On Thu, Jul 21, 2022 at 11:11 AM Christian Göttsche <cgzones@xxxxxxxxxxxxxx> wrote: > > Add a new compile-time constraint, similar to neverallow, which enables > to specify two or more type attributes to be mutual exclusive. This > means no type can be associated with more than one of them. > > The constraints are stored as a linked-list in the policy for modular > policies, by a new modular policy version, and are discarded in kernel > policies, not needing any kernel support. > > Some Reference Policy examples: > > unpriv_userdomain, admindomain: > > <no violations> > > client_packet_type, server_packet_type: > > <no violations> > > auth_file_type, non_auth_file_type: > > <no violations> > > pseudofs, xattrfs, noxattrfs: > > <no violations> > > reserved_port_type, unreserved_port_type: > > <no violations> > > security_file_type, non_security_file_type: > > libsepol.check_segregate_attributes: Segregate Attributes violation, type dnssec_t associated with attributes security_file_type and non_security_file_type > > ibendport_type, packet_type, sysctl_type, device_node, ibpkey_type, > sysfs_types, domain, boolean_type, netif_type, file_type, node_type, > proc_type, port_type: > > libsepol.check_segregate_attributes: Segregate Attributes violation, type sysctl_fs_t associated with attributes sysctl_type and file_type > libsepol.check_segregate_attributes: Segregate Attributes violation, type sysctl_t associated with attributes sysctl_type and file_type > libsepol.check_segregate_attributes: Segregate Attributes violation, type virt_content_t associated with attributes device_node and file_type > libsepol.check_segregate_attributes: Segregate Attributes violation, type initrc_devpts_t associated with attributes device_node and file_type > libsepol.check_segregate_attributes: Segregate Attributes violation, type qemu_image_t associated with attributes device_node and file_type > libsepol.check_segregate_attributes: Segregate Attributes violation, type user_devpts_t associated with attributes device_node and file_type > libsepol.check_segregate_attributes: Segregate Attributes violation, type cardmgr_dev_t associated with attributes device_node and file_type > libsepol.check_segregate_attributes: Segregate Attributes violation, type bootloader_tmp_t associated with attributes device_node and file_type > libsepol.check_segregate_attributes: Segregate Attributes violation, type xen_image_t associated with attributes device_node and file_type > libsepol.check_segregate_attributes: Segregate Attributes violation, type svirt_prot_exec_image_t associated with attributes device_node and file_type > libsepol.check_segregate_attributes: Segregate Attributes violation, type xen_devpts_t associated with attributes device_node and file_type > libsepol.check_segregate_attributes: Segregate Attributes violation, type svirt_image_t associated with attributes device_node and file_type > libsepol.check_segregate_attributes: Segregate Attributes violation, type virt_image_t associated with attributes device_node and file_type > libsepol.check_segregate_attributes: Segregate Attributes violation, type container_file_t associated with attributes device_node and file_type > libsepol.check_segregate_attributes: Segregate Attributes violation, type cpu_online_t associated with attributes sysfs_types and file_type > libsepol.check_segregate_attributes: Segregate Attributes violation, type sysfs_t associated with attributes sysfs_types and file_type > libsepol.check_segregate_attributes: Segregate Attributes violation, type dockerc_t associated with attributes domain and file_type > libsepol.check_segregate_attributes: Segregate Attributes violation, type proc_t associated with attributes file_type and proc_type > libsepol.check_segregate_attributes: Segregate Attributes violation, type proc_xen_t associated with attributes file_type and proc_type > > libsepol.check_assertions: 20 Segregate Attributes failures occurred > > Closes: https://github.com/SELinuxProject/selinux/issues/42 > > Signed-off-by: Christian Göttsche <cgzones@xxxxxxxxxxxxxx> > --- > v3: > - drop source location information: > this information was already lost for binary modular policies and > CIL policies; also typeattribute statements have none and the few > segregate_attributes statements can be easily grepped > - misc renaming > v2: > rebase onto _after suffix change I am not completely sold on this for a couple of reasons. 1) Neverallow rules express actual security goals. 2) Should we really keep adding more to the modular policy and policy.conf languages? 3) This can already be tested in CIL (but not as cleanly) (typeattribute disjoint_types) (typeattributeset disjoint_types (and attr1 attr2)) (allow disjoint_types self (process (transition))) (neverallow disjoint_types self (process (transition))) I would prefer "disjoint" to "segegrate" as well. Thanks, Jim > --- > libsepol/include/sepol/policydb/policydb.h | 15 ++++- > libsepol/src/assertion.c | 57 +++++++++++++--- > libsepol/src/expand.c | 45 ++++++++++++- > libsepol/src/kernel_to_conf.c | 38 ++++++++++- > libsepol/src/link.c | 44 +++++++++++++ > libsepol/src/policydb.c | 76 ++++++++++++++++++++++ > libsepol/src/policydb_validate.c | 29 +++++++++ > libsepol/src/write.c | 34 +++++++++- > 8 files changed, 325 insertions(+), 13 deletions(-) > > diff --git a/libsepol/include/sepol/policydb/policydb.h b/libsepol/include/sepol/policydb/policydb.h > index de0068a6..d62d030c 100644 > --- a/libsepol/include/sepol/policydb/policydb.h > +++ b/libsepol/include/sepol/policydb/policydb.h > @@ -192,6 +192,12 @@ typedef struct type_datum { > uint32_t bounds; /* bounds type, if exist */ > } type_datum_t; > > +/* Mutual exclusive attributes */ > +typedef struct segregate_attributes_rule { > + ebitmap_t attrs; /* mutual exclusive attributes */ > + struct segregate_attributes_rule *next; > +} segregate_attributes_rule_t; > + > /* > * Properties of type_datum > * available on the policy version >= (MOD_)POLICYDB_VERSION_BOUNDARY > @@ -605,6 +611,10 @@ typedef struct policydb { > bitmaps. Someday the 0 bit may be used for global permissive */ > ebitmap_t permissive_map; > > + /* mutual exclusive attributes (not preserved in kernel policy). > + stored as linked list */ > + segregate_attributes_rule_t *segregate_attributes; > + > unsigned policyvers; > > unsigned handle_unknown; > @@ -696,6 +706,8 @@ extern void level_datum_init(level_datum_t * x); > extern void level_datum_destroy(level_datum_t * x); > extern void cat_datum_init(cat_datum_t * x); > extern void cat_datum_destroy(cat_datum_t * x); > +extern void segregate_attributes_rule_init(segregate_attributes_rule_t * x); > +extern void segregate_attributes_rule_destroy(segregate_attributes_rule_t * x); > extern int check_assertion(policydb_t *p, avrule_t *avrule); > extern int check_assertions(sepol_handle_t * handle, > policydb_t * p, avrule_t * avrules); > @@ -783,9 +795,10 @@ extern int policydb_set_target_platform(policydb_t *p, int platform); > #define MOD_POLICYDB_VERSION_INFINIBAND 19 > #define MOD_POLICYDB_VERSION_GLBLUB 20 > #define MOD_POLICYDB_VERSION_SELF_TYPETRANS 21 > +#define MOD_POLICYDB_VERSION_SEGREGATE_ATTRIBUTES 22 > > #define MOD_POLICYDB_VERSION_MIN