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CloudPolice : Taking Access Control Out of the Network. Lucian Popa Minlan Yu Steven Y. Ko UC Berkeley/ICSI Princeton Univ. Princeton Univ. Sylvia Ratnasamy Ion Stoica Intel Labs Berkeley UC Berkeley. Context.
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CloudPolice: Taking Access Control Out of the Network Lucian PopaMinlan Yu Steven Y. KoUC Berkeley/ICSI Princeton Univ. Princeton Univ. Sylvia Ratnasamy Ion StoicaIntel Labs Berkeley UC Berkeley
Context • Infrastructure as a Service virtualized clouds • Traffic internal to cloud VM VM VM Hypervisor
Context • Cloud computing requires network access control
Context • Cloud computing requires network access control • Access control policy of tenant X = what network traffic is tenant X willing to accept Y can talk to me Tenant X Tenant Y
Why Access Control in Clouds? (1) • For isolation • Policy: deny incoming traffic from any other tenant Exbay Amazonia
Why Access Control in Clouds? (2) • For inter-tenant & tenant-provider communication • Policy: allow/deny traffic from specific tenants • Increasingly common in cloud environments • Low latency and high bandwidth • Ease of service composition Exbay Amazonia
Why Access Control in Clouds? (2) • For inter-tenant & tenant-provider communication • Policy: allow/deny traffic from specific tenants Exbay Amazonia Real-time bidding advertising
Why Access Control in Clouds? (2) • For inter-tenant & tenant-provider communication • Policy: allow/deny traffic from specific tenants Send information about client Exbay Amazonia Ad Networks Ad Network 2 Ad Network 1 Real-time bidding advertising
Why Access Control in Clouds? (2) • For inter-tenant & tenant-provider communication • Policy: allow/deny traffic from specific tenants Receive ad bids Exbay Amazonia Ad Networks Ad Network 2 Ad Network 1 Real-time bidding advertising
Why Access Control in Clouds? (2) • For inter-tenant & tenant-provider communication • Policy: allow/deny traffic from specific tenants Return ad of highest bidder Exbay Amazonia Ad Networks Ad Network 2 Ad Network 1 Real-time bidding advertising
Why Access Control in Clouds? (2) • For inter-tenant & tenant-provider communication • Policy: allow/deny traffic from specific tenants Policy of Exbay: allow traffic from AdNetworks, deny all other traffic Exbay Amazonia Ad Networks Ad Network 2 Ad Network 1 Real-time bidding advertising
Why Access Control in Clouds? (2) • For inter-tenant & tenant-provider communication • Policy: allow/deny traffic from specific tenants • Other service examples: database (SimpleDB), desktop, communication (SQS), map-reduce++, Facebook, host managing, locking, etc. Exbay Amazonia Ad Networks Ad Network 2 Ad Network 1
Why Access Control in Clouds? (3) • For inter-tenant & tenant-provider communication • Policy: weighted bandwidth allocation between tenants Exbay Amazonia Ad Networks Ad Network 2 Ad Network 1
Why Access Control in Clouds? (3) • For inter-tenant & tenant-provider communication • Policy: weighted bandwidth allocation between tenants Share bandwidth fairly among tenants regardless of #VM sources Exbay Nextbay Amazonia Ad Networks Ad Network 2 Ad Network 1
Why Access Control in Clouds? (3) • For inter-tenant & tenant-provider communication • Policy: weighted bandwidth allocation between tenants • Other example policies: • Rate-limited access • Allow only locally initiated connections • Nighttime access only Exbay Nextbay Amazonia Ad Networks Ad Network 2 Ad Network 1
Why Access Control in Clouds? (4) • DoS protection • One tenant can attack another tenant • Reduce bandwidth and slow down machines • Attackers more powerful: higher bandwidths • Barrier is lower: pay for attacking hosts (compromise credit cards instead of hosts) Exbay Nextbay AmazoniaX Ad Networks Ad Network 2 Ad Network 1
Hence, the problem • Want access control in clouds that • Is resilient to DoS • Supports rich inter-tenant policies
Hence, the problem • Want access control in clouds that • Is resilient to DoS • Supports rich inter-tenant policies • Scales • 100k servers • 10k tenants
Hence, the problem • Want access control in clouds that • Is resilient to DoS • Supports rich inter-tenant policies • Scales • Tolerates high dynamicity • 100k VMs started per day, more than one per second
Hence, the problem • Want access control in clouds that • Is resilient to DoS • Supports rich inter-tenant policies • Scales • Tolerates high dynamicity • Traditional access control mechanisms not well suited to meeting these requirements
Existing Access Control • Cloud APIs are narrow • On/off • No locally initiated connections, no rate-limiting, no weighted allocation • Mechanisms inherited from enterprises • VLANs • Firewalls
Existing Access Control • Cloud APIs are narrow • On/off • No locally initiated connections, no rate-limiting, no weighted allocation • Mechanisms inherited from enterprises • VLANs • Firewalls • But clouds != enterprises
Clouds != Enterprises • Enterprises are not multi-tenant • FewDoSconcerns between departments • Typically simpler policies • Enterprises don’t have the same dynamicity and scale • 10k tenants vs. 10s departments; 1 VM/s vs. mostly static • Clouds have different network designs • High bisection bandwidths, multiple paths, different L2/L3 mix • Many new topologies: FatTree, VL2, BCube, DCell, etc.
