minix/kernel/system/do_safemap.c

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/* The kernel call implemented in this file:
* m_type: SYS_SAFEMAP or SYS_SAFEREVMAP or SYS_SAFEUNMAP
*
* The parameters for this kernel call are:
* SMAP_EP endpoint of the grantor
* SMAP_GID grant id
* SMAP_OFFSET offset of the grant space
* SMAP_SEG segment
* SMAP_ADDRESS address
* SMAP_BYTES bytes to be copied
* SMAP_FLAG access, writable map or not?
*/
#include <assert.h>
#include <minix/type.h>
#include <minix/safecopies.h>
#include "../system.h"
struct map_info_s {
int flag;
/* Grantor. */
endpoint_t grantor;
cp_grant_id_t gid;
vir_bytes offset;
vir_bytes address_Dseg; /* seg always is D */
/* Grantee. */
endpoint_t grantee;
int seg;
vir_bytes address;
/* Length. */
vir_bytes bytes;
};
#define MAX_MAP_INFO 20
static struct map_info_s map_info[MAX_MAP_INFO];
/*===========================================================================*
* add_info *
*===========================================================================*/
static int add_info(endpoint_t grantor, endpoint_t grantee, cp_grant_id_t gid,
vir_bytes offset, vir_bytes address_Dseg,
int seg, vir_bytes address, vir_bytes bytes)
{
int i;
for(i = 0; i < MAX_MAP_INFO; i++) {
if(map_info[i].flag == 0)
break;
}
if(i == MAX_MAP_INFO)
return EBUSY;
map_info[i].flag = 1;
map_info[i].grantor = grantor;
map_info[i].grantee = grantee;
map_info[i].gid = gid;
map_info[i].address_Dseg = address_Dseg;
map_info[i].offset = offset;
map_info[i].seg = seg;
map_info[i].address = address;
map_info[i].bytes = bytes;
return OK;
}
/*===========================================================================*
* get_revoke_info *
*===========================================================================*/
static struct map_info_s *get_revoke_info(endpoint_t grantor, int flag, int arg)
{
int i;
for(i = 0; i < MAX_MAP_INFO; i++) {
if(map_info[i].flag == 1
&& map_info[i].grantor == grantor
&& (flag ? (map_info[i].gid == arg)
: (map_info[i].address_Dseg == arg)))
return &map_info[i];
}
return NULL;
}
/*===========================================================================*
* get_unmap_info *
*===========================================================================*/
static struct map_info_s *get_unmap_info(endpoint_t grantee, int seg,
vir_bytes address)
{
int i;
for(i = 0; i < MAX_MAP_INFO; i++) {
if(map_info[i].flag == 1
&& map_info[i].grantee == grantee
&& map_info[i].seg == seg
&& map_info[i].address == address)
return &map_info[i];
}
return NULL;
}
/*===========================================================================*
* clear_info *
*===========================================================================*/
static void clear_info(struct map_info_s *p)
{
p->flag = 0;
}
/*===========================================================================*
* map_invoke_vm *
*===========================================================================*/
PUBLIC int map_invoke_vm(struct proc * caller,
int req_type, /* VMPTYPE_... COWMAP, SMAP, SUNMAP */
endpoint_t end_d, int seg_d, vir_bytes off_d,
endpoint_t end_s, int seg_s, vir_bytes off_s,
size_t size, int flag)
{
struct proc *src, *dst;
phys_bytes lin_src, lin_dst;
src = endpoint_lookup(end_s);
dst = endpoint_lookup(end_d);
lin_src = umap_local(src, seg_s, off_s, size);
lin_dst = umap_local(dst, seg_d, off_d, size);
if(lin_src == 0 || lin_dst == 0) {
printf("map_invoke_vm: error in umap_local.\n");
return EINVAL;
}
/* Make sure the linear addresses are both page aligned. */
if(lin_src % CLICK_SIZE != 0
|| lin_dst % CLICK_SIZE != 0) {
printf("map_invoke_vm: linear addresses not page aligned.\n");
return EINVAL;
}
assert(!RTS_ISSET(caller, RTS_VMREQUEST));
assert(!RTS_ISSET(caller, RTS_VMREQTARGET));
assert(!RTS_ISSET(dst, RTS_VMREQUEST));
assert(!RTS_ISSET(dst, RTS_VMREQTARGET));
RTS_SET(caller, RTS_VMREQUEST);
RTS_SET(dst, RTS_VMREQTARGET);
/* Map to the destination. */
caller->p_vmrequest.req_type = req_type;
caller->p_vmrequest.target = end_d; /* destination proc */
