pwrite卡巴斯基授权文件
卡巴斯基授权文件 时间:2021-02-28 阅读:()
AllFileSystemsAreNotCreatedEqual:OntheComplexityofCraftingCrash-ConsistentApplicationsThanumalayanSankaranarayanaPillai,VijayChidambaram,RamnatthanAlagappan,SamerAl-Kiswany,AndreaC.
Arpaci-Dusseau,RemziH.
Arpaci-DusseauAllFileSystemsAreNotCreatedEqual:OntheComplexityofCraftingCrash-ConsistentApplicationsThanumalayanSankaranarayanaPillai,VijayChidambaram,RamnatthanAlagappan,SamerAl-Kiswany,AndreaC.
Arpaci-Dusseau,RemziH.
Arpaci-DusseauCrashConsistencyMaintainingdatainvariantsacrossasystemcrash‐Example:DatabasetransactionsshouldbeatomicCrashConsistencyMaintainingdatainvariantsacrossasystemcrash‐Example:DatabasetransactionsshouldbeatomicImportantinsystems‐FileSystems‐RelationalDatabases‐Key-ValueStoresCrashConsistencyMaintainingdatainvariantsacrossasystemcrash‐Example:DatabasetransactionsshouldbeatomicImportantinsystems‐FileSystems‐RelationalDatabases‐Key-ValueStoresHardtogetright:ARIESinventedonlyin1992‐ProvingARIEStook5moreyears(1997)Lotsofworkinfilesystemcrashconsistency‐Journaling,copy-on-write,softupdates.
.
.
File-SystemCrashConsistencyLotsofworkinfilesystemcrashconsistency‐Journaling,copy-on-write,softupdates.
.
.
FSconsistencyfocusesoninternalmetadata‐DodirectoriesonlycontainvaliddirectoryentriesFile-SystemCrashConsistencyLotsofworkinfilesystemcrashconsistency‐Journaling,copy-on-write,softupdates.
.
.
FSconsistencyfocusesoninternalmetadata‐DodirectoriesonlycontainvaliddirectoryentriesWhataboutuser-leveldataFile-SystemCrashConsistencyWhatguaranteesdofilesystemsgiveapplications‐Thatcanbeusedforconsistencyofuser-leveldataThisworkstudies.
.
.
Whatguaranteesdofilesystemsgiveapplications‐Thatcanbeusedforconsistencyofuser-leveldataDoapplicationsmaintainconsistencycorrectly‐Importantapplicationsrequireuser-levelconsistency‐Databases,key-valuestores,distributedsystems.
.
.
Thisworkstudies.
.
.
Filesystemguaranteesvarywidely‐Studied16configsofext2,ext3,ext4,btrfs,xfs,reiserfs‐Guaranteesvaryamongconfigsofsamefilesystem‐Guaranteesoftenside-effectsofFSimplementation‐POSIXstandardsofguarantees,ifany,aredebatedWefind.
.
.
Filesystemguaranteesvarywidely‐Studied16configsofext2,ext3,ext4,btrfs,xfs,reiserfs‐Guaranteesvaryamongconfigsofsamefilesystem‐Guaranteesoftenside-effectsofFSimplementation‐POSIXstandardsofguarantees,ifany,aredebatedApplicationsdependonguaranteesinsubtleways‐Studied11applications:Databases,Distributedsystems,Virtualizationsoftware,Key-valuestores,VCS‐60vulnerabilitiesunderaweakfilesystemmodel‐Morethan30vulnerabilitiesunderext3,ext4,btrfsWefind.
.
.
IntroductionAnExampleBOB:ExaminingFileSystemBehaviorALICE:ExaminingApplicationsConclusionOutlineIntroductionAnExampleBOB:ExaminingFileSystemBehaviorALICE:ExaminingApplicationsConclusionOutlineAfileinitiallycontainsthestring"afoo"‐Assumeeachcharacterin"afoo"isablockofdataTask:Atomicallychangethecontentsto"abar"‐Onapowerloss,wemustretrieveeither"afoo"or"abar"ToyExample:OverviewToyExample:SimpleOverwriteInitialstate/x/f1"afoo"Finalstate/x/f1"abar"Modificationpwrite(/x/f1,2,"bar")IntermediatestatespossibleoncrashToyExample:SimpleOverwriteInitialstate/x/f1"afoo"Modificationpwrite(/x/f1,2,"bar")Finalstate/x/f1"abar"Intermediatestate1/x/f1"aboo"Intermediatestate2/x/f1"afar"Intermediatestates3,4,5.
.
.
.
WhatifcrashatomicityisneededUseapplication-levellogging(a.
k.
a.
undologging/rollbackjournaling)a.
Makeacopyofolddatain"log"fileb.
Modifyactualfilec.
Deletelogfiled.
Onacrash,datacanberecoveredfromthelogToyExample:MaintainingConsistencyWhatifcrashatomicityisneededUpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,foo");pwrite(/x/f1,2,"bar");unlink(/x/log1);WritetologActualmodificationDeletelogToyExample:Protocol#1Worksinext3(data-journal)!
UpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,foo");pwrite(/x/f1,2,"bar");unlink(/x/log1);ToyExample:Protocol#1Somepossibleintermediatestates/x/f1"afoo"/x/log1""/x/f1"afoo"/x/log1"2,3,f"/x/f1"aboo"/x/log1"2,3,foo"1.
2.
3.
Worksinext3(data-journal)!
UpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,foo");pwrite(/x/f1,2,"bar");unlink(/x/log1);Somepossibleintermediatestates/x/f1"afoo"/x/log1""/x/f1"afoo"/x/log1"2,3,f"/x/f1"aboo"/x/log1"2,3,foo"1.
2.
3.
ToyExample:Protocol#1SimplydeletelogfileduringrecoveryWorksinext3(data-journal)!
UpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,foo");pwrite(/x/f1,2,"bar");unlink(/x/log1);Somepossibleintermediatestates/x/f1"afoo"/x/log1""/x/f1"afoo"/x/log1"2,3,f"/x/f1"aboo"/x/log1"2,3,foo"1.
2.
3.
ToyExample:Protocol#1RecoverfromlogfileduringrecoveryWorksinext3(data-journal)!
Doesn'tworkinext3(data-ordered)UpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,foo");pwrite(/x/f1,2,"bar");unlink(/x/log1);ToyExample:Protocol#1Worksinext3(data-journal)!
Doesn'tworkinext3(data-ordered)UpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,foo");pwrite(/x/f1,2,"bar");unlink(/x/log1);ext3(ordered)canre-orderthesetworequests,sendingpwrite(f1)todiskfirst,beforewrite(log1)ToyExample:Protocol#1Worksinext3(data-journal)!
Doesn'tworkinext3(data-ordered)UpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,foo");pwrite(/x/f1,2,"bar");unlink(/x/log1);Apossibleintermediatestate/x/f1"aboo"/x/log1""Recoverynotpossible!
ToyExample:Protocol#1Worksinext3(data-journal),(data-ordered)!
UpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,foo");fsync(/x/log1);pwrite(/x/f1,2,"bar");fsync(/x/f1);unlink(/x/log1);ToyExample:Protocol#2Worksinext3(data-journal),(data-ordered)!
Doesn'tworkinext3(writeback)UpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,foo");fsync(/x/log1);pwrite(/x/f1,2,"bar");fsync(/x/f1);unlink(/x/log1);Apossibleintermediatestates/x/f1"afoo"/x/log1"2,3,#!
@"Filesizealoneincreasesforlog1,andgarbageoccurs.
Recoverycannotdifferentiatebetweengarbageanddata!
CrashhereToyExample:Protocol#2Worksinext3(data-journal),(data-ordered),(writeback)UpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,checksum,foo");fsync(/x/log1);pwrite(/x/f1,2,"bar");fsync(/x/f1);unlink(/x/log1);ToyExample:Protocol#3Worksinext3(data-journal),(data-ordered),(writeback)Notenough,accordingtoLinuxmanpagesUpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,checksum,foo");fsync(/x/log1);pwrite(/x/f1,2,"bar");fsync(/x/f1);unlink(/x/log1);Apossibleintermediatestates/x/f1"aboo"Thelogfile'sdirectoryentrymightneverbecreatedToyExample:Protocol#3WorksinallfilesystemsUpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,checksum,foo");fsync(/x/log1);fsync(/x);pwrite(/x/f1,2,"bar");fsync(/x/f1);unlink(/x/log1);ToyExample:Protocol#4Worksinallfilesystems(Additionalfsync()requiredfordurabilityinallFS)UpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,checksum,foo");fsync(/x/log1);fsync(/x);pwrite(/x/f1,2,"bar");fsync(/x/f1);unlink(/x/log1);fsync(/x);ToyExample:Protocol#5Filesystemsvaryincrash-relatedbehavior‐ext3(ordered)re-orders,whileext3(journaled)doesnotApplicationsusuallydependonsomebehavior‐Dependonordering:Somefsync()callscanbeomittedExample:SummaryIntroductionAnExampleBOB:ExaminingFileSystemBehaviorALICE:ExaminingApplicationsConclusionOutlineTwoclassesofproperties:atomicityandordering‐Atomicityexample:Isawrite()callatomicintheFS‐Orderingexample:Arewrite()callssenttodiskin-orderStudiedext2,ext3,ext4,btrfs,xfs,reiserfs‐Westudied16configurationsofthesixfilesystemsFSBehavior:PersistenceProperties1.
Runuser-levelworkloadsstressingtheproperty‐Example:write(8KB)fortestingatomicityofwrite()callsMethodology:TheBlock-OrderBreaker(BOB)1.
Runuser-levelworkloadsstressingtheproperty‐Example:write(8KB)fortestingatomicityofwrite()calls2.
Recordblock-leveltraceoftheworkloadMethodology:TheBlock-OrderBreaker(BOB)1.
Runuser-levelworkloadsstressingtheproperty‐Example:write(8KB)fortestingatomicityofwrite()calls2.
Recordblock-leveltraceoftheworkload3.
Reconstructdisk-statespossibleonapower-loss‐Allstatespossibleifdisk-cachedoesnotre-order‐Afewstateswheredisk-cachere-ordersMethodology:TheBlock-OrderBreaker(BOB)1.
Runuser-levelworkloadsstressingtheproperty‐Example:write(8KB)fortestingatomicityofwrite()calls2.
Recordblock-leveltraceoftheworkload3.
Reconstructdisk-statespossibleonapower-loss‐Allstatespossibleifdisk-cachedoesnotre-order‐Afewstateswheredisk-cachere-orders4.
