linux-brain/include/uapi/asm-generic/siginfo.h
Eric W. Biederman cc731525f2 signal: Remove kernel interal si_code magic
struct siginfo is a union and the kernel since 2.4 has been hiding a union
tag in the high 16bits of si_code using the values:
__SI_KILL
__SI_TIMER
__SI_POLL
__SI_FAULT
__SI_CHLD
__SI_RT
__SI_MESGQ
__SI_SYS

While this looks plausible on the surface, in practice this situation has
not worked well.

- Injected positive signals are not copied to user space properly
  unless they have these magic high bits set.

- Injected positive signals are not reported properly by signalfd
  unless they have these magic high bits set.

- These kernel internal values leaked to userspace via ptrace_peek_siginfo

- It was possible to inject these kernel internal values and cause the
  the kernel to misbehave.

- Kernel developers got confused and expected these kernel internal values
  in userspace in kernel self tests.

- Kernel developers got confused and set si_code to __SI_FAULT which
  is SI_USER in userspace which causes userspace to think an ordinary user
  sent the signal and that it was not kernel generated.

- The values make it impossible to reorganize the code to transform
  siginfo_copy_to_user into a plain copy_to_user.  As si_code must
  be massaged before being passed to userspace.

So remove these kernel internal si codes and make the kernel code simpler
and more maintainable.

To replace these kernel internal magic si_codes introduce the helper
function siginfo_layout, that takes a signal number and an si_code and
computes which union member of siginfo is being used.  Have
siginfo_layout return an enumeration so that gcc will have enough
information to warn if a switch statement does not handle all of union
members.

A couple of architectures have a messed up ABI that defines signal
specific duplications of SI_USER which causes more special cases in
siginfo_layout than I would like.  The good news is only problem
architectures pay the cost.

Update all of the code that used the previous magic __SI_ values to
use the new SIL_ values and to call siginfo_layout to get those
values.  Escept where not all of the cases are handled remove the
defaults in the switch statements so that if a new case is missed in
the future the lack will show up at compile time.

Modify the code that copies siginfo si_code to userspace to just copy
the value and not cast si_code to a short first.  The high bits are no
longer used to hold a magic union member.

Fixup the siginfo header files to stop including the __SI_ values in
their constants and for the headers that were missing it to properly
update the number of si_codes for each signal type.

The fixes to copy_siginfo_from_user32 implementations has the
interesting property that several of them perviously should never have
worked as the __SI_ values they depended up where kernel internal.
With that dependency gone those implementations should work much
better.

The idea of not passing the __SI_ values out to userspace and then
not reinserting them has been tested with criu and criu worked without
changes.

Ref: 2.4.0-test1
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-07-24 14:30:28 -05:00

