From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4B22AC433FE for ; Tue, 22 Nov 2022 10:11:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=F1Sy3dXVydh6odnGLgWHWgFtXyh3+3bRKGM89jXFOw4=; b=gQ3dZa+t9+8D58 +mfHtOHTCYc3b93VxqjQSaZucyfesfWYREcKPfNkdrAgc73hIML21ho5kcUiSFeM10IrwMT7yLO4F +GER70yGtpOlYPRLozldIHKNgfnlcFXeqUCGwzj6bIggdzFOjZzRNrTIN+nfpiri0FvoGTE5JjCYK puz3PY9k6sNnyhqyDHZA16WD2bYbuNGfHGgmSnLKVBB/lQ2kW+gpULChtF49lIDesVEEtt8IUehDj GQzIixD3n10KAYkRXkPw19qn5quu81j4ReI+9cpQwmIUyHr58pshps29w+D3YcST2cvJ2y3NtaIW7 u2Nn5Z+RfrK+Ec+aArFg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oxQFV-007gAh-NN; Tue, 22 Nov 2022 10:11:29 +0000 Received: from s3.sipsolutions.net ([2a01:4f8:191:4433::2] helo=sipsolutions.net) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oxQF3-007fef-1Q for linux-um@lists.infradead.org; Tue, 22 Nov 2022 10:11:12 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sipsolutions.net; s=mail; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Content-Type:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-To: Resent-Cc:Resent-Message-ID; bh=wBUw3g+BEgREJ50tuzbsm0z1YB8OYVuRBcANh0RJiVs=; t=1669111860; x=1670321460; b=TAi5iXb63LkTUUeLg8rxP5f2ojHEtynpstA2ps9z7fr0W10 mbyMzPCCcG8DdrwwgWQ1q9xxZmEI1HowU4R3BiDRBxxuCixUVZwe4f4SRjOtqMYQW2McFEVcE2+iS 9jyfRqzo2ACDvwGuVNY6WlnhFFrII3ZX+CVpxWP0/apMI1nBpemIseW3QyhWOaJYvbhIlBn8na11h pxdLGJEZLu2XBdsUR05nIAvKLpYNSx9xd9/ry8yBzMs0SDyib9UtjCYTl2FYDjraf/hqrlVTGa5hC dHw2ZVM3qAREJPOgCrPp1cOWzpnEr/0ak5JZIHC7HRPNSUGlWqf0uG5dbPn0zwUA==; Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.96) (envelope-from ) id 1oxQEt-006IGn-1y; Tue, 22 Nov 2022 11:10:51 +0100 From: benjamin@sipsolutions.net To: linux-um@lists.infradead.org Cc: Benjamin Berg , Johannes Berg Subject: [PATCH v2 23/28] um: Add stub side of SECCOMP/futex based process handling Date: Tue, 22 Nov 2022 11:07:54 +0100 Message-Id: <20221122100759.208290-24-benjamin@sipsolutions.net> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221122100759.208290-1-benjamin@sipsolutions.net> References: <20221122100759.208290-1-benjamin@sipsolutions.net> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221122_021101_393511_3C494A88 X-CRM114-Status: GOOD ( 21.63 ) X-BeenThere: linux-um@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-um" Errors-To: linux-um-bounces+linux-um=archiver.kernel.org@lists.infradead.org From: Benjamin Berg This adds the stub side for the new seccomp process management code. In this case we do register save/restore through the signal handler mcontext. For the FS_BASE/GS_BASE register we need special handling. Co-authored-by: Johannes Berg Signed-off-by: Benjamin Berg --- arch/um/include/shared/skas/stub-data.h | 15 +++++++ arch/um/kernel/skas/clone.c | 24 +++++++++++ arch/um/kernel/skas/stub.c | 54 +++++++++++++++++++++++++ arch/x86/um/shared/sysdep/stub-data.h | 12 ++++++ arch/x86/um/shared/sysdep/stub.h | 3 ++ arch/x86/um/shared/sysdep/stub_32.h | 7 ++++ arch/x86/um/shared/sysdep/stub_64.h | 14 +++++++ 7 files changed, 129 insertions(+) create