GAP- Generating Access Permissions

IJAZ AHMEDadvised by : NESTOR CATANO

http://www3.uma.pt/ncatano/aeminium/GAP.html

GAP It takes a Java program and generates the likely access

permissions It implements a modular and static analysis of Java

programs. How it Works?

It extracts the read, write and alias information from a Java source code through AST

It generates a graph for every method that shows read, write and alias information

It traverses the graph and gathers likely information It works in two mode i.e. Read mode and Write mode

An implementation of the algorithm as an Eclipse plug-in is on way

http://www3.uma.pt/ncatano/aeminium/GAP.html

General Idea

http://www3.uma.pt/ncatano/aeminium/GAP.html

Notations, Terminology and Concepts Method Node

an abstraction to represent method local environment Context Node

an abstraction to represent external world/other references Reference Nodes

class fields, parameters, local variables Object Nodes

represent physical memory of objects Edges

Read Edge Write Edge Pointe Edge

http://www3.uma.pt/ncatano/aeminium/GAP.html

Some Rules

http://www3.uma.pt/ncatano/aeminium/GAP.html

General Idea To represent the read , write and alias information with edges Check the types of edges and number of Pointe’ edges to define

access PermissionsTypes of Rules

Graph Construction Rules Pre Access Permissions Rules (Graph Traversal) Post Access Permission Rules (Graph Traversal)

An Example- JAVA Programpublic class B{

int a;}

public class A {

B x,y,r; 

public Object method1(B z, B w ){x=w;Object t=x;y=t;z.a=15;System.print.out(x.a+w.a+t.a);return y;

}

}

http://www3.uma.pt/ncatano/aeminium/GAP.html

High Level Algorithm

Make the set Z = {Fields} U {Parameters}

Make the set M= object of set Z Make the set U = Z U M U { method,

Context}

Step 1- Create nodes for all items in set U

Step 2- Apply the Pointe-Rule for elements in set Z and set M

Step 3- Apply the rule Context-R if you are in mode R, otherwise apply rule

Context-RW if you are in mode RW.

public class A {B x,y,r;

 public Object method1(B z, B w ){

x=w;Object t=x;y=t;z.a=15;System.print.out(x.a+w.a+t.a);return y;}

Analysis of method1

http://www3.uma.pt/ncatano/aeminium/GAP.html

z w

x_object y_object w_objectz_object

xmethod1

context

y

High Level Algorithm

Make the set Z = {Fields} U {Parameters}

Make the set M= object of set Z Make the set U = Z U M U { method,

Context}

Step 1- Create nodes for all items in set U

Step 2- Apply the Pointe-Rule for elements in set Z and set M

Step 3- Apply the rule Context-R if you are in mode R, otherwise apply rule

Context-RW if you are in mode RW.

public class A {B x,y,r;

 public Object method1(B z, B w ){

x=w;Object t=x;y=t;z.a=15;System.print.out(x.a+w.a+t.a);return y;}

Analysis of method1

http://www3.uma.pt/ncatano/aeminium/GAP.html

z w

x_object y_object w_objectz_object

xmethod1

context

y

P P P P

High Level Algorithm

Make the set Z = {Fields} U {Parameters}

Make the set M= object of set Z Make the set U = Z U M U { method,

Context}

Step 1- Create nodes for all items in set U

Step 2- Apply the Pointe-Rule for elements in set Z and set M

Step 3- Apply the rule Context-R if you are in mode R, otherwise apply rule

Context-RW if you are in mode RW.

public class A {B x,y,r;

 public Object method1(B z, B w ){

x=w;Object t=x;y=t;z.a=15;System.print.out(x.a+w.a+t.a);return y;}

Analysis of method1

http://www3.uma.pt/ncatano/aeminium/GAP.html

z w

x_object y_object w_objectz_object

xmethod1

context

y

RRR R

P P P P

public class A {B x,y,r;

 

public Object method1(B z, B w ){x=w;Object t=x;y=t;z.a=15;System.print.out(x.a+w.a+t.a);return y;}

Analysis of method1

http://www3.uma.pt/ncatano/aeminium/GAP.html

z w

x_object y_object w_objectz_object

xmethod1

context

y

RRR R

P P P

High Level Algorithm

Step 4- For every statement s in the method body, apply a graph construction rule according to the syntax of s.

Step 5- Generate Pre-Permissions by applying Pre-Traversal Rules for items in set Z

Step 6- Generate Post-Permissions by applying Post-Traversal Rules for items in set Z.

