// SPDX-License-Identifier: GPL-2.0-only
/*
 * Implementation of the security services.
 *
 * Authors : Stephen Smalley, <sds@tycho.nsa.gov>
 *           James Morris <jmorris@redhat.com>
 *
 * Updated: Trusted Computer Solutions, Inc. <dgoeddel@trustedcs.com>
 *
 *      Support for enhanced MLS infrastructure.
 *      Support for context based audit filters.
 *
 * Updated: Frank Mayer <mayerf@tresys.com> and Karl MacMillan <kmacmillan@tresys.com>
 *
 *      Added conditional policy language extensions
 *
 * Updated: Hewlett-Packard <paul@paul-moore.com>
 *
 *      Added support for NetLabel
 *      Added support for the policy capability bitmap
 *
 * Updated: Chad Sellers <csellers@tresys.com>
 *
 *  Added validation of kernel classes and permissions
 *
 * Updated: KaiGai Kohei <kaigai@ak.jp.nec.com>
 *
 *  Added support for bounds domain and audit messaged on masked permissions
 *
 * Updated: Guido Trentalancia <guido@trentalancia.com>
 *
 *  Added support for runtime switching of the policy type
 *
 * Copyright (C) 2008, 2009 NEC Corporation
 * Copyright (C) 2006, 2007 Hewlett-Packard Development Company, L.P.
 * Copyright (C) 2004-2006 Trusted Computer Solutions, Inc.
 * Copyright (C) 2003 - 2004, 2006 Tresys Technology, LLC
 * Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
 */
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/spinlock.h>
#include <linux/rcupdate.h>
#include <linux/errno.h>
#include <linux/in.h>
#include <linux/sched.h>
#include <linux/audit.h>
#include <linux/vmalloc.h>
#include <linux/lsm_hooks.h>
#include <net/netlabel.h>

#include "flask.h"
#include "avc.h"
#include "avc_ss.h"
#include "security.h"
#include "context.h"
#include "policydb.h"
#include "sidtab.h"
#include "services.h"
#include "conditional.h"
#include "mls.h"
#include "objsec.h"
#include "netlabel.h"
#include "xfrm.h"
#include "ebitmap.h"
#include "audit.h"
#include "policycap_names.h"
#include "ima.h"

struct convert_context_args {
        struct selinux_state *state;
        struct policydb *oldp;
        struct policydb *newp;
};

struct selinux_policy_convert_data {
        struct convert_context_args args;
        struct sidtab_convert_params sidtab_params;
};

/* Forward declaration. */
static int context_struct_to_string(struct policydb *policydb,
                                    struct context *context,
                                    char **scontext,
                                    u32 *scontext_len);

static int sidtab_entry_to_string(struct policydb *policydb,
                                  struct sidtab *sidtab,
                                  struct sidtab_entry *entry,
                                  char **scontext,
                                  u32 *scontext_len);

static void context_struct_compute_av(struct policydb *policydb,
                                      struct context *scontext,
                                      struct context *tcontext,
                                      u16 tclass,
                                      struct av_decision *avd,
                                      struct extended_perms *xperms);

static int selinux_set_mapping(struct policydb *pol,
                               struct security_class_mapping *map,
                               struct selinux_map *out_map)
{
        u16 i, j;
        unsigned k;
        bool print_unknown_handle = false;

        /* Find number of classes in the input mapping */
        if (!map)
                return -EINVAL;
        i = 0;
        while (map[i].name)
                i++;

        /* Allocate space for the class records, plus one for class zero */
        out_map->mapping = kcalloc(++i, sizeof(*out_map->mapping), GFP_ATOMIC);
        if (!out_map->mapping)
                return -ENOMEM;

        /* Store the raw class and permission values */
        j = 0;
        while (map[j].name) {
                struct security_class_mapping *p_in = map + (j++);
                struct selinux_mapping *p_out = out_map->mapping + j;

                /* An empty class string skips ahead */
                if (!strcmp(p_in->name, "")) {
                        p_out->num_perms = 0;
                        continue;
                }

                p_out->value = string_to_security_class(pol, p_in->name);
                if (!p_out->value) {
                        pr_info("SELinux:  Class %s not defined in policy.\n",
                               p_in->name);
                        if (pol->reject_unknown)
                                goto err;
                        p_out->num_perms = 0;
                        print_unknown_handle = true;
                        continue;
                }

                k = 0;
                while (p_in->perms[k]) {
                        /* An empty permission string skips ahead */
                        if (!*p_in->perms[k]) {
                                k++;
                                continue;
                        }
                        p_out->perms[k] = string_to_av_perm(pol, p_out->value,
                                                            p_in->perms[k]);
                        if (!p_out->perms[k]) {
                                pr_info("SELinux:  Permission %s in class %s not defined in policy.\n",
                                       p_in->perms[k], p_in->name);
                                if (pol->reject_unknown)
                                        goto err;
                                print_unknown_handle = true;
                        }

                        k++;
                }
                p_out->num_perms = k;
        }

        if (print_unknown_handle)
                pr_info("SELinux: the above unknown classes and permissions will be %s\n",
                       pol->allow_unknown ? "allowed" : "denied");

        out_map->size = i;
        return 0;
err:
        kfree(out_map->mapping);
        out_map->mapping = NULL;
        return -EINVAL;
}

/*
 * Get real, policy values from mapped values
 */

static u16 unmap_class(struct selinux_map *map, u16 tclass)
{
        if (tclass < map->size)
                return map->mapping[tclass].value;

        return tclass;
}

/*
 * Get kernel value for class from its policy value
 */
static u16 map_class(struct selinux_map *map, u16 pol_value)
{
        u16 i;

        for (i = 1; i < map->size; i++) {
                if (map->mapping[i].value == pol_value)
                        return i;
        }

        return SECCLASS_NULL;
}

static void map_decision(struct selinux_map *map,
                         u16 tclass, struct av_decision *avd,
                         int allow_unknown)
{
        if (tclass < map->size) {
                struct selinux_mapping *mapping = &map->mapping[tclass];
                unsigned int i, n = mapping->num_perms;
                u32 result;

                for (i = 0, result = 0; i < n; i++) {
                        if (avd->allowed & mapping->perms[i])
                                result |= 1<<i;
                        if (allow_unknown && !mapping->perms[i])
                                result |= 1<<i;
                }
                avd->allowed = result;

                for (i = 0, result = 0; i < n; i++)
                        if (avd->auditallow & mapping->perms[i])
                                result |= 1<<i;
                avd->auditallow = result;

                for (i = 0, result = 0; i < n; i++) {
                        if (avd->auditdeny & mapping->perms[i])
                                result |= 1<<i;
                        if (!allow_unknown && !mapping->perms[i])
                                result |= 1<<i;
                }
                /*
                 * In case the kernel has a bug and requests a permission
                 * between num_perms and the maximum permission number, we
                 * should audit that denial
                 */
                for (; i < (sizeof(u32)*8); i++)
                        result |= 1<<i;
                avd->auditdeny = result;
        }
}

int security_mls_enabled(struct selinux_state *state)
{
        int mls_enabled;
        struct selinux_policy *policy;

        if (!selinux_initialized(state))
                return 0;

        rcu_read_lock();
        policy = rcu_dereference(state->policy);
        mls_enabled = policy->policydb.mls_enabled;
        rcu_read_unlock();
        return mls_enabled;
}