mode 100644 arch/x86/um/shared/sysdep/stub-data.h diff --git a/arch/um/include/shared/skas/stub-data.h b/arch/um/include/shared/skas/stub-data.h index 821c1e98c051..6a6bc34f70c4 100644 --- a/arch/um/include/shared/skas/stub-data.h +++ b/arch/um/include/shared/skas/stub-data.h @@ -8,8 +8,13 @@ #ifndef __STUB_DATA_H #define __STUB_DATA_H +#include #include #include +#include + +#define FUTEX_IN_CHILD 0 +#define FUTEX_IN_KERN 1 #define STUB_NEXT_SYSCALL(s) \ ((struct stub_syscall *) (((unsigned long) s) + (s)->cmd_len)) @@ -31,6 +36,16 @@ struct stub_data { /* 128 leaves enough room for additional fields in the struct */ unsigned char syscall_data[UM_KERN_PAGE_SIZE - 128] __aligned(16); + /* data shared with signal handler (only used in seccomp mode) */ + short restart_wait; + unsigned int futex; + int signal; + unsigned short si_offset; + unsigned short mctx_offset; + + /* seccomp architecture specific state restore */ + struct stub_data_arch arch_data; + /* Stack for our signal handlers and for calling into . */ unsigned char sigstack[UM_KERN_PAGE_SIZE] __aligned(UM_KERN_PAGE_SIZE); }; diff --git a/arch/um/kernel/skas/clone.c b/arch/um/kernel/skas/clone.c index 8b6ea9c00133..97728b7dd54d 100644 --- a/arch/um/kernel/skas/clone.c +++ b/arch/um/kernel/skas/clone.c @@ -48,3 +48,27 @@ stub_clone_handler(void) done: trap_myself(); } + +#ifdef CONFIG_UML_SECCOMP +void __attribute__ ((__section__ (".__syscall_stub"))) +stub_clone_handler_seccomp(void) +{ + struct stub_data *data = get_stub_page() + UM_KERN_PAGE_SIZE; + long err; + + /* Use the syscall data as a temporary stack area (bottom half for clone). */ + err = stub_syscall2(__NR_clone, CLONE_PARENT | CLONE_FILES | SIGCHLD, + (unsigned long) data->syscall_data + + sizeof(data->syscall_data) / 2 - + sizeof(void *)); + if (err) { + data->err = err; + goto done; + } + + remap_stack_and_trap(); + + done: + trap_myself(); +} +#endif diff --git a/arch/um/kernel/skas/stub.c b/arch/um/kernel/skas/stub.c index 0a13f5d21d08..4bb90395a12b 100644 --- a/arch/um/kernel/skas/stub.c +++ b/arch/um/kernel/skas/stub.c @@ -5,6 +5,11 @@ #include +#ifdef CONFIG_UML_SECCOMP +#include +#include +#endif + static __always_inline int syscall_handler(struct stub_data *d) { struct stub_syscall *sc; @@ -45,3 +50,52 @@ stub_syscall_handler(void) trap_myself(); } + +#ifdef CONFIG_UML_SECCOMP +void __attribute__ ((__section__ (".__syscall_stub"))) +stub_signal_interrupt(int sig, siginfo_t *info, void *p) +{ + struct stub_data *d = get_stub_page(); + ucontext_t *uc = p; + long res; + + d->signal = sig; + d->si_offset = (unsigned long)info - (unsigned long)&d->sigstack[0]; + d->mctx_offset = (unsigned long)&uc->uc_mcontext - (unsigned long)&d->sigstack[0]; + +restart_wait: + d->futex = FUTEX_IN_KERN; + do { + res = stub_syscall3(__NR_futex, (unsigned long)&d->futex, + FUTEX_WAKE, 1); + } while (res == -EINTR); + do { + res = stub_syscall4(__NR_futex, (unsigned long)&d->futex, + FUTEX_WAIT, FUTEX_IN_KERN, 0); + } while (res == -EINTR || d->futex == FUTEX_IN_KERN); + + if (res < 0 && res != -EAGAIN) + stub_syscall2(__NR_kill, 0, SIGKILL); + + /* Try running queued syscalls. */ + if (syscall_handler(d) < 0 || d->restart_wait) { + /* Report SIGTRAP if we restart. */ + d->signal = SIGTRAP; + d->restart_wait = 0; + goto restart_wait; + } + + /* Return so that the host modified mcontext is restored. */ +} + +void __attribute__ ((__section__ (".