printf: Remove unused 'bprintf'

[drm/drm-misc.git] / include / linux / fortify-string.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_FORTIFY_STRING_H_
#define _LINUX_FORTIFY_STRING_H_

#include <linux/bitfield.h>
#include <linux/bug.h>
#include <linux/const.h>
#include <linux/limits.h>

#define __FORTIFY_INLINE extern __always_inline __gnu_inline __overloadable
#define __RENAME(x) __asm__(#x)

#define FORTIFY_REASON_DIR(r)           FIELD_GET(BIT(0), r)
#define FORTIFY_REASON_FUNC(r)          FIELD_GET(GENMASK(7, 1), r)
#define FORTIFY_REASON(func, write)     (FIELD_PREP(BIT(0), write) | \
                                         FIELD_PREP(GENMASK(7, 1), func))

/* Overridden by KUnit tests. */
#ifndef fortify_panic
# define fortify_panic(func, write, avail, size, retfail)       \
         __fortify_panic(FORTIFY_REASON(func, write), avail, size)
#endif
#ifndef fortify_warn_once
# define fortify_warn_once(x...)        WARN_ONCE(x)
#endif

#define FORTIFY_READ             0
#define FORTIFY_WRITE            1

#define EACH_FORTIFY_FUNC(macro)        \
        macro(strncpy),                 \
        macro(strnlen),                 \
        macro(strlen),                  \
        macro(strscpy),                 \
        macro(strlcat),                 \
        macro(strcat),                  \
        macro(strncat),                 \
        macro(memset),                  \
        macro(memcpy),                  \
        macro(memmove),                 \
        macro(memscan),                 \
        macro(memcmp),                  \
        macro(memchr),                  \
        macro(memchr_inv),              \
        macro(kmemdup),                 \
        macro(strcpy),                  \
        macro(UNKNOWN),

#define MAKE_FORTIFY_FUNC(func) FORTIFY_FUNC_##func

enum fortify_func {
        EACH_FORTIFY_FUNC(MAKE_FORTIFY_FUNC)
};

void __fortify_report(const u8 reason, const size_t avail, const size_t size);
void __fortify_panic(const u8 reason, const size_t avail, const size_t size) __cold __noreturn;
void __read_overflow(void) __compiletime_error("detected read beyond size of object (1st parameter)");
void __read_overflow2(void) __compiletime_error("detected read beyond size of object (2nd parameter)");
void __read_overflow2_field(size_t avail, size_t wanted) __compiletime_warning("detected read beyond size of field (2nd parameter); maybe use struct_group()?");
void __write_overflow(void) __compiletime_error("detected write beyond size of object (1st parameter)");
void __write_overflow_field(size_t avail, size_t wanted) __compiletime_warning("detected write beyond size of field (1st parameter); maybe use struct_group()?");

#define __compiletime_strlen(p)                                 \
({                                                              \
        char *__p = (char *)(p);                                \
        size_t __ret = SIZE_MAX;                                \
        const size_t __p_size = __member_size(p);               \
        if (__p_size != SIZE_MAX &&                             \
            __builtin_constant_p(*__p)) {                       \
                size_t __p_len = __p_size - 1;                  \
                if (__builtin_constant_p(__p[__p_len]) &&       \
                    __p[__p_len] == '\0')                       \
                        __ret = __builtin_strlen(__p);          \
        }                                                       \
        __ret;                                                  \
})

#if defined(__SANITIZE_ADDRESS__)

#if !defined(CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX) && !defined(CONFIG_GENERIC_ENTRY)
extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset);
extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove);
extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy);
#elif defined(CONFIG_KASAN_GENERIC)
extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(__asan_memset);
extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(__asan_memmove);
extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(__asan_memcpy);
#else /* CONFIG_KASAN_SW_TAGS */
extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(__hwasan_memset);
extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(__hwasan_memmove);
extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(__hwasan_memcpy);
#endif

extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr);
extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp);
extern char *__underlying_strcat(char *p, const char *q) __RENAME(strcat);
extern char *__underlying_strcpy(char *p, const char *q) __RENAME(strcpy);
extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen);
extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat);
extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy);

