[PATCH 3/3] ldso: support RTLD_NOLOAD
Timo Teräs
timo.teras at iki.fi
Fri Mar 18 13:36:59 UTC 2011
So application query if specified modile is loaded or not with
dlopen.
Signed-off-by: Timo Teräs <timo.teras at iki.fi>
---
ldso/include/dl-elf.h | 6 ++++--
ldso/ldso/dl-elf.c | 30 +++++++++++++++++-------------
ldso/ldso/ldso.c | 4 +++-
ldso/libdl/libdl.c | 5 +++--
libc/sysdeps/linux/common/bits/dlfcn.h | 4 ++--
5 files changed, 29 insertions(+), 20 deletions(-)
diff --git a/ldso/include/dl-elf.h b/ldso/include/dl-elf.h
index 7fbb373..7102351 100644
--- a/ldso/include/dl-elf.h
+++ b/ldso/include/dl-elf.h
@@ -25,16 +25,18 @@ static __inline__ void _dl_map_cache(void) { }
static __inline__ void _dl_unmap_cache(void) { }
#endif
+#define DL_RESOLVE_SECURE 0x0001
+#define DL_RESOLVE_NOLOAD 0x0002
/* Function prototypes for non-static stuff in readelflib1.c */
extern void _dl_parse_lazy_relocation_information(struct dyn_elf *rpnt,
unsigned long rel_addr, unsigned long rel_size);
extern int _dl_parse_relocation_information(struct dyn_elf *rpnt,
unsigned long rel_addr, unsigned long rel_size);
-extern struct elf_resolve * _dl_load_shared_library(int secure,
+extern struct elf_resolve * _dl_load_shared_library(int resolve_flags,
struct dyn_elf **rpnt, struct elf_resolve *tpnt, char *full_libname,
int trace_loaded_objects);
-extern struct elf_resolve * _dl_load_elf_shared_library(int secure,
+extern struct elf_resolve * _dl_load_elf_shared_library(int resolve_flags,
struct dyn_elf **rpnt, char *libname);
extern struct elf_resolve *_dl_check_if_named_library_is_loaded(const char *full_libname,
int trace_loaded_objects);
diff --git a/ldso/ldso/dl-elf.c b/ldso/ldso/dl-elf.c
index 2b2d429..6d35bf2 100644
--- a/ldso/ldso/dl-elf.c
+++ b/ldso/ldso/dl-elf.c
@@ -132,7 +132,7 @@ _dl_protect_relro (struct elf_resolve *l)
/* This function's behavior must exactly match that
* in uClibc/ldso/util/ldd.c */
static struct elf_resolve *
-search_for_named_library(const char *name, int secure, const char *path_list,
+search_for_named_library(const char *name, int resolve_flags, const char *path_list,
struct dyn_elf **rpnt, const char *origin)
{
char *mylibname;
@@ -162,7 +162,7 @@ search_for_named_library(const char *name, int secure, const char *path_list,
if (plen >= 7 && _dl_memcmp(p, "$ORIGIN", 7) == 0) {
int olen;
- if (secure && plen != 7)
+ if ((resolve_flags & DL_RESOLVE_SECURE) && plen != 7)
continue;
if (origin == NULL)
continue;
@@ -182,7 +182,7 @@ search_for_named_library(const char *name, int secure, const char *path_list,
_dl_strcat(mylibname, "/");
_dl_strcat(mylibname, name);
- tpnt = _dl_load_elf_shared_library(secure, rpnt, mylibname);
+ tpnt = _dl_load_elf_shared_library(resolve_flags, rpnt, mylibname);
if (tpnt != NULL)
return tpnt;
}
@@ -194,7 +194,7 @@ search_for_named_library(const char *name, int secure, const char *path_list,
unsigned long _dl_error_number;
unsigned long _dl_internal_error_number;
-struct elf_resolve *_dl_load_shared_library(int secure, struct dyn_elf **rpnt,
+struct elf_resolve *_dl_load_shared_library(int resolve_flags, struct dyn_elf **rpnt,
