diff options
| author |   Ingo Molnar <mingo@kernel.org> | 2015-03-29 11:02:34 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-03-31 11:45:19 +0200 |
| commit | 55474c48b4726fd3914c1ec47fced0f931729979 (patch) | |
| tree | cf2905156f4adad351dbd3195179deb939e24c73 /arch/x86/include/asm | |
| parent | x86/asm/entry/64: Do not GET_THREAD_INFO() too early (diff) | |
| download | linux-dev-55474c48b4726fd3914c1ec47fced0f931729979.tar.xz linux-dev-55474c48b4726fd3914c1ec47fced0f931729979.zip | |
x86/asm/entry: Remove user_mode_ignore_vm86()
user_mode_ignore_vm86() can be used instead of user_mode(), in
places where we have already done a v8086_mode() security
check of ptregs.
But doing this check in the wrong place would be a bug that
could result in security problems, and also the naming still
isn't very clear.
Furthermore, it only affects 32-bit kernels, while most
development happens on 64-bit kernels.
If we replace them with user_mode() checks then the cost is only
a very minor increase in various slowpaths:
text data bss dec hex filename
10573391 703562 1753042 13029995 c6d26b vmlinux.o.before
10573423 703562 1753042 13030027 c6d28b vmlinux.o.after
So lets get rid of this distinction once and for all.
Acked-by: Borislav Petkov <bp@suse.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brad Spengler <spender@grsecurity.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150329090233.GA1963@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm')
| -rw-r--r-- | arch/x86/include/asm/ptrace.h | 17 |
1 files changed, 0 insertions, 17 deletions
diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h index d20bae298852..19507ffa5d28 100644 --- a/arch/x86/include/asm/ptrace.h +++ b/arch/x86/include/asm/ptrace.h @@ -113,23 +113,6 @@ static inline int user_mode(struct pt_regs *regs) #endif } -/* - * This is the fastest way to check whether regs come from user space. - * It is unsafe if regs might come from vm86 mode, though -- in vm86 - * mode, all bits of CS and SS are completely under the user's control. - * The CPU considers vm86 mode to be CPL 3 regardless of CS and SS. - * - * Do NOT use this function unless you have already ruled out the - * possibility that regs came from vm86 mode. - * - * We check for RPL != 0 instead of RPL == 3 because we don't use rings - * 1 or 2 and this is more efficient. - */ -static inline int user_mode_ignore_vm86(struct pt_regs *regs) -{ - return (regs->cs & SEGMENT_RPL_MASK) != 0; -} - static inline int v8086_mode(struct pt_regs *regs) { #ifdef CONFIG_X86_32 |