git/credential.c
Nikita Leonov 356c473295 credential: treat CR/LF as line endings in the credential protocol
This fix makes using Git credentials more friendly to Windows users: it
allows a credential helper to communicate using CR/LF line endings ("DOS
line endings" commonly found on Windows) instead of LF-only line endings
("Unix line endings").

Note that this changes the behavior a bit: if a credential helper
produces, say, a password with a trailing Carriage Return character,
that will now be culled even when the rest of the lines end only in Line
Feed characters, indicating that the Carriage Return was not meant to be
part of the line ending.

In practice, it seems _very_ unlikely that something like this happens.
Passwords usually need to consist of non-control characters, URLs need
to have special characters URL-encoded, and user names, well, are names.

However, it _does_ help on Windows, where CR/LF line endings are common:
as unrecognized commands are simply ignored by the credential machinery,
even a command like `quit\r` (which is clearly intended to abort) would
simply be ignored (silently) by Git.

So let's change the credential machinery to accept both CR/LF and LF
line endings.

While we do this for the credential helper protocol, we do _not_ adjust
`git credential-cache--daemon` (which won't work on Windows, anyway,
because it requires Unix sockets) nor `git credential-store` (which
writes the file `~/.git-credentials` which we consider an implementation
detail that should be opaque to the user, read: we do expect users _not_
to edit this file manually).

Signed-off-by: Nikita Leonov <nykyta.leonov@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-10-03 10:41:03 -07:00

