Domain transition functions for TOMOYO Linux.
Every process belongs to a domain in TOMOYO Linux.
Domain transition occurs when execve(2) is called
and the domain is expressed as 'process invocation history',
such as '<kernel> /sbin/init /etc/init.d/rc'.
Domain information is stored in task_struct->security.

Signed-off-by: Kentaro Takeda <[EMAIL PROTECTED]>
Signed-off-by: Tetsuo Handa <[EMAIL PROTECTED]>
---
 security/tomoyo/domain.c | 1259 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 1259 insertions(+)

--- /dev/null   1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6/security/tomoyo/domain.c  2007-10-11 15:53:12.000000000 +0900
@@ -0,0 +1,1259 @@
+/*
+ * security/tomoyo/domain.c
+ *
+ * Domain transition functions for TOMOYO Linux.
+ */
+
+#include "tomoyo.h"
+#include "realpath.h"
+#include <linux/highmem.h>
+#include <linux/binfmts.h>
+
+/*************************  VARIABLES  *************************/
+
+struct domain_info KERNEL_DOMAIN;
+
+/* Lock for appending domain's ACL. */
+DEFINE_MUTEX(domain_acl_lock);
+
+/* Domain creation lock. */
+static DEFINE_MUTEX(new_domain_assign_lock);
+
+/***** The structure for program files to force domain reconstruction. *****/
+
+struct domain_initializer_entry {
+       struct list_head list;
+       const struct path_info *domainname;    /* This may be NULL */
+       const struct path_info *program;
+       u8 is_deleted;
+       u8 is_not;
+       u8 is_last_name;
+};
+
+/***** The structure for domains to not to transit domains. *****/
+
+struct domain_keeper_entry {
+       struct list_head list;
+       const struct path_info *domainname;
+       const struct path_info *program;       /* This may be NULL */
+       u8 is_deleted;
+       u8 is_not;
+       u8 is_last_name;
+};
+
+/***** The structure for program files that should be aggregated. *****/
+
+struct aggregator_entry {
+       struct list_head list;
+       const struct path_info *original_name;
+       const struct path_info *aggregated_name;
+       u8 is_deleted;
+};
+
+/***** The structure for program files that should be aliased. *****/
+
+struct alias_entry {
+       struct list_head list;
+       const struct path_info *original_name;
+       const struct path_info *aliased_name;
+       u8 is_deleted;
+};
+
+/*************************  UTILITY FUNCTIONS  *************************/
+
+/**
+ * tmy_is_domain_def - check if the line is likely a domain definition.
+ * @buffer: the line to check.
+ *
+ * Returns nonzero if @buffer is likely a domain definition.
+ * Returns zero otherwise.
+ *
+ * For complete validation check, use tmy_is_correct_domain().
+ */
+int tmy_is_domain_def(const unsigned char *buffer)
+{
+       return strncmp(buffer, TMY_ROOT_NAME, TMY_ROOT_NAME_LEN) == 0;
+}
+
+/**
+ * tmy_add_acl - add an entry to a domain.
+ * @domain: pointer to "struct domain_info".
+ * @acl: pointer to "struct acl_info" to add.
+ *
+ * Returns zero.
+ */
+int tmy_add_acl(struct domain_info *domain, struct acl_info *acl)
+{
+       INIT_LIST_HEAD(&acl->list);
+       mb(); /* Avoid out-of-order execution. */
+       /* RCU: Protected by domain_acl_lock. */
+       list_add_tail_rcu(&acl->list, &domain->acl_info_list);
+       tmy_update_counter(TMY_UPDATE_DOMAINPOLICY);
+       return 0;
+}
+
+/**
+ * tmy_del_acl - remove an entry from a domain
+ * @ptr: pointer to "struct acl_info" to remove.
+ *
+ * Returns zero.
+ *
+ * TOMOYO Linux doesn't free memory used by policy because policies are not
+ * so frequently changed after entring into enforcing mode.
