Commit 19559e84 authored by Rong Tao's avatar Rong Tao Committed by Alexei Starovoitov
Browse files

bpf: add bpf_strcasecmp kfunc 



bpf_strcasecmp() function performs same like bpf_strcmp() except ignoring
the case of the characters.

Signed-off-by: default avatarRong Tao <rongtao@cestc.cn>
Acked-by: default avatarYonghong Song <yonghong.song@linux.dev>
Acked-by: default avatarViktor Malik <vmalik@redhat.com>
Link: https://lore.kernel.org/r/tencent_292BD3682A628581AA904996D8E59F4ACD06@qq.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 525ac69b

kernel/bpf/helpers.c

+48 −20
Original line number Diff line number Diff line
@@ -3349,45 +3349,72 @@ __bpf_kfunc void __bpf_trap(void) 
 * __get_kernel_nofault instead of plain dereference to make them safe.

 */



/**

 * bpf_strcmp - Compare two strings

 * @s1__ign: One string

 * @s2__ign: Another string

 *

 * Return:

 * * %0       - Strings are equal

 * * %-1      - @s1__ign is smaller

 * * %1       - @s2__ign is smaller

 * * %-EFAULT - Cannot read one of the strings

 * * %-E2BIG  - One of strings is too large

 * * %-ERANGE - One of strings is outside of kernel address space

 */

__bpf_kfunc int bpf_strcmp(const char *s1__ign, const char *s2__ign)

static int __bpf_strcasecmp(const char *s1, const char *s2, bool ignore_case)

{

	char c1, c2;

	int i;



	if (!copy_from_kernel_nofault_allowed(s1__ign, 1) ||

	    !copy_from_kernel_nofault_allowed(s2__ign, 1)) {

	if (!copy_from_kernel_nofault_allowed(s1, 1) ||

	    !copy_from_kernel_nofault_allowed(s2, 1)) {

		return -ERANGE;

	}



	guard(pagefault)();

	for (i = 0; i < XATTR_SIZE_MAX; i++) {

		__get_kernel_nofault(&c1, s1__ign, char, err_out);

		__get_kernel_nofault(&c2, s2__ign, char, err_out);

		__get_kernel_nofault(&c1, s1, char, err_out);

		__get_kernel_nofault(&c2, s2, char, err_out);

		if (ignore_case) {

			c1 = tolower(c1);

			c2 = tolower(c2);

		}

		if (c1 != c2)

			return c1 < c2 ? -1 : 1;

		if (c1 == '\0')

			return 0;

		s1__ign++;

		s2__ign++;

		s1++;

		s2++;

	}

	return -E2BIG;

err_out:

	return -EFAULT;

}



/**

 * bpf_strcmp - Compare two strings

 * @s1__ign: One string

 * @s2__ign: Another string

 *

 * Return:

 * * %0       - Strings are equal

 * * %-1      - @s1__ign is smaller

 * * %1       - @s2__ign is smaller

 * * %-EFAULT - Cannot read one of the strings

 * * %-E2BIG  - One of strings is too large

 * * %-ERANGE - One of strings is outside of kernel address space

 */

__bpf_kfunc int bpf_strcmp(const char *s1__ign, const char *s2__ign)

{

	return __bpf_strcasecmp(s1__ign, s2__ign, false);

}



/**

 * bpf_strcasecmp - Compare two strings, ignoring the case of the characters

 * @s1__ign: One string

 * @s2__ign: Another string

 *

 * Return:

 * * %0       - Strings are equal

 * * %-1      - @s1__ign is smaller

 * * %1       - @s2__ign is smaller

 * * %-EFAULT - Cannot read one of the strings

 * * %-E2BIG  - One of strings is too large

 * * %-ERANGE - One of strings is outside of kernel address space

 */

__bpf_kfunc int bpf_strcasecmp(const char *s1__ign, const char *s2__ign)

{

	return __bpf_strcasecmp(s1__ign, s2__ign, true);

}



/**

 * bpf_strnchr - Find a character in a length limited string

 * @s__ign: The string to be searched
@@ -3832,6 +3859,7 @@ BTF_ID_FLAGS(func, bpf_iter_dmabuf_destroy, KF_ITER_DESTROY | KF_SLEEPABLE) 
#endif

BTF_ID_FLAGS(func, __bpf_trap)

BTF_ID_FLAGS(func, bpf_strcmp);

BTF_ID_FLAGS(func, bpf_strcasecmp);

BTF_ID_FLAGS(func, bpf_strchr);

BTF_ID_FLAGS(func, bpf_strchrnul);

BTF_ID_FLAGS(func, bpf_strnchr);