Why does Windows process all NTFS child objects when changing a parent’s ACL?











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Why does Windows process all NTFS child objects when changing a parent’s ACL?



I would expect this behavior if I had checked the “Replace all child object permissions...” box, but even when that box is left unchecked, Windows will process all the children.










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  • @Ben It is not done by the shell, because the cascade of inherited permissions must be replicated to all child objects with inherit enabled, so it has to be done even when calling the Windows API directly. FYI: Permissions are replicated for performance reasons.
    – Andreas
    yesterday

















up vote
8
down vote

favorite
1












Why does Windows process all NTFS child objects when changing a parent’s ACL?



I would expect this behavior if I had checked the “Replace all child object permissions...” box, but even when that box is left unchecked, Windows will process all the children.










share|improve this question






















  • @Ben It is not done by the shell, because the cascade of inherited permissions must be replicated to all child objects with inherit enabled, so it has to be done even when calling the Windows API directly. FYI: Permissions are replicated for performance reasons.
    – Andreas
    yesterday















up vote
8
down vote

favorite
1









up vote
8
down vote

favorite
1






1





Why does Windows process all NTFS child objects when changing a parent’s ACL?



I would expect this behavior if I had checked the “Replace all child object permissions...” box, but even when that box is left unchecked, Windows will process all the children.










share|improve this question













Why does Windows process all NTFS child objects when changing a parent’s ACL?



I would expect this behavior if I had checked the “Replace all child object permissions...” box, but even when that box is left unchecked, Windows will process all the children.







windows ntfs






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asked 2 days ago









Corey

81292747




81292747












  • @Ben It is not done by the shell, because the cascade of inherited permissions must be replicated to all child objects with inherit enabled, so it has to be done even when calling the Windows API directly. FYI: Permissions are replicated for performance reasons.
    – Andreas
    yesterday




















  • @Ben It is not done by the shell, because the cascade of inherited permissions must be replicated to all child objects with inherit enabled, so it has to be done even when calling the Windows API directly. FYI: Permissions are replicated for performance reasons.
    – Andreas
    yesterday


















@Ben It is not done by the shell, because the cascade of inherited permissions must be replicated to all child objects with inherit enabled, so it has to be done even when calling the Windows API directly. FYI: Permissions are replicated for performance reasons.
– Andreas
yesterday






@Ben It is not done by the shell, because the cascade of inherited permissions must be replicated to all child objects with inherit enabled, so it has to be done even when calling the Windows API directly. FYI: Permissions are replicated for performance reasons.
– Andreas
yesterday












3 Answers
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10
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Any child object that is configured to inherit it’s permissions from the parent object will need to be processed. Explicitly defined permissions on the child objects are not affected.



The option, “Replace permissions on all child objects,” will not only propagate the permissions to all child objects but it will also remove and replace any explicitly defined permissions on all child objects.






share|improve this answer




























    up vote
    6
    down vote













    In Windows file permissions are not dynamically inherited. That is, when an attempt is made to open a file Windows only looks at the ACL of that file and not at the ACLs of the directories in the tree containing the file. That means when you change the ACL of a directory Windows has to immediately update the permissions of all files and subdirectories within the affected directory.



    In Windows the inherit setting in an ACL does not indicate any form of dynamic inheritance. It is just a flag to indicate that when a parent directory's ACL is modified all files and subdirectories in the tree that have the inherit flag set must also be updated.



