[HACK] Adding e4crypt support

This is a dirty hack requiring a lot of clean up.
Needed to allow other parts to make progress.

Add e4crypt functions to libext4_utils
Add e4crypt command line tool

Change-Id: Iac5ae75e7f39cccc87701faf1f590e44f5209c0e

1 files changed, 146 insertions, 0 deletions

diff --git a/ext4_utils/e4crypt_static.c b/ext4_utils/e4crypt_static.c
new file mode 100644
index 00000000..187a014f
--- /dev/null
+++ b/ext4_utils/e4crypt_static.c
@@ -0,0 +1,146 @@
+/*
+ * Copyright (c) 2015 Google, Inc.
+ */
+
+#include <dirent.h>
+#include <errno.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <sys/xattr.h>
+#include <sys/syscall.h>
+#include <sys/stat.h>
+
+// ext4enc:TODO Use include paths
+#include "../../core/init/log.h"
+
+#include "ext4_crypt.h"
+
+/* keyring keyctl commands */
+#define KEYCTL_SETPERM        5 /* set permissions for a key in a keyring */
+#define KEYCTL_UNLINK         9 /* unlink a key from a keyring */
+#define KEYCTL_SEARCH        10 /* search for a key in a keyring */
+
+#define XATTR_NAME_ENCRYPTION_POLICY "encryption.policy"
+#define EXT4_KEYREF_DELIMITER ((char)'.')
+
+/* Validate that all path items are available and accessible. */
+static int is_path_valid(const char *path)
+{
+    if (access(path, W_OK)) {
+        ERROR("Can't access %s: %s\n",strerror(errno), path);
+        return 0;
+    }
+
+    return 1;
+}
+
+/* Checks whether the policy provided is valid */
+static int is_keyref_valid(const char *keyref)
+{
+    char *period = 0;
+    size_t key_location_len = 0;
+
+    /* Key ref must have a key and location delimiter character. */
+    period = strchr(keyref, EXT4_KEYREF_DELIMITER);
+    if (!period) {
+        return 0;
+    }
+
+    /* period must be >= keyref. */
+    key_location_len = period - keyref;
+
+    if (strncmp(keyref, "@t", key_location_len) == 0 ||
+        strncmp(keyref, "@p", key_location_len) == 0 ||
+        strncmp(keyref, "@s", key_location_len) == 0 ||
+        strncmp(keyref, "@u", key_location_len) == 0 ||
+        strncmp(keyref, "@g", key_location_len) == 0 ||
+        strncmp(keyref, "@us", key_location_len) == 0)
+        return 1;
+
+    return 0;
+}
+
+static int is_dir_empty(const char *dirname)
+{
+    int n = 0;
+    struct dirent *d;
+    DIR *dir;
+
+    dir = opendir(dirname);
+    while ((d = readdir(dir)) != NULL) {
+        if (strcmp(d->d_name, "lost+found") == 0) {
+            // Skip lost+found directory
+        } else if (++n > 2) {
+            break;
+        }
+    }
+    closedir(dir);
+    return n <= 2;
+}
+
+int do_policy_set(const char *directory, const char *policy)
+{
+    struct stat st;
+    ssize_t ret;
+
+    if (!is_keyref_valid(policy)) {
+        ERROR("Policy has invalid format.\n");
+        return -EINVAL;
+    }
+
+    if (!is_path_valid(directory)) {
+        return -EINVAL;
+    }
+
+    stat(directory, &st);
+    if (!S_ISDIR(st.st_mode)) {
+        ERROR("Can only set policy on a directory (%s)\n", directory);
+        return -EINVAL;
+    }
+
+    if (!is_dir_empty(directory)) {
+        ERROR("Can only set policy on an empty directory (%s)\n", directory);
+        return -EINVAL;
+    }
+
+    ret = lsetxattr(directory, XATTR_NAME_ENCRYPTION_POLICY, policy,
+                    strlen(policy), 0);
+
+    if (ret) {
+        ERROR("Failed to set encryption policy for %s: %s\n",
+               directory, strerror(errno));
+        return -EINVAL;
+    }
+
+    INFO("Encryption policy for %s is set to %s\n", directory, policy);
+    return 0;
+}
+
+static long keyctl(int cmd, ...)
+{
+    va_list va;
+    unsigned long arg2, arg3, arg4, arg5;
+
+    va_start(va, cmd);
+    arg2 = va_arg(va, unsigned long);
+    arg3 = va_arg(va, unsigned long);
+    arg4 = va_arg(va, unsigned long);
+    arg5 = va_arg(va, unsigned long);
+    va_end(va);
+    return syscall(__NR_keyctl, cmd, arg2, arg3, arg4, arg5);
+}
+
+key_serial_t add_key(const char *type,
+                     const char *description,
+                     const void *payload,
+                     size_t plen,
+                     key_serial_t ringid)
+{
+    return syscall(__NR_add_key, type, description, payload, plen, ringid);
+}
+
+long keyctl_setperm(key_serial_t id, int permissions)
+{
+    return keyctl(KEYCTL_SETPERM, id, permissions);
+}