P

public class A {B x,y,r;

 

public Object method1(B z, B w ){x=w;Object t=x;y=t;z.a=15;System.print.out(x.a+w.a+t.a);return y;}

Analysis of method1

http://www3.uma.pt/ncatano/aeminium/GAP.html

z w

x_object y_object w_objectz_object

xmethod1

context

y

RRR R

P P P

High Level Algorithm

Step 4- For every statement s in the method body, apply a graph construction rule according to the syntax of s.

Step 5- Generate Pre-Permissions by applying Pre-Traversal Rules for items in set Z

Step 6- Generate Post-Permissions by applying Post-Traversal Rules for items in set Z.

P

public class A {B x,y,r;

 

public Object method1(B z, B w ){x=w;Object t=x;y=t;z.a=15;System.print.out(x.a+w.a+t.a);return y;}

Analysis of method1

http://www3.uma.pt/ncatano/aeminium/GAP.html

z w

x_object y_object w_objectz_object

xmethod1

context

y

RRR R

P P P

High Level Algorithm

Step 4- For every statement s in the method body, apply a graph construction rule according to the syntax of s.

Step 5- Generate Pre-Permissions by applying Pre-Traversal Rules for items in set Z

Step 6- Generate Post-Permissions by applying Post-Traversal Rules for items in set Z.

P

public class A {B x,y,r;

 

public Object method1(B z, B w ){x=w;Object t=x;y=t;z.a=15;System.print.out(x.a+w.a+t.a);return y;}

Analysis of method1

http://www3.uma.pt/ncatano/aeminium/GAP.html

z w

x_object y_object w_objectz_object

xmethod1

context

y

RRR R

P P P

High Level Algorithm

Step 4- For every statement s in the method body, apply a graph construction rule according to the syntax of s.

Step 5- Generate Pre-Permissions by applying Pre-Traversal Rules for items in set Z

Step 6- Generate Post-Permissions by applying Post-Traversal Rules for items in set Z.

t

PP

public class A {B x,y,r;

 

public Object method1(B z, B w ){x=w;Object t=x;y=t;z.a=15;System.print.out(x.a+w.a+t.a);return y;}

Analysis of method1

http://www3.uma.pt/ncatano/aeminium/GAP.html

z w

x_object y_object w_objectz_object

xmethod1

context

y

RRR R

P P P

High Level Algorithm

Step 4- For every statement s in the method body, apply a graph construction rule according to the syntax of s.

Step 5- Generate Pre-Permissions by applying Pre-Traversal Rules for items in set Z

Step 6- Generate Post-Permissions by applying Post-Traversal Rules for items in set Z.

t

PP

public class A {B x,y,r;

 

public Object method1(B z, B w ){x=w;Object t=x;y=t;z.a=15;System.print.out(x.a+w.a+t.a);return y;}

Analysis of method1

http://www3.uma.pt/ncatano/aeminium/GAP.html

z w

x_object y_object w_objectz_object

xmethod1

context

y

RRR R

P P

High Level Algorithm

Step 4- For every statement s in the method body, apply a graph construction rule according to the syntax of s.

Step 5- Generate Pre-Permissions by applying Pre-Traversal Rules for items in set Z

Step 6- Generate Post-Permissions by applying Post-Traversal Rules for items in set Z.

t

PP

public class A {B x,y,r;

 

public Object method1(B z, B w ){x=w;Object t=x;y=t;z.a=15;System.print.out(x.a+w.a+t.a);return y;}

Analysis of method1

http://www3.uma.pt/ncatano/aeminium/GAP.html

z w

x_object y_object w_objectz_object

xmethod1

context

y

RRR R

P P

High Level Algorithm

Step 4- For every statement s in the method body, apply a graph construction rule according to the syntax of s.

Step 5- Generate Pre-Permissions by applying Pre-Traversal Rules for items in set Z

Step 6- Generate Post-Permissions by applying Post-Traversal Rules for items in set Z.

t

PP

public class A {B x,y,r;

 

public Object method1(B z, B w ){x=w;Object t=x;y=t;z.a=15;System.print.out(x.a+w.a+t.a);return y;}

Analysis of method1

http://www3.uma.pt/ncatano/aeminium/GAP.html

z w

x_object y_object w_objectz_object

xmethod1

context

y

RRR R

P P

High Level Algorithm

Step 4- For every statement s in the method body, apply a graph construction rule according to the syntax of s.