RunFSrecovery,verifypropertyoneachdisk-state‐Example:Isall8KBwrittenatomicallyMethodology:TheBlock-OrderBreaker(BOB)FileSystemStudy:ResultsFilesystemconfigurationAtomicityOrderingOnesectoroverwriteAppendcontentManysectoroverwriteDirectoryoperationOverwrite→AnyopAppend→AnyopDir-op→AnyopAppend→Renameext2asyncsyncext3writebackordereddata-journalext4writebackorderedno-delallocdata-journalbtrfsxfsdefaultwsyncFileSystemStudy:ResultsFilesystemconfigurationAtomicityOrderingOnesectoroverwriteAppendcontentManysectoroverwriteDirectoryoperationOverwrite→AnyopAppend→AnyopDir-op→AnyopAppend→Renameext2asyncsyncext3writebackordereddata-journalext4writebackorderedno-delallocdata-journalbtrfsxfsdefaultwsyncFileSystemDifferentConfigurationsofFileSystemFileSystemStudy:ResultsFilesystemconfigurationAtomicityOrderingOnesectoroverwriteAppendcontentManysectoroverwriteDirectoryoperationOverwrite→AnyopAppend→AnyopDir-op→AnyopAppend→Renameext2asyncsyncext3writebackordereddata-journalext4writebackorderedno-delallocdata-journalbtrfsxfsdefaultwsyncPersistencePropertiesconsideredFileSystemStudy:ResultsFilesystemconfigurationAtomicityOrderingOnesectoroverwriteAppendcontentManysectoroverwriteDirectoryoperationOverwrite→AnyopAppend→AnyopDir-op→AnyopAppend→Renameext2asyncsyncext3writebackordereddata-journalext4writebackorderedno-delallocdata-journalbtrfsxfsdefaultwsyncIsadirectoryoperation,likerename(),atomiconasystemcrashFileSystemStudy:ResultsFilesystemconfigurationAtomicityOrderingOnesectoroverwriteAppendcontentManysectoroverwriteDirectoryoperationOverwrite→AnyopAppend→AnyopDir-op→AnyopAppend→Renameext2asyncsyncext3writebackordereddata-journalext4writebackorderedno-delallocdata-journalbtrfsxfsdefaultwsyncPropertycertainlynotobeyedWedidnotseeaviolationFileSystemStudy:ResultsFilesystemconfigurationAtomicityOrderingOnesectoroverwriteAppendcontentManysectoroverwriteDirectoryoperationOverwrite→AnyopAppend→AnyopDir-op→AnyopAppend→Renameext2asyncsyncext3writebackordereddata-journalext4writebackorderedno-delallocdata-journalbtrfsxfsdefaultwsyncMainresult:FilesystemsvaryintheirpersistencepropertiesApplicationsshouldnotrelyonpersistencepropertiesTestingapplicationsonaspecificFSisnotenough‐ext3(data-journal):Re-orderingvulnerabilitiesarehiddenFileSystemStudy:ConclusionIntroductionAnExampleBOB:ExaminingFileSystemBehaviorALICE:ExaminingApplicationsConclusionOutlineALICE:Goal"Application-LevelIntelligentCrashExplorer"Goal:Tooltofindcrashvulnerabilitiesofanapplication‐Findvulnerabilitiesacrossallfilesystems‐Relatevulnerabilitiestospecificsourcelines‐RelatevulnerabilitiestofilesystembehaviorALICE:TechniqueUser-suppliedApplicationWorkloadALICEUsersuppliesALICEwithanapplicationworkload–Example:AdatabasetransactionALICE:TechniqueSystem-callTraceALICErunsworkloadandrecordssystem-calltraceALICEUser-suppliedApplicationWorkloadALICE:TechniqueSystem-callTraceAPM:AbstractPersistenceModelAPMmodelsallcrashstatesthatcanoccuronanFS–Default,weakAPMallowsmanypossiblestates–CustomAPMscanbeconfiguredbyuserforaspecificfilesystem–Eg:ext3(ordered)APMallowsstateswithoverwritesre-ordered;ext3(data-journal)APMdoesnotALICEUser-suppliedApplicationWorkloadALICE:TechniqueSystem-callTraceExplorerAPM:AbstractPersistenceModelExplorerreconstructssomestatesusingtheAPMALICEUser-suppliedApplicationWorkloadALICE:TechniqueSystem-callTraceExplorer.
.
.
ALICEAPM:AbstractPersistenceModelCrashstate#1(Violatesatomicityofsyscall-1)Crashstate#2(Violatesorderingofsyscall-1and2)Explorertargetsspecificstates–Relatingtoatomicityandre-orderingofeachsyscallUser-suppliedApplicationWorkloadTheapplicationisrunoneachreconstructedstate–Usersuppliesapplicationchecker–Example:WasACIDpreservedALICE:TechniqueSystem-callTraceExplorer.
.
.
User-suppliedApplicationCheckerALICEAPM:AbstractPersistenceModelCrashstate#1(Violatesatomicityofsyscall-1)Crashstate#2(Violatesorderingofsyscall-1and2)User-suppliedApplicationWorkloadCheckershowswhichstatesarerecoveredfromcorrectlyALICE:TechniqueSystem-callTraceExplorer.
.
.
ALICEAPM:AbstractPersistenceModelCrashstate#1(Violatesatomicityofsyscall-1)Crashstate#2(Violatesorderingofsyscall-1and2)CorrectIncorrectUser-suppliedApplicationWorkloadUser-suppliedApplicationCheckerFromcheckeroutputs,wedeterminevulnerabilitiesALICE:TechniqueSystem-callTraceExplorer.
.
.