__syscall_stub"))) +stub_signal_restorer(void) +{ + struct stub_data *d = get_stub_page(); + + /* Restore arch dependent state that is not part of the mcontext */ + stub_seccomp_restore_state(&d->arch_data); + + stub_syscall0(__NR_rt_sigreturn); +} +#endif diff --git a/arch/x86/um/shared/sysdep/stub-data.h b/arch/x86/um/shared/sysdep/stub-data.h new file mode 100644 index 000000000000..b0b6f2a95f0e --- /dev/null +++ b/arch/x86/um/shared/sysdep/stub-data.h @@ -0,0 +1,12 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifdef __i386__ +struct stub_data_arch { }; +#else +#define STUB_SYNC_FS_BASE (1 << 0) +#define STUB_SYNC_GS_BASE (1 << 1) +struct stub_data_arch { + int sync; + unsigned long fs_base; + unsigned long gs_base; +}; +#endif diff --git a/arch/x86/um/shared/sysdep/stub.h b/arch/x86/um/shared/sysdep/stub.h index 579681d12158..eb2e3a24d40b 100644 --- a/arch/x86/um/shared/sysdep/stub.h +++ b/arch/x86/um/shared/sysdep/stub.h @@ -14,3 +14,6 @@ extern void stub_segv_handler(int, siginfo_t *, void *); extern void stub_syscall_handler(void); extern void stub_clone_handler(void); +extern void stub_signal_interrupt(int, siginfo_t *, void *); +extern void stub_signal_restorer(void); +extern void stub_clone_handler_seccomp(void); diff --git a/arch/x86/um/shared/sysdep/stub_32.h b/arch/x86/um/shared/sysdep/stub_32.h index 9531e52b0a3e..c8328a1949ee 100644 --- a/arch/x86/um/shared/sysdep/stub_32.h +++ b/arch/x86/um/shared/sysdep/stub_32.h @@ -144,4 +144,11 @@ static __always_inline void *get_stub_page(void) return (void *)ret; } + +static __always_inline void +stub_seccomp_restore_state(struct stub_data_arch *arch) +{ + /* No extra arch specific restore */ +} + #endif diff --git a/arch/x86/um/shared/sysdep/stub_64.h b/arch/x86/um/shared/sysdep/stub_64.h index bd2f62530bcc..99c5e54654a7 100644 --- a/arch/x86/um/shared/sysdep/stub_64.h +++ b/arch/x86/um/shared/sysdep/stub_64.h @@ -10,6 +10,7 @@ #include #include #include +#include #define STUB_MMAP_NR __NR_mmap #define MMAP_OFFSET(o) (o) @@ -140,4 +141,17 @@ static __always_inline void *get_stub_page(void) return (void *)ret - UM_KERN_PAGE_SIZE; } + +static __always_inline void +stub_seccomp_restore_state(struct stub_data_arch *arch) +{ + /* TODO: Use _writefsbase_u64/_writegsbase_u64 when possible */ + if (arch->sync & STUB_SYNC_FS_BASE) + stub_syscall2(__NR_arch_prctl, ARCH_SET_FS, arch->fs_base); + if (arch->sync & STUB_SYNC_GS_BASE) + stub_syscall2(__NR_arch_prctl, ARCH_SET_GS, arch->gs_base); + + arch->sync = 0; +} + #endif -- 2.38.1 _______________________________________________ linux-um mailing list linux-um@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-um