util: move detection of shared filesystems

The code in virstoragefile.c is getting more complex as I
consolidate backing chain handling code.  But for the setuid
virt-login-shell, we don't need to crawl backing chains.  It's
easier to audit things for setuid security if there are fewer
files involved, so this patch moves the one function that
virFileOpen() was actually relying on to also live in virfile.c.

* src/util/virstoragefile.c (virStorageFileIsSharedFS)
(virStorageFileIsSharedFSType): Move...
* src/util/virfile.c (virFileIsSharedFS, virFileIsSharedFSType):
...to here, and rename.
(virFileOpenAs): Update caller.
* src/security/security_selinux.c
(virSecuritySELinuxSetFileconHelper)
(virSecuritySELinuxSetSecurityAllLabel)
(virSecuritySELinuxRestoreSecurityImageLabelInt): Likewise.
* src/security/security_dac.c
(virSecurityDACRestoreSecurityImageLabelInt): Likewise.
* src/qemu/qemu_driver.c (qemuOpenFileAs): Likewise.
* src/qemu/qemu_migration.c (qemuMigrationIsSafe): Likewise.
* src/util/virstoragefile.h: Adjust declarations.
* src/util/virfile.h: Likewise.
* src/libvirt_private.syms (virfile.h, virstoragefile.h): Move
symbols as appropriate.

Signed-off-by: Eric Blake <eblake@redhat.com>

src/libvirt_private.syms

@@ -1242,6 +1242,8 @@ virFileIsDir;
 virFileIsExecutable;
 virFileIsLink;
 virFileIsMountPoint;
+virFileIsSharedFS;
+virFileIsSharedFSType;
 virFileLinkPointsTo;
 virFileLock;
 virFileLoopDeviceAssociate;
@@ -1829,8 +1831,6 @@ virStorageFileGetMetadataFromBuf;
 virStorageFileGetMetadataFromFD;
 virStorageFileGetSCSIKey;
 virStorageFileIsClusterFS;
-virStorageFileIsSharedFS;
-virStorageFileIsSharedFSType;
 virStorageFileProbeFormat;
 virStorageFileProbeFormatFromBuf;
 virStorageFileResize;

src/qemu/qemu_driver.c

@@ -2790,7 +2790,7 @@ qemuOpenFileAs(uid_t fallback_uid, gid_t fallback_gid,
     bool bypass_security = false;
     unsigned int vfoflags = 0;
     int fd = -1;
-    int path_shared = virStorageFileIsSharedFS(path);
+    int path_shared = virFileIsSharedFS(path);
     uid_t uid = geteuid();
     gid_t gid = getegid();
 

src/qemu/qemu_migration.c

@@ -1534,7 +1534,7 @@ qemuMigrationIsSafe(virDomainDefPtr def)
             int rc;
 
             if (virDomainDiskGetType(disk) == VIR_STORAGE_TYPE_FILE) {
-                if ((rc = virStorageFileIsSharedFS(src)) < 0)
+                if ((rc = virFileIsSharedFS(src)) < 0)
                     return false;
                 else if (rc == 0)
                     continue;

src/security/security_dac.c

@@ -402,7 +402,7 @@ virSecurityDACRestoreSecurityImageLabelInt(virSecurityManagerPtr mgr,
      * VM's I/O attempts :-)
      */
     if (migrated) {
-        int rc = virStorageFileIsSharedFS(src);
+        int rc = virFileIsSharedFS(src);
         if (rc < 0)
             return -1;
         if (rc == 1) {

src/security/security_selinux.c

@@ -920,8 +920,7 @@ virSecuritySELinuxSetFileconHelper(const char *path, char *tcon, bool optional)
                 return -1;
         } else {
             const char *msg;
-            if ((virStorageFileIsSharedFSType(path,
+            if (virFileIsSharedFSType(path, VIR_FILE_SHFS_NFS) == 1 &&
-                                              VIR_STORAGE_FILE_SHFS_NFS) == 1) &&
                 security_get_boolean_active("virt_use_nfs") != 1) {
                 msg = _("Setting security context '%s' on '%s' not supported. "
                         "Consider setting virt_use_nfs");
@@ -1172,7 +1171,7 @@ virSecuritySELinuxRestoreSecurityImageLabelInt(virSecurityManagerPtr mgr,
      * VM's I/O attempts :-)
      */
     if (migrated) {
-        int rc = virStorageFileIsSharedFS(src);
+        int rc = virFileIsSharedFS(src);
         if (rc < 0)
             return -1;
         if (rc == 1) {
@@ -2323,8 +2322,7 @@ virSecuritySELinuxSetSecurityAllLabel(virSecurityManagerPtr mgr,
 
