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    SubjectRe: [PATCH] TOMOYO: Use RCU primitives for list operation
    Quoting Tetsuo Handa (penguin-kernel@I-love.SAKURA.ne.jp):
    > Can somebody please review?

    Thanks, Tetsuo!

    Just out of curiosity (and bc I'm personally much more familiar with plain old
    rcu), I assume you have a list of places where sleeping under rcu is necessary
    or greatly simplifies/cleans up the code?

    Acked-by: Serge Hallyn <serue@us.ibm.com>

    -serge

    > ----------
    > [PATCH] TOMOYO: Use RCU primitives for list operation
    >
    > Currently, TOMOYO is using down_read() only for protecting ->prev member from
    > writers. If we convert list operation using RCU primitives so that readers don't
    > look at ->prev member, we can replace down_read() by srcu_read_lock().
    >
    > tomoyo_read_lock()/tomoyo_read_unlock() (these are wrappers for
    > srcu_read_lock()/srcu_read_unlock()) protects the data against the garbage
    > collector (which will be added in the future). I call tomoyo_read_lock() when
    > /sys/kernel/security/tomoyo/ interface is open()ed and call
    > tomoyo_read_unlock() when /sys/kernel/security/tomoyo/ interface is close()d
    > rather than calling tomoyo_read_lock()/tomoyo_read_unlock() upon individual
    > read()/write() requests. In this way, the pointers saved in
    > "struct tomoyo_io_buffer" are guaranteed to be valid. Please ignore
    >
    > warning: context imbalance in 'tomoyo_open_control' - wrong count at exit
    > warning: context imbalance in 'tomoyo_close_control' - unexpected unlock
    >
    > messages when built with "C=1" option.
    >
    > Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
    > ---
    > common.c | 90 +++++++++++++++++++++++++++----------------------
    > common.h | 28 +++++++++++----
    > domain.c | 63 ++++++++++++++++++++--------------
    > file.c | 110 ++++++++++++++++++++++++++++++++++++++++++-------------------
    > realpath.c | 8 ++--
    > tomoyo.c | 20 +++++++++--
    > 6 files changed, 207 insertions(+), 112 deletions(-)
    >
    > diff --git a/security/tomoyo/common.c b/security/tomoyo/common.c
    > index 6c60616..f01b936 100644
    > --- a/security/tomoyo/common.c
    > +++ b/security/tomoyo/common.c
    > @@ -365,10 +365,9 @@ bool tomoyo_is_domain_def(const unsigned char *buffer)
    > *
    > * @domainname: The domainname to find.
    > *
    > - * Caller must call down_read(&tomoyo_domain_list_lock); or
    > - * down_write(&tomoyo_domain_list_lock); .
    > - *
    > * Returns pointer to "struct tomoyo_domain_info" if found, NULL otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > struct tomoyo_domain_info *tomoyo_find_domain(const char *domainname)
    > {
    > @@ -377,7 +376,7 @@ struct tomoyo_domain_info *tomoyo_find_domain(const char *domainname)
    >
    > name.name = domainname;
    > tomoyo_fill_path_info(&name);
    > - list_for_each_entry(domain, &tomoyo_domain_list, list) {
    > + list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
    > if (!domain->is_deleted &&
    > !tomoyo_pathcmp(&name, domain->domainname))
    > return domain;
    > @@ -829,6 +828,8 @@ bool tomoyo_verbose_mode(const struct tomoyo_domain_info *domain)
    > * @domain: Pointer to "struct tomoyo_domain_info".
    > *
    > * Returns true if the domain is not exceeded quota, false otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > bool tomoyo_domain_quota_is_ok(struct tomoyo_domain_info * const domain)
    > {
    > @@ -837,8 +838,7 @@ bool tomoyo_domain_quota_is_ok(struct tomoyo_domain_info * const domain)
    >
    > if (!domain)
    > return true;
    > - down_read(&tomoyo_domain_acl_info_list_lock);
    > - list_for_each_entry(ptr, &domain->acl_info_list, list) {
    > + list_for_each_entry_rcu(ptr, &domain->acl_info_list, list) {
    > if (ptr->type & TOMOYO_ACL_DELETED)
    > continue;
    > switch (tomoyo_acl_type2(ptr)) {
    > @@ -866,7 +866,6 @@ bool tomoyo_domain_quota_is_ok(struct tomoyo_domain_info * const domain)
    > break;
    > }
    > }
    > - up_read(&tomoyo_domain_acl_info_list_lock);
    > if (count < tomoyo_check_flags(domain, TOMOYO_MAX_ACCEPT_ENTRY))
    > return true;
    > if (!domain->quota_warned) {
    > @@ -1096,6 +1095,8 @@ static DECLARE_RWSEM(tomoyo_policy_manager_list_lock);
    > * @is_delete: True if it is a delete request.
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_update_manager_entry(const char *manager,
    > const bool is_delete)
    > @@ -1118,7 +1119,7 @@ static int tomoyo_update_manager_entry(const char *manager,
    > if (!saved_manager)
    > return -ENOMEM;
    > down_write(&tomoyo_policy_manager_list_lock);
    > - list_for_each_entry(ptr, &tomoyo_policy_manager_list, list) {
    > + list_for_each_entry_rcu(ptr, &tomoyo_policy_manager_list, list) {
    > if (ptr->manager != saved_manager)
    > continue;
    > ptr->is_deleted = is_delete;
    > @@ -1134,7 +1135,7 @@ static int tomoyo_update_manager_entry(const char *manager,
    > goto out;
    > new_entry->manager = saved_manager;
    > new_entry->is_domain = is_domain;
    > - list_add_tail(&new_entry->list, &tomoyo_policy_manager_list);
    > + list_add_tail_rcu(&new_entry->list, &tomoyo_policy_manager_list);
    > error = 0;
    > out:
    > up_write(&tomoyo_policy_manager_list_lock);
    > @@ -1147,6 +1148,8 @@ static int tomoyo_update_manager_entry(const char *manager,
    > * @head: Pointer to "struct tomoyo_io_buffer".
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_write_manager_policy(struct tomoyo_io_buffer *head)
    > {
    > @@ -1166,6 +1169,8 @@ static int tomoyo_write_manager_policy(struct tomoyo_io_buffer *head)
    > * @head: Pointer to "struct tomoyo_io_buffer".
