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(static-72-81-132-2.bltmmd.fios.verizon.net [72.81.132.2]) by mx.zohomail.com with SMTPS id 165090736101574.01795310864475; Mon, 25 Apr 2022 10:22:41 -0700 (PDT) X-Outflank-Mailman: Message body and most headers restored to incoming version X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 547a57f6-c4bc-11ec-8fc2-03012f2f19d4 ARC-Seal: i=1; a=rsa-sha256; t=1650907364; cv=none; d=zohomail.com; s=zohoarc; b=Ax7o3r8U6B4PFgzUw5bx5r5LBu41GigSNecUltuuR8dSVKqxbPPtGcByzXoFgDjdADU7QKgB1uZXGmjVUff6lm7NXHWOL9n0sjS2mM6pb823DSF7vTfb/O6zGQ3rz6uISOYXYcmKI4ggGXkHITATaLgqXss6mHvF93u3Bx3ELOs= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1650907364; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:To; bh=oWUECp0uPTpkjJDOsexyWnv+2pg/Sqhs5LeSRzZUWDE=; b=EUv11YhBQ0tOe10FRarzQEXENGkwHC6k4Hr+uvouLRTLMaVYAkzXXB5pKl+j07RfbEsFStv0pjQrAd5dxtEFgOpnM9OpFMMME3uPG1+F5mUxjtfmCY7scXme17aR6qDkoH8MUMJbMjKKiBG9K0liFnWhZ8xtszbRJr2Bcwt0PjE= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=apertussolutions.com; spf=pass smtp.mailfrom=dpsmith@apertussolutions.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1650907364; s=zoho; d=apertussolutions.com; i=dpsmith@apertussolutions.com; h=From:From:To:To:Cc:Cc:Subject:Subject:Date:Date:Message-Id:Message-Id:In-Reply-To:References:MIME-Version:Content-Transfer-Encoding:Reply-To; bh=oWUECp0uPTpkjJDOsexyWnv+2pg/Sqhs5LeSRzZUWDE=; b=q7+Vq5H27jfV2rMgnQ1pGolKGQKsX1cUXzzyM5cwDvejg7q1HW84xnh2x5VncO3K aPXYPMuv0zooJEuuyopcldSPizgpKZwRFLqYo+36n1w1rP8417RHaWnQtO+czrWk7zF KOe2jjbkIOJRJjiSNjyRZAgZYkpevehOAOBPc3qE= From: "Daniel P. Smith" To: xen-devel@lists.xenproject.org, Volodymyr Babchuk , Wei Liu , "Daniel P. Smith" Cc: scott.davis@starlab.io, jandryuk@gmail.com, Stefano Stabellini , Julien Grall , Bertrand Marquis , Jan Beulich , Andrew Cooper , =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= , George Dunlap , Dario Faggioli , Daniel De Graaf Subject: [PATCH v4 1/2] xsm: create idle domain privileged and demote after setup Date: Mon, 25 Apr 2022 13:22:30 -0400 Message-Id: <20220425172231.27401-2-dpsmith@apertussolutions.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20220425172231.27401-1-dpsmith@apertussolutions.com> References: <20220425172231.27401-1-dpsmith@apertussolutions.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ZohoMailClient: External X-ZohoMail-DKIM: pass (identity dpsmith@apertussolutions.com) X-ZM-MESSAGEID: 1650907400167100001 Content-Type: text/plain; charset="utf-8" There are new capabilities, dom0less and hyperlaunch, that introduce intern= al hypervisor logic which needs to make resource allocation calls that are protected by XSM access checks. This creates an issue as a subset of the hypervisor code is executed under a system domain, the idle domain, that is represented by a per-CPU non-privileged struct domain. To enable these new capabilities to function correctly but in a controlled manner, this commit changes the idle system domain to be created as a privileged domain under t= he default policy and demoted before transitioning to running. A new XSM hook, xsm_set_system_active(), is introduced to allow each XSM policy type to dem= ote the idle domain appropriately for that policy type. In the case of SILO, it inherits the default policy's hook for xsm_set_system_active(). For flask a stub is added to ensure that flask policy system will function correctly with this patch until flask is extended with support for starting= the idle domain privileged and properly demoting it on the call to xsm_set_system_active(). Signed-off-by: Daniel P. Smith Reviewed-by: Jason Andryuk --- xen/arch/arm/setup.c | 3 +++ xen/arch/x86/setup.c | 3 +++ xen/common/sched/core.c | 7 ++++++- xen/include/xsm/dummy.h | 17 +++++++++++++++++ xen/include/xsm/xsm.h | 6 ++++++ xen/xsm/dummy.c | 1 + xen/xsm/flask/hooks.c | 21 +++++++++++++++++++++ 7 files changed, 57 insertions(+), 1 deletion(-) diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c index d5d0792ed4..dc0bdef6b7 100644 --- a/xen/arch/arm/setup.c +++ b/xen/arch/arm/setup.c @@ -1048,6 +1048,9 @@ void __init start_xen(unsigned long boot_phys_offset, /* Hide UART from DOM0 if we're using it */ serial_endboot(); =20 + if ( xsm_set_system_active() !