---

yaml --- r: 59221 b: refs/heads/master c: ed03218 h: refs/heads/master i: 59219: 53897c8 v: v3
git-mirror · Jul 12, 2007 · 67d2bbc · 67d2bbc
1 parent bc3d1b5
commit 67d2bbc
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Showing 14 changed files with 71 additions and 16 deletions.
diff --git a/[refs] b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 13bddc2e9d591e31bf20020dc19ea6ca85de420e
+refs/heads/master: ed0321895182ffb6ecf210e066d87911b270d587
diff --git a/trunk/Documentation/sysctl/vm.txt b/trunk/Documentation/sysctl/vm.txt
@@ -31,6 +31,7 @@ Currently, these files are in /proc/sys/vm:
 - min_unmapped_ratio
 - min_slab_ratio
 - panic_on_oom
+- mmap_min_address
 
 ==============================================================
 
@@ -216,3 +217,17 @@ above-mentioned.
 The default value is 0.
 1 and 2 are for failover of clustering. Please select either
 according to your policy of failover.
+
+==============================================================
+
+mmap_min_addr
+
+This file indicates the amount of address space  which a user process will
+be restricted from mmaping.  Since kernel null dereference bugs could
+accidentally operate based on the information in the first couple of pages
+of memory userspace processes should not be allowed to write to them.  By
+default this value is set to 0 and no protections will be enforced by the
+security module.  Setting this value to something like 64k will allow the
+vast majority of applications to work correctly and provide defense in depth
+against future potential kernel bugs.
+
diff --git a/trunk/include/linux/security.h b/trunk/include/linux/security.h
@@ -71,6 +71,7 @@ struct xfrm_user_sec_ctx;
 extern int cap_netlink_send(struct sock *sk, struct sk_buff *skb);
 extern int cap_netlink_recv(struct sk_buff *skb, int cap);
 
+extern unsigned long mmap_min_addr;
 /*
  * Values used in the task_security_ops calls
  */
@@ -1241,8 +1242,9 @@ struct security_operations {
 	int (*file_ioctl) (struct file * file, unsigned int cmd,
 			   unsigned long arg);
 	int (*file_mmap) (struct file * file,
-			  unsigned long reqprot,
-			  unsigned long prot, unsigned long flags);
+			  unsigned long reqprot, unsigned long prot,
+			  unsigned long flags, unsigned long addr,
+			  unsigned long addr_only);
 	int (*file_mprotect) (struct vm_area_struct * vma,
 			      unsigned long reqprot,
 			      unsigned long prot);
@@ -1814,9 +1816,12 @@ static inline int security_file_ioctl (struct file *file, unsigned int cmd,
 
 static inline int security_file_mmap (struct file *file, unsigned long reqprot,
 				      unsigned long prot,
-				      unsigned long flags)
+				      unsigned long flags,
+				      unsigned long addr,
+				      unsigned long addr_only)
 {
-	return security_ops->file_mmap (file, reqprot, prot, flags);
+	return security_ops->file_mmap (file, reqprot, prot, flags, addr,
+					addr_only);
 }
 
 static inline int security_file_mprotect (struct vm_area_struct *vma,
@@ -2489,7 +2494,9 @@ static inline int security_file_ioctl (struct file *file, unsigned int cmd,
 
 static inline int security_file_mmap (struct file *file, unsigned long reqprot,
 				      unsigned long prot,
-				      unsigned long flags)
+				      unsigned long flags,
+				      unsigned long addr,
+				      unsigned long addr_only)
 {
 	return 0;
 }

diff --git a/trunk/kernel/sysctl.c b/trunk/kernel/sysctl.c
@@ -949,6 +949,16 @@ static ctl_table vm_table[] = {
 		.strategy	= &sysctl_jiffies,
 	},
 #endif
+#ifdef CONFIG_SECURITY
+	{
+		.ctl_name	= CTL_UNNUMBERED,
+		.procname	= "mmap_min_addr",
+		.data		= &mmap_min_addr,
+		.maxlen         = sizeof(unsigned long),
+		.mode		= 0644,
+		.proc_handler	= &proc_doulongvec_minmax,
+	},
+#endif
 #if defined(CONFIG_X86_32) || \
    (defined(CONFIG_SUPERH) && defined(CONFIG_VSYSCALL))
 	{

diff --git a/trunk/mm/mmap.c b/trunk/mm/mmap.c
@@ -1023,10 +1023,10 @@ unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
 		}
 	}
 
-	error = security_file_mmap(file, reqprot, prot, flags);
+	error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
 	if (error)
 		return error;
-		
+
 	/* Clear old maps */
 	error = -ENOMEM;
 munmap_back:

diff --git a/trunk/mm/mremap.c b/trunk/mm/mremap.c
@@ -291,6 +291,10 @@ unsigned long do_mremap(unsigned long addr,
 		if ((addr <= new_addr) && (addr+old_len) > new_addr)
 			goto out;
 
+		ret = security_file_mmap(0, 0, 0, 0, new_addr, 1);
+		if (ret)
+			goto out;
+
 		ret = do_munmap(mm, new_addr, new_len);
 		if (ret)
 			goto out;
@@ -390,8 +394,13 @@ unsigned long do_mremap(unsigned long addr,
 
 			new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
 						vma->vm_pgoff, map_flags);
-			ret = new_addr;
-			if (new_addr & ~PAGE_MASK)
+			if (new_addr & ~PAGE_MASK) {
+				ret = new_addr;
+				goto out;
+			}
+
+			ret = security_file_mmap(0, 0, 0, 0, new_addr, 1);
+			if (ret)
 				goto out;
 		}
 		ret = move_vma(vma, addr, old_len, new_len, new_addr);

diff --git a/trunk/mm/nommu.c b/trunk/mm/nommu.c
@@ -639,7 +639,7 @@ static int validate_mmap_request(struct file *file,
 	}
 
 	/* allow the security API to have its say */
-	ret = security_file_mmap(file, reqprot, prot, flags);
+	ret = security_file_mmap(file, reqprot, prot, flags, addr, 0);
 	if (ret < 0)
 		return ret;
 

diff --git a/trunk/security/dummy.c b/trunk/security/dummy.c
@@ -420,8 +420,12 @@ static int dummy_file_ioctl (struct file *file, unsigned int command,
 
 static int dummy_file_mmap (struct file *file, unsigned long reqprot,
 			    unsigned long prot,
-			    unsigned long flags)
+			    unsigned long flags,
+			    unsigned long addr,
+			    unsigned long addr_only)
 {
+	if (addr < mmap_min_addr)
+		return -EACCES;
 	return 0;
 }
 

diff --git a/trunk/security/security.c b/trunk/security/security.c
@@ -24,6 +24,7 @@ extern struct security_operations dummy_security_ops;
 extern void security_fixup_ops(struct security_operations *ops);
 
 struct security_operations *security_ops;	/* Initialized to NULL */
+unsigned long mmap_min_addr;		/* 0 means no protection */
 
 static inline int verify(struct security_operations *ops)
 {
@@ -176,4 +177,5 @@ EXPORT_SYMBOL_GPL(register_security);
 EXPORT_SYMBOL_GPL(unregister_security);
 EXPORT_SYMBOL_GPL(mod_reg_security);
 EXPORT_SYMBOL_GPL(mod_unreg_security);
+EXPORT_SYMBOL_GPL(mmap_min_addr);
 EXPORT_SYMBOL(security_ops);
diff --git a/trunk/security/selinux/hooks.c b/trunk/security/selinux/hooks.c
@@ -2569,12 +2569,16 @@ static int file_map_prot_check(struct file *file, unsigned long prot, int shared
 }
 
 static int selinux_file_mmap(struct file *file, unsigned long reqprot,
-			     unsigned long prot, unsigned long flags)
+			     unsigned long prot, unsigned long flags,
+			     unsigned long addr, unsigned long addr_only)
 {
-	int rc;
+	int rc = 0;
+	u32 sid = ((struct task_security_struct*)(current->security))->sid;
 
-	rc = secondary_ops->file_mmap(file, reqprot, prot, flags);
-	if (rc)
+	if (addr < mmap_min_addr)
+		rc = avc_has_perm(sid, sid, SECCLASS_MEMPROTECT,
+				  MEMPROTECT__MMAP_ZERO, NULL);
+	if (rc || addr_only)
 		return rc;
 
 	if (selinux_checkreqprot)

diff --git a/trunk/security/selinux/include/av_perm_to_string.h b/trunk/security/selinux/include/av_perm_to_string.h
@@ -158,3 +158,4 @@
    S_(SECCLASS_KEY, KEY__CREATE, "create")
    S_(SECCLASS_DCCP_SOCKET, DCCP_SOCKET__NODE_BIND, "node_bind")
    S_(SECCLASS_DCCP_SOCKET, DCCP_SOCKET__NAME_CONNECT, "name_connect")
+   S_(SECCLASS_MEMPROTECT, MEMPROTECT__MMAP_ZERO, "mmap_zero")
diff --git a/trunk/security/selinux/include/av_permissions.h b/trunk/security/selinux/include/av_permissions.h
@@ -823,3 +823,4 @@
 #define DCCP_SOCKET__NAME_BIND                    0x00200000UL
 #define DCCP_SOCKET__NODE_BIND                    0x00400000UL
 #define DCCP_SOCKET__NAME_CONNECT                 0x00800000UL
+#define MEMPROTECT__MMAP_ZERO                     0x00000001UL
diff --git a/trunk/security/selinux/include/class_to_string.h b/trunk/security/selinux/include/class_to_string.h
@@ -63,3 +63,4 @@
     S_("key")
     S_(NULL)
     S_("dccp_socket")
+    S_("memprotect")
diff --git a/trunk/security/selinux/include/flask.h b/trunk/security/selinux/include/flask.h
@@ -49,6 +49,7 @@
 #define SECCLASS_PACKET                                  57
 #define SECCLASS_KEY                                     58
 #define SECCLASS_DCCP_SOCKET                             60
+#define SECCLASS_MEMPROTECT                              61
 
 /*
  * Security identifier indices for initial entities