Commit d73cbe2c authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

Merge branch 'bpf-add-kfunc-bpf_strncasecmp' 

Yuzuki Ishiyama says:

====================
bpf: Add kfunc bpf_strncasecmp()

This patchset introduces bpf_strncasecmp to allow case-insensitive and
limited-length string comparison. This is useful for parsing protocol
headers like HTTP.
---

Changes in v5:
- Fixed the test function numbering

Changes in v4:
- Updated the loop variable to maintain style consistency

Changes in v3:
- Use ternary operator to maintain style consistency
- Reverted unnecessary doc comment about XATTR_SIZE_MAX

Changes in v2:
- Compute max_sz upfront and remove len check from the loop body
- Document that @len is limited by XATTR_SIZE_MAX
====================

Link: https://patch.msgid.link/20260121033328.1850010-1-ishiyama@hpc.is.uec.ac.jp


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents d0f5d4f8 f4924ad0

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);

tools/testing/selftests/bpf/prog_tests/string_kfuncs.c

+1 −0
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 
static const char * const test_cases[] = {

	"strcmp",

	"strcasecmp",

	"strncasecmp",

	"strchr",

	"strchrnul",

	"strnchr",

tools/testing/selftests/bpf/progs/string_kfuncs_failure1.c

+6 −0
Original line number Diff line number Diff line
@@ -33,6 +33,8 @@ SEC("syscall") __retval(USER_PTR_ERR) int test_strcmp_null1(void *ctx) { return 
SEC("syscall")  __retval(USER_PTR_ERR)int test_strcmp_null2(void *ctx) { return bpf_strcmp("hello", NULL); }

SEC("syscall") __retval(USER_PTR_ERR) int test_strcasecmp_null1(void *ctx) { return bpf_strcasecmp(NULL, "HELLO"); }

SEC("syscall")  __retval(USER_PTR_ERR)int test_strcasecmp_null2(void *ctx) { return bpf_strcasecmp("HELLO", NULL); }

SEC("syscall") __retval(USER_PTR_ERR)int test_strncasecmp_null1(void *ctx) { return bpf_strncasecmp(NULL, "HELLO", 5); }

SEC("syscall")  __retval(USER_PTR_ERR)int test_strncasecmp_null2(void *ctx) { return bpf_strncasecmp("HELLO", NULL, 5);	 }

SEC("syscall")  __retval(USER_PTR_ERR)int test_strchr_null(void *ctx) { return bpf_strchr(NULL, 'a'); }

SEC("syscall")  __retval(USER_PTR_ERR)int test_strchrnul_null(void *ctx) { return bpf_strchrnul(NULL, 'a'); }

SEC("syscall")  __retval(USER_PTR_ERR)int test_strnchr_null(void *ctx) { return bpf_strnchr(NULL, 1, 'a'); }
@@ -57,6 +59,8 @@ SEC("syscall") __retval(USER_PTR_ERR) int test_strcmp_user_ptr1(void *ctx) { ret 
SEC("syscall") __retval(USER_PTR_ERR) int test_strcmp_user_ptr2(void *ctx) { return bpf_strcmp("hello", user_ptr); }

SEC("syscall") __retval(USER_PTR_ERR) int test_strcasecmp_user_ptr1(void *ctx) { return bpf_strcasecmp(user_ptr, "HELLO"); }

SEC("syscall") __retval(USER_PTR_ERR) int test_strcasecmp_user_ptr2(void *ctx) { return bpf_strcasecmp("HELLO", user_ptr); }

SEC("syscall") __retval(USER_PTR_ERR) int test_strncasecmp_user_ptr1(void *ctx) { return bpf_strncasecmp(user_ptr, "HELLO", 5); }

SEC("syscall") __retval(USER_PTR_ERR) int test_strncasecmp_user_ptr2(void *ctx) { return bpf_strncasecmp("HELLO", user_ptr, 5);	 }

SEC("syscall") __retval(USER_PTR_ERR) int test_strchr_user_ptr(void *ctx) { return bpf_strchr(user_ptr, 'a'); }

SEC("syscall") __retval(USER_PTR_ERR) int test_strchrnul_user_ptr(void *ctx) { return bpf_strchrnul(user_ptr, 'a'); }

