| Message ID | 20200407173847.1595-3-paul@xen.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | domain context infrastructure | expand |
Hi Paul, On 07/04/2020 18:38, Paul Durrant wrote: > diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h > index 1ad34c35eb..8ab39acf0c 100644 > --- a/xen/include/public/domctl.h > +++ b/xen/include/public/domctl.h > @@ -38,7 +38,7 @@ > #include "hvm/save.h" > #include "memory.h" > > -#define XEN_DOMCTL_INTERFACE_VERSION 0x00000012 > +#define XEN_DOMCTL_INTERFACE_VERSION 0x00000013 > > /* > * NB. xen_domctl.domain is an IN/OUT parameter for this operation. > @@ -1129,6 +1129,44 @@ struct xen_domctl_vuart_op { > */ > }; > > +/* > + * Get/Set domain PV context. The same struct xen_domctl_domaincontext I think you want to update the comments to match the split. > + * is used for both commands but with slightly different field semantics > + * as follows: Reviewed-by: Julien Grall <jgrall@amazon.com> Cheers,
> -----Original Message----- > From: Julien Grall <julien@xen.org> > Sent: 20 April 2020 18:26 > To: Paul Durrant <paul@xen.org>; xen-devel@lists.xenproject.org > Cc: Paul Durrant <pdurrant@amazon.com>; Daniel De Graaf <dgdegra@tycho.nsa.gov>; Ian Jackson > <ian.jackson@eu.citrix.com>; Wei Liu <wl@xen.org>; Andrew Cooper <andrew.cooper3@citrix.com>; George > Dunlap <george.dunlap@citrix.com>; Jan Beulich <jbeulich@suse.com>; Stefano Stabellini > <sstabellini@kernel.org> > Subject: Re: [PATCH v2 2/5] xen/common/domctl: introduce XEN_DOMCTL_get/setdomaincontext > > Hi Paul, > > On 07/04/2020 18:38, Paul Durrant wrote: > > diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h > > index 1ad34c35eb..8ab39acf0c 100644 > > --- a/xen/include/public/domctl.h > > +++ b/xen/include/public/domctl.h > > @@ -38,7 +38,7 @@ > > #include "hvm/save.h" > > #include "memory.h" > > > > -#define XEN_DOMCTL_INTERFACE_VERSION 0x00000012 > > +#define XEN_DOMCTL_INTERFACE_VERSION 0x00000013 > > > > /* > > * NB. xen_domctl.domain is an IN/OUT parameter for this operation. > > @@ -1129,6 +1129,44 @@ struct xen_domctl_vuart_op { > > */ > > }; > > > > +/* > > + * Get/Set domain PV context. The same struct xen_domctl_domaincontext > > I think you want to update the comments to match the split. Oh yes. > > > + * is used for both commands but with slightly different field semantics > > + * as follows: > > Reviewed-by: Julien Grall <jgrall@amazon.com> > Thanks, Paul > > Cheers, > > > -- > Julien Grall
On 07.04.2020 19:38, Paul Durrant wrote: > @@ -358,6 +359,113 @@ static struct vnuma_info *vnuma_init(const struct xen_domctl_vnuma *uinfo, > return ERR_PTR(ret); > } > > +struct domctl_context > +{ > + void *buffer; > + size_t len; > + size_t cur; > +}; > + > +static int accumulate_size(void *priv, const void *data, size_t len) > +{ > + struct domctl_context *c = priv; > + > + if ( c->len + len < c->len ) > + return -EOVERFLOW; > + > + c->len += len; > + > + return 0; > +} > + > +static int save_data(void *priv, const void *data, size_t len) > +{ > + struct domctl_context *c = priv; > + > + if ( c->len - c->cur < len ) > + return -ENOSPC; > + > + memcpy(c->buffer + c->cur, data, len); > + c->cur += len; > + > + return 0; > +} > + > +static int getdomaincontext(struct domain *d, > + struct xen_domctl_getdomaincontext *gdc) > +{ > + struct domctl_context c = { }; Please can you use ZERO_BLOCK_PTR or some such for the buffer field, such that errnoeous use of the field would not end