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-rw-r--r--fs/nfsd/nfs4state.c27
1 files changed, 27 insertions, 0 deletions
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index a768b8701b44..34561764e5c9 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -5399,6 +5399,23 @@ nfsd4_verify_deleg_dentry(struct nfsd4_open *open, struct nfs4_file *fp,
return 0;
}
+/*
+ * We avoid breaking delegations held by a client due to its own activity, but
+ * clearing setuid/setgid bits on a write is an implicit activity and the client
+ * may not notice and continue using the old mode. Avoid giving out a delegation
+ * on setuid/setgid files when the client is requesting an open for write.
+ */
+static int
+nfsd4_verify_setuid_write(struct nfsd4_open *open, struct nfsd_file *nf)
+{
+ struct inode *inode = file_inode(nf->nf_file);
+
+ if ((open->op_share_access & NFS4_SHARE_ACCESS_WRITE) &&
+ (inode->i_mode & (S_ISUID|S_ISGID)))
+ return -EAGAIN;
+ return 0;
+}
+
static struct nfs4_delegation *
nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
struct svc_fh *parent)
@@ -5432,6 +5449,8 @@ nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
spin_lock(&fp->fi_lock);
if (nfs4_delegation_exists(clp, fp))
status = -EAGAIN;
+ else if (nfsd4_verify_setuid_write(open, nf))
+ status = -EAGAIN;
else if (!fp->fi_deleg_file) {
fp->fi_deleg_file = nf;
/* increment early to prevent fi_deleg_file from being
@@ -5472,6 +5491,14 @@ nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
if (status)
goto out_unlock;
+ /*
+ * Now that the deleg is set, check again to ensure that nothing
+ * raced in and changed the mode while we weren't lookng.
+ */
+ status = nfsd4_verify_setuid_write(open, fp->fi_deleg_file);
+ if (status)
+ goto out_unlock;
+
spin_lock(&state_lock);
spin_lock(&fp->fi_lock);
if (fp->fi_had_conflict)