    > *
    > * Returns 0.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_read_manager_policy(struct tomoyo_io_buffer *head)
    > {
    > @@ -1174,7 +1179,6 @@ static int tomoyo_read_manager_policy(struct tomoyo_io_buffer *head)
    >
    > if (head->read_eof)
    > return 0;
    > - down_read(&tomoyo_policy_manager_list_lock);
    > list_for_each_cookie(pos, head->read_var2,
    > &tomoyo_policy_manager_list) {
    > struct tomoyo_policy_manager_entry *ptr;
    > @@ -1186,7 +1190,6 @@ static int tomoyo_read_manager_policy(struct tomoyo_io_buffer *head)
    > if (!done)
    > break;
    > }
    > - up_read(&tomoyo_policy_manager_list_lock);
    > head->read_eof = done;
    > return 0;
    > }
    > @@ -1196,6 +1199,8 @@ static int tomoyo_read_manager_policy(struct tomoyo_io_buffer *head)
    > *
    > * Returns true if the current process is permitted to modify policy
    > * via /sys/kernel/security/tomoyo/ interface.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static bool tomoyo_is_policy_manager(void)
    > {
    > @@ -1209,29 +1214,25 @@ static bool tomoyo_is_policy_manager(void)
    > return true;
    > if (!tomoyo_manage_by_non_root && (task->cred->uid || task->cred->euid))
    > return false;
    > - down_read(&tomoyo_policy_manager_list_lock);
    > - list_for_each_entry(ptr, &tomoyo_policy_manager_list, list) {
    > + list_for_each_entry_rcu(ptr, &tomoyo_policy_manager_list, list) {
    > if (!ptr->is_deleted && ptr->is_domain
    > && !tomoyo_pathcmp(domainname, ptr->manager)) {
    > found = true;
    > break;
    > }
    > }
    > - up_read(&tomoyo_policy_manager_list_lock);
    > if (found)
    > return true;
    > exe = tomoyo_get_exe();
    > if (!exe)
    > return false;
    > - down_read(&tomoyo_policy_manager_list_lock);
    > - list_for_each_entry(ptr, &tomoyo_policy_manager_list, list) {
    > + list_for_each_entry_rcu(ptr, &tomoyo_policy_manager_list, list) {
    > if (!ptr->is_deleted && !ptr->is_domain
    > && !strcmp(exe, ptr->manager->name)) {
    > found = true;
    > break;
    > }
    > }
    > - up_read(&tomoyo_policy_manager_list_lock);
    > if (!found) { /* Reduce error messages. */
    > static pid_t last_pid;
    > const pid_t pid = current->pid;
    > @@ -1252,6 +1253,8 @@ static bool tomoyo_is_policy_manager(void)
    > * @data: String to parse.
    > *
    > * Returns true on success, false otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static bool tomoyo_is_select_one(struct tomoyo_io_buffer *head,
    > const char *data)
    > @@ -1267,11 +1270,8 @@ static bool tomoyo_is_select_one(struct tomoyo_io_buffer *head,
    > domain = tomoyo_real_domain(p);
    > read_unlock(&tasklist_lock);
    > } else if (!strncmp(data, "domain=", 7)) {
    > - if (tomoyo_is_domain_def(data + 7)) {
    > - down_read(&tomoyo_domain_list_lock);
    > + if (tomoyo_is_domain_def(data + 7))
    > domain = tomoyo_find_domain(data + 7);
    > - up_read(&tomoyo_domain_list_lock);
    > - }
    > } else
    > return false;
    > head->write_var1 = domain;
    > @@ -1285,13 +1285,11 @@ static bool tomoyo_is_select_one(struct tomoyo_io_buffer *head,
    > if (domain) {
    > struct tomoyo_domain_info *d;
    > head->read_var1 = NULL;
    > - down_read(&tomoyo_domain_list_lock);
    > - list_for_each_entry(d, &tomoyo_domain_list, list) {
    > + list_for_each_entry_rcu(d, &tomoyo_domain_list, list) {
    > if (d == domain)
    > break;
    > head->read_var1 = &d->list;
    > }
    > - up_read(&tomoyo_domain_list_lock);
    > head->read_var2 = NULL;
    > head->read_bit = 0;
    > head->read_step = 0;
    > @@ -1307,6 +1305,8 @@ static bool tomoyo_is_select_one(struct tomoyo_io_buffer *head,
    > * @domainname: The name of domain.
    > *
    > * Returns 0.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_delete_domain(char *domainname)
    > {
    > @@ -1317,7 +1317,7 @@ static int tomoyo_delete_domain(char *domainname)
    > tomoyo_fill_path_info(&name);
    > down_write(&tomoyo_domain_list_lock);
    > /* Is there an active domain? */
    > - list_for_each_entry(domain, &tomoyo_domain_list, list) {
    > + list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
    > /* Never delete tomoyo_kernel_domain */
    > if (domain == &tomoyo_kernel_domain)
    > continue;
    > @@ -1337,6 +1337,8 @@ static int tomoyo_delete_domain(char *domainname)
    > * @head: Pointer to "struct tomoyo_io_buffer".
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_write_domain_policy(struct tomoyo_io_buffer *head)
    > {
    > @@ -1359,11 +1361,9 @@ static int tomoyo_write_domain_policy(struct tomoyo_io_buffer *head)
    > domain = NULL;
    > if (is_delete)
    > tomoyo_delete_domain(data);
    > - else if (is_select) {
    > - down_read(&tomoyo_domain_list_lock);
    > + else if (is_select)
    > domain = tomoyo_find_domain(data);
    > - up_read(&tomoyo_domain_list_lock);
    > - } else
    > + else
    > domain = tomoyo_find_or_assign_new_domain(data, 0);
    > head->write_var1 = domain;
    > return 0;
    > @@ -1508,6 +1508,8 @@ static bool tomoyo_print_entry(struct tomoyo_io_buffer *head,
    > * @head: Pointer to "struct tomoyo_io_buffer".
    > *
    > * Returns 0.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_read_domain_policy(struct tomoyo_io_buffer *head)
    > {
    > @@ -1519,7 +1521,6 @@ static int tomoyo_read_domain_policy(struct tomoyo_io_buffer *head)
    > return 0;
    > if (head->read_step == 0)
    > head->read_step = 1;
    > - down_read(&tomoyo_domain_list_lock);
    > list_for_each_cookie(dpos, head->read_var1, &tomoyo_domain_list) {
    > struct tomoyo_domain_info *domain;
    > const char *quota_exceeded = "";
    > @@ -1552,7 +1553,6 @@ acl_loop:
    > if (head->read_step == 3)
    > goto tail_mark;
    > /* Print ACL entries in the domain. */
    > - down_read(&tomoyo_domain_acl_info_list_lock);
    > list_for_each_cookie(apos, head->read_var2,
    > &domain->acl_info_list) {
    > struct tomoyo_acl_info *ptr
    > @@ -1562,7 +1562,6 @@ acl_loop:
    > if (!done)
    > break;
    > }
    > - up_read(&tomoyo_domain_acl_info_list_lock);
    > if (!done)
    > break;
    > head->read_step = 3;
    > @@ -1574,7 +1573,6 @@ tail_mark:
    > if (head->read_single_domain)
    > break;
    > }
    > - up_read(&tomoyo_domain_list_lock);
    > head->read_eof = done;
    > return 0;
    > }
    > @@ -1590,6 +1588,8 @@ tail_mark:
    > *
    > * ( echo "select " $domainname; echo "use_profile " $profile ) |
    > * /usr/lib/ccs/loadpolicy -d
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_write_domain_profile(struct tomoyo_io_buffer *head)
    > {
    > @@ -1601,9 +1601,7 @@ static int tomoyo_write_domain_profile(struct tomoyo_io_buffer *head)
    > if (!cp)
    > return -EINVAL;
    > *cp = '\0';
    > - down_read(&tomoyo_domain_list_lock);
    > domain = tomoyo_find_domain(cp + 1);
    > - up_read(&tomoyo_domain_list_lock);
    > if (strict_strtoul(data, 10, &profile))
    > return -EINVAL;
    > if (domain && profile < TOMOYO_MAX_PROFILES
    > @@ -1625,6 +1623,8 @@ static int tomoyo_write_domain_profile(struct tomoyo_io_buffer *head)
    > * awk ' { if ( domainname == "" ) { if ( $1 == "<kernel>" )
    > * domainname = $0; } else if ( $1 == "use_profile" ) {
    > * print $2 " " domainname; domainname = ""; } } ; '
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_read_domain_profile(struct tomoyo_io_buffer *head)
    > {
    > @@ -1633,7 +1633,6 @@ static int tomoyo_read_domain_profile(struct tomoyo_io_buffer *head)
    >
    > if (head->read_eof)
    > return 0;
    > - down_read(&tomoyo_domain_list_lock);
    > list_for_each_cookie(pos, head->read_var1, &tomoyo_domain_list) {
    > struct tomoyo_domain_info *domain;
    > domain = list_entry(pos, struct tomoyo_domain_info, list);
    > @@ -1644,7 +1643,6 @@ static int tomoyo_read_domain_profile(struct tomoyo_io_buffer *head)
    > if (!done)
    > break;
    > }
    > - up_read(&tomoyo_domain_list_lock);
    > head->read_eof = done;
    > return 0;
    > }
    > @@ -1701,6 +1699,8 @@ static int tomoyo_read_pid(struct tomoyo_io_buffer *head)
    > * @head: Pointer to "struct tomoyo_io_buffer".