     if (stdin_path) {
         if (virSecuritySELinuxSetFilecon(stdin_path, data->content_context) < 0 &&
-            virStorageFileIsSharedFSType(stdin_path,
+            virFileIsSharedFSType(stdin_path, VIR_FILE_SHFS_NFS) != 1)
-                                         VIR_STORAGE_FILE_SHFS_NFS) != 1)
             return -1;
     }
 

src/util/virfile.c

@@ -43,6 +43,13 @@
 # include <sys/mman.h>
 #endif
 
+#ifdef __linux__
+# if HAVE_LINUX_MAGIC_H
+#  include <linux/magic.h>
+# endif
+# include <sys/statfs.h>
+#endif
+
 #if defined(__linux__) && HAVE_DECL_LO_FLAGS_AUTOCLEAR
 # include <linux/loop.h>
 # include <sys/ioctl.h>
@@ -2050,7 +2057,7 @@ virFileOpenAs(const char *path, int openflags, mode_t mode,
 
             /* On Linux we can also verify the FS-type of the
              * directory.  (this is a NOP on other platforms). */
-            if (virStorageFileIsSharedFS(path) <= 0)
+            if (virFileIsSharedFS(path) <= 0)
                 goto error;
         }
 
@@ -2646,3 +2653,116 @@ int virFilePrintf(FILE *fp, const char *msg, ...)
 
     return ret;
 }
+
+
+#ifdef __linux__
+
+# ifndef NFS_SUPER_MAGIC
+#  define NFS_SUPER_MAGIC 0x6969
+# endif
+# ifndef OCFS2_SUPER_MAGIC
+#  define OCFS2_SUPER_MAGIC 0x7461636f
+# endif
+# ifndef GFS2_MAGIC
+#  define GFS2_MAGIC 0x01161970
+# endif
+# ifndef AFS_FS_MAGIC
+#  define AFS_FS_MAGIC 0x6B414653
+# endif
+# ifndef SMB_SUPER_MAGIC
+#  define SMB_SUPER_MAGIC 0x517B
+# endif
+# ifndef CIFS_SUPER_MAGIC
+#  define CIFS_SUPER_MAGIC 0xFF534D42
+# endif
+
+int
+virFileIsSharedFSType(const char *path,
+                      int fstypes)
+{
+    char *dirpath, *p;
+    struct statfs sb;
+    int statfs_ret;
+
+    if (VIR_STRDUP(dirpath, path) < 0)
+        return -1;
+
+    do {
+
+        /* Try less and less of the path until we get to a
+         * directory we can stat. Even if we don't have 'x'
+         * permission on any directory in the path on the NFS
+         * server (assuming it's NFS), we will be able to stat the
+         * mount point, and that will properly tell us if the
+         * fstype is NFS.
+         */
+
+        if ((p = strrchr(dirpath, '/')) == NULL) {
+            virReportSystemError(EINVAL,
+                         _("Invalid relative path '%s'"), path);
+            VIR_FREE(dirpath);
+            return -1;
+        }
+
+        if (p == dirpath)
+            *(p+1) = '\0';
+        else
+            *p = '\0';
+
+        statfs_ret = statfs(dirpath, &sb);
+
+    } while ((statfs_ret < 0) && (p != dirpath));
+
+    VIR_FREE(dirpath);
+
+    if (statfs_ret < 0) {
+        virReportSystemError(errno,
+                             _("cannot determine filesystem for '%s'"),
+                             path);
+        return -1;
+    }
+
+    VIR_DEBUG("Check if path %s with FS magic %lld is shared",
+              path, (long long int)sb.f_type);
+
+    if ((fstypes & VIR_FILE_SHFS_NFS) &&
+        (sb.f_type == NFS_SUPER_MAGIC))
+        return 1;
+
+    if ((fstypes & VIR_FILE_SHFS_GFS2) &&
+        (sb.f_type == GFS2_MAGIC))
+        return 1;
+    if ((fstypes & VIR_FILE_SHFS_OCFS) &&
+        (sb.f_type == OCFS2_SUPER_MAGIC))
+        return 1;
+    if ((fstypes & VIR_FILE_SHFS_AFS) &&
+        (sb.f_type == AFS_FS_MAGIC))
+        return 1;
+    if ((fstypes & VIR_FILE_SHFS_SMB) &&
+        (sb.f_type == SMB_SUPER_MAGIC))
+        return 1;
+    if ((fstypes & VIR_FILE_SHFS_CIFS) &&
+        (sb.f_type == CIFS_SUPER_MAGIC))
+        return 1;
+
+    return 0;
+}
+#else
+int virFileIsSharedFSType(const char *path ATTRIBUTE_UNUSED,
+                          int fstypes ATTRIBUTE_UNUSED)
+{
+    /* XXX implement me :-) */
+    return 0;
+}
+#endif
+
+int virFileIsSharedFS(const char *path)
+{
+    return virFileIsSharedFSType(path,
+                                 VIR_FILE_SHFS_NFS |
+                                 VIR_FILE_SHFS_GFS2 |
+                                 VIR_FILE_SHFS_OCFS |
+                                 VIR_FILE_SHFS_AFS |
+                                 VIR_FILE_SHFS_SMB |
+                                 VIR_FILE_SHFS_CIFS);
+}

