expr: bitwise: add support for kernel space AND, OR and XOR operations

Hitherto, the kernel has only supported boolean operations of the form:

  dst = (src & mask) ^ xor

where `src` is held in a register, and `mask` and `xor` are immediate
values.  User space has converted AND, OR and XOR operations to this
form, and so one operand has had to be immediate.  The kernel now
supports performing AND, OR and XOR operations directly, on one register
and an immediate value or on two registers, so we make that support
available to user space.

Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/libnftnl/expr.h b/include/libnftnl/expr.h
index fba1210622440969e61c5564851a840727a723ff..1c07b54139a57610b0031dba9744468236892f42 100644 (file)
--- a/include/libnftnl/expr.h
+++ b/include/libnftnl/expr.h
@@ -139,6 +139,7 @@ enum {
        NFTNL_EXPR_BITWISE_XOR,
        NFTNL_EXPR_BITWISE_OP,
        NFTNL_EXPR_BITWISE_DATA,
+       NFTNL_EXPR_BITWISE_SREG2,
        __NFTNL_EXPR_BITWISE_MAX
 };
 

diff --git a/src/expr/bitwise.c b/src/expr/bitwise.c
index 9385219a38b5dd90eae3776b06b7ed3af53e9dad..cac47a5500993079d0ab0a662a875cbe3e9b4661 100644 (file)
--- a/src/expr/bitwise.c
+++ b/src/expr/bitwise.c
@@ -19,6 +19,7 @@
 
 struct nftnl_expr_bitwise {
        enum nft_registers      sreg;
+       enum nft_registers      sreg2;
        enum nft_registers      dreg;
        enum nft_bitwise_ops    op;
        unsigned int            len;
@@ -37,6 +38,9 @@ nftnl_expr_bitwise_set(struct nftnl_expr *e, uint16_t type,
        case NFTNL_EXPR_BITWISE_SREG:
                memcpy(&bitwise->sreg, data, data_len);
                break;
+       case NFTNL_EXPR_BITWISE_SREG2:
+               memcpy(&bitwise->sreg2, data, sizeof(bitwise->sreg2));
+               break;
        case NFTNL_EXPR_BITWISE_DREG:
                memcpy(&bitwise->dreg, data, data_len);
                break;
@@ -66,6 +70,9 @@ nftnl_expr_bitwise_get(const struct nftnl_expr *e, uint16_t type,
        case NFTNL_EXPR_BITWISE_SREG:
                *data_len = sizeof(bitwise->sreg);
                return &bitwise->sreg;
+       case NFTNL_EXPR_BITWISE_SREG2:
+               *data_len = sizeof(bitwise->sreg2);
+               return &bitwise->sreg2;
        case NFTNL_EXPR_BITWISE_DREG:
                *data_len = sizeof(bitwise->dreg);
                return &bitwise->dreg;
@@ -98,6 +105,7 @@ static int nftnl_expr_bitwise_cb(const struct nlattr *attr, void *data)
 
        switch(type) {
        case NFTA_BITWISE_SREG:
+       case NFTA_BITWISE_SREG2:
        case NFTA_BITWISE_DREG:
        case NFTA_BITWISE_OP:
        case NFTA_BITWISE_LEN:
@@ -123,6 +131,8 @@ nftnl_expr_bitwise_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
 
        if (e->flags & (1 << NFTNL_EXPR_BITWISE_SREG))
                mnl_attr_put_u32(nlh, NFTA_BITWISE_SREG, htonl(bitwise->sreg));
+       if (e->flags & (1 << NFTNL_EXPR_BITWISE_SREG2))
+               mnl_attr_put_u32(nlh, NFTA_BITWISE_SREG2, htonl(bitwise->sreg2));
        if (e->flags & (1 << NFTNL_EXPR_BITWISE_DREG))
                mnl_attr_put_u32(nlh, NFTA_BITWISE_DREG, htonl(bitwise->dreg));
        if (e->flags & (1 << NFTNL_EXPR_BITWISE_OP))
@@ -169,6 +179,10 @@ nftnl_expr_bitwise_parse(struct nftnl_expr *e, struct nlattr *attr)
                bitwise->sreg = ntohl(mnl_attr_get_u32(tb[NFTA_BITWISE_SREG]));
                e->flags |= (1 << NFTNL_EXPR_BITWISE_SREG);
        }
+       if (tb[NFTA_BITWISE_SREG2]) {
+               bitwise->sreg2 = ntohl(mnl_attr_get_u32(tb[NFTA_BITWISE_SREG2]));
+               e->flags |= (1 << NFTNL_EXPR_BITWISE_SREG2);
+       }
        if (tb[NFTA_BITWISE_DREG]) {
                bitwise->dreg = ntohl(mnl_attr_get_u32(tb[NFTA_BITWISE_DREG]));
                e->flags |= (1 << NFTNL_EXPR_BITWISE_DREG);
@@ -240,6 +254,31 @@ nftnl_expr_bitwise_snprintf_shift(char *buf, size_t remain, const char *op,
        return offset;
 }
 
+static int
+nftnl_expr_bitwise_snprintf_bool(char *buf, size_t remain, const char *op,
+                                const struct nftnl_expr *e,
+                                const struct nftnl_expr_bitwise *bitwise)
+{
+       int offset = 0, ret;
+
+       ret = snprintf(buf, remain, "reg %u = ( reg %u %s ",
+                      bitwise->dreg, bitwise->sreg, op);
+       SNPRINTF_BUFFER_SIZE(ret, remain, offset);
+
+       if (e->flags & (1 << NFTNL_EXPR_BITWISE_SREG2))
+               ret = snprintf(buf + offset, remain, "reg %u ", bitwise->sreg2);
+       else
+               ret = nftnl_data_reg_snprintf(buf + offset, remain,
+                                             &bitwise->data,
+                                             0, DATA_VALUE);
+       SNPRINTF_BUFFER_SIZE(ret, remain, offset);
+
+       ret = snprintf(buf + offset, remain, ") ");
+       SNPRINTF_BUFFER_SIZE(ret, remain, offset);
+
+       return offset;
+}
+
 static int
 nftnl_expr_bitwise_snprintf(char *buf, size_t size,
                            uint32_t flags, const struct nftnl_expr *e)
@@ -252,10 +291,24 @@ nftnl_expr_bitwise_snprintf(char *buf, size_t size,
                err = nftnl_expr_bitwise_snprintf_mask_xor(buf, size, bitwise);
                break;
        case NFT_BITWISE_LSHIFT:
-               err = nftnl_expr_bitwise_snprintf_shift(buf, size, "<<", bitwise);
+               err = nftnl_expr_bitwise_snprintf_shift(buf, size, "<<",
+                                                       bitwise);
                break;
        case NFT_BITWISE_RSHIFT:
-               err = nftnl_expr_bitwise_snprintf_shift(buf, size, ">>", bitwise);
+               err = nftnl_expr_bitwise_snprintf_shift(buf, size, ">>",
+                                                       bitwise);
+               break;
+       case NFT_BITWISE_AND:
+               err = nftnl_expr_bitwise_snprintf_bool(buf, size, "&", e,
+                                                      bitwise);
+               break;
+       case NFT_BITWISE_OR:
+               err = nftnl_expr_bitwise_snprintf_bool(buf, size, "|", e,
+                                                      bitwise);
+               break;
+       case NFT_BITWISE_XOR:
+               err = nftnl_expr_bitwise_snprintf_bool(buf, size, "^", e,
+                                                      bitwise);
                break;
        }