From b4b7ff4b08e691656c9d77c758fc355833128ac0 Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Wed, 20 Jan 2016 14:01:31 -0300
Subject: Linux-libre 4.4-gnu

---
 security/smack/smack_lsm.c | 67 ++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 62 insertions(+), 5 deletions(-)

(limited to 'security/smack/smack_lsm.c')

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 996c88956..ff81026f6 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -52,7 +52,7 @@
 #define SMK_SENDING	2
 
 #ifdef SMACK_IPV6_PORT_LABELING
-LIST_HEAD(smk_ipv6_port_list);
+static LIST_HEAD(smk_ipv6_port_list);
 #endif
 static struct kmem_cache *smack_inode_cache;
 int smack_enabled;
@@ -326,6 +326,7 @@ static struct task_smack *new_task_smack(struct smack_known *task,
 	tsp->smk_task = task;
 	tsp->smk_forked = forked;
 	INIT_LIST_HEAD(&tsp->smk_rules);
+	INIT_LIST_HEAD(&tsp->smk_relabel);
 	mutex_init(&tsp->smk_rules_lock);
 
 	return tsp;
@@ -360,6 +361,35 @@ static int smk_copy_rules(struct list_head *nhead, struct list_head *ohead,
 	return rc;
 }
 
+/**
+ * smk_copy_relabel - copy smk_relabel labels list
+ * @nhead: new rules header pointer
+ * @ohead: old rules header pointer
+ * @gfp: type of the memory for the allocation
+ *
+ * Returns 0 on success, -ENOMEM on error
+ */
+static int smk_copy_relabel(struct list_head *nhead, struct list_head *ohead,
+				gfp_t gfp)
+{
+	struct smack_known_list_elem *nklep;
+	struct smack_known_list_elem *oklep;
+
+	INIT_LIST_HEAD(nhead);
+
+	list_for_each_entry(oklep, ohead, list) {
+		nklep = kzalloc(sizeof(struct smack_known_list_elem), gfp);
+		if (nklep == NULL) {
+			smk_destroy_label_list(nhead);
+			return -ENOMEM;
+		}
+		nklep->smk_label = oklep->smk_label;
+		list_add(&nklep->list, nhead);
+	}
+
+	return 0;
+}
+
 /**
  * smk_ptrace_mode - helper function for converting PTRACE_MODE_* into MAY_*
  * @mode - input mode in form of PTRACE_MODE_*
@@ -1922,6 +1952,8 @@ static void smack_cred_free(struct cred *cred)
 		return;
 	cred->security = NULL;
 
+	smk_destroy_label_list(&tsp->smk_relabel);
+
 	list_for_each_safe(l, n, &tsp->smk_rules) {
 		rp = list_entry(l, struct smack_rule, list);
 		list_del(&rp->list);
@@ -1953,6 +1985,11 @@ static int smack_cred_prepare(struct cred *new, const struct cred *old,
 	if (rc != 0)
 		return rc;
 
+	rc = smk_copy_relabel(&new_tsp->smk_relabel, &old_tsp->smk_relabel,
+				gfp);
+	if (rc != 0)
+		return rc;
+
 	new->security = new_tsp;
 	return 0;
 }
@@ -3354,6 +3391,9 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
 			 */
 			isp->smk_inode = smk_of_current();
 			break;
+		case PIPEFS_MAGIC:
+			isp->smk_inode = smk_of_current();
+			break;
 		default:
 			isp->smk_inode = sbsp->smk_root;
 			break;
@@ -3549,9 +3589,11 @@ static int smack_getprocattr(struct task_struct *p, char *name, char **value)
 static int smack_setprocattr(struct task_struct *p, char *name,
 			     void *value, size_t size)
 {
-	struct task_smack *tsp;
+	struct task_smack *tsp = current_security();
 	struct cred *new;
 	struct smack_known *skp;
+	struct smack_known_list_elem *sklep;
+	int rc;
 
 	/*
 	 * Changing another process' Smack value is too dangerous
@@ -3560,7 +3602,7 @@ static int smack_setprocattr(struct task_struct *p, char *name,
 	if (p != current)
 		return -EPERM;
 
-	if (!smack_privileged(CAP_MAC_ADMIN))
+	if (!smack_privileged(CAP_MAC_ADMIN) && list_empty(&tsp->smk_relabel))
 		return -EPERM;
 
 	if (value == NULL || size == 0 || size >= SMK_LONGLABEL)
@@ -3579,12 +3621,27 @@ static int smack_setprocattr(struct task_struct *p, char *name,
 	if (skp == &smack_known_web)
 		return -EPERM;
 
+	if (!smack_privileged(CAP_MAC_ADMIN)) {
+		rc = -EPERM;
+		list_for_each_entry(sklep, &tsp->smk_relabel, list)
+			if (sklep->smk_label == skp) {
+				rc = 0;
+				break;
+			}
+		if (rc)
+			return rc;
+	}
+
 	new = prepare_creds();
 	if (new == NULL)
 		return -ENOMEM;
 
 	tsp = new->security;
 	tsp->smk_task = skp;
+	/*
+	 * process can change its label only once
+	 */
+	smk_destroy_label_list(&tsp->smk_relabel);
 
 	commit_creds(new);
 	return size;
@@ -4708,8 +4765,6 @@ static __init int smack_init(void)
 	if (!security_module_enable("smack"))
 		return 0;
 
-	smack_enabled = 1;
-
 	smack_inode_cache = KMEM_CACHE(inode_smack, 0);
 	if (!smack_inode_cache)
 		return -ENOMEM;
@@ -4721,6 +4776,8 @@ static __init int smack_init(void)
 		return -ENOMEM;
 	}
 
+	smack_enabled = 1;
+
 	pr_info("Smack:  Initializing.\n");
 #ifdef CONFIG_SECURITY_SMACK_NETFILTER
 	pr_info("Smack:  Netfilter enabled.\n");
-- 
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