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authorEric W. Biederman <ebiederm@xmission.com>2017-07-16 22:36:59 -0500
committerEric W. Biederman <ebiederm@xmission.com>2017-07-24 14:30:28 -0500
commitcc731525f26af85a1c3537da41e0abd1d35e0bdb (patch)
tree5badfc64a4a161cc6bc869ca376b019aaa937d2f /include/uapi/asm-generic
parentd08477aa975e97f1dc64c0ae59cebf98520456ce (diff)
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>
Diffstat (limited to 'include/uapi/asm-generic')
-rw-r--r--include/uapi/asm-generic/siginfo.h115
1 files changed, 46 insertions, 69 deletions
diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
index 9e956ea94d57..e5aa6794cea4 100644
--- a/include/uapi/asm-generic/siginfo.h
+++ b/include/uapi/asm-generic/siginfo.h
@@ -151,29 +151,6 @@ typedef struct siginfo {
#define si_arch _sifields._sigsys._arch
#endif
-#ifdef __KERNEL__
-#define __SI_MASK 0xffff0000u
-#define __SI_KILL (0 << 16)
-#define __SI_TIMER (1 << 16)
-#define __SI_POLL (2 << 16)
-#define __SI_FAULT (3 << 16)
-#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 /* __KERNEL__ */
-#define __SI_KILL 0
-#define __SI_TIMER 0
-#define __SI_POLL 0
-#define __SI_FAULT 0
-#define __SI_CHLD 0
-#define __SI_RT 0
-#define __SI_MESGQ 0
-#define __SI_SYS 0
-#define __SI_CODE(T,N) (N)
-#endif /* __KERNEL__ */
-
/*
* si_code values
* Digital reserves positive values for kernel-generated signals.
@@ -181,10 +158,10 @@ typedef struct siginfo {
#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 __SI_CODE(__SI_TIMER,-2) /* sent by timer expiration */
-#define SI_MESGQ __SI_CODE(__SI_MESGQ,-3) /* sent by real time mesq state change */
+#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 __SI_CODE(__SI_POLL,-5) /* sent by queued SIGIO */
+#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 */
@@ -194,86 +171,86 @@ typedef struct siginfo {
/*
* SIGILL si_codes
*/
-#define ILL_ILLOPC (__SI_FAULT|1) /* illegal opcode */
-#define ILL_ILLOPN (__SI_FAULT|2) /* illegal operand */
-#define ILL_ILLADR (__SI_FAULT|3) /* illegal addressing mode */
-#define ILL_ILLTRP (__SI_FAULT|4) /* illegal trap */
-#define ILL_PRVOPC (__SI_FAULT|5) /* privileged opcode */
-#define ILL_PRVREG (__SI_FAULT|6) /* privileged register */
-#define ILL_COPROC (__SI_FAULT|7) /* coprocessor error */
-#define ILL_BADSTK (__SI_FAULT|8) /* internal stack error */
+#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 (__SI_FAULT|1) /* integer divide by zero */
-#define FPE_INTOVF (__SI_FAULT|2) /* integer overflow */
-#define FPE_FLTDIV (__SI_FAULT|3) /* floating point divide by zero */
-#define FPE_FLTOVF (__SI_FAULT|4) /* floating point overflow */
-#define FPE_FLTUND (__SI_FAULT|5) /* floating point underflow */
-#define FPE_FLTRES (__SI_FAULT|6) /* floating point inexact result */
-#define FPE_FLTINV (__SI_FAULT|7) /* floating point invalid operation */
-#define FPE_FLTSUB (__SI_FAULT|8) /* subscript out of range */
+#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 (__SI_FAULT|1) /* address not mapped to object */
-#define SEGV_ACCERR (__SI_FAULT|2) /* invalid permissions for mapped object */
-#define SEGV_BNDERR (__SI_FAULT|3) /* failed address bound checks */
-#define SEGV_PKUERR (__SI_FAULT|4) /* failed protection key checks */
+#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 (__SI_FAULT|1) /* invalid address alignment */
-#define BUS_ADRERR (__SI_FAULT|2) /* non-existent physical address */
-#define BUS_OBJERR (__SI_FAULT|3) /* object specific hardware error */
+#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 (__SI_FAULT|4)
+#define BUS_MCEERR_AR 4
/* hardware memory error detected in process but not consumed: action optional*/
-#define BUS_MCEERR_AO (__SI_FAULT|5)
+#define BUS_MCEERR_AO 5
#define NSIGBUS 5
/*
* SIGTRAP si_codes
*/
-#define TRAP_BRKPT (__SI_FAULT|1) /* process breakpoint */
-#define TRAP_TRACE (__SI_FAULT|2) /* process trace trap */
-#define TRAP_BRANCH (__SI_FAULT|3) /* process taken branch trap */
-#define TRAP_HWBKPT (__SI_FAULT|4) /* hardware breakpoint/watchpoint */
+#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 (__SI_CHLD|1) /* child has exited */
-#define CLD_KILLED (__SI_CHLD|2) /* child was killed */
-#define CLD_DUMPED (__SI_CHLD|3) /* child terminated abnormally */
-#define CLD_TRAPPED (__SI_CHLD|4) /* traced child has trapped */
-#define CLD_STOPPED (__SI_CHLD|5) /* child has stopped */
-#define CLD_CONTINUED (__SI_CHLD|6) /* stopped child has continued */
+#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 (__SI_POLL|1) /* data input available */
-#define POLL_OUT (__SI_POLL|2) /* output buffers available */
-#define POLL_MSG (__SI_POLL|3) /* input message available */
-#define POLL_ERR (__SI_POLL|4) /* i/o error */
-#define POLL_PRI (__SI_POLL|5) /* high priority input available */
-#define POLL_HUP (__SI_POLL|6) /* device disconnected */
+#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 (__SI_SYS|1) /* seccomp triggered */
-#define NSIGSYS 1
+#define SYS_SECCOMP 1 /* seccomp triggered */
+#define NSIGSYS 1
/*
* sigevent definitions

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