PL4425: added explicit support to retain filesharing model leveraged by proper.

Did a bit of cleanup in the filesystem specific permission functions, which
did redundant checks for readonly bind mounts.

diff --git a/fs/ext2/acl.c b/fs/ext2/acl.c
index c6e8f53..9c3e032 100644 (file)
--- a/fs/ext2/acl.c
+++ b/fs/ext2/acl.c
@@ -282,19 +282,24 @@ ext2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
        return error;
 }
 
-int
-ext2_permission(struct inode *inode, int mask, struct nameidata *nd)
+static int
+ext2_check_acl(struct inode *inode, int mask)
 {
-       int mode = inode->i_mode;
+       struct posix_acl *acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
 
-#warning MEF Get new BME patch, which I believe pushes these checks higher
-       /* Nobody gets write access to a read-only fs */
-       if ((mask & MAY_WRITE) && (IS_RDONLY(inode) ||
-           (nd && MNT_IS_RDONLY(nd->mnt))) &&
-           (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
-               return -EROFS;
+       if (acl) {
+               int error = posix_acl_permission(inode, acl, mask);
+               posix_acl_release(acl);
+               return error;
+       }
 
-       return generic_permission(inode, mask, 0);
+       return -EAGAIN;
+}
+
+int
+ext2_permission(struct inode *inode, int mask, struct nameidata *nd)
+{
+       return generic_permission(inode, mask, ext2_check_acl);
 }
 
 /*

diff --git a/fs/ext3/acl.c b/fs/ext3/acl.c
index a85b755..0425fc8 100644 (file)
--- a/fs/ext3/acl.c
+++ b/fs/ext3/acl.c
@@ -287,19 +287,24 @@ ext3_set_acl(handle_t *handle, struct inode *inode, int type,
        return error;
 }
 
-int
-ext3_permission(struct inode *inode, int mask, struct nameidata *nd)
+static int
+ext3_check_acl(struct inode *inode, int mask)
 {
-       int mode = inode->i_mode;
+       struct posix_acl *acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 
-#warning MEF Need new BME patch for 2.6.10
-       /* Nobody gets write access to a read-only fs */
-       if ((mask & MAY_WRITE) && (IS_RDONLY(inode) ||
-           (nd && MNT_IS_RDONLY(nd->mnt))) &&
-           (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
-               return -EROFS;
+       if (acl) {
+               int error = posix_acl_permission(inode, acl, mask);
+               posix_acl_release(acl);
+               return error;
+       }
 
-       return generic_permission(inode, mask, 0);
+       return -EAGAIN;
+}
+
+int
+ext3_permission(struct inode *inode, int mask, struct nameidata *nd)
+{
+       return generic_permission(inode, mask, ext3_check_acl);
 }
 
 /*

diff --git a/fs/namei.c b/fs/namei.c
index 6e74636..8a716a8 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -172,10 +172,6 @@ int generic_permission(struct inode *inode, int mask,
 {
        umode_t                 mode = inode->i_mode;
 
-       /* Prevent vservers from escaping chroot() barriers */
-       if (IS_BARRIER(inode) && !vx_check(0, VX_ADMIN))
-               return -EACCES;
-
        if (mask & MAY_WRITE) {
                /*
                 * Nobody gets write access to a read-only fs.
@@ -232,16 +228,23 @@ int generic_permission(struct inode *inode, int mask,
        return -EACCES;
 }
 
+#warning MEF: need to make CONFIG_VSERVER_FILESHARING a Kconfig option
+#define CONFIG_VSERVER_FILESHARING 1
+
 static inline int xid_permission(struct inode *inode, int mask, struct nameidata *nd)
 {
-       if (IS_BARRIER(inode) && !vx_check(0, VX_ADMIN)) {
-               vxwprintk(1, "xid=%d did hit the barrier.",
-                       vx_current_xid());
-               return -EACCES;
-       }
        if (inode->i_xid == 0)
                return 0;
-       if (vx_check(inode->i_xid, VX_ADMIN|VX_WATCH|VX_IDENT))
+
+#ifdef CONFIG_VSERVER_FILESHARING
+       /* MEF: PlanetLab FS module assumes that any file that can be
+        * named (e.g., via a cross mount) is not hidden from another
+        * context or the admin context.
+        */
+       if (vx_check(inode->i_xid,VX_STATIC|VX_DYNAMIC))
+               return 0;
+#endif
+       if (vx_check(inode->i_xid,VX_ADMIN|VX_WATCH|VX_IDENT))
                return 0;
 
        vxwprintk(1, "xid=%d denied access to %p[#%d,%lu] »%s«.",
@@ -256,6 +259,10 @@ int permission(struct inode * inode,int mask, struct nameidata *nd)
        int submask;
        umode_t mode = inode->i_mode;
 
+       /* Prevent vservers from escaping chroot() barriers */
+       if (IS_BARRIER(inode) && !vx_check(0, VX_ADMIN))
+               return -EACCES;
+
        /* Ordinary permission routines do not understand MAY_APPEND. */
        submask = mask & ~MAY_APPEND;
 
@@ -677,14 +684,27 @@ static int do_lookup(struct nameidata *nd, struct qstr *name,
        inode = dentry->d_inode;
        if (!inode)
                goto done;
-       if (!vx_check(inode->i_xid, VX_WATCH|VX_HOSTID|VX_IDENT))
-               goto hidden;
        if (inode->i_sb->s_magic == PROC_SUPER_MAGIC) {
                struct proc_dir_entry *de = PDE(inode);
 
                if (de && !vx_hide_check(0, de->vx_flags))
                        goto hidden;
        }
+#ifdef CONFIG_VSERVER_FILESHARING
+       /* MEF: PlanetLab FS module assumes that any file that can be
+        * named (e.g., via a cross mount) is not hidden from another
+        * context or the admin context.
+        */
+       if (vx_check(inode->i_xid,VX_STATIC|VX_DYNAMIC|VX_ADMIN)) {
+               /* do nothing */
+       }
+       else /* do the following check */
+#endif
+       if (!vx_check(inode->i_xid, 
+                     VX_WATCH|
+                     VX_HOSTID|
+                     VX_IDENT))
+               goto hidden;
 done:
        path->mnt = mnt;
        path->dentry = dentry;