/*
 * Return the boolean value of a constraint expression
 * when it is applied to the specified source and target
 * security contexts.
 *
 * xcontext is a special beast...  It is used by the validatetrans rules
 * only.  For these rules, scontext is the context before the transition,
 * tcontext is the context after the transition, and xcontext is the context
 * of the process performing the transition.  All other callers of
 * constraint_expr_eval should pass in NULL for xcontext.
 */
static int constraint_expr_eval(struct policydb *policydb,
                                struct context *scontext,
                                struct context *tcontext,
                                struct context *xcontext,
                                struct constraint_expr *cexpr)
{
        u32 val1, val2;
        struct context *c;
        struct role_datum *r1, *r2;
        struct mls_level *l1, *l2;
        struct constraint_expr *e;
        int s[CEXPR_MAXDEPTH];
        int sp = -1;

        for (e = cexpr; e; e = e->next) {
                switch (e->expr_type) {
                case CEXPR_NOT:
                        BUG_ON(sp < 0);
                        s[sp] = !s[sp];
                        break;
                case CEXPR_AND:
                        BUG_ON(sp < 1);
                        sp--;
                        s[sp] &= s[sp + 1];
                        break;
                case CEXPR_OR:
                        BUG_ON(sp < 1);
                        sp--;
                        s[sp] |= s[sp + 1];
                        break;
                case CEXPR_ATTR:
                        if (sp == (CEXPR_MAXDEPTH - 1))
                                return 0;
                        switch (e->attr) {
                        case CEXPR_USER:
                                val1 = scontext->user;
                                val2 = tcontext->user;
                                break;
                        case CEXPR_TYPE:
                                val1 = scontext->type;
                                val2 = tcontext->type;
                                break;
                        case CEXPR_ROLE:
                                val1 = scontext->role;
                                val2 = tcontext->role;
                                r1 = policydb->role_val_to_struct[val1 - 1];
                                r2 = policydb->role_val_to_struct[val2 - 1];
                                switch (e->op) {
                                case CEXPR_DOM:
                                        s[++sp] = ebitmap_get_bit(&r1->dominates,
                                                                  val2 - 1);
                                        continue;
                                case CEXPR_DOMBY:
                                        s[++sp] = ebitmap_get_bit(&r2->dominates,
                                                                  val1 - 1);
                                        continue;
                                case CEXPR_INCOMP:
                                        s[++sp] = (!ebitmap_get_bit(&r1->dominates,
                                                                    val2 - 1) &&
                                                   !ebitmap_get_bit(&r2->dominates,
                                                                    val1 - 1));
                                        continue;
                                default:
                                        break;
                                }
                                break;
                        case CEXPR_L1L2:
                                l1 = &(scontext->range.level[0]);
                                l2 = &(tcontext->range.level[0]);
                                goto mls_ops;
                        case CEXPR_L1H2:
                                l1 = &(scontext->range.level[0]);
                                l2 = &(tcontext->range.level[1]);
                                goto mls_ops;
                        case CEXPR_H1L2:
                                l1 = &(scontext->range.level[1]);
                                l2 = &(tcontext->range.level[0]);
                                goto mls_ops;
                        case CEXPR_H1H2:
                                l1 = &(scontext->range.level[1]);
                                l2 = &(tcontext->range.level[1]);
                                goto mls_ops;
                        case CEXPR_L1H1:
                                l1 = &(scontext->range.level[0]);
                                l2 = &(scontext->range.level[1]);
                                goto mls_ops;
                        case CEXPR_L2H2:
                                l1 = &(tcontext->range.level[0]);
                                l2 = &(tcontext->range.level[1]);
                                goto mls_ops;
mls_ops:
                        switch (e->op) {
                        case CEXPR_EQ:
                                s[++sp] = mls_level_eq(l1, l2);
                                continue;
                        case CEXPR_NEQ:
                                s[++sp] = !mls_level_eq(l1, l2);
                                continue;
                        case CEXPR_DOM:
                                s[++sp] = mls_level_dom(l1, l2);
                                continue;
                        case CEXPR_DOMBY:
                                s[++sp] = mls_level_dom(l2, l1);
                                continue;
                        case CEXPR_INCOMP:
                                s[++sp] = mls_level_incomp(l2, l1);
                                continue;
                        default:
                                BUG();
                                return 0;
                        }
                        break;
                        default:
                                BUG();
                                return 0;
                        }

                        switch (e->op) {
                        case CEXPR_EQ:
                                s[++sp] = (val1 == val2);
                                break;
                        case CEXPR_NEQ:
                                s[++sp] = (val1 != val2);
                                break;
                        default:
                                BUG();
                                return 0;
                        }
                        break;
                case CEXPR_NAMES:
                        if (sp == (CEXPR_MAXDEPTH-1))
                                return 0;
                        c = scontext;
                        if (e->attr & CEXPR_TARGET)
                                c = tcontext;
                        else if (e->attr & CEXPR_XTARGET) {
                                c = xcontext;
                                if (!c) {
                                        BUG();
                                        return 0;
                                }
                        }
                        if (e->attr & CEXPR_USER)
                                val1 = c->user;
                        else if (e->attr & CEXPR_ROLE)
                                val1 = c->role;
                        else if (e->attr & CEXPR_TYPE)
                                val1 = c->type;
                        else {
                                BUG();
                                return 0;
                        }

                        switch (e->op) {
                        case CEXPR_EQ:
                                s[++sp] = ebitmap_get_bit(&e->names, val1 - 1);
                                break;
                        case CEXPR_NEQ:
                                s[++sp] = !ebitmap_get_bit(&e->names, val1 - 1);
                                break;
                        default:
                                BUG();
                                return 0;
                        }
                        break;
                default:
                        BUG();
                        return 0;
                }
        }

        BUG_ON(sp != 0);
        return s[0];
}

/*
 * security_dump_masked_av - dumps masked permissions during
 * security_compute_av due to RBAC, MLS/Constraint and Type bounds.
 */
static int dump_masked_av_helper(void *k, void *d, void *args)
{
        struct perm_datum *pdatum = d;
        char **permission_names = args;

        BUG_ON(pdatum->value < 1 || pdatum->value > 32);

        permission_names[pdatum->value - 1] = (char *)k;

        return 0;
}

static void security_dump_masked_av(struct policydb *policydb,
                                    struct context *scontext,
                                    struct context *tcontext,
                                    u16 tclass,
                                    u32 permissions,
                                    const char *reason)
{
        struct common_datum *common_dat;
        struct class_datum *tclass_dat;
        struct audit_buffer *ab;
        char *tclass_name;
        char *scontext_name = NULL;
        char *tcontext_name = NULL;
        char *permission_names[32];
        int index;
        u32 length;
        bool need_comma = false;

        if (!permissions)
                return;

        tclass_name = sym_name(policydb, SYM_CLASSES, tclass - 1);
        tclass_dat = policydb->class_val_to_struct[tclass - 1];
        common_dat = tclass_dat->comdatum;

        /* init permission_names */
        if (common_dat &&
            hashtab_map(&common_dat->permissions.table,
                        dump_masked_av_helper, permission_names) < 0)
                goto out;

        if (hashtab_map(&tclass_dat->permissions.table,
                        dump_masked_av_helper, permission_names) < 0)
                goto out;

        /* get scontext/tcontext in text form */
        if (context_struct_to_string(policydb, scontext,
                                     &scontext_name, &length) < 0)
                goto out;

        if (context_struct_to_string(policydb, tcontext,
                                     &tcontext_name, &length) < 0)
                goto out;

