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authorJason A. Donenfeld <Jason@zx2c4.com>2018-07-15 03:22:12 +0200
committerJason A. Donenfeld <Jason@zx2c4.com>2018-07-15 03:30:57 +0200
commitb73df8098f261ecbd4bc5ba689f9766a1a75f9a0 (patch)
treeaebcaab97994951531547194cf9f51ba353dd4ad
parentc4d23d02ec5a26d09d389dcf7b8928ecd5798ccc (diff)
downloadcgit-b73df8098f261ecbd4bc5ba689f9766a1a75f9a0.tar.gz
cgit-b73df8098f261ecbd4bc5ba689f9766a1a75f9a0.tar.xz
auth-filters: generate secret securely
This is much better than having the user generate it themselves. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
-rw-r--r--filters/gentoo-ldap-authentication.lua53
-rw-r--r--filters/simple-authentication.lua50
2 files changed, 85 insertions, 18 deletions
diff --git a/filters/gentoo-ldap-authentication.lua b/filters/gentoo-ldap-authentication.lua
index 3b6564b..b4d98c2 100644
--- a/filters/gentoo-ldap-authentication.lua
+++ b/filters/gentoo-ldap-authentication.lua
@@ -5,7 +5,13 @@
-- <http://mkottman.github.io/luacrypto/>
-- lualdap >= 1.2
-- <https://git.zx2c4.com/lualdap/about/>
+-- luaposix
+-- <https://github.com/luaposix/luaposix>
--
+local sysstat = require("posix.sys.stat")
+local unistd = require("posix.unistd")
+local crypto = require("crypto")
+local lualdap = require("lualdap")
--
@@ -21,11 +27,9 @@ local protected_repos = {
portage = "dev"
}
-
--- All cookies will be authenticated based on this secret. Make it something
--- totally random and impossible to guess. It should be large.
-local secret = "BE SURE TO CUSTOMIZE THIS STRING TO SOMETHING BIG AND RANDOM"
-
+-- Set this to a path this script can write to for storing a persistent
+-- cookie secret, which should be guarded.
+local secret_filename = "/var/cache/cgit/auth-secret"
--
@@ -102,8 +106,6 @@ end
--
--
-local lualdap = require("lualdap")
-
function gentoo_ldap_user_groups(username, password)
-- Ensure the user is alphanumeric
if username == nil or username:match("%W") then
@@ -231,7 +233,38 @@ end
--
--
-local crypto = require("crypto")
+local secret = nil
+
+-- Loads a secret from a file, creates a secret, or returns one from memory.
+function get_secret()
+ if secret ~= nil then
+ return secret
+ end
+ local secret_file = io.open(secret_filename, "r")
+ if secret_file == nil then
+ local old_umask = sysstat.umask(63)
+ local temporary_filename = secret_filename .. ".tmp." .. crypto.hex(crypto.rand.bytes(16))
+ local temporary_file = io.open(temporary_filename, "w")
+ if temporary_file == nil then
+ os.exit(177)
+ end
+ temporary_file:write(crypto.hex(crypto.rand.bytes(32)))
+ temporary_file:close()
+ unistd.link(temporary_filename, secret_filename) -- Intentionally fails in the case that another process is doing the same.
+ unistd.unlink(temporary_filename)
+ sysstat.umask(old_umask)
+ secret_file = io.open(secret_filename, "r")
+ end
+ if secret_file == nil then
+ os.exit(177)
+ end
+ secret = secret_file:read()
+ secret_file:close()
+ if secret:len() ~= 64 then
+ os.exit(177)
+ end
+ return secret
+end
-- Returns value of cookie if cookie is valid. Otherwise returns nil.
function validate_value(expected_field, cookie)
@@ -271,7 +304,7 @@ function validate_value(expected_field, cookie)
end
-- Lua hashes strings, so these comparisons are time invariant.
