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[PATCH 12/13] credentials: add "store" helper

From
Jeff King <peff@peff.net>
Date
Nov 24, 2011, 11:07 UTC
Message-ID
<20111124110756.GJ8417@sigill.intra.peff.net>
In-Reply-To
<20111124105801.GA6168@sigill.intra.peff.net>

This is like "cache", except that we actually put the credentials on disk. This can be terribly insecure, of course, but we do what we can to protect them by filesystem permissions, and we warn the user in the documentation.

This is not unlike using .netrc to store entries, but it's a little more user-friendly. Instead of putting credentials in place ahead of time, we transparently store them after prompting the user for them once.

Signed-off-by: Jeff King <peff@peff.net>
---
 .gitignore                             |    1 +
 Documentation/git-credential-store.txt |   75 +++++++++++++++++
 Documentation/gitcredentials.txt       |    5 +
 Makefile                               |    1 +
 credential-store.c                     |  144 ++++++++++++++++++++++++++++++++
 t/t0302-credential-store.sh            |    9 ++
 6 files changed, 235 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/git-credential-store.txt
 create mode 100644 credential-store.c
 create mode 100755 t/t0302-credential-store.sh
diff --git a/.gitignore b/.gitignore
index a6b0bd4..2b7a3f9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -32,6 +32,7 @@
 /git-count-objects
 /git-credential-cache
 /git-credential-cache--daemon
+/git-credential-store
 /git-cvsexportcommit
 /git-cvsimport
 /git-cvsserver
diff --git a/Documentation/git-credential-store.txt b/Documentation/git-credential-store.txt
new file mode 100644
index 0000000..3dcffbd
--- /dev/null
+++ b/Documentation/git-credential-store.txt
@@ -0,0 +1,75 @@
+git-credential-store(1)
+=======================
+
+NAME
+----
+git-credential-store - helper to store credentials on disk
+
+SYNOPSIS
+--------
+-------------------
+git config credential.helper 'store [options]'
+-------------------
+
+DESCRIPTION
+-----------
+
+NOTE: Using this helper will store your passwords unencrypted on disk,
+protected only by filesystem permissions. If this is not an acceptable
+security tradeoff, try linkgit:git-credential-cache[1], or find a helper
+that integrates with secure storage provided by your operating system.
+
+This command stores credentials indefinitely on disk for use by future
+git programs.
+
+You probably don't want to invoke this command directly; it is meant to
+be used as a credential helper by other parts of git. See
+linkgit:gitcredentials[7] or `EXAMPLES` below.
+
+OPTIONS
+-------
+
+--store=<path>::
+
+	Use `<path>` to store credentials. The file will have its
+	filesystem permissions set to prevent other users on the system
+	from reading it, but will not be encrypted or otherwise
+	protected. Defaults to `~/.git-credentials`.
+
+EXAMPLES
+--------
+
+The point of this helper is to reduce the number of times you must type
+your username or password. For example:
+
+------------------------------------------
+$ git config credential.helper store
+$ git push http://example.com/repo.git
+Username: <type your username>
+Password: <type your password>
+
+[several days later]
+$ git push http://example.com/repo.git
+[your credentials are used automatically]
+------------------------------------------
+
+STORAGE FORMAT
+--------------
+
+The `.git-credentials` file is stored in plaintext. Each credential is
+stored on its own line as a URL like:
+
+------------------------------
+https://user:pass@example.com
+------------------------------
+
+When git needs authentication for a particular context URL context,
+credential-store will consider that context a pattern to match against
+each entry in the credentials file.  If the protocol, hostname, and
+username (if we already have one) match, then the password is returned
+to git. See the discussion of configuration in linkgit:gitcredentials[7]
+for more information.
+
+GIT
+---
+Part of the linkgit:git[1] suite
diff --git a/Documentation/gitcredentials.txt b/Documentation/gitcredentials.txt
index a1592ed..519d2bb 100644
--- a/Documentation/gitcredentials.txt
+++ b/Documentation/gitcredentials.txt
@@ -71,6 +71,11 @@ cache::
 	Cache credentials in memory for a short period of time. See
 	linkgit:git-credential-cache[1] for details.
 