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_write_exception_policy(struct tomoyo_io_buffer *head)
    > {
    > @@ -1735,6 +1735,8 @@ static int tomoyo_write_exception_policy(struct tomoyo_io_buffer *head)
    > * @head: Pointer to "struct tomoyo_io_buffer".
    > *
    > * Returns 0 on success, -EINVAL otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_read_exception_policy(struct tomoyo_io_buffer *head)
    > {
    > @@ -1864,15 +1866,13 @@ void tomoyo_load_policy(const char *filename)
    > tomoyo_policy_loaded = true;
    > { /* Check all profiles currently assigned to domains are defined. */
    > struct tomoyo_domain_info *domain;
    > - down_read(&tomoyo_domain_list_lock);
    > - list_for_each_entry(domain, &tomoyo_domain_list, list) {
    > + list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
    > const u8 profile = domain->profile;
    > if (tomoyo_profile_ptr[profile])
    > continue;
    > panic("Profile %u (used by '%s') not defined.\n",
    > profile, domain->domainname->name);
    > }
    > - up_read(&tomoyo_domain_list_lock);
    > }
    > }
    >
    > @@ -1920,6 +1920,8 @@ static int tomoyo_read_self_domain(struct tomoyo_io_buffer *head)
    > * @file: Pointer to "struct file".
    > *
    > * Associates policy handler and returns 0 on success, -ENOMEM otherwise.
    > + *
    > + * Caller acquires tomoyo_read_lock().
    > */
    > static int tomoyo_open_control(const u8 type, struct file *file)
    > {
    > @@ -2005,6 +2007,7 @@ static int tomoyo_open_control(const u8 type, struct file *file)
    > return -ENOMEM;
    > }
    > }
    > + head->reader_idx = tomoyo_read_lock();
    > file->private_data = head;
    > /*
    > * Call the handler now if the file is
    > @@ -2026,6 +2029,8 @@ static int tomoyo_open_control(const u8 type, struct file *file)
    > * @buffer_len: Size of @buffer.
    > *
    > * Returns bytes read on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_read_control(struct file *file, char __user *buffer,
    > const int buffer_len)
    > @@ -2069,6 +2074,8 @@ static int tomoyo_read_control(struct file *file, char __user *buffer,
    > * @buffer_len: Size of @buffer.
    > *
    > * Returns @buffer_len on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_write_control(struct file *file, const char __user *buffer,
    > const int buffer_len)
    > @@ -2119,11 +2126,14 @@ static int tomoyo_write_control(struct file *file, const char __user *buffer,
    > * @file: Pointer to "struct file".
    > *
    > * Releases memory and returns 0.
    > + *
    > + * Caller looses tomoyo_read_lock().
    > */
    > static int tomoyo_close_control(struct file *file)
    > {
    > struct tomoyo_io_buffer *head = file->private_data;
    >
    > + tomoyo_read_unlock(head->reader_idx);
    > /* Release memory used for policy I/O. */
    > tomoyo_free(head->read_buf);
    > head->read_buf = NULL;
    > diff --git a/security/tomoyo/common.h b/security/tomoyo/common.h
    > index bd10f9f..c6f1392 100644
    > --- a/security/tomoyo/common.h
    > +++ b/security/tomoyo/common.h
    > @@ -269,6 +269,8 @@ struct tomoyo_io_buffer {
    > int (*write) (struct tomoyo_io_buffer *);
    > /* Exclusive lock for this structure. */
    > struct mutex io_sem;
    > + /* Index returned by tomoyo_read_lock(). */
    > + int reader_idx;
    > /* The position currently reading from. */
    > struct list_head *read_var1;
    > /* Extra variables for reading. */
    > @@ -446,16 +448,28 @@ extern struct tomoyo_domain_info tomoyo_kernel_domain;
    > * @cookie: the &struct list_head to use as a cookie.
    > * @head: the head for your list.
    > *
    > - * Same with list_for_each() except that this primitive uses @cookie
    > + * Same with list_for_each_rcu() except that this primitive uses @cookie
    > * so that we can continue iteration.
    > * @cookie must be NULL when iteration starts, and @cookie will become
    > * NULL when iteration finishes.
    > */
    > -#define list_for_each_cookie(pos, cookie, head) \
    > - for (({ if (!cookie) \
    > - cookie = head; }), \
    > - pos = (cookie)->next; \
    > - prefetch(pos->next), pos != (head) || ((cookie) = NULL); \
    > - (cookie) = pos, pos = pos->next)
    > +#define list_for_each_cookie(pos, cookie, head) \
    > + for (({ if (!cookie) \
    > + cookie = head; }), \
    > + pos = rcu_dereference((cookie)->next); \
    > + prefetch(pos->next), pos != (head) || ((cookie) = NULL); \
    > + (cookie) = pos, pos = rcu_dereference(pos->next))
    > +
    > +extern struct srcu_struct tomoyo_ss;
    > +
    > +static inline int tomoyo_read_lock(void)
    > +{
    > + return srcu_read_lock(&tomoyo_ss);
    > +}
    > +
    > +static inline void tomoyo_read_unlock(int idx)
    > +{
    > + srcu_read_unlock(&tomoyo_ss, idx);
    > +}
    >
    > #endif /* !defined(_SECURITY_TOMOYO_COMMON_H) */
    > diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c
    > index fcf52ac..2fd1901 100644
    > --- a/security/tomoyo/domain.c
    > +++ b/security/tomoyo/domain.c
    > @@ -217,6 +217,8 @@ static DECLARE_RWSEM(tomoyo_domain_initializer_list_lock);
    > * @is_delete: True if it is a delete request.
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_update_domain_initializer_entry(const char *domainname,
    > const char *program,
    > @@ -246,7 +248,7 @@ static int tomoyo_update_domain_initializer_entry(const char *domainname,
    > if (!saved_program)
    > return -ENOMEM;
    > down_write(&tomoyo_domain_initializer_list_lock);
    > - list_for_each_entry(ptr, &tomoyo_domain_initializer_list, list) {
    > + list_for_each_entry_rcu(ptr, &tomoyo_domain_initializer_list, list) {
    > if (ptr->is_not != is_not ||
    > ptr->domainname != saved_domainname ||
    > ptr->program != saved_program)
    > @@ -266,7 +268,7 @@ static int tomoyo_update_domain_initializer_entry(const char *domainname,
    > new_entry->program = saved_program;
    > new_entry->is_not = is_not;
    > new_entry->is_last_name = is_last_name;
    > - list_add_tail(&new_entry->list, &tomoyo_domain_initializer_list);
    > + list_add_tail_rcu(&new_entry->list, &tomoyo_domain_initializer_list);
    > error = 0;
    > out:
    > up_write(&tomoyo_domain_initializer_list_lock);
    > @@ -279,13 +281,14 @@ static int tomoyo_update_domain_initializer_entry(const char *domainname,
    > * @head: Pointer to "struct tomoyo_io_buffer".
