ctx->qry.url ? ctx->qry.url : "");
}
+/* We intentionally keep this rather small, instead of looping and
+ * feeding it to the filter a couple bytes at a time. This way, the
+ * filter itself does not need to handle any denial of service or
+ * buffer bloat issues. If this winds up being too small, people
+ * will complain on the mailing list, and we'll increase it as needed. */
#define MAX_AUTHENTICATION_POST_BYTES 4096
+/* The filter is expected to spit out "Status: " and all headers. */
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;
+
+ open_auth_filter(ctx, "authenticate-post");
len = ctx->env.content_length;
if (len > MAX_AUTHENTICATION_POST_BYTES)
len = MAX_AUTHENTICATION_POST_BYTES;
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);
}
--
--
--- Sets HTTP cookie headers based on post
+-- Sets HTTP cookie headers based on post and sets up redirection.
function authenticate_post()
local password = users[post["username"]]
- -- TODO: Implement time invariant string comparison function to mitigate against timing attack.
+ local redirect = validate_value(post["redirect"])
+
+ if redirect == nil then
+ not_found()
+ return 0
+ end
+
+ redirect_to(redirect)
+
+ -- TODO: Implement time invariant string comparison function to mitigate timing attack.
if password == nil or password ~= post["password"] then
- construct_cookie("", "cgitauth")
+ set_cookie("cgitauth", "")
else
- construct_cookie(post["username"], "cgitauth")
+ -- One week expiration time
+ local username = secure_value(post["username"], os.time() + 604800)
+ set_cookie("cgitauth", username)
end
+
+ html("\n")
return 0
end
return 1
end
- local username = validate_cookie(get_cookie(http["cookie"], "cgitauth"))
- if username == nil or not accepted_users[username] then
+ local username = validate_value(get_cookie(http["cookie"], "cgitauth"))
+ if username == nil or not accepted_users[username:lower()] then
return 0
else
return 1
html("<form method='post' action='")
html_attr(cgit["login"])
html("'>")
+ html("<input type='hidden' name='redirect' value='")
+ html_attr(secure_value(cgit["url"], 0))
+ 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>")
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.
+-- Wrapper around filter API, exposing the http table, the cgit table, and the post table to the above functions.
--
--
--
--
--- Utility functions follow below, based on keplerproject/wsapi.
+-- Utility functions based on keplerproject/wsapi.
--
--
return str
end
+function url_encode(str)
+ if not str then
+ return ""
+ end
+ str = string.gsub(str, "\n", "\r\n")
+ str = string.gsub(str, "([^%w ])", function (c) return string.format("%%%02X", string.byte(c)) end)
+ str = string.gsub(str, " ", "+")
+ return str
+end
+
function parse_qs(qs)
local tab = {}
for key, val in string.gmatch(qs, "([^&=]+)=([^&=]*)&?") do
cookies = string.gsub(";" .. cookies .. ";", "%s*;%s*", ";")
return url_decode(string.match(cookies, ";" .. name .. "=(.-);"))
end
+
+
+--
+--
+-- Cookie construction and validation helpers.
+--
+--
+
+local crypto = require("crypto")
+
+-- Returns value of cookie if cookie is valid. Otherwise returns nil.
+function validate_value(cookie)
+ local i = 0
+ local value = ""
+ local expiration = 0
+ local salt = ""
+ local hmac = ""
+
+ if cookie == nil or cookie:len() < 3 or cookie:sub(1, 1) == "|" then
+ return nil
+ end
+
+ for component in string.gmatch(cookie, "[^|]+") do
+ if i == 0 then
+ value = 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", value .. "|" .. tostring(expiration) .. "|" .. salt, secret) then
+ return nil
+ end
+
+ if expiration ~= 0 and expiration <= os.time() then
+ return nil
+ end
+
+ return url_decode(value)
+end
+
+function secure_value(value, expiration)
+ if value == nil or value:len() <= 0 then
+ return ""
+ end
+
+ local authstr = ""
+ local salt = crypto.hex(crypto.rand.bytes(16))
+ value = url_encode(value)
+ authstr = value .. "|" .. tostring(expiration) .. "|" .. salt
+ authstr = authstr .. "|" .. crypto.hmac.digest("sha1", authstr, secret)
+ return authstr
+end
+
+function set_cookie(cookie, value)
+ html("Set-Cookie: " .. cookie .. "=" .. value .. "; HttpOnly")
+ if http["https"] == "yes" or http["https"] == "on" or http["https"] == "1" then
+ html("; secure")
+ end
+ html("\n")
+end
+
+function redirect_to(url)
+ html("Status: 302 Redirect\n")
+ html("Cache-Control: no-cache, no-store\n")
+ html("Location: " .. url .. "\n")
+end
+
+function not_found()
+ html("Status: 404 Not Found\n")
+ html("Cache-Control: no-cache, no-store\n\n")
+end
projects / cgit / commitdiff