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products/sources/formale Sprachen/C/Linux/kernel/ (Open Source Betriebssystem Version 6.17.9^©) Datei vom 24.10.2025 mit Größe 36 kB

Quelle sysctl.c Sprache: C

// SPDX-License-Identifier: GPL-2.0-only
/*
* sysctl.c: General linux system control interface
*/

#include <linux/sysctl.h>
#include <linux/bitmap.h>
#include <linux/proc_fs.h>
#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/kobject.h>
#include <linux/highuid.h>
#include <linux/writeback.h>
#include <linux/initrd.h>
#include <linux/times.h>
#include <linux/limits.h>
#include <linux/syscalls.h>
#include <linux/capability.h>

#include "../lib/kstrtox.h"

#include <linux/uaccess.h>
#include <asm/processor.h>

/* shared constants to be used in various sysctls */
const int sysctl_vals[] = { 0, 1, 2, 3, 4, 100, 200, 1000, 3000, INT_MAX, 65535, -1 };
EXPORT_SYMBOL(sysctl_vals);

const unsigned long sysctl_long_vals[] = { 0, 1, LONG_MAX };
EXPORT_SYMBOL_GPL(sysctl_long_vals);

#if defined(CONFIG_SYSCTL)

/* Constants used for minimum and maximum */
static const int ngroups_max = NGROUPS_MAX;
static const int cap_last_cap = CAP_LAST_CAP;

#ifdef CONFIG_PROC_SYSCTL

/**
* enum sysctl_writes_mode - supported sysctl write modes
*
* @SYSCTL_WRITES_LEGACY: each write syscall must fully contain the sysctl value
* to be written, and multiple writes on the same sysctl file descriptor
* will rewrite the sysctl value, regardless of file position. No warning
* is issued when the initial position is not 0.
* @SYSCTL_WRITES_WARN: same as above but warn when the initial file position is
* not 0.
* @SYSCTL_WRITES_STRICT: writes to numeric sysctl entries must always be at
* file position 0 and the value must be fully contained in the buffer
* sent to the write syscall. If dealing with strings respect the file
* position, but restrict this to the max length of the buffer, anything
* passed the max length will be ignored. Multiple writes will append
* to the buffer.
*
* These write modes control how current file position affects the behavior of
* updating sysctl values through the proc interface on each write.
*/
enum sysctl_writes_mode {
SYSCTL_WRITES_LEGACY  = -1,
SYSCTL_WRITES_WARN  = 0,
SYSCTL_WRITES_STRICT  = 1,
};

static enum sysctl_writes_mode sysctl_writes_strict = SYSCTL_WRITES_STRICT;
#endif /* CONFIG_PROC_SYSCTL */
#endif /* CONFIG_SYSCTL */

/*
* /proc/sys support
*/

#ifdef CONFIG_PROC_SYSCTL

static int _proc_do_string(char *data, int maxlen, int write,
  char *buffer, size_t *lenp, loff_t *ppos)
{
size_t len;
char c, *p;

if (!data || !maxlen || !*lenp) {
  *lenp = 0;
  return 0;
}

if (write) {
  if (sysctl_writes_strict == SYSCTL_WRITES_STRICT) {
   /* Only continue writes not past the end of buffer. */
   len = strlen(data);
   if (len > maxlen - 1)
    len = maxlen - 1;

   if (*ppos > len)
    return 0;
   len = *ppos;
  } else {
   /* Start writing from beginning of buffer. */
   len = 0;
  }

  *ppos += *lenp;
  p = buffer;
  while ((p - buffer) < *lenp && len < maxlen - 1) {
   c = *(p++);
   if (c == 0 || c == '\n')
    break;
   data[len++] = c;
  }
  data[len] = 0;
} else {
  len = strlen(data);
  if (len > maxlen)
   len = maxlen;

  if (*ppos > len) {
   *lenp = 0;
   return 0;
  }

  data += *ppos;
  len  -= *ppos;

  if (len > *lenp)
   len = *lenp;
  if (len)
   memcpy(buffer, data, len);
  if (len < *lenp) {
   buffer[len] = '\n';
   len++;
  }
  *lenp = len;
  *ppos += len;
}
return 0;
}

static void warn_sysctl_write(const struct ctl_table *table)
{
pr_warn_once("%s wrote to %s when file position was not 0!\n"
  "This will not be supported in the future. To silence this\n"
  "warning, set kernel.sysctl_writes_strict = -1\n",
  current->comm, table->procname);
}

/**
* proc_first_pos_non_zero_ignore - check if first position is allowed
* @ppos: file position
* @table: the sysctl table
*
* Returns true if the first position is non-zero and the sysctl_writes_strict
* mode indicates this is not allowed for numeric input types. String proc
* handlers can ignore the return value.
*/
static bool proc_first_pos_non_zero_ignore(loff_t *ppos,
        const struct ctl_table *table)
{
if (!*ppos)
  return false;

switch (sysctl_writes_strict) {
case SYSCTL_WRITES_STRICT:
  return true;
case SYSCTL_WRITES_WARN:
  warn_sysctl_write(table);
  return false;
default:
  return false;
}
}