        /* audit a message */
        ab = audit_log_start(audit_context(),
                             GFP_ATOMIC, AUDIT_SELINUX_ERR);
        if (!ab)
                goto out;

        audit_log_format(ab, "op=security_compute_av reason=%s "
                         "scontext=%s tcontext=%s tclass=%s perms=",
                         reason, scontext_name, tcontext_name, tclass_name);

        for (index = 0; index < 32; index++) {
                u32 mask = (1 << index);

                if ((mask & permissions) == 0)
                        continue;

                audit_log_format(ab, "%s%s",
                                 need_comma ? "," : "",
                                 permission_names[index]
                                 ? permission_names[index] : "????");
                need_comma = true;
        }
        audit_log_end(ab);
out:
        /* release scontext/tcontext */
        kfree(tcontext_name);
        kfree(scontext_name);

        return;
}

/*
 * security_boundary_permission - drops violated permissions
 * on boundary constraint.
 */
static void type_attribute_bounds_av(struct policydb *policydb,
                                     struct context *scontext,
                                     struct context *tcontext,
                                     u16 tclass,
                                     struct av_decision *avd)
{
        struct context lo_scontext;
        struct context lo_tcontext, *tcontextp = tcontext;
        struct av_decision lo_avd;
        struct type_datum *source;
        struct type_datum *target;
        u32 masked = 0;

        source = policydb->type_val_to_struct[scontext->type - 1];
        BUG_ON(!source);

        if (!source->bounds)
                return;

        target = policydb->type_val_to_struct[tcontext->type - 1];
        BUG_ON(!target);

        memset(&lo_avd, 0, sizeof(lo_avd));

        memcpy(&lo_scontext, scontext, sizeof(lo_scontext));
        lo_scontext.type = source->bounds;

        if (target->bounds) {
                memcpy(&lo_tcontext, tcontext, sizeof(lo_tcontext));
                lo_tcontext.type = target->bounds;
                tcontextp = &lo_tcontext;
        }

        context_struct_compute_av(policydb, &lo_scontext,
                                  tcontextp,
                                  tclass,
                                  &lo_avd,
                                  NULL);

        masked = ~lo_avd.allowed & avd->allowed;

        if (likely(!masked))
                return;         /* no masked permission */

        /* mask violated permissions */
        avd->allowed &= ~masked;

        /* audit masked permissions */
        security_dump_masked_av(policydb, scontext, tcontext,
                                tclass, masked, "bounds");
}

/*
 * flag which drivers have permissions
 * only looking for ioctl based extended permssions
 */
void services_compute_xperms_drivers(
                struct extended_perms *xperms,
                struct avtab_node *node)
{
        unsigned int i;

        if (node->datum.u.xperms->specified == AVTAB_XPERMS_IOCTLDRIVER) {
                /* if one or more driver has all permissions allowed */
                for (i = 0; i < ARRAY_SIZE(xperms->drivers.p); i++)
                        xperms->drivers.p[i] |= node->datum.u.xperms->perms.p[i];
        } else if (node->datum.u.xperms->specified == AVTAB_XPERMS_IOCTLFUNCTION) {
                /* if allowing permissions within a driver */
                security_xperm_set(xperms->drivers.p,
                                        node->datum.u.xperms->driver);
        }

        xperms->len = 1;
}

/*
 * Compute access vectors and extended permissions based on a context
 * structure pair for the permissions in a particular class.
 */
static void context_struct_compute_av(struct policydb *policydb,
                                      struct context *scontext,
                                      struct context *tcontext,
                                      u16 tclass,
                                      struct av_decision *avd,
                                      struct extended_perms *xperms)
{
        struct constraint_node *constraint;
        struct role_allow *ra;
        struct avtab_key avkey;
        struct avtab_node *node;
        struct class_datum *tclass_datum;
        struct ebitmap *sattr, *tattr;
        struct ebitmap_node *snode, *tnode;
        unsigned int i, j;

        avd->allowed = 0;
        avd->auditallow = 0;
        avd->auditdeny = 0xffffffff;
        if (xperms) {
                memset(&xperms->drivers, 0, sizeof(xperms->drivers));
                xperms->len = 0;
        }

        if (unlikely(!tclass || tclass > policydb->p_classes.nprim)) {
                if (printk_ratelimit())
                        pr_warn("SELinux:  Invalid class %hu\n", tclass);
                return;
        }

        tclass_datum = policydb->class_val_to_struct[tclass - 1];

        /*
         * If a specific type enforcement rule was defined for
         * this permission check, then use it.
         */
        avkey.target_class = tclass;
        avkey.specified = AVTAB_AV | AVTAB_XPERMS;
        sattr = &policydb->type_attr_map_array[scontext->type - 1];
        tattr = &policydb->type_attr_map_array[tcontext->type - 1];
        ebitmap_for_each_positive_bit(sattr, snode, i) {
                ebitmap_for_each_positive_bit(tattr, tnode, j) {
                        avkey.source_type = i + 1;
                        avkey.target_type = j + 1;
                        for (node = avtab_search_node(&policydb->te_avtab,
                                                      &avkey);
                             node;
                             node = avtab_search_node_next(node, avkey.specified)) {
                                if (node->key.specified == AVTAB_ALLOWED)
                                        avd->allowed |= node->datum.u.data;
                                else if (node->key.specified == AVTAB_AUDITALLOW)
                                        avd->auditallow |= node->datum.u.data;
                                else if (node->key.specified == AVTAB_AUDITDENY)
                                        avd->auditdeny &= node->datum.u.data;
                                else if (xperms && (node->key.specified & AVTAB_XPERMS))
                                        services_compute_xperms_drivers(xperms, node);
                        }

                        /* Check conditional av table for additional permissions */
                        cond_compute_av(&policydb->te_cond_avtab, &avkey,
                                        avd, xperms);

                }
        }

        /*
         * Remove any permissions prohibited by a constraint (this includes
         * the MLS policy).
         */
        constraint = tclass_datum->constraints;
        while (constraint) {
                if ((constraint->permissions & (avd->allowed)) &&
                    !constraint_expr_eval(policydb, scontext, tcontext, NULL,
                                          constraint->expr)) {
                        avd->allowed &= ~(constraint->permissions);
                }
                constraint = constraint->next;
        }

        /*
         * If checking process transition permission and the
         * role is changing, then check the (current_role, new_role)
         * pair.
         */
        if (tclass == policydb->process_class &&
            (avd->allowed & policydb->process_trans_perms) &&
            scontext->role != tcontext->role) {
                for (ra = policydb->role_allow; ra; ra = ra->next) {
                        if (scontext->role == ra->role &&
                            tcontext->role == ra->new_role)
                                break;
                }
                if (!ra)
                        avd->allowed &= ~policydb->process_trans_perms;
        }

        /*
         * 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(policydb, scontext, tcontext,
                                 tclass, avd);
}

static int security_validtrans_handle_fail(struct selinux_state *state,
                                        struct selinux_policy *policy,
                                        struct sidtab_entry *oentry,
                                        struct sidtab_entry *nentry,
                                        struct sidtab_entry *tentry,
                                        u16 tclass)
{
        struct policydb *p = &policy->policydb;
        struct sidtab *sidtab = policy->sidtab;
        char *o = NULL, *n = NULL, *t = NULL;
        u32 olen, nlen, tlen;

        if (sidtab_entry_to_string(p, sidtab, oentry, &o, &olen))
                goto out;
        if (sidtab_entry_to_string(p, sidtab, nentry, &n, &nlen))
                goto out;
        if (sidtab_entry_to_string(p, sidtab, tentry, &t, &tlen))
                goto out;
        audit_log(audit_context(), GFP_ATOMIC, AUDIT_SELINUX_ERR,
                  "op=security_validate_transition seresult=denied"
                  " oldcontext=%s newcontext=%s taskcontext=%s tclass=%s",
                  o, n, t, sym_name(p, SYM_CLASSES, tclass-1));
out:
        kfree(o);
        kfree(n);
        kfree(t);

        if (!enforcing_enabled(state))
                return 0;
        return -EPERM;
}

