diff options
Diffstat (limited to 'security/selinux/ss/services.c')
| -rw-r--r-- | security/selinux/ss/services.c | 172 |
1 files changed, 171 insertions, 1 deletions
diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c index 5a0536bddc63..4f233d9960e7 100644 --- a/security/selinux/ss/services.c +++ b/security/selinux/ss/services.c @@ -88,6 +88,11 @@ static u32 latest_granting; static int context_struct_to_string(struct context *context, char **scontext, u32 *scontext_len); +static int context_struct_compute_av(struct context *scontext, + struct context *tcontext, + u16 tclass, + u32 requested, + struct av_decision *avd); /* * Return the boolean value of a constraint expression * when it is applied to the specified source and target @@ -274,6 +279,100 @@ mls_ops: } /* + * security_boundary_permission - drops violated permissions + * on boundary constraint. + */ +static void type_attribute_bounds_av(struct context *scontext, + struct context *tcontext, + u16 tclass, + u32 requested, + struct av_decision *avd) +{ + struct context lo_scontext; + struct context lo_tcontext; + struct av_decision lo_avd; + struct type_datum *source + = policydb.type_val_to_struct[scontext->type - 1]; + struct type_datum *target + = policydb.type_val_to_struct[tcontext->type - 1]; + u32 masked = 0; + + if (source->bounds) { + memset(&lo_avd, 0, sizeof(lo_avd)); + + memcpy(&lo_scontext, scontext, sizeof(lo_scontext)); + lo_scontext.type = source->bounds; + + context_struct_compute_av(&lo_scontext, + tcontext, + tclass, + requested, + &lo_avd); + if ((lo_avd.allowed & avd->allowed) == avd->allowed) + return; /* no masked permission */ + masked = ~lo_avd.allowed & avd->allowed; + } + + if (target->bounds) { + memset(&lo_avd, 0, sizeof(lo_avd)); + + memcpy(&lo_tcontext, tcontext, sizeof(lo_tcontext)); + lo_tcontext.type = target->bounds; + + context_struct_compute_av(scontext, + &lo_tcontext, + tclass, + requested, + &lo_avd); + if ((lo_avd.allowed & avd->allowed) == avd->allowed) + return; /* no masked permission */ + masked = ~lo_avd.allowed & avd->allowed; + } + + if (source->bounds && target->bounds) { + memset(&lo_avd, 0, sizeof(lo_avd)); + /* + * lo_scontext and lo_tcontext are already + * set up. + */ + + context_struct_compute_av(&lo_scontext, + &lo_tcontext, + tclass, + requested, + &lo_avd); + if ((lo_avd.allowed & avd->allowed) == avd->allowed) + return; /* no masked permission */ + masked = ~lo_avd.allowed & avd->allowed; + } + + if (masked) { + struct audit_buffer *ab; + char *stype_name + = policydb.p_type_val_to_name[source->value - 1]; + char *ttype_name + = policydb.p_type_val_to_name[target->value - 1]; + char *tclass_name + = policydb.p_class_val_to_name[tclass - 1]; + + /* mask violated permissions */ + avd->allowed &= ~masked; + + /* notice to userspace via audit message */ + ab = audit_log_start(current->audit_context, + GFP_ATOMIC, AUDIT_SELINUX_ERR); + if (!ab) + return; + + audit_log_format(ab, "av boundary violation: " + "source=%s target=%s tclass=%s", + stype_name, ttype_name, tclass_name); + avc_dump_av(ab, tclass, masked); + audit_log_end(ab); + } +} + +/* * Compute access vectors based on a context structure pair for * the permissions in a particular class. */ @@ -404,6 +503,14 @@ static int context_struct_compute_av(struct context *scontext, PROCESS__DYNTRANSITION); } + /* + * If the given source and target types have boundary + * constraint, lazy checks have to mask any violated + * permission and notice it to userspace via audit. + */ + type_attribute_bounds_av(scontext, tcontext, + tclass, requested, avd); + return 0; inval_class: @@ -549,6 +656,69 @@ out: return rc; } +/* + * security_bounded_transition - check whether the given + * transition is directed to bounded, or not. + * It returns 0, if @newsid is bounded by @oldsid. + * Otherwise, it returns error code. + * + * @oldsid : current security identifier + * @newsid : destinated security identifier + */ +int security_bounded_transition(u32 old_sid, u32 new_sid) +{ + struct context *old_context, *new_context; + struct type_datum *type; + int index; + int rc = -EINVAL; + + read_lock(&policy_rwlock); + + old_context = sidtab_search(&sidtab, old_sid); + if (!old_context) { + printk(KERN_ERR "SELinux: %s: unrecognized SID %u\n", + __func__, old_sid); + goto out; + } + + new_context = sidtab_search(&sidtab, new_sid); + if (!new_context) { + printk(KERN_ERR "SELinux: %s: unrecognized SID %u\n", + __func__, new_sid); + goto out; + } + + /* type/domain unchaned */ + if (old_context->type == new_context->type) { + rc = 0; + goto out; + } + + index = new_context->type; + while (true) { + type = policydb.type_val_to_struct[index - 1]; + BUG_ON(!type); + + /* not bounded anymore */ + if (!type->bounds) { + rc = -EPERM; + break; + } + + /* @newsid is bounded by @oldsid */ + if (type->bounds == old_context->type) { + rc = 0; + break; + } + index = type->bounds; + } +out: + read_unlock(&policy_rwlock); + + return rc; +} + + /** * security_compute_av - Compute access vector decisions. * @ssid: source security identifier @@ -794,7 +964,7 @@ static int string_to_context_struct(struct policydb *pol, *p++ = 0; typdatum = hashtab_search(pol->p_types.table, scontextp); - if (!typdatum) + if (!typdatum || typdatum->attribute) goto out; ctx->type = typdatum->value; |