peer-to-peer networks ... login{st} connection{pr} enable(st)loginpr pr. CLASSROOM login{st} ... process. ⢠A well-formed network is a parallel composition ( | ) of.
Types for Role-based Access Control of Dynamic Web Data Mariangiola Dezani-Ciancaglini 1 Silvia Ghilezan2 Svetlana Jakši´c 2 Jovanka Pantovi´c2 1 Università 2 University
di Torino
of Novi Sad
SVARM 2010, Edinburgh
Outline 1 Motivation
Related Work Access control - rXdπ-calculus 2 rXdπ-calculus
Syntax Semantics 3 Types
Types Safety
Outline 1 Motivation
Related Work Access control - rXdπ-calculus 2 rXdπ-calculus
Syntax Semantics 3 Types
Types Safety
Distributed systems - decentralised peer-to-peer networks • management of semi-structured and distributed data • processes with different roles have different access rights • different access policies in different locations • exchange between data and processes preserving access
control • dynamic changes of access rights •
One solution - typed models • control of access • control of movements rights
Distributed systems - decentralised peer-to-peer networks • management of semi-structured and distributed data • processes with different roles have different access rights • different access policies in different locations • exchange between data and processes preserving access
control • dynamic changes of access rights •
One solution - typed models • control of access • control of movements rights
Related work
• Xdπ calculus - extension of Active XML - Gardner, Maffeis • localised mobile processes • distributed, dynamic, semi-structured web data • Variety of type systems for dπ and related calculi • controlling the use of accesses and mobility of processes • Security types for Xdπ
Dezani, Ghilezan, Pantovic, Varacca, 2008 • partially ordered set (with bottom) as security levels • control of movements rights • network invariant and initial network
Distributed Network Location
l
T
R
Location A peer or a location is represented with data and a process.
Access Rights l
l
T
R
T
R
T
S
m
Security conditions • not all data is visible to all processes • different locations with different access policies
Roles
st v pr
CLASSROOM
PUBLIC
login{st}
login{st} enable(st)loginpr qpr
{pr}
connection
connection{st}
Roles
st v pr
CLASSROOM
PUBLIC
login{st}
login{st} enable(st)loginpr qpr
{pr}
connection
connection{st}
Roles
st v pr
CLASSROOM
PUBLIC
login{st}
login{st} enable(st)loginpr qpr
{pr}
connection
connection{st}
Outline 1 Motivation
Related Work Access control - rXdπ-calculus 2 rXdπ-calculus
Syntax Semantics 3 Types
Types Safety
Locations, Networks l
T
R
• Each location consists of data in a form of a tree and a
process • A well-formed network is a parallel composition ( | ) of
locations with different names. N ::= 0 | N | N | l[T k R] | (νc Tv )N
Data CLASSROOM
PUBLIC
login{st} a{st} p@λ
conncetion{pr} R
• R-scripted process • p-path • p@λ-pointer • run, read, change • dynamic changes of access rights
login{st} a{st} p@λ
connection{st} R
Data CLASSROOM
PUBLIC
login{st} a{st} p@λ
conncetion{pr} R
• R-scripted process • p-path • p@λ-pointer • run, read, change • dynamic changes of access rights
login{st} a{st} p@λ
connection{st} R
Processes π-calculus P
::=
0
the nil process
|
P|P
composition of processes
|
c¯Tv hv i
output value v on a channel c
|
c Tv (x).P
input parameterized by a variable x
|
!c Tv (x).P
replication of an input process
Processes π-calculus P
::=
0
the nil process
|
P|P
composition of processes
|
c¯Tv hv i
output value v on a channel c
|
c Tv (x).P
input parameterized by a variable x
|
!c Tv (x).P
replication of an input process
dπ-calculus P
::=
go λ.R
migrate to location λ, continue as R
Xdπ-calculus P
::=
runp
run command
|
readp (χ).P
read command
|
changep (χ, V ).P
change command
Processes rXdπ-calculus P
::=
enable(r )p .P
gives permission to the role r to access data on the path p
|
disable(r )p .P
removes the role r from roles that are allowed to access data on the path p
R
::=
Pqρ
single process with roles ρ
|
R|R
parallel composition of processes with roles
|
(νc Tv )R
restriction of channel name c
Interactions in the System
• Communication • Movement • Interaction with local data • Permission change
Reduction rules formally describe interactions in the system.
Interactions in the System
• Communication
l
Pqρ T Qqσ
• Movement • Interaction with local data • Permission change
Reduction rules formally describe interactions in the system.
Interactions in the System
• Communication • Movement
m
l
T
Pqρ
T Qqσ
• Interaction with local data • Permission change
Reduction rules formally describe interactions in the system.
Interactions in the System
• Communication • Movement • Interaction with local data
l
T
Pqρ
• Permission change
Reduction rules formally describe interactions in the system.