static int security_compute_validatetrans(struct selinux_state *state,
                                          u32 oldsid, u32 newsid, u32 tasksid,
                                          u16 orig_tclass, bool user)
{
        struct selinux_policy *policy;
        struct policydb *policydb;
        struct sidtab *sidtab;
        struct sidtab_entry *oentry;
        struct sidtab_entry *nentry;
        struct sidtab_entry *tentry;
        struct class_datum *tclass_datum;
        struct constraint_node *constraint;
        u16 tclass;
        int rc = 0;


        if (!selinux_initialized(state))
                return 0;

        rcu_read_lock();

        policy = rcu_dereference(state->policy);
        policydb = &policy->policydb;
        sidtab = policy->sidtab;

        if (!user)
                tclass = unmap_class(&policy->map, orig_tclass);
        else
                tclass = orig_tclass;

        if (!tclass || tclass > policydb->p_classes.nprim) {
                rc = -EINVAL;
                goto out;
        }
        tclass_datum = policydb->class_val_to_struct[tclass - 1];

        oentry = sidtab_search_entry(sidtab, oldsid);
        if (!oentry) {
                pr_err("SELinux: %s:  unrecognized SID %d\n",
                        __func__, oldsid);
                rc = -EINVAL;
                goto out;
        }

        nentry = sidtab_search_entry(sidtab, newsid);
        if (!nentry) {
                pr_err("SELinux: %s:  unrecognized SID %d\n",
                        __func__, newsid);
                rc = -EINVAL;
                goto out;
        }

        tentry = sidtab_search_entry(sidtab, tasksid);
        if (!tentry) {
                pr_err("SELinux: %s:  unrecognized SID %d\n",
                        __func__, tasksid);
                rc = -EINVAL;
                goto out;
        }

        constraint = tclass_datum->validatetrans;
        while (constraint) {
                if (!constraint_expr_eval(policydb, &oentry->context,
                                          &nentry->context, &tentry->context,
                                          constraint->expr)) {
                        if (user)
                                rc = -EPERM;
                        else
                                rc = security_validtrans_handle_fail(state,
                                                                policy,
                                                                oentry,
                                                                nentry,
                                                                tentry,
                                                                tclass);
                        goto out;
                }
                constraint = constraint->next;
        }

out:
        rcu_read_unlock();
        return rc;
}

int security_validate_transition_user(struct selinux_state *state,
                                      u32 oldsid, u32 newsid, u32 tasksid,
                                      u16 tclass)
{
        return security_compute_validatetrans(state, oldsid, newsid, tasksid,
                                              tclass, true);
}

int security_validate_transition(struct selinux_state *state,
                                 u32 oldsid, u32 newsid, u32 tasksid,
                                 u16 orig_tclass)
{
        return security_compute_validatetrans(state, oldsid, newsid, tasksid,
                                              orig_tclass, false);
}

/*
 * 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.
 *
 * @state: SELinux state
 * @oldsid : current security identifier
 * @newsid : destinated security identifier
 */
int security_bounded_transition(struct selinux_state *state,
                                u32 old_sid, u32 new_sid)
{
        struct selinux_policy *policy;
        struct policydb *policydb;
        struct sidtab *sidtab;
        struct sidtab_entry *old_entry, *new_entry;
        struct type_datum *type;
        int index;
        int rc;

        if (!selinux_initialized(state))
                return 0;

        rcu_read_lock();
        policy = rcu_dereference(state->policy);
        policydb = &policy->policydb;
        sidtab = policy->sidtab;

        rc = -EINVAL;
        old_entry = sidtab_search_entry(sidtab, old_sid);
        if (!old_entry) {
                pr_err("SELinux: %s: unrecognized SID %u\n",
                       __func__, old_sid);
                goto out;
        }

        rc = -EINVAL;
        new_entry = sidtab_search_entry(sidtab, new_sid);
        if (!new_entry) {
                pr_err("SELinux: %s: unrecognized SID %u\n",
                       __func__, new_sid);
                goto out;
        }

        rc = 0;
        /* type/domain unchanged */
        if (old_entry->context.type == new_entry->context.type)
                goto out;

        index = new_entry->context.type;
        while (true) {
                type = policydb->type_val_to_struct[index - 1];
                BUG_ON(!type);

                /* not bounded anymore */
                rc = -EPERM;
                if (!type->bounds)
                        break;

                /* @newsid is bounded by @oldsid */
                rc = 0;
                if (type->bounds == old_entry->context.type)
                        break;

                index = type->bounds;
        }

        if (rc) {
                char *old_name = NULL;
                char *new_name = NULL;
                u32 length;

                if (!sidtab_entry_to_string(policydb, sidtab, old_entry,
                                            &old_name, &length) &&
                    !sidtab_entry_to_string(policydb, sidtab, new_entry,
                                            &new_name, &length)) {
                        audit_log(audit_context(),
                                  GFP_ATOMIC, AUDIT_SELINUX_ERR,
                                  "op=security_bounded_transition "
                                  "seresult=denied "
                                  "oldcontext=%s newcontext=%s",
                                  old_name, new_name);
                }
                kfree(new_name);
                kfree(old_name);
        }
out:
        rcu_read_unlock();

        return rc;
}

static void avd_init(struct selinux_policy *policy, struct av_decision *avd)
{
        avd->allowed = 0;
        avd->auditallow = 0;
        avd->auditdeny = 0xffffffff;
        if (policy)
                avd->seqno = policy->latest_granting;
        else
                avd->seqno = 0;
        avd->flags = 0;
}

void services_compute_xperms_decision(struct extended_perms_decision *xpermd,
                                        struct avtab_node *node)
{
        unsigned int i;

        if (node->datum.u.xperms->specified == AVTAB_XPERMS_IOCTLFUNCTION) {
                if (xpermd->driver != node->datum.u.xperms->driver)
                        return;
        } else if (node->datum.u.xperms->specified == AVTAB_XPERMS_IOCTLDRIVER) {
                if (!security_xperm_test(node->datum.u.xperms->perms.p,
                                        xpermd->driver))
                        return;
        } else {
                BUG();
        }

        if (node->key.specified == AVTAB_XPERMS_ALLOWED) {
                xpermd->used |= XPERMS_ALLOWED;
                if (node->datum.u.xperms->specified == AVTAB_XPERMS_IOCTLDRIVER) {
                        memset(xpermd->allowed->p, 0xff,
                                        sizeof(xpermd->allowed->p));
                }
                if (node->datum.u.xperms->specified == AVTAB_XPERMS_IOCTLFUNCTION) {
                        for (i = 0; i < ARRAY_SIZE(xpermd->allowed->p); i++)
                                xpermd->allowed->p[i] |=
                                        node->datum.u.xperms->perms.p[i];
                }
        } else if (node->key.specified == AVTAB_XPERMS_AUDITALLOW) {
                xpermd->used |= XPERMS_AUDITALLOW;
                if (node->datum.u.xperms->specified == AVTAB_XPERMS_IOCTLDRIVER) {
                        memset(xpermd->auditallow->p, 0xff,
                                        sizeof(xpermd->auditallow->p));
                }
                if (node->datum.u.xperms->specified == AVTAB_XPERMS_IOCTLFUNCTION) {
                        for (i = 0; i < ARRAY_SIZE(xpermd->auditallow->p); i++)
                                xpermd->auditallow->p[i] |=
                                        node->datum.u.xperms->perms.p[i];
                }
        } else if (node->key.specified == AVTAB_XPERMS_DONTAUDIT) {
                xpermd->used |= XPERMS_DONTAUDIT;

