auth: add basic authentication filter framework

This leverages the new lua support. See
filters/simple-authentication.lua for explaination of how this works.
There is also additional documentation in cgitrc.5.txt.

Though this is a cookie-based approach, cgit's caching mechanism is
preserved for authenticated pages.

Very plugable and extendable depending on user needs.

The sample script uses an HMAC-SHA1 based cookie to store the
currently logged in user, with an expiration date.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Jason A. Donenfeld 2014-01-14 21:49:31 +01:00
parent 3741254a69
commit d6e9200cc3
6 changed files with 387 additions and 16 deletions

96
cgit.c
View File

@ -192,6 +192,8 @@ static void config_cb(const char *name, const char *value)
ctx.cfg.commit_filter = cgit_new_filter(value, COMMIT);
else if (!strcmp(name, "email-filter"))
ctx.cfg.email_filter = cgit_new_filter(value, EMAIL);
else if (!strcmp(name, "auth-filter"))
ctx.cfg.auth_filter = cgit_new_filter(value, AUTH);
else if (!strcmp(name, "embedded"))
ctx.cfg.embedded = atoi(value);
else if (!strcmp(name, "max-atom-items"))
@ -378,6 +380,10 @@ static void prepare_context(struct cgit_context *ctx)
ctx->env.script_name = getenv("SCRIPT_NAME");
ctx->env.server_name = getenv("SERVER_NAME");
ctx->env.server_port = getenv("SERVER_PORT");
ctx->env.http_cookie = getenv("HTTP_COOKIE");
ctx->env.http_referer = getenv("HTTP_REFERER");
ctx->env.content_length = getenv("CONTENT_LENGTH") ? strtoul(getenv("CONTENT_LENGTH"), NULL, 10) : 0;
ctx->env.authenticated = 0;
ctx->page.mimetype = "text/html";
ctx->page.charset = PAGE_ENCODING;
ctx->page.filename = NULL;
@ -593,11 +599,92 @@ static int prepare_repo_cmd(struct cgit_context *ctx)
return 0;
}
static inline void open_auth_filter(struct cgit_context *ctx, const char *function)
{
cgit_open_filter(ctx->cfg.auth_filter, function,
ctx->env.http_cookie ? ctx->env.http_cookie : "",
ctx->env.request_method ? ctx->env.request_method : "",
ctx->env.query_string ? ctx->env.query_string : "",
ctx->env.http_referer ? ctx->env.http_referer : "",
ctx->env.path_info ? ctx->env.path_info : "",
ctx->env.http_host ? ctx->env.http_host : "",
ctx->env.https ? ctx->env.https : "",
ctx->qry.repo ? ctx->qry.repo : "",
ctx->qry.page ? ctx->qry.page : "",
ctx->qry.url ? ctx->qry.url : "");
}
#define MAX_AUTHENTICATION_POST_BYTES 4096
static inline void authenticate_post(struct cgit_context *ctx)
{
if (ctx->env.http_referer && strlen(ctx->env.http_referer) > 0) {
html("Status: 302 Redirect\n");
html("Cache-Control: no-cache, no-store\n");
htmlf("Location: %s\n", ctx->env.http_referer);
} else {
html("Status: 501 Missing Referer\n");
html("Cache-Control: no-cache, no-store\n\n");
exit(0);
}
open_auth_filter(ctx, "authenticate-post");
char buffer[MAX_AUTHENTICATION_POST_BYTES];
int len;
len = ctx->env.content_length;
