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sysctl: Split data conversion and file position handling

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Apply the conversions to the data in a new helper function
(apply_conv_on_vec) while file position handling and argument validation
stay in the original function. Rename function to proc_vec (from
do_proc_vec). This is a prep commit to isolate the logic that needs to
change to prevent partial sysctl vector writes. No functional change
intended

Reviewed-by: Bradley Morgan <include@grrlz.net>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
This commit is contained in:
Joel Granados 2026-08-10 11:51:27 +02:00
parent df2908090c
commit 2bfbb09b50
1 changed files with 125 additions and 84 deletions
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209
kernel/sysctl.c
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@ -595,7 +595,7 @@ static int do_proc_int_conv_minmax(bool *negp, unsigned long *u_ptr, int *k_ptr,
static const char proc_wspace_sep[] = { ' ', '\t', '\n' };
/*
* Element type processed by do_proc_vec(). The tag selects the element size
* Element type processed by proc_vec(). The tag selects the element size
* and signedness, and it selects which member of union proc_vec_conv is live.
*/
enum proc_vec_type {
@ -605,7 +605,7 @@ enum proc_vec_type {
};
/*
* Converter passed to do_proc_vec(). Only the member matching the
* Converter passed to proc_vec(). Only the member matching the
* enum proc_vec_type tag is ever read, so every dispatch stays fully typed and
* no void * converter pointer is needed.
*/
@ -637,33 +637,106 @@ static int proc_vec_conv(enum proc_vec_type type, union proc_vec_conv conv,
return -EINVAL;
}
/*
* Read/write a vector of @type elements. The element size and signedness are
* derived from @type, so a single runtime function replaces the per-type
* variants. table->data is walked as raw bytes (@i) advanced by @size; the
* converter performs the actual typed load/store.
/**
* apply_conv_on_vec - Apply converter function on data vector
*
* @conv: The converter to be applied
* @table: The sysctl table
* @data_type: Type used in converter appliation (INT, UINT or ULONG)
* @data_size: Number of data elements.
* @conv_dir: %TRUE if this is a write to the sysctl file
* @buf_nbyte: Number of bytes for buf
* @buf: The user buffer
* @buf_left_final: Number of outstanding (non converted) bytes.
*
* Element signedness is derived from @data_type. table->data is walked
* as raw bytes (@data) advanced by @data_size; the converter performs
* the actual typed load/store. Sets buf_left_final to the number of
* bytes that where left outstanding after conversion. Can be > 0.
*
* Returns: %0 on success. Non-zero on error.
*/
static int do_proc_vec(const struct ctl_table *table, int dir,
void *buffer, size_t *lenp, loff_t *ppos,
enum proc_vec_type type, union proc_vec_conv conv)
static int apply_conv_on_vec(const union proc_vec_conv conv,
const struct ctl_table *table,
const enum proc_vec_type data_type,
const size_t data_size, const int conv_dir,
const size_t buf_nbyte, void *buf,
size_t *buf_left_final)
{
int vleft, first = 1, err = 0;
size_t left, size;
bool is_unsigned;
char *i, *p;
int vec_left, first = 1, err = 0;
size_t buf_left;
char *data, *p;
bool is_unsigned = data_type == PROC_VEC_UINT || data_type == PROC_VEC_ULONG;
data = table->data;
vec_left = table->maxlen / data_size;
buf_left = buf_nbyte;
if (SYSCTL_USER_TO_KERN(conv_dir)) {
if (buf_left > PAGE_SIZE - 1)
buf_left = PAGE_SIZE - 1;
p = buf;
}
for (; buf_left && vec_left--; data += data_size, first = 0) {
