Commit 1dc66964 authored by Yuzuki Ishiyama's avatar Yuzuki Ishiyama Committed by Alexei Starovoitov
Browse files

bpf: add bpf_strncasecmp kfunc 



bpf_strncasecmp() function performs same like bpf_strcasecmp() except
limiting the comparison to a specific length.

Signed-off-by: default avatarYuzuki Ishiyama <ishiyama@hpc.is.uec.ac.jp>
Acked-by: default avatarViktor Malik <vmalik@redhat.com>
Acked-by: default avatarMykyta Yatsenko <mykyta.yatsenko5@gmail.com>
Link: https://lore.kernel.org/r/20260121033328.1850010-2-ishiyama@hpc.is.uec.ac.jp


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent d0f5d4f8

kernel/bpf/helpers.c

+25 −5
Original line number Diff line number Diff line
@@ -3413,7 +3413,7 @@ __bpf_kfunc void __bpf_trap(void) 
 * __get_kernel_nofault instead of plain dereference to make them safe.

 */



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

static int __bpf_strncasecmp(const char *s1, const char *s2, bool ignore_case, size_t len)

{

	char c1, c2;

	int i;
@@ -3424,7 +3424,7 @@ static int __bpf_strcasecmp(const char *s1, const char *s2, bool ignore_case) 
	}



	guard(pagefault)();

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

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

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

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

		if (ignore_case) {
@@ -3438,7 +3438,7 @@ static int __bpf_strcasecmp(const char *s1, const char *s2, bool ignore_case) 
		s1++;

		s2++;

	}

	return -E2BIG;

	return i == XATTR_SIZE_MAX ? -E2BIG : 0;

err_out:

	return -EFAULT;

}
@@ -3458,7 +3458,7 @@ static int __bpf_strcasecmp(const char *s1, const char *s2, bool ignore_case) 
 */

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

{

	return __bpf_strcasecmp(s1__ign, s2__ign, false);

	return __bpf_strncasecmp(s1__ign, s2__ign, false, XATTR_SIZE_MAX);

}



/**
@@ -3476,7 +3476,26 @@ __bpf_kfunc int bpf_strcmp(const char *s1__ign, const char *s2__ign) 
 */

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

{

	return __bpf_strcasecmp(s1__ign, s2__ign, true);

	return __bpf_strncasecmp(s1__ign, s2__ign, true, XATTR_SIZE_MAX);

}



/*

 * bpf_strncasecmp - Compare two length-limited strings, ignoring case

 * @s1__ign: One string

 * @s2__ign: Another string

 * @len: The maximum number of characters to compare

 *

 * 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_strncasecmp(const char *s1__ign, const char *s2__ign, size_t len)

{

	return __bpf_strncasecmp(s1__ign, s2__ign, true, len);

}



/**
@@ -4526,6 +4545,7 @@ BTF_ID_FLAGS(func, bpf_iter_dmabuf_destroy, KF_ITER_DESTROY | KF_SLEEPABLE) 
BTF_ID_FLAGS(func, __bpf_trap)

BTF_ID_FLAGS(func, bpf_strcmp);

BTF_ID_FLAGS(func, bpf_strcasecmp);

BTF_ID_FLAGS(func, bpf_strncasecmp);

BTF_ID_FLAGS(func, bpf_strchr);

BTF_ID_FLAGS(func, bpf_strchrnul);

BTF_ID_FLAGS(func, bpf_strnchr);