linux-dentry-revalidation-always-revalidate-20010420

Based on collaboration with Chas Williams and Chaskiel Grundman

Always force revalidation so if call which caused caching was in another
authentication "context" we don't inadvertantly leak information.

Cases where things matter involve bad caching for negative dentries
(something fails because you don't have permission, then you authenticate
and the negative dentry is not flushed) or when you have l only and
someone with rl caused the dentry to get cached, in which case stat()
information and nothing else is leaked

diff --git a/src/afs/LINUX/osi_vnodeops.c b/src/afs/LINUX/osi_vnodeops.c
index 8127597..5958e65 100644 (file)
--- a/src/afs/LINUX/osi_vnodeops.c
+++ b/src/afs/LINUX/osi_vnodeops.c
@@ -675,67 +675,14 @@ static int afs_linux_revalidate(struct dentry *dp)
     return -code ;
 }
 
-/* Validate a dentry. Return 0 if unchanged, 1 if VFS layer should re-evaluate.
- * In kernels 2.2.10 and above, we are passed an additional flags var which
- * may have either the LOOKUP_FOLLOW OR LOOKUP_DIRECTORY set in which case
- * we are advised to follow the entry if it is a link or to make sure that 
- * it is a directory. But since the kernel itself checks these possibilities
- * later on, we shouldn't have to do it until later. Perhaps in the future..
- */
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,2,10)
 static int afs_linux_dentry_revalidate(struct dentry *dp, int flags)
 #else
 static int afs_linux_dentry_revalidate(struct dentry *dp)
 #endif
 {
-    int code;
-    cred_t *credp;
-    struct vrequest treq;
-    struct vcache *vcp = (struct vcache*)dp->d_inode;
-    struct vcache *dvcp = (struct vcache*)dp->d_parent->d_inode;
-
-
-    AFS_GLOCK();
-#ifdef AFS_LINUX24_ENV
-    lock_kernel();
-#endif
-
-    /* Make this a fast path (no crref), since it's called so often. */
-    if ((dvcp->states & CStatd)) {
-         if (dp->d_time != hgetlo(dvcp->m.DataVersion))
-              goto out_bad;
-         goto out_valid;
-    }
-    credp = crref();
-    code = afs_InitReq(&treq, credp);
-    if (!code)
-        code = afs_VerifyVCache(dvcp, &treq);
-    crfree(credp);
-    if (code)
-        goto out_bad;
-    if (dp->d_time != hgetlo(dvcp->m.DataVersion))
-        goto out_bad;
-
-out_valid:
-    if (vcp) {
-    if (*dp->d_name.name != '/' && vcp->mvstat == 2) /* root vnode */
-       check_bad_parent(dp); /* check and correct mvid */
-        /*vcache2inode(vcp);*/
-    }
-#ifdef AFS_LINUX24_ENV
-    unlock_kernel();
-#endif
-    AFS_GUNLOCK();
-
-    return 1;
-
-out_bad:
-    /* d_drop(dp); Let cached_lookup do this so shrink_dcache_parent 
-       is called */
-#ifdef AFS_LINUX24_ENV
-    unlock_kernel();
-#endif
-    AFS_GUNLOCK();
+    /* Force revalidation as this may be a different client than the
+       one which caused an entry to get cached */
     return 0;
 }