Merge branch 'exit-cleanups-for-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

Pull exit cleanups from Eric Biederman:
 "In preparation of doing something about PTRACE_EVENT_EXIT I have
  started cleaning up various pieces of code related to do_exit. Most of
  that code I did not manage to get tested and reviewed before the merge
  window opened but a handful of very useful cleanups are ready to be
  merged.

  The first change is simply the removal of the bdflush system call. The
  code has now been disabled long enough that even the oldest userspace
  working userspace setups anyone can find to test are fine with the
  bdflush system call being removed.

  Changing m68k fsp040_die to use force_sigsegv(SIGSEGV) instead of
  calling do_exit directly is interesting only in that it is nearly the
  most difficult of the incorrect uses of do_exit to remove.

  The change to the seccomp code to simply send a signal instead of
  calling do_coredump directly is a very nice little cleanup made
  possible by realizing the existing signal sending helpers were missing
  a little bit of functionality that is easy to provide"

* 'exit-cleanups-for-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  signal/seccomp: Dump core when there is only one live thread
  signal/seccomp: Refactor seccomp signal and coredump generation
  signal/m68k: Use force_sigsegv(SIGSEGV) in fpsp040_die
  exit/bdflush: Remove the deprecated bdflush system call

25 files changed, 53 insertions, 87 deletions

diff --git a/arch/alpha/kernel/syscalls/syscall.tbl b/arch/alpha/kernel/syscalls/syscall.tbl
index a17687ed4b51..7ac22e007d52 100644
--- a/arch/alpha/kernel/syscalls/syscall.tbl
+++ b/arch/alpha/kernel/syscalls/syscall.tbl
@@ -230,7 +230,7 @@
 259	common	osf_swapctl			sys_ni_syscall
 260	common	osf_memcntl			sys_ni_syscall
 261	common	osf_fdatasync			sys_ni_syscall
-300	common	bdflush				sys_bdflush
+300	common	bdflush				sys_ni_syscall
 301	common	sethae				sys_sethae
 302	common	mount				sys_mount
 303	common	old_adjtimex			sys_old_adjtimex
diff --git a/arch/arm/tools/syscall.tbl b/arch/arm/tools/syscall.tbl
index c5df1179fc5d..f8a2d5aa17b7 100644
--- a/arch/arm/tools/syscall.tbl
+++ b/arch/arm/tools/syscall.tbl
@@ -147,7 +147,7 @@
 131	common	quotactl		sys_quotactl
 132	common	getpgid			sys_getpgid
 133	common	fchdir			sys_fchdir
-134	common	bdflush			sys_bdflush
+134	common	bdflush			sys_ni_syscall
 135	common	sysfs			sys_sysfs
 136	common	personality		sys_personality
 # 137 was sys_afs_syscall
diff --git a/arch/arm64/include/asm/unistd32.h b/arch/arm64/include/asm/unistd32.h
index 99ffcafc736c..03d4ca47d253 100644
--- a/arch/arm64/include/asm/unistd32.h
+++ b/arch/arm64/include/asm/unistd32.h
@@ -279,7 +279,7 @@ __SYSCALL(__NR_getpgid, sys_getpgid)
 #define __NR_fchdir 133
 __SYSCALL(__NR_fchdir, sys_fchdir)
 #define __NR_bdflush 134
-__SYSCALL(__NR_bdflush, sys_bdflush)
+__SYSCALL(__NR_bdflush, sys_ni_syscall)
 #define __NR_sysfs 135
 __SYSCALL(__NR_sysfs, sys_sysfs)
 #define __NR_personality 136
diff --git a/arch/ia64/kernel/syscalls/syscall.tbl b/arch/ia64/kernel/syscalls/syscall.tbl
index 6d07742c57b8..4b20224b14d9 100644
--- a/arch/ia64/kernel/syscalls/syscall.tbl
+++ b/arch/ia64/kernel/syscalls/syscall.tbl
@@ -123,7 +123,7 @@
 # 1135 was get_kernel_syms
 # 1136 was query_module
 113	common	quotactl			sys_quotactl
-114	common	bdflush				sys_bdflush
+114	common	bdflush				sys_ni_syscall
 115	common	sysfs				sys_sysfs
 116	common	personality			sys_personality
 117	common	afs_syscall			sys_ni_syscall
diff --git a/arch/m68k/fpsp040/skeleton.S b/arch/m68k/fpsp040/skeleton.S
index a8f41615d94a..439395aa6fb4 100644
--- a/arch/m68k/fpsp040/skeleton.S
+++ b/arch/m68k/fpsp040/skeleton.S
@@ -502,7 +502,8 @@ in_ea:
 	.section .fixup,#alloc,#execinstr
 	.even
 1:
-	jbra	fpsp040_die
+	jbsr	fpsp040_die
+	jbra	.Lnotkern
 