    > *
    > * Returns true on success, false otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > bool tomoyo_read_domain_initializer_policy(struct tomoyo_io_buffer *head)
    > {
    > struct list_head *pos;
    > bool done = true;
    >
    > - down_read(&tomoyo_domain_initializer_list_lock);
    > list_for_each_cookie(pos, head->read_var2,
    > &tomoyo_domain_initializer_list) {
    > const char *no;
    > @@ -308,7 +311,6 @@ bool tomoyo_read_domain_initializer_policy(struct tomoyo_io_buffer *head)
    > if (!done)
    > break;
    > }
    > - up_read(&tomoyo_domain_initializer_list_lock);
    > return done;
    > }
    >
    > @@ -320,6 +322,8 @@ bool tomoyo_read_domain_initializer_policy(struct tomoyo_io_buffer *head)
    > * @is_delete: True if it is a delete request.
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > int tomoyo_write_domain_initializer_policy(char *data, const bool is_not,
    > const bool is_delete)
    > @@ -345,6 +349,8 @@ int tomoyo_write_domain_initializer_policy(char *data, const bool is_not,
    > *
    > * Returns true if executing @program reinitializes domain transition,
    > * false otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static bool tomoyo_is_domain_initializer(const struct tomoyo_path_info *
    > domainname,
    > @@ -355,8 +361,7 @@ static bool tomoyo_is_domain_initializer(const struct tomoyo_path_info *
    > struct tomoyo_domain_initializer_entry *ptr;
    > bool flag = false;
    >
    > - down_read(&tomoyo_domain_initializer_list_lock);
    > - list_for_each_entry(ptr, &tomoyo_domain_initializer_list, list) {
    > + list_for_each_entry_rcu(ptr, &tomoyo_domain_initializer_list, list) {
    > if (ptr->is_deleted)
    > continue;
    > if (ptr->domainname) {
    > @@ -376,7 +381,6 @@ static bool tomoyo_is_domain_initializer(const struct tomoyo_path_info *
    > }
    > flag = true;
    > }
    > - up_read(&tomoyo_domain_initializer_list_lock);
    > return flag;
    > }
    >
    > @@ -430,6 +434,8 @@ static DECLARE_RWSEM(tomoyo_domain_keeper_list_lock);
    > * @is_delete: True if it is a delete request.
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_update_domain_keeper_entry(const char *domainname,
    > const char *program,
    > @@ -459,7 +465,7 @@ static int tomoyo_update_domain_keeper_entry(const char *domainname,
    > if (!saved_domainname)
    > return -ENOMEM;
    > down_write(&tomoyo_domain_keeper_list_lock);
    > - list_for_each_entry(ptr, &tomoyo_domain_keeper_list, list) {
    > + list_for_each_entry_rcu(ptr, &tomoyo_domain_keeper_list, list) {
    > if (ptr->is_not != is_not ||
    > ptr->domainname != saved_domainname ||
    > ptr->program != saved_program)
    > @@ -479,7 +485,7 @@ static int tomoyo_update_domain_keeper_entry(const char *domainname,
    > new_entry->program = saved_program;
    > new_entry->is_not = is_not;
    > new_entry->is_last_name = is_last_name;
    > - list_add_tail(&new_entry->list, &tomoyo_domain_keeper_list);
    > + list_add_tail_rcu(&new_entry->list, &tomoyo_domain_keeper_list);
    > error = 0;
    > out:
    > up_write(&tomoyo_domain_keeper_list_lock);
    > @@ -493,6 +499,7 @@ static int tomoyo_update_domain_keeper_entry(const char *domainname,
    > * @is_not: True if it is "no_keep_domain" entry.
    > * @is_delete: True if it is a delete request.
    > *
    > + * Caller holds tomoyo_read_lock().
    > */
    > int tomoyo_write_domain_keeper_policy(char *data, const bool is_not,
    > const bool is_delete)
    > @@ -513,13 +520,14 @@ int tomoyo_write_domain_keeper_policy(char *data, const bool is_not,
    > * @head: Pointer to "struct tomoyo_io_buffer".
    > *
    > * Returns true on success, false otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > bool tomoyo_read_domain_keeper_policy(struct tomoyo_io_buffer *head)
    > {
    > struct list_head *pos;
    > bool done = true;
    >
    > - down_read(&tomoyo_domain_keeper_list_lock);
    > list_for_each_cookie(pos, head->read_var2,
    > &tomoyo_domain_keeper_list) {
    > struct tomoyo_domain_keeper_entry *ptr;
    > @@ -542,7 +550,6 @@ bool tomoyo_read_domain_keeper_policy(struct tomoyo_io_buffer *head)
    > if (!done)
    > break;
    > }
    > - up_read(&tomoyo_domain_keeper_list_lock);
    > return done;
    > }
    >
    > @@ -555,6 +562,8 @@ bool tomoyo_read_domain_keeper_policy(struct tomoyo_io_buffer *head)
    > *
    > * Returns true if executing @program supresses domain transition,
    > * false otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static bool tomoyo_is_domain_keeper(const struct tomoyo_path_info *domainname,
    > const struct tomoyo_path_info *program,
    > @@ -563,8 +572,7 @@ static bool tomoyo_is_domain_keeper(const struct tomoyo_path_info *domainname,
    > struct tomoyo_domain_keeper_entry *ptr;
    > bool flag = false;
    >
    > - down_read(&tomoyo_domain_keeper_list_lock);
    > - list_for_each_entry(ptr, &tomoyo_domain_keeper_list, list) {
    > + list_for_each_entry_rcu(ptr, &tomoyo_domain_keeper_list, list) {
    > if (ptr->is_deleted)
    > continue;
    > if (!ptr->is_last_name) {
    > @@ -582,7 +590,6 @@ static bool tomoyo_is_domain_keeper(const struct tomoyo_path_info *domainname,
    > }
    > flag = true;
    > }
    > - up_read(&tomoyo_domain_keeper_list_lock);
    > return flag;
    > }
    >
    > @@ -627,6 +634,8 @@ static DECLARE_RWSEM(tomoyo_alias_list_lock);
    > * @is_delete: True if it is a delete request.
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_update_alias_entry(const char *original_name,
    > const char *aliased_name,
    > @@ -646,7 +655,7 @@ static int tomoyo_update_alias_entry(const char *original_name,
    > if (!saved_original_name || !saved_aliased_name)
    > return -ENOMEM;
    > down_write(&tomoyo_alias_list_lock);
    > - list_for_each_entry(ptr, &tomoyo_alias_list, list) {
    > + list_for_each_entry_rcu(ptr, &tomoyo_alias_list, list) {
    > if (ptr->original_name != saved_original_name ||
    > ptr->aliased_name != saved_aliased_name)
    > continue;
    > @@ -663,7 +672,7 @@ static int tomoyo_update_alias_entry(const char *original_name,
    > goto out;
    > new_entry->original_name = saved_original_name;
    > new_entry->aliased_name = saved_aliased_name;
    > - list_add_tail(&new_entry->list, &tomoyo_alias_list);
    > + list_add_tail_rcu(&new_entry->list, &tomoyo_alias_list);
    > error = 0;
    > out:
    > up_write(&tomoyo_alias_list_lock);
    > @@ -676,13 +685,14 @@ static int tomoyo_update_alias_entry(const char *original_name,
    > * @head: Pointer to "struct tomoyo_io_buffer".