src/util/virfile.h

@@ -1,7 +1,7 @@
 /*
  * virfile.h: safer file handling
  *
- * Copyright (C) 2010-2011, 2013 Red Hat, Inc.
+ * Copyright (C) 2010-2014 Red Hat, Inc.
  * Copyright (C) 2010 IBM Corporation
  * Copyright (C) 2010 Stefan Berger
  * Copyright (C) 2010 Eric Blake
@@ -159,6 +159,17 @@ bool virFileIsDir (const char *file) ATTRIBUTE_NONNULL(1);
 bool virFileExists(const char *file) ATTRIBUTE_NONNULL(1);
 bool virFileIsExecutable(const char *file) ATTRIBUTE_NONNULL(1);
 
+enum {
+    VIR_FILE_SHFS_NFS = (1 << 0),
+    VIR_FILE_SHFS_GFS2 = (1 << 1),
+    VIR_FILE_SHFS_OCFS = (1 << 2),
+    VIR_FILE_SHFS_AFS = (1 << 3),
+    VIR_FILE_SHFS_SMB = (1 << 4),
+    VIR_FILE_SHFS_CIFS = (1 << 5),
+};
+
+int virFileIsSharedFSType(const char *path, int fstypes) ATTRIBUTE_NONNULL(1);
+int virFileIsSharedFS(const char *path) ATTRIBUTE_NONNULL(1);
 int virFileIsMountPoint(const char *file) ATTRIBUTE_NONNULL(1);
 
 int virFileGetMountSubtree(const char *mtabpath,

src/util/virstoragefile.c

@@ -28,12 +28,6 @@
 #include <unistd.h>
 #include <fcntl.h>
 #include <stdlib.h>
-#ifdef __linux__
-# if HAVE_LINUX_MAGIC_H
-#  include <linux/magic.h>
-# endif
-# include <sys/statfs.h>
-#endif
 #include "dirname.h"
 #include "viralloc.h"
 #include "virerror.h"
@@ -1283,126 +1277,15 @@ virStorageFileResize(const char *path,
     return ret;
 }
 