/**
* proc_dostring - read a string sysctl
* @table: the sysctl table
* @write: %TRUE if this is a write to the sysctl file
* @buffer: the user buffer
* @lenp: the size of the user buffer
* @ppos: file position
*
* Reads/writes a string from/to the user buffer. If the kernel
* buffer provided is not large enough to hold the string, the
* string is truncated. The copied string is %NULL-terminated.
* If the string is being read by the user process, it is copied
* and a newline '\n' is added. It is truncated if the buffer is
* not large enough.
*
* Returns 0 on success.
*/
int proc_dostring(const struct ctl_table *table, int write,
    void *buffer, size_t *lenp, loff_t *ppos)
{
if (write)
  proc_first_pos_non_zero_ignore(ppos, table);

return _proc_do_string(table->data, table->maxlen, write, buffer, lenp,
   ppos);
}

static void proc_skip_spaces(char **buf, size_t *size)
{
while (*size) {
  if (!isspace(**buf))
   break;
  (*size)--;
  (*buf)++;
}
}

static void proc_skip_char(char **buf, size_t *size, const char v)
{
while (*size) {
  if (**buf != v)
   break;
  (*size)--;
  (*buf)++;
}
}

/**
* strtoul_lenient - parse an ASCII formatted integer from a buffer and only
*                   fail on overflow
*
* @cp: kernel buffer containing the string to parse
* @endp: pointer to store the trailing characters
* @base: the base to use
* @res: where the parsed integer will be stored
*
* In case of success 0 is returned and @res will contain the parsed integer,
* @endp will hold any trailing characters.
* This function will fail the parse on overflow. If there wasn't an overflow
* the function will defer the decision what characters count as invalid to the
* caller.
*/
static int strtoul_lenient(const char *cp, char **endp, unsigned int base,
      unsigned long *res)
{
unsigned long long result;
unsigned int rv;

cp = _parse_integer_fixup_radix(cp, &base);
rv = _parse_integer(cp, base, &result);
if ((rv & KSTRTOX_OVERFLOW) || (result != (unsigned long)result))
  return -ERANGE;

cp += rv;

if (endp)
  *endp = (char *)cp;

*res = (unsigned long)result;
return 0;
}

#define TMPBUFLEN 22
/**
* proc_get_long - reads an ASCII formatted integer from a user buffer
*
* @buf: a kernel buffer
* @size: size of the kernel buffer
* @val: this is where the number will be stored
* @neg: set to %TRUE if number is negative
* @perm_tr: a vector which contains the allowed trailers
* @perm_tr_len: size of the perm_tr vector
* @tr: pointer to store the trailer character
*
* In case of success %0 is returned and @buf and @size are updated with
* the amount of bytes read. If @tr is non-NULL and a trailing
* character exists (size is non-zero after returning from this
* function), @tr is updated with the trailing character.
*/
static int proc_get_long(char **buf, size_t *size,
     unsigned long *val, bool *neg,
     const char *perm_tr, unsigned perm_tr_len, char *tr)
{
char *p, tmp[TMPBUFLEN];
ssize_t len = *size;

if (len <= 0)
  return -EINVAL;

if (len > TMPBUFLEN - 1)
  len = TMPBUFLEN - 1;

memcpy(tmp, *buf, len);

tmp[len] = 0;
p = tmp;
if (*p == '-' && *size > 1) {
  *neg = true;
  p++;
} else
  *neg = false;
if (!isdigit(*p))
  return -EINVAL;

if (strtoul_lenient(p, &p, 0, val))
  return -EINVAL;

len = p - tmp;

/* We don't know if the next char is whitespace thus we may accept
* invalid integers (e.g. 1234...a) or two integers instead of one
* (e.g. 123...1). So lets not allow such large numbers. */
if (len == TMPBUFLEN - 1)
  return -EINVAL;

if (len < *size && perm_tr_len && !memchr(perm_tr, *p, perm_tr_len))
  return -EINVAL;

if (tr && (len < *size))
  *tr = *p;

*buf += len;
*size -= len;

return 0;
}

/**
* proc_put_long - converts an integer to a decimal ASCII formatted string
*
* @buf: the user buffer
* @size: the size of the user buffer
* @val: the integer to be converted
* @neg: sign of the number, %TRUE for negative
*
* In case of success @buf and @size are updated with the amount of bytes
* written.
*/
static void proc_put_long(void **buf, size_t *size, unsigned long val, bool neg)
{
int len;
char tmp[TMPBUFLEN], *p = tmp;

sprintf(p, "%s%lu", neg ? "-" : "", val);
len = strlen(tmp);
if (len > *size)
  len = *size;
memcpy(*buf, tmp, len);
*size -= len;
*buf += len;
}
#undef TMPBUFLEN

static void proc_put_char(void **buf, size_t *size, char c)
{
if (*size) {
  char **buffer = (char **)buf;
  **buffer = c;

  (*size)--;
  (*buffer)++;
  *buf = *buffer;
}
}

static int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp,
     int *valp,
     int write, void *data)
{
if (write) {
  if (*negp) {
   if (*lvalp > (unsigned long) INT_MAX + 1)
    return -EINVAL;
   WRITE_ONCE(*valp, -*lvalp);
  } else {
   if (*lvalp > (unsigned long) INT_MAX)
    return -EINVAL;
   WRITE_ONCE(*valp, *lvalp);
  }
} else {
  int val = READ_ONCE(*valp);
  if (val < 0) {
   *negp = true;
   *lvalp = -(unsigned long)val;
  } else {
   *negp = false;
   *lvalp = (unsigned long)val;
  }
}
return 0;
}

static int do_proc_douintvec_conv(unsigned long *lvalp,
      unsigned int *valp,
      int write, void *data)
{
if (write) {
  if (*lvalp > UINT_MAX)
   return -EINVAL;
  WRITE_ONCE(*valp, *lvalp);
} else {
  unsigned int val = READ_ONCE(*valp);
  *lvalp = (unsigned long)val;
}
return 0;
}

