This allows userspace to detect missing support for flag bits and allows the kernel to use non-uapi bits internally, as we are already doing in arch/x86 for two flag bits. Now that this change is in place, we no longer need the code in arch/x86 that was hiding these bits from userspace, so remove it. Signed-off-by: Peter Collingbourne <pcc@xxxxxxxxxx> --- View this change in Gerrit: https://linux-review.googlesource.com/q/I35aab6f5be932505d90f3b3450c083b4db1eca86 arch/arm/include/asm/signal.h | 4 ++++ arch/parisc/include/asm/signal.h | 4 ++++ arch/x86/kernel/signal_compat.c | 7 ------- include/linux/signal_types.h | 12 ++++++++++++ kernel/signal.c | 10 ++++++++++ 5 files changed, 30 insertions(+), 7 deletions(-) diff --git a/arch/arm/include/asm/signal.h b/arch/arm/include/asm/signal.h index 65530a042009..d1070a783993 100644 --- a/arch/arm/include/asm/signal.h +++ b/arch/arm/include/asm/signal.h @@ -17,6 +17,10 @@ typedef struct { unsigned long sig[_NSIG_WORDS]; } sigset_t; +#define SA_UAPI_FLAGS \ + (SA_NOCLDSTOP | SA_NOCLDWAIT | SA_SIGINFO | SA_THIRTYTWO | \ + SA_RESTORER | SA_ONSTACK | SA_RESTART | SA_NODEFER | SA_RESETHAND) + #define __ARCH_HAS_SA_RESTORER #include <asm/sigcontext.h> diff --git a/arch/parisc/include/asm/signal.h b/arch/parisc/include/asm/signal.h index 715c96ba2ec8..ad06e14f6e8a 100644 --- a/arch/parisc/include/asm/signal.h +++ b/arch/parisc/include/asm/signal.h @@ -21,6 +21,10 @@ typedef struct { unsigned long sig[_NSIG_WORDS]; } sigset_t; +#define SA_UAPI_FLAGS \ + (SA_ONSTACK | SA_RESETHAND | SA_NOCLDSTOP | SA_SIGINFO | SA_NODEFER | \ + SA_RESTART | SA_NOCLDWAIT | _SA_SIGGFAULT) + #include <asm/sigcontext.h> #endif /* !__ASSEMBLY */ diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c index 9ccbf0576cd0..c599013ae8cb 100644 --- a/arch/x86/kernel/signal_compat.c +++ b/arch/x86/kernel/signal_compat.c @@ -165,16 +165,9 @@ void sigaction_compat_abi(struct k_sigaction *act, struct k_sigaction *oact) { signal_compat_build_tests(); - /* Don't leak in-kernel non-uapi flags to user-space */ - if (oact) - oact->sa.sa_flags &= ~(SA_IA32_ABI | SA_X32_ABI); - if (!act) return; - /* Don't let flags to be set from userspace */ - act->sa.sa_flags &= ~(SA_IA32_ABI | SA_X32_ABI); - if (in_ia32_syscall()) act->sa.sa_flags |= SA_IA32_ABI; if (in_x32_syscall()) diff --git a/include/linux/signal_types.h b/include/linux/signal_types.h index f8a90ae9c6ec..e792f29b5846 100644 --- a/include/linux/signal_types.h +++ b/include/linux/signal_types.h @@ -68,4 +68,16 @@ struct ksignal { int sig; }; +#ifndef SA_UAPI_FLAGS +#ifdef SA_RESTORER +#define SA_UAPI_FLAGS \ + (SA_NOCLDSTOP | SA_NOCLDWAIT | SA_SIGINFO | SA_ONSTACK | SA_RESTART | \ + SA_NODEFER | SA_RESETHAND | SA_RESTORER) +#else +#define SA_UAPI_FLAGS \ + (SA_NOCLDSTOP | SA_NOCLDWAIT | SA_SIGINFO | SA_ONSTACK | SA_RESTART | \ + SA_NODEFER | SA_RESETHAND) +#endif +#endif + #endif /* _LINUX_SIGNAL_TYPES_H */ diff --git a/kernel/signal.c b/kernel/signal.c index 42b67d2cea37..348b7981f1ff 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -3984,6 +3984,16 @@ int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact) if (oact) *oact = *k; + /* + * Clear unknown flag bits in order to allow userspace to detect missing + * support for flag bits and to allow the kernel to use non-uapi bits + * internally. + */ + if (act) + act->sa.sa_flags &= SA_UAPI_FLAGS; + if (oact) + oact->sa.sa_flags &= SA_UAPI_FLAGS; + sigaction_compat_abi(act, oact); if (act) { -- 2.28.0.220.ged08abb693-goog
