[PATCH] auth: add basic authentication filter framework
Jason A. Donenfeld
Jason at zx2c4.com
Wed Jan 15 19:11:11 CET 2014
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 at zx2c4.com>
---
You can try this out at http://git.zx2c4.com/glouglou/log using
the username "jason" and the password "secretpassword".
cgit.c | 94 +++++++++++++++-
cgit.h | 7 +-
cgitrc.5.txt | 36 +++++-
filter.c | 11 ++
filters/simple-authentication.lua | 225 ++++++++++++++++++++++++++++++++++++++
ui-shared.c | 26 +++--
6 files changed, 383 insertions(+), 16 deletions(-)
create mode 100644 filters/simple-authentication.lua
diff --git a/cgit.c b/cgit.c
index f3fe56b..3e6f0b1 100644
--- a/cgit.c
+++ b/cgit.c
@@ -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 +599,90 @@ 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");
+ htmlf("Location: %s\n", ctx->env.http_referer);
+ } else {
+ html("Status: 503 Invalid Request\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 +996,7 @@ 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 +1034,22 @@ 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);
diff --git a/cgit.h b/cgit.h
index e200a06..496d0f6 100644
--- a/cgit.h
+++ b/cgit.h
@@ -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 {
diff --git a/cgitrc.5.txt b/cgitrc.5.txt
index 170e825..c45dbd3 100644
--- a/cgitrc.5.txt
+++ b/cgitrc.5.txt
@@ -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)
diff --git a/filter.c b/filter.c
index 0cce7bb..a5e5e4b 100644
--- a/filter.c
+++ b/filter.c
@@ -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;
diff --git a/filters/simple-authentication.lua b/filters/simple-authentication.lua
new file mode 100644
index 0000000..6cfd425
--- /dev/null
+++ b/filters/simple-authentication.lua
@@ -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 differen 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("")
+ else
+ construct_cookie(post["username"])
+ 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)
+ 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: cgitauth=" .. 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
diff --git a/ui-shared.c b/ui-shared.c
index abe15cd..598db3a 100644
--- a/ui-shared.c
+++ b/ui-shared.c
@@ -814,14 +814,16 @@ 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 +845,11 @@ 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 +888,7 @@ 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 +904,7 @@ 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);
--
1.8.5.2
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