summaryrefslogtreecommitdiff
path: root/arch/blackfin/include
diff options
context:
space:
mode:
authorEric W. Biederman <ebiederm@xmission.com>2017-07-17 06:36:59 +0300
committerEric W. Biederman <ebiederm@xmission.com>2017-07-24 22:30:28 +0300
commitcc731525f26af85a1c3537da41e0abd1d35e0bdb (patch)
tree5badfc64a4a161cc6bc869ca376b019aaa937d2f /arch/blackfin/include
parentd08477aa975e97f1dc64c0ae59cebf98520456ce (diff)
downloadlinux-cc731525f26af85a1c3537da41e0abd1d35e0bdb.tar.xz
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 'arch/blackfin/include')
-rw-r--r--arch/blackfin/include/uapi/asm/siginfo.h30
1 files changed, 19 insertions, 11 deletions
diff --git a/arch/blackfin/include/uapi/asm/siginfo.h b/arch/blackfin/include/uapi/asm/siginfo.h
index c72f4e6e386f..79dfe3979123 100644
--- a/arch/blackfin/include/uapi/asm/siginfo.h
+++ b/arch/blackfin/include/uapi/asm/siginfo.h
@@ -14,28 +14,36 @@
#define si_uid16 _sifields._kill._uid
-#define ILL_ILLPARAOP (__SI_FAULT|2) /* illegal opcode combine ********** */
-#define ILL_ILLEXCPT (__SI_FAULT|4) /* unrecoverable exception ********** */
-#define ILL_CPLB_VI (__SI_FAULT|9) /* D/I CPLB protect violation ******** */
-#define ILL_CPLB_MISS (__SI_FAULT|10) /* D/I CPLB miss ******** */
-#define ILL_CPLB_MULHIT (__SI_FAULT|11) /* D/I CPLB multiple hit ******** */
+#define ILL_ILLPARAOP 2 /* illegal opcode combine ********** */
+#define ILL_ILLEXCPT 4 /* unrecoverable exception ********** */
+#define ILL_CPLB_VI 9 /* D/I CPLB protect violation ******** */
+#define ILL_CPLB_MISS 10 /* D/I CPLB miss ******** */
+#define ILL_CPLB_MULHIT 11 /* D/I CPLB multiple hit ******** */
+#undef NSIGILL
+#define NSIGILL 11
/*
* SIGBUS si_codes
*/
-#define BUS_OPFETCH (__SI_FAULT|4) /* error from instruction fetch ******** */
+#define BUS_OPFETCH 4 /* error from instruction fetch ******** */
+#undef NSIGBUS
+#define NSIGBUS 4
/*
* SIGTRAP si_codes
*/
-#define TRAP_STEP (__SI_FAULT|1) /* single-step breakpoint************* */
-#define TRAP_TRACEFLOW (__SI_FAULT|2) /* trace buffer overflow ************* */
-#define TRAP_WATCHPT (__SI_FAULT|3) /* watchpoint match ************* */
-#define TRAP_ILLTRAP (__SI_FAULT|4) /* illegal trap ************* */
+#define TRAP_STEP 1 /* single-step breakpoint************* */
+#define TRAP_TRACEFLOW 2 /* trace buffer overflow ************* */
+#define TRAP_WATCHPT 3 /* watchpoint match ************* */
+#define TRAP_ILLTRAP 4 /* illegal trap ************* */
+#undef NSIGTRAP
+#define NSIGTRAP 4
/*
* SIGSEGV si_codes
*/
-#define SEGV_STACKFLOW (__SI_FAULT|3) /* stack overflow */
+#define SEGV_STACKFLOW 3 /* stack overflow */
+#undef NSIGSEGV
+#define NSIGSEGV 3
#endif /* _UAPI_BFIN_SIGINFO_H */