static const char proc_wspace_sep[] = { ' ', '\t', '\n' };

static int __do_proc_dointvec(void *tbl_data, const struct ctl_table *table,
    int write, void *buffer,
    size_t *lenp, loff_t *ppos,
    int (*conv)(bool *negp, unsigned long *lvalp, int *valp,
         int write, void *data),
    void *data)
{
int *i, vleft, first = 1, err = 0;
size_t left;
char *p;

if (!tbl_data || !table->maxlen || !*lenp || (*ppos && !write)) {
  *lenp = 0;
  return 0;
}

i = (int *) tbl_data;
vleft = table->maxlen / sizeof(*i);
left = *lenp;

if (!conv)
  conv = do_proc_dointvec_conv;

if (write) {
  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++, first=0) {
  unsigned long lval;
  bool neg;

  if (write) {
   proc_skip_spaces(&p, &left);

   if (!left)
    break;
   err = proc_get_long(&p, &left, &lval, &neg,
          proc_wspace_sep,
          sizeof(proc_wspace_sep), NULL);
   if (err)
    break;
   if (conv(&neg, &lval, i, 1, data)) {
    err = -EINVAL;
    break;
   }
  } else {
   if (conv(&neg, &lval, i, 0, data)) {
    err = -EINVAL;
    break;
   }
   if (!first)
    proc_put_char(&buffer, &left, '\t');
   proc_put_long(&buffer, &left, lval, neg);
  }
}

if (!write && !first && left && !err)
  proc_put_char(&buffer, &left, '\n');
if (write && !err && left)
  proc_skip_spaces(&p, &left);
if (write && first)
  return err ? : -EINVAL;
*lenp -= left;
out:
*ppos += *lenp;
return err;
}

static int do_proc_dointvec(const struct ctl_table *table, int write,
    void *buffer, size_t *lenp, loff_t *ppos,
    int (*conv)(bool *negp, unsigned long *lvalp, int *valp,
         int write, void *data),
    void *data)
{
return __do_proc_dointvec(table->data, table, write,
   buffer, lenp, ppos, conv, data);
}

static int do_proc_douintvec_w(unsigned int *tbl_data,
          const struct ctl_table *table,
          void *buffer,
          size_t *lenp, loff_t *ppos,
          int (*conv)(unsigned long *lvalp,
        unsigned int *valp,
        int write, void *data),
          void *data)
{
unsigned long lval;
int err = 0;
size_t left;
bool neg;
char *p = buffer;

left = *lenp;

if (proc_first_pos_non_zero_ignore(ppos, table))
  goto bail_early;

if (left > PAGE_SIZE - 1)
  left = PAGE_SIZE - 1;

proc_skip_spaces(&p, &left);
if (!left) {
  err = -EINVAL;
  goto out_free;
}

err = proc_get_long(&p, &left, &lval, &neg,
        proc_wspace_sep,
        sizeof(proc_wspace_sep), NULL);
if (err || neg) {
  err = -EINVAL;
  goto out_free;
}

if (conv(&lval, tbl_data, 1, data)) {
  err = -EINVAL;
  goto out_free;
}

if (!err && left)
  proc_skip_spaces(&p, &left);

out_free:
if (err)
  return -EINVAL;

return 0;

/* This is in keeping with old __do_proc_dointvec() */
bail_early:
*ppos += *lenp;
return err;
}

static int do_proc_douintvec_r(unsigned int *tbl_data, void *buffer,
          size_t *lenp, loff_t *ppos,
          int (*conv)(unsigned long *lvalp,
        unsigned int *valp,
        int write, void *data),
          void *data)
{
unsigned long lval;
int err = 0;
size_t left;

left = *lenp;

if (conv(&lval, tbl_data, 0, data)) {
  err = -EINVAL;
  goto out;
}

proc_put_long(&buffer, &left, lval, false);
if (!left)
  goto out;

proc_put_char(&buffer, &left, '\n');

out:
*lenp -= left;
*ppos += *lenp;

return err;
}

static int __do_proc_douintvec(void *tbl_data, const struct ctl_table *table,
          int write, void *buffer,
          size_t *lenp, loff_t *ppos,
          int (*conv)(unsigned long *lvalp,
        unsigned int *valp,
        int write, void *data),
          void *data)
{
unsigned int *i, vleft;

if (!tbl_data || !table->maxlen || !*lenp || (*ppos && !write)) {
  *lenp = 0;
  return 0;
}

i = (unsigned int *) tbl_data;
vleft = table->maxlen / sizeof(*i);

/*
* Arrays are not supported, keep this simple. *Do not* add
* support for them.
*/
if (vleft != 1) {
  *lenp = 0;
  return -EINVAL;
}

if (!conv)
  conv = do_proc_douintvec_conv;

if (write)
  return do_proc_douintvec_w(i, table, buffer, lenp, ppos,
        conv, data);
return do_proc_douintvec_r(i, buffer, lenp, ppos, conv, data);
}

int do_proc_douintvec(const struct ctl_table *table, int write,
        void *buffer, size_t *lenp, loff_t *ppos,
        int (*conv)(unsigned long *lvalp,
      unsigned int *valp,
      int write, void *data),
        void *data)
{
return __do_proc_douintvec(table->data, table, write,
       buffer, lenp, ppos, conv, data);
}

