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linux/security/selinux/ss/mls.c
Linus Torvalds 1da177e4c3 Linux-2.6.12-rc2 
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00

528 lines
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/*
* 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;
}
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