Dan Magenheimer
2010-Sep-21 19:07 UTC
[Xen-devel] [PATCH] [xen-unstable] tmem: disallow bad gmfns from PV domains
Tmem: disallow bad gmfns from PV domains
Mfns for PV domains were not properly checked, potentially
allowing a buggy or malicious PV guest to crash Xen. Also,
use get_page/put_page to claim a reference to the pages
so they can''t disappear out from under tmem''s feet.
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
diff -r 5393151a737b xen/common/tmem_xen.c
--- a/xen/common/tmem_xen.c Tue Sep 14 18:26:10 2010 +0100
+++ b/xen/common/tmem_xen.c Tue Sep 21 12:56:25 2010 -0600
@@ -88,24 +88,53 @@ void tmh_copy_page(char *to, char*from)
}
#ifdef __ia64__
-static inline void *cli_mfn_to_va(tmem_cli_mfn_t cmfn, unsigned long *pcli_mfn)
+static inline void *cli_get_page(tmem_cli_mfn_t cmfn, unsigned long *pcli_mfn,
+ pfp_t **pcli_pfp, bool_t cli_write)
{
ASSERT(0);
return NULL;
}
-#define paging_mark_dirty(_x,_y) do {} while(0)
+
+static inline void cli_put_page(void *cli_va, struct page_info *cli_pfp,
+ bool_t mark_dirty)
+{
+ ASSERT(0);
+}
#else
-static inline void *cli_mfn_to_va(tmem_cli_mfn_t cmfn, unsigned long *pcli_mfn)
+static inline void *cli_get_page(tmem_cli_mfn_t cmfn, unsigned long *pcli_mfn,
+ pfp_t **pcli_pfp, bool_t cli_write)
{
unsigned long cli_mfn;
p2m_type_t t;
+ struct page_info *page;
+ int ret;
cli_mfn = mfn_x(gfn_to_mfn(p2m_get_hostp2m(current->domain), cmfn,
&t));
- if (t != p2m_ram_rw || cli_mfn == INVALID_MFN)
+ if ( t != p2m_ram_rw || !mfn_valid(cli_mfn) )
+ return NULL;
+ page = mfn_to_page(cli_mfn);
+ if ( cli_write )
+ ret = get_page_and_type(page, current->domain, PGT_writable_page);
+ else
+ ret = get_page(page, current->domain);
+ if ( !ret )
return NULL;
- if (pcli_mfn != NULL)
- *pcli_mfn = cli_mfn;
+ *pcli_mfn = cli_mfn;
+ *pcli_pfp = (pfp_t *)page;
return map_domain_page(cli_mfn);
+}
+
+static inline void cli_put_page(void *cli_va, pfp_t *cli_pfp,
+ unsigned long cli_mfn, bool_t mark_dirty)
+{
+ if ( mark_dirty )
+ {
+ put_page_and_type((struct page_info *)cli_pfp);
+ paging_mark_dirty(current->domain,cli_mfn);
+ }
+ else
+ put_page((struct page_info *)cli_pfp);
+ unmap_domain_page(cli_va);
}
#endif
@@ -113,24 +142,34 @@ EXPORT int tmh_copy_from_client(pfp_t *p
tmem_cli_mfn_t cmfn, pagesize_t tmem_offset,
pagesize_t pfn_offset, pagesize_t len, void *cli_va)
{
- unsigned long tmem_mfn;
+ unsigned long tmem_mfn, cli_mfn = 0;
void *tmem_va;
+ pfp_t *cli_pfp = NULL;
+ bool_t tmemc = cli_va != NULL; /* if true, cli_va is control-op buffer */
ASSERT(pfp != NULL);
- if ( tmem_offset || pfn_offset || len )
- if ( (cli_va == NULL) && ((cli_va = cli_mfn_to_va(cmfn,NULL))
== NULL) )
- return -EFAULT;
tmem_mfn = page_to_mfn(pfp);
tmem_va = map_domain_page(tmem_mfn);
+ if ( tmem_offset == 0 && pfn_offset == 0 && len == 0 )
+ {
+ memset(tmem_va, 0, PAGE_SIZE);
+ unmap_domain_page(tmem_va);
+ return 1;
+ }
+ if ( !tmemc )
+ {
+ cli_va = cli_get_page(cmfn, &cli_mfn, &cli_pfp, 0);
+ if ( cli_va == NULL )
+ return -EFAULT;
+ }
mb();
- if (!len && !tmem_offset && !pfn_offset)
- memset(tmem_va, 0, PAGE_SIZE);
- else if (len == PAGE_SIZE && !tmem_offset && !pfn_offset)
+ if (len == PAGE_SIZE && !tmem_offset && !pfn_offset)
tmh_copy_page(tmem_va, cli_va);
else if ( (tmem_offset+len <= PAGE_SIZE) &&
- (pfn_offset+len <= PAGE_SIZE) )
+ (pfn_offset+len <= PAGE_SIZE) )
memcpy((char *)tmem_va+tmem_offset,(char *)cli_va+pfn_offset,len);
- unmap_domain_page(cli_va);
+ if ( !tmemc )
