kernel/arch/x86/include/asm/syscall.h, branch linux-rolling-stable

syscall.h: introduce syscall_set_nr()

2025-05-12T00:48:15Z

Similar to syscall_set_arguments() that complements syscall_get_arguments(), introduce syscall_set_nr() that complements syscall_get_nr(). syscall_set_nr() is going to be needed along with syscall_set_arguments() on all HAVE_ARCH_TRACEHOOK architectures to implement PTRACE_SET_SYSCALL_INFO API. Link: https://lkml.kernel.org/r/20250303112020.GD24170@strace.io Signed-off-by: Dmitry V. Levin Tested-by: Charlie Jenkins Reviewed-by: Charlie Jenkins Acked-by: Helge Deller # parisc Reviewed-by: Maciej W. Rozycki # mips Cc: Alexander Gordeev Cc: Alexey Gladkov (Intel) Cc: Andreas Larsson Cc: anton ivanov Cc: Arnd Bergmann Cc: Borislav Betkov Cc: Brian Cain Cc: Christian Borntraeger Cc: Christian Zankel Cc: Christophe Leroy Cc: Dave Hansen Cc: Davide Berardi Cc: David S. Miller Cc: Dinh Nguyen Cc: Eugene Syromiatnikov Cc: Eugene Syromyatnikov Cc: Geert Uytterhoeven Cc: Guo Ren Cc: Heiko Carstens Cc: "H. Peter Anvin" Cc: Huacai Chen Cc: Ingo Molnar Cc: Johannes Berg Cc: John Paul Adrian Glaubitz Cc: Jonas Bonn Cc: Madhavan Srinivasan Cc: Max Filippov Cc: Michael Ellerman Cc: Michal Simek Cc: Mike Frysinger Cc: Naveen N Rao Cc: Nicholas Piggin Cc: Oleg Nesterov Cc: Renzo Davoi Cc: Richard Weinberger Cc: Rich Felker Cc: Russel King Cc: Shuah Khan Cc: Stafford Horne Cc: Stefan Kristiansson Cc: Sven Schnelle Cc: Thomas Gleinxer Cc: Vasily Gorbik Cc: Vineet Gupta Cc: WANG Xuerui Cc: Will Deacon Cc: Yoshinori Sato Signed-off-by: Andrew Morton

syscall.h: add syscall_set_arguments()

2025-05-12T00:48:15Z

This function is going to be needed on all HAVE_ARCH_TRACEHOOK architectures to implement PTRACE_SET_SYSCALL_INFO API. This partially reverts commit 7962c2eddbfe ("arch: remove unused function syscall_set_arguments()") by reusing some of old syscall_set_arguments() implementations. [nathan@kernel.org: fix compile time fortify checks] Link: https://lkml.kernel.org/r/20250408213131.GA2872426@ax162 Link: https://lkml.kernel.org/r/20250303112009.GC24170@strace.io Signed-off-by: Dmitry V. Levin Signed-off-by: Nathan Chancellor Tested-by: Charlie Jenkins Reviewed-by: Charlie Jenkins Acked-by: Helge Deller # parisc Reviewed-by: Maciej W. Rozycki [mips] Cc: Alexander Gordeev Cc: Alexey Gladkov (Intel) Cc: Andreas Larsson Cc: anton ivanov Cc: Arnd Bergmann Cc: Borislav Betkov Cc: Brian Cain Cc: Christian Borntraeger Cc: Christian Zankel Cc: Christophe Leroy Cc: Dave Hansen Cc: Davide Berardi Cc: David S. Miller Cc: Dinh Nguyen Cc: Eugene Syromiatnikov Cc: Eugene Syromyatnikov Cc: Geert Uytterhoeven Cc: Guo Ren Cc: Heiko Carstens Cc: "H. Peter Anvin" Cc: Huacai Chen Cc: Ingo Molnar Cc: Johannes Berg Cc: John Paul Adrian Glaubitz Cc: Jonas Bonn Cc: Madhavan Srinivasan Cc: Max Filippov Cc: Michael Ellerman Cc: Michal Simek Cc: Mike Frysinger Cc: Naveen N Rao Cc: Nicholas Piggin Cc: Oleg Nesterov Cc: Renzo Davoi Cc: Richard Weinberger Cc: Rich Felker Cc: Russel King Cc: Shuah Khan Cc: Stafford Horne Cc: Stefan Kristiansson Cc: Sven Schnelle Cc: Thomas Gleinxer Cc: Vasily Gorbik Cc: Vineet Gupta Cc: WANG Xuerui Cc: Will Deacon Cc: Yoshinori Sato Signed-off-by: Andrew Morton

x86/syscall: Avoid memcpy() for ia32 syscall_get_arguments()

