diff mbox series

[bpf-next,v2,1/4] bpf: add bpf_strncmp helper

Message ID 20211210141652.877186-2-houtao1@huawei.com (mailing list archive)
State Accepted
Delegated to: BPF
Headers show
Series introduce bpf_strncmp() helper | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for bpf-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 12484 this patch: 12484
netdev/cc_maintainers warning 4 maintainers not CCed: kpsingh@kernel.org songliubraving@fb.com john.fastabend@gmail.com joe@cilium.io
netdev/build_clang success Errors and warnings before: 2106 this patch: 2106
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 11650 this patch: 11650
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 81 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Hou Tao Dec. 10, 2021, 2:16 p.m. UTC 
The helper compares two strings: one string is a null-terminated
read-only string, and another string has const max storage size
but doesn't need to be null-terminated. It can be used to compare
file name in tracing or LSM program.

Signed-off-by: Hou Tao <houtao1@huawei.com>
---
 include/linux/bpf.h            |  1 +
 include/uapi/linux/bpf.h       | 11 +++++++++++
 kernel/bpf/helpers.c           | 16 ++++++++++++++++
 tools/include/uapi/linux/bpf.h | 11 +++++++++++
 4 files changed, 39 insertions(+)
diff mbox series

Patch

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 8bbf08fbab66..6b7c533ba249 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2173,6 +2173,7 @@  extern const struct bpf_func_proto bpf_sk_getsockopt_proto;
 extern const struct bpf_func_proto bpf_kallsyms_lookup_name_proto;
 extern const struct bpf_func_proto bpf_find_vma_proto;
 extern const struct bpf_func_proto bpf_loop_proto;
+extern const struct bpf_func_proto bpf_strncmp_proto;
 
 const struct bpf_func_proto *tracing_prog_func_proto(
   enum bpf_func_id func_id, const struct bpf_prog *prog);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index c26871263f1f..2820c77e4846 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -4983,6 +4983,16 @@  union bpf_attr {
  *	Return
  *		The number of loops performed, **-EINVAL** for invalid **flags**,
  *		**-E2BIG** if **nr_loops** exceeds the maximum number of loops.
+ *
+ * long bpf_strncmp(const char *s1, u32 s1_sz, const char *s2)
+ *	Description
+ *		Do strncmp() between **s1** and **s2**. **s1** doesn't need
+ *		to be null-terminated and **s1_sz** is the maximum storage
+ *		size of **s1**. **s2** must be a read-only string.
+ *	Return
+ *		An integer less than, equal to, or greater than zero
+ *		if the first **s1_sz** bytes of **s1** is found to be
+ *		less than, to match, or be greater than **s2**.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -5167,6 +5177,7 @@  union bpf_attr {
 	FN(kallsyms_lookup_name),	\
 	FN(find_vma),			\
 	FN(loop),			\
+	FN(strncmp),			\
 	/* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 52188004a9c3..2b035c03624f 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -565,6 +565,20 @@  const struct bpf_func_proto bpf_strtoul_proto = {
 };
 #endif
 
+BPF_CALL_3(bpf_strncmp, const char *, s1, u32, s1_sz, const char *, s2)
+{
+	return strncmp(s1, s2, s1_sz);
+}
+
+const struct bpf_func_proto bpf_strncmp_proto = {
+	.func		= bpf_strncmp,
+	.gpl_only	= false,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_CONST_SIZE,
+	.arg3_type	= ARG_PTR_TO_CONST_STR,
+};
+
 BPF_CALL_4(bpf_get_ns_current_pid_tgid, u64, dev, u64, ino,
 	   struct bpf_pidns_info *, nsdata, u32, size)
 {
@@ -1380,6 +1394,8 @@  bpf_base_func_proto(enum bpf_func_id func_id)
 		return &bpf_for_each_map_elem_proto;
 	case BPF_FUNC_loop:
 		return &bpf_loop_proto;
+	case BPF_FUNC_strncmp:
+		return &bpf_strncmp_proto;
 	default:
 		break;
 	}
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index c26871263f1f..2820c77e4846 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -4983,6 +4983,16 @@  union bpf_attr {
  *	Return
  *		The number of loops performed, **-EINVAL** for invalid **flags**,
  *		**-E2BIG** if **nr_loops** exceeds the maximum number of loops.
+ *
+ * long bpf_strncmp(const char *s1, u32 s1_sz, const char *s2)
+ *	Description
+ *		Do strncmp() between **s1** and **s2**. **s1** doesn't need
+ *		to be null-terminated and **s1_sz** is the maximum storage
+ *		size of **s1**. **s2** must be a read-only string.
+ *	Return
+ *		An integer less than, equal to, or greater than zero
+ *		if the first **s1_sz** bytes of **s1** is found to be
+ *		less than, to match, or be greater than **s2**.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -5167,6 +5177,7 @@  union bpf_attr {
 	FN(kallsyms_lookup_name),	\
 	FN(find_vma),			\
 	FN(loop),			\
+	FN(strncmp),			\
 	/* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper