1 files changed, 696 insertions, 0 deletions

diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c
new file mode 100644
index 000000000..585e5e357
--- /dev/null
+++ b/security/smack/smack_access.c
@@ -0,0 +1,696 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2007 Casey Schaufler <casey@schaufler-ca.com>
+ *
+ * Author:
+ *      Casey Schaufler <casey@schaufler-ca.com>
+ */
+
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/sched.h>
+#include "smack.h"
+
+struct smack_known smack_known_huh = {
+	.smk_known	= "?",
+	.smk_secid	= 2,
+};
+
+struct smack_known smack_known_hat = {
+	.smk_known	= "^",
+	.smk_secid	= 3,
+};
+
+struct smack_known smack_known_star = {
+	.smk_known	= "*",
+	.smk_secid	= 4,
+};
+
+struct smack_known smack_known_floor = {
+	.smk_known	= "_",
+	.smk_secid	= 5,
+};
+
+struct smack_known smack_known_web = {
+	.smk_known	= "@",
+	.smk_secid	= 7,
+};
+
+LIST_HEAD(smack_known_list);
+
+/*
+ * The initial value needs to be bigger than any of the
+ * known values above.
+ */
+static u32 smack_next_secid = 10;
+
+/*
+ * what events do we log
+ * can be overwritten at run-time by /smack/logging
+ */
+int log_policy = SMACK_AUDIT_DENIED;
+
+/**
+ * smk_access_entry - look up matching access rule
+ * @subject_label: a pointer to the subject's Smack label
+ * @object_label: a pointer to the object's Smack label
+ * @rule_list: the list of rules to search
+ *
+ * This function looks up the subject/object pair in the
+ * access rule list and returns the access mode. If no
+ * entry is found returns -ENOENT.
+ *
+ * NOTE:
+ *
+ * Earlier versions of this function allowed for labels that
+ * were not on the label list. This was done to allow for
+ * labels to come over the network that had never been seen
+ * before on this host. Unless the receiving socket has the
+ * star label this will always result in a failure check. The
+ * star labeled socket case is now handled in the networking
+ * hooks so there is no case where the label is not on the
+ * label list. Checking to see if the address of two labels
+ * is the same is now a reliable test.
+ *
+ * Do the object check first because that is more
+ * likely to differ.
+ *
+ * Allowing write access implies allowing locking.
+ */
+int smk_access_entry(char *subject_label, char *object_label,
+			struct list_head *rule_list)
+{
+	struct smack_rule *srp;
+
+	list_for_each_entry_rcu(srp, rule_list, list) {
+		if (srp->smk_object->smk_known == object_label &&
+		    srp->smk_subject->smk_known == subject_label) {
+			int may = srp->smk_access;
+			/*
+			 * MAY_WRITE implies MAY_LOCK.
+			 */
+			if ((may & MAY_WRITE) == MAY_WRITE)
+				may |= MAY_LOCK;
+			return may;
+		}
+	}
+
+	return -ENOENT;
+}
+
+/**
+ * smk_access - determine if a subject has a specific access to an object
+ * @subject: a pointer to the subject's Smack label entry
+ * @object: a pointer to the object's Smack label entry
+ * @request: the access requested, in "MAY" format
+ * @a : a pointer to the audit data
+ *
+ * This function looks up the subject/object pair in the
+ * access rule list and returns 0 if the access is permitted,
+ * non zero otherwise.
+ *
+ * Smack labels are shared on smack_list
+ */
+int smk_access(struct smack_known *subject, struct smack_known *object,
+	       int request, struct smk_audit_info *a)
+{
+	int may = MAY_NOT;
+	int rc = 0;
+
+	/*
+	 * Hardcoded comparisons.
+	 */
+	/*
+	 * A star subject can't access any object.
+	 */
+	if (subject == &smack_known_star) {
+		rc = -EACCES;
+		goto out_audit;
+	}
+	/*
+	 * An internet object can be accessed by any subject.
+	 * Tasks cannot be assigned the internet label.
+	 * An internet subject can access any object.
+	 */
+	if (object == &smack_known_web || subject == &smack_known_web)
+		goto out_audit;
+	/*
+	 * A star object can be accessed by any subject.
+	 */
+	if (object == &smack_known_star)
+		goto out_audit;
+	/*
+	 * An object can be accessed in any way by a subject
+	 * with the same label.
+	 */
+	if (subject->smk_known == object->smk_known)
+		goto out_audit;
+	/*
+	 * A hat subject can read or lock any object.
+	 * A floor object can be read or locked by any subject.
