From patchwork Tue Oct 1 22:59:05 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 13819067 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 760CDCF318D for ; Wed, 2 Oct 2024 00:46:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Cc:To:In-Reply-To:References :Message-Id:Content-Transfer-Encoding:Content-Type:MIME-Version:Subject:Date: From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=4dc87HmpeS9cE1L9M4FvapEXtqDd8oHbPk8aV/GQpko=; b=edYi3sf3tEnqGZy2gbR2V15Lhi S56JJGzEsofNYr+Ppg8fRy9FHG4OeG7J78a/MoVSFCvCrtTdyR2rR3fwbeEWwMdbzqbcgsQiZcCDS gly+3XrPa3jo1yrZUc4Y0MYrDPqIkUSsWOzwdJuBIQKn7JwKx7WpJ5gwMGA5VK3HatfMtffRq/kCe L8rDQdlVO7MgnN4XvhiNeR57D6f3vfWS85pXD0jPIXm41LFHl7SUDtKh8FJWzoRxbAj0pWmqMDpd5 yiu4h1rlsakq0iYJ1xwVvu8VbnoswqK2yJbv0pAvzZ5503WeoImN2z+JjvS40YzBfRCwuSXa9Z/gb 1DDqLdkA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1svnVp-00000004TXj-2se0; Wed, 02 Oct 2024 00:46:41 +0000 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1svlvQ-00000004I1i-1cer; Tue, 01 Oct 2024 23:05:00 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Cc:To:In-Reply-To:References: Message-Id:Content-Transfer-Encoding:Content-Type:MIME-Version:Subject:Date: From:Sender:Reply-To:Content-ID:Content-Description; bh=4dc87HmpeS9cE1L9M4FvapEXtqDd8oHbPk8aV/GQpko=; b=O/f72wRRVCvyy5XUdbfYI3TEho imcpUgpmtgvV6AzQDcQcEW/XaMr/h7Kseo0ui1Rcut1zKtR/Qy7ezDXZiJ3kvnzy+HpOE3YvNIA/P F0OE7yRli11lUY6uw8NBqyaRGWxwsecnGtSWUhAJ9rfeliVjKNLaBD/bb6mexQItMPXBIFItPUduO tmkQNmm0ExBAlRgRkqr6PWzRGoXSjaQIiPMcX1BshTExIuSISGlj3vhS3HIe7NAGywQY6GdkJdKiR uHpCtoBLDHCjXKSjcrVP6M9+A4xKP5kVGVOf6ygsRPFuf3TxHr7gr/cQxUZRsET+brNjsHP/v5z2t EDwHN0mw==; Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by desiato.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1svlvG-00000003KmS-3VVd; Tue, 01 Oct 2024 23:04:55 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 3F7925C0339; Tue, 1 Oct 2024 23:04:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C8BA5C4CEC6; Tue, 1 Oct 2024 23:04:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1727823889; bh=iheYVdOI1mRov1x2wnyFTq0nLuVXvcgzNFY1vvTX4L4=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=BwIW27cYksAnySxigWOYt0SrEnqSg8DQYIaOnWhOA0RmnhGPkZNsPdLvpGjXLHoFy x9mBOmkAgbznrCwLJIwQXwgbSpQgLgda83m7E8XTGR/hpwmO9+3OPAi1uU0TCEeGyM 9JiEyK/6y5TPZbGoIs2Q4X1QSD6nD+29VI2lTNHh20WKw6hGcZlOF91t4tyvyGGUud Er3KBwhnr6s/S5WpZBGIZsV6T9/+OZ8Q9UeC9TufeeP6UnCEheXFhvzHTC1pWfDdE7 blzYCs94us/bd2Nqjy+3llEwkSsm9Kk0bQaxm2WUjd4zYSbW2gZTb+pX3qgl8J3TvX ZINL9rlEvPKdg== From: Mark Brown Date: Tue, 01 Oct 2024 23:59:05 +0100 Subject: [PATCH v13 26/40] arm64/signal: Expose GCS state in signal frames MIME-Version: 1.0 Message-Id: <20241001-arm64-gcs-v13-26-222b78d87eee@kernel.org> References: <20241001-arm64-gcs-v13-0-222b78d87eee@kernel.org> In-Reply-To: <20241001-arm64-gcs-v13-0-222b78d87eee@kernel.org> To: Catalin Marinas , Will Deacon , Jonathan Corbet , Andrew Morton , Marc Zyngier , Oliver Upton , James Morse , Suzuki K Poulose , Arnd Bergmann , Oleg Nesterov , Eric Biederman , Shuah Khan , "Rick P. Edgecombe" , Deepak Gupta , Ard Biesheuvel , Szabolcs Nagy , Kees Cook Cc: "H.J. Lu" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Florian Weimer , Christian Brauner , Thiago Jung Bauermann , Ross Burton , David Spickett , Yury Khrustalev , Wilco Dijkstra , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, Mark