From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- security/selinux/ss/mls.c | 668 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 668 insertions(+) create mode 100644 security/selinux/ss/mls.c (limited to 'security/selinux/ss/mls.c') diff --git a/security/selinux/ss/mls.c b/security/selinux/ss/mls.c new file mode 100644 index 000000000..e10888422 --- /dev/null +++ b/security/selinux/ss/mls.c @@ -0,0 +1,668 @@ +/* + * Implementation of the multi-level security (MLS) policy. + * + * Author : Stephen Smalley, + */ +/* + * Updated: Trusted Computer Solutions, Inc. + * + * Support for enhanced MLS infrastructure. + * + * Copyright (C) 2004-2006 Trusted Computer Solutions, Inc. + */ +/* + * Updated: Hewlett-Packard + * + * Added support to import/export the MLS label from NetLabel + * + * (c) Copyright Hewlett-Packard Development Company, L.P., 2006 + */ + +#include +#include +#include +#include +#include +#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 */ -- cgit v1.2.3-54-g00ecf