diff options
Diffstat (limited to 'security/smack/smack_access.c')
| -rw-r--r-- | security/smack/smack_access.c | 504 |
1 files changed, 306 insertions, 198 deletions
diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c index f4fac64c4da..c062e9467b6 100644 --- a/security/smack/smack_access.c +++ b/security/smack/smack_access.c @@ -19,37 +19,31 @@ struct smack_known smack_known_huh = { .smk_known = "?", .smk_secid = 2, - .smk_cipso = NULL, }; struct smack_known smack_known_hat = { .smk_known = "^", .smk_secid = 3, - .smk_cipso = NULL, }; struct smack_known smack_known_star = { .smk_known = "*", .smk_secid = 4, - .smk_cipso = NULL, }; struct smack_known smack_known_floor = { .smk_known = "_", .smk_secid = 5, - .smk_cipso = NULL, }; struct smack_known smack_known_invalid = { .smk_known = "", .smk_secid = 6, - .smk_cipso = NULL, }; struct smack_known smack_known_web = { .smk_known = "@", .smk_secid = 7, - .smk_cipso = NULL, }; LIST_HEAD(smack_known_list); @@ -67,9 +61,58 @@ static u32 smack_next_secid = 10; int log_policy = SMACK_AUDIT_DENIED; /** - * smk_access - determine if a subject has a specific access to an object + * 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) +{ + int may = -ENOENT; + struct smack_rule *srp; + + list_for_each_entry_rcu(srp, rule_list, list) { + if (srp->smk_object == object_label && + srp->smk_subject->smk_known == subject_label) { + may = srp->smk_access; + break; + } + } + + /* + * MAY_WRITE implies MAY_LOCK. + */ + if ((may & MAY_WRITE) == MAY_WRITE) + may |= MAY_LOCK; + return may; +} + +/** + * smk_access - determine if a subject has a specific access to an object + * @subject_known: a pointer to the subject's Smack label entry + * @object_label: a pointer to the object's Smack label * @request: the access requested, in "MAY" format * @a : a pointer to the audit data * @@ -77,20 +120,12 @@ int log_policy = SMACK_AUDIT_DENIED; * 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) +int smk_access(struct smack_known *subject_known, char *object_label, + int request, struct smk_audit_info *a) { - u32 may = MAY_NOT; - struct smack_rule *srp; + int may = MAY_NOT; int rc = 0; /* @@ -98,8 +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_known == &smack_known_star) { rc = -EACCES; goto out_audit; } @@ -109,107 +143,123 @@ 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_known == &smack_known_web) 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_known->smk_known == 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_known == &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. + * good. A negative response from smk_access_entry() + * indicates there is no entry for this pair. */ rcu_read_lock(); - list_for_each_entry_rcu(srp, &smack_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; - } - } - } + may = smk_access_entry(subject_known->smk_known, object_label, + &subject_known->smk_rules); rcu_read_unlock(); - /* - * This is a bit map operation. - */ - if ((request & may) == request) + + if (may > 0 && (request & may) == request) goto out_audit; rc = -EACCES; out_audit: #ifdef CONFIG_AUDIT if (a) - smack_log(subject_label, object_label, request, rc, a); + smack_log(subject_known->smk_known, object_label, request, + rc, a); #endif return rc; } /** - * smk_curacc - determine if current has a specific access to an object + * smk_tskacc - determine if a task has a specific access to an object + * @tsp: a pointer to the subject task * @obj_label: a pointer to the object's Smack label * @mode: the access requested, in "MAY" format * @a : common audit data * - * This function checks the current subject label/object label pair + * 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 current may have the capability + * non zero otherwise. It allows that the task may have the capability * to override the rules. */ -int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a) +int smk_tskacc(struct task_smack *subject, char *obj_label, + u32 mode, struct smk_audit_info *a) { + struct smack_known *skp = smk_of_task(subject); + int may; int rc; - char *sp = current_security(); - - rc = smk_access(sp, obj_label, mode, NULL); - if (rc == 0) - goto out_audit; /* - * Return if a specific label has been designated as the - * only