Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 345 insertions, 0 deletions

diff --git a/security/safesetid/securityfs.c b/security/safesetid/securityfs.c
new file mode 100644
index 000000000..25310468b
--- /dev/null
+++ b/security/safesetid/securityfs.c
@@ -0,0 +1,345 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * SafeSetID Linux Security Module
+ *
+ * Author: Micah Morton <mortonm@chromium.org>
+ *
+ * Copyright (C) 2018 The Chromium OS Authors.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#define pr_fmt(fmt) "SafeSetID: " fmt
+
+#include <linux/security.h>
+#include <linux/cred.h>
+
+#include "lsm.h"
+
+static DEFINE_MUTEX(uid_policy_update_lock);
+static DEFINE_MUTEX(gid_policy_update_lock);
+
+/*
+ * In the case the input buffer contains one or more invalid IDs, the kid_t
+ * variables pointed to by @parent and @child will get updated but this
+ * function will return an error.
+ * Contents of @buf may be modified.
+ */
+static int parse_policy_line(struct file *file, char *buf,
+	struct setid_rule *rule)
+{
+	char *child_str;
+	int ret;
+	u32 parsed_parent, parsed_child;
+
+	/* Format of |buf| string should be <UID>:<UID> or <GID>:<GID> */
+	child_str = strchr(buf, ':');
+	if (child_str == NULL)
+		return -EINVAL;
+	*child_str = '\0';
+	child_str++;
+
+	ret = kstrtou32(buf, 0, &parsed_parent);
+	if (ret)
+		return ret;
+
+	ret = kstrtou32(child_str, 0, &parsed_child);
+	if (ret)
+		return ret;
+
+	if (rule->type == UID){
+		rule->src_id.uid = make_kuid(file->f_cred->user_ns, parsed_parent);
+		rule->dst_id.uid = make_kuid(file->f_cred->user_ns, parsed_child);
+		if (!uid_valid(rule->src_id.uid) || !uid_valid(rule->dst_id.uid))
+			return -EINVAL;
+	} else if (rule->type == GID){
+		rule->src_id.gid = make_kgid(file->f_cred->user_ns, parsed_parent);
+		rule->dst_id.gid = make_kgid(file->f_cred->user_ns, parsed_child);
+		if (!gid_valid(rule->src_id.gid) || !gid_valid(rule->dst_id.gid))
+			return -EINVAL;
+	} else {
+		/* Error, rule->type is an invalid type */
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static void __release_ruleset(struct rcu_head *rcu)
+{
+	struct setid_ruleset *pol =
+		container_of(rcu, struct setid_ruleset, rcu);
+	int bucket;
+	struct setid_rule *rule;
+	struct hlist_node *tmp;
+
+	hash_for_each_safe(pol->rules, bucket, tmp, rule, next)
+		kfree(rule);
+	kfree(pol->policy_str);
+	kfree(pol);
+}
+
+static void release_ruleset(struct setid_ruleset *pol){
+	call_rcu(&pol->rcu, __release_ruleset);
+}
+
+static void insert_rule(struct setid_ruleset *pol, struct setid_rule *rule)
+{
+	if (pol->type == UID)
+		hash_add(pol->rules, &rule->next, __kuid_val(rule->src_id.uid));
+	else if (pol->type == GID)
+		hash_add(pol->rules, &rule->next, __kgid_val(rule->src_id.gid));
+	else /* Error, pol->type is neither UID or GID */
+		return;
+}
+
+static int verify_ruleset(struct setid_ruleset *pol)
+{
+	int bucket;