MOD_POLICYDB_VERSION_BASE > -#define MOD_POLICYDB_VERSION_MAX MOD_POLICYDB_VERSION_SELF_TYPETRANS > +#define MOD_POLICYDB_VERSION_MAX MOD_POLICYDB_VERSION_SEGREGATE_ATTRIBUTES > > #define POLICYDB_CONFIG_MLS 1 > > diff --git a/libsepol/src/assertion.c b/libsepol/src/assertion.c > index 161874c3..a6dda570 100644 > --- a/libsepol/src/assertion.c > +++ b/libsepol/src/assertion.c > @@ -36,7 +36,7 @@ struct avtab_match_args { > unsigned long errors; > }; > > -static const char* policy_name(policydb_t *p) { > +static const char* policy_name(const policydb_t *p) { > const char *policy_file = "policy.conf"; > if (p->name) { > policy_file = p->name; > @@ -535,6 +535,44 @@ int check_assertion(policydb_t *p, avrule_t *avrule) > return rc; > } > > +static int check_segregate_attributes(sepol_handle_t *handle, const policydb_t *p) > +{ > + const segregate_attributes_rule_t *sattr; > + int errors = 0, rc; > + > + for (sattr = p->segregate_attributes; sattr; sattr = sattr->next) { > + ebitmap_node_t *first_node; > + unsigned int first_bit; > + > + ebitmap_for_each_positive_bit(&sattr->attrs, first_node, first_bit) { > + ebitmap_node_t *second_node; > + unsigned int second_bit; > + > + ebitmap_for_each_positive_bit_after(&sattr->attrs, second_node, second_bit, first_node, first_bit) { > + ebitmap_t attr_union; > + ebitmap_node_t *type_node; > + unsigned int type_bit; > + > + rc = ebitmap_and(&attr_union, &p->attr_type_map[first_bit], &p->attr_type_map[second_bit]); > + if (rc < 0) > + return rc; > + > + ebitmap_for_each_positive_bit(&attr_union, type_node, type_bit) { > + ERR(handle, "Segregate Attributes violation, type %s associated with attributes %s and %s", > + p->p_type_val_to_name[type_bit], > + p->p_type_val_to_name[first_bit], > + p->p_type_val_to_name[second_bit]); > + errors++; > + } > + > + ebitmap_destroy(&attr_union); > + } > + } > + } > + > + return errors; > +} > + > int check_assertions(sepol_handle_t * handle, policydb_t * p, > avrule_t * avrules) > { > @@ -542,13 +580,6 @@ int check_assertions(sepol_handle_t * handle, policydb_t * p, > avrule_t *a; > unsigned long errors = 0; > > - if (!avrules) { > - /* Since assertions are stored in avrules, if it is NULL > - there won't be any to check. This also prevents an invalid > - free if the avtabs are never initialized */ > - return 0; > - } > - > for (a = avrules; a != NULL; a = a->next) { > if (!(a->specified & (AVRULE_NEVERALLOW | AVRULE_XPERMS_NEVERALLOW))) > continue; > @@ -570,5 +601,15 @@ int check_assertions(sepol_handle_t * handle, policydb_t * p, > if (errors) > ERR(handle, "%lu neverallow failures occurred", errors); > > + rc = check_segregate_attributes(handle, p); > + if (rc < 0) { > + ERR(handle, "Error occurred while checking Segregate Attributes"); > + return -1; > + } > + if (rc) { > + ERR(handle, "%d Segregate Attributes failures occurred", rc); > + errors += rc; > + } > + > return errors ? -1 : 0; > } > diff --git a/libsepol/src/expand.c b/libsepol/src/expand.c > index 8d19850e..6f52d1ff 100644 > --- a/libsepol/src/expand.c > +++ b/libsepol/src/expand.c > @@ -56,7 +56,7 @@ static void expand_state_init(expand_state_t * state) > memset(state, 0, sizeof(expand_state_t)); > } > > -static int map_ebitmap(ebitmap_t * src, ebitmap_t * dst, uint32_t * map) > +static int map_ebitmap(const ebitmap_t * src, ebitmap_t * dst, const uint32_t * map) > { > unsigned int i; > ebitmap_node_t *tnode; > @@ -2341,6 +2341,45 @@ static int genfs_copy(expand_state_t * state) > return 0; > } > > +static int segregate_attributes_copy(expand_state_t *state) > +{ > + const segregate_attributes_rule_t *old; > + segregate_attributes_rule_t *list = NULL; > + > + for (old = state->base->segregate_attributes; old; old = old->next) { > + segregate_attributes_rule_t *new; > + > + new = malloc(sizeof(segregate_attributes_rule_t)); > + if (!new) { > + ERR(state->handle, "Out of memory!"); > + return -1; > + } > + > + segregate_attributes_rule_init(new); > + > + if (map_ebitmap(&old->attrs, &new->attrs, state->typemap)) { > + ERR(state->handle, "out of memory"); > + ebitmap_destroy(&new->attrs); > + free(new); > + return -1; > + } > + > + if (list) > + list->next = new; > + else { > + if (state->out->segregate_attributes) { > + segregate_attributes_rule_t *s; > + for (s = state->out->segregate_attributes; s->next; s = s->next) {} > + s->next = new; > + } else > + state->out->segregate_attributes = new; > + } > + list = new; > + } > + > + return 0; > +} > + > static int type_attr_map(hashtab_key_t key > __attribute__ ((unused)), hashtab_datum_t datum, > void *ptr) > @@ -3173,6 +3212,10 @@ int expand_module(sepol_handle_t * handle, > if (genfs_copy(&state)) > goto cleanup; > > + /* copy segregate attributes */ > + if (segregate_attributes_copy(&state)) > + goto cleanup; > + > /* Build the type<->attribute maps and remove attributes. */ > state.out->attr_type_map = calloc(state.out->p_types.nprim, > sizeof(ebitmap_t)); > diff --git a/libsepol/src/kernel_to_conf.c b/libsepol/src/kernel_to_conf.c > index 63dffd9b..f119d572 100644 > --- a/libsepol/src/kernel_to_conf.c > +++ b/libsepol/src/kernel_to_conf.c > @@ -1839,6 +1839,33 @@ exit: > return rc; > } > > +static int write_segregate_attributes_to_conf(FILE *out, const struct policydb *pdb) > +{ > + const segregate_attributes_rule_t *sattr; > + > + for (sattr = pdb->segregate_attributes; sattr; sattr = sattr->next) { > + struct ebitmap_node *node; > + unsigned int bit; > + int first = 1; > + > + sepol_printf(out, "segregate_attributes "); > + > + ebitmap_for_each_positive_bit(&sattr->attrs, node, bit) { > + if (first) { > + first = 0; > + } else { > + sepol_printf(out, ", "); > + } > + > + sepol_printf(out, "%s", pdb->p_type_val_to_name[bit - 1]); > + } > + > + sepol_printf(out, ";\n"); > + } > + > + return 0; > +} > + > struct map_filename_trans_args { > struct policydb *pdb; > struct strs *strs; > @@ -3200,7 +3227,16 @@ int sepol_kernel_policydb_to_conf(FILE *out, struct policydb *pdb) > if (rc != 0) { > goto exit; > } > - write_filename_trans_rules_to_conf(out, pdb); > + > + rc = write_segregate_attributes_to_conf(out, pdb); > + if (rc != 0) { > + goto exit; > + } > + > + rc = write_filename_trans_rules_to_conf(out, pdb); > + if (rc != 0) { > + goto exit; > + } > > if (pdb->mls) { > rc = write_range_trans_rules_to_conf(out, pdb); > diff --git a/libsepol/src/link.c b/libsepol/src/link.c > index cbe4cea4..1650a9c0 100644 > --- a/libsepol/src/link.c > +++ b/libsepol/src/link.c > @@ -1857,6 +1857,45 @@ static int scope_copy_callback(hashtab_key_t key, hashtab_datum_t datum, > return -1; > } > > +static int copy_segregate_attributes(link_state_t * state, const policy_module_t *module) > +{ > + const segregate_attributes_rule_t *src_sattr; > + segregate_attributes_rule_t *list = NULL; > + > + for (src_sattr = module->policy->segregate_attributes; src_sattr; src_sattr = src_sattr->next) { > + segregate_attributes_rule_t *new_sattr; > + > + new_sattr = malloc(sizeof(segregate_attributes_rule_t)); > + if (!new_sattr) { > + ERR(state->handle, "Out of memory!"); > + return -1; > + } > + > + segregate_attributes_rule_init(new_sattr); > + > + if (ebitmap_convert(&src_sattr->attrs, &new_sattr->attrs, module->map[SYM_TYPES])) { > + ebitmap_destroy(&new_sattr->attrs); > + free(new_sattr); > + ERR(state->handle, "Out