    > *
    > * Returns true on success, false otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > bool tomoyo_read_alias_policy(struct tomoyo_io_buffer *head)
    > {
    > struct list_head *pos;
    > bool done = true;
    >
    > - down_read(&tomoyo_alias_list_lock);
    > list_for_each_cookie(pos, head->read_var2, &tomoyo_alias_list) {
    > struct tomoyo_alias_entry *ptr;
    >
    > @@ -695,7 +705,6 @@ bool tomoyo_read_alias_policy(struct tomoyo_io_buffer *head)
    > if (!done)
    > break;
    > }
    > - up_read(&tomoyo_alias_list_lock);
    > return done;
    > }
    >
    > @@ -706,6 +715,8 @@ bool tomoyo_read_alias_policy(struct tomoyo_io_buffer *head)
    > * @is_delete: True if it is a delete request.
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > int tomoyo_write_alias_policy(char *data, const bool is_delete)
    > {
    > @@ -724,6 +735,8 @@ int tomoyo_write_alias_policy(char *data, const bool is_delete)
    > * @profile: Profile number to assign if the domain was newly created.
    > *
    > * Returns pointer to "struct tomoyo_domain_info" on success, NULL otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > struct tomoyo_domain_info *tomoyo_find_or_assign_new_domain(const char *
    > domainname,
    > @@ -742,7 +755,7 @@ struct tomoyo_domain_info *tomoyo_find_or_assign_new_domain(const char *
    > if (!saved_domainname)
    > goto out;
    > /* Can I reuse memory of deleted domain? */
    > - list_for_each_entry(domain, &tomoyo_domain_list, list) {
    > + list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
    > struct task_struct *p;
    > struct tomoyo_acl_info *ptr;
    > bool flag;
    > @@ -760,7 +773,7 @@ struct tomoyo_domain_info *tomoyo_find_or_assign_new_domain(const char *
    > read_unlock(&tasklist_lock);
    > if (flag)
    > continue;
    > - list_for_each_entry(ptr, &domain->acl_info_list, list) {
    > + list_for_each_entry_rcu(ptr, &domain->acl_info_list, list) {
    > ptr->type |= TOMOYO_ACL_DELETED;
    > }
    > tomoyo_set_domain_flag(domain, true, domain->flags);
    > @@ -776,7 +789,7 @@ struct tomoyo_domain_info *tomoyo_find_or_assign_new_domain(const char *
    > INIT_LIST_HEAD(&domain->acl_info_list);
    > domain->domainname = saved_domainname;
    > domain->profile = profile;
    > - list_add_tail(&domain->list, &tomoyo_domain_list);
    > + list_add_tail_rcu(&domain->list, &tomoyo_domain_list);
    > }
    > out:
    > up_write(&tomoyo_domain_list_lock);
    > @@ -789,6 +802,8 @@ struct tomoyo_domain_info *tomoyo_find_or_assign_new_domain(const char *
    > * @bprm: Pointer to "struct linux_binprm".
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > int tomoyo_find_next_domain(struct linux_binprm *bprm)
    > {
    > @@ -849,8 +864,7 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
    > if (tomoyo_pathcmp(&r, &s)) {
    > struct tomoyo_alias_entry *ptr;
    > /* Is this program allowed to be called via symbolic links? */
    > - down_read(&tomoyo_alias_list_lock);
    > - list_for_each_entry(ptr, &tomoyo_alias_list, list) {
    > + list_for_each_entry_rcu(ptr, &tomoyo_alias_list, list) {
    > if (ptr->is_deleted ||
    > tomoyo_pathcmp(&r, ptr->original_name) ||
    > tomoyo_pathcmp(&s, ptr->aliased_name))
    > @@ -861,7 +875,6 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
    > tomoyo_fill_path_info(&r);
    > break;
    > }
    > - up_read(&tomoyo_alias_list_lock);
    > }
    >
    > /* Check execute permission. */
    > @@ -892,9 +905,7 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
    > }
    > if (domain || strlen(new_domain_name) >= TOMOYO_MAX_PATHNAME_LEN)
    > goto done;
    > - down_read(&tomoyo_domain_list_lock);
    > domain = tomoyo_find_domain(new_domain_name);
    > - up_read(&tomoyo_domain_list_lock);
    > if (domain)
    > goto done;
    > if (is_enforce)
    > diff --git a/security/tomoyo/file.c b/security/tomoyo/file.c
    > index 482f0e7..3c47286 100644
    > --- a/security/tomoyo/file.c
    > +++ b/security/tomoyo/file.c
    > @@ -213,6 +213,8 @@ static DECLARE_RWSEM(tomoyo_globally_readable_list_lock);
    > * @is_delete: True if it is a delete request.
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_update_globally_readable_entry(const char *filename,
    > const bool is_delete)
    > @@ -228,7 +230,7 @@ static int tomoyo_update_globally_readable_entry(const char *filename,
    > if (!saved_filename)
    > return -ENOMEM;
    > down_write(&tomoyo_globally_readable_list_lock);
    > - list_for_each_entry(ptr, &tomoyo_globally_readable_list, list) {
    > + list_for_each_entry_rcu(ptr, &tomoyo_globally_readable_list, list) {
    > if (ptr->filename != saved_filename)
    > continue;
    > ptr->is_deleted = is_delete;
    > @@ -243,7 +245,7 @@ static int tomoyo_update_globally_readable_entry(const char *filename,
    > if (!new_entry)
    > goto out;
    > new_entry->filename = saved_filename;
    > - list_add_tail(&new_entry->list, &tomoyo_globally_readable_list);
    > + list_add_tail_rcu(&new_entry->list, &tomoyo_globally_readable_list);
    > error = 0;
    > out:
    > up_write(&tomoyo_globally_readable_list_lock);
    > @@ -256,21 +258,22 @@ static int tomoyo_update_globally_readable_entry(const char *filename,
    > * @filename: The filename to check.
    > *
    > * Returns true if any domain can open @filename for reading, false otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static bool tomoyo_is_globally_readable_file(const struct tomoyo_path_info *
    > filename)
    > {
    > struct tomoyo_globally_readable_file_entry *ptr;
    > bool found = false;
    > - down_read(&tomoyo_globally_readable_list_lock);
    > - list_for_each_entry(ptr, &tomoyo_globally_readable_list, list) {
    > +
    > + list_for_each_entry_rcu(ptr, &tomoyo_globally_readable_list, list) {
    > if (!ptr->is_deleted &&
    > tomoyo_path_matches_pattern(filename, ptr->filename)) {
    > found = true;
    > break;
    > }
    > }
    > - up_read(&tomoyo_globally_readable_list_lock);
    > return found;
    > }
    >
    > @@ -281,6 +284,8 @@ static bool tomoyo_is_globally_readable_file(const struct tomoyo_path_info *
    > * @is_delete: True if it is a delete request.
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > int tomoyo_write_globally_readable_policy(char *data, const bool is_delete)
    > {
    > @@ -293,13 +298,14 @@ int tomoyo_write_globally_readable_policy(char *data, const bool is_delete)
    > * @head: Pointer to "struct tomoyo_io_buffer".
    > *
    > * Returns true on success, false otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > bool tomoyo_read_globally_readable_policy(struct tomoyo_io_buffer *head)
    > {
    > struct list_head *pos;
    > bool done = true;
    >
    > - down_read(&tomoyo_globally_readable_list_lock);
    > list_for_each_cookie(pos, head->read_var2,
    > &tomoyo_globally_readable_list) {
    > struct tomoyo_globally_readable_file_entry *ptr;
    > @@ -313,7 +319,6 @@ bool tomoyo_read_globally_readable_policy(struct tomoyo_io_buffer *head)
    > if (!done)
    > break;
    > }
    > - up_read(&tomoyo_globally_readable_list_lock);
    > return done;
    > }
    >
    > @@ -356,6 +361,8 @@ static DECLARE_RWSEM(tomoyo_pattern_list_lock);
    > * @is_delete: True if it is a delete request.
