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Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Subject: Re: [PATCH v3] cred: Propagate security_prepare_creds() error code Content-Language: en-US To: Eric Biggers Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, linux-cachefs@redhat.com, linux-cifs@vger.kernel.org, samba-technical@lists.samba.org, linux-mm@kvack.org, linux-nfs@vger.kernel.org, linux-unionfs@vger.kernel.org, linux-security-module@vger.kernel.org, netdev@vger.kernel.org, keyrings@vger.kernel.org, selinux@vger.kernel.org, serge@hallyn.com, amir73il@gmail.com, kernel-team@cloudflare.com, Jeff Moyer , Paul Moore References: <20220608150942.776446-1-fred@cloudflare.com> From: Frederick Lawler In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=cloudflare.com header.s=google header.b=R4MMR5hy; spf=none (imf19.hostedemail.com: domain of fred@cloudflare.com has no SPF policy when checking 209.85.167.180) smtp.mailfrom=fred@cloudflare.com; 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dkim=pass header.d=cloudflare.com header.s=google header.b=R4MMR5hy; spf=none (imf19.hostedemail.com: domain of fred@cloudflare.com has no SPF policy when checking 209.85.167.180) smtp.mailfrom=fred@cloudflare.com; dmarc=pass (policy=reject) header.from=cloudflare.com X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1655131729-1206 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi Eric, On 6/9/22 6:18 PM, Eric Biggers wrote: > On Wed, Jun 08, 2022 at 10:09:42AM -0500, Frederick Lawler wrote: >> diff --git a/fs/aio.c b/fs/aio.c >> index 3c249b938632..5abbe88c3ca7 100644 >> --- a/fs/aio.c >> +++ b/fs/aio.c >> @@ -1620,6 +1620,8 @@ static void aio_fsync_work(struct work_struct *work) >> static int aio_fsync(struct fsync_iocb *req, const struct iocb *iocb, >> bool datasync) >> { >> + int err; >> + >> if (unlikely(iocb->aio_buf || iocb->aio_offset || iocb->aio_nbytes || >> iocb->aio_rw_flags)) >> return -EINVAL; >> @@ -1628,8 +1630,11 @@ static int aio_fsync(struct fsync_iocb *req, const struct iocb *iocb, >> return -EINVAL; >> >> req->creds = prepare_creds(); >> - if (!req->creds) >> - return -ENOMEM; >> + if (IS_ERR(req->creds)) { >> + err = PTR_ERR(req->creds); >> + req->creds = NULL; >> + return err; >> + } > > This part is a little ugly. How about doing: > > creds = prepare_creds(); > if (IS_ERR(creds)) > return PTR_ERR(creds); > req->creds = creds; > I can do that, and same for below. >> diff --git a/fs/exec.c b/fs/exec.c >> index 0989fb8472a1..02624783e40e 100644 >> --- a/fs/exec.c >> +++ b/fs/exec.c >> @@ -1468,15 +1468,19 @@ EXPORT_SYMBOL(finalize_exec); >> */ >> static int prepare_bprm_creds(struct linux_binprm *bprm) >> { >> + int err = -ERESTARTNOINTR; >> if (mutex_lock_interruptible(¤t->signal->cred_guard_mutex)) >> - return -ERESTARTNOINTR; >> + return err; >> >> bprm->cred = prepare_exec_creds(); >> - if (likely(bprm->cred)) >> - return 0; >> + if (IS_ERR(bprm->cred)) { >> + err = PTR_ERR(bprm->cred); >> + bprm->cred = NULL; >> + mutex_unlock(¤t->signal->cred_guard_mutex); >> + return err; >> + } >> >> - mutex_unlock(¤t->signal->cred_guard_mutex); >> - return -ENOMEM; >> + return 0; >> } > > Similarly: > > static int prepare_bprm_creds(struct linux_binprm *bprm) > { > struct cred *cred; > > if (mutex_lock_interruptible(¤t->signal->cred_guard_mutex)) > return -ERESTARTNOINTR; > > cred = prepare_exec_creds(); > if (IS_ERR(cred)) { > mutex_unlock(¤t->signal->cred_guard_mutex); > return PTR_ERR(cred); > } > bprm->cred = cred; > return 0; > } > >> diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c >> index eec72ca962e2..6cf75aa83b6c 100644 >> --- a/kernel/nsproxy.c >> +++ b/kernel/nsproxy.c >> @@ -311,6 +311,7 @@ static void put_nsset(struct nsset *nsset) >> >> static int prepare_nsset(unsigned flags, struct nsset *nsset) >> { >> + int err = -ENOMEM; >> struct task_struct *me = current; >> >> nsset->nsproxy = create_new_namespaces(0, me, current_user_ns(), me->fs); >> @@ -324,6 +325,12 @@ static int prepare_nsset(unsigned flags, struct nsset *nsset) >> if (!nsset->cred) >> goto out; >> >> + if (IS_ERR(nsset->cred)) { >> + err = PTR_ERR(nsset->cred); >> + nsset->cred = NULL; >> + goto out; >> + } > > Why is the NULL check above being kept? > In the branch prior: if (flags & CLONE_NEWUSER) { nsset->cred = prepare_creds(); else nsset->cred = current_cred(); I don't see cases where others are checking for null after current_cred(), therefore I can remove that check. > Also, drivers/crypto/ccp/sev-dev.c needs to be updated. > Nice catch! I clearly missed addition after the merge window. > - Eric