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vsprintf.c
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// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/lib/vsprintf.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
/* vsprintf.c -- Lars Wirzenius & Linus Torvalds. */
/*
* Wirzenius wrote this portably, Torvalds fucked it up :-)
*/
/*
* Fri Jul 13 2001 Crutcher Dunnavant <[email protected]>
* - changed to provide snprintf and vsnprintf functions
* So Feb 1 16:51:32 CET 2004 Juergen Quade <[email protected]>
* - scnprintf and vscnprintf
*/
#include <linux/stdarg.h>
#include <linux/build_bug.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/errname.h>
#include <linux/module.h> /* for KSYM_SYMBOL_LEN */
#include <linux/types.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/kernel.h>
#include <linux/kallsyms.h>
#include <linux/math64.h>
#include <linux/uaccess.h>
#include <linux/ioport.h>
#include <linux/dcache.h>
#include <linux/cred.h>
#include <linux/rtc.h>
#include <linux/sprintf.h>
#include <linux/time.h>
#include <linux/uuid.h>
#include <linux/of.h>
#include <net/addrconf.h>
#include <linux/siphash.h>
#include <linux/compiler.h>
#include <linux/property.h>
#include <linux/notifier.h>
#ifdef CONFIG_BLOCK
#include <linux/blkdev.h>
#endif
#include "../mm/internal.h" /* For the trace_print_flags arrays */
#include <asm/page.h> /* for PAGE_SIZE */
#include <asm/byteorder.h> /* cpu_to_le16 */
#include <asm/unaligned.h>
#include <linux/string_helpers.h>
#include "kstrtox.h"
/* Disable pointer hashing if requested */
bool no_hash_pointers __ro_after_init;
EXPORT_SYMBOL_GPL(no_hash_pointers);
noinline
static unsigned long long simple_strntoull(const char *startp, char **endp, unsigned int base, size_t max_chars)
{
const char *cp;
unsigned long long result = 0ULL;
size_t prefix_chars;
unsigned int rv;
cp = _parse_integer_fixup_radix(startp, &base);
prefix_chars = cp - startp;
if (prefix_chars < max_chars) {
rv = _parse_integer_limit(cp, base, &result, max_chars - prefix_chars);
/* FIXME */
cp += (rv & ~KSTRTOX_OVERFLOW);
} else {
/* Field too short for prefix + digit, skip over without converting */
cp = startp + max_chars;
}
if (endp)
*endp = (char *)cp;
return result;
}
/**
* simple_strtoull - convert a string to an unsigned long long
* @cp: The start of the string
* @endp: A pointer to the end of the parsed string will be placed here
* @base: The number base to use
*
* This function has caveats. Please use kstrtoull instead.
*/
noinline
unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base)
{
return simple_strntoull(cp, endp, base, INT_MAX);
}
EXPORT_SYMBOL(simple_strtoull);
/**
* simple_strtoul - convert a string to an unsigned long
* @cp: The start of the string
* @endp: A pointer to the end of the parsed string will be placed here
* @base: The number base to use
*
* This function has caveats. Please use kstrtoul instead.
*/
unsigned long simple_strtoul(const char *cp, char **endp, unsigned int base)
{
return simple_strtoull(cp, endp, base);
}
EXPORT_SYMBOL(simple_strtoul);
/**
* simple_strtol - convert a string to a signed long
* @cp: The start of the string
* @endp: A pointer to the end of the parsed string will be placed here
* @base: The number base to use
*
* This function has caveats. Please use kstrtol instead.
*/
long simple_strtol(const char *cp, char **endp, unsigned int base)
{
if (*cp == '-')
return -simple_strtoul(cp + 1, endp, base);
return simple_strtoul(cp, endp, base);
}
EXPORT_SYMBOL(simple_strtol);
noinline
static long long simple_strntoll(const char *cp, char **endp, unsigned int base, size_t max_chars)
{
/*
* simple_strntoull() safely handles receiving max_chars==0 in the
* case cp[0] == '-' && max_chars == 1.
* If max_chars == 0 we can drop through and pass it to simple_strntoull()
* and the content of *cp is irrelevant.