up as a (PV-controllable) NULL deref. (Yes, it's a domctl, but still.) This being common code you also want to get things right for Arm, irrespective of whether the code will be dead there for now. > + int rc; > + > + if ( d == current->domain ) > + return -EPERM; > + > + if ( guest_handle_is_null(gdc->buffer) ) /* query for buffer size */ > + { > + if ( gdc->size ) > + return -EINVAL; > + > + /* dry run to acquire buffer size */ > + rc = domain_save(d, accumulate_size, &c, true); > + if ( rc ) > + return rc; > + > + gdc->size = c.len; > + return 0; > + } > + > + c.len = gdc->size; > + c.buffer = xmalloc_bytes(c.len); What sizes are we looking at here? It may be better to use vmalloc() right from the start. If not, I'd like to advocate for using xmalloc_array() instead of xmalloc_bytes() - see the almost-XSA commit cf38b4926e2b. > + if ( !c.buffer ) > + return -ENOMEM; > + > + rc = domain_save(d, save_data, &c, false); > + > + gdc->size = c.cur; > + if ( !rc && copy_to_guest(gdc->buffer, c.buffer, gdc->size) ) As to my remark in patch 1 on the size field, applying to this size field too - copy_to_user{,_hvm}() don't support a 64-bit value (on y86 at least). > --- a/xen/include/public/domctl.h > +++ b/xen/include/public/domctl.h > @@ -38,7 +38,7 @@ > #include "hvm/save.h" > #include "memory.h" > > -#define XEN_DOMCTL_INTERFACE_VERSION 0x00000012 > +#define XEN_DOMCTL_INTERFACE_VERSION 0x00000013 I don't see you making any change making the interface backwards incompatible, hence no need for the bump. > @@ -1129,6 +1129,44 @@ struct xen_domctl_vuart_op { > */ > }; > > +/* > + * Get/Set domain PV context. The same struct xen_domctl_domaincontext > + * is used for both commands but with slightly different field semantics > + * as follows: > + * > + * XEN_DOMCTL_getdomaincontext > + * --------------------------- > + * > + * buffer (IN): The buffer into which the context data should be > + * copied, or NULL to query the buffer size that should > + * be allocated. > + * size (IN/OUT): If 'buffer' is NULL then the value passed in must be > + * zero, and the value passed out will be the size of the > + * buffer to allocate. > + * If 'buffer' is non-NULL then the value passed in must > + * be the size of the buffer into which data may be copied. This leaves open whether the size also gets updated in this latter case. > + */ > +struct xen_domctl_getdomaincontext { > + uint64_t size; If this is to remain 64-bits (with too large values suitably taken care of for all cases - see above), uint64_aligned_t please for consistency, if nothing else. Jan
> -----Original Message----- > From: Jan Beulich <jbeulich@suse.com> > Sent: 29 April 2020 15:51 > To: Paul Durrant <paul@xen.org> > Cc: xen-devel@lists.xenproject.org; Paul Durrant <pdurrant@amazon.com>; Daniel De Graaf > <dgdegra@tycho.nsa.gov>; Ian Jackson <ian.jackson@eu.citrix.com>; Wei Liu <wl@xen.org>; Andrew Cooper > <andrew.cooper3@citrix.com>; George Dunlap <george.dunlap@citrix.com>; Julien Grall <julien@xen.org>; > Stefano Stabellini <sstabellini@kernel.org> > Subject: Re: [PATCH v2 2/5] xen/common/domctl: introduce XEN_DOMCTL_get/setdomaincontext > > On 07.04.2020 19:38, Paul Durrant wrote: > > @@ -358,6 +359,113 @@ static struct vnuma_info *vnuma_init(const struct xen_domctl_vnuma *uinfo, > > return ERR_PTR(ret); > > } > > > > +struct domctl_context > > +{ > > + void *buffer; > > + size_t len; > > + size_t cur; > > +}; > > + > > +static int