linker: Allow link namespaces without name filters

This commit allows users to create a link without soname filters between
two linker namespaces.

The motivation is to establish one-way shared library isolation.  For
example, assume that there are two linker namespaces `default` and
`vndk`.  We would like to limit the shared libraries that can be used by
the `default` namespace.  In the meanwhile, we would like to allow the
`vndk` namespace to use shared libs from the `default` namespace if the
soname cannot be find in the search path or loaded sonames of the `vndk`
namespace.

          shared_libs  = %VNDK_CORE_LIBRARIES%
          shared_libs += %VNDK_SAMEPROCESS_LIBRARIES%
    vndk <-------------------------------------------- default
       \_______________________________________________/^
                allow_all_shared_libs = true

android_link_namespaces_all_libs() is added to libdl, but it is
versioned as LIBC_PRIVATE.  android_link_namespaces_all_libs() is only
for unit tests.

Bug: 69824336

Test: adb shell /data/nativetest/linker-unit-tests/linker-unit-tests32
Test: adb shell /data/nativetest64/linker-unit-tests/linker-unit-tests64

Test: adb shell /data/nativetest/bionic-unit-tests/bionic-unit-tests
Test: adb shell /data/nativetest64/bionic-unit-tests/bionic-unit-tests

Test: Update /system/etc/ld.config*.txt and check whether the vndk
linker namespace of the vendor process can access the shared libs from
the default linker namespace.

Change-Id: I2879f0c5f5af60c7e56f8f743ebd2872e552286b

8 files changed, 46 insertions, 0 deletions

diff --git a/libdl/libdl.arm.map b/libdl/libdl.arm.map
index 1fcfc584d..7ed950361 100644
--- a/libdl/libdl.arm.map
+++ b/libdl/libdl.arm.map
@@ -41,6 +41,11 @@ LIBC_OMR1 { # introduced=27
     __cfi_slowpath_diag;
 } LIBC_N;
 
+LIBC_PRIVATE {
+  global:
+    android_link_namespaces_all_libs;
+} LIBC_OMR1;
+
 LIBC_PLATFORM {
   global:
     __cfi_init;
diff --git a/libdl/libdl.arm64.map b/libdl/libdl.arm64.map
index 8d4019ce4..199f2e344 100644
--- a/libdl/libdl.arm64.map
+++ b/libdl/libdl.arm64.map
@@ -40,6 +40,11 @@ LIBC_OMR1 { # introduced=27
     __cfi_slowpath_diag;
 } LIBC_N;
 
+LIBC_PRIVATE {
+  global:
+    android_link_namespaces_all_libs;
+} LIBC_OMR1;
+
 LIBC_PLATFORM {
   global:
     __cfi_init;
diff --git a/libdl/libdl.cpp b/libdl/libdl.cpp
index c8340888e..4c2415f1f 100644
--- a/libdl/libdl.cpp
+++ b/libdl/libdl.cpp
@@ -93,6 +93,11 @@ bool __loader_android_link_namespaces(
                                 const char* shared_libs_sonames);
 
 __attribute__((__weak__, visibility("default")))
+bool __loader_android_link_namespaces_all_libs(
+                                struct android_namespace_t* namespace_from,
+                                struct android_namespace_t* namespace_to);
+
+__attribute__((__weak__, visibility("default")))
 void __loader_android_dlwarning(void* obj, void (*f)(void*, const char*));
 
 __attribute__((__weak__, visibility("default")))
@@ -205,6 +210,12 @@ bool android_link_namespaces(struct android_namespace_t* namespace_from,
 }
 
 __attribute__((__weak__))
+bool android_link_namespaces_all_libs(struct android_namespace_t* namespace_from,
+                                      struct android_namespace_t* namespace_to) {
+  return __loader_android_link_namespaces_all_libs(namespace_from, namespace_to);
+}
+
+__attribute__((__weak__))
 void android_dlwarning(void* obj, void (*f)(void*, const char*)) {
   __loader_android_dlwarning(obj, f);
 }
diff --git a/libdl/libdl.map.txt b/libdl/libdl.map.txt
index 002e9f828..579ffa709 100644
--- a/libdl/libdl.map.txt
+++ b/libdl/libdl.map.txt
@@ -40,6 +40,11 @@ LIBC_OMR1 { # introduced=27
     __cfi_slowpath_diag;
 } LIBC_N;
 
+LIBC_PRIVATE {
+  global:
+    android_link_namespaces_all_libs;
+} LIBC_OMR1;
+
 LIBC_PLATFORM {
   global:
     __cfi_init;
diff --git a/libdl/libdl.mips.map b/libdl/libdl.mips.map
index 8d4019ce4..199f2e344 100644
--- a/libdl/libdl.mips.map
+++ b/libdl/libdl.mips.map
@@ -40,6 +40,11 @@ LIBC_OMR1 { # introduced=27
     __cfi_slowpath_diag;
 } LIBC_N;
 
+LIBC_PRIVATE {
+  global:
+    android_link_namespaces_all_libs;
+} LIBC_OMR1;
+
 LIBC_PLATFORM {
   global:
     __cfi_init;
diff --git a/libdl/libdl.mips64.map b/libdl/libdl.mips64.map
index 8d4019ce4..199f2e344 100644
--- a/libdl/libdl.mips64.map
+++ b/libdl/libdl.mips64.map
@@ -40,6 +40,11 @@ LIBC_OMR1 { # introduced=27
     __cfi_slowpath_diag;
 } LIBC_N;
 
+LIBC_PRIVATE {
+  global:
+    android_link_namespaces_all_libs;
+} LIBC_OMR1;
+
 LIBC_PLATFORM {
   global:
     __cfi_init;
diff --git a/libdl/libdl.x86.map b/libdl/libdl.x86.map
index 8d4019ce4..199f2e344 100644
--- a/libdl/libdl.x86.map
+++ b/libdl/libdl.x86.map
@@ -40,6 +40,11 @@ LIBC_OMR1 { # introduced=27
     __cfi_slowpath_diag;
 } LIBC_N;
 
+LIBC_PRIVATE {
+  global:
+    android_link_namespaces_all_libs;
+} LIBC_OMR1;
+
 LIBC_PLATFORM {
   global:
     __cfi_init;
diff --git a/libdl/libdl.x86_64.map b/libdl/libdl.x86_64.map
index 8d4019ce4..199f2e344 100644
--- a/libdl/libdl.x86_64.map
+++ b/libdl/libdl.x86_64.map
@@ -40,6 +40,11 @@ LIBC_OMR1 { # introduced=27
     __cfi_slowpath_diag;
 } LIBC_N;
 
+LIBC_PRIVATE {
+  global:
+    android_link_namespaces_all_libs;
+} LIBC_OMR1;
+
 LIBC_PLATFORM {
   global:
     __cfi_init;