/**
* proc_dobool - read/write a bool
* @table: the sysctl table
* @write: %TRUE if this is a write to the sysctl file
* @buffer: the user buffer
* @lenp: the size of the user buffer
* @ppos: file position
*
* Reads/writes one integer value from/to the user buffer,
* treated as an ASCII string.
*
* table->data must point to a bool variable and table->maxlen must
* be sizeof(bool).
*
* Returns 0 on success.
*/
int proc_dobool(const struct ctl_table *table, int write, void *buffer,
  size_t *lenp, loff_t *ppos)
{
struct ctl_table tmp;
bool *data = table->data;
int res, val;

/* Do not support arrays yet. */
if (table->maxlen != sizeof(bool))
  return -EINVAL;

tmp = *table;
tmp.maxlen = sizeof(val);
tmp.data = &val;

val = READ_ONCE(*data);
res = proc_dointvec(&tmp, write, buffer, lenp, ppos);
if (res)
  return res;
if (write)
  WRITE_ONCE(*data, val);
return 0;
}

/**
* proc_dointvec - read a vector of integers
* @table: the sysctl table
* @write: %TRUE if this is a write to the sysctl file
* @buffer: the user buffer
* @lenp: the size of the user buffer
* @ppos: file position
*
* Reads/writes up to table->maxlen/sizeof(unsigned int) integer
* values from/to the user buffer, treated as an ASCII string.
*
* Returns 0 on success.
*/
int proc_dointvec(const struct ctl_table *table, int write, void *buffer,
    size_t *lenp, loff_t *ppos)
{
return do_proc_dointvec(table, write, buffer, lenp, ppos, NULL, NULL);
}

/**
* proc_douintvec - read a vector of unsigned integers
* @table: the sysctl table
* @write: %TRUE if this is a write to the sysctl file
* @buffer: the user buffer
* @lenp: the size of the user buffer
* @ppos: file position
*
* Reads/writes up to table->maxlen/sizeof(unsigned int) unsigned integer
* values from/to the user buffer, treated as an ASCII string.
*
* Returns 0 on success.
*/
int proc_douintvec(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_douintvec_conv, NULL);
}

/**
* struct do_proc_dointvec_minmax_conv_param - proc_dointvec_minmax() range checking structure
* @min: pointer to minimum allowable value
* @max: pointer to maximum allowable value
*
* The do_proc_dointvec_minmax_conv_param structure provides the
* minimum and maximum values for doing range checking for those sysctl
* parameters that use the proc_dointvec_minmax() handler.
*/
struct do_proc_dointvec_minmax_conv_param {
int *min;
int *max;
};

static int do_proc_dointvec_minmax_conv(bool *negp, unsigned long *lvalp,
     int *valp,
     int write, void *data)
{
int tmp, ret;
struct do_proc_dointvec_minmax_conv_param *param = data;
/*
* If writing, first do so via a temporary local int so we can
* bounds-check it before touching *valp.
*/
int *ip = write ? &tmp : valp;

ret = do_proc_dointvec_conv(negp, lvalp, ip, write, data);
if (ret)
  return ret;

if (write) {
  if ((param->min && *param->min > tmp) ||
      (param->max && *param->max < tmp))
   return -EINVAL;
  WRITE_ONCE(*valp, tmp);
}

return 0;
}

/**
* proc_dointvec_minmax - read a vector of integers with min/max values
* @table: the sysctl table
* @write: %TRUE if this is a write to the sysctl file
* @buffer: the user buffer
* @lenp: the size of the user buffer
* @ppos: file position
*
* Reads/writes up to table->maxlen/sizeof(unsigned int) integer
* values from/to the user buffer, treated as an ASCII string.
*
* This routine will ensure the values are within the range specified by
* table->extra1 (min) and table->extra2 (max).
*
* Returns 0 on success or -EINVAL on write when the range check fails.
*/
int proc_dointvec_minmax(const struct ctl_table *table, int write,
    void *buffer, size_t *lenp, loff_t *ppos)
{
struct do_proc_dointvec_minmax_conv_param param = {
  .min = (int *) table->extra1,
  .max = (int *) table->extra2,
};
return do_proc_dointvec(table, write, buffer, lenp, ppos,
    do_proc_dointvec_minmax_conv, ¶m);
}

/**
* struct do_proc_douintvec_minmax_conv_param - proc_douintvec_minmax() range checking structure
* @min: pointer to minimum allowable value
* @max: pointer to maximum allowable value
*
* The do_proc_douintvec_minmax_conv_param structure provides the
* minimum and maximum values for doing range checking for those sysctl
* parameters that use the proc_douintvec_minmax() handler.
*/
struct do_proc_douintvec_minmax_conv_param {
unsigned int *min;
unsigned int *max;
};

static int do_proc_douintvec_minmax_conv(unsigned long *lvalp,
      unsigned int *valp,
      int write, void *data)
{
int ret;
unsigned int tmp;
struct do_proc_douintvec_minmax_conv_param *param = data;
/* write via temporary local uint for bounds-checking */
unsigned int *up = write ? &tmp : valp;

ret = do_proc_douintvec_conv(lvalp, up, write, data);
if (ret)
  return ret;

if (write) {
  if ((param->min && *param->min > tmp) ||
      (param->max && *param->max < tmp))
   return -ERANGE;

