[tip: x86/urgent] x86/syscall: Include asm/ptrace.h in syscall_wrapper header

[tip-bot2 for Jiri Olsa]

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     9440c42941606af4c379afa3cf8624f0dc43a629
Gitweb:        https://git.kernel.org/tip/9440c42941606af4c379afa3cf8624f0dc43a629
Author:        Jiri Olsa <olsajiri@xxxxxxxxx>
AuthorDate:    Tue, 18 Oct 2022 14:27:08 +02:00
Committer:     Borislav Petkov <bp@xxxxxxx>
CommitterDate: Mon, 24 Oct 2022 17:57:28 +02:00

x86/syscall: Include asm/ptrace.h in syscall_wrapper header

With just the forward declaration of the 'struct pt_regs' in
syscall_wrapper.h, the syscall stub functions:

  __[x64|ia32]_sys_*(struct pt_regs *regs)

will have different definition of 'regs' argument in BTF data
based on which object file they are defined in.

If the syscall's object includes 'struct pt_regs' definition,
the BTF argument data will point to a 'struct pt_regs' record,
like:

  [226] STRUCT 'pt_regs' size=168 vlen=21
         'r15' type_id=1 bits_offset=0
         'r14' type_id=1 bits_offset=64
         'r13' type_id=1 bits_offset=128
  ...

If not, it will point to a fwd declaration record:

  [15439] FWD 'pt_regs' fwd_kind=struct

and make bpf tracing program hooking on those functions unable
to access fields from 'struct pt_regs'.

Include asm/ptrace.h directly in syscall_wrapper.h to make sure all
syscalls see 'struct pt_regs' definition. This then results in BTF for
'__*_sys_*(struct pt_regs *regs)' functions to point to the actual
struct, not just the forward declaration.

  [ bp: No Fixes tag as this is not really a bug fix but "adjustment" so
    that BTF is happy. ]

Reported-by: Akihiro HARAI <jharai0815@xxxxxxxxx>
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # this is needed only for BTF so kernels >= 5.15
Link: https://lore.kernel.org/r/20221018122708.823792-1-jolsa@xxxxxxxxxx
---
 arch/x86/include/asm/syscall_wrapper.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/syscall_wrapper.h b/arch/x86/include/asm/syscall_wrapper.h
index 59358d1..fd2669b 100644
--- a/arch/x86/include/asm/syscall_wrapper.h
+++ b/arch/x86/include/asm/syscall_wrapper.h
@@ -6,7 +6,7 @@
 #ifndef _ASM_X86_SYSCALL_WRAPPER_H
 #define _ASM_X86_SYSCALL_WRAPPER_H
 
-struct pt_regs;
+#include <asm/ptrace.h>
 
 extern long __x64_sys_ni_syscall(const struct pt_regs *regs);
 extern long __ia32_sys_ni_syscall(const struct pt_regs *regs);