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![Tomasz Stanislawski](/assets/img/avatar_default.png)
Accepted for the smack-next tree after changing the number of slots from 128 to 16. This patch adds a hash table to quicken searching of a smack label by its name. Basically, the patch improves performance of SMACK initialization. Parsing of rules involves translation from a string to a smack_known (aka label) entity which is done in smk_find_entry(). The current implementation of the function iterates over a global list of smack_known resulting in O(N) complexity for smk_find_entry(). The total complexity of SMACK initialization becomes O(rules * labels). Therefore it scales quadratically with a complexity of a system. Applying the patch reduced the complexity of smk_find_entry() to O(1) as long as number of label is in hundreds. If the number of labels is increased please update SMACK_HASH_SLOTS constant defined in security/smack/smack.h. Introducing the configuration of this constant with Kconfig or cmdline might be a good idea. The size of the hash table was adjusted experimentally. The rule set used by TIZEN contains circa 17K rules for 500 labels. The table above contains results of SMACK initialization using 'time smackctl apply' bash command. The 'Ref' is a kernel without this patch applied. The consecutive values refers to value of SMACK_HASH_SLOTS. Every measurement was repeated three times to reduce noise. | Ref | 1 | 2 | 4 | 8 | 16 | 32 | 64 | 128 | 256 | 512 -------------------------------------------------------------------------------------------- Run1 | 1.156 | 1.096 | 0.883 | 0.764 | 0.692 | 0.667 | 0.649 | 0.633 | 0.634 | 0.629 | 0.620 Run2 | 1.156 | 1.111 | 0.885 | 0.764 | 0.694 | 0.661 | 0.649 | 0.651 | 0.634 | 0.638 | 0.623 Run3 | 1.160 | 1.107 | 0.886 | 0.764 | 0.694 | 0.671 | 0.661 | 0.638 | 0.631 | 0.624 | 0.638 AVG | 1.157 | 1.105 | 0.885 | 0.764 | 0.693 | 0.666 | 0.653 | 0.641 | 0.633 | 0.630 | 0.627 Surprisingly, a single hlist is slightly faster than a double-linked list. The speed-up saturates near 64 slots. Therefore I chose value 128 to provide some margin if more labels were used. It looks that IO becomes a new bottleneck. Signed-off-by: Tomasz Stanislawski <t.stanislaws@samsung.com>
579 lines
14 KiB
C
579 lines
14 KiB
C
/*
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* Copyright (C) 2007 Casey Schaufler <casey@schaufler-ca.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, version 2.
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*
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* Author:
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* Casey Schaufler <casey@schaufler-ca.com>
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*
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*/
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#include <linux/types.h>
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#include <linux/slab.h>
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#include <linux/fs.h>
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#include <linux/sched.h>
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#include "smack.h"
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struct smack_known smack_known_huh = {
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.smk_known = "?",
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.smk_secid = 2,
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};
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struct smack_known smack_known_hat = {
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.smk_known = "^",
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.smk_secid = 3,
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};
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struct smack_known smack_known_star = {
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.smk_known = "*",
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.smk_secid = 4,
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};
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struct smack_known smack_known_floor = {
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.smk_known = "_",
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.smk_secid = 5,
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};
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struct smack_known smack_known_invalid = {
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.smk_known = "",
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.smk_secid = 6,
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};
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struct smack_known smack_known_web = {
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.smk_known = "@",
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.smk_secid = 7,
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};
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LIST_HEAD(smack_known_list);
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/*
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* The initial value needs to be bigger than any of the
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* known values above.
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*/
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static u32 smack_next_secid = 10;
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/*
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* what events do we log
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* can be overwritten at run-time by /smack/logging
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*/
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int log_policy = SMACK_AUDIT_DENIED;
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/**
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* smk_access_entry - look up matching access rule
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* @subject_label: a pointer to the subject's Smack label
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* @object_label: a pointer to the object's Smack label
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* @rule_list: the list of rules to search
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*
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* This function looks up the subject/object pair in the
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* access rule list and returns the access mode. If no
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* entry is found returns -ENOENT.
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*
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* NOTE:
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*
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* Earlier versions of this function allowed for labels that
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* were not on the label list. This was done to allow for
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* labels to come over the network that had never been seen
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* before on this host. Unless the receiving socket has the
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* star label this will always result in a failure check. The
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* star labeled socket case is now handled in the networking
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* hooks so there is no case where the label is not on the
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* label list. Checking to see if the address of two labels
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* is the same is now a reliable test.
