sysctl: Add optional range checking to SYSCTL_UINT_CONV_CUSTOM

Add k_ptr_range_check parameter to SYSCTL_UINT_CONV_CUSTOM macro to
enable range validation using table->extra1/extra2. Replace
do_proc_douintvec_minmax_conv with do_proc_uint_conv_minmax generated
by the updated macro.

Signed-off-by: Joel Granados <joel.granados@kernel.org>

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index fb4f4ec99811d175da6b6ccfa975c8abad4462e7..1e8d330a773de5446d85ba6961d2c2199fc524ab 100644 (file)
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -462,15 +462,6 @@ static SYSCTL_INT_CONV_CUSTOM(_ms_jiffies_minmax,
                              sysctl_user_to_kern_int_conv_ms,
                              sysctl_kern_to_user_int_conv_ms, true)
 
-#define SYSCTL_UINT_CONV_CUSTOM(name, user_to_kern, kern_to_user)      \
-int do_proc_uint_conv##name(unsigned long *u_ptr, unsigned int *k_ptr, \
-                          int dir, const struct ctl_table *tbl)        \
-{                                                                      \
-       if (SYSCTL_USER_TO_KERN(dir))                                   \
-               return user_to_kern(u_ptr, k_ptr);                      \
-       return kern_to_user(u_ptr, k_ptr);                              \
-}
-
 static int sysctl_user_to_kern_uint_conv(const unsigned long *u_ptr,
                                         unsigned int *k_ptr)
 {
@@ -488,8 +479,37 @@ static int sysctl_kern_to_user_uint_conv(unsigned long *u_ptr,
        return 0;
 }
 
+#define SYSCTL_UINT_CONV_CUSTOM(name, user_to_kern, kern_to_user,      \
+                               k_ptr_range_check)                      \
+int do_proc_uint_conv##name(unsigned long *u_ptr, unsigned int *k_ptr, \
+                          int dir, const struct ctl_table *tbl)        \
+{                                                                      \
+       if (SYSCTL_KERN_TO_USER(dir))                                   \
+               return kern_to_user(u_ptr, k_ptr);                      \
+                                                                       \
+       if (k_ptr_range_check) {                                        \
+               unsigned int tmp_k;                                     \
+               int ret;                                                \
+               if (!tbl)                                               \
+                       return -EINVAL;                                 \
+               ret = user_to_kern(u_ptr, &tmp_k);                      \
+               if (ret)                                                \
+                       return ret;                                     \
+               if ((tbl->extra1 &&                                     \
+                    *(unsigned int *)tbl->extra1 > tmp_k) ||           \
+                   (tbl->extra2 &&                                     \
+                    *(unsigned int *)tbl->extra2 < tmp_k))             \
+                       return -ERANGE;                                 \
+               WRITE_ONCE(*k_ptr, tmp_k);                              \
+       } else                                                          \
+               return user_to_kern(u_ptr, k_ptr);                      \
+       return 0;                                                       \
+}
+
 static SYSCTL_UINT_CONV_CUSTOM(, sysctl_user_to_kern_uint_conv,
-                              sysctl_kern_to_user_uint_conv)
+                              sysctl_kern_to_user_uint_conv, false)
+static SYSCTL_UINT_CONV_CUSTOM(_minmax, sysctl_user_to_kern_uint_conv,
+                              sysctl_kern_to_user_uint_conv, true)
 
 static const char proc_wspace_sep[] = { ' ', '\t', '\n' };
 
@@ -783,31 +803,6 @@ int proc_dointvec_minmax(const struct ctl_table *table, int dir,
                                do_proc_int_conv_minmax);
 }
 
-static int do_proc_douintvec_minmax_conv(unsigned long *u_ptr,
-                                        unsigned int *k_ptr, int dir,
-                                        const struct ctl_table *table)
-{
-       int ret;
-       unsigned int tmp, *min, *max;
-       /* When writing to the kernel use a temp local uint for bounds-checking */
-       unsigned int *up = SYSCTL_USER_TO_KERN(dir) ? &tmp : k_ptr;
-
-       ret = do_proc_uint_conv(u_ptr, up, dir, table);
-       if (ret)
-               return ret;
-
-       if (SYSCTL_USER_TO_KERN(dir)) {
-               min = (unsigned int *) table->extra1;
-               max = (unsigned int *) table->extra2;
-               if ((min && *min > tmp) || (max && *max < tmp))
-                       return -ERANGE;
-
-               WRITE_ONCE(*k_ptr, tmp);
-       }
-
-       return 0;
-}
-
 /**
  * proc_douintvec_minmax - read a vector of unsigned ints with min/max values
  * @table: the sysctl table
@@ -832,7 +827,7 @@ int proc_douintvec_minmax(const struct ctl_table *table, int dir,
                          void *buffer, size_t *lenp, loff_t *ppos)
 {
        return do_proc_douintvec(table, dir, buffer, lenp, ppos,
-                                do_proc_douintvec_minmax_conv);
+                                do_proc_uint_conv_minmax);
 }
 
 /**
@@ -876,7 +871,7 @@ int proc_dou8vec_minmax(const struct ctl_table *table, int dir,
 
        val = READ_ONCE(*data);
        res = do_proc_douintvec(&tmp, dir, buffer, lenp, ppos,
-                               do_proc_douintvec_minmax_conv);
+                               do_proc_uint_conv_minmax);
        if (res)
                return res;
        if (SYSCTL_USER_TO_KERN(dir))