From b48c7236b13cb5ef1b5fdf744aa8841df0f7b43a Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Tue, 29 Jun 2021 15:11:44 -0500 Subject: exit/bdflush: Remove the deprecated bdflush system call The bdflush system call has been deprecated for a very long time. Recently Michael Schmitz tested[1] and found that the last known caller of of the bdflush system call is unaffected by it's removal. Since the code is not needed delete it. [1] https://lkml.kernel.org/r/36123b5d-daa0-6c2b-f2d4-a942f069fd54@gmail.com Link: https://lkml.kernel.org/r/87sg10quue.fsf_-_@disp2133 Tested-by: Michael Schmitz Acked-by: Geert Uytterhoeven Reviewed-by: Arnd Bergmann Acked-by: Cyril Hrubis Signed-off-by: "Eric W. Biederman" --- kernel/sys_ni.c | 1 - 1 file changed, 1 deletion(-) (limited to 'kernel') 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 */ -- cgit From 307d522f5eb86cd6ac8c905f5b0577dedac54ec5 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Wed, 23 Jun 2021 16:44:32 -0500 Subject: signal/seccomp: Refactor seccomp signal and coredump generation Factor out force_sig_seccomp from the seccomp signal generation and place it in kernel/signal.c. The function force_sig_seccomp takes a parameter force_coredump to indicate that the sigaction field should be reset to SIGDFL so that a coredump will be generated when the signal is delivered. force_sig_seccomp is then used to replace both seccomp_send_sigsys and seccomp_init_siginfo. force_sig_info_to_task gains an extra parameter to force using the default signal action. With this change seccomp is no longer a special case and there becomes exactly one place do_coredump is called from. Further it no longer becomes necessary for __seccomp_filter to call do_group_exit. Acked-by: Kees Cook Link: https://lkml.kernel.org/r/87r1gr6qc4.fsf_-_@disp2133 Signed-off-by: "Eric W. Biederman" --- kernel/seccomp.c | 40 ++++++---------------------------------- kernel/signal.c | 30 ++++++++++++++++++++++++++---- 2 files changed, 32 insertions(+), 38 deletions(-) (limited to 'kernel') diff --git a/kernel/seccomp.c b/kernel/seccomp.c index 057e17f3215d..abcbd3d2ba54 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: @@ -1289,18 +1265,14 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd, /* 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; - /* 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 a3229add4455..fbf941b80dd4 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -54,6 +54,7 @@ #include #include #include +#include /* 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); } /* @@ -1685,7 +1686,7 @@ 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 @@ -1793,6 +1794,27 @@ 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. */ -- cgit From d21918e5a94a862ccb297b9f2be38574c865fda0 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Wed, 23 Jun 2021 16:51:49 -0500 Subject: signal/seccomp: Dump core when there is only one live thread Replace get_nr_threads with atomic_read(¤t->signal->live) as that is a more accurate number that is decremented sooner. Acked-by: Kees Cook Link: https://lkml.kernel.org/r/87lf6z6qbd.fsf_-_@disp2133 Signed-off-by: "Eric W. Biederman" --- kernel/seccomp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/seccomp.c b/kernel/seccomp.c index abcbd3d2ba54..afa4db097068 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -1264,7 +1264,7 @@ 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) { + (atomic_read(¤t->signal->live) == 1)) { /* Show the original registers in the dump. */ syscall_rollback(current, current_pt_regs()); /* Trigger a coredump with SIGSYS */ -- cgit