+store::
+
+	Store credentials indefinitely on disk. See
+	linkgit:git-credential-store[1] for details.
+
 You may may also have third-party helpers installed; search for
 `credential-*` in the output of `git help -a`, and consult the
 documentation of individual helpers.  Once you have selected a helper,
diff --git a/Makefile b/Makefile
index 5d41c29..2537128 100644
--- a/Makefile
+++ b/Makefile
@@ -429,6 +429,7 @@ PROGRAM_OBJS += http-backend.o
 PROGRAM_OBJS += sh-i18n--envsubst.o
 PROGRAM_OBJS += credential-cache.o
 PROGRAM_OBJS += credential-cache--daemon.o
+PROGRAM_OBJS += credential-store.o
 
 PROGRAMS += $(patsubst %.o,git-%$X,$(PROGRAM_OBJS))
 
diff --git a/credential-store.c b/credential-store.c
new file mode 100644
index 0000000..a6ddb0c
--- /dev/null
+++ b/credential-store.c
@@ -0,0 +1,144 @@
+#include "cache.h"
+#include "credential.h"
+#include "string-list.h"
+#include "parse-options.h"
+
+static struct lock_file credential_lock;
+
+static void parse_credential_file(const char *fn,
+				  struct credential *c,
+				  void (*match_cb)(struct credential *),
+				  void (*other_cb)(struct strbuf *))
+{
+	FILE *fh;
+	struct strbuf line = STRBUF_INIT;
+	struct credential entry = CREDENTIAL_INIT;
+
+	fh = fopen(fn, "r");
+	if (!fh) {
+		if (errno != ENOENT)
+			die_errno("unable to open %s", fn);
+		return;
+	}
+
+	while (strbuf_getline(&line, fh, '\n') != EOF) {
+		credential_from_url(&entry, line.buf);
+		if (entry.username && entry.password &&
+		    credential_match(c, &entry)) {
+			if (match_cb) {
+				match_cb(&entry);
+				break;
+			}
+		}
+		else if (other_cb)
+			other_cb(&line);
+	}
+
+	credential_clear(&entry);
+	strbuf_release(&line);
+	fclose(fh);
+}
+
+static void print_entry(struct credential *c)
+{
+	printf("username=%s\n", c->username);
+	printf("password=%s\n", c->password);
+}
+
+static void print_line(struct strbuf *buf)
+{
+	strbuf_addch(buf, '\n');
+	write_or_die(credential_lock.fd, buf->buf, buf->len);
+}
+
+static void rewrite_credential_file(const char *fn, struct credential *c,
+				    struct strbuf *extra)
+{
+	umask(077);
+	if (hold_lock_file_for_update(&credential_lock, fn, 0) < 0)
+		die_errno("unable to get credential storage lock");
+	parse_credential_file(fn, c, NULL, print_line);
+	if (extra)
+		print_line(extra);
+	if (commit_lock_file(&credential_lock) < 0)
+		die_errno("unable to commit credential store");
+}
+
+static void store_credential(const char *fn, struct credential *c)
+{
+	struct strbuf buf = STRBUF_INIT;
+
+	if (!c->protocol || !(c->host || c->path) ||
+	    !c->username || !c->password)
+		return;
+
+	strbuf_addf(&buf, "%s://", c->protocol);
+	strbuf_addstr_urlencode(&buf, c->username, 1);
+	strbuf_addch(&buf, ':');
+	strbuf_addstr_urlencode(&buf, c->password, 1);
+	strbuf_addch(&buf, '@');
+	if (c->host)
+		strbuf_addstr_urlencode(&buf, c->host, 1);
+	if (c->path) {
+		strbuf_addch(&buf, '/');
+		strbuf_addstr_urlencode(&buf, c->path, 0);
+	}
+
+	rewrite_credential_file(fn, c, &buf);
+	strbuf_release(&buf);
+}
+
+static void remove_credential(const char *fn, struct credential *c)
+{
+	if (!c->protocol || !(c->host || c->path))
+		return;
+	rewrite_credential_file(fn, c, NULL);
+}
+
+static int lookup_credential(const char *fn, struct credential *c)
+{
+	if (!c->protocol || !(c->host || c->path))
+		return 0;
+	parse_credential_file(fn, c, print_entry, NULL);
+	return c->username && c->password;
+}
+
+int main(int argc, const char **argv)
+{
+	const char * const usage[] = {
+		"git credential-store [options] <action>",
+		NULL
+	};
+	const char *op;
+	struct credential c = CREDENTIAL_INIT;
+	char *store = NULL;
+	struct option options[] = {
+		OPT_STRING_LIST(0, "store", &store, "file",
+				"fetch and store credentials in <file>"),
+		OPT_END()
+	};
+
+	argc = parse_options(argc, argv, NULL, options, usage, 0);
+	if (argc != 1)
+		usage_with_options(usage, options);
+	op = argv[0];
+
+	if (!store)
+		store = expand_user_path("~/.git-credentials");
+	if (!store)
+		die("unable to set up default store; use --store");
+
+	if (credential_read(&c, stdin) < 0)
+		die("unable to read credential");
+
+	if (!strcmp(op, "get"))
+		lookup_credential(store, &c);
+	else if (!strcmp(op, "erase"))
+		remove_credential(store, &c);
+	else if (!strcmp(op, "store"))
+		store_credential(store, &c);
+	else
+		die("unknown operation: %s", op);
+
+	return 0;
+}
diff --git a/t/t0302-credential-store.sh b/t/t0302-credential-store.sh
new file mode 100755
index 0000000..f61b40c
--- /dev/null
+++ b/t/t0302-credential-store.sh
@@ -0,0 +1,9 @@
+#!/bin/sh
+
+test_description='credential-store tests'
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-credential.sh
+
+helper_test store
+
+test_done