caller->p_vmrequest.params.map.vir_d = lin_dst; /* destination addr */
caller->p_vmrequest.params.map.ep_s = end_s; /* source process */
caller->p_vmrequest.params.map.vir_s = lin_src; /* source address */
caller->p_vmrequest.params.map.length = (vir_bytes) size;
caller->p_vmrequest.params.map.writeflag = flag;
caller->p_vmrequest.type = VMSTYPE_MAP;
/* Connect caller on vmrequest wait queue. */
if(!(caller->p_vmrequest.nextrequestor = vmrequest))
mini_notify(proc_addr(SYSTEM), VM_PROC_NR);
vmrequest = caller;
return OK;
}
/*===========================================================================*
* do_safemap *
*===========================================================================*/
PUBLIC int do_safemap(struct proc * caller, message * m_ptr)
{
endpoint_t grantor = m_ptr->SMAP_EP;
cp_grant_id_t gid = (cp_grant_id_t) m_ptr->SMAP_GID;
vir_bytes offset = (vir_bytes) m_ptr->SMAP_OFFSET;
int seg = (int) m_ptr->SMAP_SEG;
vir_bytes address = (vir_bytes) m_ptr->SMAP_ADDRESS;
vir_bytes bytes = (vir_bytes) m_ptr->SMAP_BYTES;
int flag = m_ptr->SMAP_FLAG;
vir_bytes offset_result;
endpoint_t new_grantor;
int r;
int access = CPF_MAP | CPF_READ;
/* Check the grant. We currently support safemap with both direct and
* indirect grants, as verify_grant() stores the original grantor
* transparently in new_grantor below. However, we maintain the original
* semantics associated to indirect grants only here at safemap time.
* After the mapping has been set up, if a process part of the chain
* of trust crashes or exits without revoking the mapping, the mapping
* can no longer be manually or automatically revoked for any of the
* processes lower in the chain. This solution reduces complexity but
* could be improved if we make the assumption that only one process in
* the chain of trust can effectively map the original memory region.
*/
if(flag != 0)
access |= CPF_WRITE;
r = verify_grant(grantor, caller->p_endpoint, gid, bytes, access,
offset, &offset_result, &new_grantor);
if(r != OK) {
printf("verify_grant for gid %d from %d to %d failed: %d\n",
gid, grantor, caller->p_endpoint, r);
return r;
}
/* Add map info. */
r = add_info(new_grantor, caller->p_endpoint, gid, offset,
offset_result, seg, address, bytes);
if(r != OK)
return r;
/* Invoke VM. */
return map_invoke_vm(caller, VMPTYPE_SMAP,
caller->p_endpoint, seg, address, new_grantor, D, offset_result, bytes,flag);
}
/*===========================================================================*
* safeunmap *
*===========================================================================*/
PRIVATE int safeunmap(struct proc * caller, struct map_info_s *p)
{
vir_bytes offset_result;
endpoint_t new_grantor;
int r;
r = verify_grant(p->grantor, p->grantee, p->gid, p->bytes,
CPF_MAP, p->offset, &offset_result, &new_grantor);
if(r != OK) {
printf("safeunmap: error in verify_grant.\n");
return r;
}
r = map_invoke_vm(caller, VMPTYPE_SUNMAP,
p->grantee, p->seg, p->address,
new_grantor, D, offset_result,
p->bytes, 0);
clear_info(p);
if(r != OK) {
printf("safeunmap: error in map_invoke_vm.\n");
return r;
}
return OK;
}
/*===========================================================================*
* do_saferevmap *
*===========================================================================*/
PUBLIC int do_saferevmap(struct proc * caller, message * m_ptr)
{
struct map_info_s *p;
int flag = m_ptr->SMAP_FLAG;
int arg = m_ptr->SMAP_GID; /* gid or address_Dseg */
int r;
while((p = get_revoke_info(caller->p_endpoint, flag, arg)) != NULL) {
if((r = safeunmap(caller, p)) != OK)
return r;
}
return OK;
}
/*===========================================================================*
* do_safeunmap *
*===========================================================================*/
PUBLIC int do_safeunmap(struct proc * caller, message * m_ptr)
{
vir_bytes address = (vir_bytes) m_ptr->SMAP_ADDRESS;
int seg = (int)m_ptr->SMAP_SEG;
struct map_info_s *p;
int r;
while((p = get_unmap_info(caller->p_endpoint, seg, address)) != NULL) {
if((r = safeunmap(caller, p)) != OK)
return r;
}
return OK;
}