--- /dev/null
+/*
+ * Implementation of the multi-level security (MLS) policy.
+ *
+ * Author : Stephen Smalley, <sds@epoch.ncsc.mil>
+ */
+/*
+ * Updated: Trusted Computer Solutions, Inc. <dgoeddel@trustedcs.com>
+ *
+ * Support for enhanced MLS infrastructure.
+ *
+ * Copyright (C) 2004-2006 Trusted Computer Solutions, Inc.
+ */
+/*
+ * Updated: Hewlett-Packard <paul@paul-moore.com>
+ *
+ * Added support to import/export the MLS label from NetLabel
+ *
+ * (c) Copyright Hewlett-Packard Development Company, L.P., 2006
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <net/netlabel.h>
+#include "sidtab.h"
+#include "mls.h"
+#include "policydb.h"
+#include "services.h"
+
+/*
+ * Return the length in bytes for the MLS fields of the
+ * security context string representation of `context'.
+ */
+int mls_compute_context_len(struct context *context)
+{
+ int i, l, len, head, prev;
+ char *nm;
+ struct ebitmap *e;
+ struct ebitmap_node *node;
+
+ if (!policydb.mls_enabled)
+ return 0;
+
+ len = 1; /* for the beginning ":" */
+ for (l = 0; l < 2; l++) {
+ int index_sens = context->range.level[l].sens;
+ len += strlen(sym_name(&policydb, SYM_LEVELS, index_sens - 1));
+
+ /* categories */
+ head = -2;
+ prev = -2;
+ e = &context->range.level[l].cat;
+ ebitmap_for_each_positive_bit(e, node, i) {
+ if (i - prev > 1) {
+ /* one or more negative bits are skipped */
+ if (head != prev) {
+ nm = sym_name(&policydb, SYM_CATS, prev);
+ len += strlen(nm) + 1;
+ }
+ nm = sym_name(&policydb, SYM_CATS, i);
+ len += strlen(nm) + 1;
+ head = i;
+ }
+ prev = i;
+ }
+ if (prev != head) {
+ nm = sym_name(&policydb, SYM_CATS, prev);
+ len += strlen(nm) + 1;
+ }
+ if (l == 0) {
+ if (mls_level_eq(&context->range.level[0],
+ &context->range.level[1]))
+ break;
+ else
+ len++;
+ }
+ }
+
+ return len;
+}
+
+/*
+ * Write the security context string representation of
+ * the MLS fields of `context' into the string `*scontext'.
+ * Update `*scontext' to point to the end of the MLS fields.
+ */
+void mls_sid_to_context(struct context *context,
+ char **scontext)
+{
+ char *scontextp, *nm;
+ int i, l, head, prev;
+ struct ebitmap *e;
+ struct ebitmap_node *node;
+
+ if (!policydb.mls_enabled)
+ return;
+
+ scontextp = *scontext;
+
+ *scontextp = ':';
+ scontextp++;
+
+ for (l = 0; l < 2; l++) {
+ strcpy(scontextp, sym_name(&policydb, SYM_LEVELS,
+ context->range.level[l].sens - 1));
+ scontextp += strlen(scontextp);
+
+ /* categories */
+ head = -2;
+ prev = -2;
+ e = &context->range.level[l].cat;
+ ebitmap_for_each_positive_bit(e, node, i) {
+ if (i - prev > 1) {
+ /* one or more negative bits are skipped */
+ if (prev != head) {
+ if (prev - head > 1)
+ *scontextp++ = '.';
+ else
+ *scontextp++ = ',';
+ nm = sym_name(&policydb, SYM_CATS, prev);
+ strcpy(scontextp, nm);
+ scontextp += strlen(nm);
+ }
+ if (prev < 0)
+ *scontextp++ = ':';
+ else
+ *scontextp++ = ',';
+ nm = sym_name(&policydb, SYM_CATS, i);
+ strcpy(scontextp, nm);
+ scontextp += strlen(nm);
+ head = i;
+ }
+ prev = i;
+ }
+
+ if (prev != head) {
+ if (prev - head > 1)
+ *scontextp++ = '.';
+ else
+ *scontextp++ = ',';
+ nm = sym_name(&policydb, SYM_CATS, prev);
+ strcpy(scontextp, nm);
+ scontextp += strlen(nm);
+ }
+
+ if (l == 0) {
+ if (mls_level_eq(&context->range.level[0],
+ &context->range.level[1]))
+ break;
+ else
+ *scontextp++ = '-';
+ }
+ }
+
+ *scontext = scontextp;
+ return;
+}
+
+int mls_level_isvalid(struct policydb *p, struct mls_level *l)
+{
+ struct level_datum *levdatum;
+
+ if (!l->sens || l->sens > p->p_levels.nprim)
+ return 0;
+ levdatum = hashtab_search(p->p_levels.table,
+ sym_name(p, SYM_LEVELS, l->sens - 1));
+ if (!levdatum)
+ return 0;
+
+ /*
+ * Return 1 iff all the bits set in l->cat are also be set in
+ * levdatum->level->cat and no bit in l->cat is larger than
+ * p->p_cats.nprim.