unsigned long lval;
bool neg = false;
if (SYSCTL_USER_TO_KERN(conv_dir)) {
proc_skip_spaces(&p, &buf_left);
if (!buf_left)
break;
err = proc_get_long(&p, &buf_left, &lval, &neg,
proc_wspace_sep,
sizeof(proc_wspace_sep), NULL);
if (!err && neg && is_unsigned)
err = -EINVAL;
if (err)
break;
if (proc_vec_conv(data_type, conv, &neg, &lval, data, conv_dir, table)) {
err = -EINVAL;
break;
}
} else {
if (proc_vec_conv(data_type, conv, &neg, &lval, data, conv_dir, table)) {
err = -EINVAL;
break;
}
if (!first)
proc_put_char(&buf, &buf_left, '\t');
proc_put_long(&buf, &buf_left, lval, neg);
}
}
if (SYSCTL_KERN_TO_USER(conv_dir) && !first && buf_left && !err)
proc_put_char(&buf, &buf_left, '\n');
if (SYSCTL_USER_TO_KERN(conv_dir) && !err && buf_left)
proc_skip_spaces(&p, &buf_left);
if (SYSCTL_USER_TO_KERN(conv_dir) && first)
return err ? : -EINVAL;
*buf_left_final = buf_left;
return err;
}
/* Read/write a vector of @type elements. */
static int proc_vec(const struct ctl_table *table, int dir, void *buffer,
size_t *lenp, loff_t *ppos, enum proc_vec_type type,
union proc_vec_conv conv)
{
int err = 0;
size_t data_size, left_nbyte = SIZE_MAX;
switch (type) {
case PROC_VEC_INT:
size = sizeof(int);
is_unsigned = false;
data_size = sizeof(int);
break;
case PROC_VEC_UINT:
size = sizeof(uint);
is_unsigned = true;
data_size = sizeof(uint);
break;
case PROC_VEC_ULONG:
size = sizeof(ulong);
is_unsigned = true;
data_size = sizeof(ulong);
break;
default:
return -EINVAL;
@ -675,63 +748,31 @@ static int do_proc_vec(const struct ctl_table *table, int dir,
return 0;
}
i = table->data;
vleft = table->maxlen / size;
left = *lenp;
/* uint arrays are not supported, *Do not* add support for them. */
if (type == PROC_VEC_UINT && vleft != 1)
if (type == PROC_VEC_UINT && (table->maxlen / data_size) != 1)
return -EINVAL;
if (SYSCTL_USER_TO_KERN(dir)) {
if (proc_first_pos_non_zero_ignore(ppos, table))
goto out;
if (left > PAGE_SIZE - 1)
left = PAGE_SIZE - 1;
p = buffer;
}
for (; left && vleft--; i += size, first = 0) {
unsigned long lval;
bool neg = false;
err = apply_conv_on_vec(conv, table, type, data_size, dir, *lenp, buffer,
&left_nbyte);
if (SYSCTL_USER_TO_KERN(dir)) {
proc_skip_spaces(&p, &left);
/*
* An unchanged left_nbyte signals a write with no parsed element; which
* is an error. Using SIZE_MAX to detect this error is possible because:
* 1. lenp is bounded by KMALLOC_MAX_SIZE in proc_sys_call_handler
* 2. lenp could never be SIZE_MAX as it is a "ridiculous" (exabyte) allocation.
*/
if (left_nbyte == SIZE_MAX)
return err;
if (!left)
break;
err = proc_get_long(&p, &left, &lval, &neg,
proc_wspace_sep,
sizeof(proc_wspace_sep), NULL);
if (!err && neg && is_unsigned)
err = -EINVAL;
if (err)
break;
if (proc_vec_conv(type, conv, &neg, &lval, i, dir, table)) {
err = -EINVAL;
break;
}
} else {
if (proc_vec_conv(type, conv, &neg, &lval, i, dir, table)) {
err = -EINVAL;
break;
}
if (!first)
proc_put_char(&buffer, &left, '\t');
proc_put_long(&buffer, &left, lval, neg);
}
}
if (SYSCTL_KERN_TO_USER(dir) && !first && left && !err)
proc_put_char(&buffer, &left, '\n');
if (SYSCTL_USER_TO_KERN(dir) && !err && left)
proc_skip_spaces(&p, &left);
if (SYSCTL_USER_TO_KERN(dir) && first)
return err ? : -EINVAL;
*lenp -= left;
*lenp -= left_nbyte;
out:
*ppos += *lenp;
return err;
}
@ -760,8 +801,8 @@ int proc_douintvec_conv(const struct ctl_table *table, int dir, void *buffer,
if (!conv)
conv = do_proc_uint_conv;
return do_proc_vec(table, dir, buffer, lenp, ppos, PROC_VEC_UINT,
(union proc_vec_conv){ .uint_conv = conv });
return proc_vec(table, dir, buffer, lenp, ppos, PROC_VEC_UINT,
