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bifcl: Render runtime type checks for var_args bifs

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Currently, Zeek disables any static type checking for var_arg bifs.
However, the generated preamble for var_args bifs assume that
typed positional arguments are correctly typed and blindly calls
the type converters on them. This easily triggers abort()s at runtime
currently when a script mistakenly uses the wrong types for var_arg
bifs. For example, calling publish_rr() with a port instead of a string
causes a hard-abort with Zeek 5.0.8.

    $ zeek -e 'Cluster::publish_rr(Cluster::Pool(), 80/tcp)'
    fatal error in <no location>: Val::CONVERTER (port/string) (80/tcp)
    Aborted (core dumped)

Extend bifcl so that for var_arg functions and the types that bifcl understands,
we render a runtime type check and explicit early return to avoid the abort().
For any/other types, the implementer of the bif continuous to be responsible
for type checking.

This isn't solving the var_args situation generally, but avoids some
ad-hoc fixes trickling in current bif implementations.

Some references:

https://github.com/zeek/zeek/issues/1523
https://github.com/zeek/zeek/issues/2425
https://github.com/zeek/zeek/issues/2935
https://github.com/zeek/zeek/pull/2950
This commit is contained in:
Arne Welzel 2023-04-19 14:15:09 +02:00 • committed by Tim Wojtulewicz
parent efb32d31fc
commit e7cce57f2b
3 changed files with 26 additions and 9 deletions
Download patch file Download diff file Expand all files Collapse all files

23
tools/bifcl/bif_arg.cc
View file

@ -9,6 +9,7 @@ using namespace std;
static struct
{
const char* type_enum;
const char* bif_type;
const char* zeek_type;
const char* c_type;
@ -21,8 +22,8 @@ static struct
} builtin_func_arg_type[] = {
#define DEFINE_BIF_TYPE(id, bif_type, zeek_type, c_type, c_type_smart, accessor, accessor_smart, \
cast_smart, constructor, ctor_smart) \
{bif_type, zeek_type, c_type, c_type_smart, accessor, \
accessor_smart, cast_smart, constructor, ctor_smart},
{#id, bif_type, zeek_type, c_type, c_type_smart, \
accessor, accessor_smart, cast_smart, constructor, ctor_smart},
#include "bif_type.def"
#undef DEFINE_BIF_TYPE
};
@ -58,8 +59,24 @@ void BuiltinFuncArg::PrintZeek(FILE* fp)
fprintf(fp, "%s: %s%s %s", name, builtin_func_arg_type[type].zeek_type, type_str, attr_str);
}
void BuiltinFuncArg::PrintCDef(FILE* fp, int n)
void BuiltinFuncArg::PrintCDef(FILE* fp, int n, bool runtime_type_check)
{
// Generate a runtime type-check pre-amble for types we understand
if ( runtime_type_check && type != TYPE_OTHER && type != TYPE_ANY )
{
fprintf(fp, "\t\t{\n");
fprintf(fp, "\t\t// Runtime type check for %s argument\n", name);
fprintf(fp, "\t\tzeek::TypeTag __tag = (*%s)[%d]->GetType()->Tag();\n", arg_list_name, n);
fprintf(fp, "\t\tif ( __tag != %s )\n", builtin_func_arg_type[type].type_enum);
fprintf(fp, "\t\t\t{\n");
fprintf(fp,
"\t\t\tzeek::emit_builtin_error(zeek::util::fmt(\"expected type %s for %s, got "
"%%s\", zeek::type_name(__tag)));\n",
builtin_func_arg_type[type].zeek_type, name);
fprintf(fp, "\t\t\treturn nullptr;\n");
fprintf(fp, "\t\t\t}\n");
fprintf(fp, "\t\t}\n");
}
fprintf(fp, "\t%s %s = (%s) (", builtin_func_arg_type[type].c_type, name,
builtin_func_arg_type[type].c_type);

10
tools/bifcl/builtin-func.y
View file

@ -708,8 +708,8 @@ body_start: TOK_LPB c_code_begin
fprintf(fp_func_def, "\tif ( %s->size() != %d )\n", arg_list_name, argc);
fprintf(fp_func_def, "\t\t{\n");
fprintf(fp_func_def,
"\t\treporter->Error(\"%s() takes exactly %d argument(s)\");\n",
decl.zeek_fullname.c_str(), argc);
"\t\tzeek::emit_builtin_error(zeek::util::fmt(\"%s() takes exactly %d argument(s), got %%lu\", %s->size()));\n",
decl.zeek_fullname.c_str(), argc, arg_list_name);
fprintf(fp_func_def, "\t\treturn nullptr;\n");
fprintf(fp_func_def, "\t\t}\n");
}
@ -718,14 +718,14 @@ body_start: TOK_LPB c_code_begin
fprintf(fp_func_def, "\tif ( %s->size() < %d )\n", arg_list_name, argc);
fprintf(fp_func_def, "\t\t{\n");
fprintf(fp_func_def,
"\t\treporter->Error(\"%s() takes at least %d argument(s)\");\n",
decl.zeek_fullname.c_str(), argc);
"\t\tzeek::emit_builtin_error(zeek::util::fmt(\"%s() takes at least %d argument(s), got %%lu\", %s->size()));\n",
decl.zeek_fullname.c_str(), argc, arg_list_name);
fprintf(fp_func_def, "\t\treturn nullptr;\n");
fprintf(fp_func_def, "\t\t}\n");
}
for ( int i = 0; i < (int) args.size(); ++i )
args[i]->PrintCDef(fp_func_def, i + implicit_arg);
args[i]->PrintCDef(fp_func_def, i + implicit_arg, var_arg);
print_line_directive(fp_func_def);
}
;

2
tools/bifcl/include/bif_arg.h
View file

@ -25,7 +25,7 @@ public:
int Type() const { return type; }
void PrintZeek(FILE* fp);
void PrintCDef(FILE* fp, int n);
void PrintCDef(FILE* fp, int n, bool runtime_type_check = false);
void PrintCArg(FILE* fp, int n);
void PrintValConstructor(FILE* fp);