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LdapAdapter: Keep track of already processed groups to account for circular references #38817

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Dec 9, 2021
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LdapAdapter: Keep track of already processed groups to account for circular references #38817

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26 changes: 18 additions & 8 deletions src/Security/Authentication/Negotiate/src/Internal/LdapAdapter.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -68,7 +68,7 @@ public static async Task RetrieveClaimsAsync(LdapSettings settings, ClaimsIdenti

if (!settings.IgnoreNestedGroups)
{
GetNestedGroups(settings.LdapConnection, identity, distinguishedName, groupCN, logger, retrievedClaims);
GetNestedGroups(settings.LdapConnection, identity, distinguishedName, groupCN, logger, retrievedClaims, new HashSet<string>());
}
else
{
Expand Down Expand Up @@ -96,8 +96,10 @@ public static async Task RetrieveClaimsAsync(LdapSettings settings, ClaimsIdenti
}
}

private static void GetNestedGroups(LdapConnection connection, ClaimsIdentity principal, string distinguishedName, string groupCN, ILogger logger, IList<string> retrievedClaims)
private static void GetNestedGroups(LdapConnection connection, ClaimsIdentity principal, string distinguishedName, string groupCN, ILogger logger, IList<string> retrievedClaims, HashSet<string> processedGroups)
{
retrievedClaims.Add(groupCN);

var filter = $"(&(objectClass=group)(sAMAccountName={groupCN}))"; // This is using ldap search query language, it is looking on the server for someUser
var searchRequest = new SearchRequest(distinguishedName, filter, SearchScope.Subtree);
var searchResponse = (SearchResponse)connection.SendRequest(searchRequest);
Expand All @@ -109,18 +111,26 @@ private static void GetNestedGroups(LdapConnection connection, ClaimsIdentity pr
logger.LogWarning($"More than one response received for query: {filter} with distinguished name: {distinguishedName}");
}

var group = searchResponse.Entries[0]; //Get the object that was found on ldap
string name = group.DistinguishedName;
retrievedClaims.Add(name);
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@RoadTrain RoadTrain Dec 3, 2021 •
edited
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In general, we use a group Common Name (CN, like SomeGroup) as a claim name. In this particular instance, a Distinguished Name (DN, like CN=SomeGroup,DC=domain,DC=com) was used instead, which I think is incorrect.
Possibly a typo, was introduced in #25075

var group = searchResponse.Entries[0]; // Get the object that was found on ldap
var groupDN = group.DistinguishedName;

processedGroups.Add(groupDN);

var memberof = group.Attributes["memberof"]; // You can access ldap Attributes with Attributes property
if (memberof != null)
{
foreach (var member in memberof)
{
var groupDN = $"{Encoding.UTF8.GetString((byte[])member)}";
var nestedGroupCN = groupDN.Split(',')[0].Substring("CN=".Length);
GetNestedGroups(connection, principal, distinguishedName, nestedGroupCN, logger, retrievedClaims);
var nestedGroupDN = $"{Encoding.UTF8.GetString((byte[])member)}";
var nestedGroupCN = nestedGroupDN.Split(',')[0].Substring("CN=".Length);

if (processedGroups.Contains(nestedGroupDN))
{
// We need to keep track of already processed groups because circular references are possible with AD groups
return;
}

GetNestedGroups(connection, principal, distinguishedName, nestedGroupCN, logger, retrievedClaims, processedGroups);
}
}
}
Expand Down