*/
if (*cp == '-' && max_chars > 0)
return -simple_strntoull(cp + 1, endp, base, max_chars - 1);
return simple_strntoull(cp, endp, base, max_chars);
}
/**
* simple_strtoll - convert a string to a signed long long
* @cp: The start of the string
* @endp: A pointer to the end of the parsed string will be placed here
* @base: The number base to use
*
* This function has caveats. Please use kstrtoll instead.
*/
long long simple_strtoll(const char *cp, char **endp, unsigned int base)
{
return simple_strntoll(cp, endp, base, INT_MAX);
}
EXPORT_SYMBOL(simple_strtoll);
static noinline_for_stack
int skip_atoi(const char **s)
{
int i = 0;
do {
i = i*10 + *((*s)++) - '0';
} while (isdigit(**s));
return i;
}
/*
* Decimal conversion is by far the most typical, and is used for
* /proc and /sys data. This directly impacts e.g. top performance
* with many processes running. We optimize it for speed by emitting
* two characters at a time, using a 200 byte lookup table. This
* roughly halves the number of multiplications compared to computing
* the digits one at a time. Implementation strongly inspired by the
* previous version, which in turn used ideas described at
* <http://www.cs.uiowa.edu/~jones/bcd/divide.html> (with permission
* from the author, Douglas W. Jones).
*
* It turns out there is precisely one 26 bit fixed-point
* approximation a of 64/100 for which x/100 == (x * (u64)a) >> 32
* holds for all x in [0, 10^8-1], namely a = 0x28f5c29. The actual
* range happens to be somewhat larger (x <= 1073741898), but that's
* irrelevant for our purpose.
*
* For dividing a number in the range [10^4, 10^6-1] by 100, we still
* need a 32x32->64 bit multiply, so we simply use the same constant.
*
* For dividing a number in the range [100, 10^4-1] by 100, there are
* several options. The simplest is (x * 0x147b) >> 19, which is valid
* for all x <= 43698.
*/
static const u16 decpair[100] = {
#define _(x) (__force u16) cpu_to_le16(((x % 10) | ((x / 10) << 8)) + 0x3030)
_( 0), _( 1), _( 2), _( 3), _( 4), _( 5), _( 6), _( 7), _( 8), _( 9),
_(10), _(11), _(12), _(13), _(14), _(15), _(16), _(17), _(18), _(19),
_(20), _(21), _(22), _(23), _(24), _(25), _(26), _(27), _(28), _(29),
_(30), _(31), _(32), _(33), _(34), _(35), _(36), _(37), _(38), _(39),
_(40), _(41), _(42), _(43), _(44), _(45), _(46), _(47), _(48), _(49),
_(50), _(51), _(52), _(53), _(54), _(55), _(56), _(57), _(58), _(59),
_(60), _(61), _(62), _(63), _(64), _(65), _(66), _(67), _(68), _(69),
_(70), _(71), _(72), _(73), _(74), _(75), _(76), _(77), _(78), _(79),
_(80), _(81), _(82), _(83), _(84), _(85), _(86), _(87), _(88), _(89),
_(90), _(91), _(92), _(93), _(94), _(95), _(96), _(97), _(98), _(99),
#undef _
};
/*
* This will print a single '0' even if r == 0, since we would
* immediately jump to out_r where two 0s would be written but only
* one of them accounted for in buf. This is needed by ip4_string
* below. All other callers pass a non-zero value of r.