(union proc_vec_conv){ .uint_conv = conv });
}
/**
@ -820,8 +861,8 @@ int proc_dobool(const struct ctl_table *table, int dir, void *buffer,
int proc_dointvec(const struct ctl_table *table, int dir, void *buffer,
size_t *lenp, loff_t *ppos)
{
return do_proc_vec(table, dir, buffer, lenp, ppos, PROC_VEC_INT,
(union proc_vec_conv){ .int_conv = do_proc_int_conv });
return proc_vec(table, dir, buffer, lenp, ppos, PROC_VEC_INT,
(union proc_vec_conv){ .int_conv = do_proc_int_conv });
}
/**
@ -840,8 +881,8 @@ int proc_dointvec(const struct ctl_table *table, int dir, void *buffer,
int proc_douintvec(const struct ctl_table *table, int dir, void *buffer,
size_t *lenp, loff_t *ppos)
{
return do_proc_vec(table, dir, buffer, lenp, ppos, PROC_VEC_UINT,
(union proc_vec_conv){ .uint_conv = do_proc_uint_conv });
return proc_vec(table, dir, buffer, lenp, ppos, PROC_VEC_UINT,
(union proc_vec_conv){ .uint_conv = do_proc_uint_conv });
}
/**
@ -864,8 +905,8 @@ int proc_douintvec(const struct ctl_table *table, int dir, void *buffer,
int proc_dointvec_minmax(const struct ctl_table *table, int dir,
void *buffer, size_t *lenp, loff_t *ppos)
{
return do_proc_vec(table, dir, buffer, lenp, ppos, PROC_VEC_INT,
(union proc_vec_conv){ .int_conv = do_proc_int_conv_minmax });
return proc_vec(table, dir, buffer, lenp, ppos, PROC_VEC_INT,
(union proc_vec_conv){ .int_conv = do_proc_int_conv_minmax });
}
/**
@ -891,8 +932,8 @@ int proc_dointvec_minmax(const struct ctl_table *table, int dir,
int proc_douintvec_minmax(const struct ctl_table *table, int dir,
void *buffer, size_t *lenp, loff_t *ppos)
{
return do_proc_vec(table, dir, buffer, lenp, ppos, PROC_VEC_UINT,
(union proc_vec_conv){ .uint_conv = do_proc_uint_conv_minmax });
return proc_vec(table, dir, buffer, lenp, ppos, PROC_VEC_UINT,
(union proc_vec_conv){ .uint_conv = do_proc_uint_conv_minmax });
}
/**
@ -935,8 +976,8 @@ int proc_dou8vec_minmax(const struct ctl_table *table, int dir,
tmp.extra2 = (unsigned int *) &max;
val = READ_ONCE(*data);
res = do_proc_vec(&tmp, dir, buffer, lenp, ppos, PROC_VEC_UINT,
(union proc_vec_conv){ .uint_conv = do_proc_uint_conv_minmax });
res = proc_vec(&tmp, dir, buffer, lenp, ppos, PROC_VEC_UINT,
(union proc_vec_conv){ .uint_conv = do_proc_uint_conv_minmax });
if (res)
return res;
if (SYSCTL_USER_TO_KERN(dir))
@ -1066,8 +1107,8 @@ int proc_doulongvec_conv(const struct ctl_table *table, int dir,
int (*conv)(bool *negp, ulong *u_ptr, ulong *k_ptr,
int dir, const struct ctl_table *table))
{
return do_proc_vec(table, dir, buffer, lenp, ppos, PROC_VEC_ULONG,
(union proc_vec_conv){ .ulong_conv = conv });
return proc_vec(table, dir, buffer, lenp, ppos, PROC_VEC_ULONG,
(union proc_vec_conv){ .ulong_conv = conv });
}
/**
@ -1087,10 +1128,10 @@ int proc_doulongvec_conv(const struct ctl_table *table, int dir,
* Returns: %0 on success.
*/
int proc_doulongvec_minmax(const struct ctl_table *table, int dir,
void *buffer, size_t *lenp, loff_t *ppos)
void *buffer, size_t *lenp, loff_t *ppos)
{
return do_proc_vec(table, dir, buffer, lenp, ppos, PROC_VEC_ULONG,
(union proc_vec_conv){ .ulong_conv = do_proc_ulong_conv });
return proc_vec(table, dir, buffer, lenp, ppos, PROC_VEC_ULONG,
(union proc_vec_conv){ .ulong_conv = do_proc_ulong_conv });
}
/**
@ -1114,8 +1155,8 @@ int proc_dointvec_conv(const struct ctl_table *table, int dir, void *buffer,
{
if (!conv)
conv = do_proc_int_conv;
return do_proc_vec(table, dir, buffer, lenp, ppos, PROC_VEC_INT,
(union proc_vec_conv){ .int_conv = conv });
return proc_vec(table, dir, buffer, lenp, ppos, PROC_VEC_INT,
(union proc_vec_conv){ .int_conv = conv });
}
/**