- if hmac ~= crypto.hmac.digest("sha256", field .. "|" .. value .. "|" .. tostring(expiration) .. "|" .. salt, secret) then
+ if hmac ~= crypto.hmac.digest("sha256", field .. "|" .. value .. "|" .. tostring(expiration) .. "|" .. salt, get_secret()) then
return nil
end
@@ -296,7 +329,7 @@ function secure_value(field, value, expiration)
value = url_encode(value)
field = url_encode(field)
authstr = field .. "|" .. value .. "|" .. tostring(expiration) .. "|" .. salt
- authstr = authstr .. "|" .. crypto.hmac.digest("sha256", authstr, secret)
+ authstr = authstr .. "|" .. crypto.hmac.digest("sha256", authstr, get_secret())
return authstr
end
diff --git a/filters/simple-authentication.lua b/filters/simple-authentication.lua
index 596c041..bf35632 100644
--- a/filters/simple-authentication.lua
+++ b/filters/simple-authentication.lua
@@ -3,7 +3,12 @@
-- Requirements:
-- luacrypto >= 0.3
-- <http://mkottman.github.io/luacrypto/>
+-- luaposix
+-- <https://github.com/luaposix/luaposix>
--
+local sysstat = require("posix.sys.stat")
+local unistd = require("posix.unistd")
+local crypto = require("crypto")
--
@@ -31,11 +36,9 @@ local users = {
bob = "ilikelua"
}
--- All cookies will be authenticated based on this secret. Make it something
--- totally random and impossible to guess. It should be large.
-local secret = "BE SURE TO CUSTOMIZE THIS STRING TO SOMETHING BIG AND RANDOM"
-
-
+-- Set this to a path this script can write to for storing a persistent
+-- cookie secret, which should be guarded.
+local secret_filename = "/var/cache/cgit/auth-secret"
--
--
@@ -191,7 +194,38 @@ end
--
--
-local crypto = require("crypto")
+local secret = nil
+
+-- Loads a secret from a file, creates a secret, or returns one from memory.
+function get_secret()
+ if secret ~= nil then
+ return secret
+ end
+ local secret_file = io.open(secret_filename, "r")
+ if secret_file == nil then
+ local old_umask = sysstat.umask(63)
+ local temporary_filename = secret_filename .. ".tmp." .. crypto.hex(crypto.rand.bytes(16))
+ local temporary_file = io.open(temporary_filename, "w")
+ if temporary_file == nil then
+ os.exit(177)
+ end
+ temporary_file:write(crypto.hex(crypto.rand.bytes(32)))
+ temporary_file:close()
+ unistd.link(temporary_filename, secret_filename) -- Intentionally fails in the case that another process is doing the same.
+ unistd.unlink(temporary_filename)
+ sysstat.umask(old_umask)
+ secret_file = io.open(secret_filename, "r")
+ end
+ if secret_file == nil then
+ os.exit(177)
+ end
+ secret = secret_file:read()
+ secret_file:close()
+ if secret:len() ~= 64 then
+ os.exit(177)
+ end
+ return secret
+end
-- Returns value of cookie if cookie is valid. Otherwise returns nil.
function validate_value(expected_field, cookie)
@@ -231,7 +265,7 @@ function validate_value(expected_field, cookie)
end
-- Lua hashes strings, so these comparisons are time invariant.
- if hmac ~= crypto.hmac.digest("sha256", field .. "|" .. value .. "|" .. tostring(expiration) .. "|" .. salt, secret) then
+ if hmac ~= crypto.hmac.digest("sha256", field .. "|" .. value .. "|" .. tostring(expiration) .. "|" .. salt, get_secret()) then
return nil
end
@@ -256,7 +290,7 @@ function secure_value(field, value, expiration)
value = url_encode(value)
field = url_encode(field)
authstr = field .. "|" .. value .. "|" .. tostring(expiration) .. "|" .. salt
- authstr = authstr .. "|" .. crypto.hmac.digest("sha256", authstr, secret)
+ authstr = authstr .. "|" .. crypto.hmac.digest("sha256", authstr, get_secret())
return authstr
end