*/
static noinline_for_stack
char *put_dec_trunc8(char *buf, unsigned r)
{
unsigned q;
/* 1 <= r < 10^8 */
if (r < 100)
goto out_r;
/* 100 <= r < 10^8 */
q = (r * (u64)0x28f5c29) >> 32;
*((u16 *)buf) = decpair[r - 100*q];
buf += 2;
/* 1 <= q < 10^6 */
if (q < 100)
goto out_q;
/* 100 <= q < 10^6 */
r = (q * (u64)0x28f5c29) >> 32;
*((u16 *)buf) = decpair[q - 100*r];
buf += 2;
/* 1 <= r < 10^4 */
if (r < 100)
goto out_r;
/* 100 <= r < 10^4 */
q = (r * 0x147b) >> 19;
*((u16 *)buf) = decpair[r - 100*q];
buf += 2;
out_q:
/* 1 <= q < 100 */
r = q;
out_r:
/* 1 <= r < 100 */
*((u16 *)buf) = decpair[r];
buf += r < 10 ? 1 : 2;
return buf;
}
#if BITS_PER_LONG == 64 && BITS_PER_LONG_LONG == 64
static noinline_for_stack
char *put_dec_full8(char *buf, unsigned r)
{
unsigned q;
/* 0 <= r < 10^8 */
q = (r * (u64)0x28f5c29) >> 32;
*((u16 *)buf) = decpair[r - 100*q];
buf += 2;
/* 0 <= q < 10^6 */
r = (q * (u64)0x28f5c29) >> 32;
*((u16 *)buf) = decpair[q - 100*r];
buf += 2;
/* 0 <= r < 10^4 */
q = (r * 0x147b) >> 19;
*((u16 *)buf) = decpair[r - 100*q];
buf += 2;
/* 0 <= q < 100 */
*((u16 *)buf) = decpair[q];
buf += 2;
return buf;
}
static noinline_for_stack
char *put_dec(char *buf, unsigned long long n)
{
if (n >= 100*1000*1000)
buf = put_dec_full8(buf, do_div(n, 100*1000*1000));
/* 1 <= n <= 1.6e11 */
if (n >= 100*1000*1000)
buf = put_dec_full8(buf, do_div(n, 100*1000*1000));
/* 1 <= n < 1e8 */
return put_dec_trunc8(buf, n);
}
#elif BITS_PER_LONG == 32 && BITS_PER_LONG_LONG == 64
static void
put_dec_full4(char *buf, unsigned r)
{
unsigned q;
/* 0 <= r < 10^4 */
q = (r * 0x147b) >> 19;
*((u16 *)buf) = decpair[r - 100*q];
buf += 2;
/* 0 <= q < 100 */
*((u16 *)buf) = decpair[q];
}
/*
* Call put_dec_full4 on x % 10000, return x / 10000.
* The approximation x/10000 == (x * 0x346DC5D7) >> 43
* holds for all x < 1,128,869,999. The largest value this
* helper will ever be asked to convert is 1,125,520,955.
* (second call in the put_dec code, assuming n is all-ones).
*/
static noinline_for_stack
unsigned put_dec_helper4(char *buf, unsigned x)
{
uint32_t q = (x * (uint64_t)0x346DC5D7) >> 43;
put_dec_full4(buf, x - q * 10000);
return q;
}
/* Based on code by Douglas W. Jones found at
* <http://www.cs.uiowa.edu/~jones/bcd/decimal.html#sixtyfour>
* (with permission from the author).
* Performs no 64-bit division and hence should be fast on 32-bit machines.
*/
static
char *put_dec(char *buf, unsigned long long n)
{
uint32_t d3, d2, d1, q, h;
if (n < 100*1000*1000)
return put_dec_trunc8(buf, n);
d1 = ((uint32_t)n >> 16); /* implicit "& 0xffff" */
h = (n >> 32);
d2 = (h ) & 0xffff;
d3 = (h >> 16); /* implicit "& 0xffff" */
/* n = 2^48 d3 + 2^32 d2 + 2^16 d1 + d0
= 281_4749_7671_0656 d3 + 42_9496_7296 d2 + 6_5536 d1 + d0 */
q = 656 * d3 + 7296 * d2 + 5536 * d1 + ((uint32_t)n & 0xffff);
q = put_dec_helper4(buf, q);
q += 7671 * d3 + 9496 * d2 + 6 * d1;
q = put_dec_helper4(buf+4, q);
q += 4749 * d3 + 42 * d2;
q = put_dec_helper4(buf+8, q);
q += 281 * d3;
buf += 12;
if (q)
buf = put_dec_trunc8(buf, q);
else while (buf[-1] == '0')
--buf;
return buf;
}
#endif
/*
* Convert passed number to decimal string.
* Returns the length of string. On buffer overflow, returns 0.
*
* If speed is not important, use snprintf(). It's easy to read the code.
