| Message ID | 1464015933-26891-3-git-send-email-dgdegra@tycho.nsa.gov (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, May 23, 2016 at 11:05:30AM -0400, Daniel De Graaf wrote: > This also renames the example users created by vm_role. Hey! Thank you for posting this. > > Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov> > --- > docs/misc/xsm-flask.txt | 34 +++++++++++----------- > tools/flask/policy/Makefile | 9 ++++-- > tools/flask/policy/modules/default_role.te | 5 ---- > tools/flask/policy/modules/modules.conf | 10 ++++++- > .../{policy/constraints => modules/vm_role.cons} | 6 ++-- > tools/flask/policy/modules/vm_role.te | 16 ++++++++++ > tools/flask/policy/modules/xen.te | 9 ++++-- > tools/flask/policy/policy/support/misc_macros.spt | 6 ++-- > tools/flask/policy/policy/users | 12 +------- > 9 files changed, 63 insertions(+), 44 deletions(-) > rename tools/flask/policy/{policy/constraints => modules/vm_role.cons} (78%) > create mode 100644 tools/flask/policy/modules/vm_role.te > > diff --git a/docs/misc/xsm-flask.txt b/docs/misc/xsm-flask.txt > index d3015ca..2f42585 100644 > --- a/docs/misc/xsm-flask.txt > +++ b/docs/misc/xsm-flask.txt > @@ -147,9 +147,11 @@ it relies on the SELinux compiler "checkpolicy"; run > make -C tools/flask/policy > > to compile the example policy included with Xen. The policy is generated from > -definition files under this directory. When creating or modifying security > -policy, most modifications will be made to the xen type enforcement (.te) file > -tools/flask/policy/policy/modules/xen/xen.te or the macro definitions in xen.if. > +definition files under this directory. Most changes to security policy will > +involve creating or modifying modules found in tools/flask/policy/modules/. The > +modules.conf file there defines what modules are enabled and has short > +descriptions of each module. > + > The XSM policy file needs to be copied to /boot and loaded as a module by grub. > The exact position of the module does not matter as long as it is after the Xen > kernel; it is normally placed either just above the dom0 kernel or at the end. > @@ -210,17 +212,16 @@ Type transitions are also used to compute the labels of event channels. > Users and roles > --------------- > > -Users are defined in tools/flask/policy/policy/users. The example policy defines > -two users (customer_1 and customer_2) in addition to the system user system_u. > -Users are visible in the labels of domains and associated objects (event > -channels); in the example policy, "customer_1:vm_r:domU_t" is a valid label for > -the customer_1 user. > +The default user and role used for domains is system_u and system_r. Users are > +visible in the labels of domains and associated objects (event channels); when > +the vm_role module is enabled, "user_1:vm_r:domU_t" is a valid label for a > +domain created by the user_1 user. > > -Access control rules involving users and roles are defined in the policy > -constraints file (tools/flask/policy/policy/constraints). The example policy > -provides constraints that prevent different users from communicating using > -grants or event channels, while still allowing communication with the system_u > -user where dom0 resides. > +Access control rules involving users and roles are defined in a module's > +constraints file (for example, vm_rule.cons). The vm_role module defines one > +role (vm_r) and three users (user_1 .. user_3), along with constraints that > +prevent different users from communicating using grants or event channels, while > +still allowing communication with the system_u user where dom0 resides. > > Resource Policy > --------------- > @@ -268,10 +269,9 @@ declare_domain and create_domain interfaces: > Existing SELinux tools