diff options
| author | Dominik Brodowski <linux@dominikbrodowski.net> | 2018-04-05 11:53:04 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2018-04-05 16:59:38 +0200 |
| commit | ebeb8c82ffaf94435806ff0b686fffd41dd410b5 (patch) | |
| tree | 27e14910bb529a9e146949a9ea0563012bca2ea0 /arch/x86/entry/common.c | |
| parent | 7303e30ec1d8fb5ca1f07c92d069241c32b2ee1b (diff) | |
syscalls/x86: Use 'struct pt_regs' based syscall calling for IA32_EMULATION and x32
Extend ARCH_HAS_SYSCALL_WRAPPER for i386 emulation and for x32 on 64-bit
x86.
For x32, all we need to do is to create an additional stub for each
compat syscall which decodes the parameters in x86-64 ordering, e.g.:
asmlinkage long __compat_sys_x32_xyzzy(struct pt_regs *regs)
{
return c_SyS_xyzzy(regs->di, regs->si, regs->dx);
}
For i386 emulation, we need to teach compat_sys_*() to take struct
pt_regs as its only argument, e.g.:
asmlinkage long __compat_sys_ia32_xyzzy(struct pt_regs *regs)
{
return c_SyS_xyzzy(regs->bx, regs->cx, regs->dx);
}
In addition, we need to create additional stubs for common syscalls
(that is, for syscalls which have the same parameters on 32-bit and
64-bit), e.g.:
asmlinkage long __sys_ia32_xyzzy(struct pt_regs *regs)
{
return c_sys_xyzzy(regs->bx, regs->cx, regs->dx);
}
This approach avoids leaking random user-provided register content down
the call chain.
This patch is based on an original proof-of-concept
| From: Linus Torvalds <torvalds@linux-foundation.org>
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
and was split up and heavily modified by me, in particular to base it on
ARCH_HAS_SYSCALL_WRAPPER.
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180405095307.3730-6-linux@dominikbrodowski.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/entry/common.c')
| -rw-r--r-- | arch/x86/entry/common.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index e1b91bffa988..425f798b39e3 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -325,6 +325,9 @@ static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs) if (likely(nr < IA32_NR_syscalls)) { nr = array_index_nospec(nr, IA32_NR_syscalls); +#ifdef CONFIG_SYSCALL_PTREGS + regs->ax = ia32_sys_call_table[nr](regs); +#else /* * It's possible that a 32-bit syscall implementation * takes a 64-bit parameter but nonetheless assumes that @@ -335,6 +338,7 @@ static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs) (unsigned int)regs->bx, (unsigned int)regs->cx, (unsigned int)regs->dx, (unsigned int)regs->si, (unsigned int)regs->di, (unsigned int)regs->bp); +#endif /* CONFIG_SYSCALL_PTREGS */ } syscall_return_slowpath(regs); |