*/
int num_to_str(char *buf, int size, unsigned long long num, unsigned int width)
{
/* put_dec requires 2-byte alignment of the buffer. */
char tmp[sizeof(num) * 3] __aligned(2);
int idx, len;
/* put_dec() may work incorrectly for num = 0 (generate "", not "0") */
if (num <= 9) {
tmp[0] = '0' + num;
len = 1;
} else {
len = put_dec(tmp, num) - tmp;
}
if (len > size || width > size)
return 0;
if (width > len) {
width = width - len;
for (idx = 0; idx < width; idx++)
buf[idx] = ' ';
} else {
width = 0;
}
for (idx = 0; idx < len; ++idx)
buf[idx + width] = tmp[len - idx - 1];
return len + width;
}
#define SIGN 1 /* unsigned/signed, must be 1 */
#define LEFT 2 /* left justified */
#define PLUS 4 /* show plus */
#define SPACE 8 /* space if plus */
#define ZEROPAD 16 /* pad with zero, must be 16 == '0' - ' ' */
#define SMALL 32 /* use lowercase in hex (must be 32 == 0x20) */
#define SPECIAL 64 /* prefix hex with "0x", octal with "0" */
static_assert(SIGN == 1);
static_assert(ZEROPAD == ('0' - ' '));
static_assert(SMALL == ('a' ^ 'A'));
enum format_type {
FORMAT_TYPE_NONE, /* Just a string part */
FORMAT_TYPE_WIDTH,
FORMAT_TYPE_PRECISION,
FORMAT_TYPE_CHAR,
FORMAT_TYPE_STR,
FORMAT_TYPE_PTR,
FORMAT_TYPE_PERCENT_CHAR,
FORMAT_TYPE_INVALID,
FORMAT_TYPE_LONG_LONG,
FORMAT_TYPE_ULONG,
FORMAT_TYPE_LONG,
FORMAT_TYPE_UBYTE,
FORMAT_TYPE_BYTE,
FORMAT_TYPE_USHORT,
FORMAT_TYPE_SHORT,
FORMAT_TYPE_UINT,
FORMAT_TYPE_INT,
FORMAT_TYPE_SIZE_T,
FORMAT_TYPE_PTRDIFF
};
struct printf_spec {
unsigned int type:8; /* format_type enum */
signed int field_width:24; /* width of output field */
unsigned int flags:8; /* flags to number() */
unsigned int base:8; /* number base, 8, 10 or 16 only */
signed int precision:16; /* # of digits/chars */
} __packed;
static_assert(sizeof(struct printf_spec) == 8);
#define FIELD_WIDTH_MAX ((1 << 23) - 1)
#define PRECISION_MAX ((1 << 15) - 1)
static noinline_for_stack
char *number(char *buf, char *end, unsigned long long num,
struct printf_spec spec)
{
/* put_dec requires 2-byte alignment of the buffer. */
char tmp[3 * sizeof(num)] __aligned(2);
char sign;
char locase;
int need_pfx = ((spec.flags & SPECIAL) && spec.base != 10);
int i;
bool is_zero = num == 0LL;
int field_width = spec.field_width;
int precision = spec.precision;
/* locase = 0 or 0x20. ORing digits or letters with 'locase'
* produces same digits or (maybe lowercased) letters */
locase = (spec.flags & SMALL);
if (spec.flags & LEFT)
spec.flags &= ~ZEROPAD;
sign = 0;
if (spec.flags & SIGN) {
if ((signed long long)num < 0) {
sign = '-';
num = -(signed long long)num;
field_width--;
} else if (spec.flags & PLUS) {
sign = '+';
field_width--;
} else if (spec.flags & SPACE) {
sign = ' ';
field_width--;
}
}
if (need_pfx) {
if (spec.base == 16)
field_width -= 2;
else if (!is_zero)
field_width--;
}
/* generate full string in tmp[], in reverse order */
i = 0;
if (num < spec.base)
tmp[i++] = hex_asc_upper[num] | locase;
else if (spec.base != 10) { /* 8 or 16 */
int mask = spec.base - 1;
int shift = 3;
if (spec.base == 16)
shift = 4;
do {
tmp[i++] = (hex_asc_upper[((unsigned char)num) & mask] | locase);
num >>= shift;
} while (num);
} else { /* base 10 */
i = put_dec(tmp, num) - tmp;
}
/* printing 100 using %2d gives "100", not "00" */
if (i > precision)
precision = i;
/* leading space padding */
field_width -= precision;
if (!(spec.flags & (ZEROPAD | LEFT))) {
