[PATCH] smack: simplify write handlers of sysfs entries

[Dmitry Antipov]

Use the convenient 'kstrto{u,s}32_from_user()' to simplify write
handlers of /smack/{doi,direct,mapped,logging,ptrace} sysfs entries.

Signed-off-by: Dmitry Antipov <dmantipov at yandex.ru>
---
 security/smack/smackfs.c | 81 +++++++++++-----------------------------
 1 file changed, 22 insertions(+), 59 deletions(-)

diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index 6e62dcb36f74..f60d5469043e 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -1598,24 +1598,17 @@ static ssize_t smk_read_doi(struct file *filp, char __user *buf,
 static ssize_t smk_write_doi(struct file *file, const char __user *buf,
 			     size_t count, loff_t *ppos)
 {
-	char temp[80];
-	unsigned long u;
+	int ret;
+	u32 u;
 
 	if (!smack_privileged(CAP_MAC_ADMIN))
 		return -EPERM;
 
-	if (count >= sizeof(temp) || count == 0)
-		return -EINVAL;
-
-	if (copy_from_user(temp, buf, count) != 0)
-		return -EFAULT;
-
-	temp[count] = '\0';
+	ret = kstrtou32_from_user(buf, count, 10, &u);
+	if (unlikely(ret))
+		return ret;
 
-	if (kstrtoul(temp, 10, &u))
-		return -EINVAL;
-
-	if (u == CIPSO_V4_DOI_UNKNOWN || u > U32_MAX)
+	if (u == CIPSO_V4_DOI_UNKNOWN)
 		return -EINVAL;
 
 	return smk_cipso_doi(u, GFP_KERNEL) ? : count;
@@ -1664,22 +1657,14 @@ static ssize_t smk_write_direct(struct file *file, const char __user *buf,
 				size_t count, loff_t *ppos)
 {
 	struct smack_known *skp;
-	char temp[80];
-	int i;
+	int i, ret;
 
 	if (!smack_privileged(CAP_MAC_ADMIN))
 		return -EPERM;
 
-	if (count >= sizeof(temp) || count == 0)
-		return -EINVAL;
-
-	if (copy_from_user(temp, buf, count) != 0)
-		return -EFAULT;
-
-	temp[count] = '\0';
-
-	if (sscanf(temp, "%d", &i) != 1)
-		return -EINVAL;
+	ret = kstrtos32_from_user(buf, count, 10, &i);
+	if (unlikely(ret))
+		return ret;
 
 	/*
 	 * Don't do anything if the value hasn't actually changed.
@@ -1742,22 +1727,14 @@ static ssize_t smk_write_mapped(struct file *file, const char __user *buf,
 				size_t count, loff_t *ppos)
 {
 	struct smack_known *skp;
-	char temp[80];
-	int i;
+	int i, ret;
 
 	if (!smack_privileged(CAP_MAC_ADMIN))
 		return -EPERM;
 
-	if (count >= sizeof(temp) || count == 0)
-		return -EINVAL;
-
-	if (copy_from_user(temp, buf, count) != 0)
-		return -EFAULT;
-
-	temp[count] = '\0';
-
-	if (sscanf(temp, "%d", &i) != 1)
-		return -EINVAL;
+	ret = kstrtos32_from_user(buf, count, 10, &i);
+	if (unlikely(ret))
+		return ret;
 
 	/*
 	 * Don't do anything if the value hasn't actually changed.
@@ -2179,22 +2156,15 @@ static ssize_t smk_read_logging(struct file *filp, char __user *buf,
 static ssize_t smk_write_logging(struct file *file, const char __user *buf,
 				size_t count, loff_t *ppos)
 {
-	char temp[32];
-	int i;
+	int i, ret;
 
 	if (!smack_privileged(CAP_MAC_ADMIN))
 		return -EPERM;
 
-	if (count >= sizeof(temp) || count == 0)
-		return -EINVAL;
-
-	if (copy_from_user(temp, buf, count) != 0)
-		return -EFAULT;
+	ret = kstrtos32_from_user(buf, count, 10, &i);
+	if (unlikely(ret))
+		return ret;
 
-	temp[count] = '\0';
-
-	if (sscanf(temp, "%d", &i) != 1)
-		return -EINVAL;
 	if (i < 0 || i > 3)
 		return -EINVAL;
 	log_policy = i;
@@ -2838,22 +2808,15 @@ static ssize_t smk_read_ptrace(struct file *filp, char __user *buf,
 static ssize_t smk_write_ptrace(struct file *file, const char __user *buf,
 				size_t count, loff_t *ppos)
 {
-	char temp[32];
-	int i;
+	int i, ret;
 
 	if (!smack_privileged(CAP_MAC_ADMIN))
 		return -EPERM;
 
-	if (*ppos != 0 || count >= sizeof(temp) || count == 0)
-		return -EINVAL;
-
-	if (copy_from_user(temp, buf, count) != 0)
-		return -EFAULT;
+	ret = kstrtos32_from_user(buf, count, 10, &i);
+	if (unlikely(ret))
+		return ret;
 
-	temp[count] = '\0';
-
-	if (sscanf(temp, "%d", &i) != 1)
-		return -EINVAL;
 	if (i < SMACK_PTRACE_DEFAULT || i > SMACK_PTRACE_MAX)
 		return -EINVAL;
 	smack_ptrace_rule = i;
-- 
2.53.0