#else

#if defined(__SANITIZE_MEMORY__)
/*
 * For KMSAN builds all memcpy/memset/memmove calls should be replaced by the
 * corresponding __msan_XXX functions.
 */
#include <linux/kmsan_string.h>
#define __underlying_memcpy     __msan_memcpy
#define __underlying_memmove    __msan_memmove
#define __underlying_memset     __msan_memset
#else
#define __underlying_memcpy     __builtin_memcpy
#define __underlying_memmove    __builtin_memmove
#define __underlying_memset     __builtin_memset
#endif

#define __underlying_memchr     __builtin_memchr
#define __underlying_memcmp     __builtin_memcmp
#define __underlying_strcat     __builtin_strcat
#define __underlying_strcpy     __builtin_strcpy
#define __underlying_strlen     __builtin_strlen
#define __underlying_strncat    __builtin_strncat
#define __underlying_strncpy    __builtin_strncpy

#endif

/**
 * unsafe_memcpy - memcpy implementation with no FORTIFY bounds checking
 *
 * @dst: Destination memory address to write to
 * @src: Source memory address to read from
 * @bytes: How many bytes to write to @dst from @src
 * @justification: Free-form text or comment describing why the use is needed
 *
 * This should be used for corner cases where the compiler cannot do the
 * right thing, or during transitions between APIs, etc. It should be used
 * very rarely, and includes a place for justification detailing where bounds
 * checking has happened, and why existing solutions cannot be employed.
 */
#define unsafe_memcpy(dst, src, bytes, justification)           \
        __underlying_memcpy(dst, src, bytes)

/*
 * Clang's use of __builtin_*object_size() within inlines needs hinting via
 * __pass_*object_size(). The preference is to only ever use type 1 (member
 * size, rather than struct size), but there remain some stragglers using
 * type 0 that will be converted in the future.
 */
#if __has_builtin(__builtin_dynamic_object_size)
#define POS                     __pass_dynamic_object_size(1)
#define POS0                    __pass_dynamic_object_size(0)
#else
#define POS                     __pass_object_size(1)
#define POS0                    __pass_object_size(0)
#endif

#define __compiletime_lessthan(bounds, length)  (       \
        __builtin_constant_p((bounds) < (length)) &&    \
        (bounds) < (length)                             \
)

/**
 * strncpy - Copy a string to memory with non-guaranteed NUL padding
 *
 * @p: pointer to destination of copy
 * @q: pointer to NUL-terminated source string to copy
 * @size: bytes to write at @p
 *
 * If strlen(@q) >= @size, the copy of @q will stop after @size bytes,
 * and @p will NOT be NUL-terminated
 *
 * If strlen(@q) < @size, following the copy of @q, trailing NUL bytes
 * will be written to @p until @size total bytes have been written.
 *
 * Do not use this function. While FORTIFY_SOURCE tries to avoid
 * over-reads of @q, it cannot defend against writing unterminated
 * results to @p. Using strncpy() remains ambiguous and fragile.
 * Instead, please choose an alternative, so that the expectation
 * of @p's contents is unambiguous:
 *
 * +--------------------+--------------------+------------+
 * | **p** needs to be: | padded to **size** | not padded |
 * +====================+====================+============+
 * |     NUL-terminated | strscpy_pad()      | strscpy()  |
 * +--------------------+--------------------+------------+
 * | not NUL-terminated | strtomem_pad()     | strtomem() |
 * +--------------------+--------------------+------------+
 *
 * Note strscpy*()'s differing return values for detecting truncation,
 * and strtomem*()'s expectation that the destination is marked with
 * __nonstring when it is a character array.
 *
 */
__FORTIFY_INLINE __diagnose_as(__builtin_strncpy, 1, 2, 3)
char *strncpy(char * const POS p, const char *q, __kernel_size_t size)
{
        const size_t p_size = __member_size(p);