-- 
1.7.7.4.5.gb32a5
Previous: René ScharfeNext: Eric Sunshine
Message 26 of 49 in “credential helpers, take two”
  1. 0/13 credential helpers, take twoJeff King, Nov 24, 2011
  2. 01/13 test-lib: add test_config_global variantJeff King, Nov 24, 2011
  3. 02/13 t5550: fix typoJeff King, Nov 24, 2011
  4. 03/13 introduce credentials APIJeff King, Nov 24, 2011
  5. Junio C HamanoNov 28, 2011
  6. Jeff KingNov 29, 2011
  7. Junio C HamanoNov 29, 2011
  8. Jeff KingNov 29, 2011
  9. 04/13 credential: add function for parsing url componentsJeff King, Nov 24, 2011
  10. 05/13 http: use credential API to get passwordsJeff King, Nov 24, 2011
  11. 06/13 credential: apply helper configJeff King, Nov 24, 2011
  12. 07/13 credential: add credential.*.usernameJeff King, Nov 24, 2011
  13. 08/13 credential: make relevance of http path configurableJeff King, Nov 24, 2011
  14. 09/13 docs: end-user documentation for the credential subsystemJeff King, Nov 24, 2011
  15. 10/13 credentials: add "cache" helperJeff King, Nov 24, 2011
  16. Eric SunshineNov 24, 2011
  17. Junio C HamanoNov 29, 2011
  18. Jeff KingNov 29, 2011
  19. 11/13 strbuf: add strbuf_add*_urlencodeJeff King, Nov 24, 2011
  20. Junio C HamanoNov 29, 2011
  21. Jeff KingNov 29, 2011
  22. René ScharfeNov 29, 2011
  23. Jeff KingNov 30, 2011
  24. Junio C HamanoNov 30, 2011
  25. René ScharfeNov 30, 2011
  26. 12/13 credentials: add "store" helperJeff King, Nov 24, 2011
  27. Eric SunshineNov 24, 2011
  28. Jeff KingNov 24, 2011
  29. Junio C HamanoNov 29, 2011
  30. Jeff KingNov 29, 2011
  31. 13/13 t: add test harness for external credential helpersJeff King, Nov 24, 2011
  32. Erik Faye-LundNov 24, 2011
  33. Jeff KingNov 24, 2011
  34. Erik Faye-LundNov 24, 2011
  35. 0/6 echo usernames as they are typedJeff King, Nov 27, 2011
  36. 1/6 move git_getpass to its own source fileJeff King, Nov 27, 2011
  37. 2/6 refactor git_getpass into generic prompt functionJeff King, Nov 27, 2011
  38. 3/6 stub out getpass_echo functionJeff King, Nov 27, 2011
  39. 4/6 prompt: add PROMPT_ECHO flagJeff King, Nov 27, 2011
  40. 5/6 credential: use git_prompt instead of git_getpassJeff King, Nov 27, 2011
  41. 6/6 compat/getpass: add a /dev/tty implementationJeff King, Nov 27, 2011
  42. Junio C HamanoNov 27, 2011
  43. Erik Faye-LundNov 27, 2011
  44. Jeff KingNov 28, 2011
  45. Erik Faye-LundNov 28, 2011
  46. Jeff KingNov 28, 2011
  47. Frans KlaverNov 28, 2011
  48. Erik Faye-LundNov 28, 2011
  49. Jeff KingNov 28, 2011

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