struct elf_resolve *tpnt, char *full_libname, int attribute_unused trace_loaded_objects)
{
char *pnt;
@@ -223,7 +223,7 @@ struct elf_resolve *_dl_load_shared_library(int secure, struct dyn_elf **rpnt,
if (libname != full_libname) {
_dl_if_debug_dprint("\ttrying file='%s'\n", full_libname);
- tpnt1 = _dl_load_elf_shared_library(secure, rpnt, full_libname);
+ tpnt1 = _dl_load_elf_shared_library(resolve_flags, rpnt, full_libname);
if (tpnt1) {
return tpnt1;
}
@@ -238,7 +238,7 @@ struct elf_resolve *_dl_load_shared_library(int secure, struct dyn_elf **rpnt,
if (pnt) {
pnt += (unsigned long) tpnt->dynamic_info[DT_STRTAB];
_dl_if_debug_dprint("\tsearching RPATH='%s'\n", pnt);
- if ((tpnt1 = search_for_named_library(libname, secure, pnt, rpnt,
+ if ((tpnt1 = search_for_named_library(libname, resolve_flags, pnt, rpnt,
tpnt->libname)) != NULL)
return tpnt1;
}
@@ -247,7 +247,7 @@ struct elf_resolve *_dl_load_shared_library(int secure, struct dyn_elf **rpnt,
/* Check in LD_{ELF_}LIBRARY_PATH, if specified and allowed */
if (_dl_library_path) {
_dl_if_debug_dprint("\tsearching LD_LIBRARY_PATH='%s'\n", _dl_library_path);
- if ((tpnt1 = search_for_named_library(libname, secure, _dl_library_path, rpnt, NULL)) != NULL)
+ if ((tpnt1 = search_for_named_library(libname, resolve_flags, _dl_library_path, rpnt, NULL)) != NULL)
{
return tpnt1;
}
@@ -261,7 +261,7 @@ struct elf_resolve *_dl_load_shared_library(int secure, struct dyn_elf **rpnt,
if (pnt) {
pnt += (unsigned long) tpnt->dynamic_info[DT_STRTAB];
_dl_if_debug_dprint("\tsearching RUNPATH='%s'\n", pnt);
- if ((tpnt1 = search_for_named_library(libname, secure, pnt, rpnt, NULL)) != NULL)
+ if ((tpnt1 = search_for_named_library(libname, resolve_flags, pnt, rpnt, NULL)) != NULL)
return tpnt1;
}
#endif
@@ -284,7 +284,7 @@ struct elf_resolve *_dl_load_shared_library(int secure, struct dyn_elf **rpnt,
|| libent[i].flags == LIB_ELF_LIBC0
|| libent[i].flags == LIB_ELF_LIBC5)
&& _dl_strcmp(libname, strs + libent[i].sooffset) == 0
- && (tpnt1 = _dl_load_elf_shared_library(secure, rpnt, strs + libent[i].liboffset))
+ && (tpnt1 = _dl_load_elf_shared_library(resolve_flags, rpnt, strs + libent[i].liboffset))
) {
return tpnt1;
}
@@ -295,14 +295,14 @@ struct elf_resolve *_dl_load_shared_library(int secure, struct dyn_elf **rpnt,
/* Look for libraries wherever the shared library loader
* was installed */
_dl_if_debug_dprint("\tsearching ldso dir='%s'\n", _dl_ldsopath);
- tpnt1 = search_for_named_library(libname, secure, _dl_ldsopath, rpnt, NULL);
+ tpnt1 = search_for_named_library(libname, resolve_flags, _dl_ldsopath, rpnt, NULL);
if (tpnt1 != NULL)
return tpnt1;
/* Lastly, search the standard list of paths for the library.
This list must exactly match the list in uClibc/ldso/util/ldd.c */
_dl_if_debug_dprint("\tsearching full lib path list\n");
- tpnt1 = search_for_named_library(libname, secure,
+ tpnt1 = search_for_named_library(libname, resolve_flags,
UCLIBC_RUNTIME_PREFIX "lib:"
UCLIBC_RUNTIME_PREFIX "usr/lib"
#ifndef __LDSO_CACHE_SUPPORT__
@@ -329,7 +329,7 @@ goof:
* are required.