while (--field_width >= 0) {
if (buf < end)
*buf = ' ';
++buf;
}
}
/* sign */
if (sign) {
if (buf < end)
*buf = sign;
++buf;
}
/* "0x" / "0" prefix */
if (need_pfx) {
if (spec.base == 16 || !is_zero) {
if (buf < end)
*buf = '0';
++buf;
}
if (spec.base == 16) {
if (buf < end)
*buf = ('X' | locase);
++buf;
}
}
/* zero or space padding */
if (!(spec.flags & LEFT)) {
char c = ' ' + (spec.flags & ZEROPAD);
while (--field_width >= 0) {
if (buf < end)
*buf = c;
++buf;
}
}
/* hmm even more zero padding? */
while (i <= --precision) {
if (buf < end)
*buf = '0';
++buf;
}
/* actual digits of result */
while (--i >= 0) {
if (buf < end)
*buf = tmp[i];
++buf;
}
/* trailing space padding */
while (--field_width >= 0) {
if (buf < end)
*buf = ' ';
++buf;
}
return buf;
}
static noinline_for_stack
char *special_hex_number(char *buf, char *end, unsigned long long num, int size)
{
struct printf_spec spec;
spec.type = FORMAT_TYPE_PTR;
spec.field_width = 2 + 2 * size; /* 0x + hex */
spec.flags = SPECIAL | SMALL | ZEROPAD;
spec.base = 16;
spec.precision = -1;
return number(buf, end, num, spec);
}
static void move_right(char *buf, char *end, unsigned len, unsigned spaces)
{
size_t size;
if (buf >= end) /* nowhere to put anything */
return;
size = end - buf;
if (size <= spaces) {
memset(buf, ' ', size);
return;
}
if (len) {
if (len > size - spaces)
len = size - spaces;
memmove(buf + spaces, buf, len);
}
memset(buf, ' ', spaces);
}
/*
* Handle field width padding for a string.
* @buf: current buffer position
* @n: length of string
* @end: end of output buffer
* @spec: for field width and flags
* Returns: new buffer position after padding.
*/
static noinline_for_stack
char *widen_string(char *buf, int n, char *end, struct printf_spec spec)
{
unsigned spaces;
if (likely(n >= spec.field_width))
return buf;
/* we want to pad the sucker */
spaces = spec.field_width - n;
if (!(spec.flags & LEFT)) {
move_right(buf - n, end, n, spaces);
return buf + spaces;
}
while (spaces--) {
if (buf < end)
*buf = ' ';
++buf;
}
return buf;
}
/* Handle string from a well known address. */
static char *string_nocheck(char *buf, char *end, const char *s,
struct printf_spec spec)
{
int len = 0;
int lim = spec.precision;
while (lim--) {
char c = *s++;
if (!c)
break;
if (buf < end)
*buf = c;
++buf;
++len;
}
return widen_string(buf, len, end, spec);
}
static char *err_ptr(char *buf, char *end, void *ptr,
struct printf_spec spec)
{
int err = PTR_ERR(ptr);
const char *sym = errname(err);
if (sym)
return string_nocheck(buf, end, sym, spec);
/*
* Somebody passed ERR_PTR(-1234) or some other non-existing
* Efoo - or perhaps CONFIG_SYMBOLIC_ERRNAME=n. Fall back to
* printing it as its decimal representation.
*/
spec.flags |= SIGN;
spec.base = 10;
return number(buf, end, err, spec);
}
/* Be careful: error messages must fit into the given buffer. */
static char *error_string(char *buf, char *end, const char *s,
struct printf_spec spec)
{
/*
* Hard limit to avoid a completely insane messages. It actually
* works pretty well because most error messages are in
* the many pointer format modifiers.
*/
if (spec.precision == -1)
spec.precision = 2 * sizeof(void *);
return string_nocheck(buf, end, s, spec);
}
/*
* Do not call any complex external code here. Nested printk()/vsprintf()
* might cause infinite loops. Failures might break printk() and would
* be hard to debug.