accumulate_size(void *priv, const void *data, size_t len) > > +{ > > + struct domctl_context *c = priv; > > + > > + if ( c->len + len < c->len ) > > + return -EOVERFLOW; > > + > > + c->len += len; > > + > > + return 0; > > +} > > + > > +static int save_data(void *priv, const void *data, size_t len) > > +{ > > + struct domctl_context *c = priv; > > + > > + if ( c->len - c->cur < len ) > > + return -ENOSPC; > > + > > + memcpy(c->buffer + c->cur, data, len); > > + c->cur += len; > > + > > + return 0; > > +} > > + > > +static int getdomaincontext(struct domain *d, > > + struct xen_domctl_getdomaincontext *gdc) > > +{ > > + struct domctl_context c = { }; > > Please can you use ZERO_BLOCK_PTR or some such for the buffer > field, such that errnoeous use of the field would not end up > as a (PV-controllable) NULL deref. (Yes, it's a domctl, but > still.) This being common code you also want to get things > right for Arm, irrespective of whether the code will be dead > there for now. > Ok. > > + int rc; > > + > > + if ( d == current->domain ) > > + return -EPERM; > > + > > + if ( guest_handle_is_null(gdc->buffer) ) /* query for buffer size */ > > + { > > + if ( gdc->size ) > > + return -EINVAL; > > + > > + /* dry run to acquire buffer size */ > > + rc = domain_save(d, accumulate_size, &c, true); > > + if ( rc ) > > + return rc; > > + > > + gdc->size = c.len; > > + return 0; > > + } > > + > > + c.len = gdc->size; > > + c.buffer = xmalloc_bytes(c.len); > > What sizes are we looking at here? It may be better to use vmalloc() > right from the start. Could be quite big so that seems reasonable. > If not, I'd like to advocate for using > xmalloc_array() instead of xmalloc_bytes() - see the almost-XSA > commit cf38b4926e2b. > > > + if ( !c.buffer ) > > + return -ENOMEM; > > + > > + rc = domain_save(d, save_data, &c, false); > > + > > + gdc->size = c.cur; > > + if ( !rc && copy_to_guest(gdc->buffer, c.buffer, gdc->size) ) > > As to my remark in patch 1 on the size field, applying to this size > field too - copy_to_user{,_hvm}() don't support a 64-bit value (on > y86 at least). Ok. > > > --- a/xen/include/public/domctl.h > > +++ b/xen/include/public/domctl.h > > @@ -38,7 +38,7 @@ > > #include "hvm/save.h" > > #include "memory.h" > > > > -#define XEN_DOMCTL_INTERFACE_VERSION 0x00000012 > > +#define XEN_DOMCTL_INTERFACE_VERSION 0x00000013 > > I don't see you making any change making the interface backwards > incompatible, hence no need for the bump. > Ok. > > @@ -1129,6 +1129,44 @@ struct xen_domctl_vuart_op { > > */ > > }; > > > > +/* > > + * Get/Set domain PV context. The same struct xen_domctl_domaincontext > > + * is used for both commands but with slightly different field semantics > > + * as follows: > > + * > > + * XEN_DOMCTL_getdomaincontext > > + * --------------------------- > > + * > > + * buffer (IN): The buffer into which the context data should be > > + * copied, or NULL to query the buffer size that should > > + * be allocated. > > + * size (IN/OUT): If 'buffer' is NULL then the value passed in must be > > + * zero, and the value passed out will be the size of the > > + * buffer to allocate. > > + * If 'buffer' is non-NULL then the value passed in must > > + * be the size of the buffer into which data may be copied. > > This leaves open whether the size also gets updated in this latter > case. I'll clarify. > > > + */ > > +struct xen_domctl_getdomaincontext { > > + uint64_t size; > > If this is to remain 64-bits (with too large values suitably taken > care of for all cases - see above), uint64_aligned_t please for > consistency, if nothing else. I've changed to uint32_t. Paul > > Jan
