From nobody Fri Nov 26 14:51:19 2021 X-Original-To: dev-commits-src-main@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 6DC1518B2018; Fri, 26 Nov 2021 14:51:20 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4J0yP408tYz4qyZ; Fri, 26 Nov 2021 14:51:20 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id D3AB02658; Fri, 26 Nov 2021 14:51:19 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.16.1/8.16.1) with ESMTP id 1AQEpJ3Z040923; Fri, 26 Nov 2021 14:51:19 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.16.1/8.16.1/Submit) id 1AQEpJ7Y040922; Fri, 26 Nov 2021 14:51:19 GMT (envelope-from git) Date: Fri, 26 Nov 2021 14:51:19 GMT Message-Id: <202111261451.1AQEpJ7Y040922@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Andrew Turner Subject: git: ae92ace05fd4 - main - Per-thread stack canary on arm64 List-Id: Commit messages for the main branch of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-main List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-dev-commits-src-main@freebsd.org X-BeenThere: dev-commits-src-main@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: andrew X-Git-Repository: src X-Git-Refname: refs/heads/main X-Git-Reftype: branch X-Git-Commit: ae92ace05fd4fcf64e3bb787951578f655b1fa5f Auto-Submitted: auto-generated ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1637938280; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=twx11EOdgRM7yxrh3T6Xua/m0L8UqVwufDeirYsoqYo=; b=tgC+Nmij6Il77GcdB2gUV2JmQGFHv/qAiV0gAB1ob+6MWSsGU7tGOFeIQ6bZLDKn3v9TKs XPNO1w3kX+9FLJmUPUU2suZD0EuCGqB0HUPDZG87OfC2nnZRKARFzSFItV33D48Du4h88h P9BbYFidgtVbZzCtTRnyYfFShAAh7NySCM4VGw2uhl8BJzH0+50OyryZ8O0ApEoMSHNJPF xuQhc1UF/okVZCgcBrb1GIScJ2k1GTJ4ZMnKcBjjzl3qYtH+FxGR/ULg9Pl7XvdSuU7udo Gf5EK6jqVigPYNYK/qFrTNe8O14eP2+0ldI7qMFzZHggV24Egi0GXtcmUhNftw== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1637938280; a=rsa-sha256; cv=none; b=jJrWI3Xxsuk1gkU8yiqfyfo83ISkuH6vIDJnr5GeXldd2l50wFt5MzKh2dB4IhfHnYIHsz i/ACUpu/mC3p1x9NsyUXElJglDHQ+EQIQNBhEvIkSrW3j/oOUnTeA8LzdkycDlhO3O/8rx i1IacJDifuQqLgLCnEkZ25Ehk2R0lSZsZM/o2P9iU4WrMInrMR/dfDa32eKUh2odC8RAzs uVnbQJLaidStFUv8slK9y9E9E/ojGn3sp3Ym7owL1rWaPcCwc9F/6m0kmkbDyUtmGOkdg0 KRJMhdoEX+QQczjzG5k56JqbZl+3x4AfhAVeIYMysDDSZO8Tafo0F/UnJCFBhA== ARC-Authentication-Results: i=1; mx1.freebsd.org; none X-ThisMailContainsUnwantedMimeParts: N The branch main has been updated by andrew: URL: https://cgit.FreeBSD.org/src/commit/?id=ae92ace05fd4fcf64e3bb787951578f655b1fa5f commit ae92ace05fd4fcf64e3bb787951578f655b1fa5f Author: Andrew Turner AuthorDate: 2021-11-22 15:20:51 +0000 Commit: Andrew Turner CommitDate: 2021-11-26 14:44:00 +0000 Per-thread stack canary on arm64 With the update to llvm 13 we are able to tell the compiler it can find the SSP canary relative to the register that holds the userspace stack pointer. As this is unused in most of the kernel it can be used here to point to a per-thread SSP canary. As the kernel could be built with an old toolchain, e.g. when upgrading from 13, add a warning that the options was enabled but the compiler doesn't support it to both the build and kernel boot. Discussed with: emaste Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D33079 --- sys/arm64/arm64/exception.S | 7 +++++++ sys/arm64/arm64/genassym.c | 1 + sys/arm64/arm64/locore.S | 14 ++++++++++++++ sys/arm64/arm64/machdep.c | 22 ++++++++++++++++++++++ sys/arm64/arm64/pmap.c | 4 ++++ sys/arm64/arm64/vm_machdep.c | 10 ++++++++++ sys/arm64/conf/std.arm64 | 1 + sys/arm64/include/proc.h | 1 + sys/conf/Makefile.arm64 | 14 ++++++++++++++ sys/conf/options.arm64 | 4 ++++ 10 files changed, 78 insertions(+) diff --git a/sys/arm64/arm64/exception.S b/sys/arm64/arm64/exception.S index 22f6b7ce6145..d81bbce0efc7 100644 --- a/sys/arm64/arm64/exception.S +++ b/sys/arm64/arm64/exception.S @@ -66,6 +66,13 @@ __FBSDID("$FreeBSD$"); mrs x18, tpidr_el1 add x29, sp, #(TF_SIZE) .if \el == 0 +#if defined(PERTHREAD_SSP) + /* Load the SSP canary to sp_el0 */ + ldr x1, [x18, #(PC_CURTHREAD)] + add x1, x1, #(TD_MD_CANARY) + msr sp_el0, x1 +#endif + /* Apply the SSBD (CVE-2018-3639) workaround if needed */ ldr x1, [x18, #PC_SSBD] cbz x1, 1f diff --git a/sys/arm64/arm64/genassym.c b/sys/arm64/arm64/genassym.c index 1575a0158dec..8e3ddc48317b 100644 --- a/sys/arm64/arm64/genassym.c +++ b/sys/arm64/arm64/genassym.c @@ -73,6 +73,7 @@ ASSYM(TD_PCB, offsetof(struct thread, td_pcb)); ASSYM(TD_FLAGS, offsetof(struct thread, td_flags)); ASSYM(TD_FRAME, offsetof(struct thread, td_frame)); ASSYM(TD_LOCK, offsetof(struct thread, td_lock)); +ASSYM(TD_MD_CANARY, offsetof(struct thread, td_md.md_canary)); ASSYM(TF_SIZE, sizeof(struct trapframe)); ASSYM(TF_SP, offsetof(struct trapframe, tf_sp)); diff --git a/sys/arm64/arm64/locore.S b/sys/arm64/arm64/locore.S index 92415aab1555..bc9a7271e93a 100644 --- a/sys/arm64/arm64/locore.S +++ b/sys/arm64/arm64/locore.S @@ -116,6 +116,13 @@ virtdone: cmp x15, x14 b.lo 1b +#if defined(PERTHREAD_SSP) + /* Set sp_el0 to the boot canary for early per-thread SSP to work */ + adrp x15, boot_canary + add x15, x15, :lo12:boot_canary + msr sp_el0, x15 +#endif + /* Backup the module pointer */ mov x1, x0 @@ -200,6 +207,13 @@ mp_virtdone: ldr x4, [x4] mov sp, x4 +#if defined(PERTHREAD_SSP) + /* Set sp_el0 to the boot canary for early per-thread SSP to work */ + adrp x15, boot_canary + add x15, x15, :lo12:boot_canary + msr sp_el0, x15 +#endif + /* Load the kernel ttbr0 pagetable */ msr ttbr0_el1, x27 isb diff --git a/sys/arm64/arm64/machdep.c b/sys/arm64/arm64/machdep.c index 59a634f4d30c..821d9ba19022 100644 --- a/sys/arm64/arm64/machdep.c +++ b/sys/arm64/arm64/machdep.c @@ -109,6 +109,14 @@ enum arm64_bus arm64_bus_method = ARM64_BUS_NONE; */ struct pcpu pcpu0; +#if defined(PERTHREAD_SSP) +/* + * The boot SSP canary. Will be replaced with a per-thread canary when + * scheduling has started. + */ +uintptr_t boot_canary = 0x49a2d892bc05a0b1ul; +#endif + static struct trapframe proc0_tf; int early_boot = 1; @@ -136,6 +144,16 @@ void (*pagezero)(void *p) = pagezero_simple; int (*apei_nmi)(void); +#if defined(PERTHREAD_SSP_WARNING) +static void +print_ssp_warning(void *data __unused) +{ + printf("WARNING: Per-thread SSP is enabled but the compiler is too old to support it\n"); +} +SYSINIT(ssp_warn, SI_SUB_COPYRIGHT, SI_ORDER_ANY, print_ssp_warning, NULL); +SYSINIT(ssp_warn2, SI_SUB_LAST, SI_ORDER_ANY, print_ssp_warning, NULL); +#endif + static void pan_setup(void) { @@ -347,6 +365,9 @@ init_proc0(vm_offset_t kstack) proc_linkup0(&proc0, &thread0); thread0.td_kstack = kstack; thread0.td_kstack_pages = KSTACK_PAGES; +#if defined(PERTHREAD_SSP) + thread0.td_md.md_canary = boot_canary; +#endif thread0.td_pcb = (struct pcb *)(thread0.td_kstack + thread0.td_kstack_pages * PAGE_SIZE) - 1; thread0.td_pcb->pcb_fpflags = 0; @@ -781,6 +802,7 @@ initarm(struct arm64_bootparams *abp) "mov x18, %0 \n" "msr tpidr_el1, %0" :: "r"(pcpup)); + /* locore.S sets sp_el0 to &thread0 so no need to set it here. */ PCPU_SET(curthread, &thread0); PCPU_SET(midr, get_midr()); diff --git a/sys/arm64/arm64/pmap.c b/sys/arm64/arm64/pmap.c index cd499e026036..ef5a42c849dd 100644 --- a/sys/arm64/arm64/pmap.c +++ b/sys/arm64/arm64/pmap.c @@ -6619,6 +6619,10 @@ pmap_switch(struct thread *old __unused, struct thread *new) /* Store the new curthread */ PCPU_SET(curthread, new); +#if defined(PERTHREAD_SSP) + /* Set the new threads SSP canary */ + __asm("msr sp_el0, %0" :: "r"(&new->td_md.md_canary)); +#endif /* And the new pcb */ pcb = new->td_pcb; diff --git a/sys/arm64/arm64/vm_machdep.c b/sys/arm64/arm64/vm_machdep.c index dfc2f8cb267f..2db20427c977 100644 --- a/sys/arm64/arm64/vm_machdep.c +++ b/sys/arm64/arm64/vm_machdep.c @@ -113,6 +113,11 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags) /* Setup to release spin count in fork_exit(). */ td2->td_md.md_spinlock_count = 1; td2->td_md.md_saved_daif = PSR_DAIF_DEFAULT; + +#if defined(PERTHREAD_SSP) + /* Set the new canary */ + arc4random_buf(&td2->td_md.md_canary, sizeof(td2->td_md.md_canary)); +#endif } void @@ -187,6 +192,11 @@ cpu_copy_thread(struct thread *td, struct thread *td0) /* Setup to release spin count in fork_exit(). */ td->td_md.md_spinlock_count = 1; td->td_md.md_saved_daif = PSR_DAIF_DEFAULT; + +#if defined(PERTHREAD_SSP) + /* Set the new canary */ + arc4random_buf(&td->td_md.md_canary, sizeof(td->td_md.md_canary)); +#endif } /* diff --git a/sys/arm64/conf/std.arm64 b/sys/arm64/conf/std.arm64 index e5ed1d7db996..553e961dc0a2 100644 --- a/sys/arm64/conf/std.arm64 +++ b/sys/arm64/conf/std.arm64 @@ -67,6 +67,7 @@ options RACCT_DEFAULT_TO_DISABLED # Set kern.racct.enable=0 by default options RCTL # Resource limits options INTRNG options LINUX_BOOT_ABI # Boot using booti command from U-Boot +options PERTHREAD_SSP # Per-thread SSP canary # Debugging support. Always need this: options KDB # Enable kernel debugger support. diff --git a/sys/arm64/include/proc.h b/sys/arm64/include/proc.h index 3800798d79b7..43200fd115fc 100644 --- a/sys/arm64/include/proc.h +++ b/sys/arm64/include/proc.h @@ -37,6 +37,7 @@ struct mdthread { int md_spinlock_count; /* (k) */ register_t md_saved_daif; /* (k) */ + uintptr_t md_canary; }; struct mdproc { diff --git a/sys/conf/Makefile.arm64 b/sys/conf/Makefile.arm64 index 2e404664708c..e75062115121 100644 --- a/sys/conf/Makefile.arm64 +++ b/sys/conf/Makefile.arm64 @@ -30,6 +30,20 @@ INCLUDES+= -I$S/contrib/libfdt -I$S/contrib/device-tree/include LINUX_DTS_VERSION!= awk '/freebsd,dts-version/ { sub(/;$$/,"", $$NF); print $$NF }' $S/dts/freebsd-compatible.dts CFLAGS += -DLINUX_DTS_VERSION=\"${LINUX_DTS_VERSION}\" +PERTHREAD_SSP_ENABLED!= grep PERTHREAD_SSP opt_global.h || true ; echo +.if !empty(PERTHREAD_SSP_ENABLED) +. if ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 130000 +ARM64_SSP_CFLAGS = -mstack-protector-guard=sysreg +ARM64_SSP_CFLAGS += -mstack-protector-guard-reg=sp_el0 +ARM64_SSP_CFLAGS += -mstack-protector-guard-offset=0 +. else +ARM64_SSP_CFLAGS += -DPERTHREAD_SSP_WARNING +. warning "Compiler is too old to support PERTHREAD_SSP" +. endif +CFLAGS += ${ARM64_SSP_CFLAGS} +ARCH_FLAGS += ${ARM64_SSP_CFLAGS} +.endif + # Use a custom SYSTEM_LD command to generate the elf kernel, so we can # set the text segment start address, and also strip the "arm mapping # symbols" which have names like $a.0 and $d.2; see the document diff --git a/sys/conf/options.arm64 b/sys/conf/options.arm64 index 5185a301e55e..ff2db5caf082 100644 --- a/sys/conf/options.arm64 +++ b/sys/conf/options.arm64 @@ -8,6 +8,10 @@ VFP opt_global.h LINUX_BOOT_ABI opt_global.h LSE_ATOMICS opt_global.h +# Per-thread stack smashing protection support +# Needs clang >= 13 +PERTHREAD_SSP opt_global.h + # Binary compatibility COMPAT_FREEBSD32 opt_global.h