[PATCH 3/3] MEDIUM: lua: expose safe fetch/conv via val_args_flags

[Robin H. Johnson]

Any val_args functions with side-effects is unsafe for use in the Lua
context, and previously this stopped them from having object methods
created except where explicitly whitelisted (val_payload_lv, val_hdr).

Using the new val_args_flags field, we can track which sample
fetches/converters are safe, without having to explicitly whitelist in
the lua codebase.

Before any val_args function is used, the val_args_flags field is
checked as an additional safety measure.

The following fetch/converters are now available from Lua:
- 51d.all (51d_all)
- 51d.single (51d_all)
- distcc_body
- distcc_param
- bool
- meth
- json
- field
- word
- regsub

Initial-Discovery: Yue Zhu <y...@digitalocean.com>
Signed-off-by: Robin H. Johnson <robb...@gentoo.org>
Signed-off-by: Robin H. Johnson <rjohn...@digitalocean.com>
---
 src/hlua.c | 28 +++++++++++++++++++---------
 1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/src/hlua.c b/src/hlua.c
index a9d126b53..6ddfed4b3 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -3299,9 +3299,14 @@ __LJMP static int hlua_run_sample_fetch(lua_State *L)
        MAY_LJMP(hlua_lua2arg_check(L, 2, args, f->arg_mask, hsmp->p));
 
        /* Run the special args checker. */
-       if (f->val_args && !f->val_args(args, NULL)) {
-               lua_pushfstring(L, "error in arguments");
-               WILL_LJMP(lua_error(L));
+       if (f->val_args) {
+               if (unlikely(f->val_args_flags != SMP_VAL_ARGS_F_SAFE)) {
+                       lua_pushfstring(L, "argument validation is unsafe");
+                       WILL_LJMP(lua_error(L));
+               } else if(!f->val_args(args, NULL)) {
+                       lua_pushfstring(L, "error in arguments");
+                       WILL_LJMP(lua_error(L));
+               }
        }
 
        /* Initialise the sample. */
@@ -3405,9 +3410,14 @@ __LJMP static int hlua_run_sample_conv(lua_State *L)
        MAY_LJMP(hlua_lua2arg_check(L, 3, args, conv->arg_mask, hsmp->p));
 
        /* Run the special args checker. */
-       if (conv->val_args && !conv->val_args(args, conv, "", 0, NULL)) {
-               hlua_pusherror(L, "error in arguments");
-               WILL_LJMP(lua_error(L));
+       if (conv->val_args) {
+               if (unlikely(conv->val_args_flags != SMP_VAL_ARGS_F_SAFE)) {
+                       lua_pushfstring(L, "argument validation is unsafe");
+                       WILL_LJMP(lua_error(L));
+               } else if (!conv->val_args(args, conv, "", 0, NULL)) {
+                       hlua_pusherror(L, "error in arguments");
+                       WILL_LJMP(lua_error(L));
+               }
        }
 
        /* Initialise the sample. */
@@ -7668,8 +7678,7 @@ void hlua_init(void)
                 * not safe during the runtime.
                 */
                if ((sf->val_args != NULL) &&
-                   (sf->val_args != val_payload_lv) &&
-                        (sf->val_args != val_hdr))
+                       (sf->val_args_flags != SMP_VAL_ARGS_F_SAFE))
                        continue;
 
                /* gL.Tua doesn't support '.' and '-' in the function names, 
replace it
@@ -7714,7 +7723,8 @@ void hlua_init(void)
                /* Dont register the keywork if the arguments check function are
                 * not safe during the runtime.
                 */
-               if (sc->val_args != NULL)
+               if ((sc->val_args != NULL) &&
+                       (sc->val_args_flags != SMP_VAL_ARGS_F_SAFE))
                        continue;
 
                /* gL.Tua doesn't support '.' and '-' in the function names, 
replace it
-- 
2.18.0