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_update_file_pattern_entry(const char *pattern,
    > const bool is_delete)
    > @@ -371,7 +378,7 @@ static int tomoyo_update_file_pattern_entry(const char *pattern,
    > if (!saved_pattern)
    > return -ENOMEM;
    > down_write(&tomoyo_pattern_list_lock);
    > - list_for_each_entry(ptr, &tomoyo_pattern_list, list) {
    > + list_for_each_entry_rcu(ptr, &tomoyo_pattern_list, list) {
    > if (saved_pattern != ptr->pattern)
    > continue;
    > ptr->is_deleted = is_delete;
    > @@ -386,7 +393,7 @@ static int tomoyo_update_file_pattern_entry(const char *pattern,
    > if (!new_entry)
    > goto out;
    > new_entry->pattern = saved_pattern;
    > - list_add_tail(&new_entry->list, &tomoyo_pattern_list);
    > + list_add_tail_rcu(&new_entry->list, &tomoyo_pattern_list);
    > error = 0;
    > out:
    > up_write(&tomoyo_pattern_list_lock);
    > @@ -399,6 +406,8 @@ static int tomoyo_update_file_pattern_entry(const char *pattern,
    > * @filename: The filename to find patterned pathname.
    > *
    > * Returns pointer to pathname pattern if matched, @filename otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static const struct tomoyo_path_info *
    > tomoyo_get_file_pattern(const struct tomoyo_path_info *filename)
    > @@ -406,8 +415,7 @@ tomoyo_get_file_pattern(const struct tomoyo_path_info *filename)
    > struct tomoyo_pattern_entry *ptr;
    > const struct tomoyo_path_info *pattern = NULL;
    >
    > - down_read(&tomoyo_pattern_list_lock);
    > - list_for_each_entry(ptr, &tomoyo_pattern_list, list) {
    > + list_for_each_entry_rcu(ptr, &tomoyo_pattern_list, list) {
    > if (ptr->is_deleted)
    > continue;
    > if (!tomoyo_path_matches_pattern(filename, ptr->pattern))
    > @@ -420,7 +428,6 @@ tomoyo_get_file_pattern(const struct tomoyo_path_info *filename)
    > break;
    > }
    > }
    > - up_read(&tomoyo_pattern_list_lock);
    > if (pattern)
    > filename = pattern;
    > return filename;
    > @@ -433,6 +440,8 @@ tomoyo_get_file_pattern(const struct tomoyo_path_info *filename)
    > * @is_delete: True if it is a delete request.
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > int tomoyo_write_pattern_policy(char *data, const bool is_delete)
    > {
    > @@ -445,13 +454,14 @@ int tomoyo_write_pattern_policy(char *data, const bool is_delete)
    > * @head: Pointer to "struct tomoyo_io_buffer".
    > *
    > * Returns true on success, false otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > bool tomoyo_read_file_pattern(struct tomoyo_io_buffer *head)
    > {
    > struct list_head *pos;
    > bool done = true;
    >
    > - down_read(&tomoyo_pattern_list_lock);
    > list_for_each_cookie(pos, head->read_var2, &tomoyo_pattern_list) {
    > struct tomoyo_pattern_entry *ptr;
    > ptr = list_entry(pos, struct tomoyo_pattern_entry, list);
    > @@ -462,7 +472,6 @@ bool tomoyo_read_file_pattern(struct tomoyo_io_buffer *head)
    > if (!done)
    > break;
    > }
    > - up_read(&tomoyo_pattern_list_lock);
    > return done;
    > }
    >
    > @@ -505,6 +514,8 @@ static DECLARE_RWSEM(tomoyo_no_rewrite_list_lock);
    > * @is_delete: True if it is a delete request.
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_update_no_rewrite_entry(const char *pattern,
    > const bool is_delete)
    > @@ -519,7 +530,7 @@ static int tomoyo_update_no_rewrite_entry(const char *pattern,
    > if (!saved_pattern)
    > return -ENOMEM;
    > down_write(&tomoyo_no_rewrite_list_lock);
    > - list_for_each_entry(ptr, &tomoyo_no_rewrite_list, list) {
    > + list_for_each_entry_rcu(ptr, &tomoyo_no_rewrite_list, list) {
    > if (ptr->pattern != saved_pattern)
    > continue;
    > ptr->is_deleted = is_delete;
    > @@ -534,7 +545,7 @@ static int tomoyo_update_no_rewrite_entry(const char *pattern,
    > if (!new_entry)
    > goto out;
    > new_entry->pattern = saved_pattern;
    > - list_add_tail(&new_entry->list, &tomoyo_no_rewrite_list);
    > + list_add_tail_rcu(&new_entry->list, &tomoyo_no_rewrite_list);
    > error = 0;
    > out:
    > up_write(&tomoyo_no_rewrite_list_lock);
    > @@ -548,14 +559,15 @@ static int tomoyo_update_no_rewrite_entry(const char *pattern,
    > *
    > * Returns true if @filename is specified by "deny_rewrite" directive,
    > * false otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static bool tomoyo_is_no_rewrite_file(const struct tomoyo_path_info *filename)
    > {
    > struct tomoyo_no_rewrite_entry *ptr;
    > bool found = false;
    >
    > - down_read(&tomoyo_no_rewrite_list_lock);
    > - list_for_each_entry(ptr, &tomoyo_no_rewrite_list, list) {
    > + list_for_each_entry_rcu(ptr, &tomoyo_no_rewrite_list, list) {
    > if (ptr->is_deleted)
    > continue;
    > if (!tomoyo_path_matches_pattern(filename, ptr->pattern))
    > @@ -563,7 +575,6 @@ static bool tomoyo_is_no_rewrite_file(const struct tomoyo_path_info *filename)
    > found = true;
    > break;
    > }
    > - up_read(&tomoyo_no_rewrite_list_lock);
    > return found;
    > }
    >
    > @@ -574,6 +585,8 @@ static bool tomoyo_is_no_rewrite_file(const struct tomoyo_path_info *filename)
    > * @is_delete: True if it is a delete request.
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > int tomoyo_write_no_rewrite_policy(char *data, const bool is_delete)
    > {
    > @@ -586,13 +599,14 @@ int tomoyo_write_no_rewrite_policy(char *data, const bool is_delete)
    > * @head: Pointer to "struct tomoyo_io_buffer".
    > *
    > * Returns true on success, false otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > bool tomoyo_read_no_rewrite_policy(struct tomoyo_io_buffer *head)
    > {
    > struct list_head *pos;
    > bool done = true;
    >
    > - down_read(&tomoyo_no_rewrite_list_lock);
    > list_for_each_cookie(pos, head->read_var2, &tomoyo_no_rewrite_list) {
    > struct tomoyo_no_rewrite_entry *ptr;
    > ptr = list_entry(pos, struct tomoyo_no_rewrite_entry, list);
    > @@ -603,7 +617,6 @@ bool tomoyo_read_no_rewrite_policy(struct tomoyo_io_buffer *head)
    > if (!done)
    > break;
    > }
    > - up_read(&tomoyo_no_rewrite_list_lock);
    > return done;
    > }
    >
    > @@ -621,6 +634,8 @@ bool tomoyo_read_no_rewrite_policy(struct tomoyo_io_buffer *head)
    > * Current policy syntax uses "allow_read/write" instead of "6",
    > * "allow_read" instead of "4", "allow_write" instead of "2",
    > * "allow_execute" instead of "1".