+	struct setid_rule *rule, *nrule;
+	int res = 0;
+
+	hash_for_each(pol->rules, bucket, rule, next) {
+		if (_setid_policy_lookup(pol, rule->dst_id, INVALID_ID) == SIDPOL_DEFAULT) {
+			if (pol->type == UID) {
+				pr_warn("insecure policy detected: uid %d is constrained but transitively unconstrained through uid %d\n",
+					__kuid_val(rule->src_id.uid),
+					__kuid_val(rule->dst_id.uid));
+			} else if (pol->type == GID) {
+				pr_warn("insecure policy detected: gid %d is constrained but transitively unconstrained through gid %d\n",
+					__kgid_val(rule->src_id.gid),
+					__kgid_val(rule->dst_id.gid));
+			} else { /* pol->type is an invalid type */
+				res = -EINVAL;
+				return res;
+			}
+			res = -EINVAL;
+
+			/* fix it up */
+			nrule = kmalloc(sizeof(struct setid_rule), GFP_KERNEL);
+			if (!nrule)
+				return -ENOMEM;
+			if (pol->type == UID){
+				nrule->src_id.uid = rule->dst_id.uid;
+				nrule->dst_id.uid = rule->dst_id.uid;
+				nrule->type = UID;
+			} else { /* pol->type must be GID if we've made it to here */
+				nrule->src_id.gid = rule->dst_id.gid;
+				nrule->dst_id.gid = rule->dst_id.gid;
+				nrule->type = GID;
+			}
+			insert_rule(pol, nrule);
+		}
+	}
+	return res;
+}
+
+static ssize_t handle_policy_update(struct file *file,
+				    const char __user *ubuf, size_t len, enum setid_type policy_type)
+{
+	struct setid_ruleset *pol;
+	char *buf, *p, *end;
+	int err;
+
+	pol = kmalloc(sizeof(struct setid_ruleset), GFP_KERNEL);
+	if (!pol)
+		return -ENOMEM;
+	pol->policy_str = NULL;
+	pol->type = policy_type;
+	hash_init(pol->rules);
+
+	p = buf = memdup_user_nul(ubuf, len);
+	if (IS_ERR(buf)) {
+		err = PTR_ERR(buf);
+		goto out_free_pol;
+	}
+	pol->policy_str = kstrdup(buf, GFP_KERNEL);
+	if (pol->policy_str == NULL) {
+		err = -ENOMEM;
+		goto out_free_buf;
+	}
+
+	/* policy lines, including the last one, end with \n */
+	while (*p != '\0') {
+		struct setid_rule *rule;
+
+		end = strchr(p, '\n');
+		if (end == NULL) {
+			err = -EINVAL;
+			goto out_free_buf;
+		}
+		*end = '\0';
+
+		rule = kmalloc(sizeof(struct setid_rule), GFP_KERNEL);
+		if (!rule) {
+			err = -ENOMEM;
+			goto out_free_buf;
+		}
+
+		rule->type = policy_type;
+		err = parse_policy_line(file, p, rule);
+		if (err)
+			goto out_free_rule;
+
+		if (_setid_policy_lookup(pol, rule->src_id, rule->dst_id) == SIDPOL_ALLOWED) {
+			pr_warn("bad policy: duplicate entry\n");
+			err = -EEXIST;
+			goto out_free_rule;
+		}
+
+		insert_rule(pol, rule);
+		p = end + 1;
+		continue;
+
+out_free_rule:
+		kfree(rule);
+		goto out_free_buf;
+	}
+
+	err = verify_ruleset(pol);
+	/* bogus policy falls through after fixing it up */
+	if (err && err != -EINVAL)
+		goto out_free_buf;
+
+	/*
+	 * Everything looks good, apply the policy and release the old one.
+	 * What we really want here is an xchg() wrapper for RCU, but since that
+	 * doesn't currently exist, just use a spinlock for now.