2024-08-23T18:46:51Z

Modern (fortified) memcpy() prefers to avoid writing (or reading) beyond the end of the addressed destination (or source) struct member: In function ‘fortify_memcpy_chk’, inlined from ‘syscall_get_arguments’ at ./arch/x86/include/asm/syscall.h:85:2, inlined from ‘populate_seccomp_data’ at kernel/seccomp.c:258:2, inlined from ‘__seccomp_filter’ at kernel/seccomp.c:1231:3: ./include/linux/fortify-string.h:580:25: error: call to ‘__read_overflow2_field’ declared with attribute warning: detected read beyond size of field (2nd parameter); maybe use struct_group()? [-Werror=attribute-warning] 580 | __read_overflow2_field(q_size_field, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ As already done for x86_64 and compat mode, do not use memcpy() to extract syscall arguments from struct pt_regs but rather just perform direct assignments. Binary output differences are negligible, and actually ends up using less stack space: - sub $0x84,%esp + sub $0x6c,%esp and less text size: text data bss dec hex filename 10794 252 0 11046 2b26 gcc-32b/kernel/seccomp.o.stock 10714 252 0 10966 2ad6 gcc-32b/kernel/seccomp.o.after Closes: https://lore.kernel.org/lkml/9b69fb14-df89-4677-9c82-056ea9e706f5@gmail.com/ Reported-by: Mirsad Todorovac Signed-off-by: Kees Cook Signed-off-by: Dave Hansen Reviewed-by: Gustavo A. R. Silva Acked-by: Dave Hansen Tested-by: Mirsad Todorovac Link: https://lore.kernel.org/all/20240708202202.work.477-kees%40kernel.org

x86/bhi: Add support for clearing branch history at syscall entry

2024-04-08T17:27:05Z

Branch History Injection (BHI) attacks may allow a malicious application to influence indirect branch prediction in kernel by poisoning the branch history. eIBRS isolates indirect branch targets in ring0. The BHB can still influence the choice of indirect branch predictor entry, and although branch predictor entries are isolated between modes when eIBRS is enabled, the BHB itself is not isolated between modes. Alder Lake and new processors supports a hardware control BHI_DIS_S to mitigate BHI. For older processors Intel has released a software sequence to clear the branch history on parts that don't support BHI_DIS_S. Add support to execute the software sequence at syscall entry and VMexit to overwrite the branch history. For now, branch history is not cleared at interrupt entry, as malicious applications are not believed to have sufficient control over the registers, since previous register state is cleared at interrupt entry. Researchers continue to poke at this area and it may become necessary to clear at interrupt entry as well in the future. This mitigation is only defined here. It is enabled later. Signed-off-by: Pawan Gupta Co-developed-by: Daniel Sneddon Signed-off-by: Daniel Sneddon Signed-off-by: Thomas Gleixner Reviewed-by: Alexandre Chartre Reviewed-by: Josh Poimboeuf

x86/syscall: Don't force use of indirect calls for system calls

2024-04-08T17:27:05Z

Make build a switch statement instead, and the compiler can either decide to generate an indirect jump, or - more likely these days due to mitigations - just a series of conditional branches. Yes, the conditional branches also have branch prediction, but the branch prediction is much more controlled, in that it just causes speculatively running the wrong system call (harmless), rather than speculatively running possibly wrong random less controlled code gadgets. This doesn't mitigate other indirect calls, but the system call indirection is the first and most easily triggered case. Signed-off-by: Linus Torvalds Signed-off-by: Daniel Sneddon Signed-off-by: Thomas Gleixner Reviewed-by: Josh Poimboeuf

x86/entry/64: Convert SYSRET validation tests to C

2023-10-13T11:05:28Z

No change in functionality expected. Signed-off-by: Brian Gerst Signed-off-by: Ingo Molnar Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Josh Poimboeuf Cc: Uros Bizjak Link: https://lore.kernel.org/r/20231011224351.130935-2-brgerst@gmail.com

x86/entry/32: Convert do_fast_syscall_32() to bool return type

2023-10-05T08:06:42Z

Doesn't have to be 'long' - this simplifies the code a bit. Signed-off-by: Brian Gerst Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20230721161018.50214-5-brgerst@gmail.com

x86/entry: Add do_SYSENTER_32() prototype

2023-05-18T18:56:18Z

The 32-bit system call entry points can be called on both 32-bit and 64-bit kernels, but on the former the declarations are hidden: arch/x86/entry/common.c:238:24: error: no previous prototype for 'do_SYSENTER_32' [-Werror=missing-prototypes] Move them all out of the #ifdef block to avoid the warnings. Signed-off-by: Arnd Bergmann Signed-off-by: Dave Hansen Reviewed-by: Alexander Lobakin Link: https://lore.kernel.org/all/20230516193549.544673-12-arnd%40kernel.org

arch: remove unused function syscall_set_arguments()

2021-09-14T14:06:20Z

This function appears to have been unused since it was first introduced in commit 828c365cc8b8 ("tracehook: asm/syscall.h"). Signed-off-by: Peter Collingbourne Link: https://linux-review.googlesource.com/id/I8ce04f002903a37c0b6c1d16e9b2a3afa716c097 Signed-off-by: Arnd Bergmann

x86/entry: Use int everywhere for system call numbers

2021-05-25T08:07:00Z

System call numbers are defined as int, so use int everywhere for system call numbers. This is strictly a cleanup; it should not change anything user visible; all ABI changes have been done in the preceeding patches. [ tglx: Replaced the unsigned long cast ] Signed-off-by: H. Peter Anvin (Intel) Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20210518191303.4135296-7-hpa@zytor.com