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Message-Id: <1330559620-23543-8-git-send-email-wad@chromium.org>
Date: Wed, 29 Feb 2012 17:53:35 -0600
From: Will Drewry <wad@...omium.org>
To: linux-kernel@...r.kernel.org
Cc: linux-arch@...r.kernel.org, linux-doc@...r.kernel.org,
kernel-hardening@...ts.openwall.com, netdev@...r.kernel.org,
x86@...nel.org, arnd@...db.de, davem@...emloft.net, hpa@...or.com,
mingo@...hat.com, oleg@...hat.com, peterz@...radead.org,
rdunlap@...otime.net, mcgrathr@...omium.org, tglx@...utronix.de,
luto@....edu, eparis@...hat.com, serge.hallyn@...onical.com,
djm@...drot.org, scarybeasts@...il.com, indan@....nu,
pmoore@...hat.com, akpm@...ux-foundation.org, corbet@....net,
eric.dumazet@...il.com, markus@...omium.org,
coreyb@...ux.vnet.ibm.com, keescook@...omium.org,
Will Drewry <wad@...omium.org>
Subject: [PATCH v12 08/13] 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.
v12: - reworded changelog (oleg@...hat.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
Suggested-by: H. Peter Anvin <hpa@...or.com>
Signed-off-by: Will Drewry <wad@...omium.org>
---
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 deletions(-)
diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index 942bfbe..7f71cb2 100644
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -66,6 +66,10 @@ 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:
put_user_ex(from->si_utime, &to->si_utime);
put_user_ex(from->si_stime, &to->si_stime);
diff --git a/arch/x86/include/asm/ia32.h b/arch/x86/include/asm/ia32.h
index c6435ab..bcc99e8 100644
--- a/arch/x86/include/asm/ia32.h
+++ b/arch/x86/include/asm/ia32.h
@@ -135,6 +135,12 @@ 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 0dd4e87..31306f5 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
@@ -232,6 +248,12 @@ typedef struct siginfo {
#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
diff --git a/kernel/signal.c b/kernel/signal.c
index 354b104..12b23ff 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)
{
@@ -2700,6 +2700,13 @@ 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);
--
1.7.5.4
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