+ */
+ return ebitmap_contains(&levdatum->level->cat, &l->cat,
+ p->p_cats.nprim);
+}
+
+int mls_range_isvalid(struct policydb *p, struct mls_range *r)
+{
+ return (mls_level_isvalid(p, &r->level[0]) &&
+ mls_level_isvalid(p, &r->level[1]) &&
+ mls_level_dom(&r->level[1], &r->level[0]));
+}
+
+/*
+ * Return 1 if the MLS fields in the security context
+ * structure `c' are valid. Return 0 otherwise.
+ */
+int mls_context_isvalid(struct policydb *p, struct context *c)
+{
+ struct user_datum *usrdatum;
+
+ if (!p->mls_enabled)
+ return 1;
+
+ if (!mls_range_isvalid(p, &c->range))
+ return 0;
+
+ if (c->role == OBJECT_R_VAL)
+ return 1;
+
+ /*
+ * User must be authorized for the MLS range.
+ */
+ if (!c->user || c->user > p->p_users.nprim)
+ return 0;
+ usrdatum = p->user_val_to_struct[c->user - 1];
+ if (!mls_range_contains(usrdatum->range, c->range))
+ return 0; /* user may not be associated with range */
+
+ return 1;
+}
+
+/*
+ * Set the MLS fields in the security context structure
+ * `context' based on the string representation in
+ * the string `*scontext'. Update `*scontext' to
+ * point to the end of the string representation of
+ * the MLS fields.
+ *
+ * This function modifies the string in place, inserting
+ * NULL characters to terminate the MLS fields.
+ *
+ * If a def_sid is provided and no MLS field is present,
+ * copy the MLS field of the associated default context.
+ * Used for upgraded to MLS systems where objects may lack
+ * MLS fields.
+ *
+ * Policy read-lock must be held for sidtab lookup.
+ *
+ */
+int mls_context_to_sid(struct policydb *pol,
+ char oldc,
+ char **scontext,
+ struct context *context,
+ struct sidtab *s,
+ u32 def_sid)
+{
+
+ char delim;
+ char *scontextp, *p, *rngptr;
+ struct level_datum *levdatum;
+ struct cat_datum *catdatum, *rngdatum;
+ int l, rc = -EINVAL;
+
+ if (!pol->mls_enabled) {
+ if (def_sid != SECSID_NULL && oldc)
+ *scontext += strlen(*scontext) + 1;
+ return 0;
+ }
+
+ /*
+ * No MLS component to the security context, try and map to
+ * default if provided.
