diff options
Diffstat (limited to 'security/smack/smack_access.c')
| -rw-r--r-- | security/smack/smack_access.c | 474 |
1 files changed, 337 insertions, 137 deletions
diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c index 6a0377f38620..fc507dcc7ea5 100644 --- a/security/smack/smack_access.c +++ b/security/smack/smack_access.c @@ -1,13 +1,9 @@ +// SPDX-License-Identifier: GPL-2.0-only /* * Copyright (C) 2007 Casey Schaufler <casey@schaufler-ca.com> * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation, version 2. - * * Author: * Casey Schaufler <casey@schaufler-ca.com> - * */ #include <linux/types.h> @@ -36,11 +32,6 @@ struct smack_known smack_known_floor = { .smk_secid = 5, }; -struct smack_known smack_known_invalid = { - .smk_known = "", - .smk_secid = 6, -}; - struct smack_known smack_known_web = { .smk_known = "@", .smk_secid = 7, @@ -54,11 +45,13 @@ LIST_HEAD(smack_known_list); */ static u32 smack_next_secid = 10; +#ifdef CONFIG_AUDIT /* * what events do we log * can be overwritten at run-time by /smack/logging */ int log_policy = SMACK_AUDIT_DENIED; +#endif /* CONFIG_AUDIT */ /** * smk_access_entry - look up matching access rule @@ -84,28 +77,34 @@ int log_policy = SMACK_AUDIT_DENIED; * * 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 && + if (srp->smk_object->smk_known == object_label && srp->smk_subject->smk_known == subject_label) { - may = srp->smk_access; - break; + int may = srp->smk_access; + /* + * MAY_WRITE implies MAY_LOCK. + */ + if ((may & MAY_WRITE) == MAY_WRITE) + may |= MAY_LOCK; + return may; } } - return may; + return -ENOENT; } /** * 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 + * @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 * @@ -115,18 +114,19 @@ int smk_access_entry(char *subject_label, char *object_label, * * Smack labels are shared on smack_list */ -int smk_access(struct smack_known *subject_known, char *object_label, - int request, struct smk_audit_info *a) +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_known == &smack_known_star) { + if (subject == &smack_known_star) { rc = -EACCES; goto out_audit; } @@ -135,28 +135,28 @@ int smk_access(struct smack_known *subject_known, char *object_label, * Tasks cannot be assigned the internet label. * An internet subject can access any object. */ - if (object_label == smack_known_web.smk_known || - subject_known == &smack_known_web) + if (object == &smack_known_web || subject == &smack_known_web) goto out_audit; /* * A star object can be accessed by any subject. */ - if (object_label == smack_known_star.smk_known) + 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_known->smk_known == object_label) + if (subject->smk_known == object->smk_known) goto out_audit; /* - * A hat subject can read any object. - * A floor object can be read by any subject. + * 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) { - if (object_label == smack_known_floor.smk_known) + if ((request & MAY_ANYREAD) == request || + (request & MAY_LOCK) == request) { + if (object == &smack_known_floor) goto out_audit; - if (subject_known == &smack_known_hat) + if (subject == &smack_known_hat) goto out_audit; } /* @@ -167,52 +167,75 @@ int smk_access(struct smack_known *subject_known, char *object_label, * indicates there is no entry for this pair. */ rcu_read_lock(); - may = smk_access_entry(subject_known->smk_known, object_label, - &subject_known->smk_rules); + may = smk_access_entry(subject->smk_known, object->smk_known, + &subject->smk_rules); rcu_read_unlock(); - if (may > 0 && (request & may) == request) + 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 - rc = -EACCES; 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_known->smk_known, object_label, request, - rc, a); + smack_log(subject->smk_known, object->smk_known, + request, 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 + * 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 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 *tsp, struct smack_known *obj_known, + u32 mode, struct smk_audit_info *a) { - struct task_smack *tsp = current_security(); - struct smack_known *skp = smk_of_task(tsp); + struct smack_known *sbj_known = smk_of_task(tsp); int may; int rc; /* * Check the global rule list */ - rc = smk_access(skp, obj_label, mode, NULL); - if (rc == 0) { + 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(skp->smk_known, obj_label, - &tsp->smk_rules); + 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) @@ -221,7 +244,7 @@ int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a) } /* - * Allow for priviliged to override policy. + * Allow for privileged to override policy. */ if (rc != 0 && smack_privileged(CAP_MAC_OVERRIDE)) rc = 0; @@ -229,22 +252,42 @@ int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a) out_audit: #ifdef CONFIG_AUDIT if (a) - smack_log(skp->smk_known, obj_label, mode, rc, a); + smack_log(sbj_known->smk_known, obj_known->smk_known, + mode, rc, a); #endif return rc; } -#ifdef CONFIG_AUDIT /** - * smack_str_from_perm : helper to transalate an int to a + * 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); +} + +/** + * smack_str_from_perm : helper to translate 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 smack_str_from_perm(char *string, int access) { int i = 0; + if (access & MAY_READ) string[i++] = 'r'; if (access & MAY_WRITE) @@ -255,8 +298,17 @@ static inline void smack_str_from_perm(char *string, int access) string[i++] = 'a'; if (access & MAY_TRANSMUTE) string[i++] = 't'; + if (access & MAY_LOCK) + string[i++] = 'l'; + if (access & MAY_BRINGUP) + string[i++] = 'b'; + if (i == 0) + string[i++] = '-'; string[i] = '\0'; + return i; } + +#ifdef CONFIG_AUDIT /** * smack_log_callback - SMACK specific information * will be called by generic audit code @@ -275,7 +327,10 @@ static void smack_log_callback(struct audit_buffer *ab, void *a) 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); } /** @@ -284,7 +339,7 @@ static void smack_log_callback(struct audit_buffer *ab, void *a) * @object_label : smack label of the object being accessed * @request: requested permissions * @result: result from smk_access - * @a: auxiliary audit data + * @ad: auxiliary audit data * * Audit the granting or denial of permissions in accordance * with the policy. @@ -292,12 +347,16 @@ static void smack_log_callback(struct audit_buffer *ab, void *a) 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) + if (result < 0 && (log_policy & SMACK_AUDIT_DENIED) == 0) return; if (result == 0 && (log_policy & SMACK_AUDIT_ACCEPT) == 0) return; @@ -311,6 +370,21 @@ void smack_log(char *subject_label, char *object_label, int request, 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; @@ -325,39 +399,63 @@ void smack_log(char *subject_label, char *object_label, int request, 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. + * 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; - list_for_each_entry_rcu(skp, &smack_known_list, list) { + 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. + * smk_parse_label_len - calculate the length of the starting segment + * in the string that constitutes a valid smack label + * @string: a text string that might contain a Smack label at the beginning + * @len: the maximum size to look into, may be zero if string is null-terminated * - * Returns a pointer to the clean label, or NULL + * Returns the length of the segment (0 < L < SMK_LONGLABEL) or an error code. */ -char *smk_parse_smack(const char *string, int len) +int smk_parse_label_len(const char *string, int len) { - char *smack; int i; - if (len <= 0) - len = strlen(string) + 1; + if (len <= 0 || len > SMK_LONGLABEL) + len = SMK_LONGLABEL; /* * Reserve a leading '-' as an indicator that @@ -365,7 +463,7 @@ char *smk_parse_smack(const char *string, int len) * including /smack/cipso and /smack/cipso2 */ if (string[0] == '-') - return NULL; + return -EINVAL; for (i = 0; i < len; i++) if (string[i] > '~' || string[i] <= ' ' || string[i] == '/' || @@ -373,20 +471,39 @@ char *smk_parse_smack(const char *string, int len) break; if (i == 0 || i >= SMK_LONGLABEL) - return NULL; + return -EINVAL; - smack = kzalloc(i + 1, GFP_KERNEL); - if (smack != NULL) { - strncpy(smack, string, i + 1); - smack[i] = '\0'; - } + return i; +} + +/** + * smk_parse_smack - copy the starting segment in the string + * that constitutes a valid smack label + * @string: a text string that might contain a Smack label at the beginning + * @len: the maximum size to look into, may be zero if string is null-terminated + * + * Returns a pointer to the copy of the label or an error code. + */ +char *smk_parse_smack(const char *string, int len) +{ + char *smack; + int i = smk_parse_label_len(string, len); + + if (i < 0) + 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. @@ -402,19 +519,16 @@ int smk_netlbl_mls(int level, char *catset, struct netlbl_lsm_secattr *sap, 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; + 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_secattr_catmap_setbit(sap->attr.mls.cat, - cat, GFP_ATOMIC); + rc = netlbl_catmap_setbit(&sap->attr.mls.cat, + cat, GFP_NOFS); if (rc < 0) { - netlbl_secattr_catmap_free(sap->attr.mls.cat); + netlbl_catmap_free(sap->attr.mls.cat); return rc; } } @@ -423,23 +537,54 @@ int