Interactions in the System
• Communication • Movement • Interaction with local data • Permission change
l
T
Pqρ
Reduction rules formally describe interactions in the system.
Operational Semantics - Example
aα
bβ
cρ
@d
@ bβ @l
γ
l (β)
(readaα (y (β) @x (σ,E,D) ).changeaα (y1 .go x.enable(r )y qρ )qρ
0
(σ,E,D)
@x1
, R)
Operational Semantics - Example
aα
bβ
cρ
@d
@ bβ @l
γ
l (β)
(readaα (y (β) @x (σ,E,D) ).changeaα (y1 .go x.enable(r )y qρ )qρ
0
(σ,E,D)
@x1
, R)
Operational Semantics - Example
aα
bβ
cρ
@d
@ bβ @l
γ
l (β)
(changeaα (y1
(σ,E,D)
@x1
, R).go l.enable(r )bβqρ )qρ
0
Operational Semantics - Example
aα
bβ
cρ
@d
@ bβ @l
γ
l (β)
(changeaα (y1
(σ,E,D)
@x1
0 β , R).go l.enable(r )b qρ )qρ
Operational Semantics - Example
aα
bβ
cρ
@d
@ R
γ
l (go l.enable(r )bβ qρ )qρ
0
Operational Semantics - Example
aα
bβ
cρ
@d
@ R
γ
l (go l.enable(r )bβ qρ )qρ
0
Operational Semantics - Example
aα
cρ
@ R
bβ
@d
γ
l enable(r )bβ qρ
Operational Semantics - Example
aα
cρ
@ R
bβ
@d
γ
l enable(r )bβ qρ
Operational Semantics - Example
aα
cρ
@ R
bβ
@d
γ∪{r }
l
Outline 1 Motivation
Related Work Access control - rXdπ-calculus 2 rXdπ-calculus
Syntax Semantics 3 Types
Types Safety
Type System Main goals • to control communication of values • to control migration and activation of processes • to control access to data and their modification
Location Policy (σ, E, D) • σ: set of minimal roles which can access data • E: policy for role enabling • D: policy for role disabling
Type System Main goals • to control communication of values • to control migration and activation of processes • to control access to data and their modification
Location Policy (σ, E, D) • σ: set of minimal roles which can access data • E: policy for role enabling • D: policy for role disabling
Type System - Example
st v sti v as v prof v dean where i ∈ I.
Type System - Example st v sti v as v prof v dean where i ∈ I. FACULTY : (σF , EF , DF ) σF = {sti } FACULTY
EF = ({prof}, as) DC = ({dean}, sti )
Type System - Example st v sti v as v prof v dean where i ∈ I. FACULTY : (σF , EF , DF ) σF = {sti }
EF = ({prof}, as) DC = ({dean}, sti )
FACULTY service{sti } records{pr}
mark
booklet{sti }
mark
Type System - Example st v sti v as v prof v dean where i ∈ I. FACULTY : (σF , EF , DF ) σF = {sti }
EF = ({prof}, as) DC = ({dean}, sti )
FACULTY service{sti } records{pr}
mark
booklet{sti }
mark
enable(as)servicepr qpr
Type System - Example st v sti v as v prof v dean where i ∈ I. FACULTY : (σF , EF , DF ) σF = {sti }
EF = ({prof}, as) DC = ({dean}, sti )
FACULTY service{sti } records{pr}
mark
booklet{sti }
mark
disable(sti )servicepr qdean
Type System - Example st v sti v as v prof v dean where i ∈ I. FACULTY : (σF , EF , DF ) σF = {sti }
EF = ({prof}, as) DC = ({dean}, sti )
FACULTY service{sti } records{pr}
mark
booklet{sti }
mark
enable(sti )servicepr qpr
Safety properties • (Subject reduction) If ` N : Net and N → N0 , then
` N0 : Net. • Properties of location policies and communication: P0 All trees and processes in a location agree with the location policy; P1 A process with roles can communicate only values with characteristic roles accessible to the process.
• Properties of migration between locations: P2 A process with roles can migrate to another location only if it is well typed for that location.
• Properties of access of processes to local data trees: P3 A process with roles looks for a path in the local tree only if the path is accessible to the process.
Safety properties
• Properties of manipulation of local data trees by
processes: P4 A script is activated in a location only if the corresponding process with roles can stay in that location; P5 A process with roles generated by a read command in a location can stay in that location; P6 A process with roles can erase a subtree of data only if it can access all data; P7 A tree built by a change command in a location can stay in that location; P8 A process with roles can add a role to an edge in the local tree only if this is allowed by the location policy; P9 A tree built by an enable command in a location can stay in that location; P10 A process with roles can erase a role from an edge in the local tree only if this is allowed by the location policy; P11 A tree built by a disable command in a location can stay in that location.
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