VLANS not well suited for clouds • Inflexible policies • Difficult to scale (cloud size & dynamicity) • Limited number, spanning tree • Limited network designs • No L3 networks, no multiple paths, inter-VLAN through router
Firewalls not well suited for Clouds • Offering DoS protection is difficult • Must be applied at source hard to update • Inflexible policies • Scale through prefix aggregation • Difficult to manage • 10k tenants with multiple prefixes, different scaling requirements • No L3 networks
Recap • Traditional access control is not well suited for clouds • Couple access control with network operation • With switching – VLANs • With address assignment – Firewalls
Recap • Traditional access control is not well suited for clouds • Couple access control with network operation • With switching – VLANs • With address assignment – Firewalls • CloudPolice takes access control out of the network
Outline • Part 1 – Context and Motivation • Access control for clouds: why and what? • Limitations of traditional mechanisms • Part 2 – CloudPolice • Approach • Operation Cloud Police
Goal Network Access Control for Clouds that is: • Independent of network topology and addressing • Scalable (millions hosts, high churn) • Flexible (on/off access, rated access, fair access) • Robust to (internal) DDoS attacks
CloudPolice • Sufficient and advantageous to implement access control only within hypervisors VM VM VM Hypervisor
CloudPolice • Sufficient and advantageous to implement access control only within hypervisors • Trusted • Network independent • Full software programmability flexible • Close to VMs block unwanted traffic before network and help DoS • Easy deployability VM VM VM Hypervisor
CloudPolice • Sufficient and advantageous to implement access control only within hypervisors CloudPolice Policy Model • Group= set of tenant VMs with same access control policy VM VM VM Hypervisor
CloudPolice • Sufficient and advantageous to implement access control only within hypervisors Policy = set of Rules Rule = IF Condition THEN Action CloudPolice Policy Model VM VM VM Hypervisor
CloudPolice • Sufficient and advantageous to implement access control only within hypervisors • Condition = logical expression with predicates based on: • Group of sender • Packet header • Current time • History of traffic CloudPolice Policy Model VM VM VM Hypervisor
CloudPolice • Sufficient and advantageous to implement access control only within hypervisors • Action: • Allow • Block • Rate-limit (token bucket) CloudPolice Policy Model VM VM VM Hypervisor
CloudPolice • Sufficient and advantageous to implement access control only within hypervisors • Action: • Allow • Block • Rate-limit (token bucket) CloudPolice Policy Model VM VM VM flow Applied per source VM Hypervisor source group
CloudPolice • Hypervisor-based VM VM Dst.VM VM VM Src.VM Hypervisor Hypervisor
CloudPolice • Hypervisor-based • Avoid DoS and wasted resources apply policy at source VM VM Dst.VM VM VM Src.VM Hypervisor Hypervisor
CloudPolice • Hypervisor-based • How to apply destination’s policy at the source hypervisor? VM VM Dst.VM VM VM Src.VM Hypervisor Hypervisor
CloudPolice • Hypervisor-based • Centralized policy repository? VM VM Dst.VM VM VM Src.VM Hypervisor Hypervisor
CloudPolice • Hypervisor-based • Centralized policy repository? VM VM Dst.VM VM VM Src.VM Allow? Hypervisor Hypervisor
CloudPolice • Hypervisor-based • Centralized policy repository? • Centralized service requires high availability and throughput • 100k servers and 10 new flows/VM/s 1M decisions/s on average! • Caching can be ineffective (random patterns, malicious pollution) • Centralized service can be a DoStarget VM VM Dst.VM VM VM Src.VM Allow? Hypervisor Hypervisor
CloudPolice • Hypervisor-based • Decentralized VM VM Dst.VM VM VM Src.VM Hypervisor Hypervisor
CloudPolice • Hypervisor-based • Decentralized • Distribute all policies to all hypervisors? VM VM Dst.VM VM VM Src.VM Hypervisor Hypervisor
CloudPolice • Hypervisor-based • Decentralized • Distribute all policies to all hypervisors? VM VM Dst.VM VM VM Src.VM Hypervisor Hypervisor Allow?
CloudPolice • Hypervisor-based • Decentralized • Distribute all policies to all hypervisors? • Too heavyweight if network independent • Full group membership required; Group updates propagated everywhere • 100k new VMs/day, 100k servers 100k updates/s on average VM VM Dst.VM VM VM Src.VM Hypervisor Hypervisor
CloudPolice • Hypervisor-based • Decentralized • Apply at destination and enforce at source VM VM Dst.VM VM VM Src.VM Apply destination’s policy Hypervisor Hypervisor
CloudPolice • Hypervisor-based • Decentralized • Apply at destination and enforce at source VM VM Dst.VM VM VM Src.VM Enforce policy’s action Hypervisor Hypervisor
Inspired by Internet Research • Internet solutions to DDoS • Push-back filters [AIP, Pushback, AITF, StopIt] • Network Capabilities [SIFF, TVA] • Handle large and dynamic networks, millions of users
Inspired by Internet Research • Internet solutions to DDoS • Push-back filters [AIP, Pushback, AITF, StopIt] • Network Capabilities [SIFF, TVA] • Handle large and dynamic networks, millions of users • More easily deployed: Clouds != Internet • Clouds are controlled environments • Both communication endpoints can be controlled • Single administrative domain • New tools: trusted software layer – Hypervisor