    Those of us old enough to remember Novell NetWare will remember this was one of the big differences from NetWare because in NetWare inheritance of permissions is (was?) dynamic. There was much debate at the time about which approach was better, though history has rendered the issue moot. Dynamic ACLs require the OS to check the ACLs of every parent directory at the time an attempt is made to open the file, but changing ACLs is quick. In Windows opening file requires only a single ACL to be checked, but as you've found it means changing a directory ACL can be slow.






    share|improve this answer

















    • 1




      This makes perfect sense. ACLs are read a lot more than they're written, so it makes sense to cache the "inherited value" for faster read access, at the cost of more complexity in the rarer write use case.
      – Alexander
      yesterday










    • @Alexander: What I don't understand is why this complexity has to be exposed to the end user. Why not lie and tell the end user "it's dynamic" but cache things internally?
      – Kevin
      yesterday










    • @Kevin - because it can take some time to propagate permissions and in that time period you enforcement of permissions might not happen as you expect?
      – davidbak
      yesterday


















    up vote
    3
    down vote













    By default, child folders inherit permissions from the parent folder. Assuming the default scope when you're adding/modifying permissions on the parent folder (this folder, subfolders and files) then all child folders will be updated to reflect the permissions change at the parent.



    The checkbox you're referring to is a "one time" operation that will remove all explicitly defined permissions on all child folders and replace them with inheritable permissions from the parent and will re-enable permissions inheritance on the child folders.






    share|improve this answer





















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      3 Answers
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      3 Answers
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      up vote
      10
      down vote













      Any child object that is configured to inherit it’s permissions from the parent object will need to be processed. Explicitly defined permissions on the child objects are not affected.



      The option, “Replace permissions on all child objects,” will not only propagate the permissions to all child objects but it will also remove and replace any explicitly defined permissions on all child objects.






      share|improve this answer

























        up vote
        10
        down vote













        Any child object that is configured to inherit it’s permissions from the parent object will need to be processed. Explicitly defined permissions on the child objects are not affected.



        The option, “Replace permissions on all child objects,” will not only propagate the permissions to all child objects but it will also remove and replace any explicitly defined permissions on all child objects.






        share|improve this answer























          up vote
          10
          down vote










          up vote
          10
          down vote









          Any child object that is configured to inherit it’s permissions from the parent object will need to be processed. Explicitly defined permissions on the child objects are not affected.



          The option, “Replace permissions on all child objects,” will not only propagate the permissions to all child objects but it will also remove and replace any explicitly defined permissions on all child objects.






          share|improve this answer












          Any child object that is configured to inherit it’s permissions from the parent object will need to be processed. Explicitly defined permissions on the child objects are not affected.



          The option, “Replace permissions on all child objects,” will not only propagate the permissions to all child objects but it will also remove and replace any explicitly defined permissions on all child objects.







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered 2 days ago









          Appleoddity

          1,8941315




          1,8941315
























              up vote
              6
              down vote













              In Windows file permissions are not dynamically inherited. That is, when an attempt is made to open a file Windows only looks at the ACL of that file and not at the ACLs of the directories in the tree containing the file. That means when you change the ACL of a directory Windows has to immediately update the permissions of all files and subdirectories within the affected directory.



              In Windows the inherit setting in an ACL does not indicate any form of dynamic inheritance. It is just a flag to indicate that when a parent directory's ACL is modified all files and subdirectories in the tree that have the inherit flag set must also be updated.



              Those of us old enough to remember Novell NetWare will remember this was one of the big differences from NetWare because in NetWare inheritance of permissions is (was?) dynamic. There was much debate at the time about which approach was better, though history has rendered the issue moot. Dynamic ACLs require the OS to check the ACLs of every parent directory at the time an attempt is made to open the file, but changing ACLs is quick. In Windows opening file requires only a single ACL to be checked, but as you've found it means changing a directory ACL can be slow.






              share|improve this answer

















              • 1




                This makes perfect sense. ACLs are read a lot more than they're written, so it makes sense to cache the "inherited value" for faster read access, at the cost of more complexity in the rarer write use case.
                – Alexander
                yesterday










              • @Alexander: What I don't understand is why this complexity has to be exposed to the end user. Why not lie and tell the end user "it's dynamic" but cache things internally?
                – Kevin
                yesterday










              • @Kevin - because it can take some time to propagate permissions and in that time period you enforcement of permissions might not happen as you expect?
                – davidbak
                yesterday















              up vote
              6
              down vote













              In Windows file permissions are not dynamically inherited. That is, when an attempt is made to open a file Windows only looks at the ACL of that file and not at the ACLs of the directories in the tree containing the file. That means when you change the ACL of a directory Windows has to immediately update the permissions of all files and subdirectories within the affected directory.