*/
-struct elf_resolve *_dl_load_elf_shared_library(int secure,
+struct elf_resolve *_dl_load_elf_shared_library(int resolve_flags,
struct dyn_elf **rpnt, char *libname)
{
ElfW(Ehdr) *epnt;
@@ -368,7 +368,7 @@ struct elf_resolve *_dl_load_elf_shared_library(int secure,
}
/* If we are in secure mode (i.e. a setu/gid binary using LD_PRELOAD),
we don't load the library if it isn't setuid. */
- if (secure) {
+ if (resolve_flags & DL_RESOLVE_SECURE) {
if (!(st.st_mode & S_ISUID)) {
_dl_close(infile);
return NULL;
@@ -384,6 +384,10 @@ struct elf_resolve *_dl_load_elf_shared_library(int secure,
return tpnt;
}
}
+ if (resolve_flags & DL_RESOLVE_NOLOAD) {
+ _dl_close(infile);
+ return NULL;
+ }
header = _dl_mmap((void *) 0, _dl_pagesize, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_UNINITIALIZE, -1, 0);
if (_dl_mmap_check_error(header)) {
diff --git a/ldso/ldso/ldso.c b/ldso/ldso/ldso.c
index 9423670..b71af34 100644
--- a/ldso/ldso/ldso.c
+++ b/ldso/ldso/ldso.c
@@ -646,7 +646,9 @@ void _dl_get_ready_to_run(struct elf_resolve *tpnt, DL_LOADADDR_TYPE load_addr,
if (!_dl_secure || _dl_strchr(str, '/') == NULL) {
_dl_if_debug_dprint("\tfile='%s'; needed by '%s'\n", str, _dl_progname);
- tpnt1 = _dl_load_shared_library(_dl_secure, &rpnt, NULL, str, trace_loaded_objects);
+ tpnt1 = _dl_load_shared_library(
+ _dl_secure ? DL_RESOLVE_SECURE : 0,
+ &rpnt, NULL, str, trace_loaded_objects);
if (!tpnt1) {
#ifdef __LDSO_LDD_SUPPORT__
if (trace_loaded_objects)
diff --git a/ldso/libdl/libdl.c b/ldso/libdl/libdl.c
index 68cd579..edf38d2 100644
--- a/ldso/libdl/libdl.c
+++ b/ldso/libdl/libdl.c
@@ -288,7 +288,7 @@ void *dlopen(const char *libname, int flag)
#endif
/* A bit of sanity checking... */
- if (!(flag & (RTLD_LAZY|RTLD_NOW))) {
+ if (!(flag & (RTLD_LAZY|RTLD_NOW|RTLD_NOLOAD))) {
_dl_error_number = LD_BAD_HANDLE;
return NULL;
}
@@ -358,8 +358,9 @@ void *dlopen(const char *libname, int flag)
/* Try to load the specified library */
_dl_if_debug_print("Trying to dlopen '%s', RTLD_GLOBAL:%d RTLD_NOW:%d\n",
(char*)libname, (flag & RTLD_GLOBAL ? 1:0), (now_flag & RTLD_NOW ? 1:0));
- tpnt = _dl_load_shared_library(0, &rpnt, tfrom, (char*)libname, 0);
+ tpnt = _dl_load_shared_library((flag & RTLD_NOLOAD) ? DL_RESOLVE_NOLOAD : 0,
+ &rpnt, tfrom, (char*)libname, 0);
if (tpnt == NULL) {
_dl_unmap_cache();
return NULL;
diff --git a/libc/sysdeps/linux/common/bits/dlfcn.h b/libc/sysdeps/linux/common/bits/dlfcn.h
index 4bfbbff..47b42ad 100644
--- a/libc/sysdeps/linux/common/bits/dlfcn.h
+++ b/libc/sysdeps/linux/common/bits/dlfcn.h
@@ -24,9 +24,9 @@
/* The MODE argument to `dlopen' contains one of the following: */
#define RTLD_LAZY 0x00001 /* Lazy function call binding. */
#define RTLD_NOW 0x00002 /* Immediate function call binding. */
-#if 0 /* uClibc doesnt support these */
-#define RTLD_BINDING_MASK 0x3 /* Mask of binding time value. */
+#define RTLD_BINDING_MASK 0x3 /* Mask of binding time value. */
#define RTLD_NOLOAD 0x00004 /* Do not load the object. */
+#if 0 /* uClibc doesnt support these */
#define RTLD_DEEPBIND 0x00008 /* Use deep binding. */
#endif
--
1.7.1
More information about the uClibc
mailing list