[PATCH AUTOSEL 4.19 19/26] tomoyo: ignore data race while checking quota

[PATCH AUTOSEL 4.19 19/26] tomoyo: ignore data race while checking quota

[Sasha Levin]

From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

[ Upstream commit 5797e861e402fff2bedce4ec8b7c89f4248b6073 ]

syzbot is reporting that tomoyo's quota check is racy [1]. But this check
is tolerant of some degree of inaccuracy. Thus, teach KCSAN to ignore
this data race.

[1] https://syzkaller.appspot.com/bug?id=999533deec7ba6337f8aa25d8bd1a4d5f7e50476

Reported-by: syzbot <syzbot+0789a72b46fd91431bd8@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 security/tomoyo/file.c    | 16 ++++++++--------
 security/tomoyo/network.c |  8 ++++----
 security/tomoyo/util.c    | 24 ++++++++++++------------
 3 files changed, 24 insertions(+), 24 deletions(-)

diff --git a/security/tomoyo/file.c b/security/tomoyo/file.c
index 2a374b4da8f5c..cbe0dc87bb919 100644
--- a/security/tomoyo/file.c
+++ b/security/tomoyo/file.c
@@ -356,13 +356,13 @@ static bool tomoyo_merge_path_acl(struct tomoyo_acl_info *a,
 {
 	u16 * const a_perm = &container_of(a, struct tomoyo_path_acl, head)
 		->perm;
-	u16 perm = *a_perm;
+	u16 perm = READ_ONCE(*a_perm);
 	const u16 b_perm = container_of(b, struct tomoyo_path_acl, head)->perm;
 	if (is_delete)
 		perm &= ~b_perm;
 	else
 		perm |= b_perm;
-	*a_perm = perm;
+	WRITE_ONCE(*a_perm, perm);
 	return !perm;
 }
 
@@ -428,14 +428,14 @@ static bool tomoyo_merge_mkdev_acl(struct tomoyo_acl_info *a,
 {
 	u8 *const a_perm = &container_of(a, struct tomoyo_mkdev_acl,
 					 head)->perm;
-	u8 perm = *a_perm;
+	u8 perm = READ_ONCE(*a_perm);
 	const u8 b_perm = container_of(b, struct tomoyo_mkdev_acl, head)
 		->perm;
 	if (is_delete)
 		perm &= ~b_perm;
 	else
 		perm |= b_perm;
-	*a_perm = perm;
+	WRITE_ONCE(*a_perm, perm);
 	return !perm;
 }
 
@@ -505,13 +505,13 @@ static bool tomoyo_merge_path2_acl(struct tomoyo_acl_info *a,
 {
 	u8 * const a_perm = &container_of(a, struct tomoyo_path2_acl, head)
 		->perm;
-	u8 perm = *a_perm;
+	u8 perm = READ_ONCE(*a_perm);
 	const u8 b_perm = container_of(b, struct tomoyo_path2_acl, head)->perm;
 	if (is_delete)
 		perm &= ~b_perm;
 	else
 		perm |= b_perm;
-	*a_perm = perm;
+	WRITE_ONCE(*a_perm, perm);
 	return !perm;
 }
 
@@ -640,14 +640,14 @@ static bool tomoyo_merge_path_number_acl(struct tomoyo_acl_info *a,
 {
 	u8 * const a_perm = &container_of(a, struct tomoyo_path_number_acl,
 					  head)->perm;
-	u8 perm = *a_perm;
+	u8 perm = READ_ONCE(*a_perm);
 	const u8 b_perm = container_of(b, struct tomoyo_path_number_acl, head)
 		->perm;
 	if (is_delete)
 		perm &= ~b_perm;
 	else
 		perm |= b_perm;
-	*a_perm = perm;
+	WRITE_ONCE(*a_perm, perm);
 	return !perm;
 }
 