                if (node->datum.u.xperms->specified == AVTAB_XPERMS_IOCTLDRIVER) {
                        memset(xpermd->dontaudit->p, 0xff,
                                        sizeof(xpermd->dontaudit->p));
                }
                if (node->datum.u.xperms->specified == AVTAB_XPERMS_IOCTLFUNCTION) {
                        for (i = 0; i < ARRAY_SIZE(xpermd->dontaudit->p); i++)
                                xpermd->dontaudit->p[i] |=
                                        node->datum.u.xperms->perms.p[i];
                }
        } else {
                BUG();
        }
}

void security_compute_xperms_decision(struct selinux_state *state,
                                      u32 ssid,
                                      u32 tsid,
                                      u16 orig_tclass,
                                      u8 driver,
                                      struct extended_perms_decision *xpermd)
{
        struct selinux_policy *policy;
        struct policydb *policydb;
        struct sidtab *sidtab;
        u16 tclass;
        struct context *scontext, *tcontext;
        struct avtab_key avkey;
        struct avtab_node *node;
        struct ebitmap *sattr, *tattr;
        struct ebitmap_node *snode, *tnode;
        unsigned int i, j;

        xpermd->driver = driver;
        xpermd->used = 0;
        memset(xpermd->allowed->p, 0, sizeof(xpermd->allowed->p));
        memset(xpermd->auditallow->p, 0, sizeof(xpermd->auditallow->p));
        memset(xpermd->dontaudit->p, 0, sizeof(xpermd->dontaudit->p));

        rcu_read_lock();
        if (!selinux_initialized(state))
                goto allow;

        policy = rcu_dereference(state->policy);
        policydb = &policy->policydb;
        sidtab = policy->sidtab;

        scontext = sidtab_search(sidtab, ssid);
        if (!scontext) {
                pr_err("SELinux: %s:  unrecognized SID %d\n",
                       __func__, ssid);
                goto out;
        }

        tcontext = sidtab_search(sidtab, tsid);
        if (!tcontext) {
                pr_err("SELinux: %s:  unrecognized SID %d\n",
                       __func__, tsid);
                goto out;
        }

        tclass = unmap_class(&policy->map, orig_tclass);
        if (unlikely(orig_tclass && !tclass)) {
                if (policydb->allow_unknown)
                        goto allow;
                goto out;
        }


        if (unlikely(!tclass || tclass > policydb->p_classes.nprim)) {
                pr_warn_ratelimited("SELinux:  Invalid class %hu\n", tclass);
                goto out;
        }

        avkey.target_class = tclass;
        avkey.specified = AVTAB_XPERMS;
        sattr = &policydb->type_attr_map_array[scontext->type - 1];
        tattr = &policydb->type_attr_map_array[tcontext->type - 1];
        ebitmap_for_each_positive_bit(sattr, snode, i) {
                ebitmap_for_each_positive_bit(tattr, tnode, j) {
                        avkey.source_type = i + 1;
                        avkey.target_type = j + 1;
                        for (node = avtab_search_node(&policydb->te_avtab,
                                                      &avkey);
                             node;
                             node = avtab_search_node_next(node, avkey.specified))
                                services_compute_xperms_decision(xpermd, node);

                        cond_compute_xperms(&policydb->te_cond_avtab,
                                                &avkey, xpermd);
                }
        }
out:
        rcu_read_unlock();
        return;
allow:
        memset(xpermd->allowed->p, 0xff, sizeof(xpermd->allowed->p));
        goto out;
}

/**
 * security_compute_av - Compute access vector decisions.
 * @state: SELinux state
 * @ssid: source security identifier
 * @tsid: target security identifier
 * @tclass: target security class
 * @avd: access vector decisions
 * @xperms: extended permissions
 *
 * Compute a set of access vector decisions based on the
 * SID pair (@ssid, @tsid) for the permissions in @tclass.
 */
void security_compute_av(struct selinux_state *state,
                         u32 ssid,
                         u32 tsid,
                         u16 orig_tclass,
                         struct av_decision *avd,
                         struct extended_perms *xperms)
{
        struct selinux_policy *policy;
        struct policydb *policydb;
        struct sidtab *sidtab;
        u16 tclass;
        struct context *scontext = NULL, *tcontext = NULL;

        rcu_read_lock();
        policy = rcu_dereference(state->policy);
        avd_init(policy, avd);
        xperms->len = 0;
        if (!selinux_initialized(state))
                goto allow;

        policydb = &policy->policydb;
        sidtab = policy->sidtab;

        scontext = sidtab_search(sidtab, ssid);
        if (!scontext) {
                pr_err("SELinux: %s:  unrecognized SID %d\n",
                       __func__, ssid);
                goto out;
        }

        /* permissive domain? */
        if (ebitmap_get_bit(&policydb->permissive_map, scontext->type))
                avd->flags |= AVD_FLAGS_PERMISSIVE;

        tcontext = sidtab_search(sidtab, tsid);
        if (!tcontext) {
                pr_err("SELinux: %s:  unrecognized SID %d\n",
                       __func__, tsid);
                goto out;
        }

        tclass = unmap_class(&policy->map, orig_tclass);
        if (unlikely(orig_tclass && !tclass)) {
                if (policydb->allow_unknown)
                        goto allow;
                goto out;
        }
        context_struct_compute_av(policydb, scontext, tcontext, tclass, avd,
                                  xperms);
        map_decision(&policy->map, orig_tclass, avd,
                     policydb->allow_unknown);
out:
        rcu_read_unlock();
        return;
allow:
        avd->allowed = 0xffffffff;
        goto out;
}

void security_compute_av_user(struct selinux_state *state,
                              u32 ssid,
                              u32 tsid,
                              u16 tclass,
                              struct av_decision *avd)
{
        struct selinux_policy *policy;
        struct policydb *policydb;
        struct sidtab *sidtab;
        struct context *scontext = NULL, *tcontext = NULL;

        rcu_read_lock();
        policy = rcu_dereference(state->policy);
        avd_init(policy, avd);
        if (!selinux_initialized(state))
                goto allow;

        policydb = &policy->policydb;
        sidtab = policy->sidtab;

        scontext = sidtab_search(sidtab, ssid);
        if (!scontext) {
                pr_err("SELinux: %s:  unrecognized SID %d\n",
                       __func__, ssid);
                goto out;
        }

        /* permissive domain? */
        if (ebitmap_get_bit(&policydb->permissive_map, scontext->type))
                avd->flags |= AVD_FLAGS_PERMISSIVE;

        tcontext = sidtab_search(sidtab, tsid);
        if (!tcontext) {
                pr_err("SELinux: %s:  unrecognized SID %d\n",
                       __func__, tsid);
                goto out;
        }

        if (unlikely(!tclass)) {
                if (policydb->allow_unknown)
                        goto allow;
                goto out;
        }

        context_struct_compute_av(policydb, scontext, tcontext, tclass, avd,
                                  NULL);
 out:
        rcu_read_unlock();
        return;
allow:
        avd->allowed = 0xffffffff;
        goto out;
}

/*
 * Write the security context string representation of
 * the context structure `context' into a dynamically
 * allocated string of the correct size.  Set `*scontext'
 * to point to this string and set `*scontext_len' to
 * the length of the string.
 */
static int context_struct_to_string(struct policydb *p,
                                    struct context *context,
                                    char **scontext, u32 *scontext_len)
{
        char *scontextp;

        if (scontext)
                *scontext = NULL;
        *scontext_len = 0;

        if (context->len) {
                *scontext_len = context->len;
                if (scontext) {
                        *scontext = kstrdup(context->str, GFP_ATOMIC);
                        if (!(*scontext))
                                return -ENOMEM;
                }
                return 0;
        }

