sysctl: add unsigned int range support

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.

Link: http://lkml.kernel.org/r/20170519033554.18592-6-mcgrof@kernel.org
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
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: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index ee6feba8b6c0abb911333d68bf9ed229c7428b3a..8f9d564d0969f6442a04dd6f1020d529fe8487a7 100644 (file)
--- 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 80d07816def05bf0f7662c46d56387830dec3d57..225001d437ae32e5e706c87be2df1111662a398f 100644 (file)
--- 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 d12078fc215fef4a90a1e75586c53cd108b83cb7..df9f2a36788216c3e659b4bc5af7aee11377247a 100644 (file)
--- 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);