        if (__compiletime_lessthan(p_size, size))
                __write_overflow();
        if (p_size < size)
                fortify_panic(FORTIFY_FUNC_strncpy, FORTIFY_WRITE, p_size, size, p);
        return __underlying_strncpy(p, q, size);
}

extern __kernel_size_t __real_strnlen(const char *, __kernel_size_t) __RENAME(strnlen);
/**
 * strnlen - Return bounded count of characters in a NUL-terminated string
 *
 * @p: pointer to NUL-terminated string to count.
 * @maxlen: maximum number of characters to count.
 *
 * Returns number of characters in @p (NOT including the final NUL), or
 * @maxlen, if no NUL has been found up to there.
 *
 */
__FORTIFY_INLINE __kernel_size_t strnlen(const char * const POS p, __kernel_size_t maxlen)
{
        const size_t p_size = __member_size(p);
        const size_t p_len = __compiletime_strlen(p);
        size_t ret;

        /* We can take compile-time actions when maxlen is const. */
        if (__builtin_constant_p(maxlen) && p_len != SIZE_MAX) {
                /* If p is const, we can use its compile-time-known len. */
                if (maxlen >= p_size)
                        return p_len;
        }

        /* Do not check characters beyond the end of p. */
        ret = __real_strnlen(p, maxlen < p_size ? maxlen : p_size);
        if (p_size <= ret && maxlen != ret)
                fortify_panic(FORTIFY_FUNC_strnlen, FORTIFY_READ, p_size, ret + 1, ret);
        return ret;
}

/*
 * Defined after fortified strnlen to reuse it. However, it must still be
 * possible for strlen() to be used on compile-time strings for use in
 * static initializers (i.e. as a constant expression).
 */
/**
 * strlen - Return count of characters in a NUL-terminated string
 *
 * @p: pointer to NUL-terminated string to count.
 *
 * Do not use this function unless the string length is known at
 * compile-time. When @p is unterminated, this function may crash
 * or return unexpected counts that could lead to memory content
 * exposures. Prefer strnlen().
 *
 * Returns number of characters in @p (NOT including the final NUL).
 *
 */
#define strlen(p)                                                       \
        __builtin_choose_expr(__is_constexpr(__builtin_strlen(p)),      \
                __builtin_strlen(p), __fortify_strlen(p))
__FORTIFY_INLINE __diagnose_as(__builtin_strlen, 1)
__kernel_size_t __fortify_strlen(const char * const POS p)
{
        const size_t p_size = __member_size(p);
        __kernel_size_t ret;

        /* Give up if we don't know how large p is. */
        if (p_size == SIZE_MAX)
                return __underlying_strlen(p);
        ret = strnlen(p, p_size);
        if (p_size <= ret)
                fortify_panic(FORTIFY_FUNC_strlen, FORTIFY_READ, p_size, ret + 1, ret);
        return ret;
}

/* Defined after fortified strnlen() to reuse it. */
extern ssize_t __real_strscpy(char *, const char *, size_t) __RENAME(sized_strscpy);
__FORTIFY_INLINE ssize_t sized_strscpy(char * const POS p, const char * const POS q, size_t size)
{
        /* Use string size rather than possible enclosing struct size. */
        const size_t p_size = __member_size(p);
        const size_t q_size = __member_size(q);
        size_t len;

        /* If we cannot get size of p and q default to call strscpy. */
        if (p_size == SIZE_MAX && q_size == SIZE_MAX)
                return __real_strscpy(p, q, size);

        /*
         * If size can be known at compile time and is greater than
         * p_size, generate a compile time write overflow error.
         */
        if (__compiletime_lessthan(p_size, size))
                __write_overflow();

        /* Short-circuit for compile-time known-safe lengths. */
        if (__compiletime_lessthan(p_size, SIZE_MAX)) {
                len = __compiletime_strlen(q);

                if (len < SIZE_MAX && __compiletime_lessthan(len, size)) {
                        __underlying_memcpy(p, q, len + 1);
                        return len;
                }
        }