  WRITE_ONCE(*valp, tmp);
}

return 0;
}

/**
* proc_douintvec_minmax - read a vector of unsigned ints with min/max values
* @table: the sysctl table
* @write: %TRUE if this is a write to the sysctl file
* @buffer: the user buffer
* @lenp: the size of the user buffer
* @ppos: file position
*
* Reads/writes up to table->maxlen/sizeof(unsigned int) unsigned integer
* values from/to the user buffer, treated as an ASCII string. Negative
* strings are not allowed.
*
* This routine will ensure the values are within the range specified by
* table->extra1 (min) and table->extra2 (max). There is a final sanity
* check for UINT_MAX to avoid having to support wrap around uses from
* userspace.
*
* Returns 0 on success or -ERANGE on write when the range check fails.
*/
int proc_douintvec_minmax(const struct ctl_table *table, int write,
     void *buffer, size_t *lenp, loff_t *ppos)
{
struct do_proc_douintvec_minmax_conv_param param = {
  .min = (unsigned int *) table->extra1,
  .max = (unsigned int *) table->extra2,
};
return do_proc_douintvec(table, write, buffer, lenp, ppos,
     do_proc_douintvec_minmax_conv, ¶m);
}

/**
* proc_dou8vec_minmax - read a vector of unsigned chars with min/max values
* @table: the sysctl table
* @write: %TRUE if this is a write to the sysctl file
* @buffer: the user buffer
* @lenp: the size of the user buffer
* @ppos: file position
*
* Reads/writes up to table->maxlen/sizeof(u8) unsigned chars
* values from/to the user buffer, treated as an ASCII string. Negative
* strings are not allowed.
*
* This routine will ensure the values are within the range specified by
* table->extra1 (min) and table->extra2 (max).
*
* Returns 0 on success or an error on write when the range check fails.
*/
int proc_dou8vec_minmax(const struct ctl_table *table, int write,
   void *buffer, size_t *lenp, loff_t *ppos)
{
struct ctl_table tmp;
unsigned int min = 0, max = 255U, val;
u8 *data = table->data;
struct do_proc_douintvec_minmax_conv_param param = {
  .min = &min,
  .max = &max,
};
int res;

/* Do not support arrays yet. */
if (table->maxlen != sizeof(u8))
  return -EINVAL;

if (table->extra1)
  min = *(unsigned int *) table->extra1;
if (table->extra2)
  max = *(unsigned int *) table->extra2;

tmp = *table;

tmp.maxlen = sizeof(val);
tmp.data = &val;
val = READ_ONCE(*data);
res = do_proc_douintvec(&tmp, write, buffer, lenp, ppos,
    do_proc_douintvec_minmax_conv, ¶m);
if (res)
  return res;
if (write)
  WRITE_ONCE(*data, val);
return 0;
}
EXPORT_SYMBOL_GPL(proc_dou8vec_minmax);

static int __do_proc_doulongvec_minmax(void *data,
  const struct ctl_table *table, int write,
  void *buffer, size_t *lenp, loff_t *ppos,
  unsigned long convmul, unsigned long convdiv)
{
unsigned long *i, *min, *max;
int vleft, first = 1, err = 0;
size_t left;
char *p;

if (!data || !table->maxlen || !*lenp || (*ppos && !write)) {
  *lenp = 0;
  return 0;
}

i = data;
min = table->extra1;
max = table->extra2;
vleft = table->maxlen / sizeof(unsigned long);
left = *lenp;

if (write) {
  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++, first = 0) {
  unsigned long val;

  if (write) {
   bool neg;

   proc_skip_spaces(&p, &left);
   if (!left)
    break;

   err = proc_get_long(&p, &left, &val, &neg,
          proc_wspace_sep,
          sizeof(proc_wspace_sep), NULL);
   if (err || neg) {
    err = -EINVAL;
    break;
   }

   val = convmul * val / convdiv;
   if ((min && val < *min) || (max && val > *max)) {
    err = -EINVAL;
    break;
   }
   WRITE_ONCE(*i, val);
  } else {
   val = convdiv * READ_ONCE(*i) / convmul;
   if (!first)
    proc_put_char(&buffer, &left, '\t');
   proc_put_long(&buffer, &left, val, false);
  }
}

if (!write && !first && left && !err)
  proc_put_char(&buffer, &left, '\n');
if (write && !err)
  proc_skip_spaces(&p, &left);
if (write && first)
  return err ? : -EINVAL;
*lenp -= left;
out:
*ppos += *lenp;
return err;
}

static int do_proc_doulongvec_minmax(const struct ctl_table *table, int write,
  void *buffer, size_t *lenp, loff_t *ppos, unsigned long convmul,
  unsigned long convdiv)
{
return __do_proc_doulongvec_minmax(table->data, table, write,
   buffer, lenp, ppos, convmul, convdiv);
}

/**
* proc_doulongvec_minmax - read a vector of long integers with min/max values
* @table: the sysctl table
* @write: %TRUE if this is a write to the sysctl file
* @buffer: the user buffer
* @lenp: the size of the user buffer
* @ppos: file position
*
* Reads/writes up to table->maxlen/sizeof(unsigned long) unsigned long
* values from/to the user buffer, treated as an ASCII string.
*
* This routine will ensure the values are within the range specified by
* table->extra1 (min) and table->extra2 (max).
*
* Returns 0 on success.
*/
int proc_doulongvec_minmax(const struct ctl_table *table, int write,
      void *buffer, size_t *lenp, loff_t *ppos)
{
    return do_proc_doulongvec_minmax(table, write, buffer, lenp, ppos, 1l, 1l);
}

