TOMOYO: Allow domain transition without execve().
To be able to split permissions for Apache's CGI programs which are executed
without execve(), add special domain transition which is performed by writing
a TOMOYO's domainname to /sys/kernel/security/tomoyo/self_domain interface.
This is an API for TOMOYO-aware userland applications. However, since I expect
TOMOYO and other LSM modules to run in parallel, this patch does not use
/proc/self/attr/ interface in order to avoid conflicts with other LSM modules
when it became possible to run multiple LSM modules in parallel.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/security/tomoyo/securityfs_if.c b/security/tomoyo/securityfs_if.c
index a49c3bf..d08296a 100644
--- a/security/tomoyo/securityfs_if.c
+++ b/security/tomoyo/securityfs_if.c
@@ -8,6 +8,124 @@
#include "common.h"
/**
+ * tomoyo_check_task_acl - Check permission for task operation.
+ *
+ * @r: Pointer to "struct tomoyo_request_info".
+ * @ptr: Pointer to "struct tomoyo_acl_info".
+ *
+ * Returns true if granted, false otherwise.
+ */
+static bool tomoyo_check_task_acl(struct tomoyo_request_info *r,
+ const struct tomoyo_acl_info *ptr)
+{
+ const struct tomoyo_task_acl *acl = container_of(ptr, typeof(*acl),
+ head);
+ return !tomoyo_pathcmp(r->param.task.domainname, acl->domainname);
+}
+
+/**
+ * tomoyo_write_self - write() for /sys/kernel/security/tomoyo/self_domain interface.
+ *
+ * @file: Pointer to "struct file".
+ * @buf: Domainname to transit to.
+ * @count: Size of @buf.
+ * @ppos: Unused.
+ *
+ * Returns @count on success, negative value otherwise.
+ *
+ * If domain transition was permitted but the domain transition failed, this
+ * function returns error rather than terminating current thread with SIGKILL.
+ */
+static ssize_t tomoyo_write_self(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ char *data;
+ int error;
+ if (!count || count >= TOMOYO_EXEC_TMPSIZE - 10)
+ return -ENOMEM;
+ data = kzalloc(count + 1, GFP_NOFS);
+ if (!data)
+ return -ENOMEM;
+ if (copy_from_user(data, buf, count)) {
+ error = -EFAULT;
+ goto out;
+ }
+ tomoyo_normalize_line(data);
+ if (tomoyo_correct_domain(data)) {
+ const int idx = tomoyo_read_lock();
+ struct tomoyo_path_info name;
+ struct tomoyo_request_info r;
+ name.name = data;
+ tomoyo_fill_path_info(&name);
+ /* Check "task manual_domain_transition" permission. */
+ tomoyo_init_request_info(&r, NULL, TOMOYO_MAC_FILE_EXECUTE);
+ r.param_type = TOMOYO_TYPE_MANUAL_TASK_ACL;
+ r.param.task.domainname = &name;
+ tomoyo_check_acl(&r, tomoyo_check_task_acl);
+ if (!r.granted)
+ error = -EPERM;
+ else {
+ struct tomoyo_domain_info *new_domain =
+ tomoyo_assign_domain(data, true);
+ if (!new_domain) {
+ error = -ENOENT;
+ } else {
+ struct cred *cred = prepare_creds();
+ if (!cred) {
+ error = -ENOMEM;
+ } else {
+ struct tomoyo_domain_info *old_domain =
+ cred->security;
+ cred->security = new_domain;
+ atomic_inc(&new_domain->users);
+ atomic_dec(&old_domain->users);
+ commit_creds(cred);
+ error = 0;
+ }
+ }
+ }
+ tomoyo_read_unlock(idx);
+ } else
+ error = -EINVAL;
+out:
+ kfree(data);
+ return error ? error : count;
+}
+
+/**
+ * tomoyo_read_self - read() for /sys/kernel/security/tomoyo/self_domain interface.
+ *
+ * @file: Pointer to "struct file".
+ * @buf: Domainname which current thread belongs to.
+ * @count: Size of @buf.
+ * @ppos: Bytes read by now.
+ *
+ * Returns read size on success, negative value otherwise.
+ */
+static ssize_t tomoyo_read_self(struct file *file, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ const char *domain = tomoyo_domain()->domainname->name;
+ loff_t len = strlen(domain);
+ loff_t pos = *ppos;
+ if (pos >= len || !count)
+ return 0;
+ len -= pos;
+ if (count < len)
+ len = count;
+ if (copy_to_user(buf, domain + pos, len))
+ return -EFAULT;
+ *ppos += len;
+ return len;
+}
+
+/* Operations for /sys/kernel/security/tomoyo/self_domain interface. */
+static const struct file_operations tomoyo_self_operations = {
+ .write = tomoyo_write_self,
+ .read = tomoyo_read_self,
+};
+
+/**
* tomoyo_open - open() for /sys/kernel/security/tomoyo/ interface.
*
* @inode: Pointer to "struct inode".
@@ -135,8 +253,6 @@
TOMOYO_EXCEPTIONPOLICY);
tomoyo_create_entry("audit", 0400, tomoyo_dir,
TOMOYO_AUDIT);
- tomoyo_create_entry("self_domain", 0400, tomoyo_dir,
- TOMOYO_SELFDOMAIN);
tomoyo_create_entry(".process_status", 0600, tomoyo_dir,
TOMOYO_PROCESS_STATUS);
tomoyo_create_entry("stat", 0644, tomoyo_dir,
@@ -147,6 +263,8 @@
TOMOYO_MANAGER);
tomoyo_create_entry("version", 0400, tomoyo_dir,
TOMOYO_VERSION);
+ securityfs_create_file("self_domain", 0666, tomoyo_dir, NULL,
+ &tomoyo_self_operations);
return 0;
}