smk_netlbl_mls(int level, char *catset, struct netlbl_lsm_secattr *sap, } /** - * 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. + * smack_populate_secattr - fill in the smack_known netlabel information + * @skp: pointer to the structure to fill * - * Returns a pointer to the entry in the label list that - * matches the passed string, adding it if necessary. + * Populate the netlabel secattr structure for a Smack label. + * + * Returns 0 unless creating the category mapping fails */ -struct smack_known *smk_import_entry(const char *string, int len) +int smack_populate_secattr(struct smack_known *skp) { - struct smack_known *skp; - char *smack; int slen; - int rc; - smack = smk_parse_smack(string, len); - if (smack == NULL) - return NULL; + 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_valid_allocated_label - import a label, return the list entry + * @smack: a text string that is a valid Smack label and may be kfree()ed. + * It is consumed: either becomes a part of the entry or kfree'ed. + * @gfp: Allocation type + * + * Returns: see description of smk_import_entry() + */ +static struct smack_known * +smk_import_allocated_label(char *smack, gfp_t gfp) +{ + struct smack_known *skp; + int rc; mutex_lock(&smack_known_lock); @@ -447,27 +592,16 @@ struct smack_known *smk_import_entry(const char *string, int len) if (skp != NULL) goto freeout; - skp = kzalloc(sizeof(*skp), GFP_KERNEL); - if (skp == NULL) + skp = kzalloc(sizeof(*skp), gfp); + if (skp == NULL) { + skp = ERR_PTR(-ENOMEM); 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)); + rc = smack_populate_secattr(skp); if (rc >= 0) { INIT_LIST_HEAD(&skp->smk_rules); mutex_init(&skp->smk_rules_lock); @@ -475,14 +609,11 @@ struct smack_known *smk_import_entry(const char *string, int len) * Make sure that the entry is actually * filled before putting it on the list. */ - list_add_rcu(&skp->list, &smack_known_list); + smk_insert_entry(skp); goto unlockout; } - /* - * smk_netlbl_mls failed. - */ kfree(skp); - skp = NULL; + skp = ERR_PTR(rc); freeout: kfree(smack); unlockout: @@ -492,24 +623,41 @@ unlockout: } /** - * smk_import - import a smack label - * @string: a text string that might be a Smack label - * @len: the maximum size, or zero if it is NULL terminated. + * smk_import_entry - import a label, return the list entry + * @string: a text string that might contain a Smack label at the beginning + * @len: the maximum size to look into, may be zero if string is null-terminated * - * Returns a pointer to the label in the label list that - * matches the passed string, adding it if necessary. + * Returns a pointer to the entry in the label list that + * matches the passed string, adding it if necessary, + * or an error code. */ -char *smk_import(const char *string, int len) +struct smack_known *smk_import_entry(const char *string, int len) { - struct smack_known *skp; + char *smack = smk_parse_smack(string, len); - /* labels cannot begin with a '-' */ - if (string[0] == '-') - return NULL; - skp = smk_import_entry(string, len); - if (skp == NULL) - return NULL; - return skp->smk_known; + if (IS_ERR(smack)) + return ERR_CAST(smack); + + return smk_import_allocated_label(smack, GFP_NOFS); +} + +/** + * smk_import_valid_label - import a label, return the list entry + * @label: a text string that is a valid Smack label, not null-terminated + * @label_len: the length of the text string in the @label + * @gfp: the GFP mask used for allocating memory for the @label text string copy + * + * Return: see description of smk_import_entry() + */ +struct smack_known * +smk_import_valid_label(const char *label, int label_len, gfp_t gfp) +{ + char *smack = kstrndup(label, label_len, gfp); + + if (!smack) + return ERR_PTR(-ENOMEM); + + return smk_import_allocated_label(smack, gfp); } /** @@ -536,21 +684,73 @@ struct smack_known *smack_from_secid(const u32 secid) * of a secid that is not on the list. */ rcu_read_unlock(); - return &smack_known_invalid; + 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_to_secid - find the secid associated with a Smack label - * @smack: the Smack label + * 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 the appropriate secid if there is one, - * otherwise 0 + * Returns true if the task is allowed to be privileged, false if it's not. */ -u32 smack_to_secid(const char *smack) +bool smack_privileged(int cap) { - struct smack_known *skp = smk_find_entry(smack); + /* + * All kernel tasks are privileged + */ + if (unlikely(current->flags & PF_KTHREAD)) + return true; - if (skp == NULL) - return 0; - return skp->smk_secid; + return smack_privileged_cred(cap, current_cred()); } |