login: clear dangerous environment variables if started by non-root

1 files changed, 26 insertions, 0 deletions

diff --git a/libbb/login.c b/libbb/login.c
index 308e1bfed..1af3165b9 100644
--- a/libbb/login.c
+++ b/libbb/login.c
@@ -99,3 +99,29 @@ void print_login_prompt(void)
         fputs(LOGIN, stdout);
         fflush(stdout);
 }
+
+/* Clear dangerous stuff, set PATH */
+static const char forbid[] ALIGN1 =
+        "ENV" "\0"
+        "BASH_ENV" "\0"
+        "HOME" "\0"
+        "IFS" "\0"
+        "SHELL" "\0"
+        "LD_LIBRARY_PATH" "\0"
+        "LD_PRELOAD" "\0"
+        "LD_TRACE_LOADED_OBJECTS" "\0"
+        "LD_BIND_NOW" "\0"
+        "LD_AOUT_LIBRARY_PATH" "\0"
+        "LD_AOUT_PRELOAD" "\0"
+        "LD_NOWARN" "\0"
+        "LD_KEEPDIR" "\0";
+
+void sanitize_env_for_suid(void)
+{
+        const char *p = forbid;
+        do {
+                unsetenv(p);
+                p += strlen(p) + 1;
+        } while (*p);
+        putenv((char*)bb_PATH_root_path);
+}