+ */
+ if (!oldc) {
+ struct context *defcon;
+
+ if (def_sid == SECSID_NULL)
+ goto out;
+
+ defcon = sidtab_search(s, def_sid);
+ if (!defcon)
+ goto out;
+
+ rc = mls_context_cpy(context, defcon);
+ goto out;
+ }
+
+ /* Extract low sensitivity. */
+ scontextp = p = *scontext;
+ while (*p && *p != ':' && *p != '-')
+ p++;
+
+ delim = *p;
+ if (delim != '\0')
+ *p++ = '\0';
+
+ for (l = 0; l < 2; l++) {
+ levdatum = hashtab_search(pol->p_levels.table, scontextp);
+ if (!levdatum) {
+ rc = -EINVAL;
+ goto out;
+ }
+
+ context->range.level[l].sens = levdatum->level->sens;
+
+ if (delim == ':') {
+ /* Extract category set. */
+ while (1) {
+ scontextp = p;
+ while (*p && *p != ',' && *p != '-')
+ p++;
+ delim = *p;
+ if (delim != '\0')
+ *p++ = '\0';
+
+ /* Separate into range if exists */
+ rngptr = strchr(scontextp, '.');
+ if (rngptr != NULL) {
+ /* Remove '.' */
+ *rngptr++ = '\0';
+ }
+
+ catdatum = hashtab_search(pol->p_cats.table,
+ scontextp);
+ if (!catdatum) {
+ rc = -EINVAL;
+ goto out;
+ }
+
+ rc = ebitmap_set_bit(&context->range.level[l].cat,
+ catdatum->value - 1, 1);
+ if (rc)
+ goto out;
+
+ /* If range, set all categories in range */
+ if (rngptr) {
+ int i;
+
+ rngdatum = hashtab_search(pol->p_cats.table, rngptr);
+ if (!rngdatum) {
+ rc = -EINVAL;
+ goto out;
+ }
+
+ if (catdatum->value >= rngdatum->value) {
+ rc = -EINVAL;
+ goto out;
+ }
+
+ for (i = catdatum->value; i < rngdatum->value; i++) {
+ rc = ebitmap_set_bit(&context->range.level[l].cat, i, 1);
+ if (rc)
+ goto out;
+ }
+ }
+
+ if (delim != ',')
+ break;
+ }
+ }
+ if (delim == '-') {
+ /* Extract high sensitivity. */
+ scontextp = p;
+ while (*p && *p != ':')
+ p++;
+
+ delim = *p;
+ if (delim != '\0')
+ *p++ = '\0';
+ } else
+ break;
+ }
+
+ if (l == 0) {
+ context->range.level[1].sens = context->range.level[0].sens;
+ rc = ebitmap_cpy(&context->range.level[1].cat,
+ &context->range.level[0].cat);
+ if (rc)
+ goto out;
+ }
+ *scontext = ++p;
+ rc = 0;
+out:
+ return rc;
+}
+
+/*
+ * Set the MLS fields in the security context structure
+ * `context' based on the string representation in
+ * the string `str'. This function will allocate temporary memory with the
+ * given constraints of gfp_mask.
+ */
+int mls_from_string(char *str, struct context *context, gfp_t gfp_mask)
+{
+ char *tmpstr, *freestr;
+ int rc;
+
+ if (!policydb.mls_enabled)
+ return -EINVAL;
+
+ /* we need freestr because mls_context_to_sid will change
+ the value of tmpstr */
+ tmpstr = freestr = kstrdup(str, gfp_mask);
+ if (!tmpstr) {
+ rc = -ENOMEM;
+ } else {
+ rc = mls_context_to_sid(&policydb, ':', &tmpstr, context,
+ NULL, SECSID_NULL);
+ kfree(freestr);
+ }
+
+ return rc;
+}
+
+/*
+ * Copies the MLS range `range' into `context'.