such as audit2allow can be applied to these denials, e.g. > xl dmesg | audit2allow > > -The generated allow rules can then be fed back into the policy by > -adding them to xen.te, although manual review is advised and will > -often lead to adding parameterized rules to the interfaces in xen.if > -to address the general case. > +The generated allow rules can then be fed back into the policy by adding them to > +a module, although manual review is advised and will often lead to adding > +parameterized rules to the interfaces in xen.if to address the general case. > > > Device Labeling in Policy > diff --git a/tools/flask/policy/Makefile b/tools/flask/policy/Makefile > index b2c2d06..693eb10 100644 > --- a/tools/flask/policy/Makefile > +++ b/tools/flask/policy/Makefile > @@ -54,7 +54,6 @@ AVS += $(POLDIR)/access_vectors > M4SUPPORT := $(wildcard $(POLDIR)/support/*.spt) > MLSSUPPORT := $(POLDIR)/mls > USERS := $(POLDIR)/users > -CONSTRAINTS := $(POLDIR)/constraints > ISID_DEFS := $(POLDIR)/initial_sids > DEV_OCONS := $(POLDIR)/device_contexts > > @@ -90,8 +89,12 @@ MODENABLED := on > # extract settings from modules.conf > ENABLED_LIST := $(shell awk '/^[ \t]*[a-z]/{ if ($$3 == "$(MODENABLED)") print $$1 }' $(MOD_CONF) 2> /dev/null) > > +# Modules must provide a .te file, although it could be empty > ALL_MODULES := $(foreach mod,$(ENABLED_LIST),$(MODDIR)/$(mod).te) > + > +# Modules may also provide interfaces and constraint definitions > ALL_INTERFACES := $(wildcard $(ALL_MODULES:.te=.if)) > +ALL_CONSTRAINTS := $(wildcard $(ALL_MODULES:.te=.cons)) > > # The order of these files is important > POLICY_SECTIONS := $(SECCLASS) $(ISID_DECLS) $(AVS) > @@ -99,7 +102,9 @@ POLICY_SECTIONS += $(M4SUPPORT) $(MLSSUPPORT) > POLICY_SECTIONS += $(ALL_INTERFACES) > POLICY_SECTIONS += $(GLOBALTUN) > POLICY_SECTIONS += $(ALL_MODULES) > -POLICY_SECTIONS += $(USERS) $(CONSTRAINTS) $(ISID_DEFS) $(DEV_OCONS) > +POLICY_SECTIONS += $(USERS) > +POLICY_SECTIONS += $(ALL_CONSTRAINTS) > +POLICY_SECTIONS += $(ISID_DEFS) $(DEV_OCONS) > > all: $(POLICY_FILENAME) > > diff --git a/tools/flask/policy/modules/default_role.te b/tools/flask/policy/modules/default_role.te > index 74f870f..3018540 100644 > --- a/tools/flask/policy/modules/default_role.te > +++ b/tools/flask/policy/modules/default_role.te > @@ -1,8 +1,3 @@ > # Allow all domains to use system_r so that systems that are not using the > # user/role separation feature will work properly. > role system_r types domain_type; > - > -# The vm role is used as part of user separation. Allow all domain types to use > -# this role except dom0. > -role vm_r; > -role vm_r types { domain_type -dom0_t }; > diff --git a/tools/flask/policy/modules/modules.conf b/tools/flask/policy/modules/modules.conf > index 5a1d905..2dfc011 100644 > --- a/tools/flask/policy/modules/modules.conf > +++ b/tools/flask/policy/modules/modules.conf > @@ -33,5 +33,13 @@ nomigrate = on > # Example device policy. Also see policy/device_contexts. > nic_dev = on > > -# Example roles. Also see policy/users. > +# Allow all domains to use system_u:system_r: instead of requiring explicit > +# roles. This is not required for dom0_t, domU_t, and dm_dom_t. > default_role = on > + > +# Example users, roles, and constraints for user-based separation. > +# > +# The three users defined here can set up grant/event channel communication > +# (vchan, device frontend/backend) between their own VMs, but cannot set up a > +# channel to a VM under a different user. > +vm_role = on > diff --git a/tools/flask/policy/policy/constraints b/tools/flask/policy/modules/vm_role.cons > similarity index 78% > rename from tools/flask/policy/policy/constraints > rename to tools/flask/policy/modules/vm_role.cons > index 765ed4d..3847ec1 100644 > --- a/tools/flask/policy/policy/constraints > +++ b/tools/flask/policy/modules/vm_role.cons > @@ -1,6 +1,5 @@ > - > # > -# Define the constraints > +# Constraints are defined by: > # > # constrain class_set perm_set expression ; > # > @@ -25,8 +24,9 @@ > # name_list : name | name_list name > # > > -# Prevent event channels and grants between different customers > > +# Prevent event channels and grants between different users. This could be > +# further limited to only restricting those domains using the vm_r role. > constrain event bind ( > u1 == system_u or > u2 == system_u or So right up to here I followed it. But for later part I am afraid I need to study the policy language to grok it.
diff --git a/docs/misc/xsm-flask.txt b/docs/misc/xsm-flask.txt index d3015ca..2f42585 100644 --- a/docs/misc/xsm-flask.txt +++ b/docs/misc/xsm-flask.txt @@ -147,9 +147,11 @@ it relies on the SELinux compiler "checkpolicy"; run make -C tools/flask/policy to compile the example policy included with Xen. The policy is generated from -definition files under this directory. When creating or modifying security -policy, most modifications will be made to the xen type enforcement (.te) file -tools/flask/policy/policy/modules/xen/xen.te or the macro definitions in xen.if. +definition files under this directory. Most changes to security policy will +involve creating or modifying modules found in tools/flask/policy/modules/. The +modules.conf file there defines what modules are enabled and has short +descriptions of each module. + The XSM policy file needs to be copied to /boot and loaded as a module by grub. The exact position of the module does not matter as long as it is after the Xen kernel; it is normally placed either just above the dom0 kernel or at the end. @@ -210,17 +212,16 @@ Type transitions are also used to compute the labels of event channels. Users and roles --------------- -Users are defined in tools/flask/policy/policy/users. The example policy defines -two users (customer_1 and customer_2) in addition to the system user system_u. -Users are visible in the labels of domains and associated objects (event -channels); in the example policy, "customer_1:vm_r:domU_t" is a valid label for -the customer_1 user. +The default user and role used for domains is system_u and system_r. Users are +visible in the labels of domains and associated objects (event channels); when +the vm_role module is enabled, "user_1:vm_r:domU_t" is a valid label for a +domain created by the user_1 user. -Access control rules involving users and roles are defined in the policy -constraints file (tools/flask/policy/policy/constraints). The example policy -provides constraints that prevent different users from communicating using -grants or event channels, while still allowing communication with the system_u -user where dom0 resides. +Access control rules involving users and roles are defined in a module's +constraints file (for example, vm_rule.cons). The vm_role module defines one +role (vm_r) and three users (user_1 .. user_3), along with constraints that +prevent different users from communicating using grants or event channels, while +still allowing communication with the system_u user where dom0 resides. Resource Policy --------------- @@ -268,10 +269,9 @@ declare_domain and create_domain interfaces: Existing SELinux tools such as audit2allow can be applied to these denials, e.g. xl dmesg | audit2allow -The generated allow rules can then be fed back into the policy by -adding them to xen.te, although manual review is advised and will -often lead to adding parameterized rules to the interfaces in xen.if -to address the general case. +The generated allow rules can then be fed back into the policy by adding them to +a