FileWall : Implementing File Access Policies Using Dynamic Access Context Stephen Smaldone, Aniruddha Bohra, and Liviu Iftode DiscoLab Department of Computer Science Rutgers University Workshop on Spontaneous Networking May 12, 2006
Organization: Too many files, directories, servers Protection: Left to the discretion of the owner Dynamism: Cannot be incorporated without file system extension Workshop on Spontaneous Networking
Organization: Too many files, directories, servers Protection: Left to the discretion of the owner Dynamism: Cannot be incorporated without file system extension Administrator has little control over file access policies Administrator has little control over file access policies Workshop on Spontaneous Networking
File names are powerful Can be used to implement access policies All file system access are performed through messages Message transformations can be used to enforce policies File system state can be constructed using information contained in messages Workshop on Spontaneous Networking
File names are powerful Can be used to implement access policies All file system access are performed through messages Message transformations can be used to enforce policies File system state can be constructed using information contained in messages Access policies can be implemented by interposition Access policies can be implemented by interposition and message transformation and message transformation Workshop on Spontaneous Networking
Interposes on the client - server path Stores network flow history Evaluates each message against the firewall policies Passes - through, drops, or transforms network packets Workshop on Spontaneous Networking
Interposes on client - server path Stores file access history Evaluates each message against FileWall policies Transforms file system messages Workshop on Spontaneous Networking
Interposes on client - server path Stores file access history Evaluates each message against FileWall policies Transforms file system messages FileWall constructs virtual namespaces using file FileWall constructs virtual namespaces using file system namespaces and access policies through system namespaces and access policies through message transformation message transformation Workshop on Spontaneous Networking
Access control Quality of Service (QoS) File system organization Intrusion detection Information Lifecycle Management (ILM) Data transformations Workshop on Spontaneous Networking
Motivation Design Access Context FileWall Policies Implementation Evaluation Related Work Conclusions Workshop on Spontaneous Networking
Access history Access statistics Sequence of accesses Describes user behavior Environment Time, available disk space, CPU load, etc. Workshop on Spontaneous Networking
Requirements Compact representation Contain semantic information which describes user behavior Easy to understand and specify Soft state Workshop on Spontaneous Networking
Node = file run Groups of accesses performed by same application Open to close or approximate using clustered accesses Attributes File name Type of run (READ, WRITE, etc.) Operation count Edge Run started after and ended before parent Depth-first traversal defines sequence of runs in an access tree Workshop on Spontaneous Networking
Root Workshop on Spontaneous Networking
Root 1 Read 1 Workshop on Spontaneous Networking
Root 1 2 Read 1, Create/Delete 2 Workshop on Spontaneous Networking
Root 1 3 2 Read 1, Create/Delete 2, Read/Write 3 Workshop on Spontaneous Networking
Root 1 3 1 2 Read 1, Create/Delete 2, Read/Write 3, Write 1 Workshop on Spontaneous Networking
Motivation Design Access Context FileWall Policies Implementation Evaluation Related Work Conclusions Workshop on Spontaneous Networking
Transform messages (requests and replies) Sequence of rules INPUT and OUTPUT Use: Access context File attributes contained in messages Workshop on Spontaneous Networking
Policy: Show files accessed today For each client-visible file: Access Time = TODAY Transform directory listing messages READDIR and READDIRPLUS Workshop on Spontaneous Networking
Policies Access Context FileWall Workshop on Spontaneous Networking
Policies M READDIR Access Context FileWall Workshop on Spontaneous Networking
Policies READDIR Access Context FileWall Workshop on Spontaneous Networking
Policies READDIR Access Context FileWall Workshop on Spontaneous Networking
Policies READDIR READDIRPLUS Access Context FileWall Workshop on Spontaneous Networking
Policies READDIRPLUS Access Context FileWall Workshop on Spontaneous Networking
Policies READDIRPLUS Access Context FileWall Workshop on Spontaneous Networking
Policies READDIRPLUS Access Context FileWall Workshop on Spontaneous Networking
Policies READDIR READDIRPLUS Access Context FileWall Workshop on Spontaneous Networking
OUTPUT Rule: INPUT Rule: int fwout ( rpc _ msg reply) { int fwin ( rpc _ msg request) { if (reply.proc == READDIRPLUS) { if (request.proc == READDIR) { FOREACH entp in reply { request.proc = READDIRPLUS; if (entp . atime == TODAY) return FORWARD; copy_entry( resp _ entp , entp ) } } } reply.entries = res _ entp ; reply.proc = READDIR ; return FORWARD; } } Specified as C programs and compiled as loadable Specified as C programs and compiled as loadable shared modules shared modules Workshop on Spontaneous Networking
Motivation Design Access Context FileWall Policies Implementation Evaluation Related Work Conclusions Workshop on Spontaneous Networking
FileWall: Click Modular Router NFS over UDP Workshop on Spontaneous Networking
FileWall Click Modular Router NFS over UDP FileWall Client SFS toolkit Session establishment Bootstrapping Identify list of available file systems Workshop on Spontaneous Networking
Motivation Design Access Context FileWall Policies Implementation Evaluation Related Work Conclusions Workshop on Spontaneous Networking
Workshop on Spontaneous Networking
General purpose server Email, user homes, web server Files mounted over NFS Web servers are prone to flash crowds Current policies Rate limit number of requests Disable web server Workshop on Spontaneous Networking
Access context Rate of sequential file reads, directory listings, etc. Policy Hide files with rate greater than a threshold Show files again when rate falls below threshold Only the source of the flash crowd disappears from the namespace Workshop on Spontaneous Networking
Workshop on Spontaneous Networking
Infokernel [Arpaci-Dusseau 03], firewall/NAT Access Context Desktop search [ Soules 03] File system prefetching [ Amer 02, Lei 97] Enforcing enterprise -wide policies [He 05] Semantic file systems [Sheldon 91, Pike 93, Neuman 92, Rao 93] Extensible file systems [Zadok 00, Tewari 05] Workshop on Spontaneous Networking
User study Real deployment Behavior models Workshop on Spontaneous Networking
User study Real deployment Behavior models Policy language Constraints Debugging and logging Workshop on Spontaneous Networking
User study Real deployment Behavior models Policy language Constraints Debugging and logging Data transformations Censorship Protocol translations NFS - > CIFS Recipe - based file system (CASPER) IP - > RDMA Video encoding Content adaptation Workshop on Spontaneous Networking
Per-file access policies can be enforced using virtual namespaces No client or server modification required Soft state maintenance required Workshop on Spontaneous Networking
Per-file access policies can be enforced using virtual namespaces No client or server modification required Soft state maintenance required Provides administrators the ability to define a wide variety of access policies Protect file systems Provide quality of service Workshop on Spontaneous Networking
Dell Poweredge 2600 systems Dual 2.4GHz Intel Xeon processors 1GB RAM 36GB 15000 RPM SCSI disk Linux Gigabit Ethernet switch Workshop on Spontaneous Networking
Workshop on Spontaneous Networking
Expressive Deployable Scalable Available Workshop on Spontaneous Networking
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