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sysctl: Create pipe-max-size converter using sysctl UINT macros 

Create a converter for the pipe-max-size proc_handler using the
SYSCTL_UINT_CONV_CUSTOM. Move SYSCTL_CONV_IDENTITY macro to the sysctl
header to make it available for pipe size validation. Keep returning
-EINVAL when (val == 0) by using a range checking converter and setting
the minimal valid value (extern1) to SYSCTL_ONE. Keep round_pipe_size by
passing it as the operation for SYSCTL_USER_TO_KERN_INT_CONV.

Signed-off-by: Joel Granados <joel.granados@kernel.org>
This commit is contained in:
Joel Granados 2025-10-14 14:21:03 +02:00
parent 4639faaa60
commit 30baaeb685
3 changed files with 7 additions and 22 deletions
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26
fs/pipe.c
View File

@ -1481,31 +1481,16 @@ static struct file_system_type pipe_fs_type = {
};
#ifdef CONFIG_SYSCTL
static int do_proc_dopipe_max_size_conv(unsigned long *lvalp,
unsigned int *valp, int write,
const struct ctl_table *table)
{
if (write) {
unsigned int val;
val = round_pipe_size(*lvalp);
if (val == 0)
return -EINVAL;
*valp = val;
} else {
unsigned int val = *valp;
*lvalp = (unsigned long) val;
}
return 0;
}
static SYSCTL_USER_TO_KERN_UINT_CONV(_pipe_maxsz, round_pipe_size)
static SYSCTL_UINT_CONV_CUSTOM(_pipe_maxsz,
sysctl_user_to_kern_uint_conv_pipe_maxsz,
sysctl_kern_to_user_uint_conv, true)
static int proc_dopipe_max_size(const struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
return do_proc_douintvec(table, write, buffer, lenp, ppos,
do_proc_dopipe_max_size_conv);
do_proc_uint_conv_pipe_maxsz);
}
static const struct ctl_table fs_pipe_sysctls[] = {
@ -1515,6 +1500,7 @@ static const struct ctl_table fs_pipe_sysctls[] = {
.maxlen = sizeof(pipe_max_size),
.mode = 0644,
.proc_handler = proc_dopipe_max_size,
.extra1 = SYSCTL_ONE,
},
{
.procname = "pipe-user-pages-hard",

1
include/linux/sysctl.h
View File

@ -59,6 +59,7 @@ extern const int sysctl_vals[];
#define SYSCTL_LONG_ONE ((void *)&sysctl_long_vals[1])
#define SYSCTL_LONG_MAX ((void *)&sysctl_long_vals[2])
#define SYSCTL_CONV_IDENTITY(val) (val)
/**
*
* "dir" originates from read_iter (dir = 0) or write_iter (dir = 1)

2
kernel/sysctl.c
View File

@ -354,8 +354,6 @@ static void proc_put_char(void **buf, size_t *size, char c)
}
}
#define SYSCTL_CONV_IDENTITY(val) val
static SYSCTL_USER_TO_KERN_INT_CONV(, SYSCTL_CONV_IDENTITY)
static SYSCTL_KERN_TO_USER_INT_CONV(, SYSCTL_CONV_IDENTITY)