301 lines
8.4 KiB
C

#ifndef _UAPI_ASM_GENERIC_SIGINFO_H
#define _UAPI_ASM_GENERIC_SIGINFO_H
#include <linux/compiler.h>
#include <linux/types.h>
typedef union sigval {
int sival_int;
void __user *sival_ptr;
} sigval_t;
/*
* This is the size (including padding) of the part of the
* struct siginfo that is before the union.
*/
#ifndef __ARCH_SI_PREAMBLE_SIZE
#define __ARCH_SI_PREAMBLE_SIZE (3 * sizeof(int))
#endif
#define SI_MAX_SIZE 128
#ifndef SI_PAD_SIZE
#define SI_PAD_SIZE ((SI_MAX_SIZE - __ARCH_SI_PREAMBLE_SIZE) / sizeof(int))
#endif
#ifndef __ARCH_SI_UID_T
#define __ARCH_SI_UID_T __kernel_uid32_t
#endif
/*
* The default "si_band" type is "long", as specified by POSIX.
* However, some architectures want to override this to "int"
* for historical compatibility reasons, so we allow that.
*/
#ifndef __ARCH_SI_BAND_T
#define __ARCH_SI_BAND_T long
#endif
#ifndef __ARCH_SI_CLOCK_T
#define __ARCH_SI_CLOCK_T __kernel_clock_t
#endif
#ifndef __ARCH_SI_ATTRIBUTES
#define __ARCH_SI_ATTRIBUTES
#endif
#ifndef HAVE_ARCH_SIGINFO_T
typedef struct siginfo {
int si_signo;
int si_errno;
int si_code;
union {
int _pad[SI_PAD_SIZE];
/* kill() */
struct {
__kernel_pid_t _pid; /* sender's pid */
__ARCH_SI_UID_T _uid; /* sender's uid */
} _kill;
/* POSIX.1b timers */
struct {
__kernel_timer_t _tid; /* timer id */
int _overrun; /* overrun count */
char _pad[sizeof( __ARCH_SI_UID_T) - sizeof(int)];
sigval_t _sigval; /* same as below */
int _sys_private; /* not to be passed to user */
} _timer;
/* POSIX.1b signals */
struct {
__kernel_pid_t _pid; /* sender's pid */
__ARCH_SI_UID_T _uid; /* sender's uid */
sigval_t _sigval;
} _rt;
/* SIGCHLD */
struct {
__kernel_pid_t _pid; /* which child */
__ARCH_SI_UID_T _uid; /* sender's uid */
int _status; /* exit code */
__ARCH_SI_CLOCK_T _utime;
__ARCH_SI_CLOCK_T _stime;
} _sigchld;
/* SIGILL, SIGFPE, SIGSEGV, SIGBUS */
struct {
void __user *_addr; /* faulting insn/memory ref. */
#ifdef __ARCH_SI_TRAPNO
int _trapno; /* TRAP # which caused the signal */
#endif
short _addr_lsb; /* LSB of the reported address */
union {
/* used when si_code=SEGV_BNDERR */
struct {
void __user *_lower;
void __user *_upper;
} _addr_bnd;
/* used when si_code=SEGV_PKUERR */
__u32 _pkey;
};
} _sigfault;
/* SIGPOLL */
struct {
__ARCH_SI_BAND_T _band; /* POLL_IN, POLL_OUT, POLL_MSG */
int _fd;
} _sigpoll;
/* SIGSYS */
struct {
void __user *_call_addr; /* calling user insn */
int _syscall; /* triggering system call number */
unsigned int _arch; /* AUDIT_ARCH_* of syscall */
} _sigsys;
} _sifields;
} __ARCH_SI_ATTRIBUTES siginfo_t;
/* If the arch shares siginfo, then it has SIGSYS. */
#define __ARCH_SIGSYS
#endif
/*
* How these fields are to be accessed.
*/
#define si_pid _sifields._kill._pid
#define si_uid _sifields._kill._uid
#define si_tid _sifields._timer._tid
#define si_overrun _sifields._timer._overrun
#define si_sys_private _sifields._timer._sys_private
#define si_status _sifields._sigchld._status
#define si_utime _sifields._sigchld._utime
#define si_stime _sifields._sigchld._stime
#define si_value _sifields._rt._sigval
#define si_int _sifields._rt._sigval.sival_int
#define si_ptr _sifields._rt._sigval.sival_ptr
#define si_addr _sifields._sigfault._addr
#ifdef __ARCH_SI_TRAPNO
#define si_trapno _sifields._sigfault._trapno
#endif
#define si_addr_lsb _sifields._sigfault._addr_lsb
#define si_lower _sifields._sigfault._addr_bnd._lower
#define si_upper _sifields._sigfault._addr_bnd._upper
#define si_pkey _sifields._sigfault._pkey
#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
/*
* si_code values
* Digital reserves positive values for kernel-generated signals.
*/
#define SI_USER 0 /* sent by kill, sigsend, raise */
#define SI_KERNEL 0x80 /* sent by the kernel from somewhere */
#define SI_QUEUE -1 /* sent by sigqueue */
#define SI_TIMER -2 /* sent by timer expiration */
#define SI_MESGQ -3 /* sent by real time mesq state change */
#define SI_ASYNCIO -4 /* sent by AIO completion */
#define SI_SIGIO -5 /* sent by queued SIGIO */
#define SI_TKILL -6 /* sent by tkill system call */
#define SI_DETHREAD -7 /* sent by execve() killing subsidiary threads */