+ */
+int tmy_del_acl(struct acl_info *ptr)
+{
+       ptr->is_deleted = 1;
+       tmy_update_counter(TMY_UPDATE_DOMAINPOLICY);
+       return 0;
+}
+
+/************************  DOMAIN INITIALIZER HANDLER  
************************/
+
+static LIST_HEAD(domain_initializer_list);
+
+/* Update domain initializer list. */
+static int tmy_add_domain_initializer_entry(const char *domainname,
+                                           const char *program,
+                                           const u8 is_not,
+                                           const u8 is_delete)
+{
+       struct domain_initializer_entry *new_entry;
+       struct domain_initializer_entry *ptr;
+       static DEFINE_MUTEX(mutex);
+       const struct path_info *saved_program;
+       const struct path_info *saved_domainname = NULL;
+       int error = -ENOMEM;
+       u8 is_last_name = 0;
+
+       if (!tmy_correct_path(program, 1, -1, -1, __FUNCTION__))
+               return -EINVAL; /* No patterns allowed. */
+
+       if (domainname) {
+               if (!tmy_is_domain_def(domainname) &&
+                   tmy_correct_path(domainname, 1, -1, -1, __FUNCTION__))
+                       is_last_name = 1;
+
+               else if (!tmy_is_correct_domain(domainname, __FUNCTION__))
+                       return -EINVAL;
+
+               saved_domainname = tmy_save_name(domainname);
+               if (!saved_domainname)
+                       return -ENOMEM;
+       }
+
+       saved_program = tmy_save_name(program);
+       if (!saved_program)
+               return -ENOMEM;
+
+       mutex_lock(&mutex);
+
+       rcu_read_lock();
+       list_for_each_entry_rcu(ptr, &domain_initializer_list, list) {
+               if (ptr->is_not != is_not ||
+                   ptr->domainname != saved_domainname ||
+                   ptr->program != saved_program)
+                       continue;
+               ptr->is_deleted = is_delete;
+               error = 0;
+               break;
+       }
+       rcu_read_unlock();
+       if (!error)
+               goto out;
+
+       if (is_delete) {
+               error = -ENOENT;
+               goto out;
+       }
+
+       new_entry = tmy_alloc_element(sizeof(*new_entry));
+       if (!new_entry)
+               goto out;
+
+       new_entry->domainname = saved_domainname;
+       new_entry->program = saved_program;
+       new_entry->is_not = is_not;
+       new_entry->is_last_name = is_last_name;
+
+       mb(); /* Avoid out-of-order execution. */
+       /* RCU: Protected by mutex. */
+       list_add_tail_rcu(&new_entry->list, &domain_initializer_list);
+       error = 0;
+out: ;
+       mutex_unlock(&mutex);
+       return error;
+}
+
+/**
+ * tmy_read_domain_initializer_policy - read domain initializer policy.
+ * @head: pointer to "struct io_buffer".
+ *
+ * Returns nonzero if reading incomplete.
+ * Returns zero otherwise.
+ */
+int tmy_read_domain_initializer_policy(struct io_buffer *head)
+{
+       struct list_head *pos;
+       int error = -ENOMEM;
+
+       rcu_read_lock();
+       pos = head->read_var2;
+       if (!pos)
+               pos = &domain_initializer_list;
+       list_for_each_continue_rcu(pos, &domain_initializer_list) {
+               struct domain_initializer_entry *ptr;
+               ptr = list_entry(pos, struct domain_initializer_entry, list);
+               head->read_var2 = pos->prev;
+               if (ptr->is_deleted)
+                       continue;
+               if (ptr->domainname) {
+                       if (tmy_io_printf(head, "%s" TMY_INITIALIZE_DOMAIN
+                                         "%s from %s\n",
+                                         ptr->is_not ? "no_" : "",
+                                         ptr->program->name,
+                                         ptr->domainname->name))
+                               goto out;
+               } else {
+                       if (tmy_io_printf(head, "%s" TMY_INITIALIZE_DOMAIN
+                                         "%s\n",
+                                         ptr->is_not ? "no_" : "",
+                                         ptr->program->name))
+                               goto out;
+               }
+       }
+       error = 0;
+out: ;
+       rcu_read_unlock();
+       return error;
+}
+
+/**
+ * tmy_add_domain_initializer_policy - add domain initializer policy
+ * @data:      a line to parse.
+ * @is_not:    is this overriding?
+ * @is_delete: is this remove request?
+ *
+ * Returns zero on success.
+ * Returns nonzero on failure.
+ *
+ * This function adds or removes a domain initializer entry.
+ */
+int tmy_add_domain_initializer_policy(char *data,
+                                     const u8 is_not,
+                                     const u8 is_delete)
+{
+       char *cp = strstr(data, " from ");
+
+       if (cp) {
+               *cp = '\0';
+               return tmy_add_domain_initializer_entry(cp + 6, data, is_not,
+                                                       is_delete);
+       }
+
+       return tmy_add_domain_initializer_entry(NULL, data, is_not, is_delete);
+}
+
+/* Should I transit to a domain under "<kernel>" domain? */
+static int tmy_is_domain_initializer(const struct path_info *domainname,
+                                    const struct path_info *program,
+                                    const struct path_info *last_name)
+{
+       struct domain_initializer_entry *ptr;
+       int flag = 0;
+
+       rcu_read_lock();
+       list_for_each_entry_rcu(ptr, &domain_initializer_list, list) {
+               if (ptr->is_deleted)
+                       continue;
+
+               if (ptr->domainname) {
+                       if (!ptr->is_last_name) {
+                               if (ptr->domainname != domainname)
+                                       continue;
+                       } else {
+                               if (tmy_pathcmp(ptr->domainname, last_name))