 	.section __ex_table,#alloc
 	.align	4
diff --git a/arch/m68k/kernel/syscalls/syscall.tbl b/arch/m68k/kernel/syscalls/syscall.tbl
index 541bc1b3a8f9..3ec1291c268d 100644
--- a/arch/m68k/kernel/syscalls/syscall.tbl
+++ b/arch/m68k/kernel/syscalls/syscall.tbl
@@ -141,7 +141,7 @@
 131	common	quotactl			sys_quotactl
 132	common	getpgid				sys_getpgid
 133	common	fchdir				sys_fchdir
-134	common	bdflush				sys_bdflush
+134	common	bdflush				sys_ni_syscall
 135	common	sysfs				sys_sysfs
 136	common	personality			sys_personality
 # 137 was afs_syscall
diff --git a/arch/m68k/kernel/traps.c b/arch/m68k/kernel/traps.c
index 9e1261462bcc..5b19fcdcd69e 100644
--- a/arch/m68k/kernel/traps.c
+++ b/arch/m68k/kernel/traps.c
@@ -1150,7 +1150,7 @@ asmlinkage void set_esp0(unsigned long ssp)
  */
 asmlinkage void fpsp040_die(void)
 {
-	do_exit(SIGSEGV);
+	force_sigsegv(SIGSEGV);
 }
 