        /* Compute the size of the context. */
        *scontext_len += strlen(sym_name(p, SYM_USERS, context->user - 1)) + 1;
        *scontext_len += strlen(sym_name(p, SYM_ROLES, context->role - 1)) + 1;
        *scontext_len += strlen(sym_name(p, SYM_TYPES, context->type - 1)) + 1;
        *scontext_len += mls_compute_context_len(p, context);

        if (!scontext)
                return 0;

        /* Allocate space for the context; caller must free this space. */
        scontextp = kmalloc(*scontext_len, GFP_ATOMIC);
        if (!scontextp)
                return -ENOMEM;
        *scontext = scontextp;

        /*
         * Copy the user name, role name and type name into the context.
         */
        scontextp += sprintf(scontextp, "%s:%s:%s",
                sym_name(p, SYM_USERS, context->user - 1),
                sym_name(p, SYM_ROLES, context->role - 1),
                sym_name(p, SYM_TYPES, context->type - 1));

        mls_sid_to_context(p, context, &scontextp);

        *scontextp = 0;

        return 0;
}

static int sidtab_entry_to_string(struct policydb *p,
                                  struct sidtab *sidtab,
                                  struct sidtab_entry *entry,
                                  char **scontext, u32 *scontext_len)
{
        int rc = sidtab_sid2str_get(sidtab, entry, scontext, scontext_len);

        if (rc != -ENOENT)
                return rc;

        rc = context_struct_to_string(p, &entry->context, scontext,
                                      scontext_len);
        if (!rc && scontext)
                sidtab_sid2str_put(sidtab, entry, *scontext, *scontext_len);
        return rc;
}

#include "initial_sid_to_string.h"

int security_sidtab_hash_stats(struct selinux_state *state, char *page)
{
        struct selinux_policy *policy;
        int rc;

        if (!selinux_initialized(state)) {
                pr_err("SELinux: %s:  called before initial load_policy\n",
                       __func__);
                return -EINVAL;
        }

        rcu_read_lock();
        policy = rcu_dereference(state->policy);
        rc = sidtab_hash_stats(policy->sidtab, page);
        rcu_read_unlock();

        return rc;
}

const char *security_get_initial_sid_context(u32 sid)
{
        if (unlikely(sid > SECINITSID_NUM))
                return NULL;
        return initial_sid_to_string[sid];
}

static int security_sid_to_context_core(struct selinux_state *state,
                                        u32 sid, char **scontext,
                                        u32 *scontext_len, int force,
                                        int only_invalid)
{
        struct selinux_policy *policy;
        struct policydb *policydb;
        struct sidtab *sidtab;
        struct sidtab_entry *entry;
        int rc = 0;

        if (scontext)
                *scontext = NULL;
        *scontext_len  = 0;

        if (!selinux_initialized(state)) {
                if (sid <= SECINITSID_NUM) {
                        char *scontextp;
                        const char *s = initial_sid_to_string[sid];

                        if (!s)
                                return -EINVAL;
                        *scontext_len = strlen(s) + 1;
                        if (!scontext)
                                return 0;
                        scontextp = kmemdup(s, *scontext_len, GFP_ATOMIC);
                        if (!scontextp)
                                return -ENOMEM;
                        *scontext = scontextp;
                        return 0;
                }
                pr_err("SELinux: %s:  called before initial "
                       "load_policy on unknown SID %d\n", __func__, sid);
                return -EINVAL;
        }
        rcu_read_lock();
        policy = rcu_dereference(state->policy);
        policydb = &policy->policydb;
        sidtab = policy->sidtab;

        if (force)
                entry = sidtab_search_entry_force(sidtab, sid);
        else
                entry = sidtab_search_entry(sidtab, sid);
        if (!entry) {
                pr_err("SELinux: %s:  unrecognized SID %d\n",
                        __func__, sid);
                rc = -EINVAL;
                goto out_unlock;
        }
        if (only_invalid && !entry->context.len)
                goto out_unlock;

        rc = sidtab_entry_to_string(policydb, sidtab, entry, scontext,
                                    scontext_len);

out_unlock:
        rcu_read_unlock();
        return rc;

}

/**
 * security_sid_to_context - Obtain a context for a given SID.
 * @state: SELinux state
 * @sid: security identifier, SID
 * @scontext: security context
 * @scontext_len: length in bytes
 *
 * Write the string representation of the context associated with @sid
 * into a dynamically allocated string of the correct size.  Set @scontext
 * to point to this string and set @scontext_len to the length of the string.
 */
int security_sid_to_context(struct selinux_state *state,
                            u32 sid, char **scontext, u32 *scontext_len)
{
        return security_sid_to_context_core(state, sid, scontext,
                                            scontext_len, 0, 0);
}

int security_sid_to_context_force(struct selinux_state *state, u32 sid,
                                  char **scontext, u32 *scontext_len)
{
        return security_sid_to_context_core(state, sid, scontext,
                                            scontext_len, 1, 0);
}

/**
 * security_sid_to_context_inval - Obtain a context for a given SID if it
 *                                 is invalid.
 * @state: SELinux state
 * @sid: security identifier, SID
 * @scontext: security context
 * @scontext_len: length in bytes
 *
 * Write the string representation of the context associated with @sid
 * into a dynamically allocated string of the correct size, but only if the
 * context is invalid in the current policy.  Set @scontext to point to
 * this string (or NULL if the context is valid) and set @scontext_len to
 * the length of the string (or 0 if the context is valid).
 */
int security_sid_to_context_inval(struct selinux_state *state, u32 sid,
                                  char **scontext, u32 *scontext_len)
{
        return security_sid_to_context_core(state, sid, scontext,
                                            scontext_len, 1, 1);
}

/*
 * Caveat:  Mutates scontext.
 */
static int string_to_context_struct(struct policydb *pol,
                                    struct sidtab *sidtabp,
                                    char *scontext,
                                    struct context *ctx,
                                    u32 def_sid)
{
        struct role_datum *role;
        struct type_datum *typdatum;
        struct user_datum *usrdatum;
        char *scontextp, *p, oldc;
        int rc = 0;

        context_init(ctx);

        /* Parse the security context. */

        rc = -EINVAL;
        scontextp = (char *) scontext;

        /* Extract the user. */
        p = scontextp;
        while (*p && *p != ':')
                p++;

        if (*p == 0)
                goto out;

        *p++ = 0;

        usrdatum = symtab_search(&pol->p_users, scontextp);
        if (!usrdatum)
                goto out;

        ctx->user = usrdatum->value;

        /* Extract role. */
        scontextp = p;
        while (*p && *p != ':')
                p++;

        if (*p == 0)
                goto out;

        *p++ = 0;

        role = symtab_search(&pol->p_roles, scontextp);
        if (!role)
                goto out;
        ctx->role = role->value;

        /* Extract type. */
        scontextp = p;
        while (*p && *p != ':')
                p++;
        oldc = *p;
        *p++ = 0;

        typdatum = symtab_search(&pol->p_types, scontextp);
        if (!typdatum || typdatum->attribute)
                goto out;

        ctx->type = typdatum->value;

        rc = mls_context_to_sid(pol, oldc, p, ctx, sidtabp, def_sid);
        if (rc)
                goto out;

        /* Check the validity of the new context. */
        rc = -EINVAL;
        if (!policydb_context_isvalid(pol, ctx))
                goto out;
        rc = 0;
out:
        if (rc)
                context_destroy(ctx);
        return rc;
}

static int security_context_to_sid_core(struct selinux_state *state,
                                        const char *scontext, u32 scontext_len,
                                        u32 *sid, u32 def_sid, gfp_t gfp_flags,
                                        int force)
{
        struct selinux_policy *policy;
        struct policydb *policydb;
        struct sidtab *sidtab;
        char *scontext2, *str = NULL;
        struct context context;
        int rc = 0;