        /*
         * This call protects from read overflow, because len will default to q
         * length if it smaller than size.
         */
        len = strnlen(q, size);
        /*
         * If len equals size, we will copy only size bytes which leads to
         * -E2BIG being returned.
         * Otherwise we will copy len + 1 because of the final '\O'.
         */
        len = len == size ? size : len + 1;

        /*
         * Generate a runtime write overflow error if len is greater than
         * p_size.
         */
        if (p_size < len)
                fortify_panic(FORTIFY_FUNC_strscpy, FORTIFY_WRITE, p_size, len, -E2BIG);

        /*
         * We can now safely call vanilla strscpy because we are protected from:
         * 1. Read overflow thanks to call to strnlen().
         * 2. Write overflow thanks to above ifs.
         */
        return __real_strscpy(p, q, len);
}

/* Defined after fortified strlen() to reuse it. */
extern size_t __real_strlcat(char *p, const char *q, size_t avail) __RENAME(strlcat);
/**
 * strlcat - Append a string to an existing string
 *
 * @p: pointer to %NUL-terminated string to append to
 * @q: pointer to %NUL-terminated string to append from
 * @avail: Maximum bytes available in @p
 *
 * Appends %NUL-terminated string @q after the %NUL-terminated
 * string at @p, but will not write beyond @avail bytes total,
 * potentially truncating the copy from @q. @p will stay
 * %NUL-terminated only if a %NUL already existed within
 * the @avail bytes of @p. If so, the resulting number of
 * bytes copied from @q will be at most "@avail - strlen(@p) - 1".
 *
 * Do not use this function. While FORTIFY_SOURCE tries to avoid
 * read and write overflows, this is only possible when the sizes
 * of @p and @q are known to the compiler. Prefer building the
 * string with formatting, via scnprintf(), seq_buf, or similar.
 *
 * Returns total bytes that _would_ have been contained by @p
 * regardless of truncation, similar to snprintf(). If return
 * value is >= @avail, the string has been truncated.
 *
 */
__FORTIFY_INLINE
size_t strlcat(char * const POS p, const char * const POS q, size_t avail)
{
        const size_t p_size = __member_size(p);
        const size_t q_size = __member_size(q);
        size_t p_len, copy_len;
        size_t actual, wanted;

        /* Give up immediately if both buffer sizes are unknown. */
        if (p_size == SIZE_MAX && q_size == SIZE_MAX)
                return __real_strlcat(p, q, avail);

        p_len = strnlen(p, avail);
        copy_len = strlen(q);
        wanted = actual = p_len + copy_len;

        /* Cannot append any more: report truncation. */
        if (avail <= p_len)
                return wanted;

        /* Give up if string is already overflowed. */
        if (p_size <= p_len)
                fortify_panic(FORTIFY_FUNC_strlcat, FORTIFY_READ, p_size, p_len + 1, wanted);

        if (actual >= avail) {
                copy_len = avail - p_len - 1;
                actual = p_len + copy_len;
        }

        /* Give up if copy will overflow. */
        if (p_size <= actual)
                fortify_panic(FORTIFY_FUNC_strlcat, FORTIFY_WRITE, p_size, actual + 1, wanted);
        __underlying_memcpy(p + p_len, q, copy_len);
        p[actual] = '\0';

        return wanted;
}

/* Defined after fortified strlcat() to reuse it. */
/**
 * strcat - Append a string to an existing string
 *
 * @p: pointer to NUL-terminated string to append to
 * @q: pointer to NUL-terminated source string to append from
 *
 * Do not use this function. While FORTIFY_SOURCE tries to avoid
 * read and write overflows, this is only possible when the
 * destination buffer size is known to the compiler. Prefer
 * building the string with formatting, via scnprintf() or similar.
 * At the very least, use strncat().
 *
 * Returns @p.
 *
 */
__FORTIFY_INLINE __diagnose_as(__builtin_strcat, 1, 2)
char *strcat(char * const POS p, const char *q)
{
        const size_t p_size = __member_size(p);
        const size_t wanted = strlcat(p, q, p_size);

        if (p_size <= wanted)
                fortify_panic(FORTIFY_FUNC_strcat, FORTIFY_WRITE, p_size, wanted + 1, p);
        return p;
}