+	 */
+	if ((request & MAY_ANYREAD) == request ||
+	    (request & MAY_LOCK) == request) {
+		if (object == &smack_known_floor)
+			goto out_audit;
+		if (subject == &smack_known_hat)
+			goto out_audit;
+	}
+	/*
+	 * Beyond here an explicit relationship is required.
+	 * If the requested access is contained in the available
+	 * access (e.g. read is included in readwrite) it's
+	 * good. A negative response from smk_access_entry()
+	 * indicates there is no entry for this pair.
+	 */
+	rcu_read_lock();
+	may = smk_access_entry(subject->smk_known, object->smk_known,
+			       &subject->smk_rules);
+	rcu_read_unlock();
+
+	if (may <= 0 || (request & may) != request) {
+		rc = -EACCES;
+		goto out_audit;
+	}
+#ifdef CONFIG_SECURITY_SMACK_BRINGUP
+	/*
+	 * Return a positive value if using bringup mode.
+	 * This allows the hooks to identify checks that
+	 * succeed because of "b" rules.
+	 */
+	if (may & MAY_BRINGUP)
+		rc = SMACK_BRINGUP_ALLOW;
+#endif
+
+out_audit:
+
+#ifdef CONFIG_SECURITY_SMACK_BRINGUP
+	if (rc < 0) {
+		if (object == smack_unconfined)
+			rc = SMACK_UNCONFINED_OBJECT;
+		if (subject == smack_unconfined)
+			rc = SMACK_UNCONFINED_SUBJECT;
+	}
+#endif
+
+#ifdef CONFIG_AUDIT
+	if (a)
+		smack_log(subject->smk_known, object->smk_known,
+			  request, rc, a);
+#endif
+
+	return rc;
+}
+
+/**
+ * smk_tskacc - determine if a task has a specific access to an object
+ * @tsp: a pointer to the subject's task
+ * @obj_known: a pointer to the object's label entry
+ * @mode: the access requested, in "MAY" format
+ * @a : common audit data
+ *
+ * This function checks the subject task's label/object label pair
+ * in the access rule list and returns 0 if the access is permitted,
+ * non zero otherwise. It allows that the task may have the capability
+ * to override the rules.
+ */
+int smk_tskacc(struct task_smack *tsp, struct smack_known *obj_known,
+	       u32 mode, struct smk_audit_info *a)
+{
+	struct smack_known *sbj_known = smk_of_task(tsp);
+	int may;
+	int rc;
+
+	/*
+	 * Check the global rule list
+	 */
+	rc = smk_access(sbj_known, obj_known, mode, NULL);
+	if (rc >= 0) {
+		/*
+		 * If there is an entry in the task's rule list
+		 * it can further restrict access.
+		 */
+		may = smk_access_entry(sbj_known->smk_known,
+				       obj_known->smk_known,
+				       &tsp->smk_rules);
+		if (may < 0)
+			goto out_audit;
+		if ((mode & may) == mode)
+			goto out_audit;
+		rc = -EACCES;
+	}
+
+	/*
+	 * Allow for priviliged to override policy.
+	 */
+	if (rc != 0 && smack_privileged(CAP_MAC_OVERRIDE))
+		rc = 0;
+
+out_audit:
+#ifdef CONFIG_AUDIT
+	if (a)
+		smack_log(sbj_known->smk_known, obj_known->smk_known,
+			  mode, rc, a);
+#endif
+	return rc;
+}
+
+/**
+ * smk_curacc - determine if current has a specific access to an object
+ * @obj_known: a pointer to the object's Smack label entry
+ * @mode: the access requested, in "MAY" format
+ * @a : common audit data
+ *
+ * This function checks the current subject label/object label pair
+ * in the access rule list and returns 0 if the access is permitted,
+ * non zero otherwise. It allows that current may have the capability
+ * to override the rules.