if (len > MAX_AUTHENTICATION_POST_BYTES)
len = MAX_AUTHENTICATION_POST_BYTES;
if (read(STDIN_FILENO, buffer, len) < 0)
die_errno("Could not read POST from stdin");
if (write(STDOUT_FILENO, buffer, len) < 0)
die_errno("Could not write POST to stdout");
/* The filter may now spit out a Set-Cookie: ... */
cgit_close_filter(ctx->cfg.auth_filter);
html("\n");
exit(0);
}
static inline void authenticate_cookie(struct cgit_context *ctx)
{
/* If we don't have an auth_filter, consider all cookies valid, and thus return early. */
if (!ctx->cfg.auth_filter) {
ctx->env.authenticated = 1;
return;
}
/* If we're having something POST'd to /login, we're authenticating POST,
* instead of the cookie, so call authenticate_post and bail out early.
* This pattern here should match /?p=login with POST. */
if (ctx->env.request_method && ctx->qry.page && !ctx->repo && \
!strcmp(ctx->env.request_method, "POST") && !strcmp(ctx->qry.page, "login")) {
authenticate_post(ctx);
return;
}
/* If we've made it this far, we're authenticating the cookie for real, so do that. */
open_auth_filter(ctx, "authenticate-cookie");
ctx->env.authenticated = cgit_close_filter(ctx->cfg.auth_filter);
}
static void process_request(void *cbdata)
{
struct cgit_context *ctx = cbdata;
struct cgit_cmd *cmd;
/* If we're not yet authenticated, no matter what page we're on,
* display the authentication body from the auth_filter. This should
* never be cached. */
if (!ctx->env.authenticated) {
ctx->page.title = "Authentication Required";
cgit_print_http_headers(ctx);
cgit_print_docstart(ctx);
cgit_print_pageheader(ctx);
open_auth_filter(ctx, "body");
cgit_close_filter(ctx->cfg.auth_filter);
cgit_print_docend();
return;
}
cmd = cgit_get_cmd(ctx);
if (!cmd) {
ctx->page.title = "cgit error";
@ -911,6 +998,7 @@ int main(int argc, const char **argv)
int err, ttl;
cgit_init_filters();
atexit(cgit_cleanup_filters);
prepare_context(&ctx);
cgit_repolist.length = 0;
@ -948,18 +1036,22 @@ int main(int argc, const char **argv)
cgit_parse_url(ctx.qry.url);
}
/* Before we go any further, we set ctx.env.authenticated by checking to see
* if the supplied cookie is valid. All cookies are valid if there is no
* auth_filter. If there is an auth_filter, the filter decides. */
authenticate_cookie(&ctx);
ttl = calc_ttl();
if (ttl < 0)
ctx.page.expires += 10 * 365 * 24 * 60 * 60; /* 10 years */
else
ctx.page.expires += ttl * 60;
if (ctx.env.request_method && !strcmp(ctx.env.request_method, "HEAD"))
if (!ctx.env.authenticated || (ctx.env.request_method && !strcmp(ctx.env.request_method, "HEAD")))
ctx.cfg.nocache = 1;
if (ctx.cfg.nocache)
ctx.cfg.cache_size = 0;
err = cache_process(ctx.cfg.cache_size, ctx.cfg.cache_root,
ctx.qry.raw, ttl, process_request, &ctx);
cgit_cleanup_filters();
if (err)
cgit_print_error("Error processing page: %s (%d)",
strerror(err), err);