/**
 * strncat - Append a string to an existing string
 *
 * @p: pointer to NUL-terminated string to append to
 * @q: pointer to source string to append from
 * @count: Maximum bytes to read from @q
 *
 * Appends at most @count bytes from @q (stopping at the first
 * NUL byte) after the NUL-terminated string at @p. @p will be
 * NUL-terminated.
 *
 * Do not use this function. While FORTIFY_SOURCE tries to avoid
 * read and write overflows, this is only possible when the sizes
 * of @p and @q are known to the compiler. Prefer building the
 * string with formatting, via scnprintf() or similar.
 *
 * Returns @p.
 *
 */
/* Defined after fortified strlen() and strnlen() to reuse them. */
__FORTIFY_INLINE __diagnose_as(__builtin_strncat, 1, 2, 3)
char *strncat(char * const POS p, const char * const POS q, __kernel_size_t count)
{
        const size_t p_size = __member_size(p);
        const size_t q_size = __member_size(q);
        size_t p_len, copy_len, total;

        if (p_size == SIZE_MAX && q_size == SIZE_MAX)
                return __underlying_strncat(p, q, count);
        p_len = strlen(p);
        copy_len = strnlen(q, count);
        total = p_len + copy_len + 1;
        if (p_size < total)
                fortify_panic(FORTIFY_FUNC_strncat, FORTIFY_WRITE, p_size, total, p);
        __underlying_memcpy(p + p_len, q, copy_len);
        p[p_len + copy_len] = '\0';
        return p;
}

__FORTIFY_INLINE bool fortify_memset_chk(__kernel_size_t size,
                                         const size_t p_size,
                                         const size_t p_size_field)
{
        if (__builtin_constant_p(size)) {
                /*
                 * Length argument is a constant expression, so we
                 * can perform compile-time bounds checking where
                 * buffer sizes are also known at compile time.
                 */

                /* Error when size is larger than enclosing struct. */
                if (__compiletime_lessthan(p_size_field, p_size) &&
                    __compiletime_lessthan(p_size, size))
                        __write_overflow();

                /* Warn when write size is larger than dest field. */
                if (__compiletime_lessthan(p_size_field, size))
                        __write_overflow_field(p_size_field, size);
        }
        /*
         * At this point, length argument may not be a constant expression,
         * so run-time bounds checking can be done where buffer sizes are
         * known. (This is not an "else" because the above checks may only
         * be compile-time warnings, and we want to still warn for run-time
         * overflows.)
         */

        /*
         * Always stop accesses beyond the struct that contains the
         * field, when the buffer's remaining size is known.
         * (The SIZE_MAX test is to optimize away checks where the buffer
         * lengths are unknown.)
         */
        if (p_size != SIZE_MAX && p_size < size)
                fortify_panic(FORTIFY_FUNC_memset, FORTIFY_WRITE, p_size, size, true);
        return false;
}

#define __fortify_memset_chk(p, c, size, p_size, p_size_field) ({       \
        size_t __fortify_size = (size_t)(size);                         \
        fortify_memset_chk(__fortify_size, p_size, p_size_field),       \
        __underlying_memset(p, c, __fortify_size);                      \
})

/*
 * __struct_size() vs __member_size() must be captured here to avoid
 * evaluating argument side-effects further into the macro layers.
 */
#ifndef CONFIG_KMSAN
#define memset(p, c, s) __fortify_memset_chk(p, c, s,                   \
                __struct_size(p), __member_size(p))
#endif