        /* An empty security context is never valid. */
        if (!scontext_len)
                return -EINVAL;

        /* Copy the string to allow changes and ensure a NUL terminator */
        scontext2 = kmemdup_nul(scontext, scontext_len, gfp_flags);
        if (!scontext2)
                return -ENOMEM;

        if (!selinux_initialized(state)) {
                int i;

                for (i = 1; i < SECINITSID_NUM; i++) {
                        const char *s = initial_sid_to_string[i];

                        if (s && !strcmp(s, scontext2)) {
                                *sid = i;
                                goto out;
                        }
                }
                *sid = SECINITSID_KERNEL;
                goto out;
        }
        *sid = SECSID_NULL;

        if (force) {
                /* Save another copy for storing in uninterpreted form */
                rc = -ENOMEM;
                str = kstrdup(scontext2, gfp_flags);
                if (!str)
                        goto out;
        }
retry:
        rcu_read_lock();
        policy = rcu_dereference(state->policy);
        policydb = &policy->policydb;
        sidtab = policy->sidtab;
        rc = string_to_context_struct(policydb, sidtab, scontext2,
                                      &context, def_sid);
        if (rc == -EINVAL && force) {
                context.str = str;
                context.len = strlen(str) + 1;
                str = NULL;
        } else if (rc)
                goto out_unlock;
        rc = sidtab_context_to_sid(sidtab, &context, sid);
        if (rc == -ESTALE) {
                rcu_read_unlock();
                if (context.str) {
                        str = context.str;
                        context.str = NULL;
                }
                context_destroy(&context);
                goto retry;
        }
        context_destroy(&context);
out_unlock:
        rcu_read_unlock();
out:
        kfree(scontext2);
        kfree(str);
        return rc;
}

/**
 * security_context_to_sid - Obtain a SID for a given security context.
 * @state: SELinux state
 * @scontext: security context
 * @scontext_len: length in bytes
 * @sid: security identifier, SID
 * @gfp: context for the allocation
 *
 * Obtains a SID associated with the security context that
 * has the string representation specified by @scontext.
 * Returns -%EINVAL if the context is invalid, -%ENOMEM if insufficient
 * memory is available, or 0 on success.
 */
int security_context_to_sid(struct selinux_state *state,
                            const char *scontext, u32 scontext_len, u32 *sid,
                            gfp_t gfp)
{
        return security_context_to_sid_core(state, scontext, scontext_len,
                                            sid, SECSID_NULL, gfp, 0);
}

int security_context_str_to_sid(struct selinux_state *state,
                                const char *scontext, u32 *sid, gfp_t gfp)
{
        return security_context_to_sid(state, scontext, strlen(scontext),
                                       sid, gfp);
}

/**
 * security_context_to_sid_default - Obtain a SID for a given security context,
 * falling back to specified default if needed.
 *
 * @state: SELinux state
 * @scontext: security context
 * @scontext_len: length in bytes
 * @sid: security identifier, SID
 * @def_sid: default SID to assign on error
 *
 * Obtains a SID associated with the security context that
 * has the string representation specified by @scontext.
 * The default SID is passed to the MLS layer to be used to allow
 * kernel labeling of the MLS field if the MLS field is not present
 * (for upgrading to MLS without full relabel).
 * Implicitly forces adding of the context even if it cannot be mapped yet.
 * Returns -%EINVAL if the context is invalid, -%ENOMEM if insufficient
 * memory is available, or 0 on success.
 */
int security_context_to_sid_default(struct selinux_state *state,
                                    const char *scontext, u32 scontext_len,
                                    u32 *sid, u32 def_sid, gfp_t gfp_flags)
{
        return security_context_to_sid_core(state, scontext, scontext_len,
                                            sid, def_sid, gfp_flags, 1);
}

int security_context_to_sid_force(struct selinux_state *state,
                                  const char *scontext, u32 scontext_len,
                                  u32 *sid)
{
        return security_context_to_sid_core(state, scontext, scontext_len,
                                            sid, SECSID_NULL, GFP_KERNEL, 1);
}

static int compute_sid_handle_invalid_context(
        struct selinux_state *state,
        struct selinux_policy *policy,
        struct sidtab_entry *sentry,
        struct sidtab_entry *tentry,
        u16 tclass,
        struct context *newcontext)
{
        struct policydb *policydb = &policy->policydb;
        struct sidtab *sidtab = policy->sidtab;
        char *s = NULL, *t = NULL, *n = NULL;
        u32 slen, tlen, nlen;
        struct audit_buffer *ab;

        if (sidtab_entry_to_string(policydb, sidtab, sentry, &s, &slen))
                goto out;
        if (sidtab_entry_to_string(policydb, sidtab, tentry, &t, &tlen))
                goto out;
        if (context_struct_to_string(policydb, newcontext, &n, &nlen))
                goto out;
        ab = audit_log_start(audit_context(), GFP_ATOMIC, AUDIT_SELINUX_ERR);
        audit_log_format(ab,
                         "op=security_compute_sid invalid_context=");
        /* no need to record the NUL with untrusted strings */
        audit_log_n_untrustedstring(ab, n, nlen - 1);
        audit_log_format(ab, " scontext=%s tcontext=%s tclass=%s",
                         s, t, sym_name(policydb, SYM_CLASSES, tclass-1));
        audit_log_end(ab);
out:
        kfree(s);
        kfree(t);
        kfree(n);
        if (!enforcing_enabled(state))
                return 0;
        return -EACCES;
}

static void filename_compute_type(struct policydb *policydb,
                                  struct context *newcontext,
                                  u32 stype, u32 ttype, u16 tclass,
                                  const char *objname)
{
        struct filename_trans_key ft;
        struct filename_trans_datum *datum;

        /*
         * Most filename trans rules are going to live in specific directories
         * like /dev or /var/run.  This bitmap will quickly skip rule searches
         * if the ttype does not contain any rules.
         */
        if (!ebitmap_get_bit(&policydb->filename_trans_ttypes, ttype))
                return;

        ft.ttype = ttype;
        ft.tclass = tclass;
        ft.name = objname;

        datum = policydb_filenametr_search(policydb, &ft);
        while (datum) {
                if (ebitmap_get_bit(&datum->stypes, stype - 1)) {
                        newcontext->type = datum->otype;
                        return;
                }
                datum = datum->next;
        }
}

static int security_compute_sid(struct selinux_state *state,
                                u32 ssid,
                                u32 tsid,
                                u16 orig_tclass,
                                u32 specified,
                                const char *objname,
                                u32 *out_sid,
                                bool kern)
{
        struct selinux_policy *policy;
        struct policydb *policydb;
        struct sidtab *sidtab;
        struct class_datum *cladatum;
        struct context *scontext, *tcontext, newcontext;
        struct sidtab_entry *sentry, *tentry;
        struct avtab_key avkey;
        struct avtab_datum *avdatum;
        struct avtab_node *node;
        u16 tclass;
        int rc = 0;
        bool sock;

        if (!selinux_initialized(state)) {
                switch (orig_tclass) {
                case SECCLASS_PROCESS: /* kernel value */
                        *out_sid = ssid;
                        break;
                default:
                        *out_sid = tsid;
                        break;
                }
                goto out;
        }

retry:
        cladatum = NULL;
        context_init(&newcontext);

        rcu_read_lock();

        policy = rcu_dereference(state->policy);

        if (kern) {
                tclass = unmap_class(&policy->map, orig_tclass);
                sock = security_is_socket_class(orig_tclass);
        } else {
                tclass = orig_tclass;
                sock = security_is_socket_class(map_class(&policy->map,
                                                          tclass));
        }

        policydb = &policy->policydb;
        sidtab = policy->sidtab;

        sentry = sidtab_search_entry(sidtab, ssid);
        if (!sentry) {
                pr_err("SELinux: %s:  unrecognized SID %d\n",
                       __func__, ssid);
                rc = -EINVAL;
                goto out_unlock;
        }
        tentry = sidtab_search_entry(sidtab, tsid);
        if (!tentry) {
                pr_err("SELinux: %s:  unrecognized SID %d\n",
                       __func__, tsid);
                rc = -EINVAL;
                goto out_unlock;
        }

        scontext = &sentry->context;
        tcontext = &tentry->context;

        if (tclass && tclass <= policydb->p_classes.nprim)
                cladatum = policydb->class_val_to_struct[tclass - 1];

