Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit a0727e8c authored by Will Drewry's avatar Will Drewry Committed by James Morris
Browse files

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: default avatarH. Peter Anvin <hpa@zytor.com>
Signed-off-by: default avatarWill Drewry <wad@chromium.org>
Acked-by: default avatarSerge Hallyn <serge.hallyn@canonical.com>
Reviewed-by: default avatarH. Peter Anvin <hpa@zytor.com>
Acked-by: default avatarEric Paris <eparis@redhat.com>

v18: - added acked by, rebase
v17: - rebase and reviewed-by addition
v14: - rebase/nochanges
v13: - rebase on to 88ebdda6
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: default avatarJames Morris <james.l.morris@oracle.com>
parent acf3b2c7

arch/x86/ia32/ia32_signal.c

+4 −0
Original line number Diff line number Diff line
@@ -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);

arch/x86/include/asm/ia32.h

+6 −0
Original line number Diff line number Diff line
@@ -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;

include/asm-generic/siginfo.h

+22 −0
Original line number Diff line number Diff line
@@ -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

 *

kernel/signal.c

+8 −1
Original line number Diff line number Diff line
@@ -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);