bpf: Add kfunc bpf_strcasecmp()

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)
 {
 	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);

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

@@ -8,6 +8,7 @@
 
 static const char * const test_cases[] = {
 	"strcmp",
+	"strcasecmp",
 	"strchr",
 	"strchrnul",
 	"strnchr",

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

@@ -31,6 +31,8 @@ char *invalid_kern_ptr = (char *)-1;
 /* Passing NULL to string kfuncs (treated as a userspace ptr) */
 SEC("syscall") __retval(USER_PTR_ERR) int test_strcmp_null1(void *ctx) { return bpf_strcmp(NULL, "hello"); }
 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_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'); }
@@ -49,6 +51,8 @@ SEC("syscall")  __retval(USER_PTR_ERR)int test_strnstr_null2(void *ctx) { return
 /* Passing userspace ptr to string kfuncs */
 SEC("syscall") __retval(USER_PTR_ERR) int test_strcmp_user_ptr1(void *ctx) { return bpf_strcmp(user_ptr, "hello"); }
 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_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'); }
@@ -69,6 +73,8 @@ SEC("syscall") __retval(USER_PTR_ERR) int test_strnstr_user_ptr2(void *ctx) { re
 /* Passing invalid kernel ptr to string kfuncs should always return -EFAULT */
 SEC("syscall") __retval(-EFAULT) int test_strcmp_pagefault1(void *ctx) { return bpf_strcmp(invalid_kern_ptr, "hello"); }
 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_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

@@ -7,6 +7,7 @@
 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_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

@@ -12,6 +12,11 @@ char str[] = "hello world";
 /* Functional tests */
 __test(0) int test_strcmp_eq(void *ctx) { return bpf_strcmp(str, "hello world"); }
 __test(1) int test_strcmp_neq(void *ctx) { return bpf_strcmp(str, "hello"); }
+__test(0) int test_strcasecmp_eq1(void *ctx) { return bpf_strcasecmp(str, "hello world"); }
+__test(0) int test_strcasecmp_eq2(void *ctx) { return bpf_strcasecmp(str, "HELLO WORLD"); }
+__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(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'); }