Re: Suspicious RCU usage in tomoyo code
From: John Garry
Date: Mon Dec 16 2019 - 08:13:58 EST
+
On 16/12/2019 10:30, Tetsuo Handa wrote:
On 2019/12/16 18:20, John Garry wrote:
On 16/12/2019 01:04, Paul E. McKenney wrote:
Thank you for reporting. I was surprised that this warning did not show up.
Something has changed or only some config combination could trigger it ...
Any particular reason we are having this discussion privately?;-)
I did mention this initially - I didn't know if reporting issues in "security" domain is generally always open. Probably being very paranoid or silly of me...
Since this is not a security problem, you can post to public lists.
Anyway, here is a patch. Will you try?
From 8356e05a5822ffad5d374c992bc6af26ea655d6d Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Date: Mon, 16 Dec 2019 19:16:48 +0900
Subject: [PATCH] tomoyo: Add tomoyo: Suppress RCU warning at list_for_each_entry_rcu().
John Garry has reported that allmodconfig kernel on arm64 causes flood of
"RCU-list traversed in non-reader section!!" warning. I don't know what
change caused this warning, but this warning is safe because TOMOYO uses
SRCU lock instead. Let's suppress this warning by explicitly telling that
the caller is holding SRCU lock.
Reported-by: John Garry <john.garry@xxxxxxxxxx>
Yeah, this looks to have fixed it:
Tested-by: John Garry <john.garry@xxxxxxxxxx>
Thanks
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
---
security/tomoyo/common.c | 9 ++++++---
security/tomoyo/domain.c | 15 ++++++++++-----
security/tomoyo/group.c | 9 ++++++---
security/tomoyo/util.c | 6 ++++--
4 files changed, 26 insertions(+), 13 deletions(-)
diff --git a/security/tomoyo/common.c b/security/tomoyo/common.c
index dd3d5942e669..c36bafbcd77e 100644
--- a/security/tomoyo/common.c
+++ b/security/tomoyo/common.c
@@ -951,7 +951,8 @@ static bool tomoyo_manager(void)
exe = tomoyo_get_exe();
if (!exe)
return false;
- list_for_each_entry_rcu(ptr, &tomoyo_kernel_namespace.policy_list[TOMOYO_ID_MANAGER], head.list) {
+ list_for_each_entry_rcu(ptr, &tomoyo_kernel_namespace.policy_list[TOMOYO_ID_MANAGER], head.list,
+ srcu_read_lock_held(&tomoyo_ss)) {
if (!ptr->head.is_deleted &&
(!tomoyo_pathcmp(domainname, ptr->manager) ||
!strcmp(exe, ptr->manager->name))) {
@@ -1095,7 +1096,8 @@ static int tomoyo_delete_domain(char *domainname)
if (mutex_lock_interruptible(&tomoyo_policy_lock))
return -EINTR;
/* Is there an active domain? */
- list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
+ list_for_each_entry_rcu(domain, &tomoyo_domain_list, list,
+ srcu_read_lock_held(&tomoyo_ss)) {
/* Never delete tomoyo_kernel_domain */
if (domain == &tomoyo_kernel_domain)
continue;
@@ -2778,7 +2780,8 @@ void tomoyo_check_profile(void)
tomoyo_policy_loaded = true;
pr_info("TOMOYO: 2.6.0\n");
- list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
+ list_for_each_entry_rcu(domain, &tomoyo_domain_list, list,
+ srcu_read_lock_held(&tomoyo_ss)) {
const u8 profile = domain->profile;
struct tomoyo_policy_namespace *ns = domain->ns;
diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c
index 8526a0a74023..7869d6a9980b 100644
--- a/security/tomoyo/domain.c
+++ b/security/tomoyo/domain.c
@@ -41,7 +41,8 @@ int tomoyo_update_policy(struct tomoyo_acl_head *new_entry, const int size,
if (mutex_lock_interruptible(&tomoyo_policy_lock))
return -ENOMEM;
- list_for_each_entry_rcu(entry, list, list) {
+ list_for_each_entry_rcu(entry, list, list,
+ srcu_read_lock_held(&tomoyo_ss)) {
if (entry->is_deleted == TOMOYO_GC_IN_PROGRESS)
continue;
if (!check_duplicate(entry, new_entry))
