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authorJason A. Donenfeld <Jason@zx2c4.com>2015-03-05 15:45:25 +0100
committerJason A. Donenfeld <Jason@zx2c4.com>2015-03-05 15:51:22 +0100
commitecd6b7230c88deb23f880ee1df75ae4b230cf9ec (patch)
tree2ac0b03d38e62eb8ee57cb7f7b231a9201e92888 /filters
parentbd24832cd7a72117afb7fa785f4e6bfa4324bf30 (diff)
simple-authentication.lua: tie secure cookies to field names
Diffstat (limited to 'filters')
-rw-r--r--filters/simple-authentication.lua34
1 files changed, 21 insertions, 13 deletions
diff --git a/filters/simple-authentication.lua b/filters/simple-authentication.lua
index cc86b7e..de34d09 100644
--- a/filters/simple-authentication.lua
+++ b/filters/simple-authentication.lua
@@ -46,7 +46,7 @@ local secret = "BE SURE TO CUSTOMIZE THIS STRING TO SOMETHING BIG AND RANDOM"
-- Sets HTTP cookie headers based on post and sets up redirection.
function authenticate_post()
local password = users[post["username"]]
- local redirect = validate_value(post["redirect"])
+ local redirect = validate_value("redirect", post["redirect"])
if redirect == nil then
not_found()
@@ -60,7 +60,7 @@ function authenticate_post()
set_cookie("cgitauth", "")
else
-- One week expiration time
- local username = secure_value(post["username"], os.time() + 604800)
+ local username = secure_value("username", post["username"], os.time() + 604800)
set_cookie("cgitauth", username)
end
@@ -77,7 +77,7 @@ function authenticate_cookie()
return 1
end
- local username = validate_value(get_cookie(http["cookie"], "cgitauth"))
+ local username = validate_value("username", get_cookie(http["cookie"], "cgitauth"))
if username == nil or not accepted_users[username:lower()] then
return 0
else
@@ -92,7 +92,7 @@ function body()
html_attr(cgit["login"])
html("'>")
html("<input type='hidden' name='redirect' value='")
- html_attr(secure_value(cgit["url"], 0))
+ html_attr(secure_value("redirect", cgit["url"], 0))
html("' />")
html("<table>")
html("<tr><td><label for='username'>Username:</label></td><td><input id='username' name='username' autofocus /></td></tr>")
@@ -194,9 +194,10 @@ end
local crypto = require("crypto")
-- Returns value of cookie if cookie is valid. Otherwise returns nil.
-function validate_value(cookie)
+function validate_value(expected_field, cookie)
local i = 0
local value = ""
+ local field = ""
local expiration = 0
local salt = ""
local hmac = ""
@@ -207,15 +208,17 @@ function validate_value(cookie)
for component in string.gmatch(cookie, "[^|]+") do
if i == 0 then
- value = component
+ field = component
elseif i == 1 then
+ value = component
+ elseif i == 2 then
expiration = tonumber(component)
if expiration == nil then
- expiration = 0
+ expiration = -1
end
- elseif i == 2 then
- salt = component
elseif i == 3 then
+ salt = component
+ elseif i == 4 then
hmac = component
else
break
@@ -228,18 +231,22 @@ function validate_value(cookie)
end
-- Lua hashes strings, so these comparisons are time invariant.
- if hmac ~= crypto.hmac.digest("sha1", value .. "|" .. tostring(expiration) .. "|" .. salt, secret) then
+ if hmac ~= crypto.hmac.digest("sha1", field .. "|" .. value .. "|" .. tostring(expiration) .. "|" .. salt, secret) then
+ return nil
+ end
+
+ if expiration == -1 or (expiration ~= 0 and expiration <= os.time()) then
return nil
end
- if expiration ~= 0 and expiration <= os.time() then
+ if url_decode(field) ~= expected_field then
return nil
end
return url_decode(value)
end
-function secure_value(value, expiration)
+function secure_value(field, value, expiration)
if value == nil or value:len() <= 0 then
return ""
end
@@ -247,7 +254,8 @@ function secure_value(value, expiration)
local authstr = ""
local salt = crypto.hex(crypto.rand.bytes(16))
value = url_encode(value)
- authstr = value .. "|" .. tostring(expiration) .. "|" .. salt
+ field = url_encode(field)
+ authstr = field .. "|" .. value .. "|" .. tostring(expiration) .. "|" .. salt
authstr = authstr .. "|" .. crypto.hmac.digest("sha1", authstr, secret)
return authstr
end