/*
 * To make sure the compiler can enforce protection against buffer overflows,
 * memcpy(), memmove(), and memset() must not be used beyond individual
 * struct members. If you need to copy across multiple members, please use
 * struct_group() to create a named mirror of an anonymous struct union.
 * (e.g. see struct sk_buff.) Read overflow checking is currently only
 * done when a write overflow is also present, or when building with W=1.
 *
 * Mitigation coverage matrix
 *                                      Bounds checking at:
 *                                      +-------+-------+-------+-------+
 *                                      | Compile time  |   Run time    |
 * memcpy() argument sizes:             | write | read  | write | read  |
 *        dest     source   length      +-------+-------+-------+-------+
 * memcpy(known,   known,   constant)   |   y   |   y   |  n/a  |  n/a  |
 * memcpy(known,   unknown, constant)   |   y   |   n   |  n/a  |   V   |
 * memcpy(known,   known,   dynamic)    |   n   |   n   |   B   |   B   |
 * memcpy(known,   unknown, dynamic)    |   n   |   n   |   B   |   V   |
 * memcpy(unknown, known,   constant)   |   n   |   y   |   V   |  n/a  |
 * memcpy(unknown, unknown, constant)   |   n   |   n   |   V   |   V   |
 * memcpy(unknown, known,   dynamic)    |   n   |   n   |   V   |   B   |
 * memcpy(unknown, unknown, dynamic)    |   n   |   n   |   V   |   V   |
 *                                      +-------+-------+-------+-------+
 *
 * y = perform deterministic compile-time bounds checking
 * n = cannot perform deterministic compile-time bounds checking
 * n/a = no run-time bounds checking needed since compile-time deterministic
 * B = can perform run-time bounds checking (currently unimplemented)
 * V = vulnerable to run-time overflow (will need refactoring to solve)
 *
 */
__FORTIFY_INLINE bool fortify_memcpy_chk(__kernel_size_t size,
                                         const size_t p_size,
                                         const size_t q_size,
                                         const size_t p_size_field,
                                         const size_t q_size_field,
                                         const u8 func)
{
        if (__builtin_constant_p(size)) {
                /*
                 * Length argument is a constant expression, so we
                 * can perform compile-time bounds checking where
                 * buffer sizes are also known at compile time.
                 */

                /* Error when size is larger than enclosing struct. */
                if (__compiletime_lessthan(p_size_field, p_size) &&
                    __compiletime_lessthan(p_size, size))
                        __write_overflow();
                if (__compiletime_lessthan(q_size_field, q_size) &&
                    __compiletime_lessthan(q_size, size))
                        __read_overflow2();

                /* Warn when write size argument larger than dest field. */
                if (__compiletime_lessthan(p_size_field, size))
                        __write_overflow_field(p_size_field, size);
                /*
                 * Warn for source field over-read when building with W=1
                 * or when an over-write happened, so both can be fixed at
                 * the same time.
                 */
                if ((IS_ENABLED(KBUILD_EXTRA_WARN1) ||
                     __compiletime_lessthan(p_size_field, size)) &&
                    __compiletime_lessthan(q_size_field, size))
                        __read_overflow2_field(q_size_field, size);
        }
        /*
         * At this point, length argument may not be a constant expression,
         * so run-time bounds checking can be done where buffer sizes are
         * known. (This is not an "else" because the above checks may only
         * be compile-time warnings, and we want to still warn for run-time
         * overflows.)
         */

        /*
         * Always stop accesses beyond the struct that contains the
         * field, when the buffer's remaining size is known.
         * (The SIZE_MAX test is to optimize away checks where the buffer
         * lengths are unknown.)
         */
        if (p_size != SIZE_MAX && p_size < size)
                fortify_panic(func, FORTIFY_WRITE, p_size, size, true);
        else if (q_size != SIZE_MAX && q_size < size)
                fortify_panic(func, FORTIFY_READ, p_size, size, true);