7
cgit.h
View File

@ -53,7 +53,7 @@ typedef void (*filepair_fn)(struct diff_filepair *pair);
typedef void (*linediff_fn)(char *line, int len);
typedef enum {
ABOUT, COMMIT, SOURCE, EMAIL
ABOUT, COMMIT, SOURCE, EMAIL, AUTH
} filter_type;
struct cgit_filter {
@ -252,6 +252,7 @@ struct cgit_config {
struct cgit_filter *commit_filter;
struct cgit_filter *source_filter;
struct cgit_filter *email_filter;
struct cgit_filter *auth_filter;
};
struct cgit_page {
@ -278,6 +279,10 @@ struct cgit_environment {
const char *script_name;
const char *server_name;
const char *server_port;
const char *http_cookie;
const char *http_referer;
unsigned int content_length;
int authenticated;
};
struct cgit_context {

View File

@ -42,6 +42,13 @@ agefile::
hh:mm:ss". You may want to generate this file from a post-receive
hook. Default value: "info/web/last-modified".
auth-filter::
Specifies a command that will be invoked for authenticating repository
access. Receives quite a few arguments, and data on both stdin and
stdout for authentication processing. Details follow later in this
document. If no auth-filter is specified, no authentication is
performed. Default value: none. See also: "FILTER API".
branch-sort::
Flag which, when set to "age", enables date ordering in the branch ref
list, and when set to "name" enables ordering by branch name. Default
@ -605,6 +612,8 @@ specification with the relevant string; available values are:
URL escapes for a path and writes 'str' to the webpage.
'html_url_arg(str)'::
URL escapes for an argument and writes 'str' to the webpage.
'html_include(file)'::
Includes 'file' in webpage.
Parameters are provided to filters as follows.
@ -635,7 +644,32 @@ source filter::
file that is to be filtered is available on standard input and the
filtered contents is expected on standard output.
Also, all filters are handed the following environment variables:
auth filter::
The authentication filter receives 11 parameters:
- filter action, explained below, which specifies which action the
filter is called for
- http cookie
- http method
- http referer
- http path
- http https flag
- cgit repo
- cgit page
- cgit url
When the filter action is "body", this filter must write to output the
HTML for displaying the login form, which POSTs to "/?p=login". When
the filter action is "authenticate-cookie", this filter must validate
the http cookie and return a 0 if it is invalid or 1 if it is invalid,
in the exit code / close function. If the filter action is
"authenticate-post", this filter receives POST'd parameters on
standard input, and should write to output one or more "Set-Cookie"
HTTP headers, each followed by a newline.
Please see `filters/simple-authentication.lua` for a clear example
script that may be modified.
All filters are handed the following environment variables:
- CGIT_REPO_URL (from repo.url)
- CGIT_REPO_NAME (from repo.name)

View File

@ -244,6 +244,11 @@ static int html_url_arg_lua_filter(lua_State *lua_state)
return hook_lua_filter(lua_state, html_url_arg);
}
static int html_include_lua_filter(lua_State *lua_state)
{
return hook_lua_filter(lua_state, (void (*)(const char *))html_include);
}
static void cleanup_lua_filter(struct cgit_filter *base)
{
struct lua_filter *filter = (struct lua_filter *)base;
@ -279,6 +284,8 @@ static int init_lua_filter(struct lua_filter *filter)
lua_setglobal(filter->lua_state, "html_url_path");
lua_pushcfunction(filter->lua_state, html_url_arg_lua_filter);
lua_setglobal(filter->lua_state, "html_url_arg");
lua_pushcfunction(filter->lua_state, html_include_lua_filter);
lua_setglobal(filter->lua_state, "html_include");
if (luaL_dofile(filter->lua_state, filter->script_file)) {
error_lua_filter(filter);
@ -409,6 +416,10 @@ struct cgit_filter *cgit_new_filter(const char *cmd, filter_type filtertype)
colon = NULL;
switch (filtertype) {
case AUTH:
argument_count = 11;
break;
case EMAIL:
argument_count = 2;
break;

