Revert "Add fileencrypted=software/ice to fstab options"

This reverts commit e8299d81a18d16b006019f37ec9d84921d5ff845.

Bug: 28905864
Change-Id: I077f1ce7337c7ff42be67fb7acbb80ce5ee9b9ba

4 files changed, 191 insertions, 16 deletions

diff --git a/ext4_utils/Android.mk b/ext4_utils/Android.mk
index e5431dd8..a8362b22 100644
--- a/ext4_utils/Android.mk
+++ b/ext4_utils/Android.mk
@@ -87,7 +87,6 @@ include $(CLEAR_VARS)
 LOCAL_SRC_FILES := $(libext4_utils_src_files) \
     ext4_crypt_init_extensions.cpp
 LOCAL_MODULE := libext4_utils_static
-LOCAL_C_INCLUDES += system/core/init
 # Various instances of dereferencing a type-punned pointer in extent.c
 LOCAL_CFLAGS += -fno-strict-aliasing
 LOCAL_STATIC_LIBRARIES := \
diff --git a/ext4_utils/ext4_crypt.cpp b/ext4_utils/ext4_crypt.cpp
index 72ce104d..be77b791 100644
--- a/ext4_utils/ext4_crypt.cpp
+++ b/ext4_utils/ext4_crypt.cpp
@@ -16,11 +16,182 @@
 
 #include "ext4_crypt.h"
 
+#include <dirent.h>
+#include <errno.h>
 #include <string.h>
+#include <unistd.h>
+
+#include <fcntl.h>
+#include <asm/ioctl.h>
+#include <sys/syscall.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include <android-base/logging.h>
 #include <cutils/properties.h>
 
