| Message ID | 20200904203147.2908430-3-krisman@collabora.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Syscall User Dispatch | expand |
On Fri, Sep 04, 2020 at 04:31:40PM -0400, Gabriel Krisman Bertazi wrote: > Syscalls that use common entry code (x86 at the moment of this writing) > need to have their defines updated inside this commit. This added a > measureable overhead of 1ns to seccomp_benchmark selftests on a > bare-metal AMD system. > > Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com> > --- > arch/x86/include/asm/thread_info.h | 4 ++-- > include/linux/entry-common.h | 6 +----- > kernel/entry/common.c | 24 +++++++++++++++++++++--- > 3 files changed, 24 insertions(+), 10 deletions(-) > > diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h > index 267701ae3d86..cf723181e1f2 100644 > --- a/arch/x86/include/asm/thread_info.h > +++ b/arch/x86/include/asm/thread_info.h > @@ -82,7 +82,7 @@ struct thread_info { > #define TIF_SSBD 5 /* Speculative store bypass disable */ > #define TIF_SYSCALL_EMU 6 /* syscall emulation active */ > #define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */ > -#define TIF_SECCOMP 8 /* secure computing */ > +#define TIF_SYSCALL_INTERCEPT 8 /* Intercept system call */ > #define TIF_SPEC_IB 9 /* Indirect branch speculation mitigation */ > #define TIF_SPEC_FORCE_UPDATE 10 /* Force speculation MSR update in context switch */ > #define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */ > @@ -112,7 +112,7 @@ struct thread_info { > #define _TIF_SSBD (1 << TIF_SSBD) > #define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU) > #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) > -#define _TIF_SECCOMP (1 << TIF_SECCOMP) > +#define _TIF_SYSCALL_INTERCEPT (1 << TIF_SYSCALL_INTERCEPT) > #define _TIF_SPEC_IB (1 << TIF_SPEC_IB) > #define _TIF_SPEC_FORCE_UPDATE (1 << TIF_SPEC_FORCE_UPDATE) > #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY) > diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h > index efebbffcd5cc..72ce9ca860c6 100644 > --- a/include/linux/entry-common.h > +++ b/include/linux/entry-common.h > @@ -21,10 +21,6 @@ > # define _TIF_SYSCALL_TRACEPOINT (0) > #endif > > -#ifndef _TIF_SECCOMP > -# define _TIF_SECCOMP (0) > -#endif > - > #ifndef _TIF_SYSCALL_AUDIT > # define _TIF_SYSCALL_AUDIT (0) > #endif > @@ -45,7 +41,7 @@ > #endif > > #define SYSCALL_ENTER_WORK \ > - (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SECCOMP | \ > + (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SYSCALL_INTERCEPT | \ > _TIF_SYSCALL_TRACEPOINT | _TIF_SYSCALL_EMU | \ > ARCH_SYSCALL_ENTER_WORK) > > diff --git a/kernel/entry/common.c b/kernel/entry/common.c > index fcae019158ca..44fd089d59da 100644 > --- a/kernel/entry/common.c > +++ b/kernel/entry/common.c > @@ -4,6 +4,7 @@ > #include <linux/entry-common.h> > #include <linux/livepatch.h> > #include <linux/audit.h> > +#include <linux/syscall_intercept.h> > > #define CREATE_TRACE_POINTS > #include <trace/events/syscalls.h> > @@ -41,6 +42,20 @@ static inline void syscall_enter_audit(struct pt_regs *regs, long syscall) > } > } > > +static inline long do_syscall_intercept(struct pt_regs *regs) Hey Gabriel, I think you can drop the pt_regs argument and just have this be static inline do_syscall_intercept(void) otherwise Acked-by: Christian Brauner <christian.brauner@ubuntu.com> > +{ > + int sysint_work = READ_ONCE(current->syscall_intercept); > + int ret; > + > + if (sysint_work & SYSINT_SECCOMP) { > + ret = __secure_computing(NULL); > + if (ret == -1L) > + return ret; > + } > + > + return 0; > +} > + > static long syscall_trace_enter(struct pt_regs *regs, long syscall, > unsigned long ti_work) > { > @@ -53,9 +68,12 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall, > return -1L; > } > > - /* Do seccomp after ptrace, to catch any tracer changes. */ > - if (ti_work & _TIF_SECCOMP) { > - ret = __secure_computing(NULL); > + /* > + * Do syscall interception like seccomp after ptrace, to catch > + * any tracer changes. > + */ > + if (ti_work & _TIF_SYSCALL_INTERCEPT) { > + ret = do_syscall_intercept(regs); > if (ret == -1L) > return ret; > } > -- > 2.28.0
On Fri, Sep 04, 2020 at 04:31:40PM -0400, Gabriel Krisman Bertazi wrote: > diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h > index efebbffcd5cc..72ce9ca860c6 100644 > --- a/include/linux/entry-common.h > +++ b/include/linux/entry-common.h > @@ -21,10 +21,6 @@ > # define _TIF_SYSCALL_TRACEPOINT (0) > #endif > > -#ifndef _TIF_SECCOMP > -# define _TIF_SECCOMP (0) > -#endif > - > #ifndef _TIF_SYSCALL_AUDIT > # define _TIF_SYSCALL_AUDIT (0) > #endif Why doesn't this add: #ifndef _TIF_SYSCALL_INTERCEPT #define _TIF_SYSCALL_INTERCEPT (0) #endif ?
