neocgit

a more 'modern' version of cgit
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commit d6e9200cc35411f3f27426b608bcfdef9348e6d3
parent 3741254a6989b2837cd8d20480f152f0096bcb9a
Author: Jason A. Donenfeld <Jason@zx2c4.com>
Date:   Tue, 14 Jan 2014 21:49:31 +0100

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>

Diffstat:
Mcgit.c | 96+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
Mcgit.h | 7++++++-
Mcgitrc.5.txt | 36+++++++++++++++++++++++++++++++++++-
Mfilter.c | 11+++++++++++
Afilters/simple-authentication.lua | 225+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Mui-shared.c | 28++++++++++++++++------------
6 files changed, 387 insertions(+), 16 deletions(-)

diff --git 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 +599,92 @@ 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); diff --git 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 @@ -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 @@ -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 @@ -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 diff --git a/ui-shared.c b/ui-shared.c @@ -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);