From e76bb379401816bbea773e73b524cd747324760a Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Tue, 7 Jul 2020 17:42:37 +0200 Subject: src: allow for variables in the log prefix string For example: define test = "state" define foo = "match" table x { chain y { ct state invalid log prefix "invalid $test $foo:" } } This patch scans for variables in the log prefix string. The log prefix expression is a list of constant and variable expression that are converted into a constant expression from the evaluation phase. Signed-off-by: Pablo Neira Ayuso --- src/evaluate.c | 49 ++++++++- src/parser_bison.y | 122 ++++++++++++++++++++- .../testcases/optionals/dumps/log_prefix_0.nft | 5 + tests/shell/testcases/optionals/log_prefix_0 | 16 +++ 4 files changed, 187 insertions(+), 5 deletions(-) create mode 100644 tests/shell/testcases/optionals/dumps/log_prefix_0.nft create mode 100755 tests/shell/testcases/optionals/log_prefix_0 diff --git a/src/evaluate.c b/src/evaluate.c index 640a7d46..d3368bac 100644 --- a/src/evaluate.c +++ b/src/evaluate.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include #include @@ -3203,8 +3204,50 @@ static int stmt_evaluate_queue(struct eval_ctx *ctx, struct stmt *stmt) return 0; } +static int stmt_evaluate_log_prefix(struct eval_ctx *ctx, struct stmt *stmt) +{ + char prefix[NF_LOG_PREFIXLEN] = {}, tmp[NF_LOG_PREFIXLEN] = {}; + int len = sizeof(prefix), offset = 0, ret; + struct expr *expr; + size_t size = 0; + + if (stmt->log.prefix->etype != EXPR_LIST) + return 0; + + list_for_each_entry(expr, &stmt->log.prefix->expressions, list) { + switch (expr->etype) { + case EXPR_VALUE: + expr_to_string(expr, tmp); + ret = snprintf(prefix + offset, len, "%s", tmp); + break; + case EXPR_VARIABLE: + ret = snprintf(prefix + offset, len, "%s", + expr->sym->expr->identifier); + break; + default: + BUG("unknown expresion type %s\n", expr_name(expr)); + break; + } + SNPRINTF_BUFFER_SIZE(ret, size, len, offset); + } + + if (len == NF_LOG_PREFIXLEN) + return stmt_error(ctx, stmt, "log prefix is too long"); + + expr_free(stmt->log.prefix); + + stmt->log.prefix = + constant_expr_alloc(&stmt->log.prefix->location, &string_type, + BYTEORDER_HOST_ENDIAN, + strlen(prefix) * BITS_PER_BYTE, + prefix); + return 0; +} + static int stmt_evaluate_log(struct eval_ctx *ctx, struct stmt *stmt) { + int ret = 0; + if (stmt->log.flags & (STMT_LOG_GROUP | STMT_LOG_SNAPLEN | STMT_LOG_QTHRESHOLD)) { if (stmt->log.flags & STMT_LOG_LEVEL) @@ -3218,7 +3261,11 @@ static int stmt_evaluate_log(struct eval_ctx *ctx, struct stmt *stmt) (stmt->log.flags & ~STMT_LOG_LEVEL || stmt->log.logflags)) return stmt_error(ctx, stmt, "log level audit doesn't support any further options"); - return 0; + + if (stmt->log.prefix) + ret = stmt_evaluate_log_prefix(ctx, stmt); + + return ret; } static int stmt_evaluate_set(struct eval_ctx *ctx, struct stmt *stmt) diff --git a/src/parser_bison.y b/src/parser_bison.y index 2fecc347..face9950 100644 --- a/src/parser_bison.y +++ b/src/parser_bison.y @@ -2636,11 +2636,125 @@ log_args : log_arg log_arg : PREFIX string { - struct expr *expr; + struct scope *scope = current_scope(state); + bool done = false, another_var = false; + char *start, *end, scratch = '\0'; + struct expr *expr, *item; + struct symbol *sym; + enum { + PARSE_TEXT, + PARSE_VAR, + } prefix_state; + + /* No variables in log prefix, skip. */ + if (!strchr($2, '$')) { + expr = constant_expr_alloc(&@$, &string_type, + BYTEORDER_HOST_ENDIAN, + (strlen($2) + 1) * BITS_PER_BYTE, $2); + $0->log.prefix = expr; + $0->log.flags |= STMT_LOG_PREFIX; + break; + } - expr = constant_expr_alloc(&@$, &string_type, - BYTEORDER_HOST_ENDIAN, - strlen($2) * BITS_PER_BYTE, $2); + /* Parse variables in log prefix string using a + * state machine parser with two states. This + * parser creates list of expressions composed + * of constant and variable expressions. + */ + expr = compound_expr_alloc(&@$, EXPR_LIST); + + start = (char *)$2; + + if (*start != '$') { + prefix_state = PARSE_TEXT; + } else { + prefix_state = PARSE_VAR; + start++; + } + end = start; + + /* Not nice, but works. */ + while (!done) { + switch (prefix_state) { + case PARSE_TEXT: + while (*end != '\0' && *end != '$') + end++; + + if (*end == '\0') + done = true; + + *end = '\0'; + item = constant_expr_alloc(&@$, &string_type, + BYTEORDER_HOST_ENDIAN, + (strlen(start) + 1) * BITS_PER_BYTE, + start); + compound_expr_add(expr, item); + + if (done) + break; + + start = end + 1; + end = start; + + /* fall through */ + case PARSE_VAR: + while (isalnum(*end) || *end == '_') + end++; + + if (*end == '\0') + done = true; + else if (*end == '$') + another_var = true; + else + scratch = *end; + + *end = '\0'; + + sym = symbol_get(scope, start); + if (!sym) { + sym = symbol_lookup_fuzzy(scope, start); + if (sym) { + erec_queue(error(&@2, "unknown identifier '%s'; " + "did you mean identifier ‘%s’?", + start, sym->identifier), + state->msgs); + } else { + erec_queue(error(&@2, "unknown identifier '%s'", + start), + state->msgs); + } + expr_free(expr); + xfree($2); + YYERROR; + } + item = variable_expr_alloc(&@$, scope, sym); + compound_expr_add(expr, item); + + if (done) + break; + + /* Restore original byte after + * symbol lookup. + */ + if (scratch) { + *end = scratch; + scratch = '\0'; + } + + start = end; + if (another_var) { + another_var = false; + start++; + prefix_state = PARSE_VAR; + } else { + prefix_state = PARSE_TEXT; + } + end = start; + break; + } + } + + xfree($2); $0->log.prefix = expr; $0->log.flags |= STMT_LOG_PREFIX; } diff --git a/tests/shell/testcases/optionals/dumps/log_prefix_0.nft b/tests/shell/testcases/optionals/dumps/log_prefix_0.nft new file mode 100644 index 00000000..8c11d697 --- /dev/null +++ b/tests/shell/testcases/optionals/dumps/log_prefix_0.nft @@ -0,0 +1,5 @@ +table ip x { + chain y { + ct state invalid log prefix "invalid state match, logging:" + } +} diff --git a/tests/shell/testcases/optionals/log_prefix_0 b/tests/shell/testcases/optionals/log_prefix_0 new file mode 100755 index 00000000..513a9e74 --- /dev/null +++ b/tests/shell/testcases/optionals/log_prefix_0 @@ -0,0 +1,16 @@ +#!/bin/bash + +set -e + +TMP=$(mktemp) + +RULESET='define test = "state" +define foo = "match, logging" + +table x { + chain y { + ct state invalid log prefix "invalid $test $foo:" + } +}' + +$NFT -f - <<< "$RULESET" -- cgit v1.2.3