/**
* proc_doulongvec_ms_jiffies_minmax - read a vector of millisecond values with min/max values
* @table: the sysctl table
* @write: %TRUE if this is a write to the sysctl file
* @buffer: the user buffer
* @lenp: the size of the user buffer
* @ppos: file position
*
* Reads/writes up to table->maxlen/sizeof(unsigned long) unsigned long
* values from/to the user buffer, treated as an ASCII string. The values
* are treated as milliseconds, and converted to jiffies when they are stored.
*
* This routine will ensure the values are within the range specified by
* table->extra1 (min) and table->extra2 (max).
*
* Returns 0 on success.
*/
int proc_doulongvec_ms_jiffies_minmax(const struct ctl_table *table, int write,
          void *buffer, size_t *lenp, loff_t *ppos)
{
    return do_proc_doulongvec_minmax(table, write, buffer,
         lenp, ppos, HZ, 1000l);
}

static int do_proc_dointvec_jiffies_conv(bool *negp, unsigned long *lvalp,
      int *valp,
      int write, void *data)
{
if (write) {
  if (*lvalp > INT_MAX / HZ)
   return 1;
  if (*negp)
   WRITE_ONCE(*valp, -*lvalp * HZ);
  else
   WRITE_ONCE(*valp, *lvalp * HZ);
} else {
  int val = READ_ONCE(*valp);
  unsigned long lval;
  if (val < 0) {
   *negp = true;
   lval = -(unsigned long)val;
  } else {
   *negp = false;
   lval = (unsigned long)val;
  }
  *lvalp = lval / HZ;
}
return 0;
}

static int do_proc_dointvec_userhz_jiffies_conv(bool *negp, unsigned long *lvalp,
      int *valp,
      int write, void *data)
{
if (write) {
  if (USER_HZ < HZ && *lvalp > (LONG_MAX / HZ) * USER_HZ)
   return 1;
  *valp = clock_t_to_jiffies(*negp ? -*lvalp : *lvalp);
} else {
  int val = *valp;
  unsigned long lval;
  if (val < 0) {
   *negp = true;
   lval = -(unsigned long)val;
  } else {
   *negp = false;
   lval = (unsigned long)val;
  }
  *lvalp = jiffies_to_clock_t(lval);
}
return 0;
}

static int do_proc_dointvec_ms_jiffies_conv(bool *negp, unsigned long *lvalp,
         int *valp,
         int write, void *data)
{
if (write) {
  unsigned long jif = msecs_to_jiffies(*negp ? -*lvalp : *lvalp);

  if (jif > INT_MAX)
   return 1;
  WRITE_ONCE(*valp, (int)jif);
} else {
  int val = READ_ONCE(*valp);
  unsigned long lval;
  if (val < 0) {
   *negp = true;
   lval = -(unsigned long)val;
  } else {
   *negp = false;
   lval = (unsigned long)val;
  }
  *lvalp = jiffies_to_msecs(lval);
}
return 0;
}

static int do_proc_dointvec_ms_jiffies_minmax_conv(bool *negp, unsigned long *lvalp,
      int *valp, int write, void *data)
{
int tmp, ret;
struct do_proc_dointvec_minmax_conv_param *param = data;
/*
* If writing, first do so via a temporary local int so we can
* bounds-check it before touching *valp.
*/
int *ip = write ? &tmp : valp;

ret = do_proc_dointvec_ms_jiffies_conv(negp, lvalp, ip, write, data);
if (ret)
  return ret;

if (write) {
  if ((param->min && *param->min > tmp) ||
    (param->max && *param->max < tmp))
   return -EINVAL;
  *valp = tmp;
}
return 0;
}

/**
* proc_dointvec_jiffies - read a vector of integers as seconds
* @table: the sysctl table
* @write: %TRUE if this is a write to the sysctl file
* @buffer: the user buffer
* @lenp: the size of the user buffer
* @ppos: file position
*
* Reads/writes up to table->maxlen/sizeof(unsigned int) integer
* values from/to the user buffer, treated as an ASCII string.
* The values read are assumed to be in seconds, and are converted into
* jiffies.
*
* Returns 0 on success.
*/
int proc_dointvec_jiffies(const struct ctl_table *table, int write,
     void *buffer, size_t *lenp, loff_t *ppos)
{
    return do_proc_dointvec(table,write,buffer,lenp,ppos,
           do_proc_dointvec_jiffies_conv,NULL);
}

int proc_dointvec_ms_jiffies_minmax(const struct ctl_table *table, int write,
     void *buffer, size_t *lenp, loff_t *ppos)
{
struct do_proc_dointvec_minmax_conv_param param = {
  .min = (int *) table->extra1,
  .max = (int *) table->extra2,
};
return do_proc_dointvec(table, write, buffer, lenp, ppos,
   do_proc_dointvec_ms_jiffies_minmax_conv, ¶m);
}

/**
* proc_dointvec_userhz_jiffies - read a vector of integers as 1/USER_HZ seconds
* @table: the sysctl table
* @write: %TRUE if this is a write to the sysctl file
* @buffer: the user buffer
* @lenp: the size of the user buffer
* @ppos: pointer to the file position
*
* Reads/writes up to table->maxlen/sizeof(unsigned int) integer
* values from/to the user buffer, treated as an ASCII string.
* The values read are assumed to be in 1/USER_HZ seconds, and
* are converted into jiffies.
*
* Returns 0 on success.
*/
int proc_dointvec_userhz_jiffies(const struct ctl_table *table, int write,
     void *buffer, size_t *lenp, loff_t *ppos)
{
return do_proc_dointvec(table, write, buffer, lenp, ppos,
    do_proc_dointvec_userhz_jiffies_conv, NULL);
}