+	 */
+	if (policy_type == UID) {
+		mutex_lock(&uid_policy_update_lock);
+		pol = rcu_replace_pointer(safesetid_setuid_rules, pol,
+					  lockdep_is_held(&uid_policy_update_lock));
+		mutex_unlock(&uid_policy_update_lock);
+	} else if (policy_type == GID) {
+		mutex_lock(&gid_policy_update_lock);
+		pol = rcu_replace_pointer(safesetid_setgid_rules, pol,
+					  lockdep_is_held(&gid_policy_update_lock));
+		mutex_unlock(&gid_policy_update_lock);
+	} else {
+		/* Error, policy type is neither UID or GID */
+		pr_warn("error: bad policy type");
+	}
+	err = len;
+
+out_free_buf:
+	kfree(buf);
+out_free_pol:
+	if (pol)
+		release_ruleset(pol);
+	return err;
+}
+
+static ssize_t safesetid_uid_file_write(struct file *file,
+				    const char __user *buf,
+				    size_t len,
+				    loff_t *ppos)
+{
+	if (!file_ns_capable(file, &init_user_ns, CAP_MAC_ADMIN))
+		return -EPERM;
+
+	if (*ppos != 0)
+		return -EINVAL;
+
+	return handle_policy_update(file, buf, len, UID);
+}
+
+static ssize_t safesetid_gid_file_write(struct file *file,
+				    const char __user *buf,
+				    size_t len,
+				    loff_t *ppos)
+{
+	if (!file_ns_capable(file, &init_user_ns, CAP_MAC_ADMIN))
+		return -EPERM;
+
+	if (*ppos != 0)
+		return -EINVAL;
+
+	return handle_policy_update(file, buf, len, GID);
+}
+
+static ssize_t safesetid_file_read(struct file *file, char __user *buf,
+				   size_t len, loff_t *ppos, struct mutex *policy_update_lock, struct __rcu setid_ruleset* ruleset)
+{
+	ssize_t res = 0;
+	struct setid_ruleset *pol;
+	const char *kbuf;
+
+	mutex_lock(policy_update_lock);
+	pol = rcu_dereference_protected(ruleset, lockdep_is_held(policy_update_lock));
+	if (pol) {
+		kbuf = pol->policy_str;
+		res = simple_read_from_buffer(buf, len, ppos,
+					      kbuf, strlen(kbuf));
+	}
+	mutex_unlock(policy_update_lock);
+
+	return res;
+}
+
+static ssize_t safesetid_uid_file_read(struct file *file, char __user *buf,
+				   size_t len, loff_t *ppos)
+{
+	return safesetid_file_read(file, buf, len, ppos,
+				   &uid_policy_update_lock, safesetid_setuid_rules);
+}
+
+static ssize_t safesetid_gid_file_read(struct file *file, char __user *buf,
+				   size_t len, loff_t *ppos)
+{
+	return safesetid_file_read(file, buf, len, ppos,
+				   &gid_policy_update_lock, safesetid_setgid_rules);
+}
+
+
+
+static const struct file_operations safesetid_uid_file_fops = {
+	.read = safesetid_uid_file_read,
+	.write = safesetid_uid_file_write,
+};
+
+static const struct file_operations safesetid_gid_file_fops = {
+	.read = safesetid_gid_file_read,
+	.write = safesetid_gid_file_write,
+};
+
+static int __init safesetid_init_securityfs(void)
+{
+	int ret;
+	struct dentry *policy_dir;
+	struct dentry *uid_policy_file;
+	struct dentry *gid_policy_file;
+
+	if (!safesetid_initialized)
+		return 0;
+
+	policy_dir = securityfs_create_dir("safesetid", NULL);
+	if (IS_ERR(policy_dir)) {
+		ret = PTR_ERR(policy_dir);
+		goto error;
+	}
+
+	uid_policy_file = securityfs_create_file("uid_allowlist_policy", 0600,
+			policy_dir, NULL, &safesetid_uid_file_fops);
+	if (IS_ERR(uid_policy_file)) {
+		ret = PTR_ERR(uid_policy_file);
+		goto error;
+	}
+
+	gid_policy_file = securityfs_create_file("gid_allowlist_policy", 0600,
+			policy_dir, NULL, &safesetid_gid_file_fops);
+	if (IS_ERR(gid_policy_file)) {
+		ret = PTR_ERR(gid_policy_file);
+		goto error;
+	}
+
+
+	return 0;
+
+error:
+	securityfs_remove(policy_dir);
+	return ret;
+}
+fs_initcall(safesetid_init_securityfs);