adb: Support 'adb enable/disable-verity' when using AVB.

Link with libavb_user and use this to enable/disable dm-verity if AVB
is in use.

Bug: 34124301
Test: Manually tested.
Change-Id: Ic03651312b955081cb3c126f6dafc46d6eeec0da

adb/Android.mk

@@ -363,6 +363,7 @@ LOCAL_SANITIZE := $(adb_target_sanitize)
 LOCAL_STRIP_MODULE := keep_symbols
 LOCAL_STATIC_LIBRARIES := \
     libadbd \
+    libavb_user \
     libbase \
     libbootloader_message \
     libfs_mgr \

adb/set_verity_enable_state_service.cpp

@@ -20,6 +20,7 @@
 
 #include <fcntl.h>
 #include <inttypes.h>
+#include <libavb_user/libavb_user.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include <sys/stat.h>
@@ -45,13 +46,12 @@ static const bool kAllowDisableVerity = false;
 #endif
 
 /* Turn verity on/off */
-static int set_verity_enabled_state(int fd, const char *block_device,
-                                    const char* mount_point, bool enable)
-{
+static bool set_verity_enabled_state(int fd, const char* block_device, const char* mount_point,
+                                     bool enable) {
     if (!make_block_device_writable(block_device)) {
         WriteFdFmt(fd, "Could not make block device %s writable (%s).\n",
                    block_device, strerror(errno));
-        return -1;
+        return false;
     }
 
     fec::io fh(block_device, O_RDWR);
@@ -59,39 +59,84 @@ static int set_verity_enabled_state(int fd, const char *block_device,
     if (!fh) {
         WriteFdFmt(fd, "Could not open block device %s (%s).\n", block_device, strerror(errno));
         WriteFdFmt(fd, "Maybe run adb root?\n");
-        return -1;
+        return false;
     }
 
     fec_verity_metadata metadata;
 
     if (!fh.get_verity_metadata(metadata)) {
         WriteFdFmt(fd, "Couldn't find verity metadata!\n");
-        return -1;
+        return false;
     }
 
     if (!enable && metadata.disabled) {
         WriteFdFmt(fd, "Verity already disabled on %s\n", mount_point);
-        return -1;
+        return false;
     }
 
     if (enable && !metadata.disabled) {
         WriteFdFmt(fd, "Verity already enabled on %s\n", mount_point);
-        return -1;
+        return false;
     }
 
     if (!fh.set_verity_status(enable)) {
         WriteFdFmt(fd, "Could not set verity %s flag on device %s with error %s\n",
                    enable ? "enabled" : "disabled",
                    block_device, strerror(errno));
-        return -1;
+        return false;
     }
 
     WriteFdFmt(fd, "Verity %s on %s\n", enable ? "enabled" : "disabled", mount_point);
-    return 0;
+    return true;
+}
+
+/* Helper function to get A/B suffix, if any. If the device isn't
+ * using A/B the empty string is returned. Otherwise either "_a",
+ * "_b", ... is returned.
+ *
+ * Note that since sometime in O androidboot.slot_suffix is deprecated
+ * and androidboot.slot should be used instead. Since bootloaders may
+ * be out of sync with the OS, we check both and for extra safety
+ * prepend a leading underscore if there isn't one already.
+ */
+static std::string get_ab_suffix() {
+    std::string ab_suffix = android::base::GetProperty("ro.boot.slot_suffix", "");
+    if (ab_suffix == "") {
+        ab_suffix = android::base::GetProperty("ro.boot.slot", "");
+    }
+    if (ab_suffix.size() > 0 && ab_suffix[0] != '_') {
+        ab_suffix = std::string("_") + ab_suffix;
+    }
+    return ab_suffix;
+}
+
+/* Use AVB to turn verity on/off */
+static bool set_avb_verity_enabled_state(int fd, AvbOps* ops, bool enable_verity) {
+    std::string ab_suffix = get_ab_suffix();
+
+    bool verity_enabled;
+    if (!avb_user_verity_get(ops, ab_suffix.c_str(), &verity_enabled)) {
+        WriteFdFmt(fd, "Error getting verity state\n");
+        return false;
+    }
+
+    if ((verity_enabled && enable_verity) || (!verity_enabled && !enable_verity)) {
+        WriteFdFmt(fd, "verity is already %s\n", verity_enabled ? "enabled" : "disabled");
+        return false;
+    }
+
+    if (!avb_user_verity_set(ops, ab_suffix.c_str(), enable_verity)) {
+        WriteFdFmt(fd, "Error setting verity\n");
+        return false;
+    }
+
+    WriteFdFmt(fd, "Successfully %s verity\n", enable_verity ? "enabled" : "disabled");
+    return true;
 }
 
 void set_verity_enabled_state_service(int fd, void* cookie) {
     unique_fd closer(fd);
+    bool any_changed = false;
 
     bool enable = (cookie != NULL);
     if (!kAllowDisableVerity) {
@@ -108,6 +153,23 @@ void set_verity_enabled_state_service(int fd, void* cookie) {
         return;
     }
 
+    // Figure out if we're using VB1.0 or VB2.0 (aka AVB).
+    std::string vbmeta_hash = android::base::GetProperty("ro.boot.vbmeta.digest", "");
+    if (vbmeta_hash != "") {
+        // Yep, the system is using AVB (by contract, androidboot.vbmeta.hash is
+        // set by the bootloader when using AVB).
+        AvbOps* ops = avb_ops_user_new();
+        if (ops == nullptr) {
+            WriteFdFmt(fd, "Error getting AVB ops\n");
+            return;
+        }
+        if (set_avb_verity_enabled_state(fd, ops, enable)) {
+            any_changed = true;
+        }
+        avb_ops_user_free(ops);
+    } else {
+        // Not using AVB - assume VB1.0.
+
         // read all fstab entries at once from all sources
         fstab = fs_mgr_read_fstab_default();
         if (!fstab) {
@@ -116,16 +178,15 @@ void set_verity_enabled_state_service(int fd, void* cookie) {
         }
 
         // Loop through entries looking for ones that vold manages.
-    bool any_changed = false;
         for (int i = 0; i < fstab->num_entries; i++) {
             if (fs_mgr_is_verified(&fstab->recs[i])) {
-            if (!set_verity_enabled_state(fd, fstab->recs[i].blk_device,
-                                          fstab->recs[i].mount_point,
-                                          enable)) {
+                if (set_verity_enabled_state(fd, fstab->recs[i].blk_device,
+                                             fstab->recs[i].mount_point, enable)) {
                     any_changed = true;
                 }
             }
         }
+    }
 
     if (any_changed) {
         WriteFdFmt(fd, "Now reboot your device for settings to take effect\n");