*/
static const char *check_pointer_msg(const void *ptr)
{
if (!ptr)
return "(null)";
if ((unsigned long)ptr < PAGE_SIZE || IS_ERR_VALUE(ptr))
return "(efault)";
return NULL;
}
static int check_pointer(char **buf, char *end, const void *ptr,
struct printf_spec spec)
{
const char *err_msg;
err_msg = check_pointer_msg(ptr);
if (err_msg) {
*buf = error_string(*buf, end, err_msg, spec);
return -EFAULT;
}
return 0;
}
static noinline_for_stack
char *string(char *buf, char *end, const char *s,
struct printf_spec spec)
{
if (check_pointer(&buf, end, s, spec))
return buf;
return string_nocheck(buf, end, s, spec);
}
static char *pointer_string(char *buf, char *end,
const void *ptr,
struct printf_spec spec)
{
spec.base = 16;
spec.flags |= SMALL;
if (spec.field_width == -1) {
spec.field_width = 2 * sizeof(ptr);
spec.flags |= ZEROPAD;
}
return number(buf, end, (unsigned long int)ptr, spec);
}
/* Make pointers available for printing early in the boot sequence. */
static int debug_boot_weak_hash __ro_after_init;
static int __init debug_boot_weak_hash_enable(char *str)
{
debug_boot_weak_hash = 1;
pr_info("debug_boot_weak_hash enabled\n");
return 0;
}
early_param("debug_boot_weak_hash", debug_boot_weak_hash_enable);
static bool filled_random_ptr_key __read_mostly;
static siphash_key_t ptr_key __read_mostly;
static int fill_ptr_key(struct notifier_block *nb, unsigned long action, void *data)
{
get_random_bytes(&ptr_key, sizeof(ptr_key));
/* Pairs with smp_rmb() before reading ptr_key. */
smp_wmb();
WRITE_ONCE(filled_random_ptr_key, true);
return NOTIFY_DONE;
}
static int __init vsprintf_init_hashval(void)
{
static struct notifier_block fill_ptr_key_nb = { .notifier_call = fill_ptr_key };
execute_with_initialized_rng(&fill_ptr_key_nb);
return 0;
}
subsys_initcall(vsprintf_init_hashval)
/* Maps a pointer to a 32 bit unique identifier. */
static inline int __ptr_to_hashval(const void *ptr, unsigned long *hashval_out)
{
unsigned long hashval;
if (!READ_ONCE(filled_random_ptr_key))
return -EBUSY;
/* Pairs with smp_wmb() after writing ptr_key. */
smp_rmb();
#ifdef CONFIG_64BIT
hashval = (unsigned long)siphash_1u64((u64)ptr, &ptr_key);
/*
* Mask off the first 32 bits, this makes explicit that we have
* modified the address (and 32 bits is plenty for a unique ID).
*/
hashval = hashval & 0xffffffff;
#else
hashval = (unsigned long)siphash_1u32((u32)ptr, &ptr_key);
#endif
*hashval_out = hashval;
return 0;
}
int ptr_to_hashval(const void *ptr, unsigned long *hashval_out)
{
return __ptr_to_hashval(ptr, hashval_out);
}
static char *ptr_to_id(char *buf, char *end, const void *ptr,
struct printf_spec spec)
{
const char *str = sizeof(ptr) == 8 ? "(____ptrval____)" : "(ptrval)";
unsigned long hashval;
int ret;
/*
* Print the real pointer value for NULL and error pointers,
* as they are not actual addresses.
*/
if (IS_ERR_OR_NULL(ptr))
return pointer_string(buf, end, ptr, spec);
/* When debugging early boot use non-cryptographically secure hash. */
if (unlikely(debug_boot_weak_hash)) {
hashval = hash_long((unsigned long)ptr, 32);
return pointer_string(buf, end, (const void *)hashval, spec);
}
ret = __ptr_to_hashval(ptr, &hashval);
if (ret) {
spec.field_width = 2 * sizeof(ptr);
/* string length must be less than default_width */
return error_string(buf, end, str, spec);
}
return pointer_string(buf, end, (const void *)hashval, spec);
}
static char *default_pointer(char *buf, char *end, const void *ptr,
struct printf_spec spec)
{
/*
* default is to _not_ leak addresses, so hash before printing,
* unless no_hash_pointers is specified on the command line.