Crashvulnerability:Re-orderingsyscall-1and2ALICEAPM:AbstractPersistenceModelCrashstate#1(Violatesatomicityofsyscall-1)Crashstate#2(Violatesorderingofsyscall-1and2)CorrectIncorrectUser-suppliedApplicationWorkloadUser-suppliedApplicationCheckerHDFSZooKeeperVMWarePlayerLMDBGDBMLevelDBPostgresHSQLDBSQLiteMercurialGitVulnerabilityStudy:ApplicationsNon-relationalDatabasesRelationalDatabasesVersionControlSystemsVirtualizationSoftwareDistributedServicesExample:Gitcreat(index.
lock)mkdir(o/x)creat(o/x/tmp_y)append(o/x/tmp_y)fsync(o/x/tmp_y)link(o/x/tmp_y,o/x/y)unlink(o/x/tmp_y)append(index.
lock)rename(index.
lock,index)stdout(finishedadd)Readthefullpapertocorrectlyinterpretresults!
creat(index.
lock)mkdir(o/x)creat(o/x/tmp_y)append(o/x/tmp_y)fsync(o/x/tmp_y)link(o/x/tmp_y,o/x/y)unlink(o/x/tmp_y)append(index.
lock)rename(index.
lock,index)stdout(finishedadd)Example:GitAtomicityvulnerabilityWhichsystemcallsneedtobeatomicReadthefullpapertocorrectlyinterpretresults!
creat(index.
lock)mkdir(o/x)creat(o/x/tmp_y)append(o/x/tmp_y)fsync(o/x/tmp_y)link(o/x/tmp_y,o/x/y)unlink(o/x/tmp_y)append(index.
lock)rename(index.
lock,index)stdout(finishedadd)Example:GitAtomicityvulnerabilityOrderingvulnerabilityWhichsystem-callre-orderingscauseincorrectnessReadthefullpapertocorrectlyinterpretresults!
VulnerabilityStudy:Default(Weak)APMReadthefullpapertocorrectlyinterpretresults!
VulnerabilityStudy:Default(Weak)APM60VulnerabilitiesManyresultinsilentdataloss,inaccessibleapplicationsReadthefullpapertocorrectlyinterpretresults!
VulnerabilityStudy:BtrfsAPMReadthefullpapertocorrectlyinterpretresults!
VulnerabilityStudy:BtrfsAPM31VulnerabilitiesReadthefullpapertocorrectlyinterpretresults!
Garbageduringfile-appends‐Affects3applications‐But,partialappendswithactualdata:0vulnerabilitiesFSsafetyheuristicsseeminglydon'thelpmuch‐Only2foundvulnerabilitiesby"Flushdatabeforerename"‐HeuristicsmighthelpothertypesofapplicationsNon-synchronousdirectoryoperations‐Affectsdurabilityof6applicationsWhatFSbehavioraffectsapplicationsIn-depth:WhatFSbehaviorsaffectapplicationsVulnerabilitiesunderotherAPMsInteractionswithapplicationdevelopersHownottointerpretourresultsAnefficientFSdesignwithsafetyvalidatedbyALICEInthepaper.
.
.
FSvaryinbehavioraffectingapplicationconsistency‐ext2,ext3,ext4,btrfs,xfs,reiserfsvaryevenamongtheirdifferentconfigurations‐SubtleimplementationdetailsaffectbehaviorApplicationprotocolsarecomplex,vulnerable‐60vulnerabilitiesunderweakAPM‐Morethanhalfexposedunderext3,ext4,btrfs‐Depend(bydesignorunwittingly)onFSimplementationSummaryApartingnote.
.
.
.
ExperiencedApp-Developer:POSIXdoesn'tletFSesdothatCanyoupointustotheexactPOSIXdocumentationDeveloper:Ican'tfindit,butIremembersomeonesayingsoApartingnote.
.
.
.
ExperiencedApp-Developer:POSIXdoesn'tletFSesdothatCanyoupointustotheexactPOSIXdocumentationDeveloper:Ican'tfindit,butIremembersomeonesayingsoExperiencedAcademic:Realfilesystemsdon'tdothatButdoesjustthatAcademic:Mystudentswouldflunkclassiftheybuiltafilesystemthatway.
.
.
Apartingnote.
.
.
.
ExperiencedApp-Developer:POSIXdoesn'tletFSesdothatCanyoupointustotheexactPOSIXdocumentationDeveloper:Ican'tfindit,butIremembersomeonesayingsoExperiencedAcademic:Realfilesystemsdon'tdothatButdoesjustthatAcademic:Mystudentswouldflunkclassiftheybuiltafilesystemthatway.
.
.
Thankyou!
Downloadtools:http://research.
cs.
wisc.
edu/adsl/Software/alice
Arpaci-Dusseau,RemziH.
Arpaci-DusseauAllFileSystemsAreNotCreatedEqual:OntheComplexityofCraftingCrash-ConsistentApplicationsThanumalayanSankaranarayanaPillai,VijayChidambaram,RamnatthanAlagappan,SamerAl-Kiswany,AndreaC.
Arpaci-Dusseau,RemziH.
Arpaci-DusseauCrashConsistencyMaintainingdatainvariantsacrossasystemcrash‐Example:DatabasetransactionsshouldbeatomicCrashConsistencyMaintainingdatainvariantsacrossasystemcrash‐Example:DatabasetransactionsshouldbeatomicImportantinsystems‐FileSystems‐RelationalDatabases‐Key-ValueStoresCrashConsistencyMaintainingdatainvariantsacrossasystemcrash‐Example:DatabasetransactionsshouldbeatomicImportantinsystems‐FileSystems‐RelationalDatabases‐Key-ValueStoresHardtogetright:ARIESinventedonlyin1992‐ProvingARIEStook5moreyears(1997)Lotsofworkinfilesystemcrashconsistency‐Journaling,copy-on-write,softupdates.
