From 71413f4ee9a2d345da059793e795d798924b2209 Mon Sep 17 00:00:00 2001
From: Ethan Yonker <dees_troy@teamw.in>
Date: Wed, 26 Feb 2014 13:36:08 -0600
Subject: Check crypto footer before offering to decrypt

Verify that we have a valid footer with proper magic before
setting things up for decryption to help prevent user confusion
when dealing with data partitions that fail to mount. Also check
to make sure that the block device for /data is present.

Change-Id: Ie87818fe4505a8bf71df7d3934c114e7328ef3ca
---
 crypto/ics/cryptfs.c | 22 ++++++++++++++++++++++
 crypto/ics/cryptfs.h |  1 +
 crypto/jb/cryptfs.c  | 23 +++++++++++++++++++++--
 crypto/jb/cryptfs.h  |  1 +
 4 files changed, 45 insertions(+), 2 deletions(-)

(limited to 'crypto')

diff --git a/crypto/ics/cryptfs.c b/crypto/ics/cryptfs.c
index 193339ec9..4f3d5d01a 100644
--- a/crypto/ics/cryptfs.c
+++ b/crypto/ics/cryptfs.c
@@ -653,6 +653,28 @@ int cryptfs_crypto_complete(void)
   return -1;
 }
 
+int cryptfs_check_footer(void)
+{
+    int rc = -1;
+    char fs_type[PROPERTY_VALUE_MAX];
+    char real_blkdev[MAXPATHLEN];
+    char fs_options[PROPERTY_VALUE_MAX];
+    unsigned long mnt_flags;
+    struct crypt_mnt_ftr crypt_ftr;
+    /* Allocate enough space for a 256 bit key, but we may use less */
+    unsigned char encrypted_master_key[256];
+    unsigned char salt[SALT_LEN];
+
+    if (get_orig_mount_parms(DATA_MNT_POINT, fs_type, real_blkdev, &mnt_flags, fs_options)) {
+        printf("Error reading original mount parms for mount point %s\n", DATA_MNT_POINT);
+        return rc;
+    }
+
+    rc = get_crypt_ftr_and_key(real_blkdev, &crypt_ftr, encrypted_master_key, salt);
+
+    return rc;
+}
+
 int cryptfs_check_passwd(const char *passwd)
 {
     char pwbuf[256];
diff --git a/crypto/ics/cryptfs.h b/crypto/ics/cryptfs.h
index eee43b3bc..8c8037659 100644
--- a/crypto/ics/cryptfs.h
+++ b/crypto/ics/cryptfs.h
@@ -76,6 +76,7 @@ struct crypt_mnt_ftr {
 #ifdef __cplusplus
 extern "C" {
 #endif
+  int cryptfs_check_footer(void);
   int cryptfs_check_passwd(const char *pw);
 #ifdef __cplusplus
 }
diff --git a/crypto/jb/cryptfs.c b/crypto/jb/cryptfs.c
index 4e5706b64..f9c0d7489 100644
--- a/crypto/jb/cryptfs.c
+++ b/crypto/jb/cryptfs.c
@@ -1354,13 +1354,32 @@ int cryptfs_crypto_complete(void)
 
 #define FSTAB_PREFIX "/fstab."
 
+int cryptfs_check_footer(void)
+{
+    int rc = -1;
+    char fstab_filename[PROPERTY_VALUE_MAX + sizeof(FSTAB_PREFIX)];
+    char propbuf[PROPERTY_VALUE_MAX];
+    struct crypt_mnt_ftr crypt_ftr;
+
+    property_get("ro.hardware", propbuf, "");
+    snprintf(fstab_filename, sizeof(fstab_filename), FSTAB_PREFIX"%s", propbuf);
+
+    fstab = fs_mgr_read_fstab(fstab_filename);
+    if (!fstab) {
+        printf("failed to open %s\n", fstab_filename);
+        return -1;
+    }
+
+    rc = get_crypt_ftr_and_key(&crypt_ftr);
+
+    return rc;
+}
+
 int cryptfs_check_passwd(char *passwd)
 {
     int rc = -1;
     char fstab_filename[PROPERTY_VALUE_MAX + sizeof(FSTAB_PREFIX)];
     char propbuf[PROPERTY_VALUE_MAX];
-    int i;
-    int flags;
 
     property_get("ro.hardware", propbuf, "");
     snprintf(fstab_filename, sizeof(fstab_filename), FSTAB_PREFIX"%s", propbuf);
diff --git a/crypto/jb/cryptfs.h b/crypto/jb/cryptfs.h
index 162159eb0..d815814d3 100644
--- a/crypto/jb/cryptfs.h
+++ b/crypto/jb/cryptfs.h
@@ -139,6 +139,7 @@ extern "C" {
   typedef void (*kdf_func)(char *passwd, unsigned char *salt, unsigned char *ikey, void *params);
 
   int cryptfs_crypto_complete(void);
+  int cryptfs_check_footer(void);
   int cryptfs_check_passwd(char *pw);
   int cryptfs_verify_passwd(char *newpw);
   int cryptfs_restart(void);
-- 
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