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_update_file_acl(const char *filename, u8 perm,
    > struct tomoyo_domain_info * const domain,
    > @@ -658,6 +673,8 @@ static int tomoyo_update_file_acl(const char *filename, u8 perm,
    > * @may_use_pattern: True if patterned ACL is permitted.
    > *
    > * Returns 0 on success, -EPERM otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_check_single_path_acl2(const struct tomoyo_domain_info *
    > domain,
    > @@ -669,8 +686,7 @@ static int tomoyo_check_single_path_acl2(const struct tomoyo_domain_info *
    > struct tomoyo_acl_info *ptr;
    > int error = -EPERM;
    >
    > - down_read(&tomoyo_domain_acl_info_list_lock);
    > - list_for_each_entry(ptr, &domain->acl_info_list, list) {
    > + list_for_each_entry_rcu(ptr, &domain->acl_info_list, list) {
    > struct tomoyo_single_path_acl_record *acl;
    > if (tomoyo_acl_type2(ptr) != TOMOYO_TYPE_SINGLE_PATH_ACL)
    > continue;
    > @@ -693,7 +709,6 @@ static int tomoyo_check_single_path_acl2(const struct tomoyo_domain_info *
    > error = 0;
    > break;
    > }
    > - up_read(&tomoyo_domain_acl_info_list_lock);
    > return error;
    > }
    >
    > @@ -705,6 +720,8 @@ static int tomoyo_check_single_path_acl2(const struct tomoyo_domain_info *
    > * @operation: Mode ("read" or "write" or "read/write" or "execute").
    > *
    > * Returns 0 on success, -EPERM otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_check_file_acl(const struct tomoyo_domain_info *domain,
    > const struct tomoyo_path_info *filename,
    > @@ -738,6 +755,8 @@ static int tomoyo_check_file_acl(const struct tomoyo_domain_info *domain,
    > * @mode: Access control mode.
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_check_file_perm2(struct tomoyo_domain_info * const domain,
    > const struct tomoyo_path_info *filename,
    > @@ -791,6 +810,8 @@ static int tomoyo_check_file_perm2(struct tomoyo_domain_info * const domain,
    > * @is_delete: True if it is a delete request.
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > int tomoyo_write_file_policy(char *data, struct tomoyo_domain_info *domain,
    > const bool is_delete)
    > @@ -838,6 +859,8 @@ int tomoyo_write_file_policy(char *data, struct tomoyo_domain_info *domain,
    > * @is_delete: True if it is a delete request.
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_update_single_path_acl(const u8 type, const char *filename,
    > struct tomoyo_domain_info *
    > @@ -861,7 +884,7 @@ static int tomoyo_update_single_path_acl(const u8 type, const char *filename,
    > down_write(&tomoyo_domain_acl_info_list_lock);
    > if (is_delete)
    > goto delete;
    > - list_for_each_entry(ptr, &domain->acl_info_list, list) {
    > + list_for_each_entry_rcu(ptr, &domain->acl_info_list, list) {
    > if (tomoyo_acl_type1(ptr) != TOMOYO_TYPE_SINGLE_PATH_ACL)
    > continue;
    > acl = container_of(ptr, struct tomoyo_single_path_acl_record,
    > @@ -894,12 +917,12 @@ static int tomoyo_update_single_path_acl(const u8 type, const char *filename,
    > if (perm == (1 << TOMOYO_TYPE_READ_WRITE_ACL))
    > acl->perm |= rw_mask;
    > acl->filename = saved_filename;
    > - list_add_tail(&acl->head.list, &domain->acl_info_list);
    > + list_add_tail_rcu(&acl->head.list, &domain->acl_info_list);
    > error = 0;
    > goto out;
    > delete:
    > error = -ENOENT;
    > - list_for_each_entry(ptr, &domain->acl_info_list, list) {
    > + list_for_each_entry_rcu(ptr, &domain->acl_info_list, list) {
    > if (tomoyo_acl_type2(ptr) != TOMOYO_TYPE_SINGLE_PATH_ACL)
    > continue;
    > acl = container_of(ptr, struct tomoyo_single_path_acl_record,
    > @@ -934,6 +957,8 @@ static int tomoyo_update_single_path_acl(const u8 type, const char *filename,
    > * @is_delete: True if it is a delete request.
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_update_double_path_acl(const u8 type, const char *filename1,
    > const char *filename2,
    > @@ -959,7 +984,7 @@ static int tomoyo_update_double_path_acl(const u8 type, const char *filename1,
    > down_write(&tomoyo_domain_acl_info_list_lock);
    > if (is_delete)
    > goto delete;
    > - list_for_each_entry(ptr, &domain->acl_info_list, list) {
    > + list_for_each_entry_rcu(ptr, &domain->acl_info_list, list) {
    > if (tomoyo_acl_type1(ptr) != TOMOYO_TYPE_DOUBLE_PATH_ACL)
    > continue;
    > acl = container_of(ptr, struct tomoyo_double_path_acl_record,
    > @@ -982,12 +1007,12 @@ static int tomoyo_update_double_path_acl(const u8 type, const char *filename1,
    > acl->perm = perm;
    > acl->filename1 = saved_filename1;
    > acl->filename2 = saved_filename2;
    > - list_add_tail(&acl->head.list, &domain->acl_info_list);
    > + list_add_tail_rcu(&acl->head.list, &domain->acl_info_list);
    > error = 0;
    > goto out;
    > delete:
    > error = -ENOENT;
    > - list_for_each_entry(ptr, &domain->acl_info_list, list) {
    > + list_for_each_entry_rcu(ptr, &domain->acl_info_list, list) {
    > if (tomoyo_acl_type2(ptr) != TOMOYO_TYPE_DOUBLE_PATH_ACL)
    > continue;
    > acl = container_of(ptr, struct tomoyo_double_path_acl_record,
    > @@ -1014,6 +1039,8 @@ static int tomoyo_update_double_path_acl(const u8 type, const char *filename1,
    > * @filename: Filename to check.
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_check_single_path_acl(struct tomoyo_domain_info *domain,
    > const u8 type,
    > @@ -1033,6 +1060,8 @@ static int tomoyo_check_single_path_acl(struct tomoyo_domain_info *domain,
    > * @filename2: Second filename to check.
    > *
    > * Returns 0 on success, -EPERM otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_check_double_path_acl(const struct tomoyo_domain_info *domain,
    > const u8 type,
    > @@ -1047,8 +1076,7 @@ static int tomoyo_check_double_path_acl(const struct tomoyo_domain_info *domain,
    >
    > if (!tomoyo_check_flags(domain, TOMOYO_MAC_FOR_FILE))
    > return 0;
    > - down_read(&tomoyo_domain_acl_info_list_lock);
    > - list_for_each_entry(ptr, &domain->acl_info_list, list) {
    > + list_for_each_entry_rcu(ptr, &domain->acl_info_list, list) {
    > struct tomoyo_double_path_acl_record *acl;
    > if (tomoyo_acl_type2(ptr) != TOMOYO_TYPE_DOUBLE_PATH_ACL)
    > continue;
    > @@ -1063,7 +1091,6 @@ static int tomoyo_check_double_path_acl(const struct tomoyo_domain_info *domain,
    > error = 0;
    > break;
    > }
    > - up_read(&tomoyo_domain_acl_info_list_lock);
    > return error;
    > }
    >
    > @@ -1076,6 +1103,8 @@ static int tomoyo_check_double_path_acl(const struct tomoyo_domain_info *domain,
    > * @mode: Access control mode.
    > *
    > * Returns 0 on success, negative value otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > static int tomoyo_check_single_path_permission2(struct tomoyo_domain_info *
    > const domain, u8 operation,
    > @@ -1124,6 +1153,8 @@ static int tomoyo_check_single_path_permission2(struct tomoyo_domain_info *
    > * @filename: Check permission for "execute".
