* Copyright (c) 2015 Google, Inc.
*/
-#define TAG "ext4_utils"
-
-#include "ext4_crypt_init_extensions.h"
+#include "ext4_crypt.h"
#include <dirent.h>
#include <errno.h>
#include <sys/stat.h>
#include <sys/types.h>
-#include <cutils/klog.h>
+#include <android-base/logging.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;
#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_SET_ENCRYPTION_POLICY _IOR('f', 19, struct ext4_encryption_policy)
+#define EXT4_IOC_GET_ENCRYPTION_POLICY _IOW('f', 21, struct ext4_encryption_policy)
-/* Validate that all path items are available and accessible. */
-static int is_path_valid(const char *path)
-{
- if (access(path, W_OK)) {
- KLOG_ERROR(TAG, "Can't access %s: %s\n",strerror(errno), path);
- return 0;
- }
+#define HEX_LOOKUP "0123456789abcdef"
- return 1;
+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 int is_dir_empty(const char *dirname)
return n <= 2;
}
-int do_policy_set(const char *directory, const char *policy, int policy_length)
-{
- struct stat st;
- ssize_t ret;
-
+int e4crypt_policy_set(const char *directory, const char *policy, size_t policy_length) {
if (policy_length != EXT4_KEY_DESCRIPTOR_SIZE) {
- KLOG_ERROR("Policy wrong length\n");
- return -EINVAL;
+ LOG(ERROR) << "Policy wrong length: " << policy_length;
+ return -1;
}
- if (!is_path_valid(directory)) {
- return -EINVAL;
+ if (access(directory, W_OK)) {
+ PLOG(ERROR) << "Failed to access directory " << directory;
+ return -1;
}
- stat(directory, &st);
- if (!S_ISDIR(st.st_mode)) {
- KLOG_ERROR(TAG, "Can only set policy on a directory (%s)\n", directory);
- return -EINVAL;
+ int fd = open(directory, O_DIRECTORY | O_NOFOLLOW | O_CLOEXEC);
+ if (fd == -1) {
+ PLOG(ERROR) << "Failed to open directory " << directory;
+ return -1;
}
if (!is_dir_empty(directory)) {
- KLOG_ERROR(TAG, "Can only set policy on an empty directory (%s)\n",
- directory);
- return -EINVAL;
- }
-
- int fd = open(directory, O_DIRECTORY);
- if (fd == -1) {
- KLOG_ERROR(TAG, "Failed to open directory (%s)\n", directory);
- return -EINVAL;
+ LOG(ERROR) << "Can only set policy on an empty directory " << directory;
+ return -1;
}
ext4_encryption_policy eep;
eep.filenames_encryption_mode = EXT4_ENCRYPTION_MODE_AES_256_CTS;
eep.flags = 0;
memcpy(eep.master_key_descriptor, policy, EXT4_KEY_DESCRIPTOR_SIZE);
- ret = ioctl(fd, EXT4_IOC_SET_ENCRYPTION_POLICY, &eep);
- auto preserve_errno = errno;
- close(fd);
-
- if (ret) {
- KLOG_ERROR(TAG, "Failed to set encryption policy for %s: %s\n",
- directory, strerror(preserve_errno));
- return -EINVAL;
+ if (ioctl(fd, EXT4_IOC_SET_ENCRYPTION_POLICY, &eep)) {
+ PLOG(ERROR) << "Failed to set encryption policy for " << directory;
+ close(fd);
+ return -1;
+ } else {
+ close(fd);
}
- KLOG_INFO(TAG, "Encryption policy for %s is set to %02x%02x%02x%02x\n",
- directory, policy[0], policy[1], policy[2], policy[3]);
+ char policy_hex[EXT4_KEY_DESCRIPTOR_SIZE_HEX];
+ policy_to_hex(policy, policy_hex);
+ LOG(INFO) << "Policy for " << directory << " set to " << policy_hex;
return 0;
}
+
+int 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 -1;
+ }
+
+ if (access(directory, W_OK)) {
+ PLOG(ERROR) << "Failed to access directory " << directory;
+ return -1;
+ }
+
+ int fd = open(directory, O_DIRECTORY | O_NOFOLLOW | O_CLOEXEC);
+ if (fd == -1) {
+ PLOG(ERROR) << "Failed to open directory " << directory;
+ return -1;
+ }
+
+ ext4_encryption_policy eep;
+ memset(&eep, 0, sizeof(ext4_encryption_policy));
+
+ if (ioctl(fd, EXT4_IOC_GET_ENCRYPTION_POLICY, &eep)) {
+ PLOG(WARNING) << "Failed to get encryption policy for " << directory;
+ close(fd);
+ return -1;
+ } else {
+ 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)) {
+ memcpy(policy, eep.master_key_descriptor, EXT4_KEY_DESCRIPTOR_SIZE);
+ return 0;
+ }
+
+ LOG(ERROR) << "Failed to find matching encryption policy for " << directory;
+ return -1;
+}
+
+int e4crypt_policy_ensure(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 -1;
+ }
+
+ char existing_policy[EXT4_KEY_DESCRIPTOR_SIZE];
+ if (e4crypt_policy_get(directory, existing_policy, EXT4_KEY_DESCRIPTOR_SIZE) == 0) {
+ char policy_hex[EXT4_KEY_DESCRIPTOR_SIZE_HEX];
+ char existing_policy_hex[EXT4_KEY_DESCRIPTOR_SIZE_HEX];
+
+ policy_to_hex(policy, policy_hex);
+ policy_to_hex(existing_policy, existing_policy_hex);
+
+ if (memcmp(policy, existing_policy, EXT4_KEY_DESCRIPTOR_SIZE) == 0) {
+ LOG(INFO) << "Found policy " << existing_policy_hex << " at " << directory
+ << " which matches expected value";
+ return 0;
+ } else {
+ LOG(ERROR) << "Found policy " << existing_policy_hex << " at " << directory
+ << " which doesn't match expected value " << policy_hex;
+ return -1;
+ }
+ }
+
+ return e4crypt_policy_set(directory, policy, policy_length);
+}
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