2 files changed, 59 insertions, 8 deletions

diff --git a/libexec/rtld-elf/Symbol.map b/libexec/rtld-elf/Symbol.map
index 0b7ad63f60a7..3cdbb30d04a0 100644
--- a/libexec/rtld-elf/Symbol.map
+++ b/libexec/rtld-elf/Symbol.map
@@ -21,6 +21,11 @@ FBSD_1.3 {
     fdlopen;
 };
 
+FBSD_1.8 {
+    rtld_get_var;
+    rtld_set_var;
+};
+
 FBSDprivate_1.0 {
     _rtld_thread_init;
     _rtld_allocate_tls;
diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c
index 7c61fec44ef7..f1075bc75d5f 100644
--- a/libexec/rtld-elf/rtld.c
+++ b/libexec/rtld-elf/rtld.c
@@ -257,6 +257,8 @@ int _rtld_addr_phdr(const void *, struct dl_phdr_info *) __exported;
 int _rtld_get_stack_prot(void) __exported;
 int _rtld_is_dlopened(void *) __exported;
 void _rtld_error(const char *, ...) __exported;
+const char *rtld_get_var(const char *name) __exported;
+int rtld_set_var(const char *name, const char *val) __exported;
 
 /* Only here to fix -Wmissing-prototypes warnings */
 int __getosreldate(void);
@@ -347,31 +349,35 @@ struct ld_env_var_desc {
 	const char * const n;
 	const char *val;
 	const bool unsecure:1;
+	const bool can_update:1;
+	const bool debug:1;
+	bool owned:1;
 };
 #define LD_ENV_DESC(var, unsec, ...)		\
 	[LD_##var] = {				\
 	    .n = #var,				\
 	    .unsecure = unsec,			\
 	    __VA_ARGS__				\
+	}
 
 static struct ld_env_var_desc ld_env_vars[] = {
 	LD_ENV_DESC(BIND_NOW, false),
 	LD_ENV_DESC(PRELOAD, true),
 	LD_ENV_DESC(LIBMAP, true),
-	LD_ENV_DESC(LIBRARY_PATH, true),
-	LD_ENV_DESC(LIBRARY_PATH_FDS, true),
+	LD_ENV_DESC(LIBRARY_PATH, true, .can_update = true),
+	LD_ENV_DESC(LIBRARY_PATH_FDS, true, .can_update = true),
 	LD_ENV_DESC(LIBMAP_DISABLE, true),
 	LD_ENV_DESC(BIND_NOT, true),
-	LD_ENV_DESC(DEBUG, true),
+	LD_ENV_DESC(DEBUG, true, .can_update = true, .debug = true),
 	LD_ENV_DESC(ELF_HINTS_PATH, true),
 	LD_ENV_DESC(LOADFLTR, true),
-	LD_ENV_DESC(LIBRARY_PATH_RPATH, true),
+	LD_ENV_DESC(LIBRARY_PATH_RPATH, true, .can_update = true),
 	LD_ENV_DESC(PRELOAD_FDS, true),
-	LD_ENV_DESC(DYNAMIC_WEAK, true),
+	LD_ENV_DESC(DYNAMIC_WEAK, true, .can_update = true),
 	LD_ENV_DESC(TRACE_LOADED_OBJECTS, false),
-	LD_ENV_DESC(UTRACE, false),
-	LD_ENV_DESC(DUMP_REL_PRE, false),
-	LD_ENV_DESC(DUMP_REL_POST, false),
+	LD_ENV_DESC(UTRACE, false, .can_update = true),
+	LD_ENV_DESC(DUMP_REL_PRE, false, .can_update = true),
+	LD_ENV_DESC(DUMP_REL_POST, false, .can_update = true),
 	LD_ENV_DESC(TRACE_LOADED_OBJECTS_PROGNAME, false),
 	LD_ENV_DESC(TRACE_LOADED_OBJECTS_FMT1, false),
 	LD_ENV_DESC(TRACE_LOADED_OBJECTS_FMT2, false),
@@ -6329,6 +6335,46 @@ dump_auxv(Elf_Auxinfo **aux_info)
 	}
 }
 
+const char *
+rtld_get_var(const char *name)
+{
+	const struct ld_env_var_desc *lvd;
+	u_int i;
+
+	for (i = 0; i < nitems(ld_env_vars); i++) {
+		lvd = &ld_env_vars[i];
+		if (strcmp(lvd->n, name) == 0)
+			return (lvd->val);
+	}
+	return (NULL);
+}
+
+int
+rtld_set_var(const char *name, const char *val)
+{
+	struct ld_env_var_desc *lvd;
+	u_int i;
+
+	for (i = 0; i < nitems(ld_env_vars); i++) {
+		lvd = &ld_env_vars[i];
+		if (strcmp(lvd->n, name) != 0)
+			continue;
+		if (!lvd->can_update || (lvd->unsecure && !trust))
+			return (EPERM);
+		if (lvd->owned)
+			free(__DECONST(char *, lvd->val));
+		if (val != NULL)
+			lvd->val = xstrdup(val);
+		else
+			lvd->val = NULL;
+		lvd->owned = true;
+		if (lvd->debug)
+			debug = lvd->val != NULL && *lvd->val != '\0';
+		return (0);
+	}
+	return (ENOENT);
+}
+
 /*
  * Overrides for libc_pic-provided functions.
  */