        /*
         * Warn when writing beyond destination field size.
         *
         * Note the implementation of __builtin_*object_size() behaves
         * like sizeof() when not directly referencing a flexible
         * array member, which means there will be many bounds checks
         * that will appear at run-time, without a way for them to be
         * detected at compile-time (as can be done when the destination
         * is specifically the flexible array member).
         * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101832
         */
        if (p_size_field != SIZE_MAX &&
            p_size != p_size_field && p_size_field < size)
                return true;

        return false;
}

#define __fortify_memcpy_chk(p, q, size, p_size, q_size,                \
                             p_size_field, q_size_field, op) ({         \
        const size_t __fortify_size = (size_t)(size);                   \
        const size_t __p_size = (p_size);                               \
        const size_t __q_size = (q_size);                               \
        const size_t __p_size_field = (p_size_field);                   \
        const size_t __q_size_field = (q_size_field);                   \
        fortify_warn_once(fortify_memcpy_chk(__fortify_size, __p_size,  \
                                     __q_size, __p_size_field,          \
                                     __q_size_field, FORTIFY_FUNC_ ##op), \
                  #op ": detected field-spanning write (size %zu) of single %s (size %zu)\n", \
                  __fortify_size,                                       \
                  "field \"" #p "\" at " FILE_LINE,                     \
                  __p_size_field);                                      \
        __underlying_##op(p, q, __fortify_size);                        \
})

/*
 * Notes about compile-time buffer size detection:
 *
 * With these types...
 *
 *      struct middle {
 *              u16 a;
 *              u8 middle_buf[16];
 *              int b;
 *      };
 *      struct end {
 *              u16 a;
 *              u8 end_buf[16];
 *      };
 *      struct flex {
 *              int a;
 *              u8 flex_buf[];
 *      };
 *
 *      void func(TYPE *ptr) { ... }
 *
 * Cases where destination size cannot be currently detected:
 * - the size of ptr's object (seemingly by design, gcc & clang fail):
 *      __builtin_object_size(ptr, 1) == SIZE_MAX
 * - the size of flexible arrays in ptr's obj (by design, dynamic size):
 *      __builtin_object_size(ptr->flex_buf, 1) == SIZE_MAX
 * - the size of ANY array at the end of ptr's obj (gcc and clang bug):
 *      __builtin_object_size(ptr->end_buf, 1) == SIZE_MAX
 *      https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101836
 *
 * Cases where destination size is currently detected:
 * - the size of non-array members within ptr's object:
 *      __builtin_object_size(ptr->a, 1) == 2
 * - the size of non-flexible-array in the middle of ptr's obj:
 *      __builtin_object_size(ptr->middle_buf, 1) == 16
 *
 */

/*
 * __struct_size() vs __member_size() must be captured here to avoid
 * evaluating argument side-effects further into the macro layers.
 */
#define memcpy(p, q, s)  __fortify_memcpy_chk(p, q, s,                  \
                __struct_size(p), __struct_size(q),                     \
                __member_size(p), __member_size(q),                     \
                memcpy)
#define memmove(p, q, s)  __fortify_memcpy_chk(p, q, s,                 \
                __struct_size(p), __struct_size(q),                     \
                __member_size(p), __member_size(q),                     \
                memmove)

extern void *__real_memscan(void *, int, __kernel_size_t) __RENAME(memscan);
__FORTIFY_INLINE void *memscan(void * const POS0 p, int c, __kernel_size_t size)
{
        const size_t p_size = __struct_size(p);

        if (__compiletime_lessthan(p_size, size))
                __read_overflow();
        if (p_size < size)
                fortify_panic(FORTIFY_FUNC_memscan, FORTIFY_READ, p_size, size, NULL);
        return __real_memscan(p, c, size);
}

__FORTIFY_INLINE __diagnose_as(__builtin_memcmp, 1, 2, 3)
int memcmp(const void * const POS0 p, const void * const POS0 q, __kernel_size_t size)
{
        const size_t p_size = __struct_size(p);
        const size_t q_size = __struct_size(q);

        if (__builtin_constant_p(size)) {
                if (__compiletime_lessthan(p_size, size))
                        __read_overflow();
                if (__compiletime_lessthan(q_size, size))
                        __read_overflow2();
        }
        if (p_size < size)
                fortify_panic(FORTIFY_FUNC_memcmp, FORTIFY_READ, p_size, size, INT_MIN);
        else if (q_size < size)
                fortify_panic(FORTIFY_FUNC_memcmp, FORTIFY_READ, q_size, size, INT_MIN);
        return __underlying_memcmp(p, q, size);
}