*/
if (unlikely(no_hash_pointers))
return pointer_string(buf, end, ptr, spec);
return ptr_to_id(buf, end, ptr, spec);
}
int kptr_restrict __read_mostly;
static noinline_for_stack
char *restricted_pointer(char *buf, char *end, const void *ptr,
struct printf_spec spec)
{
switch (kptr_restrict) {
case 0:
/* Handle as %p, hash and do _not_ leak addresses. */
return default_pointer(buf, end, ptr, spec);
case 1: {
const struct cred *cred;
/*
* kptr_restrict==1 cannot be used in IRQ context
* because its test for CAP_SYSLOG would be meaningless.
*/
if (in_hardirq() || in_serving_softirq() || in_nmi()) {
if (spec.field_width == -1)
spec.field_width = 2 * sizeof(ptr);
return error_string(buf, end, "pK-error", spec);
}
/*
* Only print the real pointer value if the current
* process has CAP_SYSLOG and is running with the
* same credentials it started with. This is because
* access to files is checked at open() time, but %pK
* checks permission at read() time. We don't want to
* leak pointer values if a binary opens a file using
* %pK and then elevates privileges before reading it.
*/
cred = current_cred();
if (!has_capability_noaudit(current, CAP_SYSLOG) ||
!uid_eq(cred->euid, cred->uid) ||
!gid_eq(cred->egid, cred->gid))
ptr = NULL;
break;
}
case 2:
default:
/* Always print 0's for %pK */
ptr = NULL;
break;
}
return pointer_string(buf, end, ptr, spec);
}
static noinline_for_stack
char *dentry_name(char *buf, char *end, const struct dentry *d, struct printf_spec spec,
const char *fmt)
{
const char *array[4], *s;
const struct dentry *p;
int depth;
int i, n;
switch (fmt[1]) {
case '2': case '3': case '4':
depth = fmt[1] - '0';
break;
default:
depth = 1;
}
rcu_read_lock();
for (i = 0; i < depth; i++, d = p) {
if (check_pointer(&buf, end, d, spec)) {
rcu_read_unlock();
return buf;
}
p = READ_ONCE(d->d_parent);
array[i] = READ_ONCE(d->d_name.name);
if (p == d) {
if (i)
array[i] = "";
i++;
break;
}
}
s = array[--i];
for (n = 0; n != spec.precision; n++, buf++) {
char c = *s++;
if (!c) {
if (!i)
break;
c = '/';
s = array[--i];
}
if (buf < end)
*buf = c;
}
rcu_read_unlock();
return widen_string(buf, n, end, spec);
}
static noinline_for_stack
char *file_dentry_name(char *buf, char *end, const struct file *f,
struct printf_spec spec, const char *fmt)
{
if (check_pointer(&buf, end, f, spec))
return buf;
return dentry_name(buf, end, f->f_path.dentry, spec, fmt);
}
#ifdef CONFIG_BLOCK
static noinline_for_stack
char *bdev_name(char *buf, char *end, struct block_device *bdev,
struct printf_spec spec, const char *fmt)
{
struct gendisk *hd;
if (check_pointer(&buf, end, bdev, spec))
return buf;
hd = bdev->bd_disk;
buf = string(buf, end, hd->disk_name, spec);
if (bdev_is_partition(bdev)) {
if (isdigit(hd->disk_name[strlen(hd->disk_name)-1])) {
if (buf < end)
*buf = 'p';
buf++;
}
buf = number(buf, end, bdev_partno(bdev), spec);
}
return buf;
}
#endif
static noinline_for_stack
char *symbol_string(char *buf, char *end, void *ptr,
struct printf_spec spec, const char *fmt)
{
unsigned long value;
#ifdef CONFIG_KALLSYMS
char sym[KSYM_SYMBOL_LEN];
#endif
if (fmt[1] == 'R')
ptr = __builtin_extract_return_addr(ptr);
value = (unsigned long)ptr;
#ifdef CONFIG_KALLSYMS
if (*fmt == 'B' && fmt[1] == 'b')
sprint_backtrace_build_id(sym, value);
else if (*fmt == 'B')
sprint_backtrace(sym, value);
else if (*fmt == 'S' && (fmt[1] == 'b' || (fmt[1] == 'R' && fmt[2] == 'b')))
sprint_symbol_build_id(sym, value);