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Date: Mon, 19 Feb 2018 11:53:49 -0500
From: Waiman Long <longman@...hat.com>
To: "Luis R. Rodriguez" <mcgrof@...nel.org>,
Kees Cook <keescook@...omium.org>
Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
Andrew Morton <akpm@...ux-foundation.org>,
Al Viro <viro@...iv.linux.org.uk>,
Waiman Long <longman@...hat.com>
Subject: [PATCH 1/3] sysctl: Add range clamping intvec helper functions
The current intvec range helper functions will fail with error when
users try to assign an out-of-range value.
The following new non-failing range helper functions are now added:
- proc_dointvec_clamp_minmax()
- proc_douintvec_clamp_minmax()
The new helper functions will clamp the value to within the given
min/max range without failing it.
Signed-off-by: Waiman Long <longman@...hat.com>
---
include/linux/sysctl.h | 6 ++++
kernel/sysctl.c | 97 ++++++++++++++++++++++++++++++++++++++++++++++----
2 files changed, 96 insertions(+), 7 deletions(-)
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index b769ecf..7684ea5 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -63,6 +63,12 @@ extern int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int,
void __user *, size_t *, loff_t *);
extern int proc_do_large_bitmap(struct ctl_table *, int,
void __user *, size_t *, loff_t *);
+extern int proc_dointvec_clamp_minmax(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp,
+ loff_t *ppos);
+extern int proc_douintvec_clamp_minmax(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp,
+ loff_t *ppos);
/*
* Register a set of sysctl names by calling register_sysctl_table
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index f98f28c..f86c3a7 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2500,9 +2500,15 @@ static int proc_dointvec_minmax_sysadmin(struct ctl_table *table, int write,
}
#endif
+/*
+ * The clamping flag, if set, will clamp the input value to the range
+ * specified by the given min/max values instead of returning error when
+ * out of range.
+ */
struct do_proc_dointvec_minmax_conv_param {
int *min;
int *max;
+ bool clamp;
};
static int do_proc_dointvec_minmax_conv(bool *negp, unsigned long *lvalp,
@@ -2512,9 +2518,18 @@ static int do_proc_dointvec_minmax_conv(bool *negp, unsigned long *lvalp,
struct do_proc_dointvec_minmax_conv_param *param = data;
if (write) {
int val = *negp ? -*lvalp : *lvalp;
- if ((param->min && *param->min > val) ||
- (param->max && *param->max < val))
- return -EINVAL;
+ if (param->min && *param->min > val) {
+ if (param->clamp)
+ val = *param->min;
+ else
+ return -EINVAL;
+ }
+ if (param->max && *param->max < val) {
+ if (param->clamp)
+ val = *param->max;
+ else
+ return -EINVAL;
+ }
*valp = val;
} else {
int val = *valp;
@@ -2556,9 +2571,38 @@ int proc_dointvec_minmax(struct ctl_table *table, int write,
do_proc_dointvec_minmax_conv, ¶m);
}
+/**
+ * proc_dointvec_clamp_minmax - read a vector of integers with min/max values
+ * @table: the sysctl table
+ * @write: %TRUE if this is a write to the sysctl file
+ * @buffer: the user buffer
+ * @lenp: the size of the user buffer
+ * @ppos: file position
+ *
+ * Reads/writes up to table->maxlen/sizeof(unsigned int) integer
+ * values from/to the user buffer, treated as an ASCII string.
+ *
+ * This routine will clamp the values to within the range specified by
+ * table->extra1 (min) and table->extra2 (max).
+ *
+ * Returns 0 on success.
+ */
+int proc_dointvec_clamp_minmax(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ struct do_proc_dointvec_minmax_conv_param param = {
+ .min = (int *) table->extra1,
+ .max = (int *) table->extra2,
+ .clamp = true,
+ };
+ return do_proc_dointvec(table, write, buffer, lenp, ppos,
+ do_proc_dointvec_minmax_conv, ¶m);
+}
+
struct do_proc_douintvec_minmax_conv_param {
unsigned int *min;
unsigned int *max;
+ bool clamp;
};
static int do_proc_douintvec_minmax_conv(unsigned long *lvalp,
@@ -2573,10 +2617,18 @@ static int do_proc_douintvec_minmax_conv(unsigned long *lvalp,
if (*lvalp > UINT_MAX)
return -EINVAL;
- if ((param->min && *param->min > val) ||
- (param->max && *param->max < val))
- return -ERANGE;
-
+ if (param->min && *param->min > val) {
+ if (param->clamp)
+ val = *param->min;
+ else
+ return -ERANGE;
+ }
+ if (param->max && *param->max < val) {
+ if (param->clamp)
+ val = *param->max;
+ else
+ return -ERANGE;
+ }
*valp = val;
} else {
unsigned int val = *valp;
@@ -2616,6 +2668,37 @@ int proc_douintvec_minmax(struct ctl_table *table, int write,
do_proc_douintvec_minmax_conv, ¶m);
}
+/**
+ * proc_douintvec_clamp_minmax - read a vector of uints with min/max values
+ * @table: the sysctl table
+ * @write: %TRUE if this is a write to the sysctl file
+ * @buffer: the user buffer
+ * @lenp: the size of the user buffer
+ * @ppos: file position
+ *
+ * Reads/writes up to table->maxlen/sizeof(unsigned int) unsigned integer
+ * values from/to the user buffer, treated as an ASCII string. Negative
+ * strings are not allowed.
+ *
+ * This routine will clamp the values to within the range specified by
+ * table->extra1 (min) and table->extra2 (max). There is a final sanity
+ * check for UINT_MAX to avoid having to support wrap around uses from
+ * userspace.
+ *
+ * Returns 0 on success.
+ */
+int proc_douintvec_clamp_minmax(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ struct do_proc_douintvec_minmax_conv_param param = {
+ .min = (unsigned int *) table->extra1,
+ .max = (unsigned int *) table->extra2,
+ .clamp = true,
+ };
+ return do_proc_douintvec(table, write, buffer, lenp, ppos,
+ do_proc_douintvec_minmax_conv, ¶m);
+}
+
static int do_proc_dopipe_max_size_conv(unsigned long *lvalp,
unsigned int *valp,
int write, void *data)
--
1.8.3.1
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