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Subject[net-next PATCH v3 1/3] sysctl: refactor integer handling proc code
Date
As we are about to add another integer handling proc function a little
bit of cleanup is in order: add a few helper functions to improve code
readability and decrease code duplication.

In the process a bug is fixed as well: if the user specifies a number
with more then 20 digits it will be interpreted as two integers
(e.g. 10000...13 will be interpreted as 100.... and 13).

Signed-off-by: Octavian Purdila <opurdila@ixiacom.com>
Cc: WANG Cong <amwang@redhat.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
---
kernel/sysctl.c | 298 +++++++++++++++++++++++++++----------------------------
1 files changed, 144 insertions(+), 154 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 8a68b24..b0f9618 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2039,8 +2039,98 @@ int proc_dostring(struct ctl_table *table, int write,
buffer, lenp, ppos);
}

+static int proc_skip_wspace(char __user **buf, size_t *size)
+{
+ char c;
+
+ while (*size) {
+ if (get_user(c, *buf))
+ return -EFAULT;
+ if (!isspace(c))
+ break;
+ (*size)--; (*buf)++;
+ }
+
+ return 0;
+}
+
+#define TMPBUFLEN 22
+static int proc_get_next_ulong(char __user **buf, size_t *size,
+ unsigned long *val, bool *neg)
+{
+ int len;
+ char *p, tmp[TMPBUFLEN];
+ int err;
+
+ err = proc_skip_wspace(buf, size);
+ if (err)
+ return err;
+ if (!*size)
+ return -EINVAL;
+
+ len = *size;
+ if (len > TMPBUFLEN-1)
+ len = TMPBUFLEN-1;
+
+ if (copy_from_user(tmp, *buf, len))
+ return -EFAULT;
+
+ tmp[len] = 0;
+ p = tmp;
+ if (*p == '-' && *size > 1) {
+ *neg = 1;
+ p++;
+ } else
+ *neg = 0;
+ if (*p < '0' || *p > '9')
+ return -EINVAL;
+
+ *val = simple_strtoul(p, &p, 0);
+
+ len = p - tmp;
+ if (((len < *size) && *p && !isspace(*p)) ||
+ /* We don't know if the next char is whitespace thus we may accept
+ * invalid integers (e.g. 1234...a) or two integers instead of one
+ * (e.g. 123...1). So lets not allow such large numbers. */
+ len == TMPBUFLEN - 1)
+ return -EINVAL;

-static int do_proc_dointvec_conv(int *negp, unsigned long *lvalp,
+ *buf += len; *size -= len;
+
+ return 0;
+}
+
+static int proc_put_ulong(char __user **buf, size_t *size, unsigned long val,
+ bool neg, bool first)
+{
+ int len;
+ char tmp[TMPBUFLEN], *p = tmp;
+
+ if (!first)
+ *p++ = '\t';
+ sprintf(p, "%s%lu", neg ? "-" : "", val);
+ len = strlen(tmp);
+ if (len > *size)
+ len = *size;
+ if (copy_to_user(*buf, tmp, len))
+ return -EFAULT;
+ *size -= len;
+ *buf += len;
+ return 0;
+}
+#undef TMPBUFLEN
+
+static int proc_put_newline(char __user **buf, size_t *size)
+{
+ if (*size) {
+ if (put_user('\n', *buf))
+ return -EFAULT;
+ (*size)--, (*buf)++;
+ }
+ return 0;
+}
+
+static int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp,
int *valp,
int write, void *data)
{
@@ -2049,7 +2139,7 @@ static int do_proc_dointvec_conv(int *negp, unsigned long *lvalp,
} else {
int val = *valp;
if (val < 0) {
- *negp = -1;
+ *negp = 1;
*lvalp = (unsigned long)-val;
} else {
*negp = 0;
@@ -2060,19 +2150,15 @@ static int do_proc_dointvec_conv(int *negp, unsigned long *lvalp,
}

static int __do_proc_dointvec(void *tbl_data, struct ctl_table *table,
- int write, void __user *buffer,
+ int write, void __user *_buffer,
size_t *lenp, loff_t *ppos,
- int (*conv)(int *negp, unsigned long *lvalp, int *valp,
+ int (*conv)(bool *negp, unsigned long *lvalp, int *valp,
int write, void *data),
void *data)
{
-#define TMPBUFLEN 21
- int *i, vleft, first = 1, neg;
- unsigned long lval;
- size_t left, len;
-
- char buf[TMPBUFLEN], *p;
- char __user *s = buffer;
+ int *i, vleft, first = 1, err = 0;
+ size_t left;
+ char __user *buffer = (char __user *) _buffer;