=3D 0 ) + panic("xsm: unable to set hypervisor to SYSTEM_ACTIVE privilege\n"= ); + system_state =3D SYS_STATE_active; =20 for_each_domain( d ) diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c index 6f20e17892..e7a0ac9183 100644 --- a/xen/arch/x86/setup.c +++ b/xen/arch/x86/setup.c @@ -621,6 +621,9 @@ static void noreturn init_done(void) void *va; unsigned long start, end; =20 + if ( xsm_set_system_active() !=3D 0 ) + panic("xsm: unable to set hypervisor to SYSTEM_ACTIVE privilege\n"= ); + system_state =3D SYS_STATE_active; =20 domain_unpause_by_systemcontroller(dom0); diff --git a/xen/common/sched/core.c b/xen/common/sched/core.c index 19ab678181..7b1c03a0e1 100644 --- a/xen/common/sched/core.c +++ b/xen/common/sched/core.c @@ -3021,7 +3021,12 @@ void __init scheduler_init(void) sched_ratelimit_us =3D SCHED_DEFAULT_RATELIMIT_US; } =20 - idle_domain =3D domain_create(DOMID_IDLE, NULL, 0); + /* + * The idle dom is created privileged to ensure unrestricted access du= ring + * setup and will be demoted by xsm_set_system_active() when setup is + * complete. + */ + idle_domain =3D domain_create(DOMID_IDLE, NULL, CDF_privileged); BUG_ON(IS_ERR(idle_domain)); BUG_ON(nr_cpu_ids > ARRAY_SIZE(idle_vcpu)); idle_domain->vcpu =3D idle_vcpu; diff --git a/xen/include/xsm/dummy.h b/xen/include/xsm/dummy.h index 58afc1d589..3291fb5396 100644 --- a/xen/include/xsm/dummy.h +++ b/xen/include/xsm/dummy.h @@ -101,6 +101,23 @@ static always_inline int xsm_default_action( } } =20 +static XSM_INLINE int cf_check xsm_set_system_active(void) +{ + struct domain *d =3D current->domain; + + ASSERT(d->is_privileged); + + if ( d->domain_id !=3D DOMID_IDLE ) + { + printk("xsm_set_system_active: should only be called by idle domai= n\n"); + return -EPERM; + } + + d->is_privileged =3D false; + + return 0; +} + static XSM_INLINE void cf_check xsm_security_domaininfo( struct domain *d, struct xen_domctl_getdomaininfo *info) { diff --git a/xen/include/xsm/xsm.h b/xen/include/xsm/xsm.h index 3e2b7fe3db..8dad03fd3d 100644 --- a/xen/include/xsm/xsm.h +++ b/xen/include/xsm/xsm.h @@ -52,6 +52,7 @@ typedef enum xsm_default xsm_default_t; * !!! WARNING !!! */ struct xsm_ops { + int (*set_system_active)(void); void (*security_domaininfo)(struct domain *d, struct xen_domctl_getdomaininfo *info); int (*domain_create)(struct domain *d, uint32_t ssidref); @@ -208,6 +209,11 @@ extern struct xsm_ops xsm_ops; =20 #ifndef XSM_NO_WRAPPERS =20 +static inline int xsm_set_system_active(void) +{ + return alternative_call(xsm_ops.set_system_active); +} + static inline void xsm_security_domaininfo( struct domain *d, struct xen_domctl_getdomaininfo *info) { diff --git a/xen/xsm/dummy.c b/xen/xsm/dummy.c index 8c044ef615..e6ffa948f7 100644 --- a/xen/xsm/dummy.c +++ b/xen/xsm/dummy.c @@ -14,6 +14,7 @@ #include =20 static const struct xsm_ops __initconst_cf_clobber dummy_ops =3D { + .set_system_active =3D xsm_set_system_active, .security_domaininfo =3D xsm_security_domaininfo, .domain_create =3D xsm_domain_create, .getdomaininfo =3D xsm_getdomaininfo, diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c index 0bf63ffa84..8a62de2fd6 100644 --- a/xen/xsm/flask/hooks.c +++ b/xen/xsm/flask/hooks.c @@ -186,6 +186,26 @@ static int cf_check flask_domain_alloc_security(struct= domain *d) return 0; } =20 +static int cf_check flask_set_system_active(void) +{ + struct domain *d =3D current->domain; + + if ( d->domain_id !=3D DOMID_IDLE ) + { + printk("xsm_set_system_active should only be called by idle domain= \n"); + return -EPERM; + } + + /* + * While is_privileged has no significant meaning under flask, set to = false + * as there are times in hypervisor code privilege checks check this + * directly instead of going through XSM. + */ + d->is_privileged =3D false; + + return 0; +} + static void cf_check flask_domain_free_security(struct domain *d) { struct domain_security_struct *dsec =3D d->ssid; @@ -1766,6 +1786,7 @@ static int cf_check flask_argo_send( #endif =20 static const struct xsm_ops __initconst_cf_clobber flask_ops =3D { + .set_system_active =3D flask_set_system_active, .security_domaininfo =3D flask_security_domaininfo, .domain_create =3D flask_domain_create, .getdomaininfo =3D flask_getdomaininfo, --=20 2.20.1