From a0727e8ce513fe6890416da960181ceb10fbfae6 Mon Sep 17 00:00:00 2001 From: Will Drewry Date: Thu, 12 Apr 2012 16:48:00 -0500 Subject: [PATCH] signal, x86: add SIGSYS info and make it synchronous. This change enables SIGSYS, defines _sigfields._sigsys, and adds x86 (compat) arch support. _sigsys defines fields which allow a signal handler to receive the triggering system call number, the relevant AUDIT_ARCH_* value for that number, and the address of the callsite. SIGSYS is added to the SYNCHRONOUS_MASK because it is desirable for it to have setup_frame() called for it. The goal is to ensure that ucontext_t reflects the machine state from the time-of-syscall and not from another signal handler. The first consumer of SIGSYS would be seccomp filter. In particular, a filter program could specify a new return value, SECCOMP_RET_TRAP, which would result in the system call being denied and the calling thread signaled. This also means that implementing arch-specific support can be dependent upon HAVE_ARCH_SECCOMP_FILTER. Suggested-by: H. Peter Anvin Signed-off-by: Will Drewry Acked-by: Serge Hallyn Reviewed-by: H. Peter Anvin Acked-by: Eric Paris v18: - added acked by, rebase v17: - rebase and reviewed-by addition v14: - rebase/nochanges v13: - rebase on to 88ebdda6159ffc15699f204c33feb3e431bf9bdc v12: - reworded changelog (oleg@redhat.com) v11: - fix dropped words in the change description - added fallback copy_siginfo support. - added __ARCH_SIGSYS define to allow stepped arch support. v10: - first version based on suggestion Signed-off-by: James Morris --- arch/x86/ia32/ia32_signal.c | 4 ++++ arch/x86/include/asm/ia32.h | 6 ++++++ include/asm-generic/siginfo.h | 22 ++++++++++++++++++++++ kernel/signal.c | 9 ++++++++- 4 files changed, 40 insertions(+), 1 deletion(-) diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c index a69245ba27e3..0b3f2354f6aa 100644 --- a/arch/x86/ia32/ia32_signal.c +++ b/arch/x86/ia32/ia32_signal.c @@ -67,6 +67,10 @@ int copy_siginfo_to_user32(compat_siginfo_t __user *to, siginfo_t *from) switch (from->si_code >> 16) { case __SI_FAULT >> 16: break; + case __SI_SYS >> 16: + put_user_ex(from->si_syscall, &to->si_syscall); + put_user_ex(from->si_arch, &to->si_arch); + break; case __SI_CHLD >> 16: if (ia32) { put_user_ex(from->si_utime, &to->si_utime); diff --git a/arch/x86/include/asm/ia32.h b/arch/x86/include/asm/ia32.h index ee52760549f0..b04cbdb138cd 100644 --- a/arch/x86/include/asm/ia32.h +++ b/arch/x86/include/asm/ia32.h @@ -144,6 +144,12 @@ typedef struct compat_siginfo { int _band; /* POLL_IN, POLL_OUT, POLL_MSG */ int _fd; } _sigpoll; + + struct { + unsigned int _call_addr; /* calling insn */ + int _syscall; /* triggering system call number */ + unsigned int _arch; /* AUDIT_ARCH_* of syscall */ + } _sigsys; } _sifields; } compat_siginfo_t; diff --git a/include/asm-generic/siginfo.h b/include/asm-generic/siginfo.h index 0dd4e87f6fba..31306f55eb02 100644 --- a/include/asm-generic/siginfo.h +++ b/include/asm-generic/siginfo.h @@ -90,9 +90,18 @@ typedef struct siginfo { __ARCH_SI_BAND_T _band; /* POLL_IN, POLL_OUT, POLL_MSG */ int _fd; } _sigpoll; + + /* SIGSYS */ + struct { + void __user *_call_addr; /* calling insn */ + int _syscall; /* triggering system call number */ + unsigned int _arch; /* AUDIT_ARCH_* of syscall */ + } _sigsys; } _sifields; } siginfo_t; +/* If the arch shares siginfo, then it has SIGSYS. */ +#define __ARCH_SIGSYS #endif /* @@ -116,6 +125,11 @@ typedef struct siginfo { #define si_addr_lsb _sifields._sigfault._addr_lsb #define si_band _sifields._sigpoll._band #define si_fd _sifields._sigpoll._fd +#ifdef __ARCH_SIGSYS +#define si_call_addr _sifields._sigsys._call_addr +#define si_syscall _sifields._sigsys._syscall +#define si_arch _sifields._sigsys._arch +#endif #ifdef __KERNEL__ #define __SI_MASK 0xffff0000u @@ -126,6 +140,7 @@ typedef struct siginfo { #define __SI_CHLD (4 << 16) #define __SI_RT (5 << 16) #define __SI_MESGQ (6 << 16) +#define __SI_SYS (7 << 16) #define __SI_CODE(T,N) ((T) | ((N) & 0xffff)) #else #define __SI_KILL 0 @@ -135,6 +150,7 @@ typedef struct siginfo { #define __SI_CHLD 0 #define __SI_RT 0 #define __SI_MESGQ 0 +#define __SI_SYS 0 #define __SI_CODE(T,N) (N) #endif @@ -231,6 +247,12 @@ typedef struct siginfo { #define POLL_HUP (__SI_POLL|6) /* device disconnected */ #define NSIGPOLL 6 +/* + * SIGSYS si_codes + */ +#define SYS_SECCOMP (__SI_SYS|1) /* seccomp triggered */ +#define NSIGSYS 1 + /* * sigevent definitions * diff --git a/kernel/signal.c b/kernel/signal.c index 17afcaf582d0..1a006b5d9d9d 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -160,7 +160,7 @@ void recalc_sigpending(void) #define SYNCHRONOUS_MASK \ (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \ - sigmask(SIGTRAP) | sigmask(SIGFPE)) + sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS)) int next_signal(struct sigpending *pending, sigset_t *mask) { @@ -2706,6 +2706,13 @@ int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from) err |= __put_user(from->si_uid, &to->si_uid); err |= __put_user(from->si_ptr, &to->si_ptr); break; +#ifdef __ARCH_SIGSYS + case __SI_SYS: + err |= __put_user(from->si_call_addr, &to->si_call_addr); + err |= __put_user(from->si_syscall, &to->si_syscall); + err |= __put_user(from->si_arch, &to->si_arch); + break; +#endif default: /* this is just in case for now ... */ err |= __put_user(from->si_pid, &to->si_pid); err |= __put_user(from->si_uid, &to->si_uid);