one that gets privilege and current does not - * have that label. + * Check the global rule list */ - if (smack_onlycap != NULL && smack_onlycap != current->cred->security) - goto out_audit; + rc = smk_access(skp, obj_label, 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(skp->smk_known, obj_label, + &subject->smk_rules); + if (may < 0) + goto out_audit; + if ((mode & may) == mode) + goto out_audit; + rc = -EACCES; + } - if (capable(CAP_MAC_OVERRIDE)) - return 0; + /* + * 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(sp, obj_label, mode, rc, a); + smack_log(skp->smk_known, obj_label, mode, rc, a); #endif return rc; } +/** + * smk_curacc - determine if current has a specific access to an object + * @obj_label: a pointer to the object's Smack label + * @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(char *obj_label, u32 mode, struct smk_audit_info *a) +{ + struct task_smack *tsp = current_security(); + + return smk_tskacc(tsp, obj_label, mode, a); +} + #ifdef CONFIG_AUDIT /** * smack_str_from_perm : helper to transalate an int to a @@ -221,6 +271,7 @@ out_audit: 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) @@ -229,6 +280,10 @@ static inline void smack_str_from_perm(char *string, int access) 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'; } /** @@ -241,15 +296,18 @@ static inline void smack_str_from_perm(char *string, int access) 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; + struct smack_audit_data *sad = ad->smack_audit_data; audit_log_format(ab, "lsm=SMACK fn=%s action=%s", - ad->smack_audit_data.function, + 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); - audit_log_format(ab, " requested=%s", sad->request); + if (sad->request[0] == '\0') + audit_log_format(ab, " labels_differ"); + else + audit_log_format(ab, " requested=%s", sad->request); } /** @@ -276,19 +334,19 @@ void smack_log(char *subject_label, char *object_label, int request, if (result == 0 && (log_policy & SMACK_AUDIT_ACCEPT) == 0) return; - if (a->smack_audit_data.function == NULL) - a->smack_audit_data.function = "unknown"; + sad = a->smack_audit_data; + + if (sad->function == NULL) + sad->function = "unknown"; /* end preparing the audit data */ - sad = &a->smack_audit_data; smack_str_from_perm(request_buffer, request); sad->subject = subject_label; sad->object = object_label; sad->request = request_buffer; sad->result = result; - a->lsm_pre_audit = smack_log_callback; - common_lsm_audit(a); + common_lsm_audit(a, smack_log_callback, NULL); } #else /* #ifdef CONFIG_AUDIT */ void smack_log(char *subject_label, char *object_label, int request, @@ -297,7 +355,127 @@ void smack_log(char *subject_label, char *object_label, int request, } #endif -static DEFINE_MUTEX(smack_known_lock); +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, + * + * 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(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. + */ +struct smack_known *smk_find_entry(const char *string) +{ + unsigned int hash; + struct hlist_head *head; + struct smack_known *skp; + + hash = full_name_hash(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 NULL + */ +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 NULL; + + 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 NULL; + + smack = kzalloc(i + 1, GFP_KERNEL); + if (smack != NULL) { + strncpy(smack, string, i + 1); + smack[i] = '\0'; + } + return smack; +} + +/** + * smk_netlbl_mls - convert a catset to netlabel mls categories + * @catset: the Smack categories + * @sap: where to put the netlabel categories + * + * 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 = netlbl_secattr_catmap_alloc(GFP_ATOMIC); + if (!sap->attr.mls.cat) + return -ENOMEM; + sap->attr.mls.cat->startbit = 0; + + 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_secattr_catmap_setbit(sap->attr.mls.cat, + cat, GFP_ATOMIC); + if (rc < 0) { + netlbl_secattr_catmap_free(sap->attr.mls.cat); + return rc; + } + } + + return 0; +} /** * smk_import_entry - import a label, return the list entry @@ -310,53 +488,59 @@ static DEFINE_MUTEX(smack_known_lock); struct smack_known *smk_import_entry(const char *string, int len) { struct smack_known *skp; - char smack[SMK_LABELLEN]; - int found; - int i; - - if (len <= 0 || len > SMK_MAXLEN) - len = SMK_MAXLEN; - - for (i = 0, found = 0; i < SMK_LABELLEN; i++) { - if (found) - smack[i] = '\0'; - else if (i >= len || string[i] > '~' || string[i] <= ' ' || - string[i] == '/' || string[i] == '"' || - string[i] == '\\' || string[i] == '\'') { - smack[i] = '\0'; - found = 1; - } else - smack[i] = string[i]; - } + char *smack; + int slen; + int rc; - if (smack[0] == '\0') + smack = smk_parse_smack(string, len); + if (smack == NULL) 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 (skp != NULL) + goto freeout; - if (found == 0) { - 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; - spin_lock_init(&skp->smk_cipsolock); - /* - * Make sure that the entry is actually - * filled before putting it on the list. - */ - list_add_rcu(&skp->list, &smack_known_list); - } - } + skp = kzalloc(sizeof(*skp), GFP_KERNEL); + if (skp == NULL) + goto freeout; + skp->smk_known = smack; + skp->smk_secid = smack_next_secid++; + skp->smk_netlabel.domain = skp->smk_known; + skp->smk_netlabel.flags = + NETLBL_SECATTR_DOMAIN | NETLBL_SECATTR_MLS_LVL; + /* + * If direct labeling works use it. + * Otherwise use mapped labeling. + */ + slen = strlen(smack); + if (slen < SMK_CIPSOLEN) + rc = smk_netlbl_mls(smack_cipso_direct, skp->smk_known, + &skp->smk_netlabel, slen); + else + rc = smk_netlbl_mls(smack_cipso_mapped, (char *)&skp->smk_secid, + &skp->smk_netlabel, sizeof(skp->smk_secid)); + + 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; + } + /* + * smk_netlbl_mls failed. + */ + kfree(skp); + skp = NULL; +freeout: + kfree(smack); +unlockout: mutex_unlock(&smack_known_lock); return skp; @@ -387,10 +571,10 @@ char *smk_import(const char *string, int len) * 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 appropraite Smack label if there is one, + * Returns a pointer to the appropriate Smack label entry if there is one, * otherwise a pointer to the invalid Smack label. */ -char *smack_from_secid(const u32 secid) +struct smack_known *smack_from_secid(const u32 secid) { struct smack_known *skp; @@ -398,7 +582,7 @@ char *smack_from_secid(const u32 secid) list_for_each_entry_rcu(skp, &smack_known_list, list) { if (skp->smk_secid == secid) { rcu_read_unlock(); - return skp->smk_known; + return skp; } } @@ -407,7 +591,7 @@ char *smack_from_secid(const u32 secid) * of a secid that is not on the list. */ rcu_read_unlock(); - return smack_known_invalid.smk_known; + return &smack_known_invalid; } /** @@ -419,85 +603,9 @@ char *smack_from_secid(const u32 secid) */ u32 smack_to_secid(const char *smack) { - struct smack_known *skp; - - rcu_read_lock(); - list_for_each_entry_rcu(skp, &smack_known_list, list) { - if (strncmp(skp->smk_known, smack, SMK_MAXLEN) == 0) { - rcu_read_unlock(); - return skp->smk_secid; - } - } - rcu_read_unlock(); - return 0; -} - -/** - * 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. - */ -void smack_from_cipso(u32 level, char *cp, char *result) -{ - struct smack_known *kp; - char *final = NULL; - - rcu_read_lock(); - list_for_each_entry(kp, &smack_known_list, list) { - if (kp->smk_cipso == NULL) - continue; - - spin_lock_bh(&kp->smk_cipsolock); - - if (kp->smk_cipso->smk_level == level && - memcmp(kp->smk_cipso->smk_catset, cp, SMK_LABELLEN) == 0) - final = kp->smk_known; - - spin_unlock_bh(&kp->smk_cipsolock); - } - rcu_read_unlock(); - if (final == NULL) - final = smack_known_huh.smk_known; - strncpy(result, final, SMK_MAXLEN); - return; -} - -/** - * smack_to_cipso - find the CIPSO option to go with a Smack label - * @smack: a pointer to the smack label in question - * @cp: where to put the result - * - * Returns zero if a value is available, non-zero otherwise. - */ -int smack_to_cipso(const char *smack, struct smack_cipso *cp) -{ - struct smack_known *kp; - int found = 0; + struct smack_known *skp = smk_find_entry(smack); - rcu_read_lock(); - list_for_each_entry_rcu(kp, &smack_known_list, list) { - if (kp->smk_known == smack || - strcmp(kp->smk_known, smack) == 0) { - found = 1; - break; - } - } - rcu_read_unlock(); - - if (found == 0 || kp->smk_cipso == NULL) - return -ENOENT; - - memcpy(cp, kp->smk_cipso, sizeof(struct smack_cipso)); - return 0; + if (skp == NULL) + return 0; + return skp->smk_secid; } |