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*
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* Do the object check first because that is more
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* likely to differ.
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*/
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int smk_access_entry(char *subject_label, char *object_label,
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struct list_head *rule_list)
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{
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int may = -ENOENT;
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struct smack_rule *srp;
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list_for_each_entry_rcu(srp, rule_list, list) {
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if (srp->smk_object == object_label &&
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srp->smk_subject->smk_known == subject_label) {
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may = srp->smk_access;
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break;
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}
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}
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return may;
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}
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/**
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* smk_access - determine if a subject has a specific access to an object
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* @subject_known: a pointer to the subject's Smack label entry
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* @object_label: a pointer to the object's Smack label
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* @request: the access requested, in "MAY" format
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* @a : a pointer to the audit data
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*
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* This function looks up the subject/object pair in the
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* access rule list and returns 0 if the access is permitted,
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* non zero otherwise.
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*
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* Smack labels are shared on smack_list
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*/
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int smk_access(struct smack_known *subject_known, char *object_label,
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int request, struct smk_audit_info *a)
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{
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int may = MAY_NOT;
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int rc = 0;
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/*
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* Hardcoded comparisons.
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*
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* A star subject can't access any object.
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*/
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if (subject_known == &smack_known_star) {
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rc = -EACCES;
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goto out_audit;
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}
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/*
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* An internet object can be accessed by any subject.
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* Tasks cannot be assigned the internet label.
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* An internet subject can access any object.
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*/
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if (object_label == smack_known_web.smk_known ||
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subject_known == &smack_known_web)
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goto out_audit;
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/*
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* A star object can be accessed by any subject.
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*/
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if (object_label == smack_known_star.smk_known)
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goto out_audit;
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/*
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* An object can be accessed in any way by a subject
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* with the same label.
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*/
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if (subject_known->smk_known == object_label)
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goto out_audit;
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/*
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* A hat subject can read any object.
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* A floor object can be read by any subject.
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*/
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if ((request & MAY_ANYREAD) == request) {
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if (object_label == smack_known_floor.smk_known)
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goto out_audit;
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if (subject_known == &smack_known_hat)
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goto out_audit;
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}
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/*
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* Beyond here an explicit relationship is required.
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* If the requested access is contained in the available
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* access (e.g. read is included in readwrite) it's
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* good. A negative response from smk_access_entry()
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* indicates there is no entry for this pair.
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*/
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rcu_read_lock();
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may = smk_access_entry(subject_known->smk_known, object_label,
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&subject_known->smk_rules);
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rcu_read_unlock();
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if (may > 0 && (request & may) == request)
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goto out_audit;
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rc = -EACCES;
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out_audit:
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#ifdef CONFIG_AUDIT
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if (a)
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smack_log(subject_known->smk_known, object_label, request,
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rc, a);
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#endif
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return rc;
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}
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/**
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* smk_curacc - determine if current has a specific access to an object
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* @obj_label: a pointer to the object's Smack label
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* @mode: the access requested, in "MAY" format
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* @a : common audit data
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*
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* This function checks the current subject label/object label pair
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* in the access rule list and returns 0 if the access is permitted,
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* non zero otherwise. It allows that current may have the capability
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* to override the rules.
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*/
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int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a)
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{
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struct task_smack *tsp = current_security();
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struct smack_known *skp = smk_of_task(tsp);
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int may;
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int rc;
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/*
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* Check the global rule list
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*/
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rc = smk_access(skp, obj_label, mode, NULL);
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if (rc == 0) {
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/*
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* If there is an entry in the task's rule list
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* it can further restrict access.
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*/
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may = smk_access_entry(skp->smk_known, obj_label,
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&tsp->smk_rules);
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if (may < 0)
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goto out_audit;
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if ((mode & may) == mode)
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goto out_audit;
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rc = -EACCES;
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}
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/*
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* Allow for priviliged to override policy.
