linux.git/arch/riscv/kernel/compat_syscall_table.c, branch v6.9 Linux kernel source tree riscv: Implement syscall wrappers 2023-08-23T21:16:36+00:00 Sami Tolvanen samitolvanen@google.com 2023-07-10T18:35:46+00:00 08d0ce30e0e4fcb5f06c90fe40387b1ce9324833 Commit f0bddf50586d ("riscv: entry: Convert to generic entry") moved syscall handling to C code, which exposed function pointer type mismatches that trip fine-grained forward-edge Control-Flow Integrity (CFI) checks as syscall handlers are all called through the same syscall_t pointer type. To fix the type mismatches, implement pt_regs based syscall wrappers similarly to x86 and arm64. This patch is based on arm64 syscall wrappers added in commit 4378a7d4be30 ("arm64: implement syscall wrappers"), where the main goal was to minimize the risk of userspace-controlled values being used under speculation. This may be a concern for riscv in future as well. Following other architectures, the syscall wrappers generate three functions for each syscall; __riscv_<compat_>sys_<name> takes a pt_regs pointer and extracts arguments from registers, __se_<compat_>sys_<name> is a sign-extension wrapper that casts the long arguments to the correct types for the real syscall implementation, which is named __do_<compat_>sys_<name>. Reviewed-by: Kees Cook <keescook@chromium.org> Tested-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Link: https://lore.kernel.org/r/20230710183544.999540-9-samitolvanen@google.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> 
Commit f0bddf50586d ("riscv: entry: Convert to generic entry") moved
syscall handling to C code, which exposed function pointer type
mismatches that trip fine-grained forward-edge Control-Flow Integrity
(CFI) checks as syscall handlers are all called through the same
syscall_t pointer type. To fix the type mismatches, implement pt_regs
based syscall wrappers similarly to x86 and arm64.

This patch is based on arm64 syscall wrappers added in commit
4378a7d4be30 ("arm64: implement syscall wrappers"), where the main goal
was to minimize the risk of userspace-controlled values being used
under speculation. This may be a concern for riscv in future as well.

Following other architectures, the syscall wrappers generate three
functions for each syscall; __riscv_<compat_>sys_<name> takes a pt_regs
pointer and extracts arguments from registers, __se_<compat_>sys_<name>
is a sign-extension wrapper that casts the long arguments to the
correct types for the real syscall implementation, which is named
__do_<compat_>sys_<name>.

Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://lore.kernel.org/r/20230710183544.999540-9-samitolvanen@google.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
riscv: compat: syscall: Add compat_sys_call_table implementation 2022-04-26T20:36:25+00:00 Guo Ren guoren@linux.alibaba.com 2022-04-05T07:13:05+00:00 59c10c52f573faca862cda5ebcdd43831608eb5a Implement compat sys_call_table and some system call functions: truncate64, ftruncate64, fallocate, pread64, pwrite64, sync_file_range, readahead, fadvise64_64 which need argument translation. Signed-off-by: Guo Ren <guoren@linux.alibaba.com> Signed-off-by: Guo Ren <guoren@kernel.org> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Tested-by: Heiko Stuebner <heiko@sntech.de> Link: https://lore.kernel.org/r/20220405071314.3225832-12-guoren@kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> 
Implement compat sys_call_table and some system call functions:
truncate64, ftruncate64, fallocate, pread64, pwrite64,
sync_file_range, readahead, fadvise64_64 which need argument
translation.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20220405071314.3225832-12-guoren@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>