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cryptfs: check for errors in create_encrypted_random_key()

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When generating the key and salt we weren't checking for an error
opening or reading from /dev/urandom.  Switch to the helper function
ReadRandomBytes() and start checking for errors.

Test: Booted device with FDE.  As a extra sanity check I also
      temporarily added log messages that dump the key and salt,
      and I verified they still appear random.
Change-Id: I01ccee4f1f9910bf9508c8f02a918157393b0e68
This commit is contained in:
Eric Biggers 2019-01-16 13:05:34 -08:00
parent 0ef7bfd59c
commit 3a2f7db477
1 changed files with 7 additions and 6 deletions
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13
cryptfs.cpp
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@ -1398,14 +1398,15 @@ static int decrypt_master_key(const char* passwd, unsigned char* decrypted_maste
static int create_encrypted_random_key(const char* passwd, unsigned char* master_key,
unsigned char* salt, struct crypt_mnt_ftr* crypt_ftr) {
int fd;
unsigned char key_buf[MAX_KEY_LEN];
/* Get some random bits for a key */
fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC);
read(fd, key_buf, sizeof(key_buf));
read(fd, salt, SALT_LEN);
close(fd);
/* Get some random bits for a key and salt */
if (android::vold::ReadRandomBytes(sizeof(key_buf), reinterpret_cast<char*>(key_buf)) != 0) {
return -1;
}
if (android::vold::ReadRandomBytes(SALT_LEN, reinterpret_cast<char*>(salt)) != 0) {
return -1;
}
/* Now encrypt it with the password */
return encrypt_master_key(passwd, salt, key_buf, master_key, crypt_ftr);