Step 5- Generate Pre-Permissions by applying Pre-Traversal Rules for items in set Z

Step 6- Generate Post-Permissions by applying Post-Traversal Rules for items in set Z.

t

P

w

P

public class A {B x,y,r;

 

public Object method1(B z, B w ){x=w;Object t=x;y=t;z.a=15;System.print.out(x.a+w.a+t.a);return y;}

Analysis of method1

http://www3.uma.pt/ncatano/aeminium/GAP.html

z w

x_object y_object w_objectz_object

xmethod1

context

y

RRR R

P P

High Level Algorithm

Step 4- For every statement s in the method body, apply a graph construction rule according to the syntax of s.

Step 5- Generate Pre-Permissions by applying Pre-Traversal Rules for items in set Z

Step 6- Generate Post-Permissions by applying Post-Traversal Rules for items in set Z.

t

P

w

P

High Level Algorithm

Step 4- For every statement s in the method body, apply a graph construction rule according to the syntax of s.

Step 5- Generate Pre-Permissions by applying Pre-Traversal Rules for items in set Z

Step 6- Generate Post-Permissions by applying Post-Traversal Rules for items in set Z.

public class A {B x,y,r;

 public Object method1(B z, B w ){

x=w;Object t=x;y=t;z.a=15;System.print.out(x.a+w.a+t.a);return y;}

Analysis of method1

http://www3.uma.pt/ncatano/aeminium/GAP.html

z w

x_object y_object w_objectz_object

xmethod1

context

y

RRR R

P P

t

P

w

R

P

public class A {B x,y,r;

 

public Object method1(B z, B w ){x=w;Object t=x;y=t;z.a=15;System.print.out(x.a+w.a+t.a);return y;}

High Level Algorithm

Step 4- For every statement s in the method body, apply a graph construction rule according to the syntax of s.

Step 5- Generate Pre-Permissions by applying Pre-Traversal Rules for items in set Z

Step 6- Generate Post-Permissions by applying Post-Traversal Rules for items in set Z.

Analysis of method1

http://www3.uma.pt/ncatano/aeminium/GAP.html

z w

x_object y_object w_objectz_object

xmethod1

context

y

RRR R

P P

t

P

w

R

P

public class A {B x,y,r;

full(x), full(y),full(z),Immutable(w)

public Object method1(B z, B w ){x=w;Object t=x;y=t;z.a=15;System.print.out(x.a+w.a+t.a);return y;}

High Level Algorithm

Step 4- For every statement s in the method body, apply a graph construction rule according to the syntax of s.

Step 5- Generate Pre-Permissions by applying Pre-Traversal Rules for items in set Z

Step 6- Generate Post-Permissions by applying Post-Traversal Rules for items in set Z.

Analysis of method1

http://www3.uma.pt/ncatano/aeminium/GAP.html

z w

x_object y_object w_objectz_object

xmethod1

context

y

RRR R

P P

t

P

w

R

P

High Level Algorithm

Step 4- For every statement s in the method body, apply a graph construction rule according to the syntax of s.

Step 5- Generate Pre-Permissions by applying Pre-Traversal Rules for items in set Z

Step 6- Generate Post-Permissions by applying Post-Traversal Rules for items in set Z.

public class A {B x,y,r;

full(x), full(y),full(z),Immutable(w)

public Object method1(B z, B w ){x=w;Object t=x;y=t;z.a=15;System.print.out(x.a+w.a+t.a);return y;}

Analysis of method1

http://www3.uma.pt/ncatano/aeminium/GAP.html

z w

x_object y_object w_objectz_object

xmethod1

context

y

RRR R

P P

t

P

w

R

P

High Level Algorithm

Step 4- For every statement s in the method body, apply a graph construction rule according to the syntax of s.

Step 5- Generate Pre-Permissions by applying Pre-Traversal Rules for items in set Z

Step 6- Generate Post-Permissions by applying Post-Traversal Rules for items in set Z.

public class A {B x,y,r;

full(x), full(y),full(z),Immutable(w) Immutable(x), Immutable(y)public Object method1(B z, B w ){

x=w;Object t=x;y=t;z.a=15;System.print.out(x.a+w.a+t.a);return y;}

Analysis of method1

http://www3.uma.pt/ncatano/aeminium/GAP.html

z w

x_object y_object w_objectz_object

xmethod1

context

y

RRR R

P P

t

P

w

R

P

Conclusion

http://www3.uma.pt/ncatano/aeminium/GAP.html

Present Status Can generate access permission for simple program Tested with some examples Under development

Future Work Parser require further iterations to parse complex program Mapping of GAP Specifications with Plural Syntax Planning to run GAP on the MTTS application as a bench

mark Integrate as an Eclipse plug-in with Plural

Link http://www3.uma.pt/ncatano/aeminium/GAP.html