@@ -119,7 +120,8 @@ int tomoyo_update_domain(struct tomoyo_acl_info *new_entry, const int size,
}
if (mutex_lock_interruptible(&tomoyo_policy_lock))
goto out;
- list_for_each_entry_rcu(entry, list, list) {
+ list_for_each_entry_rcu(entry, list, list,
+ srcu_read_lock_held(&tomoyo_ss)) {
if (entry->is_deleted == TOMOYO_GC_IN_PROGRESS)
continue;
if (!tomoyo_same_acl_head(entry, new_entry) ||
@@ -166,7 +168,8 @@ void tomoyo_check_acl(struct tomoyo_request_info *r,
u16 i = 0;
retry:
- list_for_each_entry_rcu(ptr, list, list) {
+ list_for_each_entry_rcu(ptr, list, list,
+ srcu_read_lock_held(&tomoyo_ss)) {
if (ptr->is_deleted || ptr->type != r->param_type)
continue;
if (!check_entry(r, ptr))
@@ -298,7 +301,8 @@ static inline bool tomoyo_scan_transition
{
const struct tomoyo_transition_control *ptr;
- list_for_each_entry_rcu(ptr, list, head.list) {
+ list_for_each_entry_rcu(ptr, list, head.list,
+ srcu_read_lock_held(&tomoyo_ss)) {
if (ptr->head.is_deleted || ptr->type != type)
continue;
if (ptr->domainname) {
@@ -735,7 +739,8 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
/* Check 'aggregator' directive. */
candidate = &exename;
- list_for_each_entry_rcu(ptr, list, head.list) {
+ list_for_each_entry_rcu(ptr, list, head.list,
+ srcu_read_lock_held(&tomoyo_ss)) {
if (ptr->head.is_deleted ||
!tomoyo_path_matches_pattern(&exename,
ptr->original_name))
diff --git a/security/tomoyo/group.c b/security/tomoyo/group.c
index a37c7dc66e44..1cecdd797597 100644
--- a/security/tomoyo/group.c
+++ b/security/tomoyo/group.c
@@ -133,7 +133,8 @@ tomoyo_path_matches_group(const struct tomoyo_path_info *pathname,
{
struct tomoyo_path_group *member;
- list_for_each_entry_rcu(member, &group->member_list, head.list) {
+ list_for_each_entry_rcu(member, &group->member_list, head.list,
+ srcu_read_lock_held(&tomoyo_ss)) {
if (member->head.is_deleted)
continue;
if (!tomoyo_path_matches_pattern(pathname, member->member_name))
@@ -161,7 +162,8 @@ bool tomoyo_number_matches_group(const unsigned long min,
struct tomoyo_number_group *member;
bool matched = false;
- list_for_each_entry_rcu(member, &group->member_list, head.list) {
+ list_for_each_entry_rcu(member, &group->member_list, head.list,
+ srcu_read_lock_held(&tomoyo_ss)) {
if (member->head.is_deleted)
continue;
if (min > member->number.values[1] ||
@@ -191,7 +193,8 @@ bool tomoyo_address_matches_group(const bool is_ipv6, const __be32 *address,
bool matched = false;
const u8 size = is_ipv6 ? 16 : 4;
- list_for_each_entry_rcu(member, &group->member_list, head.list) {
+ list_for_each_entry_rcu(member, &group->member_list, head.list,
+ srcu_read_lock_held(&tomoyo_ss)) {
if (member->head.is_deleted)
continue;
if (member->address.is_ipv6 != is_ipv6)
diff --git a/security/tomoyo/util.c b/security/tomoyo/util.c
index 52752e1a84ed..eba0b3395851 100644
--- a/security/tomoyo/util.c
+++ b/security/tomoyo/util.c
@@ -594,7 +594,8 @@ struct tomoyo_domain_info *tomoyo_find_domain(const char *domainname)
name.name = domainname;
tomoyo_fill_path_info(&name);
- list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
+ list_for_each_entry_rcu(domain, &tomoyo_domain_list, list,
+ srcu_read_lock_held(&tomoyo_ss)) {
if (!domain->is_deleted &&
!tomoyo_pathcmp(&name, domain->domainname))
return domain;
@@ -1028,7 +1029,8 @@ bool tomoyo_domain_quota_is_ok(struct tomoyo_request_info *r)
return false;
if (!domain)
return true;
- list_for_each_entry_rcu(ptr, &domain->acl_info_list, list) {
+ list_for_each_entry_rcu(ptr, &domain->acl_info_list, list,
+ srcu_read_lock_held(&tomoyo_ss)) {
u16 perm;
u8 i;