From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Sabyrzhan Tasbolatov <snovitoll@gmail.com>,
syzbot+a71a442385a0b2815497@syzkaller.appspotmail.com,
Casey Schaufler <casey@schaufler-ca.com>,
Sasha Levin <sashal@kernel.org>,
linux-security-module@vger.kernel.org
Subject: [PATCH AUTOSEL 5.4 29/40] smackfs: restrict bytes count in smackfs write functions
Date: Wed, 24 Feb 2021 07:53:29 -0500 [thread overview]
Message-ID: <20210224125340.483162-29-sashal@kernel.org> (raw)
In-Reply-To: <20210224125340.483162-1-sashal@kernel.org>
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 9c4308077574c..5e75ff2e1b14f 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -1163,7 +1163,7 @@ 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);
@@ -1423,7 +1423,7 @@ 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);
@@ -1830,6 +1830,10 @@ 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);
@@ -2001,6 +2005,9 @@ 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);
@@ -2088,6 +2095,9 @@ 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);
@@ -2643,6 +2653,10 @@ 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);
@@ -2735,10 +2749,13 @@ 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
prev parent reply other threads:[~2021-02-24 13:11 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20210224125340.483162-1-sashal@kernel.org>
2021-02-24 12:53 ` [PATCH AUTOSEL 5.4 25/40] tomoyo: ignore data race while checking quota Sasha Levin
2021-02-24 12:53 ` Sasha Levin [this message]
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