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
AlphaVPS（€3.99/月）VPS年付15欧，AMD EYPC+NVMe系列起
AlphaVPS是一家保加利亚本土主机商(DA International Group Ltd)，提供VPS主机及独立服务器租用等，数据中心包括美国(洛杉矶/纽约)、德国、英国和保加利亚等，公司办公地点跟他们提供的保加利亚数据中心在一栋楼内，自有硬件，提供IPv4+IPv6，支持PayPal或者信用卡等方式付款。商家提供的大硬盘VPS主机，提供128GB-2TB磁盘，最低年付15欧元起，也可以选择...
Spinservers：美国圣何塞机房少量补货/双E5/64GB DDR4/2TB SSD/10Gbps端口月流量10TB/$111/月
Chia矿机，Spinservers怎么样？Spinservers好不好，Spinservers大硬盘服务器。Spinservers刚刚在美国圣何塞机房补货120台独立服务器，CPU都是双E5系列，64-512GB DDR4内存，超大SSD或NVMe存储，数量有限，机器都是预部署好的，下单即可上架，无需人工干预，有需要的朋友抓紧下单哦。Spinservers是Majestic Hosting So...
iWebFusion：独立服务器月付57美元起/5个机房可选,10Gbps服务器月付149美元起
iWebFusion(iWFHosting)在部落分享过很多次了，这是成立于2001年的老牌国外主机商H4Y旗下站点，提供的产品包括虚拟主机、VPS和独立服务器租用等等，其中VPS主机基于KVM架构，数据中心可选美国洛杉矶、北卡、本德、蒙蒂塞洛等。商家独立服务器可选5个不同机房，最低每月57美元起，而大流量10Gbps带宽服务器也仅149美元起。首先我们分享几款常规服务器配置信息，以下机器可选择5...
卡巴斯基授权文件为你推荐
-
吴晓波频道买粉《充电时间》的节目跟《吴晓波频道》哪个好听？今日热点怎么删除千牛里面的今日热点怎么取消_？如何建立一个网站如何建立一个网站？iphone越狱后怎么恢复苹果手机越狱之后能恢复原来吗？网易公开课怎么下载如何下载网易公开课xv播放器下载求手机可以看xv格式的视频播放器网络广告投放网络广告投放有哪些技巧？三星s8什么时候上市三星s8什么时候上市 三星s8上市时间如何清理ie缓存怎么清除IE缓存.微信怎么看聊天记录怎样才能调取微信聊天记录