 #ifdef CONFIG_M68KFPU_EMU
diff --git a/arch/microblaze/kernel/syscalls/syscall.tbl b/arch/microblaze/kernel/syscalls/syscall.tbl
index a176faca2927..9be3ace12938 100644
--- a/arch/microblaze/kernel/syscalls/syscall.tbl
+++ b/arch/microblaze/kernel/syscalls/syscall.tbl
@@ -141,7 +141,7 @@
 131	common	quotactl			sys_quotactl
 132	common	getpgid				sys_getpgid
 133	common	fchdir				sys_fchdir
-134	common	bdflush				sys_bdflush
+134	common	bdflush				sys_ni_syscall
 135	common	sysfs				sys_sysfs
 136	common	personality			sys_personality
 137	common	afs_syscall			sys_ni_syscall
diff --git a/arch/mips/kernel/syscalls/syscall_o32.tbl b/arch/mips/kernel/syscalls/syscall_o32.tbl
index 253f2cd70b6b..fae35882a165 100644
--- a/arch/mips/kernel/syscalls/syscall_o32.tbl
+++ b/arch/mips/kernel/syscalls/syscall_o32.tbl
@@ -145,7 +145,7 @@
 131	o32	quotactl			sys_quotactl
 132	o32	getpgid				sys_getpgid
 133	o32	fchdir				sys_fchdir
-134	o32	bdflush				sys_bdflush
+134	o32	bdflush				sys_ni_syscall
 135	o32	sysfs				sys_sysfs
 136	o32	personality			sys_personality			sys_32_personality
 137	o32	afs_syscall			sys_ni_syscall
diff --git a/arch/parisc/kernel/syscalls/syscall.tbl b/arch/parisc/kernel/syscalls/syscall.tbl
index e26187b9ab87..eaf0603ae781 100644
--- a/arch/parisc/kernel/syscalls/syscall.tbl
+++ b/arch/parisc/kernel/syscalls/syscall.tbl
@@ -147,7 +147,7 @@
 131	common	quotactl		sys_quotactl
 132	common	getpgid			sys_getpgid
 133	common	fchdir			sys_fchdir
-134	common	bdflush			sys_bdflush
+134	common	bdflush			sys_ni_syscall
 135	common	sysfs			sys_sysfs
 136	32	personality		parisc_personality
 136	64	personality		sys_personality
diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl
index aef2a290e71a..6f3953f2a0d5 100644
--- a/arch/powerpc/kernel/syscalls/syscall.tbl
+++ b/arch/powerpc/kernel/syscalls/syscall.tbl
@@ -176,7 +176,7 @@
 131	nospu	quotactl			sys_quotactl
 132	common	getpgid				sys_getpgid
 133	common	fchdir				sys_fchdir
-134	common	bdflush				sys_bdflush
+134	common	bdflush				sys_ni_syscall
 135	common	sysfs				sys_sysfs
 136	32	personality			sys_personality			ppc64_personality
 136	64	personality			ppc64_personality
diff --git a/arch/s390/kernel/syscalls/syscall.tbl b/arch/s390/kernel/syscalls/syscall.tbl
index 64d51ab5a8b4..aa705e1bd0dc 100644
--- a/arch/s390/kernel/syscalls/syscall.tbl
+++ b/arch/s390/kernel/syscalls/syscall.tbl
@@ -122,7 +122,7 @@
 131  common	quotactl		sys_quotactl			sys_quotactl
 132  common	getpgid			sys_getpgid			sys_getpgid
 133  common	fchdir			sys_fchdir			sys_fchdir
-134  common	bdflush			sys_bdflush			sys_bdflush
+134  common	bdflush			sys_ni_syscall			sys_ni_syscall
 135  common	sysfs			sys_sysfs			sys_sysfs
 136  common	personality		sys_s390_personality		sys_s390_personality
 137  common	afs_syscall		-				-
diff --git a/arch/sh/kernel/syscalls/syscall.tbl b/arch/sh/kernel/syscalls/syscall.tbl
index e0a70be77d84..7bbd6700ae4b 100644
--- a/arch/sh/kernel/syscalls/syscall.tbl
+++ b/arch/sh/kernel/syscalls/syscall.tbl
@@ -141,7 +141,7 @@
 131	common	quotactl			sys_quotactl
 132	common	getpgid				sys_getpgid
 133	common	fchdir				sys_fchdir
-134	common	bdflush				sys_bdflush
+134	common	bdflush				sys_ni_syscall
 135	common	sysfs				sys_sysfs
 136	common	personality			sys_personality
 # 137 was afs_syscall
diff --git a/arch/sparc/kernel/syscalls/syscall.tbl b/arch/sparc/kernel/syscalls/syscall.tbl
index 603f5a821502..f520e9cd2c78 100644
--- a/arch/sparc/kernel/syscalls/syscall.tbl
+++ b/arch/sparc/kernel/syscalls/syscall.tbl
@@ -270,7 +270,7 @@
 222	common	delete_module		sys_delete_module
 223	common	get_kernel_syms		sys_ni_syscall
 224	common	getpgid			sys_getpgid
-225	common	bdflush			sys_bdflush
+225	common	bdflush			sys_ni_syscall
 226	common	sysfs			sys_sysfs
 227	common	afs_syscall		sys_nis_syscall
 228	common	setfsuid		sys_setfsuid16
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index ce763a12311c..a5beae6daf20 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -145,7 +145,7 @@
 131	i386	quotactl		sys_quotactl
 132	i386	getpgid			sys_getpgid
 133	i386	fchdir			sys_fchdir
-134	i386	bdflush			sys_bdflush
+134	i386	bdflush			sys_ni_syscall
 135	i386	sysfs			sys_sysfs
 136	i386	personality		sys_personality
 137	i386	afs_syscall
diff --git a/arch/xtensa/kernel/syscalls/syscall.tbl b/arch/xtensa/kernel/syscalls/syscall.tbl
index 235d67d6ceb4..b3d1bc8a9095 100644
--- a/arch/xtensa/kernel/syscalls/syscall.tbl
+++ b/arch/xtensa/kernel/syscalls/syscall.tbl
@@ -223,7 +223,7 @@
 # 205 was old nfsservctl
 205	common	nfsservctl			sys_ni_syscall
 206	common	_sysctl				sys_ni_syscall
-207	common	bdflush				sys_bdflush
+207	common	bdflush				sys_ni_syscall
 208	common	uname				sys_newuname
 209	common	sysinfo				sys_sysinfo
 210	common	init_module			sys_init_module
diff --git a/fs/buffer.c b/fs/buffer.c
index bd6a9e9fbd64..ab7573d72dd7 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -3268,33 +3268,6 @@ out:
 EXPORT_SYMBOL(try_to_free_buffers);
 
 /*
- * There are no bdflush tunables left.  But distributions are
- * still running obsolete flush daemons, so we terminate them here.
- *
- * Use of bdflush() is deprecated and will be removed in a future kernel.
- * The `flush-X' kernel threads fully replace bdflush daemons and this call.
- */
-SYSCALL_DEFINE2(bdflush, int, func, long, data)
-{
-	static int msg_count;
-
-	if (!capable(CAP_SYS_ADMIN))
-		return -EPERM;
-
-	if (msg_count < 5) {
-		msg_count++;
-		printk(KERN_INFO
-			"warning: process `%s' used the obsolete bdflush"
-			" system call\n", current->comm);
-		printk(KERN_INFO "Fix your initscripts?\n");
-	}
-
-	if (func == 1)
-		do_exit(0);
-	return 0;
-}
-
-/*
  * Buffer-head allocation
  */
 static struct kmem_cache *bh_cachep __read_mostly;
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 548986c7d233..e5f4ce622ee6 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -324,6 +324,7 @@ int force_sig_ptrace_errno_trap(int errno, void __user *addr);
 int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
 int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
 			struct task_struct *t);
+int force_sig_seccomp(int syscall, int reason, bool force_coredump);
 
 extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
 extern void force_sigsegv(int sig);
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 69c9a7010081..2b47584eb843 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -1158,7 +1158,6 @@ asmlinkage long sys_ustat(unsigned dev, struct ustat __user *ubuf);
 asmlinkage long sys_vfork(void);
 asmlinkage long sys_recv(int, void __user *, size_t, unsigned);
 asmlinkage long sys_send(int, void __user *, size_t, unsigned);
-asmlinkage long sys_bdflush(int func, long data);
 asmlinkage long sys_oldumount(char __user *name);
 asmlinkage long sys_uselib(const char __user *library);
 asmlinkage long sys_sysfs(int option,
diff --git a/include/uapi/linux/capability.h b/include/uapi/linux/capability.h
index 2ddb4226cd23..463d1ba2232a 100644
--- a/include/uapi/linux/capability.h
+++ b/include/uapi/linux/capability.h
@@ -243,7 +243,6 @@ struct vfs_ns_cap_data {
 /* Allow examination and configuration of disk quotas */
 /* Allow setting the domainname */
 /* Allow setting the hostname */
-/* Allow calling bdflush() */
 /* Allow mount() and umount(), setting up new smb connection */
 /* Allow some autofs root ioctls */
 /* Allow nfsservctl */
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 6469eca8078c..4d8f44a17727 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -922,30 +922,6 @@ void get_seccomp_filter(struct task_struct *tsk)
 	refcount_inc(&orig->users);
 }
 
-static void seccomp_init_siginfo(kernel_siginfo_t *info, int syscall, int reason)
-{
-	clear_siginfo(info);
-	info->si_signo = SIGSYS;
-	info->si_code = SYS_SECCOMP;
-	info->si_call_addr = (void __user *)KSTK_EIP(current);
-	info->si_errno = reason;
-	info->si_arch = syscall_get_arch(current);
-	info->si_syscall = syscall;
-}
-
-/**
- * seccomp_send_sigsys - signals the task to allow in-process syscall emulation
- * @syscall: syscall number to send to userland
- * @reason: filter-supplied reason code to send to userland (via si_errno)
- *
- * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
- */
-static void seccomp_send_sigsys(int syscall, int reason)
-{
-	struct kernel_siginfo info;
-	seccomp_init_siginfo(&info, syscall, reason);
-	force_sig_info(&info);
-}
 #endif	/* CONFIG_SECCOMP_FILTER */
 
 /* For use with seccomp_actions_logged */
@@ -1218,7 +1194,7 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
 		/* Show the handler the original registers. */
 		syscall_rollback(current, current_pt_regs());
 		/* Let the filter pass back 16 bits of data. */
-		seccomp_send_sigsys(this_syscall, data);
+		force_sig_seccomp(this_syscall, data, false);
 		goto skip;
 
 	case SECCOMP_RET_TRACE:
@@ -1288,19 +1264,15 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
 		seccomp_log(this_syscall, SIGSYS, action, true);
 		/* Dump core only if this is the last remaining thread. */
 		if (action != SECCOMP_RET_KILL_THREAD ||
-		    get_nr_threads(current) == 1) {
-			kernel_siginfo_t info;
-
+		    (atomic_read(&current->signal->live) == 1)) {
 			/* Show the original registers in the dump. */
 			syscall_rollback(current, current_pt_regs());
-			/* Trigger a manual coredump since do_exit skips it. */
-			seccomp_init_siginfo(&info, this_syscall, data);
-			do_coredump(&info);
-		}
-		if (action == SECCOMP_RET_KILL_THREAD)
+			/* Trigger a coredump with SIGSYS */
+			force_sig_seccomp(this_syscall, data, true);
+		} else {
 			do_exit(SIGSYS);
-		else
-			do_group_exit(SIGSYS);
+		}
+		return -1; /* skip the syscall go directly to signal handling */
 	}
 
 	unreachable();
diff --git a/kernel/signal.c b/kernel/signal.c
index 65a54118ac9e..cf7e2505ae31 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -54,6 +54,7 @@
 #include <asm/unistd.h>
 #include <asm/siginfo.h>
 #include <asm/cacheflush.h>
+#include <asm/syscall.h>	/* for syscall_get_* */
 