513 lines
12 KiB
C

#include "cache.h"
#include "config.h"
#include "credential.h"
#include "string-list.h"
#include "run-command.h"
#include "url.h"
#include "prompt.h"
#include "sigchain.h"
#include "urlmatch.h"
void credential_init(struct credential *c)
{
memset(c, 0, sizeof(*c));
c->helpers.strdup_strings = 1;
}
void credential_clear(struct credential *c)
{
free(c->protocol);
free(c->host);
free(c->path);
free(c->username);
free(c->password);
string_list_clear(&c->helpers, 0);
credential_init(c);
}
int credential_match(const struct credential *want,
const struct credential *have)
{
#define CHECK(x) (!want->x || (have->x && !strcmp(want->x, have->x)))
return CHECK(protocol) &&
CHECK(host) &&
CHECK(path) &&
CHECK(username);
#undef CHECK
}
static int credential_from_potentially_partial_url(struct credential *c,
const char *url);
static int credential_config_callback(const char *var, const char *value,
void *data)
{
struct credential *c = data;
const char *key;
if (!skip_prefix(var, "credential.", &key))
return 0;
if (!value)
return config_error_nonbool(var);
if (!strcmp(key, "helper")) {
if (*value)
string_list_append(&c->helpers, value);
else
string_list_clear(&c->helpers, 0);
} else if (!strcmp(key, "username")) {
if (!c->username_from_proto) {
free(c->username);
c->username = xstrdup(value);
}
}
else if (!strcmp(key, "usehttppath"))
c->use_http_path = git_config_bool(var, value);
return 0;
}
static int proto_is_http(const char *s)
{
if (!s)
return 0;
return !strcmp(s, "https") || !strcmp(s, "http");
}
static void credential_describe(struct credential *c, struct strbuf *out);
static void credential_format(struct credential *c, struct strbuf *out);
static int select_all(const struct urlmatch_item *a,
const struct urlmatch_item *b)
{
return 0;
}
static int match_partial_url(const char *url, void *cb)
{
struct credential *c = cb;
struct credential want = CREDENTIAL_INIT;
int matches = 0;
if (credential_from_potentially_partial_url(&want, url) < 0)
warning(_("skipping credential lookup for key: credential.%s"),
url);
else
matches = credential_match(&want, c);
credential_clear(&want);
return matches;
}
static void credential_apply_config(struct credential *c)
{
char *normalized_url;
struct urlmatch_config config = { STRING_LIST_INIT_DUP };
struct strbuf url = STRBUF_INIT;
if (!c->host)
die(_("refusing to work with credential missing host field"));
if (!c->protocol)
die(_("refusing to work with credential missing protocol field"));
if (c->configured)
return;
config.section = "credential";
config.key = NULL;
config.collect_fn = credential_config_callback;
config.cascade_fn = NULL;
config.select_fn = select_all;
config.fallback_match_fn = match_partial_url;
config.cb = c;
credential_format(c, &url);
normalized_url = url_normalize(url.buf, &config.url);
git_config(urlmatch_config_entry, &config);
free(normalized_url);
strbuf_release(&url);
c->configured = 1;
if (!c->use_http_path && proto_is_http(c->protocol)) {
FREE_AND_NULL(c->path);
}
}
static void credential_describe(struct credential *c, struct strbuf *out)
{
if (!c->protocol)
return;
strbuf_addf(out, "%s://", c->protocol);
if (c->username && *c->username)
strbuf_addf(out, "%s@", c->username);
if (c->host)
strbuf_addstr(out, c->host);
if (c->path)
strbuf_addf(out, "/%s", c->path);
}
static void credential_format(struct credential *c, struct strbuf *out)
{
if (!c->protocol)
return;
strbuf_addf(out, "%s://", c->protocol);
if (c->username && *c->username) {
strbuf_add_percentencode(out, c->username, STRBUF_ENCODE_SLASH);
strbuf_addch(out, '@');
}
if (c->host)
strbuf_addstr(out, c->host);
if (c->path) {
strbuf_addch(out, '/');
strbuf_add_percentencode(out, c->path, 0);
}
}
static char *credential_ask_one(const char *what, struct credential *c,
int flags)
{
struct strbuf desc = STRBUF_INIT;
struct strbuf prompt = STRBUF_INIT;
char *r;
credential_describe(c, &desc);
if (desc.len)
strbuf_addf(&prompt, "%s for '%s': ", what, desc.buf);
else
strbuf_addf(&prompt, "%s: ", what);
r = git_prompt(prompt.buf, flags);
strbuf_release(&desc);
strbuf_release(&prompt);
return xstrdup(r);
}
static void credential_getpass(struct credential *c)
{
if (!c->username)
c->username = credential_ask_one("Username", c,
PROMPT_ASKPASS|PROMPT_ECHO);
if (!c->password)
c->password = credential_ask_one("Password", c,
PROMPT_ASKPASS);
}
int credential_read(struct credential *c, FILE *fp)
{
struct strbuf line = STRBUF_INIT;
while (strbuf_getline(&line, fp) != EOF) {
char *key = line.buf;
char *value = strchr(key, '=');
if (!line.len)
break;
if (!value) {
warning("invalid credential line: %s", key);
strbuf_release(&line);
return -1;
}
*value++ = '\0';
if (!strcmp(key, "username")) {
free(c->username);
c->username = xstrdup(value);
c->username_from_proto = 1;
} else if (!strcmp(key, "password")) {
free(c->password);
c->password = xstrdup(value);
} else if (!strcmp(key, "protocol")) {
free(c->protocol);
c->protocol = xstrdup(value);
} else if (!strcmp(key, "host")) {
free(c->host);
c->host = xstrdup(value);
} else if (!strcmp(key, "path")) {
free(c->path);
c->path = xstrdup(value);
} else if (!strcmp(key, "url")) {
credential_from_url(c, value);
} else if (!strcmp(key, "quit")) {
c->quit = !!git_config_bool("quit", value);
}
/*
* Ignore other lines; we don't know what they mean, but
* this future-proofs us when later versions of git do
* learn new lines, and the helpers are updated to match.
*/
}
strbuf_release(&line);
return 0;
}
static void credential_write_item(FILE *fp, const char *key, const char *value,
int required)
{
if (!value && required)
BUG("credential value for %s is missing", key);
if (!value)
return;
if (strchr(value, '\n'))
die("credential value for %s contains newline", key);
fprintf(fp, "%s=%s\n", key, value);
}
void credential_write(const struct credential *c, FILE *fp)
{
