diff options
Diffstat (limited to 'security/smack/smack_access.c')
| -rw-r--r-- | security/smack/smack_access.c | 134 |
1 files changed, 72 insertions, 62 deletions
diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c index 9637e107f7ea..cc7cb6edba08 100644 --- a/security/smack/smack_access.c +++ b/security/smack/smack_access.c @@ -77,14 +77,19 @@ int log_policy = SMACK_AUDIT_DENIED; * entry is found returns -ENOENT. * * NOTE: - * Even though Smack labels are usually shared on smack_list - * labels that come in off the network can't be imported - * and added to the list for locking reasons. * - * Therefore, it is necessary to check the contents of the labels, - * not just the pointer values. Of course, in most cases the labels - * will be on the list, so checking the pointers may be a worthwhile - * optimization. + * 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. */ int smk_access_entry(char *subject_label, char *object_label, struct list_head *rule_list) @@ -93,13 +98,10 @@ int smk_access_entry(char *subject_label, char *object_label, struct smack_rule *srp; list_for_each_entry_rcu(srp, rule_list, list) { - if (srp->smk_subject == subject_label || - strcmp(srp->smk_subject, subject_label) == 0) { - if (srp->smk_object == object_label || - strcmp(srp->smk_object, object_label) == 0) { - may = srp->smk_access; - break; - } + if (srp->smk_object == object_label && + srp->smk_subject == subject_label) { + may = srp->smk_access; + break; } } @@ -117,18 +119,12 @@ int smk_access_entry(char *subject_label, char *object_label, * access rule list and returns 0 if the access is permitted, * non zero otherwise. * - * Even though Smack labels are usually shared on smack_list - * labels that come in off the network can't be imported - * and added to the list for locking reasons. - * - * Therefore, it is necessary to check the contents of the labels, - * not just the pointer values. Of course, in most cases the labels - * will be on the list, so checking the pointers may be a worthwhile - * optimization. + * Smack labels are shared on smack_list */ int smk_access(char *subject_label, char *object_label, int request, struct smk_audit_info *a) { + struct smack_known *skp; int may = MAY_NOT; int rc = 0; @@ -137,8 +133,7 @@ int smk_access(char *subject_label, char *object_label, int request, * * A star subject can't access any object. */ - if (subject_label == smack_known_star.smk_known || - strcmp(subject_label, smack_known_star.smk_known) == 0) { + if (subject_label == smack_known_star.smk_known) { rc = -EACCES; goto out_audit; } @@ -148,33 +143,27 @@ int smk_access(char *subject_label, char *object_label, int request, * An internet subject can access any object. */ if (object_label == smack_known_web.smk_known || - subject_label == smack_known_web.smk_known || - strcmp(object_label, smack_known_web.smk_known) == 0 || - strcmp(subject_label, smack_known_web.smk_known) == 0) + subject_label == smack_known_web.smk_known) goto out_audit; /* * A star object can be accessed by any subject. */ - if (object_label == smack_known_star.smk_known || - strcmp(object_label, smack_known_star.smk_known) == 0) + if (object_label == smack_known_star.smk_known) goto out_audit; /* * An object can be accessed in any way by a subject * with the same label. */ - if (subject_label == object_label || - strcmp(subject_label, object_label) == 0) + if (subject_label == object_label) goto out_audit; /* * A hat subject can read any object. * A floor object can be read by any subject. */ if ((request & MAY_ANYREAD) == request) { - if (object_label == smack_known_floor.smk_known || - strcmp(object_label, smack_known_floor.smk_known) == 0) + if (object_label == smack_known_floor.smk_known) goto out_audit; - if (subject_label == smack_known_hat.smk_known || - strcmp(subject_label, smack_known_hat.smk_known) == 0) + if (subject_label == smack_known_hat.smk_known) goto out_audit; } /* @@ -184,8 +173,9 @@ int smk_access(char *subject_label, char *object_label, int request, * good. A negative response from smk_access_entry() * indicates there is no entry for this pair. */ + skp = smk_find_entry(subject_label); rcu_read_lock(); - may = smk_access_entry(subject_label, object_label, &smack_rule_list); + may = smk_access_entry(subject_label, object_label, &skp->smk_rules); rcu_read_unlock(); if (may > 0 && (request & may) == request) @@ -344,17 +334,32 @@ void smack_log(char *subject_label, char *object_label, int request, static DEFINE_MUTEX(smack_known_lock); /** - * smk_import_entry - import a label, return the list entry + * smk_find_entry - find a label on the list, 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. + * matches the passed string. */ -struct smack_known *smk_import_entry(const char *string, int len) +struct smack_known *smk_find_entry(const char *string) { struct smack_known *skp; - char smack[SMK_LABELLEN]; + + list_for_each_entry_rcu(skp, &smack_known_list, list) { + if (strncmp(skp->smk_known, string, SMK_MAXLEN) == 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. + * @smack: parsed smack label, or NULL if parse error + */ +void smk_parse_smack(const char *string, int len, char *smack) +{ int found; int i; @@ -372,27 +377,38 @@ struct smack_known *smk_import_entry(const char *string, int len) } else smack[i] = string[i]; } +} + +/** + * 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. + */ +struct smack_known *smk_import_entry(const char *string, int len) +{ + struct smack_known *skp; + char smack[SMK_LABELLEN]; + smk_parse_smack(string, len, smack); if (smack[0] == '\0') return NULL; mutex_lock(&smack_known_lock); - found = 0; - list_for_each_entry_rcu(skp, &smack_known_list, list) { - if (strncmp(skp->smk_known, smack, SMK_MAXLEN) == 0) { - found = 1; - break; - } - } + skp = smk_find_entry(smack); - if (found == 0) { + if (skp == NULL) { skp = kzalloc(sizeof(struct smack_known), GFP_KERNEL); if (skp != NULL) { strncpy(skp->smk_known, smack, SMK_MAXLEN); skp->smk_secid = smack_next_secid++; skp->smk_cipso = NULL; + INIT_LIST_HEAD(&skp->smk_rules); spin_lock_init(&skp->smk_cipsolock); + mutex_init(&skp->smk_rules_lock); /* * Make sure that the entry is actually * filled before putting it on the list. @@ -480,19 +496,12 @@ u32 smack_to_secid(const char *smack) * smack_from_cipso - find the Smack label associated with a CIPSO option * @level: Bell & LaPadula level from the network * @cp: Bell & LaPadula categories from the network - * @result: where to put the Smack value * * This is a simple lookup in the label table. * - * This is an odd duck as far as smack handling goes in that - * it sends back a copy of the smack label rather than a pointer - * to the master list. This is done because it is possible for - * a foreign host to send a smack label that is new to this - * machine and hence not on the list. That would not be an - * issue except that adding an entry to the master list can't - * be done at that point. + * Return the matching label from the label list or NULL. */ -void smack_from_cipso(u32 level, char *cp, char *result) +char *smack_from_cipso(u32 level, char *cp) { struct smack_known *kp; char *final = NULL; @@ -509,12 +518,13 @@ void smack_from_cipso(u32 level, char *cp, char *result) final = kp->smk_known; spin_unlock_bh(&kp->smk_cipsolock); + + if (final != NULL) + break; } rcu_read_unlock(); - if (final == NULL) - final = smack_known_huh.smk_known; - strncpy(result, final, SMK_MAXLEN); - return; + + return final; } /** |