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a54f0dfda7
Define a sa_flags bit, SA_UNSUPPORTED, which will never be supported in the uapi. The purpose of this flag bit is to allow userspace to distinguish an old kernel that does not clear unknown sa_flags bits from a kernel that supports every flag bit. In other words, if userspace does something like: act.sa_flags |= SA_UNSUPPORTED; sigaction(SIGSEGV, &act, 0); sigaction(SIGSEGV, 0, &oldact); and finds that SA_UNSUPPORTED remains set in oldact.sa_flags, it means that the kernel cannot be trusted to have cleared unknown flag bits from sa_flags, so no assumptions about flag bit support can be made. Signed-off-by: Peter Collingbourne <pcc@google.com> Reviewed-by: Dave Martin <Dave.Martin@arm.com> Link: https://linux-review.googlesource.com/id/Ic2501ad150a3a79c1cf27fb8c99be342e9dffbcb Link: https://lkml.kernel.org/r/bda7ddff8895a9bc4ffc5f3cf3d4d37a32118077.1605582887.git.pcc@google.com Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
89 lines
2.7 KiB
C
89 lines
2.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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#ifndef __ASM_GENERIC_SIGNAL_DEFS_H
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#define __ASM_GENERIC_SIGNAL_DEFS_H
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#include <linux/compiler.h>
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/*
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* SA_FLAGS values:
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*
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* SA_NOCLDSTOP flag to turn off SIGCHLD when children stop.
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* SA_NOCLDWAIT flag on SIGCHLD to inhibit zombies.
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* SA_SIGINFO delivers the signal with SIGINFO structs.
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* SA_ONSTACK indicates that a registered stack_t will be used.
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* SA_RESTART flag to get restarting signals (which were the default long ago)
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* SA_NODEFER prevents the current signal from being masked in the handler.
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* SA_RESETHAND clears the handler when the signal is delivered.
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* SA_UNSUPPORTED is a flag bit that will never be supported. Kernels from
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* before the introduction of SA_UNSUPPORTED did not clear unknown bits from
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* sa_flags when read using the oldact argument to sigaction and rt_sigaction,
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* so this bit allows flag bit support to be detected from userspace while
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* allowing an old kernel to be distinguished from a kernel that supports every
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* flag bit.
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*
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* SA_ONESHOT and SA_NOMASK are the historical Linux names for the Single
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* Unix names RESETHAND and NODEFER respectively.
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*/
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#ifndef SA_NOCLDSTOP
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#define SA_NOCLDSTOP 0x00000001
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#endif
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#ifndef SA_NOCLDWAIT
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#define SA_NOCLDWAIT 0x00000002
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#endif
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#ifndef SA_SIGINFO
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#define SA_SIGINFO 0x00000004
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#endif
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/* 0x00000008 used on alpha, mips, parisc */
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/* 0x00000010 used on alpha, parisc */
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/* 0x00000020 used on alpha, parisc, sparc */
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/* 0x00000040 used on alpha, parisc */
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/* 0x00000080 used on parisc */
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/* 0x00000100 used on sparc */
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/* 0x00000200 used on sparc */
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#define SA_UNSUPPORTED 0x00000400
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/* 0x00010000 used on mips */
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/* 0x01000000 used on x86 */
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/* 0x02000000 used on x86 */
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/*
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* New architectures should not define the obsolete
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* SA_RESTORER 0x04000000
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*/
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#ifndef SA_ONSTACK
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#define SA_ONSTACK 0x08000000
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#endif
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#ifndef SA_RESTART
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#define SA_RESTART 0x10000000
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#endif
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#ifndef SA_NODEFER
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#define SA_NODEFER 0x40000000
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#endif
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#ifndef SA_RESETHAND
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#define SA_RESETHAND 0x80000000
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#endif
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#define SA_NOMASK SA_NODEFER
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#define SA_ONESHOT SA_RESETHAND
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#ifndef SIG_BLOCK
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#define SIG_BLOCK 0 /* for blocking signals */
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#endif
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#ifndef SIG_UNBLOCK
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#define SIG_UNBLOCK 1 /* for unblocking signals */
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#endif
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#ifndef SIG_SETMASK
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#define SIG_SETMASK 2 /* for setting the signal mask */
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#endif
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#ifndef __ASSEMBLY__
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typedef void __signalfn_t(int);
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typedef __signalfn_t __user *__sighandler_t;
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typedef void __restorefn_t(void);
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typedef __restorefn_t __user *__sigrestore_t;
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#define SIG_DFL ((__force __sighandler_t)0) /* default signal handling */
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#define SIG_IGN ((__force __sighandler_t)1) /* ignore signal */
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#define SIG_ERR ((__force __sighandler_t)-1) /* error return from signal */
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#endif
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#endif /* __ASM_GENERIC_SIGNAL_DEFS_H */
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