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
百纵科技（1399元/月)香港CN2站群232IP
湖南百纵科技有限公司是一家具有ISP ICP 电信增值许可证的正规公司，多年不断转型探索现已颇具规模，公司成立于2009年 通过多年经营积累目前已独具一格，公司主要经营有国内高防服务器,香港服务器,美国服务器,站群服务器,东南亚服务器租用，国内香港美国云服务器，以及全球专线业务！活动方案：主营：1、美国CN2云服务器,美国VPS，美国高防云主机,美国独立服务器,美国站群服务器,美国母机。2、香港C...
justhost：“第4次VPS测评”，8.3元/月，200M带宽，不限流量，KVM虚拟，4个俄罗斯机房应有适合你的
justhost.ru官方来消息说已经对网络进行了比较全面的优化，针对中国电信、联通、移动来说，4个机房总有一个适合中国用户，让站长进行一下测试，这不就有了这篇有关justhost的VPS的第四次测评。本帖主要关注的是网络，对于其他的参数一概不管！ 官方网站：https://justhost.ru 最低配VPS：8.3元/月，KVM，512M内存，5G硬盘，200M带宽，不限流量 购买链接：...
LOCVPS洛杉矶CN2线路KVM上线,洛杉矶/香港云地/香港邦联7折
LOCVPS发来了新的洛杉矶CN2线路主机上线通知，基于KVM架构，目前可与香港云地、香港邦联机房XEN架构主机一起适用7折优惠码，优惠后最低美国洛杉矶CN2线路KVM架构2GB内存套餐月付38.5元起。LOCPVS是一家成立较早的国人VPS服务商，目前提供洛杉矶MC、洛杉矶C3、和香港邦联、香港沙田电信、香港大埔、日本东京、日本大阪、新加坡、德国和荷兰等机房VPS主机，基于KVM或者XEN架构。...
卡巴斯基授权文件为你推荐
-
木马病毒木马病毒是什么?快递打印快递单可以自己打印吗安装程序配置服务器失败安装用友u8的数据库最后说：“安装程序配置服务器失败。参考服务器错误日志和 C:WINDOWSsqlstp.log 了解更多信息。”淘宝收费淘宝网的收费项目有哪些快速美白好方法脸部快速美白有什么好方法啊bluestacks安卓模拟器BlueStacks如何安装使用？bluestacksbluestacks怎么用？手机区号手机号码安卓应用平台app应用平台有哪些 应用平台哪些网店推广网站开网店如何做推广?