/**
* proc_dointvec_ms_jiffies - read a vector of integers as 1 milliseconds
* @table: the sysctl table
* @write: %TRUE if this is a write to the sysctl file
* @buffer: the user buffer
* @lenp: the size of the user buffer
* @ppos: the current position in the file
*
* Reads/writes up to table->maxlen/sizeof(unsigned int) integer
* values from/to the user buffer, treated as an ASCII string.
* The values read are assumed to be in 1/1000 seconds, and
* are converted into jiffies.
*
* Returns 0 on success.
*/
int proc_dointvec_ms_jiffies(const struct ctl_table *table, int write, void *buffer,
  size_t *lenp, loff_t *ppos)
{
return do_proc_dointvec(table, write, buffer, lenp, ppos,
    do_proc_dointvec_ms_jiffies_conv, NULL);
}

/**
* proc_do_large_bitmap - read/write from/to a large bitmap
* @table: the sysctl table
* @write: %TRUE if this is a write to the sysctl file
* @buffer: the user buffer
* @lenp: the size of the user buffer
* @ppos: file position
*
* The bitmap is stored at table->data and the bitmap length (in bits)
* in table->maxlen.
*
* We use a range comma separated format (e.g. 1,3-4,10-10) so that
* large bitmaps may be represented in a compact manner. Writing into
* the file will clear the bitmap then update it with the given input.
*
* Returns 0 on success.
*/
int proc_do_large_bitmap(const struct ctl_table *table, int write,
    void *buffer, size_t *lenp, loff_t *ppos)
{
int err = 0;
size_t left = *lenp;
unsigned long bitmap_len = table->maxlen;
unsigned long *bitmap = *(unsigned long **) table->data;
unsigned long *tmp_bitmap = NULL;
char tr_a[] = { '-', ',', '\n' }, tr_b[] = { ',', '\n', 0 }, c;

if (!bitmap || !bitmap_len || !left || (*ppos && !write)) {
  *lenp = 0;
  return 0;
}

if (write) {
  char *p = buffer;
  size_t skipped = 0;

  if (left > PAGE_SIZE - 1) {
   left = PAGE_SIZE - 1;
   /* How much of the buffer we'll skip this pass */
   skipped = *lenp - left;
  }

  tmp_bitmap = bitmap_zalloc(bitmap_len, GFP_KERNEL);
  if (!tmp_bitmap)
   return -ENOMEM;
  proc_skip_char(&p, &left, '\n');
  while (!err && left) {
   unsigned long val_a, val_b;
   bool neg;
   size_t saved_left;

   /* In case we stop parsing mid-number, we can reset */
   saved_left = left;
   err = proc_get_long(&p, &left, &val_a, &neg, tr_a,
          sizeof(tr_a), &c);
   /*
* If we consumed the entirety of a truncated buffer or
* only one char is left (may be a "-"), then stop here,
* reset, & come back for more.
*/
   if ((left <= 1) && skipped) {
    left = saved_left;
    break;
   }

   if (err)
    break;
   if (val_a >= bitmap_len || neg) {
    err = -EINVAL;
    break;
   }

   val_b = val_a;
   if (left) {
    p++;
    left--;
   }

   if (c == '-') {
    err = proc_get_long(&p, &left, &val_b,
           &neg, tr_b, sizeof(tr_b),
           &c);
    /*
* If we consumed all of a truncated buffer or
* then stop here, reset, & come back for more.
*/
    if (!left && skipped) {
     left = saved_left;
     break;
    }

    if (err)
     break;
    if (val_b >= bitmap_len || neg ||
        val_a > val_b) {
     err = -EINVAL;
     break;
    }
    if (left) {
     p++;
     left--;
    }
   }

   bitmap_set(tmp_bitmap, val_a, val_b - val_a + 1);
   proc_skip_char(&p, &left, '\n');
  }
  left += skipped;
} else {
  unsigned long bit_a, bit_b = 0;
  bool first = 1;

  while (left) {
   bit_a = find_next_bit(bitmap, bitmap_len, bit_b);
   if (bit_a >= bitmap_len)
    break;
   bit_b = find_next_zero_bit(bitmap, bitmap_len,
         bit_a + 1) - 1;

   if (!first)
    proc_put_char(&buffer, &left, ',');
   proc_put_long(&buffer, &left, bit_a, false);
   if (bit_a != bit_b) {
    proc_put_char(&buffer, &left, '-');
    proc_put_long(&buffer, &left, bit_b, false);
   }

   first = 0; bit_b++;
  }
  proc_put_char(&buffer, &left, '\n');
}

if (!err) {
  if (write) {
   if (*ppos)
    bitmap_or(bitmap, bitmap, tmp_bitmap, bitmap_len);
   else
    bitmap_copy(bitmap, tmp_bitmap, bitmap_len);
  }
  *lenp -= left;
  *ppos += *lenp;
}

bitmap_free(tmp_bitmap);
return err;
}

#else /* CONFIG_PROC_SYSCTL */

int proc_dostring(const struct ctl_table *table, int write,
    void *buffer, size_t *lenp, loff_t *ppos)
{
return -ENOSYS;
}

int proc_dobool(const struct ctl_table *table, int write,
  void *buffer, size_t *lenp, loff_t *ppos)
{
return -ENOSYS;
}

