Re: [PATCH bpf-next v3 1/2] bpf: add bpf_strcasecmp kfunc

On 9/2/25 2:19 AM, Rong Tao wrote:

From: Rong Tao rongtao@cestc.cn

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

Signed-off-by: Rong Tao rongtao@cestc.cn

kernel/bpf/helpers.c | 68 +++++++++++++++++++++++++++++++------------- 1 file changed, 48 insertions(+), 20 deletions(-)

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 401b4932cc49..238fd992c786 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -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) +int __bpf_strcasecmp(const char *s1, const char *s2, bool ignore_case)

The function __bpf_strcasecmp should be a static function.

{ 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);