diff --git a/tools/flask/policy/modules/xen.if b/tools/flask/policy/modules/xen.if index 8eb2293a52..2bc9db4f64 100644 --- a/tools/flask/policy/modules/xen.if +++ b/tools/flask/policy/modules/xen.if @@ -53,7 +53,7 @@ define(`create_domain_common', ` allow $1 $2:domain2 { set_cpu_policy settsc setscheduler setclaim set_vnumainfo get_vnumainfo cacheflush psr_cmt_op psr_alloc soft_reset - resource_map get_cpu_policy }; + resource_map get_cpu_policy setcontext }; allow $1 $2:security check_context; allow $1 $2:shadow enable; allow $1 $2:mmu { map_read map_write adjust memorymap physmap pinpage mmuext_op updatemp }; @@ -97,7 +97,7 @@ define(`migrate_domain_out', ` allow $1 $2:hvm { gethvmc getparam }; allow $1 $2:mmu { stat pageinfo map_read }; allow $1 $2:domain { getaddrsize getvcpucontext pause destroy }; - allow $1 $2:domain2 gettsc; + allow $1 $2:domain2 { gettsc getcontext }; allow $1 $2:shadow { enable disable logdirty }; ') diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h index 58fa931de1..06ca8e9a74 100644 --- a/tools/libxc/include/xenctrl.h +++ b/tools/libxc/include/xenctrl.h @@ -867,6 +867,11 @@ int xc_domain_hvm_setcontext(xc_interface *xch, uint8_t *hvm_ctxt, uint32_t size); +int xc_domain_getcontext(xc_interface *xch, uint32_t domid, + void *ctxt_buf, size_t *size); +int xc_domain_setcontext(xc_interface *xch, uint32_t domid, + const void *ctxt_buf, size_t size); + /** * This function will return guest IO ABI protocol * diff --git a/tools/libxc/xc_domain.c b/tools/libxc/xc_domain.c index 71829c2bce..212d1489dd 100644 --- a/tools/libxc/xc_domain.c +++ b/tools/libxc/xc_domain.c @@ -537,6 +537,60 @@ int xc_domain_hvm_setcontext(xc_interface *xch, return ret; } +int xc_domain_getcontext(xc_interface *xch, uint32_t domid, + void *ctxt_buf, size_t *size) +{ + int ret; + DECLARE_DOMCTL; + DECLARE_HYPERCALL_BOUNCE(ctxt_buf, *size, XC_HYPERCALL_BUFFER_BOUNCE_OUT); + + if ( xc_hypercall_bounce_pre(xch, ctxt_buf) ) + return -1; + + domctl.cmd = XEN_DOMCTL_getdomaincontext; + domctl.domain = domid; + domctl.u.getdomaincontext.size = *size; + set_xen_guest_handle(domctl.u.setdomaincontext.buffer, ctxt_buf); + + ret = do_domctl(xch, &domctl); + + xc_hypercall_bounce_post(xch, ctxt_buf); + + if ( ret ) + return ret; + + *size = domctl.u.getdomaincontext.size; + if ( *size != domctl.u.getdomaincontext.size ) + { + errno = EOVERFLOW; + return -1; + } + + return 0; +} + +int xc_domain_setcontext(xc_interface *xch, uint32_t domid, + const void *ctxt_buf, size_t size) +{ + int ret; + DECLARE_DOMCTL; + DECLARE_HYPERCALL_BOUNCE_IN(ctxt_buf, size); + + if ( xc_hypercall_bounce_pre(xch, ctxt_buf) ) + return -1; + + domctl.cmd = XEN_DOMCTL_setdomaincontext; + domctl.domain = domid; + domctl.u.setdomaincontext.size = size; + set_xen_guest_handle(domctl.u.setdomaincontext.buffer, ctxt_buf); + + ret = do_domctl(xch, &domctl); + + xc_hypercall_bounce_post(xch, ctxt_buf); + + return ret; +} + int xc_vcpu_getcontext(xc_interface *xch, uint32_t domid, uint32_t vcpu, diff --git a/xen/common/domctl.c b/xen/common/domctl.c index a69b3b59a8..2e5c6a46d9 100644 --- a/xen/common/domctl.c +++ b/xen/common/domctl.c @@ -25,6 +25,7 @@ #include <xen/hypercall.h> #include <xen/vm_event.h> #include <xen/monitor.h> +#include <xen/save.h> #include <asm/current.h> #include <asm/irq.h> #include <asm/page.h> @@ -358,6 +359,113 @@ static struct vnuma_info *vnuma_init(const struct xen_domctl_vnuma *uinfo, return ERR_PTR(ret); } +struct domctl_context +{ + void *buffer; + size_t len; + size_t cur; +}; + +static int accumulate_size(void *priv, const void *data, size_t len) +{ + struct domctl_context *c = priv; + + if ( c->len + len < c->len ) + return -EOVERFLOW; + + c->len += len; + + return 0; +} + +static int save_data(void *priv, const void *data, size_t len) +{ + struct domctl_context *c = priv; + + if ( c->len - c->cur < len ) + return -ENOSPC; + + memcpy(c->buffer + c->cur, data, len); + c->cur += len; + + return 0; +} + +static int getdomaincontext(struct domain *d, + struct xen_domctl_getdomaincontext *gdc) +{ + struct domctl_context c = { }; + int rc; + + if ( d == current->domain ) + return -EPERM; + + if ( guest_handle_is_null(gdc->buffer) ) /* query for buffer size */ + { + if ( gdc->size ) + return -EINVAL; + + /* dry run to acquire buffer size */ + rc = domain_save(d, accumulate_size, &c, true); + if ( rc ) + return rc; + + gdc->size = c.len; + return 0; + } + + c.len = gdc->size; + c.buffer = xmalloc_bytes(c.len); + if ( !c.buffer ) + return -ENOMEM; + + rc = domain_save(d, save_data, &c, false); + + gdc->size = c.cur; + if ( !rc && copy_to_guest(gdc->buffer, c.buffer, gdc->size) ) + rc = -EFAULT; + + xfree(c.buffer); + + return rc; +} + +static int load_data(void *priv, void *data, size_t len) +{ + struct domctl_context *c = priv; + + if ( c->len - c->cur < len ) + return -ENODATA; + + if ( data ) + memcpy(data, c->buffer + c->cur, len); + + c->cur += len; + + return 0; +} + +static int setdomaincontext(struct domain *d, + const struct xen_domctl_setdomaincontext *sdc) +{ + struct domctl_context c = { .len = sdc->size }; + int rc; + + if ( d == current->domain ) + return -EPERM; + + c.buffer = xmalloc_bytes(c.len); + if ( !c.buffer ) + return -ENOMEM; + + rc = !copy_from_guest(c.buffer, sdc->buffer, c.len) ? + domain_load(d, load_data, &c) : -EFAULT; + + xfree(c.buffer); + + return rc; +} + long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl) { long ret = 0; @@ -942,6 +1050,15 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl) copyback = 1; break; + case XEN_DOMCTL_getdomaincontext: + ret = getdomaincontext(d, &op->u.getdomaincontext); + copyback = !ret; + break; + + case XEN_DOMCTL_setdomaincontext: + ret = setdomaincontext(d, &op->u.setdomaincontext); + break; + default: ret = arch_do_domctl(op, d, u_domctl); break; diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h index 1ad34c35eb..8ab39acf0c 100644 --- a/xen/include/public/domctl.h +++ b/xen/include/public/domctl.h @@ -38,7 +38,7 @@ #include "hvm/save.h" #include "memory.h" -#define XEN_DOMCTL_INTERFACE_VERSION 0x00000012 +#define XEN_DOMCTL_INTERFACE_VERSION 0x00000013 /* * NB. xen_domctl.domain is an IN/OUT parameter for this operation. @@ -1129,6 +1129,44 @@ struct xen_domctl_vuart_op { */ }; +/* + * Get/Set domain PV context. The same struct xen_domctl_domaincontext + * is used for both commands but with slightly different field semantics + * as follows: + * + * XEN_DOMCTL_getdomaincontext + * --------------------------- + * + * buffer (IN): The buffer into which the context data should be + * copied, or NULL to query the buffer size that should + * be allocated. + * size (IN/OUT): If 'buffer' is NULL then the value passed in must be + * zero, and the value passed out will be the size of the + * buffer to allocate. + * If 'buffer' is non-NULL then the value passed in must + * be the size of the buffer into which data may be copied. + */ +struct xen_domctl_getdomaincontext { + uint64_t size; + XEN_GUEST_HANDLE_64(void) buffer; +}; + +/* XEN_DOMCTL_setdomaincontext + * --------------------------- + * + * buffer (IN): The buffer from which the context data should be + * copied. + * size (IN): The size of the buffer from which data may be copied. + * This data must include DOMAIN_SAVE_CODE_HEADER at the + * start and terminate with a DOMAIN_SAVE_CODE_END record. + * Any data beyond the DOMAIN_SAVE_CODE_END record will be + * ignored. + */ +struct xen_domctl_setdomaincontext { + uint64_t size; + XEN_GUEST_HANDLE_64(const_void) buffer; +}; + struct xen_domctl { uint32_t cmd; #define XEN_DOMCTL_createdomain 1 @@ -1210,6 +1248,8 @@ struct xen_domctl { #define XEN_DOMCTL_vuart_op 81 #define XEN_DOMCTL_get_cpu_policy 82 #define XEN_DOMCTL_set_cpu_policy 83 +#define XEN_DOMCTL_getdomaincontext 84 +#define XEN_DOMCTL_setdomaincontext 85 #define XEN_DOMCTL_gdbsx_guestmemio 1000 #define XEN_DOMCTL_gdbsx_pausevcpu 1001 #define XEN_DOMCTL_gdbsx_unpausevcpu 1002 @@ -1270,6 +1310,8 @@ struct xen_domctl { struct xen_domctl_monitor_op monitor_op; struct xen_domctl_psr_alloc psr_alloc; struct xen_domctl_vuart_op vuart_op; + struct xen_domctl_getdomaincontext getdomaincontext; + struct xen_domctl_setdomaincontext setdomaincontext; uint8_t pad[128]; } u; }; diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c index 8af8602b46..d94d0fc125 100644 --- a/xen/xsm/flask/hooks.c +++ b/xen/xsm/flask/hooks.c @@ -744,6 +744,12 @@ static int flask_domctl(struct domain *d, int cmd) case XEN_DOMCTL_get_cpu_policy: return current_has_perm(d, SECCLASS_DOMAIN2, DOMAIN2__GET_CPU_POLICY); + case XEN_DOMCTL_setdomaincontext: + return current_has_perm(d, SECCLASS_DOMAIN2, DOMAIN2__SETCONTEXT); + + case XEN_DOMCTL_getdomaincontext: + return current_has_perm(d, SECCLASS_DOMAIN2, DOMAIN2__GETCONTEXT); + default: return avc_unknown_permission("domctl", cmd); } diff --git a/xen/xsm/flask/policy/access_vectors b/xen/xsm/flask/policy/access_vectors index c055c14c26..fccfb9de82 100644 --- a/xen/xsm/flask/policy/access_vectors +++ b/xen/xsm/flask/policy/access_vectors @@ -245,6 +245,10 @@ class domain2 resource_map # XEN_DOMCTL_get_cpu_policy get_cpu_policy +# XEN_DOMCTL_setdomaincontext + setcontext +# XEN_DOMCTL_getdomaincontext + getcontext } # Similar to class domain, but primarily contains domctls related to HVM domains
These domctls provide a mechanism to get and set domain context from the toolstack. Signed-off-by: Paul Durrant <pdurrant@amazon.com> --- Cc: Daniel De Graaf <dgdegra@tycho.nsa.gov> Cc: Ian Jackson <ian.jackson@eu.citrix.com> Cc: Wei Liu <wl@xen.org> Cc: Andrew Cooper <andrew.cooper3@citrix.com> Cc: George Dunlap <george.dunlap@citrix.com> Cc: Jan Beulich <jbeulich@suse.com> Cc: Julien Grall <julien@xen.org> Cc: Stefano Stabellini <sstabellini@kernel.org> v2: - drop mask parameter - const-ify some more buffers --- tools/flask/policy/modules/xen.if | 4 +- tools/libxc/include/xenctrl.h | 5 ++ tools/libxc/xc_domain.c | 54 +++++++++++++ xen/common/domctl.c | 117 ++++++++++++++++++++++++++++ xen/include/public/domctl.h | 44 ++++++++++- xen/xsm/flask/hooks.c | 6 ++ xen/xsm/flask/policy/access_vectors | 4 + 7 files changed, 231 insertions(+), 3 deletions(-)