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Posted to users@httpd.apache.org by Adam Cécile <ac...@le-vert.net> on 2024/01/25 18:13:01 UTC
[users@httpd] If statement against AUTHENTICATE_memberOf variable created by authnz_ldap
Hello,
I'm struggling with authnz_ldap configuration. What I'm trying to
achieve is the following:
1. Authentication is done against Active Directory
2. Groups of user (memberOf) are retreived and X-PCC-Profile header is
set depending on groups:
- If ADMIN is listed in groups, profile is set to admin
- If OPERATOR is listed in groups, profile is set to operator
- If VIEWER is listed in groups, profile is set to viewer
- If none of the above group is found, X-PCC-Profile header is not set
I came up with a configuration that works, but is ugly (imho) and I have
to perform some fuzzy regex matching and I do not understand why, so I'm
requesting your advice.
Configuration is the following:
Require ldap-group CN=ALLOWED,OU=Groups,DC=domain,DC=internal
RequestHeader add X-PCC-User "%{AUTHENTICATE_sAMAccountName}e"
# For debugging purpose, dump AUTHENTICATE_memberOf variable to unused
X-PCC-Groups header
RequestHeader add X-PCC-Groups "%{AUTHENTICATE_memberOf}e"
RewriteEngine on
RewriteCond %{ENV:AUTHENTICATE_memberOf} "(^|;
)CN=VIEWER,OU=Groups,DC=domain,DC=internal" [NC]
RewriteRule ".*" - [E=PCC_PROFILE:viewer,NE,NS]
RewriteCond %{ENV:AUTHENTICATE_memberOf} "(^|;
)CN=OPERATOR,OU=Groups,DC=domain,DC=internal" [NC]
RewriteRule ".*" - [E=PCC_PROFILE:operator,NE,NS]
RewriteCond %{ENV:AUTHENTICATE_memberOf} "(^|;
)CN=VIEWER,OU=Groups,DC=domain,DC=internal" [NC]
RewriteRule ".*" - [E=PCC_PROFILE:admin,NE,NS]
RequestHeader add X-PCC-Profile "%{PCC_PROFILE}e" "expr=-n
%{ENV:PCC_PROFILE}"
For the record, here is how the debugging X-PCC-Groups header is seen by
next "hop" (in this POC, apache is proxy-passing to NGINX which is
configured to log all headers):
2024/01/25 17:46:14 [debug] 10006#10006: *147 http header:
"X-PCC-Groups: CN=ANOTHERGROUP,OU=Groups,DC=domain,DC=internal;
CN=ALLOWED,OU=Groups,DC=domain,DC=internal;
CN=VIEWER,OU=Groups,DC=domain,DC=internal"
So the first question is: Is it normal that I have to use mod_rewrite to
check for group membership ? I tried hundred of syntaxes with SetEnvIf
or SetEnvIfExpr but I never managed to get it working. I'm not sure why
but I guess it's somehow related to "race condition" (lazy evaluation)
while evaluating environment variable, does it makes sense ?
Second question is: I cannot use "$" to make a proper regex matcher. If
the group is not the last one, I can match it with ;.*$, if it is the
last one, I should be able to match [...]DC=internal$, however that does
not work. There's is one unknown character and I have no idea what it
is. Matching with DC=internal.?$ works, so that's one SINGLE char... Any
idea ?
Thanks in advance,
Best regards, Adam.
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Re: [users@httpd] If statement against AUTHENTICATE_memberOf variable created by authnz_ldap
Posted by Adam Cecile <ac...@le-vert.net>.
On 1/26/24 18:13, Eric Covener wrote:
>> So the first question is: Is it normal that I have to use mod_rewrite to
>> check for group membership ? I tried hundred of syntaxes with SetEnvIf
>> or SetEnvIfExpr but I never managed to get it working. I'm not sure why
>> but I guess it's somehow related to "race condition" (lazy evaluation)
>> while evaluating environment variable, does it makes sense ?
> SetEnvIf[expr] is evaluated very early, long before authn/authz occurs
> and those environment variables can be filled out.
>
>> Second question is: I cannot use "$" to make a proper regex matcher. If
>> the group is not the last one, I can match it with ;.*$, if it is the
>> last one, I should be able to match [...]DC=internal$, however that does
>> not work. There's is one unknown character and I have no idea what it
>> is. Matching with DC=internal.?$ works, so that's one SINGLE char... Any
>> idea ?