View File

@ -0,0 +1,225 @@
-- This script may be used with the auth-filter. Be sure to configure it as you wish.
--
-- Requirements:
-- luacrypto >= 0.3
-- <http://mkottman.github.io/luacrypto/>
--
--
--
-- Configure these variables for your settings.
--
--
local protected_repos = {
glouglou = { laurent = true, jason = true },
qt = { jason = true, bob = true }
}
local users = {
jason = "secretpassword",
laurent = "s3cr3t",
bob = "ilikelua"
}
local secret = "BE SURE TO CUSTOMIZE THIS STRING TO SOMETHING BIG AND RANDOM"
--
--
-- Authentication functions follow below. Swap these out if you want different authentication semantics.
--
--
-- Sets HTTP cookie headers based on post
function authenticate_post()
local password = users[post["username"]]
-- TODO: Implement time invariant string comparison function to mitigate against timing attack.
if password == nil or password ~= post["password"] then
construct_cookie("", "cgitauth")
else
construct_cookie(post["username"], "cgitauth")
end
return 0
end
-- Returns 1 if the cookie is valid and 0 if it is not.
function authenticate_cookie()
accepted_users = protected_repos[cgit["repo"]]
if accepted_users == nil then
-- We return as valid if the repo is not protected.
return 1
end
local username = validate_cookie(get_cookie(http["cookie"], "cgitauth"))
if username == nil or not accepted_users[username] then
return 0
else
return 1
end
end
-- Prints the html for the login form.
function body()
html("<h2>Authentication Required</h2>")
html("<form method='post' action='")
html_attr(cgit["login"])
html("'>")
html("<table>")
html("<tr><td><label for='username'>Username:</label></td><td><input id='username' name='username' autofocus /></td></tr>")
html("<tr><td><label for='password'>Password:</label></td><td><input id='password' name='password' type='password' /></td></tr>")
html("<tr><td colspan='2'><input value='Login' type='submit' /></td></tr>")
html("</table></form>")
return 0
end
--
--
-- Cookie construction and validation helpers.
--
--
local crypto = require("crypto")
-- Returns username of cookie if cookie is valid. Otherwise returns nil.
function validate_cookie(cookie)
local i = 0
local username = ""
local expiration = 0
local salt = ""
local hmac = ""
if cookie:len() < 3 or cookie:sub(1, 1) == "|" then
return nil
end
for component in string.gmatch(cookie, "[^|]+") do
if i == 0 then
username = component
elseif i == 1 then
expiration = tonumber(component)
if expiration == nil then
expiration = 0
end
elseif i == 2 then
salt = component
elseif i == 3 then
hmac = component
else
break
end
i = i + 1
end
if hmac == nil or hmac:len() == 0 then
return nil
end
-- TODO: implement time invariant comparison to prevent against timing attack.
if hmac ~= crypto.hmac.digest("sha1", username .. "|" .. tostring(expiration) .. "|" .. salt, secret) then
return nil
end
if expiration <= os.time() then
return nil
end
return username:lower()
end
function construct_cookie(username, cookie)
local authstr = ""
if username:len() > 0 then
-- One week expiration time
local expiration = os.time() + 604800
local salt = crypto.hex(crypto.rand.bytes(16))
authstr = username .. "|" .. tostring(expiration) .. "|" .. salt
authstr = authstr .. "|" .. crypto.hmac.digest("sha1", authstr, secret)
end
html("Set-Cookie: " .. cookie .. "=" .. authstr .. "; HttpOnly")
if http["https"] == "yes" or http["https"] == "on" or http["https"] == "1" then
html("; secure")
end
html("\n")
end
--
--
-- Wrapper around filter API follows below, exposing the http table, the cgit table, and the post table to the above functions.
--
--
local actions = {}
actions["authenticate-post"] = authenticate_post
actions["authenticate-cookie"] = authenticate_cookie
actions["body"] = body
function filter_open(...)
action = actions[select(1, ...)]
http = {}
http["cookie"] = select(2, ...)
http["method"] = select(3, ...)
http["query"] = select(4, ...)
http["referer"] = select(5, ...)
http["path"] = select(6, ...)
http["host"] = select(7, ...)
http["https"] = select(8, ...)
cgit = {}
cgit["repo"] = select(9, ...)
cgit["page"] = select(10, ...)
cgit["url"] = select(11, ...)
cgit["login"] = ""
for _ in cgit["url"]:gfind("/") do
cgit["login"] = cgit["login"] .. "../"
end
cgit["login"] = cgit["login"] .. "?p=login"
end
function filter_close()
return action()
end
function filter_write(str)
post = parse_qs(str)
end
--
--
-- Utility functions follow below, based on keplerproject/wsapi.
--
--
function url_decode(str)
if not str then
return ""
end
str = string.gsub(str, "+", " ")
str = string.gsub(str, "%%(%x%x)", function(h) return string.char(tonumber(h, 16)) end)
str = string.gsub(str, "\r\n", "\n")
return str
end
function parse_qs(qs)
local tab = {}
for key, val in string.gmatch(qs, "([^&=]+)=([^&=]*)&?") do
tab[url_decode(key)] = url_decode(val)
end
return tab
end
function get_cookie(cookies, name)
cookies = string.gsub(";" .. cookies .. ";", "%s*;%s*", ";")
return url_decode(string.match(cookies, ";" .. name .. "=(.-);"))
end

