Messages in this thread Patch in this message | | | From | Paul Moore <> | Subject | Re: [PATCH 2/3] [RFC] seccomp: give BPF x32 bit when restoring x32 filter | Date | Fri, 11 Jul 2014 12:36:23 -0400 |
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On Thursday, July 10, 2014 11:38:13 PM Richard Guy Briggs wrote: > Commit > fca460f hpa@zytor.com 2012-02-19 07:56:26 -0800 > x32: Handle the x32 system call flag > > provided a method to multiplex architecture with the syscall number for X32 > calls. > > Commit > 8b4b9f2 pmoore@redhat.com 2013-02-15 12:21:43 -0500 > x86: remove the x32 syscall bitmask from syscall_get_nr() > > broke audit and potentially other users of syscall_get_nr() which depend on > that call as named.
Arguably audit is broken anyway by not correctly treating syscall numbers as 32 bit integers like everyone else.
The commit above, 8b4b9f2, changed syscall_get_nr() so that it returned the same syscall number that is used by the architecture's ABI; just like every* other architecture in the kernel.
* Admittedly I didn't check every architecture's implementation, but after a half dozen I stopped checking as there was a definite trend.
{snip}
> diff --git a/arch/x86/include/asm/syscall.h b/arch/x86/include/asm/syscall.h > index d6a756a..d58b6be 100644 > --- a/arch/x86/include/asm/syscall.h > +++ b/arch/x86/include/asm/syscall.h > @@ -236,6 +236,10 @@ static inline int syscall_get_arch(void) > return AUDIT_ARCH_I386; > #endif > /* Both x32 and x86_64 are considered "64-bit". */ > +#ifdef CONFIG_X86_X32_ABI > + if (task_pt_regs(current)->orig_ax & __X32_SYSCALL_BIT) > + return AUDIT_ARCH_X86_X32; > +#endif
No. See my comments above and in other parts of this thread.
> return AUDIT_ARCH_X86_64; > } > #endif /* CONFIG_X86_32 */ > diff --git a/kernel/seccomp.c b/kernel/seccomp.c > index b35c215..bc18214 100644 > --- a/kernel/seccomp.c > +++ b/kernel/seccomp.c > @@ -73,6 +73,12 @@ static void populate_seccomp_data(struct seccomp_data > *sd) > > sd->nr = syscall_get_nr(task, regs); > sd->arch = syscall_get_arch(); > +#ifdef CONFIG_X86_X32_ABI > + if (sd->arch == AUDIT_ARCH_X86_X32) { > + sd->arch = AUDIT_ARCH_X86_64; > + sd->nr |= __X32_SYSCALL_BIT; > + } > +#endif
Once again, I'm not really sure I need to comment further here, but don't change syscall_get_nr(), it should return the same syscall number as was used by userspace to initiate the syscall. If you really want to use the new AUDIT_ARCH_X86_X32 macro/define, go ahead, but make sure you rewrite it to the x86-64 value here so as to not break compatibility with existing seccomp filter users.
-- paul moore security and virtualization @ redhat
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