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wangjin / seek-for-android

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Access Control mechanism on Smartcard 2.4.0 + GPAC #48

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago 
According to GP Secure Element AC spec 1.0 (section 4.2), there are 2 ways for 
the Enforcer to be implemented:  1. Pre-Cache Rules and Refresh Tag mechanism.  
2. Instant Query mechanism, which means that the access control enforcer would 
never query rules up front; instead, on each open logical channel action, the 
Access Control enforcer retrieves the rules associated to the AID & the cert 
hash from ARA applet to determine the permission.   

Looking into the code of SC 2.4, it seems to me that the implementation does 
not follow any of the two mechanisms that GP specified.

Here is a scenario that could cause an error to evaluate access control rules:

1. App-A opens a logical channel to AID-1. As a result, GPAC enforcer loads the 
access control rules associated with AID-1.
2. App-B opens a logical channel to AID-2. As a result, GPAC enforcer loads the 
access control rules associated with AID-2.
3. OTA adds an access control rule to AID-2.  The value of Refresh tag is 
changed accordingly.
4. App-A opens a logical channel to AID-1. As the value of Refresh Tag is 
changed, GPAC enforcer re-loads the access control rules associated to AID-1.  
The new value of Refresh Tag also replaces the current Refresh tag.
5. App-B opens a logical channel to AID-2. Due to the value of Refresh Tag is 
unchanged, GPAC enforcer uses the cashed access control rules associated to 
AID-2, which is out of date as the rules have been changed since step 3.

Original issue reported on code.google.com by danny.w....@gmail.com on 8 Feb 2013 at 5:00

GoogleCodeExporter commented 9 years ago 
After another review of code, I've realized that I am mistaken on this bug 
report.  According to the code, the entire cached access control rules will be 
reset when a different value of Refresh Tag is found.  Thus, on the step 5, 
App-B will retrieve those access control rules associated to AID-2 even though 
the Refresh Tag is the same.

It's not a defect.

Original comment by danny.w....@gmail.com on 11 Feb 2013 at 7:23

GoogleCodeExporter commented 9 years ago 
see #1

Original comment by schus...@gmail.com on 18 Mar 2013 at 2:47