+                                       continue;
+                       }
+               }
+
+               if (tmy_pathcmp(ptr->program, program))
+                       continue;
+               if (ptr->is_not) {
+                       flag = 0;
+                       break;
+               }
+               flag = 1;
+       }
+       rcu_read_unlock();
+       return flag;
+}
+
+/*************************  DOMAIN KEEPER HANDLER  *************************/
+
+static LIST_HEAD(domain_keeper_list);
+
+/* Update domain keeper list. */
+static int tmy_add_domain_keeper_entry(const char *domainname,
+                                      const char *program,
+                                      const u8 is_not,
+                                      const u8 is_delete)
+{
+       struct domain_keeper_entry *new_entry;
+       struct domain_keeper_entry *ptr;
+       const struct path_info *saved_domainname;
+       const struct path_info *saved_program = NULL;
+       static DEFINE_MUTEX(mutex);
+       int error = -ENOMEM;
+       u8 is_last_name = 0;
+
+       if (!tmy_is_domain_def(domainname) &&
+           tmy_correct_path(domainname, 1, -1, -1, __FUNCTION__))
+               is_last_name = 1;
+
+       else if (!tmy_is_correct_domain(domainname, __FUNCTION__))
+               return -EINVAL;
+
+       if (program) {
+               if (!tmy_correct_path(program, 1, -1, -1, __FUNCTION__))
+                       return -EINVAL;
+
+               saved_program = tmy_save_name(program);
+               if (!saved_program)
+                       return -ENOMEM;
+       }
+
+       saved_domainname = tmy_save_name(domainname);
+       if (!saved_domainname)
+               return -ENOMEM;
+
+       mutex_lock(&mutex);
+       rcu_read_lock();
+       list_for_each_entry_rcu(ptr, &domain_keeper_list, list) {
+               if (ptr->is_not != is_not ||
+                   ptr->domainname != saved_domainname ||
+                   ptr->program != saved_program)
+                       continue;
+               ptr->is_deleted = is_delete;
+               error = 0;
+               break;
+       }
+       rcu_read_unlock();
+       if (!error)
+               goto out;
+
+       if (is_delete) {
+               error = -ENOENT;
+               goto out;
+       }
+
+       new_entry = tmy_alloc_element(sizeof(*new_entry));
+       if (!new_entry)
+               goto out;
+
+       new_entry->domainname = saved_domainname;
+       new_entry->program = saved_program;
+       new_entry->is_not = is_not;
+       new_entry->is_last_name = is_last_name;
+       mb(); /* Avoid out-of-order execution. */
+       /* RCU: Protected by mutex. */
+       list_add_tail_rcu(&new_entry->list, &domain_keeper_list);
+       error = 0;
+out: ;
+       mutex_unlock(&mutex);
+       return error;
+}
+
+/**
+ * tmy_add_domain_keeper_policy - add domain keeper policy.
+ * @data:      a line to parse.
+ * @is_not:    is this overriding?
+ * @is_delete: is this remove request?
+ *
+ * Returns zero on success.
+ * Returns nonzero on failure.
+ *
+ * This function adds or removes a domain keeper entry.
+ *
+ */
+int tmy_add_domain_keeper_policy(char *data,
+                                const u8 is_not,
+                                const u8 is_delete)
+{
+       char *cp = strstr(data, " from ");
+
+       if (cp) {
+               *cp = '\0';
+               return tmy_add_domain_keeper_entry(cp + 6, data,
+                                                  is_not, is_delete);
+       }
+
+       return tmy_add_domain_keeper_entry(data, NULL, is_not, is_delete);
+}
+
+/**
+ * tmy_read_domain_keeper_policy - read domain keeper policy.
+ * @head: pointer to "struct io_buffer".
+ *
+ * Returns nonzero if reading incomplete.
+ * Returns zero otherwise.
+ */
+int tmy_read_domain_keeper_policy(struct io_buffer *head)
+{
+       struct list_head *pos;
+       int error = -ENOMEM;
+
+       rcu_read_lock();
+       pos = head->read_var2;
+       if (!pos)
+               pos = &domain_keeper_list;
+       list_for_each_continue_rcu(pos, &domain_keeper_list) {
+               struct domain_keeper_entry *ptr;
+               ptr = list_entry(pos, struct domain_keeper_entry, list);
+               head->read_var2 = pos->prev;
+               if (ptr->is_deleted)
+                       continue;
+               if (ptr->program) {
+                       if (tmy_io_printf(head,
+                                         "%s" TMY_KEEP_DOMAIN
+                                         "%s from %s\n",
+                                         ptr->is_not ? "no_" : "",
+                                         ptr->program->name,
+                                         ptr->domainname->name))
+                               goto out;
+               } else {
+                       if (tmy_io_printf(head,
+                                         "%s" TMY_KEEP_DOMAIN
+                                         "%s\n",
+                                         ptr->is_not ? "no_" : "",
+                                         ptr->domainname->name))
+                               goto out;
+               }
+       }
+       error = 0;
+out: ;
+       rcu_read_unlock();
+       return error;
+}
+
+/* Should I remain in current domain? */
+static int tmy_is_domain_keeper(const struct path_info *domainname,
+                               const struct path_info *program,
+                               const struct path_info *last_name)
+{
+       struct domain_keeper_entry *ptr;
+       int flag = 0;
+
+       rcu_read_lock();
+       list_for_each_entry_rcu(ptr, &domain_keeper_list, list) {
+               if (ptr->is_deleted)
+                       continue;
+               if (!ptr->is_last_name) {
+                       if (ptr->domainname != domainname)
+                               continue;
+               } else {