+#define XATTR_NAME_ENCRYPTION_POLICY "encryption.policy"
+#define EXT4_KEYREF_DELIMITER ((char)'.')
+
+// ext4enc:TODO Include structure from somewhere sensible
+// MUST be in sync with ext4_crypto.c in kernel
+#define EXT4_KEY_DESCRIPTOR_SIZE 8
+#define EXT4_KEY_DESCRIPTOR_SIZE_HEX 17
+
+struct ext4_encryption_policy {
+    char version;
+    char contents_encryption_mode;
+    char filenames_encryption_mode;
+    char flags;
+    char master_key_descriptor[EXT4_KEY_DESCRIPTOR_SIZE];
+} __attribute__((__packed__));
+
+#define EXT4_ENCRYPTION_MODE_AES_256_XTS    1
+#define EXT4_ENCRYPTION_MODE_AES_256_CTS    4
+
+// ext4enc:TODO Get value from somewhere sensible
+#define EXT4_IOC_SET_ENCRYPTION_POLICY _IOR('f', 19, struct ext4_encryption_policy)
+#define EXT4_IOC_GET_ENCRYPTION_POLICY _IOW('f', 21, struct ext4_encryption_policy)
+
+#define HEX_LOOKUP "0123456789abcdef"
+
 bool e4crypt_is_native() {
     char value[PROPERTY_VALUE_MAX];
     property_get("ro.crypto.type", value, "none");
     return !strcmp(value, "file");
 }
+
+static void policy_to_hex(const char* policy, char* hex) {
+    for (size_t i = 0, j = 0; i < EXT4_KEY_DESCRIPTOR_SIZE; i++) {
+        hex[j++] = HEX_LOOKUP[(policy[i] & 0xF0) >> 4];
+        hex[j++] = HEX_LOOKUP[policy[i] & 0x0F];
+    }
+    hex[EXT4_KEY_DESCRIPTOR_SIZE_HEX - 1] = '\0';
+}
+
+static bool is_dir_empty(const char *dirname, bool *is_empty)
+{
+    int n = 0;
+    auto dirp = std::unique_ptr<DIR, int (*)(DIR*)>(opendir(dirname), closedir);
+    if (!dirp) {
+        PLOG(ERROR) << "Unable to read directory: " << dirname;
+        return false;
+    }
+    for (;;) {
+        errno = 0;
+        auto entry = readdir(dirp.get());
+        if (!entry) {
+            if (errno) {
+                PLOG(ERROR) << "Unable to read directory: " << dirname;
+                return false;
+            }
+            break;
+        }
+        if (strcmp(entry->d_name, "lost+found") != 0) { // Skip lost+found
+            ++n;
+            if (n > 2) {
+                *is_empty = false;
+                return true;
+            }
+        }
+    }
+    *is_empty = true;
+    return true;
+}
+
+static bool e4crypt_policy_set(const char *directory, const char *policy, size_t policy_length) {
+    if (policy_length != EXT4_KEY_DESCRIPTOR_SIZE) {
+        LOG(ERROR) << "Policy wrong length: " << policy_length;
+        return false;
+    }
+    int fd = open(directory, O_DIRECTORY | O_NOFOLLOW | O_CLOEXEC);
+    if (fd == -1) {
+        PLOG(ERROR) << "Failed to open directory " << directory;
+        return false;
+    }
+
+    ext4_encryption_policy eep;
+    eep.version = 0;
+    eep.contents_encryption_mode = EXT4_ENCRYPTION_MODE_AES_256_XTS;
+    eep.filenames_encryption_mode = EXT4_ENCRYPTION_MODE_AES_256_CTS;
+    eep.flags = 0;
+    memcpy(eep.master_key_descriptor, policy, EXT4_KEY_DESCRIPTOR_SIZE);
+    if (ioctl(fd, EXT4_IOC_SET_ENCRYPTION_POLICY, &eep)) {
+        PLOG(ERROR) << "Failed to set encryption policy for " << directory;
+        close(fd);
+        return false;
+    }
+    close(fd);
+
+    char policy_hex[EXT4_KEY_DESCRIPTOR_SIZE_HEX];
+    policy_to_hex(policy, policy_hex);
+    LOG(INFO) << "Policy for " << directory << " set to " << policy_hex;
+    return true;
+}
+
+static bool e4crypt_policy_get(const char *directory, char *policy, size_t policy_length) {
+    if (policy_length != EXT4_KEY_DESCRIPTOR_SIZE) {
+        LOG(ERROR) << "Policy wrong length: " << policy_length;
+        return false;
+    }
+
+    int fd = open(directory, O_DIRECTORY | O_NOFOLLOW | O_CLOEXEC);
+    if (fd == -1) {
+        PLOG(ERROR) << "Failed to open directory " << directory;
+        return false;
+    }
+
+    ext4_encryption_policy eep;
+    memset(&eep, 0, sizeof(ext4_encryption_policy));
+    if (ioctl(fd, EXT4_IOC_GET_ENCRYPTION_POLICY, &eep) != 0) {
+        PLOG(ERROR) << "Failed to get encryption policy for " << directory;
+        close(fd);
+        return -1;
+    }
+    close(fd);
+
+    if ((eep.version != 0)
+            || (eep.contents_encryption_mode != EXT4_ENCRYPTION_MODE_AES_256_XTS)
+            || (eep.filenames_encryption_mode != EXT4_ENCRYPTION_MODE_AES_256_CTS)
+            || (eep.flags != 0)) {
+        LOG(ERROR) << "Failed to find matching encryption policy for " << directory;
+        return false;
+    }
+    memcpy(policy, eep.master_key_descriptor, EXT4_KEY_DESCRIPTOR_SIZE);
+
+    return true;
+}
+
+static bool e4crypt_policy_check(const char *directory, const char *policy, size_t policy_length) {
+    if (policy_length != EXT4_KEY_DESCRIPTOR_SIZE) {
+        LOG(ERROR) << "Policy wrong length: " << policy_length;
+        return false;
+    }
+    char existing_policy[EXT4_KEY_DESCRIPTOR_SIZE];
+    if (!e4crypt_policy_get(directory, existing_policy, EXT4_KEY_DESCRIPTOR_SIZE)) return false;
+    char existing_policy_hex[EXT4_KEY_DESCRIPTOR_SIZE_HEX];
+
+    policy_to_hex(existing_policy, existing_policy_hex);
+
+    if (memcmp(policy, existing_policy, EXT4_KEY_DESCRIPTOR_SIZE) != 0) {
+        char policy_hex[EXT4_KEY_DESCRIPTOR_SIZE_HEX];
+        policy_to_hex(policy, policy_hex);
+        LOG(ERROR) << "Found policy " << existing_policy_hex << " at " << directory
+                   << " which doesn't match expected value " << policy_hex;
+        return false;
+    }
+    LOG(INFO) << "Found policy " << existing_policy_hex << " at " << directory
+              << " which matches expected value";
+    return true;
+}
+
+int e4crypt_policy_ensure(const char *directory, const char *policy, size_t policy_length) {
+    bool is_empty;
+    if (!is_dir_empty(directory, &is_empty)) return -1;
+    if (is_empty) {
+        if (!e4crypt_policy_set(directory, policy, policy_length)) return -1;
+    } else {
+        if (!e4crypt_policy_check(directory, policy, policy_length)) return -1;
+    }
+    return 0;
+}
diff --git a/ext4_utils/ext4_crypt.h b/ext4_utils/ext4_crypt.h
index 8a83da19..ddc09a71 100644
--- a/ext4_utils/ext4_crypt.h
+++ b/ext4_utils/ext4_crypt.h
@@ -20,9 +20,11 @@
 
