[TOMOYO #6 retry 13/21] environment variable name check functions.

[Kentaro Takeda]

TOMOYO Linux checks environment variable's names passed to execve()
because some envorinment variables affects to the behavior of program
like argv[0].

Each permission can be automatically accumulated into
the policy of each domain using 'learning mode'.

Signed-off-by: Kentaro Takeda <takedakn@xxxxxxxxxxxxx>
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
---
 security/tomoyo/environ.c |  274 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 274 insertions(+)

--- /dev/null
+++ linux-2.6-mm/security/tomoyo/environ.c
@@ -0,0 +1,274 @@
+/*
+ * security/tomoyo/environ.c
+ *
+ * Environment variable access control functions for TOMOYO Linux.
+ */
+
+#include "tomoyo.h"
+#include "realpath.h"
+
+/*************************  AUDIT FUNCTIONS  *************************/
+
+static int tmy_audit_env_log(const char *env,
+			     const bool is_granted,
+			     const u8 profile,
+			     const unsigned int mode)
+{
+	char *buf;
+	int len;
+
+	if (is_granted) {
+		if (!tmy_audit_grant())
+			return 0;
+	} else {
+		if (!tmy_audit_reject())
+			return 0;
+	}
+
+	len = strlen(env) + 8;
+	buf = tmy_init_audit_log(&len, profile, mode);
+
+	if (!buf)
+		return -ENOMEM;
+
+	tmy_sncatprintf(buf, len - 1, TMY_ALLOW_ENV "%s", env);
+
+	return tmy_write_audit_log(buf, is_granted);
+}
+
+/***** The structure for globally usable environments. *****/
+
+struct globally_usable_env_entry {
+	struct list_head list;
+	const struct path_info *env;
+	bool is_deleted;
+};
+
+/*******************  GLOBALLY USABLE ENVIRONMENT HANDLER  ********************/
+
+static LIST_HEAD(globally_usable_env_list);
+
+static int tmy_add_globally_usable_env_entry(const char *env,
+					     const bool is_delete)
+{
+	struct globally_usable_env_entry *new_entry;
+	struct globally_usable_env_entry *ptr;
+	static DEFINE_MUTEX(lock);
+	const struct path_info *saved_env;
+	int error = -ENOMEM;
+	if (!tmy_correct_path(env, 0, 0, 0, __FUNCTION__))
+		return -EINVAL;
+	saved_env = tmy_save_name(env);
+	if (!saved_env)
+		return -ENOMEM;
+	mutex_lock(&lock);
+	list_for_each_entry(ptr, &globally_usable_env_list, list) {
+		if (ptr->env == saved_env) {
+			ptr->is_deleted = is_delete;
+			error = 0;
+			goto out;
+		}
+	}
+	if (is_delete) {
+		error = -ENOENT;
+		goto out;
+	}
+	new_entry = tmy_alloc_element(sizeof(*new_entry));
+	if (!new_entry)
+		goto out;
+	new_entry->env = saved_env;
+	list_add_tail_mb(&new_entry->list, &globally_usable_env_list);
+	error = 0;
+out:
+	mutex_unlock(&lock);
+	return error;
+}
+
+static bool tmy_is_globally_usable_env(const struct path_info *env)
+{
+	struct globally_usable_env_entry *ptr;
+	list_for_each_entry(ptr, &globally_usable_env_list, list) {
+		if (!ptr->is_deleted && tmy_path_match(env, ptr->env))
+			return 1;
+	}
+	return 0;
+}
+
+int tmy_add_globally_usable_env_policy(char *env, const bool is_delete)
+{
+	return tmy_add_globally_usable_env_entry(env, is_delete);
+}
+
+int tmy_read_globally_usable_env_policy(struct io_buffer *head)
+{
+	struct list_head *pos;
+	list_for_each_cookie(pos, head->read_var2, &globally_usable_env_list) {
+		struct globally_usable_env_entry *ptr;
+		ptr = list_entry(pos, struct globally_usable_env_entry, list);
+		if (ptr->is_deleted)
+			continue;
+		if (tmy_io_printf(head, TMY_ALLOW_ENV "%s\n",
+				  ptr->env->name))
+			return -ENOMEM;
+	}
+	return 0;
+}
+
+/******************  ENVIRONMENT VARIABLE Checking HANDLER  *******************/
+
+static int tmy_add_env_entry(const char *env,
+			     struct domain_info *domain,
+			     const struct condition_list *cond,
