value); + if (real_len > expr->len) + return false; + + expr->payload.offset = payload_offset; + expr->len = real_len; + + *shift = mask_to_offset(mask); + return true; +} + /** * payload_expr_expand - expand raw merged adjacent payload expressions into its * original components