#define SI_FROMUSER(siptr) ((siptr)->si_code <= 0)
#define SI_FROMKERNEL(siptr) ((siptr)->si_code > 0)
/*
* SIGILL si_codes
*/
#define ILL_ILLOPC 1 /* illegal opcode */
#define ILL_ILLOPN 2 /* illegal operand */
#define ILL_ILLADR 3 /* illegal addressing mode */
#define ILL_ILLTRP 4 /* illegal trap */
#define ILL_PRVOPC 5 /* privileged opcode */
#define ILL_PRVREG 6 /* privileged register */
#define ILL_COPROC 7 /* coprocessor error */
#define ILL_BADSTK 8 /* internal stack error */
#define NSIGILL 8
/*
* SIGFPE si_codes
*/
#define FPE_INTDIV 1 /* integer divide by zero */
#define FPE_INTOVF 2 /* integer overflow */
#define FPE_FLTDIV 3 /* floating point divide by zero */
#define FPE_FLTOVF 4 /* floating point overflow */
#define FPE_FLTUND 5 /* floating point underflow */
#define FPE_FLTRES 6 /* floating point inexact result */
#define FPE_FLTINV 7 /* floating point invalid operation */
#define FPE_FLTSUB 8 /* subscript out of range */
#define NSIGFPE 8
/*
* SIGSEGV si_codes
*/
#define SEGV_MAPERR 1 /* address not mapped to object */
#define SEGV_ACCERR 2 /* invalid permissions for mapped object */
#define SEGV_BNDERR 3 /* failed address bound checks */
#define SEGV_PKUERR 4 /* failed protection key checks */
#define NSIGSEGV 4
/*
* SIGBUS si_codes
*/
#define BUS_ADRALN 1 /* invalid address alignment */
#define BUS_ADRERR 2 /* non-existent physical address */
#define BUS_OBJERR 3 /* object specific hardware error */
/* hardware memory error consumed on a machine check: action required */
#define BUS_MCEERR_AR 4
/* hardware memory error detected in process but not consumed: action optional*/
#define BUS_MCEERR_AO 5
#define NSIGBUS 5
/*
* SIGTRAP si_codes
*/
#define TRAP_BRKPT 1 /* process breakpoint */
#define TRAP_TRACE 2 /* process trace trap */
#define TRAP_BRANCH 3 /* process taken branch trap */
#define TRAP_HWBKPT 4 /* hardware breakpoint/watchpoint */
#define NSIGTRAP 4
/*
* SIGCHLD si_codes
*/
#define CLD_EXITED 1 /* child has exited */
#define CLD_KILLED 2 /* child was killed */
#define CLD_DUMPED 3 /* child terminated abnormally */
#define CLD_TRAPPED 4 /* traced child has trapped */
#define CLD_STOPPED 5 /* child has stopped */
#define CLD_CONTINUED 6 /* stopped child has continued */
#define NSIGCHLD 6
/*
* SIGPOLL (or any other signal without signal specific si_codes) si_codes
*/
#define POLL_IN 1 /* data input available */
#define POLL_OUT 2 /* output buffers available */
#define POLL_MSG 3 /* input message available */
#define POLL_ERR 4 /* i/o error */
#define POLL_PRI 5 /* high priority input available */
#define POLL_HUP 6 /* device disconnected */
#define NSIGPOLL 6
/*
* SIGSYS si_codes
*/
#define SYS_SECCOMP 1 /* seccomp triggered */
#define NSIGSYS 1
/*
* sigevent definitions
*
* It seems likely that SIGEV_THREAD will have to be handled from
* userspace, libpthread transmuting it to SIGEV_SIGNAL, which the
* thread manager then catches and does the appropriate nonsense.
* However, everything is written out here so as to not get lost.
*/
#define SIGEV_SIGNAL 0 /* notify via signal */
#define SIGEV_NONE 1 /* other notification: meaningless */
#define SIGEV_THREAD 2 /* deliver via thread creation */
#define SIGEV_THREAD_ID 4 /* deliver to thread */
/*
* This works because the alignment is ok on all current architectures
* but we leave open this being overridden in the future
*/
#ifndef __ARCH_SIGEV_PREAMBLE_SIZE
#define __ARCH_SIGEV_PREAMBLE_SIZE (sizeof(int) * 2 + sizeof(sigval_t))
#endif
#define SIGEV_MAX_SIZE 64
#define SIGEV_PAD_SIZE ((SIGEV_MAX_SIZE - __ARCH_SIGEV_PREAMBLE_SIZE) \
/ sizeof(int))
typedef struct sigevent {
sigval_t sigev_value;
int sigev_signo;
int sigev_notify;
union {
int _pad[SIGEV_PAD_SIZE];
int _tid;
struct {
void (*_function)(sigval_t);
void *_attribute; /* really pthread_attr_t */
} _sigev_thread;
} _sigev_un;
} sigevent_t;
#define sigev_notify_function _sigev_un._sigev_thread._function
#define sigev_notify_attributes _sigev_un._sigev_thread._attribute
#define sigev_notify_thread_id _sigev_un._tid
#endif /* _UAPI_ASM_GENERIC_SIGINFO_H */