              In Windows the inherit setting in an ACL does not indicate any form of dynamic inheritance. It is just a flag to indicate that when a parent directory's ACL is modified all files and subdirectories in the tree that have the inherit flag set must also be updated.



              Those of us old enough to remember Novell NetWare will remember this was one of the big differences from NetWare because in NetWare inheritance of permissions is (was?) dynamic. There was much debate at the time about which approach was better, though history has rendered the issue moot. Dynamic ACLs require the OS to check the ACLs of every parent directory at the time an attempt is made to open the file, but changing ACLs is quick. In Windows opening file requires only a single ACL to be checked, but as you've found it means changing a directory ACL can be slow.






              share|improve this answer

















              • 1




                This makes perfect sense. ACLs are read a lot more than they're written, so it makes sense to cache the "inherited value" for faster read access, at the cost of more complexity in the rarer write use case.
                – Alexander
                yesterday










              • @Alexander: What I don't understand is why this complexity has to be exposed to the end user. Why not lie and tell the end user "it's dynamic" but cache things internally?
                – Kevin
                yesterday










              • @Kevin - because it can take some time to propagate permissions and in that time period you enforcement of permissions might not happen as you expect?
                – davidbak
                yesterday













              up vote
              6
              down vote










              up vote
              6
              down vote









              In Windows file permissions are not dynamically inherited. That is, when an attempt is made to open a file Windows only looks at the ACL of that file and not at the ACLs of the directories in the tree containing the file. That means when you change the ACL of a directory Windows has to immediately update the permissions of all files and subdirectories within the affected directory.



              In Windows the inherit setting in an ACL does not indicate any form of dynamic inheritance. It is just a flag to indicate that when a parent directory's ACL is modified all files and subdirectories in the tree that have the inherit flag set must also be updated.



              Those of us old enough to remember Novell NetWare will remember this was one of the big differences from NetWare because in NetWare inheritance of permissions is (was?) dynamic. There was much debate at the time about which approach was better, though history has rendered the issue moot. Dynamic ACLs require the OS to check the ACLs of every parent directory at the time an attempt is made to open the file, but changing ACLs is quick. In Windows opening file requires only a single ACL to be checked, but as you've found it means changing a directory ACL can be slow.






              share|improve this answer












              In Windows file permissions are not dynamically inherited. That is, when an attempt is made to open a file Windows only looks at the ACL of that file and not at the ACLs of the directories in the tree containing the file. That means when you change the ACL of a directory Windows has to immediately update the permissions of all files and subdirectories within the affected directory.



              In Windows the inherit setting in an ACL does not indicate any form of dynamic inheritance. It is just a flag to indicate that when a parent directory's ACL is modified all files and subdirectories in the tree that have the inherit flag set must also be updated.



              Those of us old enough to remember Novell NetWare will remember this was one of the big differences from NetWare because in NetWare inheritance of permissions is (was?) dynamic. There was much debate at the time about which approach was better, though history has rendered the issue moot. Dynamic ACLs require the OS to check the ACLs of every parent directory at the time an attempt is made to open the file, but changing ACLs is quick. In Windows opening file requires only a single ACL to be checked, but as you've found it means changing a directory ACL can be slow.







              share|improve this answer












              share|improve this answer



              share|improve this answer










              answered yesterday









              John Rennie

              7,33311829




              7,33311829








              • 1




                This makes perfect sense. ACLs are read a lot more than they're written, so it makes sense to cache the "inherited value" for faster read access, at the cost of more complexity in the rarer write use case.
                – Alexander
                yesterday










