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author | Sami Tolvanen <samitolvanen@google.com> | 2023-07-10 21:35:46 +0300 |
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committer | Palmer Dabbelt <palmer@rivosinc.com> | 2023-08-24 00:16:36 +0300 |
commit | 08d0ce30e0e4fcb5f06c90fe40387b1ce9324833 (patch) | |
tree | 69f769ebd80061215865aa13bc4bc301ab4e446f /arch/riscv/include/asm/syscall_wrapper.h | |
parent | 06c2afb862f9da8dc5efa4b6076a0e48c3fbaaa5 (diff) | |
download | linux-08d0ce30e0e4fcb5f06c90fe40387b1ce9324833.tar.xz |
riscv: Implement syscall wrappers
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>
Diffstat (limited to 'arch/riscv/include/asm/syscall_wrapper.h')
-rw-r--r-- | arch/riscv/include/asm/syscall_wrapper.h | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/arch/riscv/include/asm/syscall_wrapper.h b/arch/riscv/include/asm/syscall_wrapper.h new file mode 100644 index 000000000000..1d7942c8a6cb --- /dev/null +++ b/arch/riscv/include/asm/syscall_wrapper.h @@ -0,0 +1,87 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * syscall_wrapper.h - riscv specific wrappers to syscall definitions + * + * Based on arch/arm64/include/syscall_wrapper.h + */ + +#ifndef __ASM_SYSCALL_WRAPPER_H +#define __ASM_SYSCALL_WRAPPER_H + +#include <asm/ptrace.h> + +asmlinkage long __riscv_sys_ni_syscall(const struct pt_regs *); + +#define SC_RISCV_REGS_TO_ARGS(x, ...) \ + __MAP(x,__SC_ARGS \ + ,,regs->orig_a0,,regs->a1,,regs->a2 \ + ,,regs->a3,,regs->a4,,regs->a5,,regs->a6) + +#ifdef CONFIG_COMPAT + +#define COMPAT_SYSCALL_DEFINEx(x, name, ...) \ + asmlinkage long __riscv_compat_sys##name(const struct pt_regs *regs); \ + ALLOW_ERROR_INJECTION(__riscv_compat_sys##name, ERRNO); \ + static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \ + static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)); \ + asmlinkage long __riscv_compat_sys##name(const struct pt_regs *regs) \ + { \ + return __se_compat_sys##name(SC_RISCV_REGS_TO_ARGS(x,__VA_ARGS__)); \ + } \ + static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \ + { \ + return __do_compat_sys##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__)); \ + } \ + static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) + +#define COMPAT_SYSCALL_DEFINE0(sname) \ + asmlinkage long __riscv_compat_sys_##sname(const struct pt_regs *__unused); \ + ALLOW_ERROR_INJECTION(__riscv_compat_sys_##sname, ERRNO); \ + asmlinkage long __riscv_compat_sys_##sname(const struct pt_regs *__unused) + +#define COND_SYSCALL_COMPAT(name) \ + asmlinkage long __weak __riscv_compat_sys_##name(const struct pt_regs *regs); \ + asmlinkage long __weak __riscv_compat_sys_##name(const struct pt_regs *regs) \ + { \ + return sys_ni_syscall(); \ + } + +#define COMPAT_SYS_NI(name) \ + SYSCALL_ALIAS(__riscv_compat_sys_##name, sys_ni_posix_timers); + +#endif /* CONFIG_COMPAT */ + +#define __SYSCALL_DEFINEx(x, name, ...) \ + asmlinkage long __riscv_sys##name(const struct pt_regs *regs); \ + ALLOW_ERROR_INJECTION(__riscv_sys##name, ERRNO); \ + static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \ + static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)); \ + asmlinkage long __riscv_sys##name(const struct pt_regs *regs) \ + { \ + return __se_sys##name(SC_RISCV_REGS_TO_ARGS(x,__VA_ARGS__)); \ + } \ + static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \ + { \ + long ret = __do_sys##name(__MAP(x,__SC_CAST,__VA_ARGS__)); \ + __MAP(x,__SC_TEST,__VA_ARGS__); \ + __PROTECT(x, ret,__MAP(x,__SC_ARGS,__VA_ARGS__)); \ + return ret; \ + } \ + static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) + +#define SYSCALL_DEFINE0(sname) \ + SYSCALL_METADATA(_##sname, 0); \ + asmlinkage long __riscv_sys_##sname(const struct pt_regs *__unused); \ + ALLOW_ERROR_INJECTION(__riscv_sys_##sname, ERRNO); \ + asmlinkage long __riscv_sys_##sname(const struct pt_regs *__unused) + +#define COND_SYSCALL(name) \ + asmlinkage long __weak __riscv_sys_##name(const struct pt_regs *regs); \ + asmlinkage long __weak __riscv_sys_##name(const struct pt_regs *regs) \ + { \ + return sys_ni_syscall(); \ + } + +#define SYS_NI(name) SYSCALL_ALIAS(__riscv_sys_##name, sys_ni_posix_timers); + +#endif /* __ASM_SYSCALL_WRAPPER_H */ |