diff --git a/security/tomoyo/network.c b/security/tomoyo/network.c
index 9094f4b3b367b..2ea0da6e5180f 100644
--- a/security/tomoyo/network.c
+++ b/security/tomoyo/network.c
@@ -233,14 +233,14 @@ static bool tomoyo_merge_inet_acl(struct tomoyo_acl_info *a,
 {
 	u8 * const a_perm =
 		&container_of(a, struct tomoyo_inet_acl, head)->perm;
-	u8 perm = *a_perm;
+	u8 perm = READ_ONCE(*a_perm);
 	const u8 b_perm = container_of(b, struct tomoyo_inet_acl, head)->perm;
 
 	if (is_delete)
 		perm &= ~b_perm;
 	else
 		perm |= b_perm;
-	*a_perm = perm;
+	WRITE_ONCE(*a_perm, perm);
 	return !perm;
 }
 
@@ -259,14 +259,14 @@ static bool tomoyo_merge_unix_acl(struct tomoyo_acl_info *a,
 {
 	u8 * const a_perm =
 		&container_of(a, struct tomoyo_unix_acl, head)->perm;
-	u8 perm = *a_perm;
+	u8 perm = READ_ONCE(*a_perm);
 	const u8 b_perm = container_of(b, struct tomoyo_unix_acl, head)->perm;
 
 	if (is_delete)
 		perm &= ~b_perm;
 	else
 		perm |= b_perm;
-	*a_perm = perm;
+	WRITE_ONCE(*a_perm, perm);
 	return !perm;
 }
 
diff --git a/security/tomoyo/util.c b/security/tomoyo/util.c
index d3d9d9f1edb04..16d488f963b12 100644
--- a/security/tomoyo/util.c
+++ b/security/tomoyo/util.c
@@ -1020,30 +1020,30 @@ bool tomoyo_domain_quota_is_ok(struct tomoyo_request_info *r)
 		u8 i;
 		if (ptr->is_deleted)
 			continue;
+		/*
+		 * Reading perm bitmap might race with tomoyo_merge_*() because
+		 * caller does not hold tomoyo_policy_lock mutex. But exceeding
+		 * max_learning_entry parameter by a few entries does not harm.
+		 */
 		switch (ptr->type) {
 		case TOMOYO_TYPE_PATH_ACL:
-			perm = container_of(ptr, struct tomoyo_path_acl, head)
-				->perm;
+			data_race(perm = container_of(ptr, struct tomoyo_path_acl, head)->perm);
 			break;
 		case TOMOYO_TYPE_PATH2_ACL:
-			perm = container_of(ptr, struct tomoyo_path2_acl, head)
-				->perm;
+			data_race(perm = container_of(ptr, struct tomoyo_path2_acl, head)->perm);
 			break;
 		case TOMOYO_TYPE_PATH_NUMBER_ACL:
-			perm = container_of(ptr, struct tomoyo_path_number_acl,
-					    head)->perm;
+			data_race(perm = container_of(ptr, struct tomoyo_path_number_acl, head)
+				  ->perm);
 			break;
 		case TOMOYO_TYPE_MKDEV_ACL:
-			perm = container_of(ptr, struct tomoyo_mkdev_acl,
-					    head)->perm;
+			data_race(perm = container_of(ptr, struct tomoyo_mkdev_acl, head)->perm);
 			break;
 		case TOMOYO_TYPE_INET_ACL:
-			perm = container_of(ptr, struct tomoyo_inet_acl,
-					    head)->perm;
+			data_race(perm = container_of(ptr, struct tomoyo_inet_acl, head)->perm);
 			break;
 		case TOMOYO_TYPE_UNIX_ACL:
-			perm = container_of(ptr, struct tomoyo_unix_acl,
-					    head)->perm;
+			data_race(perm = container_of(ptr, struct tomoyo_unix_acl, head)->perm);
 			break;
 		case TOMOYO_TYPE_MANUAL_TASK_ACL:
 			perm = 0;
-- 
2.27.0

[PATCH AUTOSEL 4.19 20/26] smackfs: restrict bytes count in smackfs write functions

[Sasha Levin]

From: Sabyrzhan Tasbolatov <snovitoll@gmail.com>

[ Upstream commit 7ef4c19d245f3dc233fd4be5acea436edd1d83d8 ]

syzbot found WARNINGs in several smackfs write operations where
bytes count is passed to memdup_user_nul which exceeds
GFP MAX_ORDER. Check count size if bigger than PAGE_SIZE.