View File

@ -641,6 +641,8 @@ void cgit_print_http_headers(struct cgit_context *ctx)
if (ctx->page.filename)
htmlf("Content-Disposition: inline; filename=\"%s\"\n",
ctx->page.filename);
if (!ctx->env.authenticated)
html("Cache-Control: no-cache, no-store\n");
htmlf("Last-Modified: %s\n", http_date(ctx->page.modified));
htmlf("Expires: %s\n", http_date(ctx->page.expires));
if (ctx->page.etag)
@ -814,14 +816,16 @@ static void print_header(struct cgit_context *ctx)
cgit_index_link("index", NULL, NULL, NULL, NULL, 0);
html(" : ");
cgit_summary_link(ctx->repo->name, ctx->repo->name, NULL, NULL);
html("</td><td class='form'>");
html("<form method='get' action=''>\n");
cgit_add_hidden_formfields(0, 1, ctx->qry.page);
html("<select name='h' onchange='this.form.submit();'>\n");
for_each_branch_ref(print_branch_option, ctx->qry.head);
html("</select> ");
html("<input type='submit' name='' value='switch'/>");
html("</form>");
if (ctx->env.authenticated) {
html("</td><td class='form'>");
html("<form method='get' action=''>\n");
cgit_add_hidden_formfields(0, 1, ctx->qry.page);
html("<select name='h' onchange='this.form.submit();'>\n");
for_each_branch_ref(print_branch_option, ctx->qry.head);
html("</select> ");
html("<input type='submit' name='' value='switch'/>");
html("</form>");
}
} else
html_txt(ctx->cfg.root_title);
html("</td></tr>\n");
@ -843,11 +847,11 @@ static void print_header(struct cgit_context *ctx)
void cgit_print_pageheader(struct cgit_context *ctx)
{
html("<div id='cgit'>");
if (!ctx->cfg.noheader)
if (!ctx->env.authenticated || !ctx->cfg.noheader)
print_header(ctx);
html("<table class='tabs'><tr><td>\n");
if (ctx->repo) {
if (ctx->env.authenticated && ctx->repo) {
cgit_summary_link("summary", NULL, hc(ctx, "summary"),
ctx->qry.head);
cgit_refs_link("refs", NULL, hc(ctx, "refs"), ctx->qry.head,
@ -886,7 +890,7 @@ void cgit_print_pageheader(struct cgit_context *ctx)
html("'/>\n");
html("<input type='submit' value='search'/>\n");
html("</form>\n");
} else {
} else if (ctx->env.authenticated) {
site_link(NULL, "index", NULL, hc(ctx, "repolist"), NULL, NULL, 0);
if (ctx->cfg.root_readme)
site_link("about", "about", NULL, hc(ctx, "about"),
@ -902,7 +906,7 @@ void cgit_print_pageheader(struct cgit_context *ctx)
html("</form>");
}
html("</td></tr></table>\n");
if (ctx->qry.vpath) {
if (ctx->env.authenticated && ctx->qry.vpath) {
html("<div class='path'>");
html("path: ");
cgit_print_path_crumbs(ctx, ctx->qry.vpath);