+ */
+int mls_range_set(struct context *context,
+ struct mls_range *range)
+{
+ int l, rc = 0;
+
+ /* Copy the MLS range into the context */
+ for (l = 0; l < 2; l++) {
+ context->range.level[l].sens = range->level[l].sens;
+ rc = ebitmap_cpy(&context->range.level[l].cat,
+ &range->level[l].cat);
+ if (rc)
+ break;
+ }
+
+ return rc;
+}
+
+int mls_setup_user_range(struct context *fromcon, struct user_datum *user,
+ struct context *usercon)
+{
+ if (policydb.mls_enabled) {
+ struct mls_level *fromcon_sen = &(fromcon->range.level[0]);
+ struct mls_level *fromcon_clr = &(fromcon->range.level[1]);
+ struct mls_level *user_low = &(user->range.level[0]);
+ struct mls_level *user_clr = &(user->range.level[1]);
+ struct mls_level *user_def = &(user->dfltlevel);
+ struct mls_level *usercon_sen = &(usercon->range.level[0]);
+ struct mls_level *usercon_clr = &(usercon->range.level[1]);
+
+ /* Honor the user's default level if we can */
+ if (mls_level_between(user_def, fromcon_sen, fromcon_clr))
+ *usercon_sen = *user_def;
+ else if (mls_level_between(fromcon_sen, user_def, user_clr))
+ *usercon_sen = *fromcon_sen;
+ else if (mls_level_between(fromcon_clr, user_low, user_def))
+ *usercon_sen = *user_low;
+ else
+ return -EINVAL;
+
+ /* Lower the clearance of available contexts
+ if the clearance of "fromcon" is lower than
+ that of the user's default clearance (but
+ only if the "fromcon" clearance dominates
+ the user's computed sensitivity level) */
+ if (mls_level_dom(user_clr, fromcon_clr))
+ *usercon_clr = *fromcon_clr;
+ else if (mls_level_dom(fromcon_clr, user_clr))
+ *usercon_clr = *user_clr;
+ else
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+/*
+ * Convert the MLS fields in the security context
+ * structure `c' from the values specified in the
+ * policy `oldp' to the values specified in the policy `newp'.
+ */
+int mls_convert_context(struct policydb *oldp,
+ struct policydb *newp,
+ struct context *c)
+{
+ struct level_datum *levdatum;
+ struct cat_datum *catdatum;
+ struct ebitmap bitmap;
+ struct ebitmap_node *node;
+ int l, i;
+
+ if (!policydb.mls_enabled)
+ return 0;
+
+ for (l = 0; l < 2; l++) {
+ levdatum = hashtab_search(newp->p_levels.table,
+ sym_name(oldp, SYM_LEVELS,
+ c->range.level[l].sens - 1));
+
+ if (!levdatum)
+ return -EINVAL;
+ c->range.level[l].sens = levdatum->level->sens;
+
+ ebitmap_init(&bitmap);
+ ebitmap_for_each_positive_bit(&c->range.level[l].cat, node, i) {
+ int rc;
+
+ catdatum = hashtab_search(newp->p_cats.table,
+ sym_name(oldp, SYM_CATS, i));
+ if (!catdatum)
+ return -EINVAL;
+ rc = ebitmap_set_bit(&bitmap, catdatum->value - 1, 1);
+ if (rc)
+ return rc;
+
+ cond_resched();
+ }
+ ebitmap_destroy(&c->range.level[l].cat);
+ c->range.level[l].cat = bitmap;
+ }
+
+ return 0;
+}
+
+int mls_compute_sid(struct context *scontext,
+ struct context *tcontext,
+ u16 tclass,
+ u32 specified,
+ struct context *newcontext,
+ bool sock)
+{
+ struct range_trans rtr;
+ struct mls_range *r;
+ struct class_datum *cladatum;
+ int default_range = 0;
+
+ if (!policydb.mls_enabled)
+ return 0;
+
+ switch (specified) {
+ case AVTAB_TRANSITION:
+ /* Look for a range transition rule. */
+ rtr.source_type = scontext->type;
+ rtr.target_type = tcontext->type;
+ rtr.target_class = tclass;
+ r = hashtab_search(policydb.range_tr, &rtr);
+ if (r)
+ return mls_range_set(newcontext, r);
+
+ if (tclass && tclass <= policydb.p_classes.nprim) {
+ cladatum = policydb.class_val_to_struct[tclass - 1];
+ if (cladatum)
+ default_range = cladatum->default_range;
+ }
+
+ switch (default_range) {
+ case DEFAULT_SOURCE_LOW:
+ return mls_context_cpy_low(newcontext, scontext);
+ case DEFAULT_SOURCE_HIGH:
+ return mls_context_cpy_high(newcontext, scontext);
+ case DEFAULT_SOURCE_LOW_HIGH:
+ return mls_context_cpy(newcontext, scontext);
+ case DEFAULT_TARGET_LOW:
+ return mls_context_cpy_low(newcontext, tcontext);
+ case DEFAULT_TARGET_HIGH:
+ return mls_context_cpy_high(newcontext, tcontext);
+ case DEFAULT_TARGET_LOW_HIGH:
+ return mls_context_cpy(newcontext, tcontext);
+ }
+
+ /* Fallthrough */
+ case AVTAB_CHANGE:
+ if ((tclass == policydb.process_class) || (sock == true))
+ /* Use the process MLS attributes. */
+ return mls_context_cpy(newcontext, scontext);
+ else
+ /* Use the process effective MLS attributes. */
+ return mls_context_cpy_low(newcontext, scontext);
+ case AVTAB_MEMBER:
+ /* Use the process effective MLS attributes. */
+ return mls_context_cpy_low(newcontext, scontext);
+
+ /* fall through */
+ }
+ return -EINVAL;
+}
+
+#ifdef CONFIG_NETLABEL
+/**
+ * mls_export_netlbl_lvl - Export the MLS sensitivity levels to NetLabel
+ * @context: the security context
+ * @secattr: the NetLabel security attributes
+ *
+ * Description:
+ * Given the security context copy the low MLS sensitivity level into the
+ * NetLabel MLS sensitivity level field.