+			     const bool is_delete)
+{
+	struct acl_info *ptr;
+	struct env_acl *acl;
+	const struct path_info *saved_env;
+	int error = -ENOMEM;
+
+	if (!tmy_correct_path(env, 0, 0, 0, __FUNCTION__))
+		return -EINVAL;
+
+	saved_env = tmy_save_name(env);
+	if (!saved_env)
+		return -ENOMEM;
+	if (!is_delete && tmy_is_globally_usable_env(saved_env))
+		return 0;
+
+	mutex_lock(&domain_acl_lock);
+
+	if (is_delete)
+		goto remove;
+
+	list_for_each_entry(ptr, &domain->acl_info_list, list) {
+		acl = container_of(ptr, struct env_acl, head);
+		if (ptr->type == TMY_TYPE_ENV_ACL && ptr->cond == cond &&
+		    acl->env == saved_env) {
+			ptr->is_deleted = 0;
+			/* Found. Nothing to do. */
+			error = 0;
+			goto ok;
+		}
+	}
+
+	/* Not found. Append it to the tail. */
+	acl = tmy_alloc_element(sizeof(*acl));
+	if (!acl)
+		goto ok;
+
+	acl->head.type = TMY_TYPE_ENV_ACL;
+	acl->head.cond = cond;
+	acl->env = saved_env;
+	error = tmy_add_acl(domain, &acl->head);
+	goto ok;
+remove: ;
+	error = -ENOENT;
+	list_for_each_entry(ptr, &domain->acl_info_list, list) {
+		acl = container_of(ptr, struct env_acl, head);
+		if (ptr->type != TMY_TYPE_ENV_ACL ||
+		    ptr->cond != cond || ptr->is_deleted ||
+		    acl->env != saved_env)
+			continue;
+
+		error = tmy_del_acl(ptr);
+		break;
+	}
+ok: ;
+	mutex_unlock(&domain_acl_lock);
+
+	return error;
+}
+
+static int tmy_env_acl(const char *env_)
+{
+	const struct domain_info *domain = TMY_SECURITY->domain;
+	int error = -EPERM;
+	struct acl_info *ptr;
+	struct path_info env;
+
+	if (!tmy_flags(TMY_MAC_FOR_ENV))
+		return 0;
+
+	env.name = env_;
+	tmy_fill_path_info(&env);
+	if (tmy_is_globally_usable_env(&env))
+		return 0;
+
+	list_for_each_entry(ptr, &domain->acl_info_list, list) {
+		struct env_acl *acl;
+		acl = container_of(ptr, struct env_acl, head);
+
+		if (ptr->type == TMY_TYPE_ENV_ACL &&
+		    ptr->is_deleted == 0 &&
+		    tmy_check_condition(ptr->cond, NULL) == 0 &&
+		    tmy_path_match(&env, acl->env)) {
+			error = 0;
+			break;
+		}
+	}
+
+	return error;
+}
+
+/**
+ * tmy_env_perm - check for environment variable permission.
+ * @env:    pointer to environment variable.
+ *
+ * Returns zero if permission granted.
+ * Returns nonzero if permission denied.
+ */
+int tmy_env_perm(const char *env, const u8 profile, const unsigned int mode)
+{
+	int error = 0;
+	const bool is_enforce = (mode == 3);
+
+	if (!mode)
+		return 0;
+	if (!env || !*env)
+		return 0;
+
+	error = tmy_env_acl(env);
+
+	tmy_audit_env_log(env, !error, profile, mode);
+
+	if (error) {
+		struct domain_info * const domain = TMY_SECURITY->domain;
+
+		if (tmy_flags(TMY_VERBOSE))
+			tmy_audit("TOMOYO-%s: Environment variable %s "
+				  "denied for %s\n",
+				  tmy_getmsg(is_enforce), env,
+				  tmy_lastname(domain));
+
+		if (is_enforce)
+			error = tmy_supervisor("%s\n" TMY_ALLOW_ENV "%s\n",
+					       domain->domainname->name, env);
+
+		else if (mode == 1 && tmy_quota())
+			tmy_add_env_entry(env, domain, NULL, 0);
+
+		if (!is_enforce)
+			error = 0;
+	}
+
+	return error;
+}
+
+/**
+ * tmy_add_env_policy - add or delete environment variable policy.
+ * @data:      a line to parse.
+ * @domain:    pointer to "struct domain_info".
+ * @cond:      pointer to "struct condition_list". May be NULL.
+ * @is_delete: is this delete request?
+ *
+ * Returns zero on success.
+ * Returns nonzero on failure.
+ */
+int tmy_add_env_policy(char *data,
+			 struct domain_info *domain,
+			 const struct condition_list *cond,
+			 const bool is_delete)
+{
+	return tmy_add_env_entry(data, domain, cond,
+				 is_delete);
+}

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