+                       if (tmy_pathcmp(ptr->domainname, last_name))
+                               continue;
+               }
+               if (ptr->program && tmy_pathcmp(ptr->program, program))
+                       continue;
+               if (ptr->is_not) {
+                       flag = 0;
+                       break;
+               }
+               flag = 1;
+       }
+       rcu_read_unlock();
+       return flag;
+}
+
+/*********************  SYMBOLIC LINKED PROGRAM HANDLER  *********************/
+
+static LIST_HEAD(alias_list);
+
+/* Update alias list. */
+static int tmy_add_alias_entry(const char *original_name,
+                              const char *aliased_name,
+                              const u8 is_delete)
+{
+       struct alias_entry *new_entry;
+       struct alias_entry *ptr;
+       static DEFINE_MUTEX(mutex);
+       const struct path_info *saved_original_name;
+       const struct path_info *saved_aliased_name;
+       int error = -ENOMEM;
+
+       if (!tmy_correct_path(original_name, 1, -1, -1, __FUNCTION__) ||
+           !tmy_correct_path(aliased_name, 1, -1, -1, __FUNCTION__))
+               return -EINVAL; /* No patterns allowed. */
+
+       saved_original_name = tmy_save_name(original_name);
+       saved_aliased_name = tmy_save_name(aliased_name);
+       if (!saved_original_name || !saved_aliased_name)
+               return -ENOMEM;
+
+       mutex_lock(&mutex);
+
+       rcu_read_lock();
+       list_for_each_entry_rcu(ptr, &alias_list, list) {
+               if (ptr->original_name != saved_original_name ||
+                   ptr->aliased_name != saved_aliased_name)
+                       continue;
+               ptr->is_deleted = is_delete;
+               error = 0;
+               break;
+       }
+       rcu_read_unlock();
+       if (!error)
+               goto out;
+
+       if (is_delete) {
+               error = -ENOENT;
+               goto out;
+       }
+
+       new_entry = tmy_alloc_element(sizeof(*new_entry));
+       if (!new_entry)
+               goto out;
+
+       new_entry->original_name = saved_original_name;
+       new_entry->aliased_name = saved_aliased_name;
+
+       mb(); /* Avoid out-of-order execution. */
+       /* RCU: Protected by mutex. */
+       list_add_tail_rcu(&new_entry->list, &alias_list);
+       error = 0;
+out: ;
+       mutex_unlock(&mutex);
+       return error;
+}
+
+/**
+ * tmy_read_alias_policy - read alias policy.
+ * @head: pointer to "struct io_buffer".
+ *
+ * Returns nonzero if reading incomplete.
+ * Returns zero otherwise.
+ */
+int tmy_read_alias_policy(struct io_buffer *head)
+{
+       struct list_head *pos;
+       int error = -ENOMEM;
+
+       rcu_read_lock();
+       pos = head->read_var2;
+       if (!pos)
+               pos = &alias_list;
+       list_for_each_continue_rcu(pos, &alias_list) {
+               struct alias_entry *ptr;
+               ptr = list_entry(pos, struct alias_entry, list);
+               head->read_var2 = pos->prev;
+               if (ptr->is_deleted)
+                       continue;
+               if (tmy_io_printf(head,
+                                 TMY_ALIAS "%s %s\n",
+                                 ptr->original_name->name,
+                                 ptr->aliased_name->name))
+                       goto out;
+       }
+       error = 0;
+out: ;
+       rcu_read_unlock();
+       return error;
+}
+
+/**
+ * tmy_add_alias_policy - add alias policy.
+ * @data:      a line to parse.
+ * @is_delete: is this remove request?
+ *
+ * Returns zero on success.
+ * Returns nonzero on failure.
+ *
+ * This function adds or removes an alias entry.
+ */
+int tmy_add_alias_policy(char *data, const u8 is_delete)
+{
+       char *cp = strchr(data, ' ');
+
+       if (!cp)
+               return -EINVAL;
+       *cp++ = '\0';
+
+       return tmy_add_alias_entry(data, cp, is_delete);
+}
+
+/************************  DOMAIN AGGREGATOR HANDLER  ************************/
+
+static LIST_HEAD(aggregator_list);
+
+/* Update aggregator list. */
+static int tmy_add_aggregator_entry(const char *original_name,
+                                   const char *aggregated_name,
+                                   const u8 is_delete)
+{
+       struct aggregator_entry *new_entry;
+       struct aggregator_entry *ptr;
+       static DEFINE_MUTEX(mutex);
+       const struct path_info *saved_original_name;
+       const struct path_info *saved_aggregated_name;
+       int error = -ENOMEM;
+
+       if (!tmy_correct_path(original_name, 1, 0, -1, __FUNCTION__) ||
+           !tmy_correct_path(aggregated_name, 1, -1, -1, __FUNCTION__))
+               return -EINVAL;
+
+       saved_original_name = tmy_save_name(original_name);
+       saved_aggregated_name = tmy_save_name(aggregated_name);
+       if (!saved_original_name || !saved_aggregated_name)
+               return -ENOMEM;
+
+       mutex_lock(&mutex);
+
+       rcu_read_lock();
+       list_for_each_entry_rcu(ptr, &aggregator_list, list) {
+               if (ptr->original_name != saved_original_name ||
+                   ptr->aggregated_name != saved_aggregated_name)
+                       continue;
+               ptr->is_deleted = is_delete;
+               error = 0;
+               break;
+       }
+       rcu_read_unlock();
+       if (!error)
+               goto out;
+
+       if (is_delete) {
+               error = -ENOENT;
+               goto out;
+       }
+
+       new_entry = tmy_alloc_element(sizeof(*new_entry));
+       if (!new_entry)
+               goto out;
+
+       new_entry->original_name = saved_original_name;
+       new_entry->aggregated_name = saved_aggregated_name;
+
+       mb(); /* Avoid out-of-order execution. */
+       /* RCU: Protected by mutex. */
+       list_add_tail_rcu(&new_entry->list, &aggregator_list);
+       error = 0;
+out: ;
+       mutex_unlock(&mutex);
+       return error;
+}
+
+/**
+ * tmy_read_aggregator_policy - read aggregator policy.