.
.
File-SystemCrashConsistencyLotsofworkinfilesystemcrashconsistency‐Journaling,copy-on-write,softupdates.
.
.
FSconsistencyfocusesoninternalmetadata‐DodirectoriesonlycontainvaliddirectoryentriesFile-SystemCrashConsistencyLotsofworkinfilesystemcrashconsistency‐Journaling,copy-on-write,softupdates.
.
.
FSconsistencyfocusesoninternalmetadata‐DodirectoriesonlycontainvaliddirectoryentriesWhataboutuser-leveldataFile-SystemCrashConsistencyWhatguaranteesdofilesystemsgiveapplications‐Thatcanbeusedforconsistencyofuser-leveldataThisworkstudies.
.
.
Whatguaranteesdofilesystemsgiveapplications‐Thatcanbeusedforconsistencyofuser-leveldataDoapplicationsmaintainconsistencycorrectly‐Importantapplicationsrequireuser-levelconsistency‐Databases,key-valuestores,distributedsystems.
.
.
Thisworkstudies.
.
.
Filesystemguaranteesvarywidely‐Studied16configsofext2,ext3,ext4,btrfs,xfs,reiserfs‐Guaranteesvaryamongconfigsofsamefilesystem‐Guaranteesoftenside-effectsofFSimplementation‐POSIXstandardsofguarantees,ifany,aredebatedWefind.
.
.
Filesystemguaranteesvarywidely‐Studied16configsofext2,ext3,ext4,btrfs,xfs,reiserfs‐Guaranteesvaryamongconfigsofsamefilesystem‐Guaranteesoftenside-effectsofFSimplementation‐POSIXstandardsofguarantees,ifany,aredebatedApplicationsdependonguaranteesinsubtleways‐Studied11applications:Databases,Distributedsystems,Virtualizationsoftware,Key-valuestores,VCS‐60vulnerabilitiesunderaweakfilesystemmodel‐Morethan30vulnerabilitiesunderext3,ext4,btrfsWefind.
.
.
IntroductionAnExampleBOB:ExaminingFileSystemBehaviorALICE:ExaminingApplicationsConclusionOutlineIntroductionAnExampleBOB:ExaminingFileSystemBehaviorALICE:ExaminingApplicationsConclusionOutlineAfileinitiallycontainsthestring"afoo"‐Assumeeachcharacterin"afoo"isablockofdataTask:Atomicallychangethecontentsto"abar"‐Onapowerloss,wemustretrieveeither"afoo"or"abar"ToyExample:OverviewToyExample:SimpleOverwriteInitialstate/x/f1"afoo"Finalstate/x/f1"abar"Modificationpwrite(/x/f1,2,"bar")IntermediatestatespossibleoncrashToyExample:SimpleOverwriteInitialstate/x/f1"afoo"Modificationpwrite(/x/f1,2,"bar")Finalstate/x/f1"abar"Intermediatestate1/x/f1"aboo"Intermediatestate2/x/f1"afar"Intermediatestates3,4,5.
.
.
.
WhatifcrashatomicityisneededUseapplication-levellogging(a.
k.
a.
undologging/rollbackjournaling)a.
Makeacopyofolddatain"log"fileb.
Modifyactualfilec.
Deletelogfiled.
Onacrash,datacanberecoveredfromthelogToyExample:MaintainingConsistencyWhatifcrashatomicityisneededUpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,foo");pwrite(/x/f1,2,"bar");unlink(/x/log1);WritetologActualmodificationDeletelogToyExample:Protocol#1Worksinext3(data-journal)!
UpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,foo");pwrite(/x/f1,2,"bar");unlink(/x/log1);ToyExample:Protocol#1Somepossibleintermediatestates/x/f1"afoo"/x/log1""/x/f1"afoo"/x/log1"2,3,f"/x/f1"aboo"/x/log1"2,3,foo"1.
2.
3.
Worksinext3(data-journal)!
UpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,foo");pwrite(/x/f1,2,"bar");unlink(/x/log1);Somepossibleintermediatestates/x/f1"afoo"/x/log1""/x/f1"afoo"/x/log1"2,3,f"/x/f1"aboo"/x/log1"2,3,foo"1.
2.
3.
ToyExample:Protocol#1SimplydeletelogfileduringrecoveryWorksinext3(data-journal)!
UpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,foo");pwrite(/x/f1,2,"bar");unlink(/x/log1);Somepossibleintermediatestates/x/f1"afoo"/x/log1""/x/f1"afoo"/x/log1"2,3,f"/x/f1"aboo"/x/log1"2,3,foo"1.
2.
3.
ToyExample:Protocol#1RecoverfromlogfileduringrecoveryWorksinext3(data-journal)!
Doesn'tworkinext3(data-ordered)UpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,foo");pwrite(/x/f1,2,"bar");unlink(/x/log1);ToyExample:Protocol#1Worksinext3(data-journal)!
Doesn'tworkinext3(data-ordered)UpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,foo");pwrite(/x/f1,2,"bar");unlink(/x/log1);ext3(ordered)canre-orderthesetworequests,sendingpwrite(f1)todiskfirst,beforewrite(log1)ToyExample:Protocol#1Worksinext3(data-journal)!
Doesn'tworkinext3(data-ordered)UpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,foo");pwrite(/x/f1,2,"bar");unlink(/x/log1);Apossibleintermediatestate/x/f1"aboo"/x/log1""Recoverynotpossible!
ToyExample:Protocol#1Worksinext3(data-journal),(data-ordered)!
UpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,foo");fsync(/x/log1);pwrite(/x/f1,2,"bar");fsync(/x/f1);unlink(/x/log1);ToyExample:Protocol#2Worksinext3(data-journal),(data-ordered)!
Doesn'tworkinext3(writeback)UpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,foo");fsync(/x/log1);pwrite(/x/f1,2,"bar");fsync(/x/f1);unlink(/x/log1);Apossibleintermediatestates/x/f1"afoo"/x/log1"2,3,#!
@"Filesizealoneincreasesforlog1,andgarbageoccurs.
Recoverycannotdifferentiatebetweengarbageanddata!
CrashhereToyExample:Protocol#2Worksinext3(data-journal),(data-ordered),(writeback)UpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,checksum,foo");fsync(/x/log1);pwrite(/x/f1,2,"bar");fsync(/x/f1);unlink(/x/log1);ToyExample:Protocol#3Worksinext3(data-journal),(data-ordered),(writeback)Notenough,accordingtoLinuxmanpagesUpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,checksum,foo");fsync(/x/log1);pwrite(/x/f1,2,"bar");fsync(/x/f1);unlink(/x/log1);Apossibleintermediatestates/x/f1"aboo"Thelogfile'sdirectoryentrymightneverbecreatedToyExample:Protocol#3WorksinallfilesystemsUpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,checksum,foo");fsync(/x/log1);fsync(/x);pwrite(/x/f1,2,"bar");fsync(/x/f1);unlink(/x/log1);ToyExample:Protocol#4Worksinallfilesystems(Additionalfsync()requiredfordurabilityinallFS)UpdateProtocolcreat(/x/log1);write(/x/log1,"2,3,checksum,foo");fsync(/x/log1);fsync(/x);pwrite(/x/f1,2,"bar");fsync(/x/f1);unlink(/x/log1);fsync(/x);ToyExample:Protocol#5Filesystemsvaryincrash-relatedbehavior‐ext3(ordered)re-orders,whileext3(journaled)doesnotApplicationsusuallydependonsomebehavior‐Dependonordering:Somefsync()callscanbeomittedExample:SummaryIntroductionAnExampleBOB:ExaminingFileSystemBehaviorALICE:ExaminingApplicationsConclusionOutlineTwoclassesofproperties:atomicityandordering‐Atomicityexample:Isawrite()callatomicintheFS‐Orderingexample:Arewrite()callssenttodiskin-orderStudiedext2,ext3,ext4,btrfs,xfs,reiserfs‐Westudied16configurationsofthesixfilesystemsFSBehavior:PersistenceProperties1.
Runuser-levelworkloadsstressingtheproperty‐Example:write(8KB)fortestingatomicityofwrite()callsMethodology:TheBlock-OrderBreaker(BOB)1.
Runuser-levelworkloadsstressingtheproperty‐Example:write(8KB)fortestingatomicityofwrite()calls2.
Recordblock-leveltraceoftheworkloadMethodology:TheBlock-OrderBreaker(BOB)1.
Runuser-levelworkloadsstressingtheproperty‐Example:write(8KB)fortestingatomicityofwrite()calls2.
Recordblock-leveltraceoftheworkload3.
Reconstructdisk-statespossibleonapower-loss‐Allstatespossibleifdisk-cachedoesnotre-order‐Afewstateswheredisk-cachere-ordersMethodology:TheBlock-OrderBreaker(BOB)1.
Runuser-levelworkloadsstressingtheproperty‐Example:write(8KB)fortestingatomicityofwrite()calls2.
Recordblock-leveltraceoftheworkload3.
Reconstructdisk-statespossibleonapower-loss‐Allstatespossibleifdisk-cachedoesnotre-order‐Afewstateswheredisk-cachere-orders4.
RunFSrecovery,verifypropertyoneachdisk-state‐Example:Isall8KBwrittenatomicallyMethodology:TheBlock-OrderBreaker(BOB)FileSystemStudy:ResultsFilesystemconfigurationAtomicityOrderingOnesectoroverwriteAppendcontentManysectoroverwriteDirectoryoperationOverwrite→AnyopAppend→AnyopDir-op→AnyopAppend→Renameext2asyncsyncext3writebackordereddata-journalext4writebackorderedno-delallocdata-journalbtrfsxfsdefaultwsyncFileSystemStudy:ResultsFilesystemconfigurationAtomicityOrderingOnesectoroverwriteAppendcontentManysectoroverwriteDirectoryoperationOverwrite→AnyopAppend→AnyopDir-op→AnyopAppend→Renameext2asyncsyncext3writebackordereddata-journalext4writebackorderedno-delallocdata-journalbtrfsxfsdefaultwsyncFileSystemDifferentConfigurationsofFileSystemFileSystemStudy:ResultsFilesystemconfigurationAtomicityOrderingOnesectoroverwriteAppendcontentManysectoroverwriteDirectoryoperationOverwrite→AnyopAppend→AnyopDir-op→AnyopAppend→Renameext2asyncsyncext3writebackordereddata-journalext4writebackorderedno-delallocdata-journalbtrfsxfsdefaultwsyncPersistencePropertiesconsideredFileSystemStudy:ResultsFilesystemconfigurationAtomicityOrderingOnesectoroverwriteAppendcontentManysectoroverwriteDirectoryoperationOverwrite→AnyopAppend→AnyopDir-op→AnyopAppend→Renameext2asyncsyncext3writebackordereddata-journalext4writebackorderedno-delallocdata