int proc_dointvec(const struct ctl_table *table, int write,
    void *buffer, size_t *lenp, loff_t *ppos)
{
return -ENOSYS;
}

int proc_douintvec(const struct ctl_table *table, int write,
    void *buffer, size_t *lenp, loff_t *ppos)
{
return -ENOSYS;
}

int proc_dointvec_minmax(const struct ctl_table *table, int write,
      void *buffer, size_t *lenp, loff_t *ppos)
{
return -ENOSYS;
}

int proc_douintvec_minmax(const struct ctl_table *table, int write,
     void *buffer, size_t *lenp, loff_t *ppos)
{
return -ENOSYS;
}

int proc_dou8vec_minmax(const struct ctl_table *table, int write,
   void *buffer, size_t *lenp, loff_t *ppos)
{
return -ENOSYS;
}

int proc_dointvec_jiffies(const struct ctl_table *table, int write,
      void *buffer, size_t *lenp, loff_t *ppos)
{
return -ENOSYS;
}

int proc_dointvec_ms_jiffies_minmax(const struct ctl_table *table, int write,
        void *buffer, size_t *lenp, loff_t *ppos)
{
return -ENOSYS;
}

int proc_dointvec_userhz_jiffies(const struct ctl_table *table, int write,
      void *buffer, size_t *lenp, loff_t *ppos)
{
return -ENOSYS;
}

int proc_dointvec_ms_jiffies(const struct ctl_table *table, int write,
        void *buffer, size_t *lenp, loff_t *ppos)
{
return -ENOSYS;
}

int proc_doulongvec_minmax(const struct ctl_table *table, int write,
      void *buffer, size_t *lenp, loff_t *ppos)
{
return -ENOSYS;
}

int proc_doulongvec_ms_jiffies_minmax(const struct ctl_table *table, int write,
          void *buffer, size_t *lenp, loff_t *ppos)
{
return -ENOSYS;
}

int proc_do_large_bitmap(const struct ctl_table *table, int write,
    void *buffer, size_t *lenp, loff_t *ppos)
{
return -ENOSYS;
}

#endif /* CONFIG_PROC_SYSCTL */

#if defined(CONFIG_SYSCTL)
int proc_do_static_key(const struct ctl_table *table, int write,
         void *buffer, size_t *lenp, loff_t *ppos)
{
struct static_key *key = (struct static_key *)table->data;
static DEFINE_MUTEX(static_key_mutex);
int val, ret;
struct ctl_table tmp = {
  .data   = &val,
  .maxlen = sizeof(val),
  .mode   = table->mode,
  .extra1 = SYSCTL_ZERO,
  .extra2 = SYSCTL_ONE,
};

if (write && !capable(CAP_SYS_ADMIN))
  return -EPERM;

mutex_lock(&static_key_mutex);
val = static_key_enabled(key);
ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
if (write && !ret) {
  if (val)
   static_key_enable(key);
  else
   static_key_disable(key);
}
mutex_unlock(&static_key_mutex);
return ret;
}

static const struct ctl_table sysctl_subsys_table[] = {
#ifdef CONFIG_PROC_SYSCTL
{
  .procname = "sysctl_writes_strict",
  .data  = &sysctl_writes_strict,
  .maxlen  = sizeof(int),
  .mode  = 0644,
  .proc_handler = proc_dointvec_minmax,
  .extra1  = SYSCTL_NEG_ONE,
  .extra2  = SYSCTL_ONE,
},
#endif
{
  .procname = "ngroups_max",
  .data  = (void *)&ngroups_max,
  .maxlen  = sizeof (int),
  .mode  = 0444,
  .proc_handler = proc_dointvec,
},
{
  .procname = "cap_last_cap",
  .data  = (void *)&cap_last_cap,
  .maxlen  = sizeof(int),
  .mode  = 0444,
  .proc_handler = proc_dointvec,
},
#ifdef CONFIG_SYSCTL_ARCH_UNALIGN_ALLOW
{
  .procname = "unaligned-trap",
  .data  = &unaligned_enabled,
  .maxlen  = sizeof(int),
  .mode  = 0644,
  .proc_handler = proc_dointvec,
},
#endif
#ifdef CONFIG_SYSCTL_ARCH_UNALIGN_NO_WARN
{
  .procname = "ignore-unaligned-usertrap",
  .data  = &no_unaligned_warning,
  .maxlen  = sizeof (int),
  .mode  = 0644,
  .proc_handler = proc_dointvec,
},
#endif
};

int __init sysctl_init_bases(void)
{
register_sysctl_init("kernel", sysctl_subsys_table);

return 0;
}
#endif /* CONFIG_SYSCTL */
/*
* No sense putting this after each symbol definition, twice,
* exception granted :-)
*/
EXPORT_SYMBOL(proc_dobool);
EXPORT_SYMBOL(proc_dointvec);
EXPORT_SYMBOL(proc_douintvec);
EXPORT_SYMBOL(proc_dointvec_jiffies);
EXPORT_SYMBOL(proc_dointvec_minmax);
EXPORT_SYMBOL_GPL(proc_douintvec_minmax);
EXPORT_SYMBOL(proc_dointvec_userhz_jiffies);
EXPORT_SYMBOL(proc_dointvec_ms_jiffies);
EXPORT_SYMBOL(proc_dostring);
EXPORT_SYMBOL(proc_doulongvec_minmax);
EXPORT_SYMBOL(proc_doulongvec_ms_jiffies_minmax);
EXPORT_SYMBOL(proc_do_large_bitmap);

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