              • @Alexander: What I don't understand is why this complexity has to be exposed to the end user. Why not lie and tell the end user "it's dynamic" but cache things internally?
                – Kevin
                yesterday










              • @Kevin - because it can take some time to propagate permissions and in that time period you enforcement of permissions might not happen as you expect?
                – davidbak
                yesterday














              • 1




                This makes perfect sense. ACLs are read a lot more than they're written, so it makes sense to cache the "inherited value" for faster read access, at the cost of more complexity in the rarer write use case.
                – Alexander
                yesterday










              • @Alexander: What I don't understand is why this complexity has to be exposed to the end user. Why not lie and tell the end user "it's dynamic" but cache things internally?
                – Kevin
                yesterday










              • @Kevin - because it can take some time to propagate permissions and in that time period you enforcement of permissions might not happen as you expect?
                – davidbak
                yesterday








              1




              1




              This makes perfect sense. ACLs are read a lot more than they're written, so it makes sense to cache the "inherited value" for faster read access, at the cost of more complexity in the rarer write use case.
              – Alexander
              yesterday




              This makes perfect sense. ACLs are read a lot more than they're written, so it makes sense to cache the "inherited value" for faster read access, at the cost of more complexity in the rarer write use case.
              – Alexander
              yesterday












              @Alexander: What I don't understand is why this complexity has to be exposed to the end user. Why not lie and tell the end user "it's dynamic" but cache things internally?
              – Kevin
              yesterday




              @Alexander: What I don't understand is why this complexity has to be exposed to the end user. Why not lie and tell the end user "it's dynamic" but cache things internally?
              – Kevin
              yesterday












              @Kevin - because it can take some time to propagate permissions and in that time period you enforcement of permissions might not happen as you expect?
              – davidbak
              yesterday




              @Kevin - because it can take some time to propagate permissions and in that time period you enforcement of permissions might not happen as you expect?
              – davidbak
              yesterday










              up vote
              3
              down vote













              By default, child folders inherit permissions from the parent folder. Assuming the default scope when you're adding/modifying permissions on the parent folder (this folder, subfolders and files) then all child folders will be updated to reflect the permissions change at the parent.



              The checkbox you're referring to is a "one time" operation that will remove all explicitly defined permissions on all child folders and replace them with inheritable permissions from the parent and will re-enable permissions inheritance on the child folders.






              share|improve this answer

























                up vote
                3
                down vote













                By default, child folders inherit permissions from the parent folder. Assuming the default scope when you're adding/modifying permissions on the parent folder (this folder, subfolders and files) then all child folders will be updated to reflect the permissions change at the parent.



                The checkbox you're referring to is a "one time" operation that will remove all explicitly defined permissions on all child folders and replace them with inheritable permissions from the parent and will re-enable permissions inheritance on the child folders.






                share|improve this answer























                  up vote
                  3
                  down vote










                  up vote
                  3
                  down vote









                  By default, child folders inherit permissions from the parent folder. Assuming the default scope when you're adding/modifying permissions on the parent folder (this folder, subfolders and files) then all child folders will be updated to reflect the permissions change at the parent.



                  The checkbox you're referring to is a "one time" operation that will remove all explicitly defined permissions on all child folders and replace them with inheritable permissions from the parent and will re-enable permissions inheritance on the child folders.






                  share|improve this answer












                  By default, child folders inherit permissions from the parent folder. Assuming the default scope when you're adding/modifying permissions on the parent folder (this folder, subfolders and files) then all child folders will be updated to reflect the permissions change at the parent.



                  The checkbox you're referring to is a "one time" operation that will remove all explicitly defined permissions on all child folders and replace them with inheritable permissions from the parent and will re-enable permissions inheritance on the child folders.







                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered 2 days ago









                  joeqwerty

                  94.5k462147




                  94.5k462147






























                       

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