-journalbtrfsxfsdefaultwsyncIsadirectoryoperation,likerename(),atomiconasystemcrashFileSystemStudy:ResultsFilesystemconfigurationAtomicityOrderingOnesectoroverwriteAppendcontentManysectoroverwriteDirectoryoperationOverwrite→AnyopAppend→AnyopDir-op→AnyopAppend→Renameext2asyncsyncext3writebackordereddata-journalext4writebackorderedno-delallocdata-journalbtrfsxfsdefaultwsyncPropertycertainlynotobeyedWedidnotseeaviolationFileSystemStudy:ResultsFilesystemconfigurationAtomicityOrderingOnesectoroverwriteAppendcontentManysectoroverwriteDirectoryoperationOverwrite→AnyopAppend→AnyopDir-op→AnyopAppend→Renameext2asyncsyncext3writebackordereddata-journalext4writebackorderedno-delallocdata-journalbtrfsxfsdefaultwsyncMainresult:FilesystemsvaryintheirpersistencepropertiesApplicationsshouldnotrelyonpersistencepropertiesTestingapplicationsonaspecificFSisnotenough‐ext3(data-journal):Re-orderingvulnerabilitiesarehiddenFileSystemStudy:ConclusionIntroductionAnExampleBOB:ExaminingFileSystemBehaviorALICE:ExaminingApplicationsConclusionOutlineALICE:Goal"Application-LevelIntelligentCrashExplorer"Goal:Tooltofindcrashvulnerabilitiesofanapplication‐Findvulnerabilitiesacrossallfilesystems‐Relatevulnerabilitiestospecificsourcelines‐RelatevulnerabilitiestofilesystembehaviorALICE:TechniqueUser-suppliedApplicationWorkloadALICEUsersuppliesALICEwithanapplicationworkload–Example:AdatabasetransactionALICE:TechniqueSystem-callTraceALICErunsworkloadandrecordssystem-calltraceALICEUser-suppliedApplicationWorkloadALICE:TechniqueSystem-callTraceAPM:AbstractPersistenceModelAPMmodelsallcrashstatesthatcanoccuronanFS–Default,weakAPMallowsmanypossiblestates–CustomAPMscanbeconfiguredbyuserforaspecificfilesystem–Eg:ext3(ordered)APMallowsstateswithoverwritesre-ordered;ext3(data-journal)APMdoesnotALICEUser-suppliedApplicationWorkloadALICE:TechniqueSystem-callTraceExplorerAPM:AbstractPersistenceModelExplorerreconstructssomestatesusingtheAPMALICEUser-suppliedApplicationWorkloadALICE:TechniqueSystem-callTraceExplorer.
.
.
ALICEAPM:AbstractPersistenceModelCrashstate#1(Violatesatomicityofsyscall-1)Crashstate#2(Violatesorderingofsyscall-1and2)Explorertargetsspecificstates–Relatingtoatomicityandre-orderingofeachsyscallUser-suppliedApplicationWorkloadTheapplicationisrunoneachreconstructedstate–Usersuppliesapplicationchecker–Example:WasACIDpreservedALICE:TechniqueSystem-callTraceExplorer.
.
.
User-suppliedApplicationCheckerALICEAPM:AbstractPersistenceModelCrashstate#1(Violatesatomicityofsyscall-1)Crashstate#2(Violatesorderingofsyscall-1and2)User-suppliedApplicationWorkloadCheckershowswhichstatesarerecoveredfromcorrectlyALICE:TechniqueSystem-callTraceExplorer.
.
.
ALICEAPM:AbstractPersistenceModelCrashstate#1(Violatesatomicityofsyscall-1)Crashstate#2(Violatesorderingofsyscall-1and2)CorrectIncorrectUser-suppliedApplicationWorkloadUser-suppliedApplicationCheckerFromcheckeroutputs,wedeterminevulnerabilitiesALICE:TechniqueSystem-callTraceExplorer.
.
.
Crashvulnerability:Re-orderingsyscall-1and2ALICEAPM:AbstractPersistenceModelCrashstate#1(Violatesatomicityofsyscall-1)Crashstate#2(Violatesorderingofsyscall-1and2)CorrectIncorrectUser-suppliedApplicationWorkloadUser-suppliedApplicationCheckerHDFSZooKeeperVMWarePlayerLMDBGDBMLevelDBPostgresHSQLDBSQLiteMercurialGitVulnerabilityStudy:ApplicationsNon-relationalDatabasesRelationalDatabasesVersionControlSystemsVirtualizationSoftwareDistributedServicesExample:Gitcreat(index.
lock)mkdir(o/x)creat(o/x/tmp_y)append(o/x/tmp_y)fsync(o/x/tmp_y)link(o/x/tmp_y,o/x/y)unlink(o/x/tmp_y)append(index.
lock)rename(index.
lock,index)stdout(finishedadd)Readthefullpapertocorrectlyinterpretresults!
creat(index.
lock)mkdir(o/x)creat(o/x/tmp_y)append(o/x/tmp_y)fsync(o/x/tmp_y)link(o/x/tmp_y,o/x/y)unlink(o/x/tmp_y)append(index.
lock)rename(index.
lock,index)stdout(finishedadd)Example:GitAtomicityvulnerabilityWhichsystemcallsneedtobeatomicReadthefullpapertocorrectlyinterpretresults!
creat(index.
lock)mkdir(o/x)creat(o/x/tmp_y)append(o/x/tmp_y)fsync(o/x/tmp_y)link(o/x/tmp_y,o/x/y)unlink(o/x/tmp_y)append(index.
lock)rename(index.
lock,index)stdout(finishedadd)Example:GitAtomicityvulnerabilityOrderingvulnerabilityWhichsystem-callre-orderingscauseincorrectnessReadthefullpapertocorrectlyinterpretresults!
