From 1c7bcdff2cc8093d07f6214a24228b42e050aa23 Mon Sep 17 00:00:00 2001
From: Dapeng Gao <dapeng.gao@cl.cam.ac.uk>
Date: Sun, 8 Sep 2024 14:50:54 +0800
Subject: [PATCH] c18n: Override libsys's sigaction to directly call RTLD hook

Previously libsys's sigaction calls a libc function which in turn calls
the RTLD hook. This is broken but was undetected because c18n was
accidentally not enabled in the c18n-version of libsys.
---
 lib/libc/include/libc_private.h |  2 +-
 lib/libc/sys/sigaction.c        | 13 -------------
 lib/libsys/interposing_table.c  |  2 +-
 3 files changed, 2 insertions(+), 15 deletions(-)

diff --git a/lib/libc/include/libc_private.h b/lib/libc/include/libc_private.h
index 6a000c7fa6b9..6d8ed0496c64 100644
--- a/lib/libc/include/libc_private.h
+++ b/lib/libc/include/libc_private.h
@@ -396,7 +396,7 @@ int __strerror_rl(int errnum, char *strerrbuf, size_t buflen,
 
 #ifdef CHERI_LIB_C18N
 __pid_t		__sys_rfork(int);
-int	sigaction_c18n(int, const struct sigaction *, struct sigaction *);
+int	_rtld_sigaction(int, const struct sigaction *, struct sigaction *);
 #endif
 
 #endif /* _LIBC_PRIVATE_H_ */
diff --git a/lib/libc/sys/sigaction.c b/lib/libc/sys/sigaction.c
index 568dc7dc4526..809881ca4d3f 100644
--- a/lib/libc/sys/sigaction.c
+++ b/lib/libc/sys/sigaction.c
@@ -35,19 +35,6 @@
 
 __weak_reference(__sys_sigaction, __sigaction);
 __weak_reference(sigaction, __libc_sigaction);
-#ifdef CHERI_LIB_C18N
-/*
- * This weak symbol will always be resolved at runtime.
- */
-#pragma weak _rtld_sigaction
-int _rtld_sigaction(int, const struct sigaction *, struct sigaction *);
-
-int
-sigaction_c18n(int sig, const struct sigaction *act, struct sigaction *oact)
-{
-	return (_rtld_sigaction(sig, act, oact));
-}
-#endif
 
 #pragma weak sigaction
 int
diff --git a/lib/libsys/interposing_table.c b/lib/libsys/interposing_table.c
index 989aa6f75652..1b075d67ff2a 100644
--- a/lib/libsys/interposing_table.c
+++ b/lib/libsys/interposing_table.c
@@ -57,7 +57,7 @@ static interpos_func_t __libsys_interposing[INTERPOS_MAX] = {
 	SLOT(sendto, __sys_sendto),
 	SLOT(setcontext, __sys_setcontext),
 #ifdef CHERI_LIB_C18N
-	SLOT(sigaction, sigaction_c18n),
+	SLOT(sigaction, _rtld_sigaction),
 #else
 	SLOT(sigaction, __sys_sigaction),
 #endif