+ * @head: pointer to "struct io_buffer".
+ *
+ * Returns nonzero if reading incomplete.
+ * Returns zero otherwise.
+ */
+int tmy_read_aggregator_policy(struct io_buffer *head)
+{
+       struct list_head *pos;
+       int error = -ENOMEM;
+
+       rcu_read_lock();
+       pos = head->read_var2;
+       if (!pos)
+               pos = &aggregator_list;
+       list_for_each_continue_rcu(pos, &aggregator_list) {
+               struct aggregator_entry *ptr;
+               ptr = list_entry(pos, struct aggregator_entry, list);
+               head->read_var2 = pos->prev;
+               if (ptr->is_deleted)
+                       continue;
+               if (tmy_io_printf(head,
+                                 TMY_AGGREGATOR "%s %s\n",
+                                 ptr->original_name->name,
+                                 ptr->aggregated_name->name))
+                       goto out;
+       }
+       error = 0;
+out: ;
+       rcu_read_unlock();
+       return error;
+}
+
+/**
+ * tmy_add_aggregator_policy - add aggregator policy.
+ * @data:      a line to parse.
+ * @is_delete: is this remove request?
+ *
+ * Returns zero on success.
+ * Returns nonzero on failure.
+ *
+ * This function adds or removes an aggregator entry.
+ */
+int tmy_add_aggregator_policy(char *data, const u8 is_delete)
+{
+       char *cp = strchr(data, ' ');
+
+       if (!cp)
+               return -EINVAL;
+       *cp++ = '\0';
+
+       return tmy_add_aggregator_entry(data, cp, is_delete);
+}
+
+/*************************  DOMAIN DELETION HANDLER  *************************/
+
+/**
+ * tmy_delete_domain - delete a domain.
+ * @domainname0: domainname to delete.
+ *
+ * Returns zero.
+ *
+ * This function deletes domains.
+ * The behavior of deleting domain is like deleting files on Linux's
+ * filesystem. A process transits to different domain upon do_execve(),
+ * and the process can refer the deleted domains after the domain is deleted,
+ * like a process opens a file and the process can read()/write() the deleted
+ * file after the file is deleted.
+ * This avoids processes from crashing due to referring non-existent domains.
+ * Administrator manually terminates processes thet are referring deleted
+ * domains after deleting domains.
+ * Also, undeleting domains is supported. See tmy_undelete_domain().
+ */
+int tmy_delete_domain(char *domainname0)
+{
+       struct domain_info *domain;
+       struct domain_info *domain2;
+       struct path_info domainname;
+
+       domainname.name = domainname0;
+       tmy_fill_path_info(&domainname);
+
+       mutex_lock(&new_domain_assign_lock);
+       /* Is there an active domain? */
+       rcu_read_lock();
+       list_for_each_entry_rcu(domain, &domain_list, list) {
+               /* Never delete KERNEL_DOMAIN */
+               if (domain == &KERNEL_DOMAIN || domain->is_deleted ||
+                   tmy_pathcmp(domain->domainname, &domainname))
+                       continue;
+               /* Mark already deleted domains as non undeletable. */
+               list_for_each_entry_rcu(domain2, &domain_list, list) {
+                       if (!domain2->is_deleted ||
+                           tmy_pathcmp(domain2->domainname, &domainname))
+                               continue;
+                       domain2->is_deleted = 255;
+               }
+               /* Delete and mark active domain as undeletable. */
+               domain->is_deleted = 1;
+               break;
+       }
+       rcu_read_unlock();
+       mutex_unlock(&new_domain_assign_lock);
+
+       return 0;
+}
+
+/**
+ * tmy_undelete_domain - undelete a domain.
+ * @domainname0: domainname to undelete.
+ *
+ * Returns pointer to undeleted "struct domain_info" on success.
+ * Returns NULL on failure.
+ *
+ * This function undeletes domains.
+ * Not only the domain previously deleted by tmy_delete_domain()
+ * but also all domains deleted by tmy_delete_domain() are undeletable.
+ * If there is no deleted domain named @domainname0 or
+ * a not-yet-deleted domain named @domainname0 exists, undelete fails.
+ * Otherwise, previously deleted domain named @domainname0 is undeleted.