 /*
  * SLAB caches for signal bits.
@@ -1322,7 +1323,7 @@ int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p
  * that is why we also clear SIGNAL_UNKILLABLE.
  */
 static int
-force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t)
+force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t, bool sigdfl)
 {
 	unsigned long int flags;
 	int ret, blocked, ignored;
@@ -1333,7 +1334,7 @@ force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t)
 	action = &t->sighand->action[sig-1];
 	ignored = action->sa.sa_handler == SIG_IGN;
 	blocked = sigismember(&t->blocked, sig);
-	if (blocked || ignored) {
+	if (blocked || ignored || sigdfl) {
 		action->sa.sa_handler = SIG_DFL;
 		if (blocked) {
 			sigdelset(&t->blocked, sig);
@@ -1354,7 +1355,7 @@ force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t)
 
 int force_sig_info(struct kernel_siginfo *info)
 {
-	return force_sig_info_to_task(info, current);
+	return force_sig_info_to_task(info, current, false);
 }
 
 /*
@@ -1696,7 +1697,7 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr
 	info.si_flags = flags;
 	info.si_isr = isr;
 #endif
-	return force_sig_info_to_task(&info, t);
+	return force_sig_info_to_task(&info, t, false);
 }
 
 int force_sig_fault(int sig, int code, void __user *addr
@@ -1798,6 +1799,27 @@ int force_sig_perf(void __user *addr, u32 type, u64 sig_data)
 	return force_sig_info(&info);
 }
 
+/**
+ * force_sig_seccomp - signals the task to allow in-process syscall emulation
+ * @syscall: syscall number to send to userland
+ * @reason: filter-supplied reason code to send to userland (via si_errno)
+ *
+ * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
+ */
+int force_sig_seccomp(int syscall, int reason, bool force_coredump)
+{
+	struct kernel_siginfo info;
+
+	clear_siginfo(&info);
+	info.si_signo = SIGSYS;
+	info.si_code = SYS_SECCOMP;
+	info.si_call_addr = (void __user *)KSTK_EIP(current);
+	info.si_errno = reason;
+	info.si_arch = syscall_get_arch(current);
+	info.si_syscall = syscall;
+	return force_sig_info_to_task(&info, current, force_coredump);
+}
+
 /* For the crazy architectures that include trap information in
  * the errno field, instead of an actual errno value.
  */
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index 30971b1dd4a9..cb6f98f5c97a 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -416,7 +416,6 @@ COND_SYSCALL(epoll_wait);
 COND_SYSCALL(recv);
 COND_SYSCALL_COMPAT(recv);
 COND_SYSCALL(send);
-COND_SYSCALL(bdflush);
 COND_SYSCALL(uselib);
 
 /* optional: time32 */
diff --git a/tools/perf/arch/powerpc/entry/syscalls/syscall.tbl b/tools/perf/arch/powerpc/entry/syscalls/syscall.tbl
index aef2a290e71a..6f3953f2a0d5 100644
--- a/tools/perf/arch/powerpc/entry/syscalls/syscall.tbl
+++ b/tools/perf/arch/powerpc/entry/syscalls/syscall.tbl
@@ -176,7 +176,7 @@
 131	nospu	quotactl			sys_quotactl
 132	common	getpgid				sys_getpgid
 133	common	fchdir				sys_fchdir
-134	common	bdflush				sys_bdflush
+134	common	bdflush				sys_ni_syscall
 135	common	sysfs				sys_sysfs
 136	32	personality			sys_personality			ppc64_personality
 136	64	personality			ppc64_personality
diff --git a/tools/perf/arch/s390/entry/syscalls/syscall.tbl b/tools/perf/arch/s390/entry/syscalls/syscall.tbl
index 64d51ab5a8b4..8d619ec86dcc 100644
--- a/tools/perf/arch/s390/entry/syscalls/syscall.tbl
+++ b/tools/perf/arch/s390/entry/syscalls/syscall.tbl
@@ -122,7 +122,7 @@
 131  common	quotactl		sys_quotactl			sys_quotactl
 132  common	getpgid			sys_getpgid			sys_getpgid
 133  common	fchdir			sys_fchdir			sys_fchdir
-134  common	bdflush			sys_bdflush			sys_bdflush
+134  common	bdflush			-				-
 135  common	sysfs			sys_sysfs			sys_sysfs
 136  common	personality		sys_s390_personality		sys_s390_personality
 137  common	afs_syscall		-				-