if (!tbl_data || !table->maxlen || !*lenp ||
(*ppos && !write)) {
@@ -2088,88 +2174,39 @@ static int __do_proc_dointvec(void *tbl_data, struct ctl_table *table,
conv = do_proc_dointvec_conv;

for (; left && vleft--; i++, first=0) {
- if (write) {
- while (left) {
- char c;
- if (get_user(c, s))
- return -EFAULT;
- if (!isspace(c))
- break;
- left--;
- s++;
- }
- if (!left)
- break;
- neg = 0;
- len = left;
- if (len > sizeof(buf) - 1)
- len = sizeof(buf) - 1;
- if (copy_from_user(buf, s, len))
- return -EFAULT;
- buf[len] = 0;
- p = buf;
- if (*p == '-' && left > 1) {
- neg = 1;
- p++;
- }
- if (*p < '0' || *p > '9')
- break;
-
- lval = simple_strtoul(p, &p, 0);
+ unsigned long lval;
+ bool neg;

- len = p-buf;
- if ((len < left) && *p && !isspace(*p))
+ if (write) {
+ err = proc_get_next_ulong(&buffer, &left, &lval, &neg);
+ if (err)
break;
- s += len;
- left -= len;
-
if (conv(&neg, &lval, i, 1, data))
break;
} else {
- p = buf;
- if (!first)
- *p++ = '\t';
-
if (conv(&neg, &lval, i, 0, data))
break;
-
- sprintf(p, "%s%lu", neg ? "-" : "", lval);
- len = strlen(buf);
- if (len > left)
- len = left;
- if(copy_to_user(s, buf, len))
- return -EFAULT;
- left -= len;
- s += len;
- }
- }
-
- if (!write && !first && left) {
- if(put_user('\n', s))
- return -EFAULT;
- left--, s++;
- }
- if (write) {
- while (left) {
- char c;
- if (get_user(c, s++))
- return -EFAULT;
- if (!isspace(c))
+ err = proc_put_ulong(&buffer, &left, lval, neg, first);
+ if (err)
break;
- left--;
}
}
- if (write && first)
- return -EINVAL;
+
+ if (!write && !first && left && !err)
+ err = proc_put_newline(&buffer, &left);
+ if (write && !err)
+ err = proc_skip_wspace(&buffer, &left);
+ if (err == -EFAULT /* do we really need to check for -EFAULT? */ ||
+ (write && first))
+ return err ? : -EINVAL;
*lenp -= left;
*ppos += *lenp;
return 0;
-#undef TMPBUFLEN
}

static int do_proc_dointvec(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos,
- int (*conv)(int *negp, unsigned long *lvalp, int *valp,
+ int (*conv)(bool *negp, unsigned long *lvalp, int *valp,
int write, void *data),
void *data)
{
@@ -2237,8 +2274,8 @@ struct do_proc_dointvec_minmax_conv_param {
int *max;
};

-static int do_proc_dointvec_minmax_conv(int *negp, unsigned long *lvalp,
- int *valp,
+static int do_proc_dointvec_minmax_conv(bool *negp, unsigned long *lvalp,
+ int *valp,
int write, void *data)
{
struct do_proc_dointvec_minmax_conv_param *param = data;
@@ -2251,7 +2288,7 @@ static int do_proc_dointvec_minmax_conv(int *negp, unsigned long *lvalp,
} else {
int val = *valp;
if (val < 0) {
- *negp = -1;
+ *negp = 1;
*lvalp = (unsigned long)-val;
} else {
*negp = 0;
@@ -2289,17 +2326,15 @@ int proc_dointvec_minmax(struct ctl_table *table, int write,
}

static int __do_proc_doulongvec_minmax(void *data, struct ctl_table *table, int write,
- void __user *buffer,
+ void __user *_buffer,
size_t *lenp, loff_t *ppos,
unsigned long convmul,
unsigned long convdiv)
{
-#define TMPBUFLEN 21
- unsigned long *i, *min, *max, val;
- int vleft, first=1, neg;
- size_t len, left;
- char buf[TMPBUFLEN], *p;
- char __user *s = buffer;
+ unsigned long *i, *min, *max;
+ int vleft, first = 1, err = 0;
+ size_t left;
+ char __user *buffer = (char __user *) _buffer;

if (!data || !table->maxlen || !*lenp ||
(*ppos && !write)) {
@@ -2314,82 +2349,37 @@ static int __do_proc_doulongvec_minmax(void *data, struct ctl_table *table, int
left = *lenp;

