Date: Mon, 16 Feb 2026 15:29:11 +0000 From: Mark Johnston <markj@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: c71354030a26 - main - vmm: Allow the use of PCI passthrough in a jail Message-ID: <699337c7.1dcc8.3cb007a8@gitrepo.freebsd.org>
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The branch main has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=c71354030a26900e564f0c80a8abdff7e77b3c9e commit c71354030a26900e564f0c80a8abdff7e77b3c9e Author: Mark Johnston <markj@FreeBSD.org> AuthorDate: 2026-02-16 14:56:25 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2026-02-16 15:28:49 +0000 vmm: Allow the use of PCI passthrough in a jail After commit e11768e94787 ("vmm: Add PRIV_DRIVER checks for passthru ioctls"), it is not possible to use PCI passthru from jails, as PRIV_DRIVER is not granted to jails. Apparently some users expect this to work, understanding that jailing bhyve provides little security benefit in this configuration. I believe we should disable ppt access in jails even when allow.vmm is configured. To provide an escape hatch for users, add a new allow.vmm_ppt jail configuration knob, and check it when handling ppt ioctls in jails. Also add a new PRIV_VMM_PPTDEV to replace the use of PRIV_DRIVER. PR: 292750 Reviewed by: corvink MFC after: 2 weeks Sponsored by: The FreeBSD Foundation Sponsored by: Klara, Inc. Differential Revision: https://reviews.freebsd.org/D55066 --- sys/amd64/vmm/vmm_dev_machdep.c | 14 +++++++------- sys/dev/vmm/vmm_dev.c | 20 +++++++++++++------- sys/dev/vmm/vmm_dev.h | 2 +- sys/kern/kern_jail.c | 7 +++++++ sys/sys/priv.h | 7 ++++++- usr.sbin/jail/jail.8 | 11 +++++++++++ 6 files changed, 45 insertions(+), 16 deletions(-) diff --git a/sys/amd64/vmm/vmm_dev_machdep.c b/sys/amd64/vmm/vmm_dev_machdep.c index b84be809ea24..55fccf8f25b2 100644 --- a/sys/amd64/vmm/vmm_dev_machdep.c +++ b/sys/amd64/vmm/vmm_dev_machdep.c @@ -125,15 +125,15 @@ const struct vmmdev_ioctl vmmdev_machdep_ioctls[] = { VMMDEV_IOCTL(VM_BIND_PPTDEV, VMMDEV_IOCTL_XLOCK_MEMSEGS | VMMDEV_IOCTL_LOCK_ALL_VCPUS | - VMMDEV_IOCTL_PRIV_CHECK_DRIVER), + VMMDEV_IOCTL_PPT), VMMDEV_IOCTL(VM_UNBIND_PPTDEV, VMMDEV_IOCTL_XLOCK_MEMSEGS | VMMDEV_IOCTL_LOCK_ALL_VCPUS | - VMMDEV_IOCTL_PRIV_CHECK_DRIVER), + VMMDEV_IOCTL_PPT), VMMDEV_IOCTL(VM_MAP_PPTDEV_MMIO, VMMDEV_IOCTL_LOCK_ALL_VCPUS | - VMMDEV_IOCTL_PRIV_CHECK_DRIVER), + VMMDEV_IOCTL_PPT), VMMDEV_IOCTL(VM_UNMAP_PPTDEV_MMIO, VMMDEV_IOCTL_LOCK_ALL_VCPUS | - VMMDEV_IOCTL_PRIV_CHECK_DRIVER), + VMMDEV_IOCTL_PPT), #ifdef BHYVE_SNAPSHOT #ifdef COMPAT_FREEBSD13 VMMDEV_IOCTL(VM_SNAPSHOT_REQ_13, VMMDEV_IOCTL_LOCK_ALL_VCPUS), @@ -151,9 +151,9 @@ const struct vmmdev_ioctl vmmdev_machdep_ioctls[] = { VMMDEV_IOCTL(VM_LAPIC_LOCAL_IRQ, VMMDEV_IOCTL_MAYBE_ALLOC_VCPU), - VMMDEV_IOCTL(VM_PPTDEV_MSI, VMMDEV_IOCTL_PRIV_CHECK_DRIVER), - VMMDEV_IOCTL(VM_PPTDEV_MSIX, VMMDEV_IOCTL_PRIV_CHECK_DRIVER), - VMMDEV_IOCTL(VM_PPTDEV_DISABLE_MSIX, VMMDEV_IOCTL_PRIV_CHECK_DRIVER), + VMMDEV_IOCTL(VM_PPTDEV_MSI, VMMDEV_IOCTL_PPT), + VMMDEV_IOCTL(VM_PPTDEV_MSIX, VMMDEV_IOCTL_PPT), + VMMDEV_IOCTL(VM_PPTDEV_DISABLE_MSIX, VMMDEV_IOCTL_PPT), VMMDEV_IOCTL(VM_LAPIC_MSI, 0), VMMDEV_IOCTL(VM_IOAPIC_ASSERT_IRQ, 0), VMMDEV_IOCTL(VM_IOAPIC_DEASSERT_IRQ, 0), diff --git a/sys/dev/vmm/vmm_dev.c b/sys/dev/vmm/vmm_dev.c index 09fd3a9048bd..0df21402683d 100644 --- a/sys/dev/vmm/vmm_dev.c +++ b/sys/dev/vmm/vmm_dev.c @@ -91,7 +91,7 @@ static bool vmm_initialized = false; static SLIST_HEAD(, vmmdev_softc) head; -static unsigned pr_allow_flag; +static unsigned int pr_allow_vmm_flag, pr_allow_vmm_ppt_flag; static struct sx vmmdev_mtx; SX_SYSINIT(vmmdev_mtx, &vmmdev_mtx, "vmm device mutex"); @@ -115,7 +115,7 @@ static int vmm_priv_check(struct ucred *ucred) { if (jailed(ucred) && - !