Brown X-Mailer: b4 0.15-dev-99b12 X-Developer-Signature: v=1; a=openpgp-sha256; l=6331; i=broonie@kernel.org; h=from:subject:message-id; bh=iheYVdOI1mRov1x2wnyFTq0nLuVXvcgzNFY1vvTX4L4=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBm/H7Yz8d8MeWJ1s7RbiNfQuHzARatODnl4idncq8R cuNHIXOJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCZvx+2AAKCRAk1otyXVSH0IwMB/ 9jNDjhhihZZ4eg1B5HLLhXzEXv8N0aVlgGh/C0HpKuP1JRpb9vWvmXYmEb9b+OED6jwkbAaDTq34DO tIgwn8Hxp1xHgkhwqJPTA/ZlaSRZsLMpjQGYO50gNphK4ZTqB8UsmomfvnmqpiHRG2Tvn9yfF6ctdn 6jCSM3nAAnS9z/iZyVIRdD+DJ6uqNygJh5d+zzcrtYXSjxfHHUH6WFm4VP9CsuiY/zjMTz3cQCR+GD Dkyz+qG+3r8mAsYatUuQH1MZvCZPtuexKj1rWX0DbluY1QzNURLAZ+Wzhk6r8UfrQ2C7Dpaj+1j8fk vzEPmC/B62LJ0D69GBKu8xUJsBBlQj X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241002_000453_635815_693FD984 X-CRM114-Status: GOOD ( 22.05 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Add a context for the GCS state and include it in the signal context when running on a system that supports GCS. We reuse the same flags that the prctl() uses to specify which GCS features are enabled and also provide the current GCS pointer. We do not support enabling GCS via signal return, there is a conflict between specifying GCSPR_EL0 and allocation of a new GCS and this is not an ancticipated use case. We also enforce GCS configuration locking on signal return. Reviewed-by: Catalin Marinas Reviewed-by: Thiago Jung Bauermann Acked-by: Yury Khrustalev Signed-off-by: Mark Brown --- arch/arm64/include/uapi/asm/sigcontext.h | 9 +++ arch/arm64/kernel/signal.c | 109 +++++++++++++++++++++++++++++++ 2 files changed, 118 insertions(+) diff --git a/arch/arm64/include/uapi/asm/sigcontext.h b/arch/arm64/include/uapi/asm/sigcontext.h index bb7af77a30a7..d42f7a92238b 100644 --- a/arch/arm64/include/uapi/asm/sigcontext.h +++ b/arch/arm64/include/uapi/asm/sigcontext.h @@ -183,6 +183,15 @@ struct zt_context { __u16 __reserved[3]; }; +#define GCS_MAGIC 0x47435300 + +struct gcs_context { + struct _aarch64_ctx head; + __u64 gcspr; + __u64 features_enabled; + __u64 reserved; +}; + #endif /* !__ASSEMBLY__ */ #include diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c index b5ab0e229a78..62d666278264 100644 --- a/arch/arm64/kernel/signal.c +++ b/arch/arm64/kernel/signal.c @@ -66,6 +66,7 @@ struct rt_sigframe_user_layout { unsigned long fpsimd_offset; unsigned long esr_offset; + unsigned long gcs_offset; unsigned long sve_offset; unsigned long tpidr2_offset; unsigned long za_offset; @@ -198,6 +199,8 @@ struct user_ctxs { u32 fpmr_size; struct poe_context __user *poe; u32 poe_size; + struct gcs_context __user *gcs; + u32 gcs_size; }; static int preserve_fpsimd_context(struct fpsimd_context __user *ctx) @@ -643,6 +646,82 @@ extern int restore_zt_context(struct user_ctxs *user); #endif /* ! CONFIG_ARM64_SME */ +#ifdef CONFIG_ARM64_GCS + +static int preserve_gcs_context(struct gcs_context __user *ctx) +{ + int err = 0; + u64 gcspr = read_sysreg_s(SYS_GCSPR_EL0); + + /* + * If GCS is enabled we will add a cap token to the frame, + * include it in the GCSPR_EL0 we report to support stack + * switching via sigreturn if GCS is enabled. We do not allow + * enabling via sigreturn so the token is only relevant for + * threads with GCS enabled. + */ + if (task_gcs_el0_enabled(current)) + gcspr -= 