SEC("syscall") __retval(USER_PTR_ERR) int test_strnchr_user_ptr(void *ctx) { return bpf_strnchr(user_ptr, 1, 'a'); }
@@ -83,6 +87,8 @@ SEC("syscall") __retval(-EFAULT) int test_strcmp_pagefault1(void *ctx) { return 
SEC("syscall") __retval(-EFAULT) int test_strcmp_pagefault2(void *ctx) { return bpf_strcmp("hello", invalid_kern_ptr); }

SEC("syscall") __retval(-EFAULT) int test_strcasecmp_pagefault1(void *ctx) { return bpf_strcasecmp(invalid_kern_ptr, "HELLO"); }

SEC("syscall") __retval(-EFAULT) int test_strcasecmp_pagefault2(void *ctx) { return bpf_strcasecmp("HELLO", invalid_kern_ptr); }

SEC("syscall") __retval(-EFAULT) int test_strncasecmp_pagefault1(void *ctx) { return bpf_strncasecmp(invalid_kern_ptr, "HELLO", 5); }

SEC("syscall") __retval(-EFAULT) int test_strncasecmp_pagefault2(void *ctx) { return bpf_strncasecmp("HELLO", invalid_kern_ptr, 5);	 }

SEC("syscall") __retval(-EFAULT) int test_strchr_pagefault(void *ctx) { return bpf_strchr(invalid_kern_ptr, 'a'); }

SEC("syscall") __retval(-EFAULT) int test_strchrnul_pagefault(void *ctx) { return bpf_strchrnul(invalid_kern_ptr, 'a'); }

SEC("syscall") __retval(-EFAULT) int test_strnchr_pagefault(void *ctx) { return bpf_strnchr(invalid_kern_ptr, 1, 'a'); }

tools/testing/selftests/bpf/progs/string_kfuncs_failure2.c

+1 −0
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ char long_str[XATTR_SIZE_MAX + 1]; 


SEC("syscall") int test_strcmp_too_long(void *ctx) { return bpf_strcmp(long_str, long_str); }

SEC("syscall") int test_strcasecmp_too_long(void *ctx) { return bpf_strcasecmp(long_str, long_str); }

SEC("syscall") int test_strncasecmp_too_long(void *ctx) { return bpf_strncasecmp(long_str, long_str, sizeof(long_str)); }

SEC("syscall") int test_strchr_too_long(void *ctx) { return bpf_strchr(long_str, 'b'); }

SEC("syscall") int test_strchrnul_too_long(void *ctx) { return bpf_strchrnul(long_str, 'b'); }

SEC("syscall") int test_strnchr_too_long(void *ctx) { return bpf_strnchr(long_str, sizeof(long_str), 'b'); }

tools/testing/selftests/bpf/progs/string_kfuncs_success.c

+7 −0
Original line number Diff line number Diff line
@@ -17,6 +17,13 @@ __test(0) int test_strcasecmp_eq2(void *ctx) { return bpf_strcasecmp(str, "HELLO 
__test(0) int test_strcasecmp_eq3(void *ctx) { return bpf_strcasecmp(str, "HELLO world"); }

__test(1) int test_strcasecmp_neq1(void *ctx) { return bpf_strcasecmp(str, "hello"); }

__test(1) int test_strcasecmp_neq2(void *ctx) { return bpf_strcasecmp(str, "HELLO"); }

__test(0) int test_strncasecmp_eq1(void *ctx) { return bpf_strncasecmp(str, "hello world", 11); }

__test(0) int test_strncasecmp_eq2(void *ctx) { return bpf_strncasecmp(str, "HELLO WORLD", 11); }

__test(0) int test_strncasecmp_eq3(void *ctx) { return bpf_strncasecmp(str, "HELLO world", 11); }

__test(0) int test_strncasecmp_eq4(void *ctx) { return bpf_strncasecmp(str, "hello", 5); }

__test(0) int test_strncasecmp_eq5(void *ctx) { return bpf_strncasecmp(str, "hello world!", 11); }

__test(-1) int test_strncasecmp_neq1(void *ctx) { return bpf_strncasecmp(str, "hello!", 6); }

__test(1) int test_strncasecmp_neq2(void *ctx) { return bpf_strncasecmp(str, "abc", 3); }

__test(1) int test_strchr_found(void *ctx) { return bpf_strchr(str, 'e'); }

__test(11) int test_strchr_null(void *ctx) { return bpf_strchr(str, '\0'); }

__test(-ENOENT) int test_strchr_notfound(void *ctx) { return bpf_strchr(str, 'x'); }