+ *
+ */
+void mls_export_netlbl_lvl(struct context *context,
+ struct netlbl_lsm_secattr *secattr)
+{
+ if (!policydb.mls_enabled)
+ return;
+
+ secattr->attr.mls.lvl = context->range.level[0].sens - 1;
+ secattr->flags |= NETLBL_SECATTR_MLS_LVL;
+}
+
+/**
+ * mls_import_netlbl_lvl - Import the NetLabel MLS sensitivity levels
+ * @context: the security context
+ * @secattr: the NetLabel security attributes
+ *
+ * Description:
+ * Given the security context and the NetLabel security attributes, copy the
+ * NetLabel MLS sensitivity level into the context.
+ *
+ */
+void mls_import_netlbl_lvl(struct context *context,
+ struct netlbl_lsm_secattr *secattr)
+{
+ if (!policydb.mls_enabled)
+ return;
+
+ context->range.level[0].sens = secattr->attr.mls.lvl + 1;
+ context->range.level[1].sens = context->range.level[0].sens;
+}
+
+/**
+ * mls_export_netlbl_cat - Export the MLS categories to NetLabel
+ * @context: the security context
+ * @secattr: the NetLabel security attributes
+ *
+ * Description:
+ * Given the security context copy the low MLS categories into the NetLabel
+ * MLS category field. Returns zero on success, negative values on failure.
+ *
+ */
+int mls_export_netlbl_cat(struct context *context,
+ struct netlbl_lsm_secattr *secattr)
+{
+ int rc;
+
+ if (!policydb.mls_enabled)
+ return 0;
+
+ rc = ebitmap_netlbl_export(&context->range.level[0].cat,
+ &secattr->attr.mls.cat);
+ if (rc == 0 && secattr->attr.mls.cat != NULL)
+ secattr->flags |= NETLBL_SECATTR_MLS_CAT;
+
+ return rc;
+}
+
+/**
+ * mls_import_netlbl_cat - Import the MLS categories from NetLabel
+ * @context: the security context
+ * @secattr: the NetLabel security attributes
+ *
+ * Description:
+ * Copy the NetLabel security attributes into the SELinux context; since the
+ * NetLabel security attribute only contains a single MLS category use it for
+ * both the low and high categories of the context. Returns zero on success,
+ * negative values on failure.
+ *
+ */
+int mls_import_netlbl_cat(struct context *context,
+ struct netlbl_lsm_secattr *secattr)
+{
+ int rc;
+
+ if (!policydb.mls_enabled)
+ return 0;
+
+ rc = ebitmap_netlbl_import(&context->range.level[0].cat,
+ secattr->attr.mls.cat);
+ if (rc)
+ goto import_netlbl_cat_failure;
+ memcpy(&context->range.level[1].cat, &context->range.level[0].cat,
+ sizeof(context->range.level[0].cat));
+
+ return 0;
+
+import_netlbl_cat_failure:
+ ebitmap_destroy(&context->range.level[0].cat);
+ return rc;
+}
+#endif /* CONFIG_NETLABEL */
Code Review / kvmfornfv.git / blobdiff