+ */
+struct domain_info *tmy_undelete_domain(const char *domainname0)
+{
+       struct domain_info *domain;
+       struct domain_info *candidate_domain = NULL;
+       struct path_info domainname;
+
+       domainname.name = domainname0;
+       tmy_fill_path_info(&domainname);
+
+       mutex_lock(&new_domain_assign_lock);
+
+       rcu_read_lock();
+       list_for_each_entry_rcu(domain, &domain_list, list) {
+               if (tmy_pathcmp(&domainname, domain->domainname))
+                       continue;
+
+               if (!domain->is_deleted) {
+                       /* This domain is active. I can't undelete. */
+                       candidate_domain = NULL;
+                       break;
+               }
+
+               /* Is this domain undeletable? */
+               if (domain->is_deleted == 1)
+                       candidate_domain = domain;
+       }
+       if (candidate_domain)
+               candidate_domain->is_deleted = 0;
+       rcu_read_unlock();
+       mutex_unlock(&new_domain_assign_lock);
+
+       return candidate_domain;
+}
+
+/************************  DOMAIN TRANSITION HANDLER  ************************/
+
+/**
+ * tmy_find_domain - find a domain with given domainname.
+ * @domainname0: the domainname to find.
+ *
+ * Returns pointer to "struct domain_info" on success.
+ * Returns NULL on failure.
+ *
+ * This function does not create a new domain
+ * if a domain named @domainname0 does not exist.
+ */
+struct domain_info *tmy_find_domain(const char *domainname0)
+{
+       struct domain_info *domain;
+       struct domain_info *found = NULL;
+       struct path_info domainname;
+
+       domainname.name = domainname0;
+       tmy_fill_path_info(&domainname);
+
+       rcu_read_lock();
+       list_for_each_entry_rcu(domain, &domain_list, list) {
+               if (domain->is_deleted ||
+                   tmy_pathcmp(&domainname, domain->domainname))
+                       continue;
+               found = domain;
+               break;
+       }
+       rcu_read_unlock();
+       return found;
+}
+
+/**
+ * tmy_new_domain - find or assign a domain with given domainname.
+ * @domainname: the domainname to find.
+ * @profile:    profile number to assign if newly created.
+ *
+ * Returns pointer to "struct domain_info" on success.
+ * Returns NULL on failure.
+ *
+ * This function creates a new domain if a domain named @domainname0
+ * does not exist.
+ */
+struct domain_info *tmy_new_domain(const char *domainname,
+                                  const u8 profile)
+{
+       struct domain_info *domain = NULL;
+       const struct path_info *saved_domainname;
+       int error = -ENOMEM;
+
+       mutex_lock(&new_domain_assign_lock);
+
+       domain = tmy_find_domain(domainname);
+       if (domain)
+               goto out;
+
+       if (!tmy_is_correct_domain(domainname, __FUNCTION__))
+               goto out;
+
+       saved_domainname = tmy_save_name(domainname);
+       if (!saved_domainname)
+               goto out;
+
+       /* Can I reuse memory of deleted domain? */
+       rcu_read_lock();
+       list_for_each_entry_rcu(domain, &domain_list, list) {
+               struct task_struct *p;
+               struct acl_info *ptr;
+               int flag;
+
+               if (!domain->is_deleted ||
+                   domain->domainname != saved_domainname)
+                       continue;
+               flag = 0;
+
+               /***** CRITICAL SECTION START *****/
+               read_lock(&tasklist_lock);
+               for_each_process(p) {
+                       /* "struct task_struct"->security is not NULL. */
+                       if (((struct tmy_security *) p->security)->domain
+                           == domain) {
+                               flag = 1;
+                               break;
+                       }
+               }
+               read_unlock(&tasklist_lock);
+               /***** CRITICAL SECTION END *****/
+
+               /* Somebody is still referring this deleted domain. */
+               if (flag)
+                       continue;
+
+               /* OK. Let's reuse memory for this deleted domain. */
+
+               /* Delete all entries in this deleted domain. */
+               list_for_each_entry_rcu(ptr, &domain->acl_info_list, list)
+                       ptr->is_deleted = 1;
+
+               domain->profile = profile;
+               domain->quota_warned = 0;
+
+               mb(); /* Avoid out-of-order execution. */
+               /* Undelete this deleted domain. */
+               domain->is_deleted = 0;
+               error = 0;
+               break;
+       }
+       rcu_read_unlock();
+       if (!error)
+               goto out;
+
+       /* No memory reusable. Create using new memory. */
+       domain = tmy_alloc_element(sizeof(*domain));