peterz@infradead.org writes: > On Fri, Sep 04, 2020 at 04:31:40PM -0400, Gabriel Krisman Bertazi wrote: >> diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h >> index efebbffcd5cc..72ce9ca860c6 100644 >> --- a/include/linux/entry-common.h >> +++ b/include/linux/entry-common.h >> @@ -21,10 +21,6 @@ >> # define _TIF_SYSCALL_TRACEPOINT (0) >> #endif >> >> -#ifndef _TIF_SECCOMP >> -# define _TIF_SECCOMP (0) >> -#endif >> - >> #ifndef _TIF_SYSCALL_AUDIT >> # define _TIF_SYSCALL_AUDIT (0) >> #endif > > Why doesn't this add: > > #ifndef _TIF_SYSCALL_INTERCEPT > #define _TIF_SYSCALL_INTERCEPT (0) > #endif > I will add in the next version. Thanks!
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index 267701ae3d86..cf723181e1f2 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -82,7 +82,7 @@ struct thread_info { #define TIF_SSBD 5 /* Speculative store bypass disable */ #define TIF_SYSCALL_EMU 6 /* syscall emulation active */ #define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */ -#define TIF_SECCOMP 8 /* secure computing */ +#define TIF_SYSCALL_INTERCEPT 8 /* Intercept system call */ #define TIF_SPEC_IB 9 /* Indirect branch speculation mitigation */ #define TIF_SPEC_FORCE_UPDATE 10 /* Force speculation MSR update in context switch */ #define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */ @@ -112,7 +112,7 @@ struct thread_info { #define _TIF_SSBD (1 << TIF_SSBD) #define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU) #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) -#define _TIF_SECCOMP (1 << TIF_SECCOMP) +#define _TIF_SYSCALL_INTERCEPT (1 << TIF_SYSCALL_INTERCEPT) #define _TIF_SPEC_IB (1 << TIF_SPEC_IB) #define _TIF_SPEC_FORCE_UPDATE (1 << TIF_SPEC_FORCE_UPDATE) #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY) diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h index efebbffcd5cc..72ce9ca860c6 100644 --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -21,10 +21,6 @@ # define _TIF_SYSCALL_TRACEPOINT (0) #endif -#ifndef _TIF_SECCOMP -# define _TIF_SECCOMP (0) -#endif - #ifndef _TIF_SYSCALL_AUDIT # define _TIF_SYSCALL_AUDIT (0) #endif @@ -45,7 +41,7 @@ #endif #define SYSCALL_ENTER_WORK \ - (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SECCOMP | \ + (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SYSCALL_INTERCEPT | \ _TIF_SYSCALL_TRACEPOINT | _TIF_SYSCALL_EMU | \ ARCH_SYSCALL_ENTER_WORK) diff --git a/kernel/entry/common.c b/kernel/entry/common.c index fcae019158ca..44fd089d59da 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -4,6 +4,7 @@ #include <linux/entry-common.h> #include <linux/livepatch.h> #include <linux/audit.h> +#include <linux/syscall_intercept.h> #define CREATE_TRACE_POINTS #include <trace/events/syscalls.h> @@ -41,6 +42,20 @@ static inline void syscall_enter_audit(struct pt_regs *regs, long syscall) } } +static inline long do_syscall_intercept(struct pt_regs *regs) +{ + int sysint_work = READ_ONCE(current->syscall_intercept); + int ret; + + if (sysint_work & SYSINT_SECCOMP) { + ret = __secure_computing(NULL); + if (ret == -1L) + return ret; + } + + return 0; +} + static long syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long ti_work) { @@ -53,9 +68,12 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall, return -1L; } - /* Do seccomp after ptrace, to catch any tracer changes. */ - if (ti_work & _TIF_SECCOMP) { - ret = __secure_computing(NULL); + /* + * Do syscall interception like seccomp after ptrace, to catch + * any tracer changes. + */ + if (ti_work & _TIF_SYSCALL_INTERCEPT) { + ret = do_syscall_intercept(regs); if (ret == -1L) return ret; }
Syscalls that use common entry code (x86 at the moment of this writing) need to have their defines updated inside this commit. This added a measureable overhead of 1ns to seccomp_benchmark selftests on a bare-metal AMD system. Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com> --- arch/x86/include/asm/thread_info.h | 4 ++-- include/linux/entry-common.h | 6 +----- kernel/entry/common.c | 24 +++++++++++++++++++++--- 3 files changed, 24 insertions(+), 10 deletions(-)