> On Friday 1999-04-16 18:23, Trond Myklebust wrote: | | If it
> doesn't work with the 0.7.2 patch, do you think you could |
> provide me with a tcpdump of the NFS traffic between the client
> and | server? I think the problems of flushing of write
> requests is fixed | now.
> I'm not sure if this is the same problem, but permission
> checking also fails in the following cases (note that mount is
> setuid):
> $ mount > x ; ls -l x; sleep 10; ls -l x -rw-r--r-- 1 dicks
> sec 3344 Apr 16 20:19 x -rw-r--r-- 1 dicks sec 0 Apr 16 20:19
> x $ mount > x ; ls -l x; wc x; ls -l x -rw-r--r-- 1 dicks sec
> 3344 Apr 16 20:19 x wc: x: Input/output error
> 0 0 0 x
> -rw-r--r-- 1 dicks sec 0 Apr 16 20:19 x
> This is with kernel 2.2.5 + nfsv3-0.7.3 patch, but older 2.1
> kernels have similar behavior. The NFS server is an Alpha
> running Digital UNIX. The same example works in the 2.0.36
> kernel:
<snip>
> I think the problem is that the permissions are checked on
> every file operation, although it is sufficient to have
> appropriate permissions when the file is opened by the shell.
Your diagnosis is entirely correct. The answer, I think, is to reset
the fsuid/fsgid to that recorded in the file structure, since that is
set to the value of the fsuid/fsgid that was used when the file was
opened.
The appended patch (based on what I'm now using in the NFSv3 patches)
should be correct for linux-2.2.5. It's untested but (in the words of
Linus) 'obviously correct'...
Cheers,
Trond
diff -u --recursive --new-file linux-2.2.5/fs/nfs/read.c linux-2.2.5-patched/fs/nfs/read.c
--- linux-2.2.5/fs/nfs/read.c Tue Dec 22 18:37:43 1998
+++ linux-2.2.5-patched/fs/nfs/read.c Sat Apr 17 14:23:53 1999
@@ -226,11 +226,13 @@
struct dentry *dentry = file->f_dentry;
struct inode *inode = dentry->d_inode;
int error;
+ NFS_PERM_VARDEF;
dprintk("NFS: nfs_readpage (%p %ld@%ld)\n",
page, PAGE_SIZE, page->offset);
atomic_inc(&page->count);
set_bit(PG_locked, &page->flags);
+ NFS_SET_PERM(file);
/*
* Try to flush any pending writes to the file..
@@ -260,5 +262,6 @@
out_free:
free_page(page_address(page));
out:
+ NFS_CLEAR_PERM;
return error;
}
diff -u --recursive --new-file linux-2.2.5/fs/nfs/write.c linux-2.2.5-patched/fs/nfs/write.c
--- linux-2.2.5/fs/nfs/write.c Wed Mar 3 20:17:02 1999
+++ linux-2.2.5-patched/fs/nfs/write.c Sat Apr 17 14:32:55 1999
@@ -414,11 +414,13 @@
struct nfs_wreq *req;
int synchronous = sync;
int retval;
+ NFS_PERM_VARDEF;
dprintk("NFS: nfs_updatepage(%s/%s %d@%ld, sync=%d)\n",
dentry->d_parent->d_name.name, dentry->d_name.name,
count, page->offset+offset, sync);
+ NFS_SET_PERM(file);
/*
* Try to find a corresponding request on the writeback queue.
* If there is one, we can be sure that this request is not
@@ -437,13 +439,18 @@
* If wsize is smaller than page size, update and write
* page synchronously.
*/
- if (NFS_SERVER(inode)->wsize < PAGE_SIZE)
- return nfs_writepage_sync(dentry, inode, page, offset, count);
+ if (NFS_SERVER(inode)->wsize < PAGE_SIZE) {
+ status = nfs_writepage_sync(dentry, inode, page, offset, count);
+ NFS_CLEAR_PERM;
+ return status;
+ }
/* Create the write request. */
req = create_write_request(file, page, offset, count);
- if (!req)
+ if (!req) {
+ NFS_CLEAR_PERM;
return -ENOBUFS;
+ }
/*
* Ok, there's another user of this page with the new request..
@@ -476,6 +483,7 @@
}
free_write_request(req);
+ NFS_CLEAR_PERM;
return retval;
}
diff -u --recursive --new-file linux-2.2.5/include/linux/nfs_fs.h linux-2.2.5-patched/include/linux/nfs_fs.h
--- linux-2.2.5/include/linux/nfs_fs.h Sun Mar 28 20:03:31 1999
+++ linux-2.2.5-patched/include/linux/nfs_fs.h Sat Apr 17 14:34:41 1999
@@ -80,6 +80,26 @@
#define NFS_REVALIDATING(inode) (NFS_FLAGS(inode) & NFS_INO_REVALIDATE)
#define NFS_WRITEBACK(inode) ((inode)->u.nfs_i.writeback)
+#define NFS_PERM_VARDEF \
+ int old_fsuid, old_fsgid; \
+ kernel_cap_t old_cap;
+
+#define NFS_SET_PERM(file) \
+ old_fsuid = current->fsuid; \
+ old_fsgid = current->fsgid; \
+ old_cap = current->cap_effective; \
+ current->fsuid = (file)->f_uid; \
+ current->fsgid = (file)->f_gid; \
+ if (current->uid) \
+ cap_clear(current->cap_effective); \
+ else \
+ current->cap_effective = current->cap_permitted;
+
+#define NFS_CLEAR_PERM \
+ current->fsuid = old_fsuid; \
+ current->fsgid = old_fsgid; \
+ current->cap_effective = old_cap;
+
/*
* These are the default flags for swap requests
*/
-
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