Ything-RepoMirrors/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-01-25 07:47:50 +00:00
Code Issues Packages Projects Releases Wiki Activity

sysctl: Create converter functions with two new macros

Browse Source 
Eight converter functions are created using two new macros
(SYSCTL_USER_TO_KERN_INT_CONV & SYSCTL_KERN_TO_USER_INT_CONV); they are
called from four pre-existing converter functions: do_proc_dointvec_conv
and do_proc_dointvec{,_userhz,_ms}_jiffies_conv. The function names
generated by the macros are differentiated by a string suffix passed as
the first macro argument.

The SYSCTL_USER_TO_KERN_INT_CONV macro first executes the u_ptr_op
operation, then checks for overflow, assigns sign (-, +) and finally
writes to the kernel var with WRITE_ONCE; it always returns an -EINVAL
when an overflow is detected. The SYSCTL_KERN_TO_USER_INT_CONV uses
READ_ONCE, casts to unsigned long, then executes the k_ptr_op before
assigning the value to the user space buffer.

The overflow check is always done against MAX_INT after applying
{k,u}_ptr_op. This approach avoids rounding or precision errors that
might occur when using the inverse operations.

Signed-off-by: Joel Granados <joel.granados@kernel.org>
This commit is contained in:
Joel Granados
2025-10-06 14:40:01 +02:00
parent 551bf18450
commit 2dc164a48e
1 changed files with 61 additions and 70 deletions
Download Patch File Download Diff File Expand all files Collapse all files