Per smackfs doc, smk_write_net4addr accepts any label or -CIPSO,
smk_write_net6addr accepts any label or -DELETE. I couldn't find
any general rule for other label lengths except SMK_LABELLEN,
SMK_LONGLABEL, SMK_CIPSOMAX which are documented.

Let's constrain, in general, smackfs label lengths for PAGE_SIZE.
Although fuzzer crashes write to smackfs/netlabel on 0x400000 length.

Here is a quick way to reproduce the WARNING:
python -c "print('A' * 0x400000)" > /sys/fs/smackfs/netlabel

Reported-by: syzbot+a71a442385a0b2815497@syzkaller.appspotmail.com
Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 security/smack/smackfs.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index accd3846f1e3e..4f8c1a272df07 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -1191,7 +1191,7 @@ static ssize_t smk_write_net4addr(struct file *file, const char __user *buf,
 		return -EPERM;
 	if (*ppos != 0)
 		return -EINVAL;
-	if (count < SMK_NETLBLADDRMIN)
+	if (count < SMK_NETLBLADDRMIN || count > PAGE_SIZE - 1)
 		return -EINVAL;
 
 	data = memdup_user_nul(buf, count);
@@ -1451,7 +1451,7 @@ static ssize_t smk_write_net6addr(struct file *file, const char __user *buf,
 		return -EPERM;
 	if (*ppos != 0)
 		return -EINVAL;
-	if (count < SMK_NETLBLADDRMIN)
+	if (count < SMK_NETLBLADDRMIN || count > PAGE_SIZE - 1)
 		return -EINVAL;
 
 	data = memdup_user_nul(buf, count);
@@ -1858,6 +1858,10 @@ static ssize_t smk_write_ambient(struct file *file, const char __user *buf,
 	if (!smack_privileged(CAP_MAC_ADMIN))
 		return -EPERM;
 
+	/* Enough data must be present */
+	if (count == 0 || count > PAGE_SIZE)
+		return -EINVAL;
+
 	data = memdup_user_nul(buf, count);
 	if (IS_ERR(data))
 		return PTR_ERR(data);
@@ -2029,6 +2033,9 @@ static ssize_t smk_write_onlycap(struct file *file, const char __user *buf,
 	if (!smack_privileged(CAP_MAC_ADMIN))
 		return -EPERM;
 
+	if (count > PAGE_SIZE)
+		return -EINVAL;
+
 	data = memdup_user_nul(buf, count);
 	if (IS_ERR(data))
 		return PTR_ERR(data);
@@ -2116,6 +2123,9 @@ static ssize_t smk_write_unconfined(struct file *file, const char __user *buf,
 	if (!smack_privileged(CAP_MAC_ADMIN))
 		return -EPERM;
 
+	if (count > PAGE_SIZE)
+		return -EINVAL;
+
 	data = memdup_user_nul(buf, count);
 	if (IS_ERR(data))
 		return PTR_ERR(data);
@@ -2669,6 +2679,10 @@ static ssize_t smk_write_syslog(struct file *file, const char __user *buf,
 	if (!smack_privileged(CAP_MAC_ADMIN))
 		return -EPERM;
 
+	/* Enough data must be present */
+	if (count == 0 || count > PAGE_SIZE)
+		return -EINVAL;
+
 	data = memdup_user_nul(buf, count);
 	if (IS_ERR(data))
 		return PTR_ERR(data);
@@ -2761,10 +2775,13 @@ static ssize_t smk_write_relabel_self(struct file *file, const char __user *buf,
 		return -EPERM;
 
 	/*
+	 * No partial write.
 	 * Enough data must be present.
 	 */
 	if (*ppos != 0)
 		return -EINVAL;
+	if (count == 0 || count > PAGE_SIZE)
+		return -EINVAL;
 
 	data = memdup_user_nul(buf, count);
 	if (IS_ERR(data))
-- 
2.27.0