Add support for protected local symbol lookup.
Bug: http://code.google.com/p/android/issues/detail?id=66048
Change-Id: Ib334223df27adad9477fb241ab099c5e26df4a7d
diff --git a/linker/linker.cpp b/linker/linker.cpp
index 4588948..442f7ce 100644
--- a/linker/linker.cpp
+++ b/linker/linker.cpp
@@ -125,6 +125,11 @@
kRelocMax
};
+enum class SymbolLookupScope {
+ kAllowLocal,
+ kExcludeLocal,
+};
+
#if STATS
struct linker_stats_t {
int count[kRelocMax];
@@ -431,7 +436,7 @@
return rv;
}
-static ElfW(Sym)* soinfo_elf_lookup(soinfo* si, unsigned hash, const char* name) {
+static ElfW(Sym)* soinfo_elf_lookup(soinfo* si, unsigned hash, const char* name, const SymbolLookupScope& lookup_scope) {
ElfW(Sym)* symtab = si->symtab;
const char* strtab = si->strtab;
@@ -442,18 +447,30 @@
ElfW(Sym)* s = symtab + n;
if (strcmp(strtab + s->st_name, name)) continue;
- /* only concern ourselves with global and weak symbol definitions */
switch (ELF_ST_BIND(s->st_info)) {
case STB_GLOBAL:
case STB_WEAK:
if (s->st_shndx == SHN_UNDEF) {
- continue;
- }
+ continue;
+ }
- TRACE_TYPE(LOOKUP, "FOUND %s in %s (%p) %zd",
+ TRACE_TYPE(LOOKUP, "FOUND %s in %s (%p) %zd",
name, si->name, reinterpret_cast<void*>(s->st_value),
static_cast<size_t>(s->st_size));
- return s;
+ return s;
+ case STB_LOCAL:
+ if (lookup_scope != SymbolLookupScope::kAllowLocal) {
+ continue;
+ }
+ TRACE_TYPE(LOOKUP, "FOUND LOCAL %s in %s (%p) %zd",
+ name, si->name, reinterpret_cast<void*>(s->st_value),
+ static_cast<size_t>(s->st_size));
+ return s;
+ default:
+ const char* msg = "FATAL: Unexpected ST_BIND\n";
+ __libc_format_log(ANDROID_LOG_FATAL, "linker", "%s", msg);
+ write(2, msg, strlen(msg));
+ abort();
}
}
@@ -484,7 +501,7 @@
*/
if (si == somain) {
- s = soinfo_elf_lookup(si, elf_hash, name);
+ s = soinfo_elf_lookup(si, elf_hash, name, SymbolLookupScope::kAllowLocal);
if (s != NULL) {
*lsi = si;
goto done;
@@ -501,7 +518,7 @@
if (!si->has_DT_SYMBOLIC) {
DEBUG("%s: looking up %s in executable %s",
si->name, name, somain->name);
- s = soinfo_elf_lookup(somain, elf_hash, name);
+ s = soinfo_elf_lookup(somain, elf_hash, name, SymbolLookupScope::kExcludeLocal);
if (s != NULL) {
*lsi = somain;
goto done;
@@ -518,7 +535,7 @@
* and some the first non-weak definition. This is system dependent.
* Here we return the first definition found for simplicity. */
- s = soinfo_elf_lookup(si, elf_hash, name);
+ s = soinfo_elf_lookup(si, elf_hash, name, SymbolLookupScope::kAllowLocal);
if (s != NULL) {
*lsi = si;
goto done;
@@ -532,7 +549,7 @@
if (si->has_DT_SYMBOLIC) {
DEBUG("%s: looking up %s in executable %s after local scope",
si->name, name, somain->name);
- s = soinfo_elf_lookup(somain, elf_hash, name);
+ s = soinfo_elf_lookup(somain, elf_hash, name, SymbolLookupScope::kExcludeLocal);
if (s != NULL) {
*lsi = somain;
goto done;
@@ -543,7 +560,7 @@
/* Next, look for it in the preloads list */
for (int i = 0; g_ld_preloads[i] != NULL; i++) {
- s = soinfo_elf_lookup(g_ld_preloads[i], elf_hash, name);
+ s = soinfo_elf_lookup(g_ld_preloads[i], elf_hash, name, SymbolLookupScope::kExcludeLocal);
if (s != NULL) {
*lsi = g_ld_preloads[i];
goto done;
@@ -553,7 +570,7 @@
for (int i = 0; needed[i] != NULL; i++) {
DEBUG("%s: looking up %s in %s",
si->name, name, needed[i]->name);
- s = soinfo_elf_lookup(needed[i], elf_hash, name);
+ s = soinfo_elf_lookup(needed[i], elf_hash, name, SymbolLookupScope::kExcludeLocal);
if (s != NULL) {
*lsi = needed[i];
goto done;
@@ -582,8 +599,9 @@
Binary Interface) where in Chapter 5 it discuss resolving "Shared
Object Dependencies" in breadth first search order.
*/
-ElfW(Sym)* dlsym_handle_lookup(soinfo* si, const char* name) {
- return soinfo_elf_lookup(si, elfhash(name), name);
+ElfW(Sym)* dlsym_handle_lookup(soinfo* si, const char* name, soinfo* caller) {
+ return soinfo_elf_lookup(si, elfhash(name), name,
+ caller == si ? SymbolLookupScope::kAllowLocal : SymbolLookupScope::kExcludeLocal);
}
/* This is used by dlsym(3) to performs a global symbol lookup. If the
@@ -591,7 +609,7 @@
beginning of the global solist. Otherwise the search starts at the
specified soinfo (for RTLD_NEXT).
*/
-ElfW(Sym)* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start) {
+ElfW(Sym)* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start, soinfo* caller) {
unsigned elf_hash = elfhash(name);
if (start == NULL) {
@@ -600,7 +618,8 @@
ElfW(Sym)* s = NULL;
for (soinfo* si = start; (s == NULL) && (si != NULL); si = si->next) {
- s = soinfo_elf_lookup(si, elf_hash, name);
+ s = soinfo_elf_lookup(si, elf_hash, name,
+ caller == si ? SymbolLookupScope::kAllowLocal : SymbolLookupScope::kExcludeLocal);
if (s != NULL) {
*found = si;
break;