Ignore the address parameter in the various file_mmap() security checks

when CONFIG_MMU=n as the address hint is ignored under those
circumstances, and in any case the minimum mapping address check is
pointless in NOMMU mode.
Signed-off-by: David Howells <dhowells@redhat.com>
Reported-by: Graff Yang <graf.yang@analog.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/security.h

@@ -609,6 +609,7 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
  *	@reqprot contains the protection requested by the application.
  *	@prot contains the protection that will be applied by the kernel.
  *	@flags contains the operational flags.
+ *	@addr contains the mapping address, and should be ignored in NOMMU mode.
  *	Return 0 if permission is granted.
  * @file_mprotect:
  *	Check permissions before changing memory access permissions.

mm/nommu.c

@@ -974,7 +974,7 @@ static int validate_mmap_request(struct file *file,
 	}
 
 	/* allow the security API to have its say */
-	ret = security_file_mmap(file, reqprot, prot, flags, addr, 0);
+	ret = security_file_mmap(file, reqprot, prot, flags, 0, 0);
 	if (ret < 0)
 		return ret;
 

security/commoncap.c

@@ -1005,6 +1005,7 @@ int cap_file_mmap(struct file *file, unsigned long reqprot,
 {
 	int ret = 0;
 
+#ifdef CONFIG_MMU
 	if (addr < dac_mmap_min_addr) {
 		ret = cap_capable(current, current_cred(), CAP_SYS_RAWIO,
 				  SECURITY_CAP_AUDIT);
@@ -1012,5 +1013,6 @@ int cap_file_mmap(struct file *file, unsigned long reqprot,
 		if (ret == 0)
 			current->flags |= PF_SUPERPRIV;
 	}
+#endif
 	return ret;
 }

security/selinux/hooks.c

@@ -3046,6 +3046,7 @@ static int selinux_file_mmap(struct file *file, unsigned long reqprot,
 			     unsigned long addr, unsigned long addr_only)
 {
 	int rc = 0;
+#ifdef CONFIG_MMU
 	u32 sid = current_sid();
 
 	/*
@@ -3060,6 +3061,7 @@ static int selinux_file_mmap(struct file *file, unsigned long reqprot,
 		if (rc)
 			return rc;
 	}
+#endif
 
 	/* do DAC check on address space usage */
 	rc = cap_file_mmap(file, reqprot, prot, flags, addr, addr_only);