+       if (!domain)
+               goto out;
+
+       INIT_LIST_HEAD(&domain->list);
+       INIT_LIST_HEAD(&domain->acl_info_list);
+       domain->domainname = saved_domainname;
+       domain->profile = profile;
+       mb(); /* Avoid out-of-order execution. */
+       /* RCU: Protected by new_domain_assign_lock. */
+       list_add_tail_rcu(&domain->list, &domain_list);
+out: ;
+       mutex_unlock(&new_domain_assign_lock);
+
+       return domain;
+}
+
+/* Convert non ASCII printable characters to ASCII printable characters. */
+static int tmy_escape(char *dest, const char *src, int dest_len)
+{
+       while (*src) {
+               const unsigned char c = *(const unsigned char *) src;
+
+               if (c == '\\') {
+                       dest_len -= 2;
+                       if (dest_len <= 0)
+                               goto out;
+                       *dest++ = '\\';
+                       *dest++ = '\\';
+               } else if (c > ' ' && c < 127) {
+                       if (--dest_len <= 0)
+                               goto out;
+                       *dest++ = c;
+               } else {
+                       dest_len -= 4;
+                       if (dest_len <= 0)
+                               goto out;
+                       *dest++ = '\\';
+                       *dest++ = (c >> 6) + '0';
+                       *dest++ = ((c >> 3) & 7) + '0';
+                       *dest++ = (c & 7) + '0';
+               }
+               src++;
+       }
+
+       if (--dest_len <= 0)
+               goto out;
+       *dest = '\0';
+
+       return 0;
+out: ;
+       return -ENOMEM;
+}
+
+/* Get argv[0] of "struct linux_binprm". */
+static char *tmy_get_argv0(struct linux_binprm *bprm)
+{
+       char *arg_ptr;
+       int arg_len = 0;
+       unsigned long pos = bprm->p;
+       int i = pos / PAGE_SIZE;
+       int offset = pos % PAGE_SIZE;
+
+       if (bprm->argc <= 0)
+               return NULL;
+
+       arg_ptr = tmy_alloc(PAGE_SIZE);
+
+       if (!arg_ptr)
+               goto out;
+
+       while (1) {
+               struct page *page;
+               const char *kaddr;
+               char *tmp_arg;
+
+#ifdef CONFIG_MMU
+               if (get_user_pages(current, bprm->mm, pos,
+                                  1, 0, 1, &page, NULL) <= 0)
+                       goto out;
+#else
+               page = bprm->page[i];
+#endif
+               kaddr = kmap(page);
+               if (!kaddr) { /* Mapping failed. */
+#ifdef CONFIG_MMU
+                       put_page(page);
+#endif
+                       goto out;
+               }
+
+               memmove(arg_ptr + arg_len, kaddr + offset, PAGE_SIZE - offset);
+               kunmap(page);
+
+#ifdef CONFIG_MMU
+               put_page(page);
+               pos += PAGE_SIZE - offset;
+#endif
+
+               arg_len += PAGE_SIZE - offset;
+
+               if (memchr(arg_ptr, '\0', arg_len))
+                       break;
+
+               tmp_arg = tmy_alloc(arg_len + PAGE_SIZE);
+               if (!tmp_arg)
+                       goto out;
+
+               memmove(tmp_arg, arg_ptr, arg_len);
+               tmy_free(arg_ptr);
+               arg_ptr = tmp_arg;
+               i++;
+               offset = 0;
+       }
+       return arg_ptr;
+out: ;
+       tmy_free(arg_ptr);
+
+       return NULL;
+}
+
+/**
+ * tmy_find_next_domain - find a domain to transit to if do_execve() succeeds.
+ * @bprm:        pointer to "struct linux_binprm".
+ * @next_domain: pointer to pointer to "struct domain_info".
+ *
+ * Returns zero if success. @next_domain receives new domain to transit to.
+ * Returns nonzero on failure.
+ *
+ * This function handles TOMOYO Linux's domain transition.
+ * New domains are automatically created unless the domain the caller process
+ * belongs to is assigned a profile for enforcing mode.
+ */
+int tmy_find_next_domain(struct linux_binprm *bprm,
+                        struct domain_info **next_domain)
+{
+       /* This function assumes that the size of buffer returned */
+       /* by tmy_realpath() = TMY_MAX_PATHNAME_LEN. */
+       struct domain_info *old_domain = TMY_SECURITY->domain;
+       struct domain_info *domain = NULL;
+       const char *old_domain_name = old_domain->domainname->name;
+       const char *original_name = bprm->filename;
+       struct file *filp = bprm->file;
+       char *new_domain_name = NULL;
+       char *real_program_name = NULL;
+       char *symlink_program_name = NULL;
+       const u8 is_enforce = tmy_enforce(TMY_MAC_FOR_FILE);
+       int retval;
+       struct path_info r;
+       struct path_info s;
+       struct path_info l;
+
+       /*
+        * Built-in initializers.
+        * This is needed because policies are not loaded
+        * until starting /sbin/init .