module, although manual review is advised and will often lead to adding +parameterized rules to the interfaces in xen.if to address the general case. Device Labeling in Policy diff --git a/tools/flask/policy/Makefile b/tools/flask/policy/Makefile index b2c2d06..693eb10 100644 --- a/tools/flask/policy/Makefile +++ b/tools/flask/policy/Makefile @@ -54,7 +54,6 @@ AVS += $(POLDIR)/access_vectors M4SUPPORT := $(wildcard $(POLDIR)/support/*.spt) MLSSUPPORT := $(POLDIR)/mls USERS := $(POLDIR)/users -CONSTRAINTS := $(POLDIR)/constraints ISID_DEFS := $(POLDIR)/initial_sids DEV_OCONS := $(POLDIR)/device_contexts @@ -90,8 +89,12 @@ MODENABLED := on # extract settings from modules.conf ENABLED_LIST := $(shell awk '/^[ \t]*[a-z]/{ if ($$3 == "$(MODENABLED)") print $$1 }' $(MOD_CONF) 2> /dev/null) +# Modules must provide a .te file, although it could be empty ALL_MODULES := $(foreach mod,$(ENABLED_LIST),$(MODDIR)/$(mod).te) + +# Modules may also provide interfaces and constraint definitions ALL_INTERFACES := $(wildcard $(ALL_MODULES:.te=.if)) +ALL_CONSTRAINTS := $(wildcard $(ALL_MODULES:.te=.cons)) # The order of these files is important POLICY_SECTIONS := $(SECCLASS) $(ISID_DECLS) $(AVS) @@ -99,7 +102,9 @@ POLICY_SECTIONS += $(M4SUPPORT) $(MLSSUPPORT) POLICY_SECTIONS += $(ALL_INTERFACES) POLICY_SECTIONS += $(GLOBALTUN) POLICY_SECTIONS += $(ALL_MODULES) -POLICY_SECTIONS += $(USERS) $(CONSTRAINTS) $(ISID_DEFS) $(DEV_OCONS) +POLICY_SECTIONS += $(USERS) +POLICY_SECTIONS += $(ALL_CONSTRAINTS) +POLICY_SECTIONS += $(ISID_DEFS) $(DEV_OCONS) all: $(POLICY_FILENAME) diff --git a/tools/flask/policy/modules/default_role.te b/tools/flask/policy/modules/default_role.te index 74f870f..3018540 100644 --- a/tools/flask/policy/modules/default_role.te +++ b/tools/flask/policy/modules/default_role.te @@ -1,8 +1,3 @@ # Allow all domains to use system_r so that systems that are not using the # user/role separation feature will work properly. role system_r types domain_type; - -# The vm role is used as part of user separation. Allow all domain types to use -# this role except dom0. -role vm_r; -role vm_r types { domain_type -dom0_t }; diff --git a/tools/flask/policy/modules/modules.conf b/tools/flask/policy/modules/modules.conf index 5a1d905..2dfc011 100644 --- a/tools/flask/policy/modules/modules.conf +++ b/tools/flask/policy/modules/modules.conf @@ -33,5 +33,13 @@ nomigrate = on # Example device policy. Also see policy/device_contexts. nic_dev = on -# Example roles. Also see policy/users. +# Allow all domains to use system_u:system_r: instead of requiring explicit +# roles. This is not required for dom0_t, domU_t, and dm_dom_t. default_role = on + +# Example users, roles, and constraints for user-based separation. +# +# The three users defined here can set up grant/event channel communication +# (vchan, device frontend/backend) between their own VMs, but cannot set up a +# channel to a VM under a different user. +vm_role = on diff --git a/tools/flask/policy/policy/constraints b/tools/flask/policy/modules/vm_role.cons similarity index 78% rename from tools/flask/policy/policy/constraints rename to tools/flask/policy/modules/vm_role.cons index 765ed4d..3847ec1 100644 --- a/tools/flask/policy/policy/constraints +++ b/tools/flask/policy/modules/vm_role.cons @@ -1,6 +1,5 @@ - # -# Define the constraints +# Constraints are defined by: # # constrain class_set perm_set expression ; # @@ -25,8 +24,9 @@ # name_list : name | name_list name # -# Prevent event channels and grants between different customers +# Prevent event channels and grants between different users. This could be +# further limited to only restricting those domains using the vm_r role. constrain event bind ( u1 == system_u or u2 == system_u or diff --git