+ cli_put_page(cli_va, cli_pfp, cli_mfn, 0);
unmap_domain_page(tmem_va);
return 1;
}
@@ -141,15 +180,24 @@ EXPORT int tmh_compress_from_client(tmem
int ret = 0;
unsigned char *dmem = this_cpu(dstmem);
unsigned char *wmem = this_cpu(workmem);
+ pfp_t *cli_pfp = NULL;
+ unsigned long cli_mfn = 0;
+ bool_t tmemc = cli_va != NULL; /* if true, cli_va is control-op buffer */
- if ( (cli_va == NULL) && (cli_va = cli_mfn_to_va(cmfn,NULL)) ==
NULL)
- return -EFAULT;
if ( dmem == NULL || wmem == NULL )
return 0; /* no buffer, so can''t compress */
+ if ( !tmemc )
+ {
+ cli_va = cli_get_page(cmfn, &cli_mfn, &cli_pfp, 0);
+ if ( cli_va == NULL )
+ return -EFAULT;
+ }
mb();
ret = lzo1x_1_compress(cli_va, PAGE_SIZE, dmem, out_len, wmem);
ASSERT(ret == LZO_E_OK);
*out_va = dmem;
+ if ( !tmemc )
+ cli_put_page(cli_va, cli_pfp, cli_mfn, 0);
unmap_domain_page(cli_va);
return 1;
}
@@ -158,14 +206,17 @@ EXPORT int tmh_copy_to_client(tmem_cli_m
pagesize_t tmem_offset, pagesize_t pfn_offset, pagesize_t len, void
*cli_va)
{
unsigned long tmem_mfn, cli_mfn = 0;
- int mark_dirty = 1;
void *tmem_va;
+ pfp_t *cli_pfp = NULL;
+ bool_t tmemc = cli_va != NULL; /* if true, cli_va is control-op buffer */
ASSERT(pfp != NULL);
- if ( cli_va != NULL )
- mark_dirty = 0;
- else if ( (cli_va = cli_mfn_to_va(cmfn,&cli_mfn)) == NULL)
- return -EFAULT;
+ if ( !tmemc )
+ {
+ cli_va = cli_get_page(cmfn, &cli_mfn, &cli_pfp, 1);
+ if ( cli_va == NULL )
+ return -EFAULT;
+ }
tmem_mfn = page_to_mfn(pfp);
tmem_va = map_domain_page(tmem_mfn);
if (len == PAGE_SIZE && !tmem_offset && !pfn_offset)
@@ -173,11 +224,8 @@ EXPORT int tmh_copy_to_client(tmem_cli_m
else if ( (tmem_offset+len <= PAGE_SIZE) && (pfn_offset+len
<= PAGE_SIZE) )
memcpy((char *)cli_va+pfn_offset,(char *)tmem_va+tmem_offset,len);
unmap_domain_page(tmem_va);
- if ( mark_dirty )
- {
- unmap_domain_page(cli_va);
- paging_mark_dirty(current->domain,cli_mfn);
- }
+ if ( !tmemc )
+ cli_put_page(cli_va, cli_pfp, cli_mfn, 1);
mb();
return 1;
}
@@ -186,22 +234,22 @@ EXPORT int tmh_decompress_to_client(tmem
size_t size, void *cli_va)
{
unsigned long cli_mfn = 0;
- int mark_dirty = 1;
+ pfp_t *cli_pfp = NULL;
size_t out_len = PAGE_SIZE;
+ bool_t tmemc = cli_va != NULL; /* if true, cli_va is control-op buffer */
int ret;
- if ( cli_va != NULL )
- mark_dirty = 0;
- else if ( (cli_va = cli_mfn_to_va(cmfn,&cli_mfn)) == NULL)
- return -EFAULT;
+ if ( !tmemc )
+ {
+ cli_va = cli_get_page(cmfn, &cli_mfn, &cli_pfp, 1);
+ if ( cli_va == NULL )
+ return -EFAULT;
+ }
ret = lzo1x_decompress_safe(tmem_va, size, cli_va, &out_len);
ASSERT(ret == LZO_E_OK);
ASSERT(out_len == PAGE_SIZE);
- if ( mark_dirty )
- {
- unmap_domain_page(cli_va);
- paging_mark_dirty(current->domain,cli_mfn);
- }
+ if ( !tmemc )
+ cli_put_page(cli_va, cli_pfp, cli_mfn, 1);
mb();
return 1;
}
@@ -211,18 +259,19 @@ EXPORT int tmh_copy_tze_to_client(tmem_c
{
void *cli_va;
unsigned long cli_mfn;
+ pfp_t *cli_pfp = NULL;
ASSERT(!(len & (sizeof(uint64_t)-1)));
ASSERT(len <= PAGE_SIZE);
ASSERT(len > 0 || tmem_va == NULL);
- if ( (cli_va = cli_mfn_to_va(cmfn,&cli_mfn)) == NULL)
+ cli_va = cli_get_page(cmfn, &cli_mfn, &cli_pfp, 1);
+ if ( cli_va == NULL )
return -EFAULT;
if ( len > 0 )
memcpy((char *)cli_va,(char *)tmem_va,len);
if ( len < PAGE_SIZE )
memset((char *)cli_va+len,0,PAGE_SIZE-len);
- unmap_domain_page(cli_va);
- paging_mark_dirty(current->domain,cli_mfn);
+ cli_put_page(cli_va, cli_pfp, cli_mfn, 1);
mb();
return 1;
}
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