VulnerabilityStudy:Default(Weak)APMReadthefullpapertocorrectlyinterpretresults!
VulnerabilityStudy:Default(Weak)APM60VulnerabilitiesManyresultinsilentdataloss,inaccessibleapplicationsReadthefullpapertocorrectlyinterpretresults!
VulnerabilityStudy:BtrfsAPMReadthefullpapertocorrectlyinterpretresults!
VulnerabilityStudy:BtrfsAPM31VulnerabilitiesReadthefullpapertocorrectlyinterpretresults!
Garbageduringfile-appends‐Affects3applications‐But,partialappendswithactualdata:0vulnerabilitiesFSsafetyheuristicsseeminglydon'thelpmuch‐Only2foundvulnerabilitiesby"Flushdatabeforerename"‐HeuristicsmighthelpothertypesofapplicationsNon-synchronousdirectoryoperations‐Affectsdurabilityof6applicationsWhatFSbehavioraffectsapplicationsIn-depth:WhatFSbehaviorsaffectapplicationsVulnerabilitiesunderotherAPMsInteractionswithapplicationdevelopersHownottointerpretourresultsAnefficientFSdesignwithsafetyvalidatedbyALICEInthepaper.
.
.
FSvaryinbehavioraffectingapplicationconsistency‐ext2,ext3,ext4,btrfs,xfs,reiserfsvaryevenamongtheirdifferentconfigurations‐SubtleimplementationdetailsaffectbehaviorApplicationprotocolsarecomplex,vulnerable‐60vulnerabilitiesunderweakAPM‐Morethanhalfexposedunderext3,ext4,btrfs‐Depend(bydesignorunwittingly)onFSimplementationSummaryApartingnote.
.
.
.
ExperiencedApp-Developer:POSIXdoesn'tletFSesdothatCanyoupointustotheexactPOSIXdocumentationDeveloper:Ican'tfindit,butIremembersomeonesayingsoApartingnote.
.
.
.
ExperiencedApp-Developer:POSIXdoesn'tletFSesdothatCanyoupointustotheexactPOSIXdocumentationDeveloper:Ican'tfindit,butIremembersomeonesayingsoExperiencedAcademic:Realfilesystemsdon'tdothatButdoesjustthatAcademic:Mystudentswouldflunkclassiftheybuiltafilesystemthatway.
.
.
Apartingnote.
.
.
.
ExperiencedApp-Developer:POSIXdoesn'tletFSesdothatCanyoupointustotheexactPOSIXdocumentationDeveloper:Ican'tfindit,butIremembersomeonesayingsoExperiencedAcademic:Realfilesystemsdon'tdothatButdoesjustthatAcademic:Mystudentswouldflunkclassiftheybuiltafilesystemthatway.
.
.
Thankyou!
Downloadtools:http://research.
cs.
wisc.
edu/adsl/Software/alice
- pwrite卡巴斯基授权文件相关文档
- 标准卡巴斯基授权文件
- 信息卡巴斯基授权文件
- 信任卡巴斯基授权文件
- 数据卡巴斯基授权文件
- 居中卡巴斯基授权文件
- 节点卡巴斯基授权文件
云雀云（larkyun）低至368元/月，广州移动1Gbps带宽VDS（带100G防御），常州联通1Gbps带宽VDS
云雀云（larkyun）当前主要运作国内线路的机器，最大提供1Gbps服务器，有云服务器（VDS）、也有独立服务器，对接国内、国外的效果都是相当靠谱的。此外，还有台湾hinet线路的动态云服务器和静态云服务器。当前，larkyun对广州移动二期正在搞优惠促销！官方网站：https://larkyun.top付款方式：支付宝、微信、USDT广移二期开售8折折扣码：56NZVE0YZN （试用于常州联...
妮妮云香港CTG云服务器1核 1G 3M19元/月
香港ctg云服务器香港ctg云服务器官网链接 点击进入妮妮云官网优惠活动 香港CTG云服务器地区CPU内存硬盘带宽IP价格购买地址香港1核1G20G3M5个19元/月点击购买香港2核2G30G5M10个40元/月点击购买香港2核2G40G5M20个450元/月点击购买香港4核4G50G6M30个80元/月点击购买香...
美国200G美国高防服务器16G，800元
美国高防服务器提速啦专业提供美国高防服务器，美国高防服务器租用，美国抗攻击服务器，高防御美国服务器租用等。我们的海外高防服务器带给您坚不可摧的DDoS防护，保障您的业务不受攻击影响。HostEase美国高防服务器位于加州和洛杉矶数据中心，均为国内访问速度最快最稳定的美国抗攻击机房，带给您快速的访问体验。我们的高防服务器配有最高层级的DDoS防护系统，每款抗攻击服务器均拥有免费DDoS防护额度，让您...
卡巴斯基授权文件为你推荐
-
51自学网站推荐一个好一点的自学网站，关于网站建设的。湖南商标注册湖南商标注册代办公司万网核心代理我想买个域名和空间，我一朋友给我介绍万网代理环宇网络空间商，他们的空间稳定吗，价格怎么样，咨询师的服flash导航条如何制作flash导航条依赖注入Spring 的依赖注入是什么意思?二叉树遍历怎么正确理解二叉树的遍历自助建站自助建站到底好还是不好不兼容vivo手机和软件不兼容怎么办?镜像文件是什么什么是镜像文件啊网店推广网站网店怎么推广？