__FORTIFY_INLINE __diagnose_as(__builtin_memchr, 1, 2, 3)
void *memchr(const void * const POS0 p, int c, __kernel_size_t size)
{
        const size_t p_size = __struct_size(p);

        if (__compiletime_lessthan(p_size, size))
                __read_overflow();
        if (p_size < size)
                fortify_panic(FORTIFY_FUNC_memchr, FORTIFY_READ, p_size, size, NULL);
        return __underlying_memchr(p, c, size);
}

void *__real_memchr_inv(const void *s, int c, size_t n) __RENAME(memchr_inv);
__FORTIFY_INLINE void *memchr_inv(const void * const POS0 p, int c, size_t size)
{
        const size_t p_size = __struct_size(p);

        if (__compiletime_lessthan(p_size, size))
                __read_overflow();
        if (p_size < size)
                fortify_panic(FORTIFY_FUNC_memchr_inv, FORTIFY_READ, p_size, size, NULL);
        return __real_memchr_inv(p, c, size);
}

extern void *__real_kmemdup(const void *src, size_t len, gfp_t gfp) __RENAME(kmemdup_noprof)
                                                                    __realloc_size(2);
__FORTIFY_INLINE void *kmemdup_noprof(const void * const POS0 p, size_t size, gfp_t gfp)
{
        const size_t p_size = __struct_size(p);

        if (__compiletime_lessthan(p_size, size))
                __read_overflow();
        if (p_size < size)
                fortify_panic(FORTIFY_FUNC_kmemdup, FORTIFY_READ, p_size, size,
                              __real_kmemdup(p, 0, gfp));
        return __real_kmemdup(p, size, gfp);
}
#define kmemdup(...)    alloc_hooks(kmemdup_noprof(__VA_ARGS__))

/**
 * strcpy - Copy a string into another string buffer
 *
 * @p: pointer to destination of copy
 * @q: pointer to NUL-terminated source string to copy
 *
 * Do not use this function. While FORTIFY_SOURCE tries to avoid
 * overflows, this is only possible when the sizes of @q and @p are
 * known to the compiler. Prefer strscpy(), though note its different
 * return values for detecting truncation.
 *
 * Returns @p.
 *
 */
/* Defined after fortified strlen to reuse it. */
__FORTIFY_INLINE __diagnose_as(__builtin_strcpy, 1, 2)
char *strcpy(char * const POS p, const char * const POS q)
{
        const size_t p_size = __member_size(p);
        const size_t q_size = __member_size(q);
        size_t size;

        /* If neither buffer size is known, immediately give up. */
        if (__builtin_constant_p(p_size) &&
            __builtin_constant_p(q_size) &&
            p_size == SIZE_MAX && q_size == SIZE_MAX)
                return __underlying_strcpy(p, q);
        size = strlen(q) + 1;
        /* Compile-time check for const size overflow. */
        if (__compiletime_lessthan(p_size, size))
                __write_overflow();
        /* Run-time check for dynamic size overflow. */
        if (p_size < size)
                fortify_panic(FORTIFY_FUNC_strcpy, FORTIFY_WRITE, p_size, size, p);
        __underlying_memcpy(p, q, size);
        return p;
}

/* Don't use these outside the FORITFY_SOURCE implementation */
#undef __underlying_memchr
#undef __underlying_memcmp
#undef __underlying_strcat
#undef __underlying_strcpy
#undef __underlying_strlen
#undef __underlying_strncat
#undef __underlying_strncpy

#undef POS
#undef POS0

#endif /* _LINUX_FORTIFY_STRING_H_ */