131
kernel/sysctl.c
View File

@@ -368,31 +368,65 @@ static void proc_put_char(void **buf, size_t *size, char c)
}
}
#define SYSCTL_USER_TO_KERN_INT_CONV(name, u_ptr_op) \
int sysctl_user_to_kern_int_conv##name(const bool *negp, \
const unsigned long *u_ptr,\
int *k_ptr) \
{ \
unsigned long u = u_ptr_op(*u_ptr); \
if (*negp) { \
if (u > (unsigned long) INT_MAX + 1) \
return -EINVAL; \
WRITE_ONCE(*k_ptr, -u); \
} else { \
if (u > (unsigned long) INT_MAX) \
return -EINVAL; \
WRITE_ONCE(*k_ptr, u); \
} \
return 0; \
}
#define SYSCTL_KERN_TO_USER_INT_CONV(name, k_ptr_op) \
int sysctl_kern_to_user_int_conv##name(bool *negp, \
unsigned long *u_ptr, \
const int *k_ptr) \
{ \
int val = READ_ONCE(*k_ptr); \
if (val < 0) { \
*negp = true; \
*u_ptr = -k_ptr_op((unsigned long)val); \
} else { \
*negp = false; \
*u_ptr = k_ptr_op((unsigned long)val); \
} \
return 0; \
}
#define SYSCTL_CONV_IDENTITY(val) val
#define SYSCTL_CONV_MULT_HZ(val) ((val) * HZ)
#define SYSCTL_CONV_DIV_HZ(val) ((val) / HZ)
static SYSCTL_USER_TO_KERN_INT_CONV(, SYSCTL_CONV_IDENTITY)
static SYSCTL_KERN_TO_USER_INT_CONV(, SYSCTL_CONV_IDENTITY)
static SYSCTL_USER_TO_KERN_INT_CONV(_hz, SYSCTL_CONV_MULT_HZ)
static SYSCTL_KERN_TO_USER_INT_CONV(_hz, SYSCTL_CONV_DIV_HZ)
static SYSCTL_USER_TO_KERN_INT_CONV(_userhz, clock_t_to_jiffies)
static SYSCTL_KERN_TO_USER_INT_CONV(_userhz, jiffies_to_clock_t)
static SYSCTL_USER_TO_KERN_INT_CONV(_ms, msecs_to_jiffies)
static SYSCTL_KERN_TO_USER_INT_CONV(_ms, jiffies_to_msecs)
static int do_proc_dointvec_conv(bool *negp, unsigned long *u_ptr,
int *k_ptr, int dir,
const struct ctl_table *table)
{
if (SYSCTL_USER_TO_KERN(dir)) {
if (*negp) {
if (*u_ptr > (unsigned long) INT_MAX + 1)
return -EINVAL;
WRITE_ONCE(*k_ptr, -*u_ptr);
} else {
if (*u_ptr > (unsigned long) INT_MAX)
return -EINVAL;
WRITE_ONCE(*k_ptr, *u_ptr);
}
} else {
int val = READ_ONCE(*k_ptr);
if (val < 0) {
*negp = true;
*u_ptr = -(unsigned long)val;
} else {
*negp = false;
*u_ptr = (unsigned long)val;
}
return sysctl_user_to_kern_int_conv(negp, u_ptr, k_ptr);
}
return 0;
return sysctl_kern_to_user_int_conv(negp, u_ptr, k_ptr);
}
static int do_proc_douintvec_conv(unsigned long *u_ptr,
@@ -952,31 +986,14 @@ int proc_doulongvec_ms_jiffies_minmax(const struct ctl_table *table, int dir,
lenp, ppos, HZ, 1000l);
}
static int do_proc_dointvec_jiffies_conv(bool *negp, unsigned long *u_ptr,
int *k_ptr, int dir,
const struct ctl_table *table)
{
if (SYSCTL_USER_TO_KERN(dir)) {
if (*u_ptr > INT_MAX / HZ)
return 1;
if (*negp)
WRITE_ONCE(*k_ptr, -*u_ptr * HZ);
else
WRITE_ONCE(*k_ptr, *u_ptr * HZ);
} else {
int val = READ_ONCE(*k_ptr);
unsigned long lval;
if (val < 0) {
*negp = true;
lval = -(unsigned long)val;
} else {
*negp = false;
lval = (unsigned long)val;
}
*u_ptr = lval / HZ;
return sysctl_user_to_kern_int_conv_hz(negp, u_ptr, k_ptr);
}
return 0;
return sysctl_kern_to_user_int_conv_hz(negp, u_ptr, k_ptr);
}
static int do_proc_dointvec_userhz_jiffies_conv(bool *negp, unsigned long *u_ptr,
@@ -984,22 +1001,11 @@ static int do_proc_dointvec_userhz_jiffies_conv(bool *negp, unsigned long *u_ptr
const struct ctl_table *table)
{
if (SYSCTL_USER_TO_KERN(dir)) {
if (USER_HZ < HZ && (LONG_MAX / HZ) * USER_HZ < *u_ptr)
return 1;
*k_ptr = clock_t_to_jiffies(*negp ? -*u_ptr : *u_ptr);
} else {
int val = *k_ptr;
unsigned long lval;
if (val < 0) {
*negp = true;
lval = -(unsigned long)val;
} else {
*negp = false;
lval = (unsigned long)val;
}
*u_ptr = jiffies_to_clock_t(lval);
if (USER_HZ < HZ)
return -EINVAL;
return sysctl_user_to_kern_int_conv_userhz(negp, u_ptr, k_ptr);
}
return 0;
return sysctl_kern_to_user_int_conv_userhz(negp, u_ptr, k_ptr);
}
static int do_proc_dointvec_ms_jiffies_conv(bool *negp, unsigned long *u_ptr,
@@ -1007,24 +1013,9 @@ static int do_proc_dointvec_ms_jiffies_conv(bool *negp, unsigned long *u_ptr,
const struct ctl_table *table)
{
if (SYSCTL_USER_TO_KERN(dir)) {
unsigned long jif = msecs_to_jiffies(*negp ? -*u_ptr : *u_ptr);
if (jif > INT_MAX)
return 1;
WRITE_ONCE(*k_ptr, (int)jif);
} else {
int val = READ_ONCE(*k_ptr);
unsigned long lval;
if (val < 0) {
*negp = true;
lval = -(unsigned long)val;
} else {
*negp = false;
lval = (unsigned long)val;
}
*u_ptr = jiffies_to_msecs(lval);
return sysctl_user_to_kern_int_conv_ms(negp, u_ptr, k_ptr);
}
return 0;
return sysctl_kern_to_user_int_conv_ms(negp, u_ptr, k_ptr);
}
static int do_proc_dointvec_ms_jiffies_minmax_conv(bool *negp, unsigned long *u_ptr,