AU: Switch signature verification from external openssl to library.
This avoids writing data to temp files, invoking an external process and reading
data from temporary files. This is cleaner, and improves marginally performance
and security.
BUG=9928
TEST=unit tests, emerge-arm-generic
Change-Id: I7b7d6632e23a1cbcc9a281f883279555583dd344
Review URL: http://codereview.chromium.org/5633001
diff --git a/payload_signer.cc b/payload_signer.cc
index de80a5b..40bfcfc 100644
--- a/payload_signer.cc
+++ b/payload_signer.cc
@@ -4,8 +4,10 @@
#include "update_engine/payload_signer.h"
-#include "base/logging.h"
-#include "base/string_util.h"
+#include <base/logging.h>
+#include <base/string_util.h>
+#include <openssl/pem.h>
+
#include "update_engine/omaha_hash_calculator.h"
#include "update_engine/subprocess.h"
#include "update_engine/update_metadata.pb.h"
@@ -115,34 +117,40 @@
TEST_AND_RETURN_FALSE(sig_index < signatures.signatures_size());
const Signatures_Signature& signature = signatures.signatures(sig_index);
- const string sig_data = signature.data();
- string sig_path;
- TEST_AND_RETURN_FALSE(
- utils::MakeTempFile("/var/run/signature.XXXXXX", &sig_path, NULL));
- ScopedPathUnlinker sig_path_unlinker(sig_path);
- TEST_AND_RETURN_FALSE(utils::WriteFile(sig_path.c_str(),
- &sig_data[0],
- sig_data.size()));
- string hash_path;
- TEST_AND_RETURN_FALSE(
- utils::MakeTempFile("/var/run/hash.XXXXXX", &hash_path, NULL));
- ScopedPathUnlinker hash_path_unlinker(hash_path);
+ const string& sig_data = signature.data();
- // TODO(petkov): This runs on the client so it will be cleaner if it uses
- // direct openssl library calls.
- vector<string> cmd;
- SplitString("/usr/bin/openssl rsautl -verify -pubin -inkey x -in x -out x",
- ' ',
- &cmd);
- cmd[cmd.size() - 5] = public_key_path;
- cmd[cmd.size() - 3] = sig_path;
- cmd[cmd.size() - 1] = hash_path;
+ // The code below executes the equivalent of:
+ //
+ // openssl rsautl -verify -pubin -inkey |public_key_path|
+ // -in |sig_data| -out |out_hash_data|
- int return_code = 0;
- TEST_AND_RETURN_FALSE(Subprocess::SynchronousExec(cmd, &return_code));
- TEST_AND_RETURN_FALSE(return_code == 0);
+ // Loads the public key.
+ FILE* fpubkey = fopen(public_key_path.c_str(), "rb");
+ TEST_AND_RETURN_FALSE(fpubkey != NULL);
+ char dummy_password[] = { ' ', 0 }; // Ensure no password is read from stdin.
+ RSA* rsa = PEM_read_RSA_PUBKEY(fpubkey, NULL, NULL, dummy_password);
+ fclose(fpubkey);
+ TEST_AND_RETURN_FALSE(rsa != NULL);
+ unsigned int keysize = RSA_size(rsa);
+ if (sig_data.size() > 2 * keysize) {
+ LOG(ERROR) << "Signature size is too big for public key size.";
+ RSA_free(rsa);
+ return false;
+ }
- TEST_AND_RETURN_FALSE(utils::ReadFile(hash_path, out_hash_data));
+ // Decrypts the signature.
+ vector<char> hash_data(keysize);
+ int decrypt_size = RSA_public_decrypt(
+ sig_data.size(),
+ reinterpret_cast<const unsigned char*>(sig_data.data()),
+ reinterpret_cast<unsigned char*>(hash_data.data()),
+ rsa,
+ RSA_PKCS1_PADDING);
+ RSA_free(rsa);
+ TEST_AND_RETURN_FALSE(decrypt_size > 0 &&
+ decrypt_size <= static_cast<int>(hash_data.size()));
+ hash_data.resize(decrypt_size);
+ out_hash_data->swap(hash_data);
return true;
}