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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen stable-4.2] flask: fix reading strings from guest memory
commit 6c6b5568e8d2342de1bb653eb70aee4615430db0
Author: Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Thu Feb 6 17:36:40 2014 +0100
Commit: Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Feb 6 17:36:40 2014 +0100
flask: fix reading strings from guest memory
Since the string size is being specified by the guest, we must range
check it properly before doing allocations based on it. While for the
two cases that are exposed only to trusted guests (via policy
restriction) this just uses an arbitrary upper limit (PAGE_SIZE), for
the FLASK_[GS]ETBOOL case (which any guest can use) the upper limit
gets enforced based on the longest name across all boolean settings.
This is XSA-84.
Reported-by: Matthew Daley <mattd@xxxxxxxxxxx>
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
master commit: 6c79e0ab9ac6042e60434c02e1d99b0cf0cc3470
master date: 2014-02-06 16:33:50 +0100
---
xen/xsm/flask/flask_op.c | 21 ++++++++++++++-------
xen/xsm/flask/include/conditional.h | 4 +++-
xen/xsm/flask/ss/services.c | 17 ++++++++++-------
3 files changed, 27 insertions(+), 15 deletions(-)
diff --git a/xen/xsm/flask/flask_op.c b/xen/xsm/flask/flask_op.c
index bd4db37..60b606e 100644
--- a/xen/xsm/flask/flask_op.c
+++ b/xen/xsm/flask/flask_op.c
@@ -53,6 +53,7 @@ static DEFINE_SPINLOCK(sel_sem);
/* global data for booleans */
static int bool_num = 0;
static int *bool_pending_values = NULL;
+static size_t bool_maxstr;
static int flask_security_make_bools(void);
extern int ss_initialized;
@@ -71,9 +72,15 @@ static int domain_has_security(struct domain *d, u32 perms)
perms, NULL);
}
-static int flask_copyin_string(XEN_GUEST_HANDLE(char) u_buf, char **buf,
uint32_t size)
+static int flask_copyin_string(XEN_GUEST_HANDLE(char) u_buf, char **buf,
+ size_t size, size_t max_size)
{
- char *tmp = xmalloc_bytes(size + 1);
+ char *tmp;
+
+ if ( size > max_size )
+ return -ENOENT;
+
+ tmp = xmalloc_array(char, size + 1);
if ( !tmp )
return -ENOMEM;
@@ -99,7 +106,7 @@ static int flask_security_user(struct xen_flask_userlist
*arg)
if ( rv )
return rv;
- rv = flask_copyin_string(arg->u.user, &user, arg->size);
+ rv = flask_copyin_string(arg->u.user, &user, arg->size, PAGE_SIZE);
if ( rv )
return rv;
@@ -210,7 +217,7 @@ static int flask_security_context(struct
xen_flask_sid_context *arg)
if ( rv )
return rv;
- rv = flask_copyin_string(arg->context, &buf, arg->size);
+ rv = flask_copyin_string(arg->context, &buf, arg->size, PAGE_SIZE);
if ( rv )
return rv;
@@ -303,7 +310,7 @@ static int flask_security_resolve_bool(struct
xen_flask_boolean *arg)
if ( arg->bool_id != -1 )
return 0;
- rv = flask_copyin_string(arg->name, &name, arg->size);
+ rv = flask_copyin_string(arg->name, &name, arg->size, bool_maxstr);
if ( rv )
return rv;
@@ -334,7 +341,7 @@ static int flask_security_set_bool(struct xen_flask_boolean
*arg)
int num;
int *values;
- rv = security_get_bools(&num, NULL, &values);
+ rv = security_get_bools(&num, NULL, &values, NULL);
if ( rv != 0 )
goto out;
@@ -440,7 +447,7 @@ static int flask_security_make_bools(void)
xfree(bool_pending_values);
- ret = security_get_bools(&num, NULL, &values);
+ ret = security_get_bools(&num, NULL, &values, &bool_maxstr);
if ( ret != 0 )
goto out;
diff --git a/xen/xsm/flask/include/conditional.h
b/xen/xsm/flask/include/conditional.h
index 2fa0a30..043cfd8 100644
--- a/xen/xsm/flask/include/conditional.h
+++ b/xen/xsm/flask/include/conditional.h
@@ -13,7 +13,9 @@
#ifndef _FLASK_CONDITIONAL_H_
#define _FLASK_CONDITIONAL_H_
-int security_get_bools(int *len, char ***names, int **values);
+#include <xen/types.h>
+
+int security_get_bools(int *len, char ***names, int **values, size_t *maxstr);
int security_set_bools(int len, int *values);
diff --git a/xen/xsm/flask/ss/services.c b/xen/xsm/flask/ss/services.c
index 363f586..c4704c4 100644
--- a/xen/xsm/flask/ss/services.c
+++ b/xen/xsm/flask/ss/services.c
@@ -1900,7 +1900,7 @@ int security_find_bool(const char *name)
return rv;
}
-int security_get_bools(int *len, char ***names, int **values)
+int security_get_bools(int *len, char ***names, int **values, size_t *maxstr)
{
int i, rc = -ENOMEM;
@@ -1908,6 +1908,8 @@ int security_get_bools(int *len, char ***names, int
**values)
if ( names )
*names = NULL;
*values = NULL;
+ if ( maxstr )
+ *maxstr = 0;
*len = policydb.p_bools.nprim;
if ( !*len )
@@ -1929,16 +1931,17 @@ int security_get_bools(int *len, char ***names, int
**values)
for ( i = 0; i < *len; i++ )
{
- size_t name_len;
+ size_t name_len = strlen(policydb.p_bool_val_to_name[i]);
+
(*values)[i] = policydb.bool_val_to_struct[i]->state;
if ( names ) {
- name_len = strlen(policydb.p_bool_val_to_name[i]) + 1;
- (*names)[i] = (char*)xmalloc_array(char, name_len);
+ (*names)[i] = xmalloc_array(char, name_len + 1);
if ( !(*names)[i] )
goto err;
- strlcpy((*names)[i], policydb.p_bool_val_to_name[i], name_len);
- (*names)[i][name_len - 1] = 0;
+ strlcpy((*names)[i], policydb.p_bool_val_to_name[i], name_len + 1);
}
+ if ( maxstr && name_len > *maxstr )
+ *maxstr = name_len;
}
rc = 0;
out:
@@ -2056,7 +2059,7 @@ static int security_preserve_bools(struct policydb *p)
struct cond_bool_datum *booldatum;
struct cond_node *cur;
- rc = security_get_bools(&nbools, &bnames, &bvalues);
+ rc = security_get_bools(&nbools, &bnames, &bvalues, NULL);
if ( rc )
goto out;
for ( i = 0; i < nbools; i++ )
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.2
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