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Commit 3b7eb5e3 authored by Trond Myklebust's avatar Trond Myklebust Committed by Anna Schumaker
Browse files

NFS: When mounting, don't share filesystems between different user namespaces 



If two different containers that share the same network namespace attempt
to mount the same filesystem, we should not allow them to share the same
super block if they do not share the same user namespace, since the
user mappings on the wire will need to differ.

Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
parent c207db2f

fs/nfs/super.c

+17 −0
Original line number Diff line number Diff line
@@ -2485,6 +2485,21 @@ static int nfs_compare_super_address(struct nfs_server *server1, 
	return 1;

}



static int nfs_compare_userns(const struct nfs_server *old,

		const struct nfs_server *new)

{

	const struct user_namespace *oldns = &init_user_ns;

	const struct user_namespace *newns = &init_user_ns;



	if (old->client && old->client->cl_cred)

		oldns = old->client->cl_cred->user_ns;

	if (new->client && new->client->cl_cred)

		newns = new->client->cl_cred->user_ns;

	if (oldns != newns)

		return 0;

	return 1;

}



static int nfs_compare_super(struct super_block *sb, void *data)

{

	struct nfs_sb_mountdata *sb_mntdata = data;
@@ -2498,6 +2513,8 @@ static int nfs_compare_super(struct super_block *sb, void *data) 
		return 0;

	if (memcmp(&old->fsid, &server->fsid, sizeof(old->fsid)) != 0)

		return 0;

	if (!nfs_compare_userns(old, server))

		return 0;

	return nfs_compare_mount_options(sb, server, mntflags);

}