+        */
+       static int first = 1;
+       if (first) {
+               tmy_add_domain_initializer_entry(NULL, "/sbin/hotplug", 0, 0);
+               tmy_add_domain_initializer_entry(NULL, "/sbin/modprobe", 0, 0);
+               tmy_add_domain_initializer_entry(NULL, "/sbin/udevd", 0, 0);
+               first = 0;
+       }
+
+       /* Get realpath of program. */
+       /* I hope tmy_realpath() won't fail with -ENOMEM. */
+       retval = -ENOENT;
+       real_program_name = tmy_realpath(original_name);
+
+       if (!real_program_name)
+               goto out;
+
+       /* Get realpath of symbolic link. */
+       symlink_program_name = tmy_realpath_nofollow(original_name);
+       if (!symlink_program_name)
+               goto out;
+
+       r.name = real_program_name;
+       tmy_fill_path_info(&r);
+       s.name = symlink_program_name;
+       tmy_fill_path_info(&s);
+       l.name = strrchr(old_domain_name, ' ');
+
+       if (l.name)
+               l.name++;
+       else
+               l.name = old_domain_name;
+       tmy_fill_path_info(&l);
+
+       /* Check 'alias' directive. */
+       if (tmy_pathcmp(&r, &s)) {
+               struct alias_entry *ptr;
+
+               /* Is this program allowed to be called via symbolic links? */
+               rcu_read_lock();
+               list_for_each_entry_rcu(ptr, &alias_list, list) {
+                       if (ptr->is_deleted ||
+                           tmy_pathcmp(&r, ptr->original_name) ||
+                           tmy_pathcmp(&s, ptr->aliased_name))
+                               continue;
+                       memset(real_program_name, 0, TMY_MAX_PATHNAME_LEN);
+                       strncpy(real_program_name,
+                               ptr->aliased_name->name,
+                               TMY_MAX_PATHNAME_LEN - 1);
+                       tmy_fill_path_info(&r);
+                       break;
+               }
+               rcu_read_unlock();
+       }
+
+       /* Compare basename of real_program_name and argv[0] */
+       if (bprm->argc > 0 && tmy_flags(TMY_MAC_FOR_ARGV0)) {
+
+               char *org_argv0 = tmy_get_argv0(bprm);
+
+               retval = -ENOMEM;
+               if (org_argv0) {
+
+                       const int len = strlen(org_argv0);
+                       char *printable_argv0 = tmy_alloc(len * 4 + 8);
+
+                       if (printable_argv0 &&
+                           !tmy_escape(printable_argv0, org_argv0,
+                                       len * 4 + 8)) {
+                               const char *base_argv0;
+                               const char *base_filename;
+
+                               base_argv0 = strrchr(printable_argv0, '/');
+                               if (!base_argv0)
+                                       base_argv0 = printable_argv0;
+                               else
+                                       base_argv0++;
+
+                               base_filename = strrchr(real_program_name, '/');
+                               if (!base_filename)
+                                       base_filename = real_program_name;
+                               else
+                                       base_filename++;
+
+                               if (strcmp(base_argv0, base_filename))
+                                       retval = tmy_argv0_perm(&r, base_argv0);
+                               else
+                                       retval = 0;
+                       }
+
+                       tmy_free(printable_argv0);
+                       tmy_free(org_argv0);
+               }
+
+               if (retval)
+                       goto out;
+
+       }
+
+
+       /* Check 'aggregator' directive. */
+       {
+               struct aggregator_entry *ptr;
+
+               /* Is this program allowed to be aggregated? */
+               rcu_read_lock();
+               list_for_each_entry_rcu(ptr, &aggregator_list, list) {
+                       if (ptr->is_deleted ||
+                           !tmy_path_match(&r, ptr->original_name))
+                               continue;
+                       memset(real_program_name, 0, TMY_MAX_PATHNAME_LEN);
+                       strncpy(real_program_name,
+                               ptr->aggregated_name->name,
+                               TMY_MAX_PATHNAME_LEN - 1);
+                       tmy_fill_path_info(&r);
+                       break;
+               }
+               rcu_read_unlock();
+       }
+
+       /* Check execute permission. */
+       retval = tmy_exec_perm(&r, filp);
+       if (retval < 0)
+               goto out;
+
+       /* Allocate memory for calcurating domain name. */
+       retval = -ENOMEM;
+       new_domain_name = tmy_alloc(TMY_MAX_PATHNAME_LEN + 16);
+       if (!new_domain_name)
+               goto out;
+
+       if (tmy_is_domain_initializer(old_domain->domainname, &r, &l))
+               /* Transit to the child of KERNEL_DOMAIN domain. */
+               snprintf(new_domain_name, TMY_MAX_PATHNAME_LEN + 1,
+                        TMY_ROOT_NAME " " "%s", real_program_name);
+       else if (old_domain == &KERNEL_DOMAIN && !sbin_init_started)
+               /*
+                * Needn't to transit from kernel domain
+                * before starting /sbin/init .
+                * But transit from kernel domain if executing initializers,
+                * for they might start before /sbin/init .
+                */
+               domain = old_domain;
+       else if (tmy_is_domain_keeper(old_domain->domainname, &r, &l))
+               /* Keep current domain. */
+               domain = old_domain;
+       else
+               /* Normal domain transition. */
+               snprintf(new_domain_name,
+                        TMY_MAX_PATHNAME_LEN + 1,
+                        "%s %s",
+                        old_domain_name,
+                        real_program_name);
+
+       if (domain || strlen(new_domain_name) >= TMY_MAX_PATHNAME_LEN)
+               goto ok;
+
+       if (is_enforce) {
+               domain = tmy_find_domain(new_domain_name);
+               if (!domain &&
+                   tmy_supervisor("#Need to create domain\n%s\n",
+                                  new_domain_name) == 0) {
+                       const u8 profile = TMY_SECURITY->domain->profile;
+                       domain = tmy_new_domain(new_domain_name, profile);
+               }
+       } else {
+               const u8 profile = TMY_SECURITY->domain->profile;
+               domain = tmy_new_domain(new_domain_name, profile);
+       }
+
+ok: ;
+
+       if (!domain) {
+               printk(KERN_INFO "TOMOYO-ERROR: Domain '%s' not defined.\n",
+                      new_domain_name);
+               if (is_enforce)
+                       retval = -EPERM;
+       } else
+               retval = 0;
+out: ;
+
+       tmy_free(new_domain_name);
+       tmy_free(real_program_name);
+       tmy_free(symlink_program_name);
+       *next_domain = domain ? domain : old_domain;
+
+       return retval;
+}

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