int avtab_read_item(void *fp, struct avtab_datum *avdatum, struct avtab_key *avkey)
{
__u32 *buf;
__u32 items, items2;
memset(avkey, 0, sizeof(struct avtab_key));
memset(avdatum, 0, sizeof(struct avtab_datum));
buf = next_entry(fp, sizeof(__u32));
if (!buf) {
printk(KERN_ERR "security: avtab: truncated entry\n");
goto bad;
}
items2 = le32_to_cpu(buf[0]);
buf = next_entry(fp, sizeof(__u32)*items2);
if (!buf) {
printk(KERN_ERR "security: avtab: truncated entry\n");
goto bad;
}
items = 0;
avkey->source_type = le32_to_cpu(buf[items++]);
avkey->target_type = le32_to_cpu(buf[items++]);
avkey->target_class = le32_to_cpu(buf[items++]);
avdatum->specified = le32_to_cpu(buf[items++]);
if (!(avdatum->specified & (AVTAB_AV | AVTAB_TYPE))) {
printk(KERN_ERR "security: avtab: null entry\n");
goto bad;
}
if ((avdatum->specified & AVTAB_AV) &&
(avdatum->specified & AVTAB_TYPE)) {
printk(KERN_ERR "security: avtab: entry has both access vectors and types\n");
goto bad;
}
if (avdatum->specified & AVTAB_AV) {
if (avdatum->specified & AVTAB_ALLOWED)
avtab_allowed(avdatum) = le32_to_cpu(buf[items++]);
if (avdatum->specified & AVTAB_AUDITDENY)
avtab_auditdeny(avdatum) = le32_to_cpu(buf[items++]);
if (avdatum->specified & AVTAB_AUDITALLOW)
avtab_auditallow(avdatum) = le32_to_cpu(buf[items++]);
} else {
if (avdatum->specified & AVTAB_TRANSITION)
avtab_transition(avdatum) = le32_to_cpu(buf[items++]);
if (avdatum->specified & AVTAB_CHANGE)
avtab_change(avdatum) = le32_to_cpu(buf[items++]);
if (avdatum->specified & AVTAB_MEMBER)
avtab_member(avdatum) = le32_to_cpu(buf[items++]);
}
if (items != items2) {
printk(KERN_ERR "security: avtab: entry only had %d items, expected %d\n",
items2, items);
goto bad;
}
return 0;
bad:
return -1;
}
static int security_compute_sid(u32 ssid,
u32 tsid,
u16 tclass,
u32 specified,
u32 *out_sid)
{
struct context *scontext = 0, *tcontext = 0, newcontext;
struct role_trans *roletr = 0;
struct avtab_key avkey;
struct avtab_datum *avdatum;
unsigned int type_change = 0;
int rc = 0;
if (!ss_initialized) {
switch (tclass) {
case SECCLASS_PROCESS:
*out_sid = ssid;
break;
default:
*out_sid = tsid;
break;
}
goto out;
}
POLICY_RDLOCK;
scontext = sidtab_search(&sidtab, ssid);
if (!scontext) {
printk(KERN_ERR "security_compute_sid: unrecognized SID %d\n",
ssid);
rc = -EINVAL;
goto out_unlock;
}
tcontext = sidtab_search(&sidtab, tsid);
if (!tcontext) {
printk(KERN_ERR "security_compute_sid: unrecognized SID %d\n",
tsid);
rc = -EINVAL;
goto out_unlock;
}
context_init(&newcontext);
/* Set the user identity. */
switch (specified) {
case AVTAB_TRANSITION:
case AVTAB_CHANGE:
/* 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 and type to default values. */
switch (tclass) {
case SECCLASS_PROCESS:
/* Use the current role and type of process. */
newcontext.role = scontext->role;
newcontext.type = scontext->type;
break;
default:
/* Use the well-defined object role. */
newcontext.role = OBJECT_R_VAL;
/* 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;
avdatum = avtab_search(&policydb.te_avtab, &avkey, AVTAB_TYPE);
type_change = (avdatum && (avdatum->specified & specified));
if (type_change) {
/* Use the type from the type transition/member/change rule. */
switch (specified) {
case AVTAB_TRANSITION:
newcontext.type = avtab_transition(avdatum);
break;
case AVTAB_MEMBER:
newcontext.type = avtab_member(avdatum);
break;
case AVTAB_CHANGE:
newcontext.type = avtab_change(avdatum);
break;
}
}
/* Check for class-specific changes. */
switch (tclass) {
case SECCLASS_PROCESS:
if (specified & AVTAB_TRANSITION) {
/* Look for a role transition rule. */
for (roletr = policydb.role_tr; roletr;
roletr = roletr->next) {
if (roletr->role == scontext->role &&
roletr->type == tcontext->type) {
/* Use the role transition rule. */
newcontext.role = roletr->new_role;
break;
}
}
}
if (!type_change && !roletr) {
/* No change in process role or type. */
*out_sid = ssid;
goto out_unlock;
}
break;
default:
if (!type_change &&
(newcontext.user == tcontext->user) &&
mls_context_cmp(scontext, tcontext)) {
/* No change in object type, owner,
or MLS attributes. */
*out_sid = tsid;
goto out_unlock;
}
break;
}
/* Set the MLS attributes.
This is done last because it may allocate memory. */
rc = mls_compute_sid(scontext, tcontext, tclass, specified, &newcontext);
if (rc)
goto out_unlock;
/* Check the validity of the context. */
if (!policydb_context_isvalid(&policydb, &newcontext)) {
rc = compute_sid_handle_invalid_context(scontext,
tcontext,
tclass,
&newcontext);
if (rc)
goto out_unlock;
}
/* Obtain the sid for the context. */
rc = sidtab_context_to_sid(&sidtab, &newcontext, out_sid);
out_unlock:
POLICY_RDUNLOCK;
context_destroy(&newcontext);
out:
return rc;
}