+ */
+int smk_curacc(struct smack_known *obj_known,
+	       u32 mode, struct smk_audit_info *a)
+{
+	struct task_smack *tsp = smack_cred(current_cred());
+
+	return smk_tskacc(tsp, obj_known, mode, a);
+}
+
+#ifdef CONFIG_AUDIT
+/**
+ * smack_str_from_perm : helper to transalate an int to a
+ * readable string
+ * @string : the string to fill
+ * @access : the int
+ *
+ */
+static inline void smack_str_from_perm(char *string, int access)
+{
+	int i = 0;
+
+	if (access & MAY_READ)
+		string[i++] = 'r';
+	if (access & MAY_WRITE)
+		string[i++] = 'w';
+	if (access & MAY_EXEC)
+		string[i++] = 'x';
+	if (access & MAY_APPEND)
+		string[i++] = 'a';
+	if (access & MAY_TRANSMUTE)
+		string[i++] = 't';
+	if (access & MAY_LOCK)
+		string[i++] = 'l';
+	string[i] = '\0';
+}
+/**
+ * smack_log_callback - SMACK specific information
+ * will be called by generic audit code
+ * @ab : the audit_buffer
+ * @a  : audit_data
+ *
+ */
+static void smack_log_callback(struct audit_buffer *ab, void *a)
+{
+	struct common_audit_data *ad = a;
+	struct smack_audit_data *sad = ad->smack_audit_data;
+	audit_log_format(ab, "lsm=SMACK fn=%s action=%s",
+			 ad->smack_audit_data->function,
+			 sad->result ? "denied" : "granted");
+	audit_log_format(ab, " subject=");
+	audit_log_untrustedstring(ab, sad->subject);
+	audit_log_format(ab, " object=");
+	audit_log_untrustedstring(ab, sad->object);
+	if (sad->request[0] == '\0')
+		audit_log_format(ab, " labels_differ");
+	else
+		audit_log_format(ab, " requested=%s", sad->request);
+}
+
+/**
+ *  smack_log - Audit the granting or denial of permissions.
+ *  @subject_label : smack label of the requester
+ *  @object_label  : smack label of the object being accessed
+ *  @request: requested permissions
+ *  @result: result from smk_access
+ *  @ad:  auxiliary audit data
+ *
+ * Audit the granting or denial of permissions in accordance
+ * with the policy.
+ */
+void smack_log(char *subject_label, char *object_label, int request,
+	       int result, struct smk_audit_info *ad)
+{
+#ifdef CONFIG_SECURITY_SMACK_BRINGUP
+	char request_buffer[SMK_NUM_ACCESS_TYPE + 5];
+#else
+	char request_buffer[SMK_NUM_ACCESS_TYPE + 1];
+#endif
+	struct smack_audit_data *sad;
+	struct common_audit_data *a = &ad->a;
+
+	/* check if we have to log the current event */
+	if (result < 0 && (log_policy & SMACK_AUDIT_DENIED) == 0)
+		return;
+	if (result == 0 && (log_policy & SMACK_AUDIT_ACCEPT) == 0)
+		return;
+
+	sad = a->smack_audit_data;
+
+	if (sad->function == NULL)
+		sad->function = "unknown";
+
+	/* end preparing the audit data */
+	smack_str_from_perm(request_buffer, request);
+	sad->subject = subject_label;
+	sad->object  = object_label;
+#ifdef CONFIG_SECURITY_SMACK_BRINGUP
+	/*
+	 * The result may be positive in bringup mode.
+	 * A positive result is an allow, but not for normal reasons.
+	 * Mark it as successful, but don't filter it out even if
+	 * the logging policy says to do so.
+	 */
+	if (result == SMACK_UNCONFINED_SUBJECT)
+		strcat(request_buffer, "(US)");
+	else if (result == SMACK_UNCONFINED_OBJECT)
+		strcat(request_buffer, "(UO)");
+
+	if (result > 0)
+		result = 0;
+#endif
+	sad->request = request_buffer;
+	sad->result  = result;
+
+	common_lsm_audit(a, smack_log_callback, NULL);
+}
+#else /* #ifdef CONFIG_AUDIT */
+void smack_log(char *subject_label, char *object_label, int request,
+               int result, struct smk_audit_info *ad)
+{
+}
+#endif
+
+DEFINE_MUTEX(smack_known_lock);
+
+struct hlist_head smack_known_hash[SMACK_HASH_SLOTS];
+
+/**
+ * smk_insert_entry - insert a smack label into a hash map,
+ * @skp: smack label
+ *
+ * this function must be called under smack_known_lock
+ */
+void smk_insert_entry(struct smack_known *skp)
+{
+	unsigned int hash;
+	struct hlist_head *head;
+
+	hash = full_name_hash(NULL, skp->smk_known, strlen(skp->smk_known));
+	head = &smack_known_hash[hash & (SMACK_HASH_SLOTS - 1)];
+
+	hlist_add_head_rcu(&skp->smk_hashed, head);
+	list_add_rcu(&skp->list, &smack_known_list);
+}
+
+/**
+ * smk_find_entry - find a label on the list, return the list entry
+ * @string: a text string that might be a Smack label
+ *
+ * Returns a pointer to the entry in the label list that
+ * matches the passed string or NULL if not found.