of memory!"); > + return -1; > + } > + > + if (list) > + list->next = new_sattr; > + else { > + if (state->base->segregate_attributes) { > + segregate_attributes_rule_t *s; > + for (s = state->base->segregate_attributes; s->next; s = s->next) {} > + s->next = new_sattr; > + } else > + state->base->segregate_attributes = new_sattr; > + } > + list = new_sattr; > + } > + > + return 0; > +} > + > /* Copy a module over to a base, remapping all values within. After > * all identifiers and rules are done, copy the scoping information. > * This is when it checks for duplicate declarations. */ > @@ -1891,6 +1930,11 @@ static int copy_module(link_state_t * state, policy_module_t * module) > } > } > > + ret = copy_segregate_attributes(state, module); > + if (ret) { > + return ret; > + } > + > return 0; > } > > diff --git a/libsepol/src/policydb.c b/libsepol/src/policydb.c > index fc260eb6..9dbb9f44 100644 > --- a/libsepol/src/policydb.c > +++ b/libsepol/src/policydb.c > @@ -334,6 +334,13 @@ static const struct policydb_compat_info policydb_compat[] = { > .ocon_num = OCON_IBENDPORT + 1, > .target_platform = SEPOL_TARGET_SELINUX, > }, > + { > + .type = POLICY_BASE, > + .version = MOD_POLICYDB_VERSION_SEGREGATE_ATTRIBUTES, > + .sym_num = SYM_NUM, > + .ocon_num = OCON_IBENDPORT + 1, > + .target_platform = SEPOL_TARGET_SELINUX, > + }, > { > .type = POLICY_MOD, > .version = MOD_POLICYDB_VERSION_BASE, > @@ -460,6 +467,13 @@ static const struct policydb_compat_info policydb_compat[] = { > .ocon_num = 0, > .target_platform = SEPOL_TARGET_SELINUX, > }, > + { > + .type = POLICY_MOD, > + .version = MOD_POLICYDB_VERSION_SEGREGATE_ATTRIBUTES, > + .sym_num = SYM_NUM, > + .ocon_num = 0, > + .target_platform = SEPOL_TARGET_SELINUX, > + }, > }; > > #if 0 > @@ -760,6 +774,20 @@ void avrule_list_destroy(avrule_t * x) > } > } > > +void segregate_attributes_rule_init(segregate_attributes_rule_t * x) > +{ > + ebitmap_init(&x->attrs); > + x->next = NULL; > +} > + > + > +void segregate_attributes_rule_destroy(segregate_attributes_rule_t * x) > +{ > + if (!x) > + return; > + ebitmap_destroy(&x->attrs); > +} > + > /* > * Initialize the role table by implicitly adding role 'object_r'. If > * the policy is a module, set object_r's scope to be SCOPE_REQ, > @@ -1492,6 +1520,7 @@ void policydb_destroy(policydb_t * p) > unsigned int i; > role_allow_t *ra, *lra = NULL; > role_trans_t *tr, *ltr = NULL; > + segregate_attributes_rule_t *sattr, *sattr_next; > > if (!p) > return; > @@ -1585,6 +1614,12 @@ void policydb_destroy(policydb_t * p) > free(p->attr_type_map); > } > > + for (sattr = p->segregate_attributes; sattr; sattr = sattr_next) { > + sattr_next = sattr->next; > + segregate_attributes_rule_destroy(sattr); > + free(sattr); > + } > + > return; > } > > @@ -4174,6 +4209,41 @@ static int scope_read(policydb_t * p, int symnum, struct policy_file *fp) > return -1; > } > > +static int segregate_attributes_read(policydb_t * p, struct policy_file *fp) > +{ > + segregate_attributes_rule_t *list = NULL; > + uint32_t buf, nel, i; > + int rc; > + > + rc = next_entry(&buf, fp, sizeof(uint32_t)); > + if (rc < 0) > + return -1; > + nel = le32_to_cpu(buf); > + for (i = 0; i < nel; i++) { > + segregate_attributes_rule_t *sattr; > + > + sattr = malloc(sizeof(segregate_attributes_rule_t)); > + if (!sattr) > + return -1; > + > + segregate_attributes_rule_init(sattr); > + > + if (ebitmap_read(&sattr->attrs, fp) < 0) { > + ebitmap_destroy(&sattr->attrs); > + free(sattr); > + return -1; > + } > + > + if (list) > + list->next = sattr; > + else > + p->segregate_attributes = sattr; > + list = sattr; > + } > + > + return 0; > +} > + > static sepol_security_class_t policydb_string_to_security_class( > struct policydb *policydb, > const char *class_name) > @@ -4570,6 +4640,12 @@ int policydb_read(policydb_t * p, struct policy_file *fp, unsigned verbose) > } > } > > + if (p->policyvers >= MOD_POLICYDB_VERSION_SEGREGATE_ATTRIBUTES && > + p->policy_type != POLICY_KERN) { > + if (segregate_attributes_read(p, fp)) > + return POLICYDB_ERROR; > + } > + > if (validate_policydb(fp->handle, p)) > goto bad; > > diff --git a/libsepol/src/policydb_validate.c b/libsepol/src/policydb_validate.c > index 99d4eb7f..6331c3ce 100644 > --- a/libsepol/src/policydb_validate.c > +++ b/libsepol/src/policydb_validate.c > @@ -1270,6 +1270,32 @@ bad: > return -1; > } > > +static int validate_segregate_attributes(sepol_handle_t *handle, policydb_t *p, validate_t flavors[]) > +{ > + segregate_attributes_rule_t *sattr; > + ebitmap_node_t *node; > + unsigned int i; > + > + for (sattr = p->segregate_attributes; sattr; sattr = sattr->next) { > + if (ebitmap_cardinality(&sattr->attrs) < 2) > + goto bad; > + > + if (validate_ebitmap(&sattr->attrs, &flavors[SYM_TYPES])) > + goto bad; > + > + ebitmap_for_each_positive_bit(&sattr->attrs, node, i) { > + if (p->type_val_to_struct[i]->flavor != TYPE_ATTRIB) > + goto bad; > + } > + } > + > + return 0; > + > +bad: > + ERR(handle, "Invalid segregate attributes definition"); > + return -1; > +} > + > static int validate_properties(sepol_handle_t *handle, policydb_t *p) > { > switch (p->policy_type) { > @@ -1376,6 +1402,9 @@ int validate_policydb(sepol_handle_t *handle, policydb_t *p) > if (validate_permissives(handle, p, flavors)) > goto bad; > > + if (validate_segregate_attributes(handle, p, flavors)) > + goto bad; > + > validate_array_destroy(flavors); > > return 0; > diff --git a/libsepol/src/write.c b/libsepol/src/write.c > index a9fdf93a..81323df9 100644 > --- a/libsepol/src/write.c > +++ b/libsepol/src/write.c > @@ -58,9 +58,9 @@ struct policy_data { > static int avrule_write_list(policydb_t *p, > avrule_t * avrules, struct policy_file *fp); > > -static int ebitmap_write(ebitmap_t * e, struct policy_file *fp) > +static int ebitmap_write(const ebitmap_t * e, struct policy_file *fp) > { > - ebitmap_node_t *n; > + const ebitmap_node_t *n; > uint32_t buf[32], bit, count; > uint64_t map; > size_t items; > @@ -2191,6 +2191,30 @@ static int role_attr_uncount(hashtab_key_t key __attribute__ ((unused)), > return 0; > } > > +static int segregate_attributes_write(const policydb_t *p, struct policy_file *fp) > +{ > + const segregate_attributes_rule_t *sattr; > + size_t items; > + uint32_t buf, count = 0; > + > + for (sattr = p->segregate_attributes; sattr; sattr = sattr->next) { > + if (__builtin_add_overflow(count, 1, &count)) > + return POLICYDB_ERROR; > + } > + > + buf = cpu_to_le32(count); > + items = put_entry(&buf, sizeof(uint32_t), 1, fp); > + if (items != 1) > + return POLICYDB_ERROR; > + > + for (sattr = p->segregate_attributes; sattr; sattr = sattr->next) { > + if (ebitmap_write(&sattr->attrs, fp)) > + return POLICYDB_ERROR; > + } > + > + return POLICYDB_SUCCESS; > +} > + > /* > * Write the configuration data in a policy database > * structure to a policy database binary representation > @@ -2413,5 +2437,11 @@ int policydb_write(policydb_t * p, struct policy_file *fp) > } > } > > + if (p->policyvers >= MOD_POLICYDB_VERSION_SEGREGATE_ATTRIBUTES && > + p->policy_type != POLICY_KERN) { > + if (segregate_attributes_write(p, fp)) > + return POLICYDB_ERROR; > + } > + > return POLICYDB_SUCCESS; > } > -- > 2.36.1 >
