From patchwork Thu Aug 1 12:06:51 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 13750334 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 431EE1A4B2C; Thu, 1 Aug 2024 13:00:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722517204; cv=none; b=mnkq9o+JjKNfhlAkszsOKoX2FXzkPgUcjkS8GynTyQyPmHjEqRIN6bAso1KvHOeVrXlNBHuNZ85q/kPvMuLFR5oXANOt/+66UCGNAvxw9ZdXr0IFY9BoKVyg1BqOOUe/piY5AoOirjTe7ghD4ehYQEH3+t4o1QbOdq/fOlbhowQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722517204; c=relaxed/simple; bh=kpYoeEKXM/IVjTgCGNGqe131qZl9kDt0bNYWPvrqBbk=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=XJT1e5RQrZdVUEFAxKbz8aP0zgVAQK63s1e8TrQtHe5ZP51ESmAy9zW46lbWUo2x+6qTOO2UEc4augcBKEtOST13bl46F/3Vlh/2N3W68SZH56GNveboiZ5UYIvm8OZ/ZfSYMgVtFHKhf0YGn8FQtYQWzpKa1eezxjndsdOEnPw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HpYaP2MI; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="HpYaP2MI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 75C8FC32786; Thu, 1 Aug 2024 12:59:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1722517203; bh=kpYoeEKXM/IVjTgCGNGqe131qZl9kDt0bNYWPvrqBbk=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=HpYaP2MI+mP0WS66w50alD68EsWa5FHYkuAoNe7krHyq4k2kWBVMBZP0yX0DsQjaG 9FknGSb9amgoKDpkG9qxU5PlFfePzuIRrG2/bwq4mWOFuumIzaNY70UR9EUltyaFC9 qbXFWafbtC9r1lSGZxjIDbLeF2871t8Yj77zb/C4fNlwX80r48OMWqXNDJisAzHE0L Yh6QD+b+WYJ02pRTKHYZxCUP0IosMaq8rpxVPoo/MJw3JiKPx+2V2PpDePUaZ5le/0 +qCC/c1Ge5pVpzCsODOURH+DK/Yqa/JBL2fPuPhMwSboa5khQAudsc6gDHo3YammpU Z5Jts9QA2f4Fg== From: Mark Brown Date: Thu, 01 Aug 2024 13:06:51 +0100 Subject: [PATCH v10 24/40] arm64/signal: Expose GCS state in signal frames Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20240801-arm64-gcs-v10-24-699e2bd2190b@kernel.org> References: <20240801-arm64-gcs-v10-0-699e2bd2190b@kernel.org> In-Reply-To: <20240801-arm64-gcs-v10-0-699e2bd2190b@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 , 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-37811 X-Developer-Signature: v=1; a=openpgp-sha256; l=6063; i=broonie@kernel.org; h=from:subject:message-id; bh=kpYoeEKXM/IVjTgCGNGqe131qZl9kDt0bNYWPvrqBbk=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBmq4YYxABEbOuonpSgRJMOS5HfKbwvlkvC8WJQtg89 D4P8dNWJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCZquGGAAKCRAk1otyXVSH0HkaCA CAk+bQRSEGsLGc+biG2RDA3oWgUHaFwyKIU14RadwVXvjgocjWKvZb/Wp99dluj/hVUKcbfe+VZhND SM4eRNao2rOTfdCR2v6KW3n8s4sSrmPwYwdq45PhzCUVnNbkpJ5Cxbe2GzfIjcP3O8QnXeR+j1djjr 2xfeTgQbTg+ehHo4j6F0u2nPFs7POZQVKZ8GiES0XRpRFl5oKgPZXj4ORR34/6XIN+8mpEhcOffuXv LBNUsUuyoj1aY9IhwTGPE1Iy8KaLPu8F/lsm+InhK8c25MvyKwZqoMsEJRO0zsjCXFNKQVVuBuS/bY KWFKXGUNqIYelhSio94GVc2LBWDxZ8 X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB 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: Thiago Jung Bauermann Signed-off-by: Mark Brown --- arch/arm64/include/uapi/asm/sigcontext.h | 9 +++ arch/arm64/kernel/signal.c | 106 +++++++++++++++++++++++++++++++ 2 files changed, 115 insertions(+) diff --git a/arch/arm64/include/uapi/asm/sigcontext.h b/arch/arm64/include/uapi/asm/sigcontext.h index 8a45b7a411e0..c2d61e8efc84 100644 --- a/arch/arm64/include/uapi/asm/sigcontext.h +++ b/arch/arm64/include/uapi/asm/sigcontext.h @@ -176,6 +176,15 @@ 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 a1e0aa38bff9..6db364beb024 100644 --- a/arch/arm64/kernel/signal.c +++ b/arch/arm64/kernel/signal.c @@ -88,6 +88,7 @@ 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; @@ -217,6 +218,8 @@ struct user_ctxs { u32 zt_size; struct fpmr_context __user *fpmr; u32 fpmr_size; + struct gcs_context __user *gcs; + u32 gcs_size; }; static int preserve_fpsimd_context(struct fpsimd_context __user *ctx) @@ -636,6 +639,81 @@ 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; + + /* + * We will add a cap token to the frame, include it in the + * GCSPR_EL0 we report to support stack switching via + * sigreturn. + */ + gcs_preserve_current_state(); + gcspr = current->thread.gcspr_el0 - 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(). + */ + current->thread.gcspr_el0 = gcspr; + write_sysreg_s(current->thread.gcspr_el0, 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) { @@ -653,6 +731,7 @@ static int parse_user_sigframe(struct user_ctxs *user, user->za = NULL; user->zt = NULL; user->fpmr = NULL; + user->gcs = NULL; if (!IS_ALIGNED((unsigned long)base, 16)) goto invalid; @@ -758,6 +837,17 @@ 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; @@ -877,6 +967,9 @@ 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); @@ -999,6 +1092,13 @@ static int setup_sigframe_layout(struct rt_sigframe_user_layout *user, return err; } + if (add_all || task_gcs_el0_enabled(current)) { + err = sigframe_alloc(user, &user->gcs_offset, + sizeof(struct gcs_context)); + if (err) + return err; + } + if (system_supports_sve() || system_supports_sme()) { unsigned int vq = 0; @@ -1099,6 +1199,12 @@ 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) {