for (; left && vleft--; i++, min++, max++, first=0) {
+ unsigned long val;
+
if (write) {
- while (left) {
- char c;
- if (get_user(c, s))
- return -EFAULT;
- if (!isspace(c))
- break;
- left--;
- s++;
- }
- if (!left)
- break;
- neg = 0;
- len = left;
- if (len > TMPBUFLEN-1)
- len = TMPBUFLEN-1;
- if (copy_from_user(buf, s, len))
- return -EFAULT;
- buf[len] = 0;
- p = buf;
- if (*p == '-' && left > 1) {
- neg = 1;
- p++;
- }
- if (*p < '0' || *p > '9')
- break;
- val = simple_strtoul(p, &p, 0) * convmul / convdiv ;
- len = p-buf;
- if ((len < left) && *p && !isspace(*p))
+ bool neg;
+
+ err = proc_get_next_ulong(&buffer, &left, &val, &neg);
+ if (err)
break;
if (neg)
- val = -val;
- s += len;
- left -= len;
-
- if(neg)
continue;
if ((min && val < *min) || (max && val > *max))
continue;
*i = val;
} else {
- p = buf;
- if (!first)
- *p++ = '\t';
- sprintf(p, "%lu", convdiv * (*i) / convmul);
- len = strlen(buf);
- if (len > left)
- len = left;
- if(copy_to_user(s, buf, len))
- return -EFAULT;
- left -= len;
- s += len;
- }
- }
-
- if (!write && !first && left) {
- if(put_user('\n', s))
- return -EFAULT;
- left--, s++;
- }
- if (write) {
- while (left) {
- char c;
- if (get_user(c, s++))
- return -EFAULT;
- if (!isspace(c))
+ val = convdiv * (*i) / convmul;
+ err = proc_put_ulong(&buffer, &left, val, 0, first);
+ if (err)
break;
- left--;
}
}
- if (write && first)
- return -EINVAL;
+
+ if (!write && !first && left && !err)
+ err = proc_put_newline(&buffer, &left);
+ if (write && !err)
+ err = proc_skip_wspace(&buffer, &left);
+ if (err == -EFAULT /* do we really need to check for -EFAULT? */ ||
+ (write && first))
+ return err ? : -EINVAL;
*lenp -= left;
*ppos += *lenp;
return 0;
-#undef TMPBUFLEN
}

static int do_proc_doulongvec_minmax(struct ctl_table *table, int write,
@@ -2450,7 +2440,7 @@ int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int write,
}


-static int do_proc_dointvec_jiffies_conv(int *negp, unsigned long *lvalp,
+static int do_proc_dointvec_jiffies_conv(bool *negp, unsigned long *lvalp,
int *valp,
int write, void *data)
{
@@ -2462,7 +2452,7 @@ static int do_proc_dointvec_jiffies_conv(int *negp, unsigned long *lvalp,
int val = *valp;
unsigned long lval;
if (val < 0) {
- *negp = -1;
+ *negp = 1;
lval = (unsigned long)-val;
} else {
*negp = 0;
@@ -2473,7 +2463,7 @@ static int do_proc_dointvec_jiffies_conv(int *negp, unsigned long *lvalp,
return 0;
}

-static int do_proc_dointvec_userhz_jiffies_conv(int *negp, unsigned long *lvalp,
+static int do_proc_dointvec_userhz_jiffies_conv(bool *negp, unsigned long *lvalp,
int *valp,
int write, void *data)
{
@@ -2485,7 +2475,7 @@ static int do_proc_dointvec_userhz_jiffies_conv(int *negp, unsigned long *lvalp,
int val = *valp;
unsigned long lval;
if (val < 0) {
- *negp = -1;
+ *negp = 1;
lval = (unsigned long)-val;
} else {
*negp = 0;
@@ -2496,7 +2486,7 @@ static int do_proc_dointvec_userhz_jiffies_conv(int *negp, unsigned long *lvalp,
return 0;
}

-static int do_proc_dointvec_ms_jiffies_conv(int *negp, unsigned long *lvalp,
+static int do_proc_dointvec_ms_jiffies_conv(bool *negp, unsigned long *lvalp,
int *valp,
int write, void *data)
{
@@ -2506,7 +2496,7 @@ static int do_proc_dointvec_ms_jiffies_conv(int *negp, unsigned long *lvalp,
int val = *valp;
unsigned long lval;
if (val < 0) {
- *negp = -1;
+ *negp = 1;
lval = (unsigned long)-val;
} else {
*negp = 0;
--
1.5.6.5


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