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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>
This commit is contained in:
Joel Granados 2025-10-16 09:46:14 +02:00
parent 49d3288c1d
commit 0c1d2dc7cc
1 changed files with 32 additions and 37 deletions
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69
kernel/sysctl.c
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@ -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))