credential_write_item(fp, "protocol", c->protocol, 1);
credential_write_item(fp, "host", c->host, 1);
credential_write_item(fp, "path", c->path, 0);
credential_write_item(fp, "username", c->username, 0);
credential_write_item(fp, "password", c->password, 0);
}
static int run_credential_helper(struct credential *c,
const char *cmd,
int want_output)
{
struct child_process helper = CHILD_PROCESS_INIT;
FILE *fp;
strvec_push(&helper.args, cmd);
helper.use_shell = 1;
helper.in = -1;
if (want_output)
helper.out = -1;
else
helper.no_stdout = 1;
if (start_command(&helper) < 0)
return -1;
fp = xfdopen(helper.in, "w");
sigchain_push(SIGPIPE, SIG_IGN);
credential_write(c, fp);
fclose(fp);
sigchain_pop(SIGPIPE);
if (want_output) {
int r;
fp = xfdopen(helper.out, "r");
r = credential_read(c, fp);
fclose(fp);
if (r < 0) {
finish_command(&helper);
return -1;
}
}
if (finish_command(&helper))
return -1;
return 0;
}
static int credential_do(struct credential *c, const char *helper,
const char *operation)
{
struct strbuf cmd = STRBUF_INIT;
int r;
if (helper[0] == '!')
strbuf_addstr(&cmd, helper + 1);
else if (is_absolute_path(helper))
strbuf_addstr(&cmd, helper);
else
strbuf_addf(&cmd, "git credential-%s", helper);
strbuf_addf(&cmd, " %s", operation);
r = run_credential_helper(c, cmd.buf, !strcmp(operation, "get"));
strbuf_release(&cmd);
return r;
}
void credential_fill(struct credential *c)
{
int i;
if (c->username && c->password)
return;
credential_apply_config(c);
for (i = 0; i < c->helpers.nr; i++) {
credential_do(c, c->helpers.items[i].string, "get");
if (c->username && c->password)
return;
if (c->quit)
die("credential helper '%s' told us to quit",
c->helpers.items[i].string);
}
credential_getpass(c);
if (!c->username && !c->password)
die("unable to get password from user");
}
void credential_approve(struct credential *c)
{
int i;
if (c->approved)
return;
if (!c->username || !c->password)
return;
credential_apply_config(c);
for (i = 0; i < c->helpers.nr; i++)
credential_do(c, c->helpers.items[i].string, "store");
c->approved = 1;
}
void credential_reject(struct credential *c)
{
int i;
credential_apply_config(c);
for (i = 0; i < c->helpers.nr; i++)
credential_do(c, c->helpers.items[i].string, "erase");
FREE_AND_NULL(c->username);
FREE_AND_NULL(c->password);
c->approved = 0;
}
static int check_url_component(const char *url, int quiet,
const char *name, const char *value)
{
if (!value)
return 0;
if (!strchr(value, '\n'))
return 0;
if (!quiet)
warning(_("url contains a newline in its %s component: %s"),
name, url);
return -1;
}
/*
* Potentially-partial URLs can, but do not have to, contain
*
* - a protocol (or scheme) of the form "<protocol>://"
*
* - a host name (the part after the protocol and before the first slash after
* that, if any)
*
* - a user name and potentially a password (as "<user>[:<password>]@" part of
* the host name)
*
* - a path (the part after the host name, if any, starting with the slash)
*
* Missing parts will be left unset in `struct credential`. Thus, `https://`
* will have only the `protocol` set, `example.com` only the host name, and
* `/git` only the path.
*
* Note that an empty host name in an otherwise fully-qualified URL (e.g.
* `cert:///path/to/cert.pem`) will be treated as unset if we expect the URL to
* be potentially partial, and only then (otherwise, the empty string is used).
*
* The credential_from_url() function does not allow partial URLs.
*/
static int credential_from_url_1(struct credential *c, const char *url,
int allow_partial_url, int quiet)
{
const char *at, *colon, *cp, *slash, *host, *proto_end;
credential_clear(c);
/*
* Match one of:
* (1) proto://<host>/...
* (2) proto://<user>@<host>/...
* (3) proto://<user>:<pass>@<host>/...
*/
proto_end = strstr(url, "://");
if (!allow_partial_url && (!proto_end || proto_end == url)) {
if (!quiet)
warning(_("url has no scheme: %s"), url);
return -1;
}
cp = proto_end ? proto_end + 3 : url;
at = strchr(cp, '@');
colon = strchr(cp, ':');
/*
* A query or fragment marker before the slash ends the host portion.
* We'll just continue to call this "slash" for simplicity. Notably our
* "trim leading slashes" part won't skip over this part of the path,
* but that's what we'd want.
*/
slash = cp + strcspn(cp, "/?#");
if (!at || slash <= at) {
/* Case (1) */
host = cp;
}
else if (!colon || at <= colon) {
/* Case (2) */
c->username = url_decode_mem(cp, at - cp);
if (c->username && *c->username)
c->username_from_proto = 1;
host = at + 1;
} else {
/* Case (3) */
c->username = url_decode_mem(cp, colon - cp);
if (c->username && *c->username)
c->username_from_proto = 1;
c->password = url_decode_mem(colon + 1, at - (colon + 1));
host = at + 1;
}
if (proto_end && proto_end - url > 0)
c->protocol = xmemdupz(url, proto_end - url);
if (!allow_partial_url || slash - host > 0)
c->host = url_decode_mem(host, slash - host);
/* Trim leading and trailing slashes from path */
while (*slash == '/')
slash++;
if (*slash) {
char *p;
c->path = url_decode(slash);
p = c->path + strlen(c->path) - 1;
while (p > c->path && *p == '/')
*p-- = '\0';
}
if (check_url_component(url, quiet, "username", c->username) < 0 ||
check_url_component(url, quiet, "password", c->password) < 0 ||
check_url_component(url, quiet, "protocol", c->protocol) < 0 ||
check_url_component(url, quiet, "host", c->host) < 0 ||
check_url_component(url, quiet, "path", c->path) < 0)
return -1;
return 0;
}
static int credential_from_potentially_partial_url(struct credential *c,
const char *url)
{
return credential_from_url_1(c, url, 1, 0);
}
int credential_from_url_gently(struct credential *c, const char *url, int quiet)
{
return credential_from_url_1(c, url, 0, quiet);
}
void credential_from_url(struct credential *c, const char *url)
{
if (credential_from_url_gently(c, url, 0) < 0)
die(_("credential url cannot be parsed: %s"), url);
}