From: Trond Myklebust trond.myklebust@hammerspace.com
[ Upstream commit ca05cbae2a0468e5d78e9b4605936a8bf5da328b ]
If the cached credential exists but doesn't have any expiration callback then exit early. Fix up atomicity issues when replacing the credential with a new one since the existing code could lead to refcount leaks.
Signed-off-by: Trond Myklebust trond.myklebust@hammerspace.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/nfs/inode.c | 4 ++-- fs/nfs/write.c | 41 ++++++++++++++++++++++++++++------------- include/linux/nfs_fs.h | 2 +- 3 files changed, 31 insertions(+), 16 deletions(-)
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c index 853213b3a2095..4f45281c47cfb 100644 --- a/fs/nfs/inode.c +++ b/fs/nfs/inode.c @@ -1024,7 +1024,7 @@ struct nfs_open_context *alloc_nfs_open_context(struct dentry *dentry, ctx->cred = get_cred(filp->f_cred); else ctx->cred = get_current_cred(); - ctx->ll_cred = NULL; + rcu_assign_pointer(ctx->ll_cred, NULL); ctx->state = NULL; ctx->mode = f_mode; ctx->flags = 0; @@ -1063,7 +1063,7 @@ static void __put_nfs_open_context(struct nfs_open_context *ctx, int is_sync) put_cred(ctx->cred); dput(ctx->dentry); nfs_sb_deactive(sb); - put_rpccred(ctx->ll_cred); + put_rpccred(rcu_dereference_protected(ctx->ll_cred, 1)); kfree(ctx->mdsthreshold); kfree_rcu(ctx, rcu_head); } diff --git a/fs/nfs/write.c b/fs/nfs/write.c index eae9bf1140417..773ea2c8504d6 100644 --- a/fs/nfs/write.c +++ b/fs/nfs/write.c @@ -1246,7 +1246,7 @@ nfs_key_timeout_notify(struct file *filp, struct inode *inode) struct nfs_open_context *ctx = nfs_file_open_context(filp);
if (nfs_ctx_key_to_expire(ctx, inode) && - !ctx->ll_cred) + !rcu_access_pointer(ctx->ll_cred)) /* Already expired! */ return -EACCES; return 0; @@ -1258,23 +1258,38 @@ nfs_key_timeout_notify(struct file *filp, struct inode *inode) bool nfs_ctx_key_to_expire(struct nfs_open_context *ctx, struct inode *inode) { struct rpc_auth *auth = NFS_SERVER(inode)->client->cl_auth; - struct rpc_cred *cred = ctx->ll_cred; + struct rpc_cred *cred, *new, *old = NULL; struct auth_cred acred = { .cred = ctx->cred, }; + bool ret = false;
- if (cred && !cred->cr_ops->crmatch(&acred, cred, 0)) { - put_rpccred(cred); - ctx->ll_cred = NULL; - cred = NULL; - } - if (!cred) - cred = auth->au_ops->lookup_cred(auth, &acred, 0); - if (!cred || IS_ERR(cred)) + rcu_read_lock(); + cred = rcu_dereference(ctx->ll_cred); + if (cred && !(cred->cr_ops->crkey_timeout && + cred->cr_ops->crkey_timeout(cred))) + goto out; + rcu_read_unlock(); + + new = auth->au_ops->lookup_cred(auth, &acred, 0); + if (new == cred) { + put_rpccred(new); return true; - ctx->ll_cred = cred; - return !!(cred->cr_ops->crkey_timeout && - cred->cr_ops->crkey_timeout(cred)); + } + if (IS_ERR_OR_NULL(new)) { + new = NULL; + ret = true; + } else if (new->cr_ops->crkey_timeout && + new->cr_ops->crkey_timeout(new)) + ret = true; + + rcu_read_lock(); + old = rcu_dereference_protected(xchg(&ctx->ll_cred, + RCU_INITIALIZER(new)), 1); +out: + rcu_read_unlock(); + put_rpccred(old); + return ret; }
/* diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h index b9a8b925db430..9b75448ce0df8 100644 --- a/include/linux/nfs_fs.h +++ b/include/linux/nfs_fs.h @@ -81,7 +81,7 @@ struct nfs_open_context { fl_owner_t flock_owner; struct dentry *dentry; const struct cred *cred; - struct rpc_cred *ll_cred; /* low-level cred - use to check for expiry */ + struct rpc_cred __rcu *ll_cred; /* low-level cred - use to check for expiry */ struct nfs4_state *state; fmode_t mode;