8; + + __put_user_error(GCS_MAGIC, &ctx->head.magic, err); + __put_user_error(sizeof(*ctx), &ctx->head.size, err); + __put_user_error(gcspr, &ctx->gcspr, err); + __put_user_error(0, &ctx->reserved, err); + __put_user_error(current->thread.gcs_el0_mode, + &ctx->features_enabled, err); + + return err; +} + +static int restore_gcs_context(struct user_ctxs *user) +{ + u64 gcspr, enabled; + int err = 0; + + if (user->gcs_size != sizeof(*user->gcs)) + return -EINVAL; + + __get_user_error(gcspr, &user->gcs->gcspr, err); + __get_user_error(enabled, &user->gcs->features_enabled, err); + if (err) + return err; + + /* Don't allow unknown modes */ + if (enabled & ~PR_SHADOW_STACK_SUPPORTED_STATUS_MASK) + return -EINVAL; + + err = gcs_check_locked(current, enabled); + if (err != 0) + return err; + + /* Don't allow enabling */ + if (!task_gcs_el0_enabled(current) && + (enabled & PR_SHADOW_STACK_ENABLE)) + return -EINVAL; + + /* If we are disabling disable everything */ + if (!(enabled & PR_SHADOW_STACK_ENABLE)) + enabled = 0; + + current->thread.gcs_el0_mode = enabled; + + /* + * We let userspace set GCSPR_EL0 to anything here, we will + * validate later in gcs_restore_signal(). + */ + write_sysreg_s(gcspr, SYS_GCSPR_EL0); + + return 0; +} + +#else /* ! CONFIG_ARM64_GCS */ + +/* Turn any non-optimised out attempts to use these into a link error: */ +extern int preserve_gcs_context(void __user *ctx); +extern int restore_gcs_context(struct user_ctxs *user); + +#endif /* ! CONFIG_ARM64_GCS */ + static int parse_user_sigframe(struct user_ctxs *user, struct rt_sigframe __user *sf) { @@ -661,6 +740,7 @@ static int parse_user_sigframe(struct user_ctxs *user, user->zt = NULL; user->fpmr = NULL; user->poe = NULL; + user->gcs = NULL; if (!IS_ALIGNED((unsigned long)base, 16)) goto invalid; @@ -777,6 +857,17 @@ static int parse_user_sigframe(struct user_ctxs *user, user->fpmr_size = size; break; + case GCS_MAGIC: + if (!system_supports_gcs()) + goto invalid; + + if (user->gcs) + goto invalid; + + user->gcs = (struct gcs_context __user *)head; + user->gcs_size = size; + break; + case EXTRA_MAGIC: if (have_extra_context) goto invalid; @@ -896,6 +987,9 @@ static int restore_sigframe(struct pt_regs *regs, err = restore_fpsimd_context(&user); } + if (err == 0 && system_supports_gcs() && user.gcs) + err = restore_gcs_context(&user); + if (err == 0 && system_supports_tpidr2() && user.tpidr2) err = restore_tpidr2_context(&user); @@ -1029,6 +1123,15 @@ static int setup_sigframe_layout(struct rt_sigframe_user_layout *user, return err; } +#ifdef CONFIG_ARM64_GCS + if (system_supports_gcs() && (add_all || current->thread.gcspr_el0)) { + err = sigframe_alloc(user, &user->gcs_offset, + sizeof(struct gcs_context)); + if (err) + return err; + } +#endif + if (system_supports_sve() || system_supports_sme()) { unsigned int vq = 0; @@ -1136,6 +1239,12 @@ static int setup_sigframe(struct rt_sigframe_user_layout *user, __put_user_error(current->thread.fault_code, &esr_ctx->esr, err); } + if (system_supports_gcs() && err == 0 && user->gcs_offset) { + struct gcs_context __user *gcs_ctx = + apply_user_offset(user, user->gcs_offset); + err |= preserve_gcs_context(gcs_ctx); + } + /* Scalable Vector Extension state (including streaming), if present */ if ((system_supports_sve() || system_supports_sme()) && err == 0 && user->sve_offset) {