a/tools/flask/policy/modules/vm_role.te b/tools/flask/policy/modules/vm_role.te new file mode 100644 index 0000000..f816de1 --- /dev/null +++ b/tools/flask/policy/modules/vm_role.te @@ -0,0 +1,16 @@ +# The vm role is used as part of user separation. Allow all domain types to use +# this role except dom0. +role vm_r; +role vm_r types { domain_type -dom0_t }; + +# Define some users that must use this role (full type "user_1:vm_r:domU_t"). +gen_user(user_1,, vm_r, s0, s0) +gen_user(user_2,, vm_r, s0, s0) +gen_user(user_3,, vm_r, s0, s0) + +# Alternate: define and use a macro to generate 1000 users +define(`def_vm_users',`gen_user(user_$1,, vm_r, s0, s0) +ifelse(`$1',`$2',,`def_vm_users(incr($1),$2)')dnl +') + +# def_vm_users(0,999) diff --git a/tools/flask/policy/modules/xen.te b/tools/flask/policy/modules/xen.te index f374dc5..b52edc2 100644 --- a/tools/flask/policy/modules/xen.te +++ b/tools/flask/policy/modules/xen.te @@ -71,14 +71,17 @@ neverallow * ~event_type:event { create send status }; ################################################################################ # -# Roles +# Users and Roles # ################################################################################ # The object role (object_r) is used for devices, resources, and event channels; # it does not need to be defined here and should not be used for domains. -# The system role is used for utility domains and pseudo-domains. If roles are -# not being used for separation, all domains can use the system role. +# The system user and role are used for utility domains and pseudo-domains. In +# systems where users and roles are not being used for separation, all domains +# can use the system user and role. +gen_user(system_u,, system_r, s0, s0 - mls_systemhigh) + role system_r; role system_r types { xen_type dom0_t }; diff --git a/tools/flask/policy/policy/support/misc_macros.spt b/tools/flask/policy/policy/support/misc_macros.spt index 2b27955..344f5c4 100644 --- a/tools/flask/policy/policy/support/misc_macros.spt +++ b/tools/flask/policy/policy/support/misc_macros.spt @@ -49,9 +49,11 @@ define(`refpolicyerr',`errprint(__file__:__line__: Error: `$1'__endline__)') # # gen_user(username, prefix, role_set, mls_defaultlevel, mls_range) # -define(`gen_user',`dnl +define(`gen_user',`define(`gen_all_users', gen_all_users `dnl user $1 roles { $3 }`'ifdef(`enable_mls', ` level $4 range $5')`'; -') +')') + +define(`gen_all_users',`') ######################################## # diff --git a/tools/flask/policy/policy/users b/tools/flask/policy/policy/users index 35ed8a9..af6acbd 100644 --- a/tools/flask/policy/policy/users +++ b/tools/flask/policy/policy/users @@ -1,11 +1 @@ -################################## -# -# System User configuration. -# - -# system_u is the user identity for system domains and objects -gen_user(system_u,, system_r, s0, s0 - mls_systemhigh) - -# Other users are defined using the vm role -gen_user(customer_1,, vm_r, s0, s0) -gen_user(customer_2,, vm_r, s0, s0) +gen_all_users()
This also renames the example users created by vm_role. Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov> --- docs/misc/xsm-flask.txt | 34 +++++++++++----------- tools/flask/policy/Makefile | 9 ++++-- tools/flask/policy/modules/default_role.te | 5 ---- tools/flask/policy/modules/modules.conf | 10 ++++++- .../{policy/constraints => modules/vm_role.cons} | 6 ++-- tools/flask/policy/modules/vm_role.te | 16 ++++++++++ tools/flask/policy/modules/xen.te | 9 ++++-- tools/flask/policy/policy/support/misc_macros.spt | 6 ++-- tools/flask/policy/policy/users | 12 +------- 9 files changed, 63 insertions(+), 44 deletions(-) rename tools/flask/policy/{policy/constraints => modules/vm_role.cons} (78%) create mode 100644 tools/flask/policy/modules/vm_role.te