+ */
+struct smack_known *smk_find_entry(const char *string)
+{
+	unsigned int hash;
+	struct hlist_head *head;
+	struct smack_known *skp;
+
+	hash = full_name_hash(NULL, string, strlen(string));
+	head = &smack_known_hash[hash & (SMACK_HASH_SLOTS - 1)];
+
+	hlist_for_each_entry_rcu(skp, head, smk_hashed)
+		if (strcmp(skp->smk_known, string) == 0)
+			return skp;
+
+	return NULL;
+}
+
+/**
+ * smk_parse_smack - parse smack label from a text string
+ * @string: a text string that might contain a Smack label
+ * @len: the maximum size, or zero if it is NULL terminated.
+ *
+ * Returns a pointer to the clean label or an error code.
+ */
+char *smk_parse_smack(const char *string, int len)
+{
+	char *smack;
+	int i;
+
+	if (len <= 0)
+		len = strlen(string) + 1;
+
+	/*
+	 * Reserve a leading '-' as an indicator that
+	 * this isn't a label, but an option to interfaces
+	 * including /smack/cipso and /smack/cipso2
+	 */
+	if (string[0] == '-')
+		return ERR_PTR(-EINVAL);
+
+	for (i = 0; i < len; i++)
+		if (string[i] > '~' || string[i] <= ' ' || string[i] == '/' ||
+		    string[i] == '"' || string[i] == '\\' || string[i] == '\'')
+			break;
+
+	if (i == 0 || i >= SMK_LONGLABEL)
+		return ERR_PTR(-EINVAL);
+
+	smack = kstrndup(string, i, GFP_NOFS);
+	if (!smack)
+		return ERR_PTR(-ENOMEM);
+	return smack;
+}
+
+/**
+ * smk_netlbl_mls - convert a catset to netlabel mls categories
+ * @level: MLS sensitivity level
+ * @catset: the Smack categories
+ * @sap: where to put the netlabel categories
+ * @len: number of bytes for the levels in a CIPSO IP option
+ *
+ * Allocates and fills attr.mls
+ * Returns 0 on success, error code on failure.
+ */
+int smk_netlbl_mls(int level, char *catset, struct netlbl_lsm_secattr *sap,
+			int len)
+{
+	unsigned char *cp;
+	unsigned char m;
+	int cat;
+	int rc;
+	int byte;
+
+	sap->flags |= NETLBL_SECATTR_MLS_CAT;
+	sap->attr.mls.lvl = level;
+	sap->attr.mls.cat = NULL;
+
+	for (cat = 1, cp = catset, byte = 0; byte < len; cp++, byte++)
+		for (m = 0x80; m != 0; m >>= 1, cat++) {
+			if ((m & *cp) == 0)
+				continue;
+			rc = netlbl_catmap_setbit(&sap->attr.mls.cat,
+						  cat, GFP_NOFS);
+			if (rc < 0) {
+				netlbl_catmap_free(sap->attr.mls.cat);
+				return rc;
+			}
+		}
+
+	return 0;
+}
+
+/**
+ * smack_populate_secattr - fill in the smack_known netlabel information
+ * @skp: pointer to the structure to fill
+ *
+ * Populate the netlabel secattr structure for a Smack label.
+ *
+ * Returns 0 unless creating the category mapping fails
+ */
+int smack_populate_secattr(struct smack_known *skp)
+{
+	int slen;
+
+	skp->smk_netlabel.attr.secid = skp->smk_secid;
+	skp->smk_netlabel.domain = skp->smk_known;
+	skp->smk_netlabel.cache = netlbl_secattr_cache_alloc(GFP_ATOMIC);
+	if (skp->smk_netlabel.cache != NULL) {
+		skp->smk_netlabel.flags |= NETLBL_SECATTR_CACHE;
+		skp->smk_netlabel.cache->free = NULL;
+		skp->smk_netlabel.cache->data = skp;
+	}
+	skp->smk_netlabel.flags |= NETLBL_SECATTR_SECID |
+				   NETLBL_SECATTR_MLS_LVL |
+				   NETLBL_SECATTR_DOMAIN;
+	/*
+	 * If direct labeling works use it.
+	 * Otherwise use mapped labeling.