 __BEGIN_DECLS
 
+bool e4crypt_is_native();
+
+int e4crypt_policy_ensure(const char *directory, const char* policy, size_t policy_length);
+
 static const char* e4crypt_unencrypted_folder = "/unencrypted";
 static const char* e4crypt_key_ref = "/unencrypted/ref";
 
-bool e4crypt_is_native();
-
 __END_DECLS
diff --git a/ext4_utils/ext4_crypt_init_extensions.cpp b/ext4_utils/ext4_crypt_init_extensions.cpp
index 0298b116..c6baea74 100644
--- a/ext4_utils/ext4_crypt_init_extensions.cpp
+++ b/ext4_utils/ext4_crypt_init_extensions.cpp
@@ -24,11 +24,18 @@
 #include <string>
 #include <vector>
 
+#include <dirent.h>
+#include <errno.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
 #include <android-base/file.h>
 
 #include <cutils/klog.h>
+#include <cutils/properties.h>
+#include <cutils/sockets.h>
 #include <logwrap/logwrap.h>
-#include <util.h>
 
 #include "key_control.h"
 
@@ -110,6 +117,9 @@ int e4crypt_set_directory_policy(const char* dir)
         return 0;
     }
 
+    // Special case various directories that must not be encrypted,
+    // often because their subdirectories must be encrypted.
+    // This isn't a nice way to do this, see b/26641735
     std::vector<std::string> directories_to_exclude = {
         "lost+found",
         "system_ce", "system_de",
@@ -131,19 +141,12 @@ int e4crypt_set_directory_policy(const char* dir)
         KLOG_ERROR(TAG, "Unable to read system policy to set on %s\n", dir);
         return -1;
     }
-
-    std::string hex_policy = bytes_to_hex((const uint8_t*)policy.c_str(),
-                                          policy.length());
-
-    const char* argv[] = { "/system/bin/vdc", "--wait", "cryptfs",
-                           "ensure_policy", dir, hex_policy.c_str()};
-
     KLOG_INFO(TAG, "Setting policy on %s\n", dir);
-    int rc = android_fork_execvp(6, (char**) argv, NULL, false, true);
-    if (rc) {
-        KLOG_ERROR(TAG, "Setting %s policy on %s failed!\n",
-                   hex_policy.c_str(), dir);
-        return rc;
+    int result = e4crypt_policy_ensure(dir, policy.c_str(), policy.size());
+    if (result) {
+        KLOG_ERROR(TAG, "Setting %02x%02x%02x%02x policy on %s failed!\n",
+                   policy[0], policy[1], policy[2], policy[3], dir);
+        return -1;
     }
 
     return 0;