        /* Set the user identity. */
        switch (specified) {
        case AVTAB_TRANSITION:
        case AVTAB_CHANGE:
                if (cladatum && cladatum->default_user == DEFAULT_TARGET) {
                        newcontext.user = tcontext->user;
                } else {
                        /* notice this gets both DEFAULT_SOURCE and unset */
                        /* Use the process user identity. */
                        newcontext.user = scontext->user;
                }
                break;
        case AVTAB_MEMBER:
                /* Use the related object owner. */
                newcontext.user = tcontext->user;
                break;
        }

        /* Set the role to default values. */
        if (cladatum && cladatum->default_role == DEFAULT_SOURCE) {
                newcontext.role = scontext->role;
        } else if (cladatum && cladatum->default_role == DEFAULT_TARGET) {
                newcontext.role = tcontext->role;
        } else {
                if ((tclass == policydb->process_class) || sock)
                        newcontext.role = scontext->role;
                else
                        newcontext.role = OBJECT_R_VAL;
        }

        /* Set the type to default values. */
        if (cladatum && cladatum->default_type == DEFAULT_SOURCE) {
                newcontext.type = scontext->type;
        } else if (cladatum && cladatum->default_type == DEFAULT_TARGET) {
                newcontext.type = tcontext->type;
        } else {
                if ((tclass == policydb->process_class) || sock) {
                        /* Use the type of process. */
                        newcontext.type = scontext->type;
                } else {
                        /* Use the type of the related object. */
                        newcontext.type = tcontext->type;
                }
        }

        /* Look for a type transition/member/change rule. */
        avkey.source_type = scontext->type;
        avkey.target_type = tcontext->type;
        avkey.target_class = tclass;
        avkey.specified = specified;
        avdatum = avtab_search(&policydb->te_avtab, &avkey);

        /* If no permanent rule, also check for enabled conditional rules */
        if (!avdatum) {
                node = avtab_search_node(&policydb->te_cond_avtab, &avkey);
                for (; node; node = avtab_search_node_next(node, specified)) {
                        if (node->key.specified & AVTAB_ENABLED) {
                                avdatum = &node->datum;
                                break;
                        }
                }
        }

        if (avdatum) {
                /* Use the type from the type transition/member/change rule. */
                newcontext.type = avdatum->u.data;
        }

        /* if we have a objname this is a file trans check so check those rules */
        if (objname)
                filename_compute_type(policydb, &newcontext, scontext->type,
                                      tcontext->type, tclass, objname);

        /* Check for class-specific changes. */
        if (specified & AVTAB_TRANSITION) {
                /* Look for a role transition rule. */
                struct role_trans_datum *rtd;
                struct role_trans_key rtk = {
                        .role = scontext->role,
                        .type = tcontext->type,
                        .tclass = tclass,
                };

                rtd = policydb_roletr_search(policydb, &rtk);
                if (rtd)
                        newcontext.role = rtd->new_role;
        }

        /* Set the MLS attributes.
           This is done last because it may allocate memory. */
        rc = mls_compute_sid(policydb, scontext, tcontext, tclass, specified,
                             &newcontext, sock);
        if (rc)
                goto out_unlock;

        /* Check the validity of the context. */
        if (!policydb_context_isvalid(policydb, &newcontext)) {
                rc = compute_sid_handle_invalid_context(state, policy, sentry,
                                                        tentry, tclass,
                                                        &newcontext);
                if (rc)
                        goto out_unlock;
        }
        /* Obtain the sid for the context. */
        rc = sidtab_context_to_sid(sidtab, &newcontext, out_sid);
        if (rc == -ESTALE) {
                rcu_read_unlock();
                context_destroy(&newcontext);
                goto retry;
        }
out_unlock:
        rcu_read_unlock();
        context_destroy(&newcontext);
out:
        return rc;
}

/**
 * security_transition_sid - Compute the SID for a new subject/object.
 * @state: SELinux state
 * @ssid: source security identifier
 * @tsid: target security identifier
 * @tclass: target security class
 * @out_sid: security identifier for new subject/object
 *
 * Compute a SID to use for labeling a new subject or object in the
 * class @tclass based on a SID pair (@ssid, @tsid).
 * Return -%EINVAL if any of the parameters are invalid, -%ENOMEM
 * if insufficient memory is available, or %0 if the new SID was
 * computed successfully.
 */
int security_transition_sid(struct selinux_state *state,
                            u32 ssid, u32 tsid, u16 tclass,
                            const struct qstr *qstr, u32 *out_sid)
{
        return security_compute_sid(state, ssid, tsid, tclass,
                                    AVTAB_TRANSITION,
                                    qstr ? qstr->name : NULL, out_sid, true);
}

int security_transition_sid_user(struct selinux_state *state,
                                 u32 ssid, u32 tsid, u16 tclass,
                                 const char *objname, u32 *out_sid)
{
        return security_compute_sid(state, ssid, tsid, tclass,
                                    AVTAB_TRANSITION,
                                    objname, out_sid, false);
}

/**
 * security_member_sid - Compute the SID for member selection.
 * @ssid: source security identifier
 * @tsid: target security identifier
 * @tclass: target security class
 * @out_sid: security identifier for selected member
 *
 * Compute a SID to use when selecting a member of a polyinstantiated
 * object of class @tclass based on a SID pair (@ssid, @tsid).
 * Return -%EINVAL if any of the parameters are invalid, -%ENOMEM
 * if insufficient memory is available, or %0 if the SID was
 * computed successfully.
 */
int security_member_sid(struct selinux_state *state,
                        u32 ssid,
                        u32 tsid,
                        u16 tclass,
                        u32 *out_sid)
{
        return security_compute_sid(state, ssid, tsid, tclass,
                                    AVTAB_MEMBER, NULL,
                                    out_sid, false);
}

/**
 * security_change_sid - Compute the SID for object relabeling.
 * @state: SELinux state
 * @ssid: source security identifier
 * @tsid: target security identifier
 * @tclass: target security class
 * @out_sid: security identifier for selected member
 *
 * Compute a SID to use for relabeling an object of class @tclass
 * based on a SID pair (@ssid, @tsid).
 * Return -%EINVAL if any of the parameters are invalid, -%ENOMEM
 * if insufficient memory is available, or %0 if the SID was
 * computed successfully.
 */
int security_change_sid(struct selinux_state *state,
                        u32 ssid,
                        u32 tsid,
                        u16 tclass,
                        u32 *out_sid)
{
        return security_compute_sid(state,
                                    ssid, tsid, tclass, AVTAB_CHANGE, NULL,
                                    out_sid, false);
}

static inline int convert_context_handle_invalid_context(
        struct selinux_state *state,
        struct policydb *policydb,
        struct context *context)
{
        char *s;