08d0ce30e0
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>
88 lines
3.2 KiB
C
88 lines
3.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* syscall_wrapper.h - riscv specific wrappers to syscall definitions
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*
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* Based on arch/arm64/include/syscall_wrapper.h
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*/
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#ifndef __ASM_SYSCALL_WRAPPER_H
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#define __ASM_SYSCALL_WRAPPER_H
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#include <asm/ptrace.h>
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asmlinkage long __riscv_sys_ni_syscall(const struct pt_regs *);
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#define SC_RISCV_REGS_TO_ARGS(x, ...) \
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__MAP(x,__SC_ARGS \
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,,regs->orig_a0,,regs->a1,,regs->a2 \
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,,regs->a3,,regs->a4,,regs->a5,,regs->a6)
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#ifdef CONFIG_COMPAT
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#define COMPAT_SYSCALL_DEFINEx(x, name, ...) \
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asmlinkage long __riscv_compat_sys##name(const struct pt_regs *regs); \
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ALLOW_ERROR_INJECTION(__riscv_compat_sys##name, ERRNO); \
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static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \
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static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)); \
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asmlinkage long __riscv_compat_sys##name(const struct pt_regs *regs) \
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{ \
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return __se_compat_sys##name(SC_RISCV_REGS_TO_ARGS(x,__VA_ARGS__)); \
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} \
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static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \
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{ \
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return __do_compat_sys##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__)); \
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} \
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static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
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#define COMPAT_SYSCALL_DEFINE0(sname) \
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asmlinkage long __riscv_compat_sys_##sname(const struct pt_regs *__unused); \
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ALLOW_ERROR_INJECTION(__riscv_compat_sys_##sname, ERRNO); \
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asmlinkage long __riscv_compat_sys_##sname(const struct pt_regs *__unused)
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#define COND_SYSCALL_COMPAT(name) \
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asmlinkage long __weak __riscv_compat_sys_##name(const struct pt_regs *regs); \
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asmlinkage long __weak __riscv_compat_sys_##name(const struct pt_regs *regs) \
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{ \
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return sys_ni_syscall(); \
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}
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#define COMPAT_SYS_NI(name) \
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SYSCALL_ALIAS(__riscv_compat_sys_##name, sys_ni_posix_timers);
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#endif /* CONFIG_COMPAT */
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#define __SYSCALL_DEFINEx(x, name, ...) \
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asmlinkage long __riscv_sys##name(const struct pt_regs *regs); \
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ALLOW_ERROR_INJECTION(__riscv_sys##name, ERRNO); \
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static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \
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static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)); \
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asmlinkage long __riscv_sys##name(const struct pt_regs *regs) \
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{ \
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return __se_sys##name(SC_RISCV_REGS_TO_ARGS(x,__VA_ARGS__)); \
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} \
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static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \
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{ \
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long ret = __do_sys##name(__MAP(x,__SC_CAST,__VA_ARGS__)); \
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__MAP(x,__SC_TEST,__VA_ARGS__); \
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__PROTECT(x, ret,__MAP(x,__SC_ARGS,__VA_ARGS__)); \
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return ret; \
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} \
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static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
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#define SYSCALL_DEFINE0(sname) \
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SYSCALL_METADATA(_##sname, 0); \
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asmlinkage long __riscv_sys_##sname(const struct pt_regs *__unused); \
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ALLOW_ERROR_INJECTION(__riscv_sys_##sname, ERRNO); \
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asmlinkage long __riscv_sys_##sname(const struct pt_regs *__unused)
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#define COND_SYSCALL(name) \
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asmlinkage long __weak __riscv_sys_##name(const struct pt_regs *regs); \
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asmlinkage long __weak __riscv_sys_##name(const struct pt_regs *regs) \
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{ \
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return sys_ni_syscall(); \
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}
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#define SYS_NI(name) SYSCALL_ALIAS(__riscv_sys_##name, sys_ni_posix_timers);
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#endif /* __ASM_SYSCALL_WRAPPER_H */
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