diff mbox series

[bpf-next,v2,14/15] bpf: allow '?' at the beginning of DATASEC names

Message ID 20240302011920.15302-15-eddyz87@gmail.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series libbpf: type suffixes and autocreate flag for struct_ops maps | expand

Checks

Context Check Description
bpf/vmtest-bpf-next-PR fail PR summary
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1054 this patch: 1054
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers warning 6 maintainers not CCed: jolsa@kernel.org john.fastabend@gmail.com kpsingh@kernel.org song@kernel.org sdf@google.com haoluo@google.com
netdev/build_clang success Errors and warnings before: 1066 this patch: 1066
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1071 this patch: 1071
netdev/checkpatch warning WARNING: line length of 81 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
bpf/vmtest-bpf-next-VM_Test-16 success Logs for s390x-gcc / test (test_verifier, false, 360) / test_verifier on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-21 success Logs for x86_64-gcc / test (test_maps, false, 360) / test_maps on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-24 success Logs for x86_64-gcc / test (test_progs_no_alu32_parallel, true, 30) / test_progs_no_alu32_parallel on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-25 success Logs for x86_64-gcc / test (test_progs_parallel, true, 30) / test_progs_parallel on x86_64 with gcc
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bpf/vmtest-bpf-next-VM_Test-33 fail Logs for x86_64-llvm-18 / build-release / build for x86_64 with llvm-18 and -O2 optimization

Commit Message

Eduard Zingerman March 2, 2024, 1:19 a.m. UTC
Currently kernel does not allow question marks in BTF names.
This commit makes an exception, allowing first character of the
DATASEC name to be a question mark.

The intent is to allow libbpf to use SEC("?.struct_ops") to identify
struct_ops maps that are optional, e.g. like in the following BPF code:

    SEC("?.struct_ops")
    struct test_ops optional_map = { ... };

Which yields the following BTF:

    ...
    [13] DATASEC '?.struct_ops' size=0 vlen=...
    ...

To load such BTF libbpf rewrites DATASEC name before load.
After this patch the rewrite won't be necessary.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
---
 kernel/bpf/btf.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)
diff mbox series

Patch

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 6ff0bd1a91d5..a25fb6bce808 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -761,12 +761,13 @@  static bool btf_name_offset_valid(const struct btf *btf, u32 offset)
 	return offset < btf->hdr.str_len;
 }
 
-static bool __btf_name_char_ok(char c, bool first)
+static bool __btf_name_char_ok(char c, bool first, bool allow_qmark)
 {
 	if ((first ? !isalpha(c) :
 		     !isalnum(c)) &&
 	    c != '_' &&
-	    c != '.')
+	    c != '.' &&
+	    (allow_qmark && first ? c != '?' : true))
 		return false;
 	return true;
 }
@@ -783,20 +784,20 @@  static const char *btf_str_by_offset(const struct btf *btf, u32 offset)
 	return NULL;
 }
 
-static bool __btf_name_valid(const struct btf *btf, u32 offset)
+static bool __btf_name_valid(const struct btf *btf, u32 offset, bool allow_qmark)
 {
 	/* offset must be valid */
 	const char *src = btf_str_by_offset(btf, offset);
 	const char *src_limit;
 
-	if (!__btf_name_char_ok(*src, true))
+	if (!__btf_name_char_ok(*src, true, allow_qmark))
 		return false;
 
 	/* set a limit on identifier length */
 	src_limit = src + KSYM_NAME_LEN;
 	src++;
 	while (*src && src < src_limit) {
-		if (!__btf_name_char_ok(*src, false))
+		if (!__btf_name_char_ok(*src, false, false))
 			return false;
 		src++;
 	}
@@ -806,12 +807,12 @@  static bool __btf_name_valid(const struct btf *btf, u32 offset)
 
 static bool btf_name_valid_identifier(const struct btf *btf, u32 offset)
 {
-	return __btf_name_valid(btf, offset);
+	return __btf_name_valid(btf, offset, false);
 }
 
 static bool btf_name_valid_section(const struct btf *btf, u32 offset)
 {
-	return __btf_name_valid(btf, offset);
+	return __btf_name_valid(btf, offset, true);
 }
 
 static const char *__btf_name_by_offset(const struct btf *btf, u32 offset)
@@ -4481,7 +4482,7 @@  static s32 btf_var_check_meta(struct btf_verifier_env *env,
 	}
 
 	if (!t->name_off ||
-	    !__btf_name_valid(env->btf, t->name_off)) {
+	    !btf_name_valid_identifier(env->btf, t->name_off)) {
 		btf_verifier_log_type(env, t, "Invalid name");
 		return -EINVAL;
 	}