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*/
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if (rc != 0 && smack_privileged(CAP_MAC_OVERRIDE))
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rc = 0;
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out_audit:
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#ifdef CONFIG_AUDIT
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if (a)
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smack_log(skp->smk_known, obj_label, mode, rc, a);
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#endif
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return rc;
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}
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#ifdef CONFIG_AUDIT
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/**
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* smack_str_from_perm : helper to transalate an int to a
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* readable string
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* @string : the string to fill
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* @access : the int
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*
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*/
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static inline void smack_str_from_perm(char *string, int access)
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{
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int i = 0;
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if (access & MAY_READ)
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string[i++] = 'r';
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if (access & MAY_WRITE)
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string[i++] = 'w';
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if (access & MAY_EXEC)
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string[i++] = 'x';
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if (access & MAY_APPEND)
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string[i++] = 'a';
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if (access & MAY_TRANSMUTE)
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string[i++] = 't';
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string[i] = '\0';
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}
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/**
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* smack_log_callback - SMACK specific information
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* will be called by generic audit code
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* @ab : the audit_buffer
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* @a : audit_data
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*
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*/
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static void smack_log_callback(struct audit_buffer *ab, void *a)
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{
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struct common_audit_data *ad = a;
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struct smack_audit_data *sad = ad->smack_audit_data;
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audit_log_format(ab, "lsm=SMACK fn=%s action=%s",
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ad->smack_audit_data->function,
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sad->result ? "denied" : "granted");
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audit_log_format(ab, " subject=");
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audit_log_untrustedstring(ab, sad->subject);
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audit_log_format(ab, " object=");
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audit_log_untrustedstring(ab, sad->object);
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audit_log_format(ab, " requested=%s", sad->request);
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}
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/**
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* smack_log - Audit the granting or denial of permissions.
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* @subject_label : smack label of the requester
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* @object_label : smack label of the object being accessed
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* @request: requested permissions
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* @result: result from smk_access
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* @a: auxiliary audit data
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*
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* Audit the granting or denial of permissions in accordance
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* with the policy.
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*/
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void smack_log(char *subject_label, char *object_label, int request,
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int result, struct smk_audit_info *ad)
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{
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char request_buffer[SMK_NUM_ACCESS_TYPE + 1];
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struct smack_audit_data *sad;
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struct common_audit_data *a = &ad->a;
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/* check if we have to log the current event */
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if (result != 0 && (log_policy & SMACK_AUDIT_DENIED) == 0)
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return;
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if (result == 0 && (log_policy & SMACK_AUDIT_ACCEPT) == 0)
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return;
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sad = a->smack_audit_data;
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if (sad->function == NULL)
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sad->function = "unknown";
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/* end preparing the audit data */
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smack_str_from_perm(request_buffer, request);
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sad->subject = subject_label;
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sad->object = object_label;
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sad->request = request_buffer;
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sad->result = result;
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common_lsm_audit(a, smack_log_callback, NULL);
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}
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#else /* #ifdef CONFIG_AUDIT */
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void smack_log(char *subject_label, char *object_label, int request,
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int result, struct smk_audit_info *ad)
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{
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}
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#endif
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DEFINE_MUTEX(smack_known_lock);
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struct hlist_head smack_known_hash[SMACK_HASH_SLOTS];
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/**
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* smk_insert_entry - insert a smack label into a hash map,
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*
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* this function must be called under smack_known_lock
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*/
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void smk_insert_entry(struct smack_known *skp)
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{
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unsigned int hash;
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struct hlist_head *head;
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hash = full_name_hash(skp->smk_known, strlen(skp->smk_known));
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head = &smack_known_hash[hash & (SMACK_HASH_SLOTS - 1)];
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hlist_add_head_rcu(&skp->smk_hashed, head);
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list_add_rcu(&skp->list, &smack_known_list);
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}
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/**
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* smk_find_entry - find a label on the list, return the list entry
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* @string: a text string that might be a Smack label
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*
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* Returns a pointer to the entry in the label list that
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* matches the passed string.
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*/
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struct smack_known *smk_find_entry(const char *string)
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{
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unsigned int hash;
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struct hlist_head *head;
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struct smack_known *skp;
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hash = full_name_hash(string, strlen(string));
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head = &smack_known_hash[hash & (SMACK_HASH_SLOTS - 1)];
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hlist_for_each_entry_rcu(skp, head, smk_hashed)
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if (strcmp(skp->smk_known, string) == 0)
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return skp;
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return NULL;
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}
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/**
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* smk_parse_smack - parse smack label from a text string
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* @string: a text string that might contain a Smack label
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* @len: the maximum size, or zero if it is NULL terminated.
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*
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* Returns a pointer to the clean label, or NULL
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*/
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char *smk_parse_smack(const char *string, int len)
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{
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char *smack;
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int i;
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if (len <= 0)
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len = strlen(string) + 1;
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/*
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* Reserve a leading '-' as an indicator that
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* this isn't a label, but an option to interfaces
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* including /smack/cipso and /smack/cipso2
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*/
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if (string[0] == '-')
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return NULL;
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for (i = 0; i < len; i++)
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if (string[i] > '~' || string[i] <= ' ' || string[i] == '/' ||
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string[i] == '"' || string[i] == '\\' || string[i] == '\'')
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break;
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if (i == 0 || i >= SMK_LONGLABEL)
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return NULL;
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smack = kzalloc(i + 1, GFP_KERNEL);
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if (smack != NULL) {
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strncpy(smack, string, i + 1);
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smack[i] = '\0';
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}
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return smack;
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}
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/**
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* smk_netlbl_mls - convert a catset to netlabel mls categories
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* @catset: the Smack categories
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* @sap: where to put the netlabel categories
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*
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* Allocates and fills attr.mls
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* Returns 0 on success, error code on failure.
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*/
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int smk_netlbl_mls(int level, char *catset, struct netlbl_lsm_secattr *sap,
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int len)
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{
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unsigned char *cp;
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unsigned char m;
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int cat;
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int rc;
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int byte;
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sap->flags |= NETLBL_SECATTR_MLS_CAT;
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sap->attr.mls.lvl = level;
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sap->attr.mls.cat = netlbl_secattr_catmap_alloc(GFP_ATOMIC);
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if (!sap->attr.mls.cat)
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return -ENOMEM;
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sap->attr.mls.cat->startbit = 0;
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for (cat = 1, cp = catset, byte = 0; byte < len; cp++, byte++)
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for (m = 0x80; m != 0; m >>= 1, cat++) {
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if ((m & *cp) == 0)
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continue;
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rc = netlbl_secattr_catmap_setbit(sap->attr.mls.cat,
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cat, GFP_ATOMIC);
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if (rc < 0) {
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netlbl_secattr_catmap_free(sap->attr.mls.cat);
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return rc;
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}
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}
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|
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return 0;
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}
|
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|
|
/**
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* smk_import_entry - import a label, return the list entry
|
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* @string: a text string that might be a Smack label
|
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* @len: the maximum size, or zero if it is NULL terminated.
|
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*
|
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* Returns a pointer to the entry in the label list that
|
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* matches the passed string, adding it if necessary.
|
|
*/
|
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struct smack_known *smk_import_entry(const char *string, int len)
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{
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struct smack_known *skp;
|
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char *smack;
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int slen;
|
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int rc;
|
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|
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smack = smk_parse_smack(string, len);
|
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if (smack == NULL)
|
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return NULL;
|
|
|
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mutex_lock(&smack_known_lock);
|
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|
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skp = smk_find_entry(smack);
|
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if (skp != NULL)
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goto freeout;
|
|
|
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skp = kzalloc(sizeof(*skp), GFP_KERNEL);
|
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if (skp == NULL)
|
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goto freeout;
|
|
|
|
skp->smk_known = smack;
|
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skp->smk_secid = smack_next_secid++;
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|
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;
|
|
}
|
|
|
|
/**
|
|
* 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.
|
|
*
|
|
* Returns a pointer to the label in the label list that
|
|
* matches the passed string, adding it if necessary.
|
|
*/
|
|
char *smk_import(const char *string, int len)
|
|
{
|
|
struct smack_known *skp;
|
|
|
|
/* 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;
|
|
}
|
|
|
|
/**
|
|
* 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_invalid;
|
|
}
|
|
|
|
/**
|
|
* smack_to_secid - find the secid associated with a Smack label
|
|
* @smack: the Smack label
|
|
*
|
|
* Returns the appropriate secid if there is one,
|
|
* otherwise 0
|
|
*/
|
|
u32 smack_to_secid(const char *smack)
|
|
{
|
|
struct smack_known *skp = smk_find_entry(smack);
|
|
|
|
if (skp == NULL)
|
|
return 0;
|
|
return skp->smk_secid;
|
|
}
|