diff options
Diffstat (limited to 'security/selinux/ss/mls.c')
| -rw-r--r-- | security/selinux/ss/mls.c | 527 |
1 files changed, 527 insertions, 0 deletions
diff --git a/security/selinux/ss/mls.c b/security/selinux/ss/mls.c new file mode 100644 index 00000000000..756036bcc24 --- /dev/null +++ b/security/selinux/ss/mls.c @@ -0,0 +1,527 @@ +/* + * 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) 2004-2005 Trusted Computer Solutions, Inc. + */ + +#include <linux/kernel.h> +#include <linux/slab.h> +#include <linux/string.h> +#include <linux/errno.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, range; + + if (!selinux_mls_enabled) + return 0; + + len = 1; /* for the beginning ":" */ + for (l = 0; l < 2; l++) { + range = 0; + len += strlen(policydb.p_sens_val_to_name[context->range.level[l].sens - 1]); + + for (i = 1; i <= ebitmap_length(&context->range.level[l].cat); i++) { + if (ebitmap_get_bit(&context->range.level[l].cat, i - 1)) { + if (range) { + range++; + continue; + } + + len += strlen(policydb.p_cat_val_to_name[i - 1]) + 1; + range++; + } else { + if (range > 1) + len += strlen(policydb.p_cat_val_to_name[i - 2]) + 1; + range = 0; + } + } + /* Handle case where last category is the end of range */ + if (range > 1) + len += strlen(policydb.p_cat_val_to_name[i - 2]) + 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; + int i, l, range, wrote_sep; + + if (!selinux_mls_enabled) + return; + + scontextp = *scontext; + + *scontextp = ':'; + scontextp++; + + for (l = 0; l < 2; l++) { + range = 0; + wrote_sep = 0; + strcpy(scontextp, + policydb.p_sens_val_to_name[context->range.level[l].sens - 1]); + scontextp += strlen(policydb.p_sens_val_to_name[context->range.level[l].sens - 1]); + + /* categories */ + for (i = 1; i <= ebitmap_length(&context->range.level[l].cat); i++) { + if (ebitmap_get_bit(&context->range.level[l].cat, i - 1)) { + if (range) { + range++; + continue; + } + + if (!wrote_sep) { + *scontextp++ = ':'; + wrote_sep = 1; + } else + *scontextp++ = ','; + strcpy(scontextp, policydb.p_cat_val_to_name[i - 1]); + scontextp += strlen(policydb.p_cat_val_to_name[i - 1]); + range++; + } else { + if (range > 1) { + if (range > 2) + *scontextp++ = '.'; + else + *scontextp++ = ','; + + strcpy(scontextp, policydb.p_cat_val_to_name[i - 2]); + scontextp += strlen(policydb.p_cat_val_to_name[i - 2]); + } + range = 0; + } + } + + /* Handle case where last category is the end of range */ + if (range > 1) { + if (range > 2) + *scontextp++ = '.'; + else + *scontextp++ = ','; + + strcpy(scontextp, policydb.p_cat_val_to_name[i - 2]); + scontextp += strlen(policydb.p_cat_val_to_name[i - 2]); + } + + if (l == 0) { + if (mls_level_eq(&context->range.level[0], + &context->range.level[1])) + break; + else { + *scontextp = '-'; + scontextp++; + } + } + } + + *scontext = scontextp; + return; +} + +/* + * 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 level_datum *levdatum; + struct user_datum *usrdatum; + int i, l; + + if (!selinux_mls_enabled) + return 1; + + /* + * MLS range validity checks: high must dominate low, low level must + * be valid (category set <-> sensitivity check), and high level must + * be valid (category set <-> sensitivity check) + */ + if (!mls_level_dom(&c->range.level[1], &c->range.level[0])) + /* High does not dominate low. */ + return 0; + + for (l = 0; l < 2; l++) { + if (!c->range.level[l].sens || c->range.level[l].sens > p->p_levels.nprim) + return 0; + levdatum = hashtab_search(p->p_levels.table, + p->p_sens_val_to_name[c->range.level[l].sens - 1]); + if (!levdatum) + return 0; + + for (i = 1; i <= ebitmap_length(&c->range.level[l].cat); i++) { + if (ebitmap_get_bit(&c->range.level[l].cat, i - 1)) { + if (i > p->p_cats.nprim) + return 0; + if (!ebitmap_get_bit(&levdatum->level->cat, i - 1)) + /* + * Category may not be associated with + * sensitivity in low level. + */ + 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. + */ +int mls_context_to_sid(char oldc, + char **scontext, + struct context *context) +{ + + char delim; + char *scontextp, *p, *rngptr; + struct level_datum *levdatum; + struct cat_datum *catdatum, *rngdatum; + int l, rc = -EINVAL; + + if (!selinux_mls_enabled) + return 0; + + /* No MLS component to the security context. */ + if (!oldc) + 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(policydb.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 */ + if ((rngptr = strchr(scontextp, '.')) != NULL) { + /* Remove '.' */ + *rngptr++ = 0; + } + + catdatum = hashtab_search(policydb.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(policydb.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; +} + +/* + * Copies the MLS range from `src' into `dst'. + */ +static inline int mls_copy_context(struct context *dst, + struct context *src) +{ + int l, rc = 0; + + /* Copy the MLS range from the source context */ + for (l = 0; l < 2; l++) { + dst->range.level[l].sens = src->range.level[l].sens; + rc = ebitmap_cpy(&dst->range.level[l].cat, + &src->range.level[l].cat); + if (rc) + break; + } + + return rc; +} + +/* + * Copies the effective MLS range from `src' into `dst'. + */ +static inline int mls_scopy_context(struct context *dst, + struct context *src) +{ + int l, rc = 0; + + /* Copy the MLS range from the source context */ + for (l = 0; l < 2; l++) { + dst->range.level[l].sens = src->range.level[0].sens; + rc = ebitmap_cpy(&dst->range.level[l].cat, + &src->range.level[0].cat); + if (rc) + break; + } + + return rc; +} + +/* + * Copies the MLS range `range' into `context'. + */ +static inline 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 (selinux_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; + int l, i; + + if (!selinux_mls_enabled) + return 0; + + for (l = 0; l < 2; l++) { + levdatum = hashtab_search(newp->p_levels.table, + oldp->p_sens_val_to_name[c->range.level[l].sens - 1]); + + if (!levdatum) + return -EINVAL; + c->range.level[l].sens = levdatum->level->sens; + + ebitmap_init(&bitmap); + for (i = 1; i <= ebitmap_length(&c->range.level[l].cat); i++) { + if (ebitmap_get_bit(&c->range.level[l].cat, i - 1)) { + int rc; + + catdatum = hashtab_search(newp->p_cats.table, + oldp->p_cat_val_to_name[i - 1]); + if (!catdatum) + return -EINVAL; + rc = ebitmap_set_bit(&bitmap, catdatum->value - 1, 1); + if (rc) + return rc; + } + } + 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) +{ + if (!selinux_mls_enabled) + return 0; + + switch (specified) { + case AVTAB_TRANSITION: + if (tclass == SECCLASS_PROCESS) { + struct range_trans *rangetr; + /* Look for a range transition rule. */ + for (rangetr = policydb.range_tr; rangetr; + rangetr = rangetr->next) { + if (rangetr->dom == scontext->type && + rangetr->type == tcontext->type) { + /* Set the range from the rule */ + return mls_range_set(newcontext, + &rangetr->range); + } + } + } + /* Fallthrough */ + case AVTAB_CHANGE: + if (tclass == SECCLASS_PROCESS) + /* Use the process MLS attributes. */ + return mls_copy_context(newcontext, scontext); + else + /* Use the process effective MLS attributes. */ + return mls_scopy_context(newcontext, scontext); + case AVTAB_MEMBER: + /* Only polyinstantiate the MLS attributes if + the type is being polyinstantiated */ + if (newcontext->type != tcontext->type) { + /* Use the process effective MLS attributes. */ + return mls_scopy_context(newcontext, scontext); + } else { + /* Use the related object MLS attributes. */ + return mls_copy_context(newcontext, tcontext); + } + default: + return -EINVAL; + } + return -EINVAL; +} + |