(ucred->cr_prison->pr_allow & pr_allow_flag)) + (ucred->cr_prison->pr_allow & pr_allow_vmm_flag) == 0) return (EPERM); return (0); @@ -459,8 +459,11 @@ vmmdev_ioctl(struct cdev *cdev, u_long cmd, caddr_t data, int fflag, if (ioctl == NULL) return (ENOTTY); - if ((ioctl->flags & VMMDEV_IOCTL_PRIV_CHECK_DRIVER) != 0) { - error = priv_check(td, PRIV_DRIVER); + if ((ioctl->flags & VMMDEV_IOCTL_PPT) != 0) { + if (jailed(td->td_ucred) && (td->td_ucred->cr_prison->pr_allow & + pr_allow_vmm_ppt_flag) == 0) + return (EPERM); + error = priv_check(td, PRIV_VMM_PPTDEV); if (error != 0) return (error); } @@ -1178,9 +1181,12 @@ vmmdev_init(void) sx_xlock(&vmmdev_mtx); error = make_dev_p(MAKEDEV_CHECKNAME, &vmmctl_cdev, &vmmctlsw, NULL, UID_ROOT, GID_WHEEL, 0600, "vmmctl"); - if (error == 0) - pr_allow_flag = prison_add_allow(NULL, "vmm", NULL, - "Allow use of vmm in a jail."); + if (error == 0) { + pr_allow_vmm_flag = prison_add_allow(NULL, "vmm", NULL, + "Allow use of vmm in a jail"); + pr_allow_vmm_ppt_flag = prison_add_allow(NULL, "vmm_ppt", NULL, + "Allow use of vmm with ppt devices in a jail"); + } sx_xunlock(&vmmdev_mtx); return (error); diff --git a/sys/dev/vmm/vmm_dev.h b/sys/dev/vmm/vmm_dev.h index f8f637fda687..4b971d88f80e 100644 --- a/sys/dev/vmm/vmm_dev.h +++ b/sys/dev/vmm/vmm_dev.h @@ -48,7 +48,7 @@ struct vmmdev_ioctl { #define VMMDEV_IOCTL_LOCK_ALL_VCPUS 0x08 #define VMMDEV_IOCTL_ALLOC_VCPU 0x10 #define VMMDEV_IOCTL_MAYBE_ALLOC_VCPU 0x20 -#define VMMDEV_IOCTL_PRIV_CHECK_DRIVER 0x40 +#define VMMDEV_IOCTL_PPT 0x40 int flags; }; diff --git a/sys/kern/kern_jail.c b/sys/kern/kern_jail.c index 5111b98bf221..369b6aca926c 100644 --- a/sys/kern/kern_jail.c +++ b/sys/kern/kern_jail.c @@ -4736,6 +4736,13 @@ prison_priv_check(struct ucred *cred, int priv) else return (EPERM); + case PRIV_VMM_PPTDEV: + /* + * Allow jailed root to manage passthrough devices. vmm(4) also + * checks for the dynamically added allow.vmm_ppt. + */ + return (0); + default: /* * In all remaining cases, deny the privilege request. This diff --git a/sys/sys/priv.h b/sys/sys/priv.h index 9c493629f7cf..1ad6a4882ffc 100644 --- a/sys/sys/priv.h +++ b/sys/sys/priv.h @@ -535,10 +535,15 @@ #define PRIV_VERIEXEC_NOVERIFY 701 /* Can override O_VERIFY */ #define PRIV_VERIEXEC_CONTROL 702 /* Can configure veriexec */ +/* + * vmm privileges. + */ +#define PRIV_VMM_PPTDEV 710 /* Can manipulate ppt devices. */ + /* * Track end of privilege list. */ -#define _PRIV_HIGHEST 703 +#define _PRIV_HIGHEST 711 /* * Validate that a named privilege is known by the privilege system. Invalid diff --git a/usr.sbin/jail/jail.8 b/usr.sbin/jail/jail.8 index 45eb7dea096d..adba3f34101b 100644 --- a/usr.sbin/jail/jail.8 +++ b/usr.sbin/jail/jail.8 @@ -833,6 +833,17 @@ The jail may access This flag is only available when the .Xr vmm 4 kernel module is loaded. +.It Va allow.vmm_ppt +The jail may configure PCI passtrough devices for use by +.Xr vmm 4 +virtual machine guests. +This allows privileged users inside the jail to manipulate physical devices +claimed by the +.Dv ppt +driver, and thus must not be configured in untrusted jails. +This flag is only available when the +.Xr vmm 4 +kernel module is loaded. .It Va linux Determine how a jail's Linux emulation environment appears. A value ofhome | help
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