    > *
    > * Returns 0 on success, negativevalue otherwise.
    > + *
    > + * Caller holds tomoyo_read_lock().
    > */
    > int tomoyo_check_exec_perm(struct tomoyo_domain_info *domain,
    > const struct tomoyo_path_info *filename)
    > @@ -1152,6 +1183,7 @@ int tomoyo_check_open_permission(struct tomoyo_domain_info *domain,
    > struct tomoyo_path_info *buf;
    > const u8 mode = tomoyo_check_flags(domain, TOMOYO_MAC_FOR_FILE);
    > const bool is_enforce = (mode == 3);
    > + int idx;
    >
    > if (!mode || !path->mnt)
    > return 0;
    > @@ -1163,6 +1195,7 @@ int tomoyo_check_open_permission(struct tomoyo_domain_info *domain,
    > * don't call me.
    > */
    > return 0;
    > + idx = tomoyo_read_lock();
    > buf = tomoyo_get_path(path);
    > if (!buf)
    > goto out;
    > @@ -1188,6 +1221,7 @@ int tomoyo_check_open_permission(struct tomoyo_domain_info *domain,
    > buf, mode);
    > out:
    > tomoyo_free(buf);
    > + tomoyo_read_unlock(idx);
    > if (!is_enforce)
    > error = 0;
    > return error;
    > @@ -1209,9 +1243,11 @@ int tomoyo_check_1path_perm(struct tomoyo_domain_info *domain,
    > struct tomoyo_path_info *buf;
    > const u8 mode = tomoyo_check_flags(domain, TOMOYO_MAC_FOR_FILE);
    > const bool is_enforce = (mode == 3);
    > + int idx;
    >
    > if (!mode || !path->mnt)
    > return 0;
    > + idx = tomoyo_read_lock();
    > buf = tomoyo_get_path(path);
    > if (!buf)
    > goto out;
    > @@ -1231,6 +1267,7 @@ int tomoyo_check_1path_perm(struct tomoyo_domain_info *domain,
    > mode);
    > out:
    > tomoyo_free(buf);
    > + tomoyo_read_unlock(idx);
    > if (!is_enforce)
    > error = 0;
    > return error;
    > @@ -1251,9 +1288,12 @@ int tomoyo_check_rewrite_permission(struct tomoyo_domain_info *domain,
    > const u8 mode = tomoyo_check_flags(domain, TOMOYO_MAC_FOR_FILE);
    > const bool is_enforce = (mode == 3);
    > struct tomoyo_path_info *buf;
    > + int idx;
    >
    > if (!mode || !filp->f_path.mnt)
    > return 0;
    > +
    > + idx = tomoyo_read_lock();
    > buf = tomoyo_get_path(&filp->f_path);
    > if (!buf)
    > goto out;
    > @@ -1266,6 +1306,7 @@ int tomoyo_check_rewrite_permission(struct tomoyo_domain_info *domain,
    > buf, mode);
    > out:
    > tomoyo_free(buf);
    > + tomoyo_read_unlock(idx);
    > if (!is_enforce)
    > error = 0;
    > return error;
    > @@ -1290,9 +1331,11 @@ int tomoyo_check_2path_perm(struct tomoyo_domain_info * const domain,
    > const u8 mode = tomoyo_check_flags(domain, TOMOYO_MAC_FOR_FILE);
    > const bool is_enforce = (mode == 3);
    > const char *msg;
    > + int idx;
    >
    > if (!mode || !path1->mnt || !path2->mnt)
    > return 0;
    > + idx = tomoyo_read_lock();
    > buf1 = tomoyo_get_path(path1);
    > buf2 = tomoyo_get_path(path2);
    > if (!buf1 || !buf2)
    > @@ -1331,6 +1374,7 @@ int tomoyo_check_2path_perm(struct tomoyo_domain_info * const domain,
    > out:
    > tomoyo_free(buf1);
    > tomoyo_free(buf2);
    > + tomoyo_read_unlock(idx);
    > if (!is_enforce)
    > error = 0;
    > return error;
    > diff --git a/security/tomoyo/realpath.c b/security/tomoyo/realpath.c
    > index e3c7aa0..62363b3 100644
    > --- a/security/tomoyo/realpath.c
    > +++ b/security/tomoyo/realpath.c
    > @@ -402,11 +402,13 @@ void __init tomoyo_realpath_init(void)
    > INIT_LIST_HEAD(&tomoyo_name_list[i]);
    > INIT_LIST_HEAD(&tomoyo_kernel_domain.acl_info_list);
    > tomoyo_kernel_domain.domainname = tomoyo_save_name(TOMOYO_ROOT_NAME);
    > - list_add_tail(&tomoyo_kernel_domain.list, &tomoyo_domain_list);
    > - down_read(&tomoyo_domain_list_lock);
    > + /*
    > + * tomoyo_read_lock() is not needed because this function is
    > + * called before the first "delete" request.
    > + */
    > + list_add_tail_rcu(&tomoyo_kernel_domain.list, &tomoyo_domain_list);
    > if (tomoyo_find_domain(TOMOYO_ROOT_NAME) != &tomoyo_kernel_domain)
    > panic("Can't register tomoyo_kernel_domain");
    > - up_read(&tomoyo_domain_list_lock);
    > }
    >
    > /* Memory allocated for temporary purpose. */
    > diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c
    > index ad9555f..714daa3 100644
    > --- a/security/tomoyo/tomoyo.c
    > +++ b/security/tomoyo/tomoyo.c
    > @@ -76,8 +76,18 @@ static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
    > * Execute permission is checked against pathname passed to do_execve()
    > * using current domain.
    > */
    > - if (!domain)
    > - return tomoyo_find_next_domain(bprm);
    > + if (!domain) {
    > + /*
    > + * We will need to protect whole execve() operation when GC
    > + * starts kfree()ing "struct tomoyo_domain_info" because
    > + * bprm->cred->security points to "struct tomoyo_domain_info"
    > + * but "struct tomoyo_domain_info" does not have a refcounter.
    > + */
    > + const int idx = tomoyo_read_lock();
    > + const int err = tomoyo_find_next_domain(bprm);
    > + tomoyo_read_unlock(idx);
    > + return err;
    > + }
    > /*
    > * Read permission is checked against interpreters using next domain.
    > * '1' is the result of open_to_namei_flags(O_RDONLY).
    > @@ -278,6 +288,9 @@ static struct security_operations tomoyo_security_ops = {
    > .sb_pivotroot = tomoyo_sb_pivotroot,
    > };
    >
    > +/* Lock for GC. */
    > +struct srcu_struct tomoyo_ss;
    > +
    > static int __init tomoyo_init(void)
    > {
    > struct cred *cred = (struct cred *) current_cred();
    > @@ -285,7 +298,8 @@ static int __init tomoyo_init(void)
    > if (!security_module_enable(&tomoyo_security_ops))
    > return 0;
    > /* register ourselves with the security framework */
    > - if (register_security(&tomoyo_security_ops))
    > + if (register_security(&tomoyo_security_ops) ||
    > + init_srcu_struct(&tomoyo_ss))
    > panic("Failure registering TOMOYO Linux");
    > printk(KERN_INFO "TOMOYO Linux initialized\n");
    > cred->security = &tomoyo_kernel_domain;
    > --
    > To unsubscribe from this list: send the line "unsubscribe linux-security-module" in
    > the body of a message to majordomo@vger.kernel.org
    > More majordomo info at http://vger.kernel.org/majordomo-info.html


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