Difference between revisions of "Tom"
Tom Golubev (Talk | contribs) |
Tom Golubev (Talk | contribs) |
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<br> | <br> | ||
| − | '''Task 1:''' Implement setkey(unsigned int k0, unsigned int k1) syscall<br> | + | '''Task 1:''' Implement setkey(unsigned int k0, unsigned int k1) syscall / kcall<br> |
save for up to 8 users<br> | save for up to 8 users<br> | ||
hash on UID -> how?<br> | hash on UID -> how?<br> | ||
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'''Task 2:''' Enable sticky bit (S_ISVTX)<br> | '''Task 2:''' Enable sticky bit (S_ISVTX)<br> | ||
modify the ALL_MODES constant in minix/const.h to be 0007777<br> | modify the ALL_MODES constant in minix/const.h to be 0007777<br> | ||
| + | <br> | ||
| − | + | '''Task 3:''' uspace utility protectfile<br> | |
| − | '''Task 3:''' uspace utility protectfile | + | set sticky bit appropriately by setting sticky bit using chmod scall<br> |
| − | set sticky bit appropriately by setting sticky bit using chmod scall | + | e / d should be done with the sticky bit off to ensure that no e / d is done automatically by the file system.<br> |
| − | e / d should be done with the sticky bit off to ensure that no e / d is done automatically by the file system. | + | <br> |
| − | + | Need to obtain file ID with stat() syscall<br> | |
| − | Need to obtain file ID with stat() syscall | + | |
Latest revision as of 03:57, 5 June 2009
Nomenclature:
scall = system call, the user space part of it; in the library
kcall = call that the scall makes, that will actually encrypt stuff (kernel space)
uspace = user space application (protectfile)
Issues:
do we check for root in scall? we should. kernel shouldnt have to check for that
so the buffer is allocated in the scall. it makes a kcall, and passes the pointer to the scall's buffer, encrypts it and returns
you don't need to be root, any user can set there own key, and e / d their own files
max 8 users as per design
what about user privs? users shouldnt have access to e / d if they dont have rights to a file
Task 1: Implement setkey(unsigned int k0, unsigned int k1) syscall / kcall
save for up to 8 users
hash on UID -> how?
If both k0, k1 == 0, disable encryption: reset key to 0
can use a struct with a key, and uid, valid bit. Make an array of them, search through every attempt, find free spot after the fact. Maybe ineffiecient.
Task 2: Enable sticky bit (S_ISVTX)
modify the ALL_MODES constant in minix/const.h to be 0007777
Task 3: uspace utility protectfile
set sticky bit appropriately by setting sticky bit using chmod scall
e / d should be done with the sticky bit off to ensure that no e / d is done automatically by the file system.
Need to obtain file ID with stat() syscall
