thodg/libgit2/src/transports/cred.c

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• Hash : bd270b70
  Author :
  Date : 2014-04-18T17:08:10
  

  cred: tighten username rules The ssh-specific credentials allow the username to be missing. The idea being that the ssh transport will then use the username provided in the url, if it's available. There are two main issues with this. The credential callback already knows what username was provided by the url and needs to figure out whether it wants to ask the user for it or it can reuse it, so passing NULL as the username means the credential callback is suspicious. The username provided in the url is not in fact used by the transport. The only time it even considers it is for the user/pass credential, which asserts the existence of a username in its constructor. For the ssh-specific ones, it passes in the username stored in the credential, which is NULL. The libssh2 macro we use runs strlen() against this value (which is no different from what we would be doing ourselves), so we then crash. As the documentation doesn't suggest to leave out the username, assert the need for a username in the code, which removes this buggy behavior and removes implicit state. git_cred_has_username() becomes a blacklist of credential types that do not have a username. The only one at the moment is the 'default' one, which is meant to call up some Microsoft magic.

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• src/transports/cred.c

• /*
   * Copyright (C) the libgit2 contributors. All rights reserved.
   *
   * This file is part of libgit2, distributed under the GNU GPL v2 with
   * a Linking Exception. For full terms see the included COPYING file.
   */
  
  #include "git2.h"
  #include "smart.h"
  #include "git2/cred_helpers.h"
  
  int git_cred_has_username(git_cred *cred)
  {
  	if (cred->credtype == GIT_CREDTYPE_DEFAULT)
  		return 0;
  
  	return 1;
  }
  
  static void plaintext_free(struct git_cred *cred)
  {
  	git_cred_userpass_plaintext *c = (git_cred_userpass_plaintext *)cred;
  
  	git__free(c->username);
  
  	/* Zero the memory which previously held the password */
  	if (c->password) {
  		size_t pass_len = strlen(c->password);
  		git__memzero(c->password, pass_len);
  		git__free(c->password);
  	}
  
  	git__memzero(c, sizeof(*c));
  	git__free(c);
  }
  
  int git_cred_userpass_plaintext_new(
  	git_cred **cred,
  	const char *username,
  	const char *password)
  {
  	git_cred_userpass_plaintext *c;
  
  	assert(cred && username && password);
  
  	c = git__malloc(sizeof(git_cred_userpass_plaintext));
  	GITERR_CHECK_ALLOC(c);
  
  	c->parent.credtype = GIT_CREDTYPE_USERPASS_PLAINTEXT;
  	c->parent.free = plaintext_free;
  	c->username = git__strdup(username);
  
  	if (!c->username) {
  		git__free(c);
  		return -1;
  	}
  
  	c->password = git__strdup(password);
  
  	if (!c->password) {
  		git__free(c->username);
  		git__free(c);
  		return -1;
  	}
  
  	*cred = &c->parent;
  	return 0;
  }
  
  static void ssh_key_free(struct git_cred *cred)
  {
  	git_cred_ssh_key *c =
  		(git_cred_ssh_key *)cred;
  
  	git__free(c->username);
  	git__free(c->publickey);
  	git__free(c->privatekey);
  
  	if (c->passphrase) {
  		/* Zero the memory which previously held the passphrase */
  		size_t pass_len = strlen(c->passphrase);
  		git__memzero(c->passphrase, pass_len);
  		git__free(c->passphrase);
  	}
  
  	git__memzero(c, sizeof(*c));
  	git__free(c);
  }
  
  static void ssh_custom_free(struct git_cred *cred)
  {
  	git_cred_ssh_custom *c = (git_cred_ssh_custom *)cred;
  
  	git__free(c->username);
  	git__free(c->publickey);
  
  	git__memzero(c, sizeof(*c));
  	git__free(c);
  }
  
  static void default_free(struct git_cred *cred)
  {
  	git_cred_default *c = (git_cred_default *)cred;
  
  	git__free(c);
  }
  
  int git_cred_ssh_key_new(
  	git_cred **cred,
  	const char *username,
  	const char *publickey,
  	const char *privatekey,
  	const char *passphrase)
  {
  	git_cred_ssh_key *c;
  
  	assert(username && cred && privatekey);
  
  	c = git__calloc(1, sizeof(git_cred_ssh_key));
  	GITERR_CHECK_ALLOC(c);
  
  	c->parent.credtype = GIT_CREDTYPE_SSH_KEY;
  	c->parent.free = ssh_key_free;
  
  	c->username = git__strdup(username);
  	GITERR_CHECK_ALLOC(c->username);
  
  	c->privatekey = git__strdup(privatekey);
  	GITERR_CHECK_ALLOC(c->privatekey);
  
  	if (publickey) {
  		c->publickey = git__strdup(publickey);
  		GITERR_CHECK_ALLOC(c->publickey);
  	}
  
  	if (passphrase) {
  		c->passphrase = git__strdup(passphrase);
  		GITERR_CHECK_ALLOC(c->passphrase);
  	}
  
  	*cred = &c->parent;
  	return 0;
  }
  
  int git_cred_ssh_key_from_agent(git_cred **cred, const char *username) {
  	git_cred_ssh_key *c;
  
  	assert(username && cred);
  
  	c = git__calloc(1, sizeof(git_cred_ssh_key));
  	GITERR_CHECK_ALLOC(c);
  
  	c->parent.credtype = GIT_CREDTYPE_SSH_KEY;
  	c->parent.free = ssh_key_free;
  
  	c->username = git__strdup(username);
  	GITERR_CHECK_ALLOC(c->username);
  
  	c->privatekey = NULL;
  
  	*cred = &c->parent;
  	return 0;
  }
  
  int git_cred_ssh_custom_new(
  	git_cred **cred,
  	const char *username,
  	const char *publickey,
  	size_t publickey_len,
  	git_cred_sign_callback sign_callback,
  	void *sign_data)
  {
  	git_cred_ssh_custom *c;
  
  	assert(username && cred);
  
  	c = git__calloc(1, sizeof(git_cred_ssh_custom));
  	GITERR_CHECK_ALLOC(c);
  
  	c->parent.credtype = GIT_CREDTYPE_SSH_CUSTOM;
  	c->parent.free = ssh_custom_free;
  
  	c->username = git__strdup(username);
  	GITERR_CHECK_ALLOC(c->username);
  
  	if (publickey_len > 0) {
  		c->publickey = git__malloc(publickey_len);
  		GITERR_CHECK_ALLOC(c->publickey);
  
  		memcpy(c->publickey, publickey, publickey_len);
  	}
  
  	c->publickey_len = publickey_len;
  	c->sign_callback = sign_callback;
  	c->sign_data = sign_data;
  
  	*cred = &c->parent;
  	return 0;
  }
  
  int git_cred_default_new(git_cred **cred)
  {
  	git_cred_default *c;
  
  	assert(cred);
  
  	c = git__calloc(1, sizeof(git_cred_default));
  	GITERR_CHECK_ALLOC(c);
  
  	c->credtype = GIT_CREDTYPE_DEFAULT;
  	c->free = default_free;
  
  	*cred = c;
  	return 0;
  }
  

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