-#ifdef __linux__
-
-# ifndef NFS_SUPER_MAGIC
-#  define NFS_SUPER_MAGIC 0x6969
-# endif
-# ifndef OCFS2_SUPER_MAGIC
-#  define OCFS2_SUPER_MAGIC 0x7461636f
-# endif
-# ifndef GFS2_MAGIC
-#  define GFS2_MAGIC 0x01161970
-# endif
-# ifndef AFS_FS_MAGIC
-#  define AFS_FS_MAGIC 0x6B414653
-# endif
-# ifndef SMB_SUPER_MAGIC
-#  define SMB_SUPER_MAGIC 0x517B
-# endif
-# ifndef CIFS_SUPER_MAGIC
-#  define CIFS_SUPER_MAGIC 0xFF534D42
-# endif
-
-
-int virStorageFileIsSharedFSType(const char *path,
-                                 int fstypes)
-{
-    char *dirpath, *p;
-    struct statfs sb;
-    int statfs_ret;
-
-    if (VIR_STRDUP(dirpath, path) < 0)
-        return -1;
-
-    do {
-
-        /* Try less and less of the path until we get to a
-         * directory we can stat. Even if we don't have 'x'
-         * permission on any directory in the path on the NFS
-         * server (assuming it's NFS), we will be able to stat the
-         * mount point, and that will properly tell us if the
-         * fstype is NFS.
-         */
-
-        if ((p = strrchr(dirpath, '/')) == NULL) {
-            virReportSystemError(EINVAL,
-                         _("Invalid relative path '%s'"), path);
-            VIR_FREE(dirpath);
-            return -1;
-        }
-
-        if (p == dirpath)
-            *(p+1) = '\0';
-        else
-            *p = '\0';
-
-        statfs_ret = statfs(dirpath, &sb);
-
-    } while ((statfs_ret < 0) && (p != dirpath));
-
-    VIR_FREE(dirpath);
-
-    if (statfs_ret < 0) {
-        virReportSystemError(errno,
-                             _("cannot determine filesystem for '%s'"),
-                             path);
-        return -1;
-    }
-
-    VIR_DEBUG("Check if path %s with FS magic %lld is shared",
-              path, (long long int)sb.f_type);
-
-    if ((fstypes & VIR_STORAGE_FILE_SHFS_NFS) &&
-        (sb.f_type == NFS_SUPER_MAGIC))
-        return 1;
-
-    if ((fstypes & VIR_STORAGE_FILE_SHFS_GFS2) &&
-        (sb.f_type == GFS2_MAGIC))
-        return 1;
-    if ((fstypes & VIR_STORAGE_FILE_SHFS_OCFS) &&
-        (sb.f_type == OCFS2_SUPER_MAGIC))
-        return 1;
-    if ((fstypes & VIR_STORAGE_FILE_SHFS_AFS) &&
-        (sb.f_type == AFS_FS_MAGIC))
-        return 1;
-    if ((fstypes & VIR_STORAGE_FILE_SHFS_SMB) &&
-        (sb.f_type == SMB_SUPER_MAGIC))
-        return 1;
-    if ((fstypes & VIR_STORAGE_FILE_SHFS_CIFS) &&
-        (sb.f_type == CIFS_SUPER_MAGIC))
-        return 1;
-
-    return 0;
-}
-#else
-int virStorageFileIsSharedFSType(const char *path ATTRIBUTE_UNUSED,
-                                 int fstypes ATTRIBUTE_UNUSED)
-{
-    /* XXX implement me :-) */
-    return 0;
-}
-#endif
-
-int virStorageFileIsSharedFS(const char *path)
-{
-    return virStorageFileIsSharedFSType(path,
-                                        VIR_STORAGE_FILE_SHFS_NFS |
-                                        VIR_STORAGE_FILE_SHFS_GFS2 |
-                                        VIR_STORAGE_FILE_SHFS_OCFS |
-                                        VIR_STORAGE_FILE_SHFS_AFS |
-                                        VIR_STORAGE_FILE_SHFS_SMB |
-                                        VIR_STORAGE_FILE_SHFS_CIFS);
-}
 
 int virStorageFileIsClusterFS(const char *path)
 {
     /* These are coherent cluster filesystems known to be safe for
      * migration with cache != none
      */
-    return virStorageFileIsSharedFSType(path,
+    return virFileIsSharedFSType(path,
-                                        VIR_STORAGE_FILE_SHFS_GFS2 |
+                                 VIR_FILE_SHFS_GFS2 |
-                                        VIR_STORAGE_FILE_SHFS_OCFS);
+                                 VIR_FILE_SHFS_OCFS);
 }
 
 #ifdef LVS

src/util/virstoragefile.h

@@ -250,19 +250,7 @@ int virStorageFileResize(const char *path,
                          unsigned long long orig_capacity,
                          bool pre_allocate);
 
-enum {
-    VIR_STORAGE_FILE_SHFS_NFS = (1 << 0),
-    VIR_STORAGE_FILE_SHFS_GFS2 = (1 << 1),
-    VIR_STORAGE_FILE_SHFS_OCFS = (1 << 2),
-    VIR_STORAGE_FILE_SHFS_AFS = (1 << 3),
-    VIR_STORAGE_FILE_SHFS_SMB = (1 << 4),
-    VIR_STORAGE_FILE_SHFS_CIFS = (1 << 5),
-};
-
-int virStorageFileIsSharedFS(const char *path);
 int virStorageFileIsClusterFS(const char *path);
-int virStorageFileIsSharedFSType(const char *path,
-                                 int fstypes);
 
 int virStorageFileGetLVMKey(const char *path,
                             char **key);