>>
Hello,
Thanks a lot for your help. I ended up going for a completely different
way because I found it was too messy... So here is the LUA script I use
instead:
require 'apache2'
local admin_profiles = {
'CN=Group1,OU=Groups,DC=domain,DC=com',
'CG=Group2,DC=domain,DC=com',
}
local manager_profiles = {
'CN=Group1,OU=Groups,DC=domain,DC=com',
'CN=Group3,OU=Groups,DC=domain,DC=com',
}
local operator_profiles = {
}
local viewer_profiles = {
'CN=Group4,OU=Groups,DC=domain,DC=com',
'CN=Group5,OU=Groups,DC=domain,DC=com',
}
local function has_value_case_insensitive(tab, val)
for index, value in ipairs(tab) do
if value:lower() == val:lower() then
return true
end
end
return false
end
function authcheck_hook(r)
-- Extract username and group list from Active Directory authentication
local sam_account_name = r.subprocess_env['AUTHENTICATE_SAMACCOUNTNAME']
local member_of = r.subprocess_env['AUTHENTICATE_MEMBEROF']
-- Check if Active Directory variables are not set, if so, return 403
and log error
if (sam_account_name == nil or sam_account_name == '') then
r:err("ActiveDirectory group to PCC profile LUA script called but
AUTHENTICATE_SAMACCOUNTNAME was not set")
return 403
end
if (member_of == nil or member_of == '') then
r:err("ActiveDirectory group to PCC profile LUA script called but
AUTHENTICATE_MEMBEROF was not set")
return 403
end
-- Split group member ship into an array and match corresponding profile
local member_of_split_regex = '([^;%s*]+)'
local member_of_profiles = {}
for member_of_entry in member_of:gmatch(member_of_split_regex) do
local member_of_entry_profiles = {}
if has_value_case_insensitive(admin_profiles, member_of_entry) then
if not has_value_case_insensitive(member_of_entry_profiles,
"admin") then
table.insert(member_of_entry_profiles, "admin")
end
if not has_value_case_insensitive(member_of_profiles, "admin") then
table.insert(member_of_profiles, "admin")
end
end
if has_value_case_insensitive(manager_profiles, member_of_entry) then
if not has_value_case_insensitive(member_of_entry_profiles,
"manager") then
table.insert(member_of_entry_profiles, "manager")
end
if not has_value_case_insensitive(member_of_profiles, "manager") then
table.insert(member_of_profiles, "manager")
end
end
if has_value_case_insensitive(operator_profiles, member_of_entry) then
if not has_value_case_insensitive(member_of_entry_profiles,
"operator") then
table.insert(member_of_entry_profiles, "operator")
end
if not has_value_case_insensitive(member_of_profiles, "operator")
then
table.insert(member_of_profiles, "operator")
end
end
if has_value_case_insensitive(viewer_profiles, member_of_entry) then
if not has_value_case_insensitive(member_of_entry_profiles,
"viewer") then
table.insert(member_of_entry_profiles, "viewer")
end
if not has_value_case_insensitive(member_of_profiles, "viewer") then
table.insert(member_of_profiles, "viewer")
end
end
if next(member_of_entry_profiles) == nil then
r:debug(("Username %s ActiveDirectory group %s gives no PCC
privileges"):format(sam_account_name, member_of_entry))
else
r:debug(("Username %s ActiveDirectory group %s gives PCC
privileges: %s"):format(sam_account_name, member_of_entry,
table.concat(member_of_entry_profiles, ', ')))
end
end
-- Compare all matched group resulting profile and get the one with
highest privileges
if has_value_case_insensitive(member_of_profiles, "admin") then
r:info(("Username %s authorized with PCC admin
privileges"):format(sam_account_name, member_of_entry))
r.headers_in['X-PCC-Group'] = "admin"
elseif has_value_case_insensitive(member_of_profiles, "manager") then
r:info(("Username %s authorized with PCC manager
privileges"):format(sam_account_name, member_of_entry))
r.headers_in['X-PCC-Group'] = "manager"
elseif has_value_case_insensitive(member_of_profiles, "operator") then
r:err(("Username %s authorized with PCC operator
privileges"):format(sam_account_name, member_of_entry))
r.headers_in['X-PCC-Group'] = "operator"
elseif has_value_case_insensitive(member_of_profiles, "viewer") then
r:err(("Username %s authorized with PCC viewer
privileges"):format(sam_account_name, member_of_entry))
r.headers_in['X-PCC-Group'] = "viewer"
else
r:err(("Username %s ActiveDirectory groups did not give ANY PCC
privileges, it should have NOT been authorized to
login"):format(sam_account_name))
return 403
end
return apache2.OK
end
Which is called from config using:
LuaHookFixups /etc/apache2/snippets/active_directory_to_pcc_profile.lua
authcheck_hook
It seems to be working as expected, and is also working with my
auth_form / cookie_session setup, which is great !
Any comment is welcome is you see something borked...
Regards, Adam.
Re: [users@httpd] If statement against AUTHENTICATE_memberOf variable created by authnz_ldap
Posted by Eric Covener <co...@gmail.com>.
> So the first question is: Is it normal that I have to use mod_rewrite to
> check for group membership ? I tried hundred of syntaxes with SetEnvIf
> or SetEnvIfExpr but I never managed to get it working. I'm not sure why
> but I guess it's somehow related to "race condition" (lazy evaluation)
> while evaluating environment variable, does it makes sense ?
SetEnvIf[expr] is evaluated very early, long before authn/authz occurs
and those environment variables can be filled out.
>
> Second question is: I cannot use "$" to make a proper regex matcher. If
> the group is not the last one, I can match it with ;.*$, if it is the
> last one, I should be able to match [...]DC=internal$, however that does
> not work. There's is one unknown character and I have no idea what it
> is. Matching with DC=internal.?$ works, so that's one SINGLE char... Any
> idea ?
>
You could send it out as a response header for debugging, or maybe
observe it with rewrite:trace8 in the error_log
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