svn commit: r361073 - in head: include lib/libc/gen libexec/rtld-elf

[Konstantin Belousov]

Author: kib
Date: Fri May 15 11:58:01 2020
New Revision: 361073
URL: https://svnweb.freebsd.org/changeset/base/361073

Log:
  Implement RTLD_DEEPBIND.
  
  PR:	246462
  Tested by:	Martin Birgmeier <d8zNeCFG at aon.at>
  Sponsored by:	The FreeBSD Foundation
  MFC after:	1 week
  Differential revision:	https://reviews.freebsd.org/D24841

Modified:
  head/include/dlfcn.h
  head/lib/libc/gen/dlopen.3
  head/libexec/rtld-elf/rtld.c
  head/libexec/rtld-elf/rtld.h

Modified: head/include/dlfcn.h
==============================================================================
--- head/include/dlfcn.h	Fri May 15 11:03:27 2020	(r361072)
+++ head/include/dlfcn.h	Fri May 15 11:58:01 2020	(r361073)
@@ -47,6 +47,8 @@
 #define	RTLD_TRACE	0x200	/* Trace loaded objects and exit. */
 #define	RTLD_NODELETE	0x01000	/* Do not remove members. */
 #define	RTLD_NOLOAD	0x02000	/* Do not load if not already loaded. */
+#define	RTLD_DEEPBIND	0x04000	/* Put symbols from the dso ahead of
+				   the global list */
 
 /*
  * Request arguments for dlinfo().

Modified: head/lib/libc/gen/dlopen.3
==============================================================================
--- head/lib/libc/gen/dlopen.3	Fri May 15 11:03:27 2020	(r361072)
+++ head/lib/libc/gen/dlopen.3	Fri May 15 11:58:01 2020	(r361073)
@@ -32,7 +32,7 @@
 .\" @(#) dlopen.3 1.6 90/01/31 SMI
 .\" $FreeBSD$
 .\"
-.Dd January 2, 2019
+.Dd May 14, 2020
 .Dt DLOPEN 3
 .Os
 .Sh NAME
@@ -162,6 +162,9 @@ the process address space, otherwise
 is returned.
 Other mode flags may be specified, which will be applied for promotion
 for the found object.
+.It Dv RTLD_DEEPBIND
+Symbols from the loaded library are put before global symbols when
+resolving symbolic references originated from the library.
 .El
 .Pp
 If

Modified: head/libexec/rtld-elf/rtld.c
==============================================================================
--- head/libexec/rtld-elf/rtld.c	Fri May 15 11:03:27 2020	(r361072)
+++ head/libexec/rtld-elf/rtld.c	Fri May 15 11:58:01 2020	(r361073)
@@ -3366,6 +3366,8 @@ rtld_dlopen(const char *name, int fd, int mode)
 	    lo_flags |= RTLD_LO_NODELETE;
     if (mode & RTLD_NOLOAD)
 	    lo_flags |= RTLD_LO_NOLOAD;
+    if (mode & RTLD_DEEPBIND)
+	    lo_flags |= RTLD_LO_DEEPBIND;
     if (ld_tracing != NULL)
 	    lo_flags |= RTLD_LO_TRACE | RTLD_LO_IGNSTLS;
 
@@ -3417,6 +3419,8 @@ dlopen_object(const char *name, int fd, Obj_Entry *ref
 	if (globallist_next(old_obj_tail) != NULL) {
 	    /* We loaded something new. */
 	    assert(globallist_next(old_obj_tail) == obj);
+	    if ((lo_flags & RTLD_LO_DEEPBIND) != 0)
+		obj->symbolic = true;
 	    result = 0;
 	    if ((lo_flags & (RTLD_LO_EARLY | RTLD_LO_IGNSTLS)) == 0 &&
 	      obj->static_tls && !allocate_tls_offset(obj)) {

Modified: head/libexec/rtld-elf/rtld.h
==============================================================================
--- head/libexec/rtld-elf/rtld.h	Fri May 15 11:03:27 2020	(r361072)
+++ head/libexec/rtld-elf/rtld.h	Fri May 15 11:58:01 2020	(r361073)
@@ -309,6 +309,7 @@ TAILQ_HEAD(obj_entry_q, Struct_Obj_Entry);
 #define	RTLD_LO_EARLY	0x20	/* Do not call ctors, postpone it to the
 				   initialization during the image start. */
 #define	RTLD_LO_IGNSTLS 0x40	/* Do not allocate static TLS */
+#define	RTLD_LO_DEEPBIND 0x80	/* Force symbolic for this object */
 
 /*
  * Symbol cache entry used during relocation to avoid multiple lookups