+	 */
+	slen = strlen(skp->smk_known);
+	if (slen < SMK_CIPSOLEN)
+		return smk_netlbl_mls(smack_cipso_direct, skp->smk_known,
+				      &skp->smk_netlabel, slen);
+
+	return smk_netlbl_mls(smack_cipso_mapped, (char *)&skp->smk_secid,
+			      &skp->smk_netlabel, sizeof(skp->smk_secid));
+}
+
+/**
+ * smk_import_entry - import a label, return the list entry
+ * @string: a text string that might be a Smack label
+ * @len: the maximum size, or zero if it is NULL terminated.
+ *
+ * Returns a pointer to the entry in the label list that
+ * matches the passed string, adding it if necessary,
+ * or an error code.
+ */
+struct smack_known *smk_import_entry(const char *string, int len)
+{
+	struct smack_known *skp;
+	char *smack;
+	int rc;
+
+	smack = smk_parse_smack(string, len);
+	if (IS_ERR(smack))
+		return ERR_CAST(smack);
+
+	mutex_lock(&smack_known_lock);
+
+	skp = smk_find_entry(smack);
+	if (skp != NULL)
+		goto freeout;
+
+	skp = kzalloc(sizeof(*skp), GFP_NOFS);
+	if (skp == NULL) {
+		skp = ERR_PTR(-ENOMEM);
+		goto freeout;
+	}
+
+	skp->smk_known = smack;
+	skp->smk_secid = smack_next_secid++;
+
+	rc = smack_populate_secattr(skp);
+	if (rc >= 0) {
+		INIT_LIST_HEAD(&skp->smk_rules);
+		mutex_init(&skp->smk_rules_lock);
+		/*
+		 * Make sure that the entry is actually
+		 * filled before putting it on the list.
+		 */
+		smk_insert_entry(skp);
+		goto unlockout;
+	}
+	kfree(skp);
+	skp = ERR_PTR(rc);
+freeout:
+	kfree(smack);
+unlockout:
+	mutex_unlock(&smack_known_lock);
+
+	return skp;
+}
+
+/**
+ * smack_from_secid - find the Smack label associated with a secid
+ * @secid: an integer that might be associated with a Smack label
+ *
+ * Returns a pointer to the appropriate Smack label entry if there is one,
+ * otherwise a pointer to the invalid Smack label.
+ */
+struct smack_known *smack_from_secid(const u32 secid)
+{
+	struct smack_known *skp;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(skp, &smack_known_list, list) {
+		if (skp->smk_secid == secid) {
+			rcu_read_unlock();
+			return skp;
+		}
+	}
+
+	/*
+	 * If we got this far someone asked for the translation
+	 * of a secid that is not on the list.
+	 */
+	rcu_read_unlock();
+	return &smack_known_huh;
+}
+
+/*
+ * Unless a process is running with one of these labels
+ * even having CAP_MAC_OVERRIDE isn't enough to grant
+ * privilege to violate MAC policy. If no labels are
+ * designated (the empty list case) capabilities apply to
+ * everyone.
+ */
+LIST_HEAD(smack_onlycap_list);
+DEFINE_MUTEX(smack_onlycap_lock);
+
+/**
+ * smack_privileged_cred - are all privilege requirements met by cred
+ * @cap: The requested capability
+ * @cred: the credential to use
+ *
+ * Is the task privileged and allowed to be privileged
+ * by the onlycap rule.
+ *
+ * Returns true if the task is allowed to be privileged, false if it's not.
+ */
+bool smack_privileged_cred(int cap, const struct cred *cred)
+{
+	struct task_smack *tsp = smack_cred(cred);
+	struct smack_known *skp = tsp->smk_task;
+	struct smack_known_list_elem *sklep;
+	int rc;
+
+	rc = cap_capable(cred, &init_user_ns, cap, CAP_OPT_NONE);
+	if (rc)
+		return false;
+
+	rcu_read_lock();
+	if (list_empty(&smack_onlycap_list)) {
+		rcu_read_unlock();
+		return true;
+	}
+
+	list_for_each_entry_rcu(sklep, &smack_onlycap_list, list) {
+		if (sklep->smk_label == skp) {
+			rcu_read_unlock();
+			return true;
+		}
+	}
+	rcu_read_unlock();
+
+	return false;
+}
+
+/**
+ * smack_privileged - are all privilege requirements met
+ * @cap: The requested capability
+ *
+ * Is the task privileged and allowed to be privileged
+ * by the onlycap rule.
+ *
+ * Returns true if the task is allowed to be privileged, false if it's not.
+ */
+bool smack_privileged(int cap)
+{
+	/*
+	 * All kernel tasks are privileged
+	 */
+	if (unlikely(current->flags & PF_KTHREAD))
+		return true;
+
+	return smack_privileged_cred(cap, current_cred());
+}