From: Alexey Gladkov <gladkov.alexey@gmail.com>
To: LKML <linux-kernel@vger.kernel.org>,
io-uring@vger.kernel.org,
Kernel Hardening <kernel-hardening@lists.openwall.com>,
Linux Containers <containers@lists.linux-foundation.org>,
linux-mm@kvack.org
Cc: Alexey Gladkov <legion@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Christian Brauner <christian.brauner@ubuntu.com>,
"Eric W . Biederman" <ebiederm@xmission.com>,
Jann Horn <jannh@google.com>, Jens Axboe <axboe@kernel.dk>,
Kees Cook <keescook@chromium.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>
Subject: [RFC PATCH v3 7/8] Move RLIMIT_NPROC check to the place where we increment the counter
Date: Fri, 15 Jan 2021 15:57:28 +0100 [thread overview]
Message-ID: <0829877fe0381f10d927bb94548021224e72f3c9.1610722474.git.gladkov.alexey@gmail.com> (raw)
In-Reply-To: <cover.1610722473.git.gladkov.alexey@gmail.com>
After calling set_user(), we always have to call commit_creds() to apply
new credentials upon the current task. There is no need to separate
limit check and counter incrementing.
Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com>
---
kernel/cred.c | 22 +++++++++++++++++-----
kernel/sys.c | 13 -------------
2 files changed, 17 insertions(+), 18 deletions(-)
diff --git a/kernel/cred.c b/kernel/cred.c
index c43e30407d22..991c43559ee8 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -487,14 +487,26 @@ int commit_creds(struct cred *new)
if (!gid_eq(new->fsgid, old->fsgid))
key_fsgid_changed(new);
- /* do it
- * RLIMIT_NPROC limits on user->processes have already been checked
- * in set_user().
- */
alter_cred_subscribers(new, 2);
if (new->user != old->user || new->user_ns != old->user_ns) {
+ bool overlimit;
+
set_cred_ucounts(new, new->user_ns, new->euid);
- inc_rlimit_ucounts(new->ucounts, UCOUNT_RLIMIT_NPROC, 1);
+
+ overlimit = inc_rlimit_ucounts_and_test(new->ucounts, UCOUNT_RLIMIT_NPROC,
+ 1, rlimit(RLIMIT_NPROC));
+
+ /*
+ * We don't fail in case of NPROC limit excess here because too many
+ * poorly written programs don't check set*uid() return code, assuming
+ * it never fails if called by root. We may still enforce NPROC limit
+ * for programs doing set*uid()+execve() by harmlessly deferring the
+ * failure to the execve() stage.
+ */
+ if (overlimit && new->user != INIT_USER)
+ current->flags |= PF_NPROC_EXCEEDED;
+ else
+ current->flags &= ~PF_NPROC_EXCEEDED;
}
rcu_assign_pointer(task->real_cred, new);
rcu_assign_pointer(task->cred, new);
diff --git a/kernel/sys.c b/kernel/sys.c
index c2734ab9474e..180c4e06064f 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -467,19 +467,6 @@ static int set_user(struct cred *new)
if (!new_user)
return -EAGAIN;
- /*
- * We don't fail in case of NPROC limit excess here because too many
- * poorly written programs don't check set*uid() return code, assuming
- * it never fails if called by root. We may still enforce NPROC limit
- * for programs doing set*uid()+execve() by harmlessly deferring the
- * failure to the execve() stage.
- */
- if (is_ucounts_overlimit(new->ucounts, UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC)) &&
- new_user != INIT_USER)
- current->flags |= PF_NPROC_EXCEEDED;
- else
- current->flags &= ~PF_NPROC_EXCEEDED;
-
free_uid(new->user);
new->user = new_user;
return 0;
--
2.29.2
next prev parent reply other threads:[~2021-01-15 15:00 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-15 14:57 [RFC PATCH v3 0/8] Count rlimits in each user namespace Alexey Gladkov
2021-01-15 14:57 ` [RFC PATCH v3 1/8] Use refcount_t for ucounts reference counting Alexey Gladkov
2021-01-18 6:06 ` c25050162e: WARNING:at_lib/refcount.c:#refcount_warn_saturate kernel test robot
2021-01-18 19:14 ` [RFC PATCH v3 1/8] Use refcount_t for ucounts reference counting Linus Torvalds
2021-01-18 19:45 ` Alexey Gladkov
2021-01-18 20:34 ` Linus Torvalds
2021-01-18 20:56 ` Alexey Gladkov
2021-01-19 4:35 ` Kaiwan N Billimoria
2021-01-20 1:57 ` Eric W. Biederman
2021-01-20 1:58 ` Eric W. Biederman
2021-01-21 12:04 ` Alexey Gladkov
2021-01-21 15:50 ` Eric W. Biederman
2021-01-21 16:07 ` Alexey Gladkov
2021-01-15 14:57 ` [RFC PATCH v3 2/8] Add a reference to ucounts for each cred Alexey Gladkov
2021-01-18 6:47 ` 14c3c8a27f: kernel_BUG_at_kernel/cred.c kernel test robot
2021-01-18 8:31 ` [PATCH v4 2/8] Add a reference to ucounts for each cred Alexey Gladkov
2021-01-15 14:57 ` [RFC PATCH v3 3/8] Move RLIMIT_NPROC counter to ucounts Alexey Gladkov
2021-01-15 14:57 ` [RFC PATCH v3 4/8] Move RLIMIT_MSGQUEUE " Alexey Gladkov
2021-01-15 14:57 ` [RFC PATCH v3 5/8] Move RLIMIT_SIGPENDING " Alexey Gladkov
2021-01-15 14:57 ` [RFC PATCH v3 6/8] Move RLIMIT_MEMLOCK " Alexey Gladkov
2021-01-15 14:57 ` Alexey Gladkov [this message]
2021-01-15 14:57 ` [RFC PATCH v3 8/8] kselftests: Add test to check for rlimit changes in different user namespaces Alexey Gladkov
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