diff mbox series

[bpf,v2,2/5] bpf: Adjust sk size check for sk in bpf_skb_is_valid_access for CO_RE in 32-bit arch

Message ID 20221107092032.178235-3-yangjihong1@huawei.com (mailing list archive)
State Changes Requested
Delegated to: BPF
Headers show
Series bpf: Support kernel function call in 32-bit ARM | expand

Checks

Context Check Description
bpf/vmtest-bpf-VM_Test-22 success Logs for test_verifier on s390x with gcc
bpf/vmtest-bpf-VM_Test-10 fail Logs for test_progs on s390x with gcc
bpf/vmtest-bpf-VM_Test-13 fail Logs for test_progs_no_alu32 on s390x with gcc
bpf/vmtest-bpf-VM_Test-16 success Logs for test_progs_no_alu32_parallel on s390x with gcc
bpf/vmtest-bpf-VM_Test-19 success Logs for test_progs_parallel on s390x with gcc
netdev/tree_selection success Clearly marked for bpf
netdev/fixes_present fail Series targets non-next tree, but doesn't contain any Fixes tags
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: 23 this patch: 23
netdev/cc_maintainers success CCed 17 of 17 maintainers
netdev/build_clang success Errors and warnings before: 5 this patch: 5
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
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: 23 this patch: 23
netdev/checkpatch warning WARNING: line length of 81 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
bpf/vmtest-bpf-PR fail PR summary
bpf/vmtest-bpf-VM_Test-7 success Logs for test_maps on s390x with gcc
bpf/vmtest-bpf-VM_Test-3 success Logs for build for x86_64 with gcc
bpf/vmtest-bpf-VM_Test-4 success Logs for build for x86_64 with llvm-16
bpf/vmtest-bpf-VM_Test-2 success Logs for build for s390x with gcc
bpf/vmtest-bpf-VM_Test-8 success Logs for test_maps on x86_64 with gcc
bpf/vmtest-bpf-VM_Test-9 success Logs for test_maps on x86_64 with llvm-16
bpf/vmtest-bpf-VM_Test-14 fail Logs for test_progs_no_alu32 on x86_64 with gcc
bpf/vmtest-bpf-VM_Test-15 fail Logs for test_progs_no_alu32 on x86_64 with llvm-16
bpf/vmtest-bpf-VM_Test-17 success Logs for test_progs_no_alu32_parallel on x86_64 with gcc
bpf/vmtest-bpf-VM_Test-18 success Logs for test_progs_no_alu32_parallel on x86_64 with llvm-16
bpf/vmtest-bpf-VM_Test-20 success Logs for test_progs_parallel on x86_64 with gcc
bpf/vmtest-bpf-VM_Test-23 success Logs for test_verifier on x86_64 with gcc
bpf/vmtest-bpf-VM_Test-24 success Logs for test_verifier on x86_64 with llvm-16
bpf/vmtest-bpf-VM_Test-11 fail Logs for test_progs on x86_64 with gcc
bpf/vmtest-bpf-VM_Test-12 fail Logs for test_progs on x86_64 with llvm-16
bpf/vmtest-bpf-VM_Test-21 success Logs for test_progs_parallel on x86_64 with llvm-16
bpf/vmtest-bpf-VM_Test-1 pending Logs for ShellCheck
bpf/vmtest-bpf-VM_Test-5 success Logs for llvm-toolchain
bpf/vmtest-bpf-VM_Test-6 success Logs for set-matrix

Commit Message

Yang Jihong Nov. 7, 2022, 9:20 a.m. UTC 
The error code -EACCES is returned when bpf prog is tested in 32-bit arch.
This is because bpf_object__relocate modifies instruction to change memory
size to 4 bytes, as shown in the following messages:

libbpf: prog 'kfunc_call_test1': relo #2: matching candidate #0 <byte_off> [18342] struct __sk_buff.sk (0:30:0 @ offset 168)
libbpf: prog 'kfunc_call_test1': relo #2: patched insn #1 (LDX/ST/STX) off 168 -> 168
libbpf: prog 'kfunc_call_test1': relo #2: patched insn #1 (LDX/ST/STX) mem_sz 8 -> 4

As a result, the bpf_skb_is_valid_access check fails, for 32-bit arch,
adjust check sk size.

Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
---
 net/core/filter.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/net/core/filter.c b/net/core/filter.c
index bb0136e7a8e4..47cbad2e609f 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -8269,7 +8269,13 @@  static bool bpf_skb_is_valid_access(int off, int size, enum bpf_access_type type
 			return false;
 		break;
 	case offsetof(struct __sk_buff, sk):
-		if (type == BPF_WRITE || size != sizeof(__u64))
+		/* CO_RE adjusts pointer accesses from 8-byte read to
+		 * 4-byte reads in 32-bit host arch, so 32-bit can only
+		 * read the 32-bit pointer or the full 64-bit value,
+		 * and 64-bit can read write the 64-bit pointer.
+		 */
+		if (type == BPF_WRITE ||
+		    (size != sizeof(struct bpf_sock *) && size != sizeof(__u64)))
 			return false;
 		info->reg_type = PTR_TO_SOCK_COMMON_OR_NULL;
 		break;