Have `otapreopt_chroot` bind-mount Bionic artifacts from the Runtime APEX.

Have `otapreopt_chroot` bind-mount Bionic artifacts (`linker(64)`,
`libc.so`, `libm.so`, `libdl.so`) from the Runtime APEX
(`/postinstall/apex/com.android.runtime`) into `/postinstall/bionic/`,
much the same way `init` sets up Bionic bind-mounts in the default
mount namespace.

Test: m otapreopt_chroot
Test: A/B OTA update test (asit/dexoptota/self_full).
Bug: 113373927
Bug: 120266448
Change-Id: Ie254a94ae35e62f88375bc89380456f15796566a

1 files changed, 71 insertions, 0 deletions

diff --git a/cmds/installd/otapreopt_chroot.cpp b/cmds/installd/otapreopt_chroot.cpp
index 1c996632bf..609ddaf9d7 100644
--- a/cmds/installd/otapreopt_chroot.cpp
+++ b/cmds/installd/otapreopt_chroot.cpp
@@ -41,6 +41,23 @@ using android::base::StringPrintf;
 namespace android {
 namespace installd {
 
+// Configuration for bind-mounted Bionic artifacts.
+
+static constexpr const char* kLinkerMountPoint = "/bionic/bin/linker";
+static constexpr const char* kRuntimeLinkerPath = "/apex/com.android.runtime/bin/linker";
+
+static constexpr const char* kBionicLibsMountPointDir = "/bionic/lib/";
+static constexpr const char* kRuntimeBionicLibsDir = "/apex/com.android.runtime/lib/bionic/";
+
+static constexpr const char* kLinkerMountPoint64 = "/bionic/bin/linker64";
+static constexpr const char* kRuntimeLinkerPath64 = "/apex/com.android.runtime/bin/linker64";
+
+static constexpr const char* kBionicLibsMountPointDir64 = "/bionic/lib64/";
+static constexpr const char* kRuntimeBionicLibsDir64 = "/apex/com.android.runtime/lib64/bionic/";
+
+static const std::vector<std::string> kBionicLibFileNames = {"libc.so", "libm.so", "libdl.so"};
+
+
 static void CloseDescriptor(int fd) {
     if (fd >= 0) {
         int result = close(fd);
@@ -79,6 +96,43 @@ static void DeactivateApexPackages(const std::vector<apex::ApexFile>& active_pac
     }
 }
 
+// Copied from system/core/init/mount_namespace.cpp.
+static bool BindMount(const std::string& source, const std::string& mount_point,
+                      bool recursive = false) {
+    unsigned long mountflags = MS_BIND;
+    if (recursive) {
+        mountflags |= MS_REC;
+    }
+    if (mount(source.c_str(), mount_point.c_str(), nullptr, mountflags, nullptr) == -1) {
+        PLOG(ERROR) << "Could not bind-mount " << source << " to " << mount_point;
+        return false;
+    }
+    return true;
+}
+
+// Copied from system/core/init/mount_namespace.cpp and and adjusted (bind
+// mounts are not made private, as the /postinstall is already private (see
+// `android::installd::otapreopt_chroot`).
+static bool BindMountBionic(const std::string& linker_source, const std::string& lib_dir_source,
+                            const std::string& linker_mount_point,
+                            const std::string& lib_mount_dir) {
+    if (access(linker_source.c_str(), F_OK) != 0) {
+        PLOG(INFO) << linker_source << " does not exist. Skipping mounting Bionic there.";
+        return true;
+    }
+    if (!BindMount(linker_source, linker_mount_point)) {
+        return false;
+    }
+    for (const auto& libname : kBionicLibFileNames) {
+        std::string mount_point = lib_mount_dir + libname;
+        std::string source = lib_dir_source + libname;
+        if (!BindMount(source, mount_point)) {
+            return false;
+        }
+    }
+    return true;
+}
+
 // Entry for otapreopt_chroot. Expected parameters are:
 //   [cmd] [status-fd] [target-slot] "dexopt" [dexopt-params]
 // The file descriptor denoted by status-fd will be closed. The rest of the parameters will
@@ -222,6 +276,23 @@ static int otapreopt_chroot(const int argc, char **arg) {
     // the Android Runtime APEX, as it is required by otapreopt to run dex2oat.
     std::vector<apex::ApexFile> active_packages = ActivateApexPackages();
 
+    // Bind-mount Bionic artifacts from the Runtime APEX.
+    // This logic is copied and adapted from system/core/init/mount_namespace.cpp.
+    if (!BindMountBionic(kRuntimeLinkerPath, kRuntimeBionicLibsDir, kLinkerMountPoint,
+                         kBionicLibsMountPointDir)) {
+        LOG(ERROR) << "Failed to mount 32-bit Bionic artifacts from the Runtime APEX.";
+        // Clean up and exit.
+        DeactivateApexPackages(active_packages);
+        exit(215);
+    }
+    if (!BindMountBionic(kRuntimeLinkerPath64, kRuntimeBionicLibsDir64, kLinkerMountPoint64,
+                         kBionicLibsMountPointDir64)) {
+        LOG(ERROR) << "Failed to mount 64-bit Bionic artifacts from the Runtime APEX.";
+        // Clean up and exit.
+        DeactivateApexPackages(active_packages);
+        exit(216);
+    }
+
     // Now go on and run otapreopt.
 
     // Incoming:  cmd + status-fd + target-slot + cmd...      | Incoming | = argc