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 <hpa@zytor.com>
Signed-off-by: Will Drewry <wad@chromium.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Reviewed-by: H. Peter Anvin <hpa@zytor.com>
Acked-by: Eric Paris <eparis@redhat.com>
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 <james.l.morris@oracle.com>
diff --git a/include/asm-generic/siginfo.h b/include/asm-generic/siginfo.h
index 0dd4e87..31306f5 100644
--- a/include/asm-generic/siginfo.h
+++ b/include/asm-generic/siginfo.h
@@ -90,9 +90,18 @@
__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 @@
#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 @@
#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 @@
#define __SI_CHLD 0
#define __SI_RT 0
#define __SI_MESGQ 0
+#define __SI_SYS 0
#define __SI_CODE(T,N) (N)
#endif
@@ -232,6 +248,12 @@
#define NSIGPOLL 6
/*
+ * SIGSYS si_codes
+ */
+#define SYS_SECCOMP (__SI_SYS|1) /* seccomp triggered */
+#define NSIGSYS 1
+
+/*
* sigevent definitions
*
* It seems likely that SIGEV_THREAD will have to be handled from