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Subject[PATCH v3 5/5] sysctl: add unsigned int range support
Date
To keep parity with regular int interfaces provide the an unsigned
int proc_douintvec_minmax() which allows you to specify a range of
allowed valid numbers.

Adding proc_douintvec_minmax_sysadmin() is easy but we can wait for
an actual user for that.

Cc: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
fs/proc/proc_sysctl.c | 4 ++-
include/linux/sysctl.h | 3 +++
kernel/sysctl.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 72 insertions(+), 1 deletion(-)

diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index ee6feba8b6c0..8f9d564d0969 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -1065,7 +1065,8 @@ static int sysctl_check_table_array(const char *path, struct ctl_table *table)
{
int err = 0;

- if (table->proc_handler == proc_douintvec) {
+ if ((table->proc_handler == proc_douintvec) ||
+ (table->proc_handler == proc_douintvec_minmax)) {
if (table->maxlen != sizeof(unsigned int))
err |= sysctl_err(path, table, "array now allowed");
}
@@ -1083,6 +1084,7 @@ static int sysctl_check_table(const char *path, struct ctl_table *table)
if ((table->proc_handler == proc_dostring) ||
(table->proc_handler == proc_dointvec) ||
(table->proc_handler == proc_douintvec) ||
+ (table->proc_handler == proc_douintvec_minmax) ||
(table->proc_handler == proc_dointvec_minmax) ||
(table->proc_handler == proc_dointvec_jiffies) ||
(table->proc_handler == proc_dointvec_userhz_jiffies) ||
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 80d07816def0..225001d437ae 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -47,6 +47,9 @@ extern int proc_douintvec(struct ctl_table *, int,
void __user *, size_t *, loff_t *);
extern int proc_dointvec_minmax(struct ctl_table *, int,
void __user *, size_t *, loff_t *);
+extern int proc_douintvec_minmax(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp,
+ loff_t *ppos);
extern int proc_dointvec_jiffies(struct ctl_table *, int,
void __user *, size_t *, loff_t *);
extern int proc_dointvec_userhz_jiffies(struct ctl_table *, int,
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index d12078fc215f..df9f2a367882 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2567,6 +2567,65 @@ int proc_dointvec_minmax(struct ctl_table *table, int write,
do_proc_dointvec_minmax_conv, &param);
}

+struct do_proc_douintvec_minmax_conv_param {
+ unsigned int *min;
+ unsigned int *max;
+};
+
+static int do_proc_douintvec_minmax_conv(unsigned long *lvalp,
+ unsigned int *valp,
+ int write, void *data)
+{
+ struct do_proc_douintvec_minmax_conv_param *param = data;
+
+ if (write) {
+ unsigned int val = *lvalp;
+
+ if ((param->min && *param->min > val) ||
+ (param->max && *param->max < val))
+ return -ERANGE;
+
+ if (*lvalp > UINT_MAX)
+ return -EINVAL;
+ *valp = val;
+ } else {
+ unsigned int val = *valp;
+ *lvalp = (unsigned long) val;
+ }
+
+ return 0;
+}
+
+/**
+ * proc_douintvec_minmax - read a vector of unsigned ints 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 ensure the values are 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_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,
+ };
+ return do_proc_douintvec(table, write, buffer, lenp, ppos,
+ do_proc_douintvec_minmax_conv, &param);
+}
+
static void validate_coredump_safety(void)
{
#ifdef CONFIG_COREDUMP
@@ -3066,6 +3125,12 @@ int proc_dointvec_minmax(struct ctl_table *table, int write,
return -ENOSYS;
}

+int proc_douintvec_minmax(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ return -ENOSYS;
+}
+
int proc_dointvec_jiffies(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
@@ -3108,6 +3173,7 @@ EXPORT_SYMBOL(proc_dointvec);
EXPORT_SYMBOL(proc_douintvec);
EXPORT_SYMBOL(proc_dointvec_jiffies);
EXPORT_SYMBOL(proc_dointvec_minmax);
+EXPORT_SYMBOL_GPL(proc_douintvec_minmax);
EXPORT_SYMBOL(proc_dointvec_userhz_jiffies);
EXPORT_SYMBOL(proc_dointvec_ms_jiffies);
EXPORT_SYMBOL(proc_dostring);
--
2.11.0
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