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From: legion@kernel.org
To: LKML <linux-kernel@vger.kernel.org>,
	Kernel Hardening <kernel-hardening@lists.openwall.com>,
	Linux Containers <containers@lists.linux-foundation.org>,
	linux-mm@kvack.org
Cc: Jens Axboe <axboe@kernel.dk>, Kees Cook <keescook@chromium.org>,
	Jann Horn <jannh@google.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Oleg Nesterov <oleg@redhat.com>,
	"Eric W . Biederman" <ebiederm@xmission.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Alexey Gladkov <legion@kernel.org>,
	Christian Brauner <christian.brauner@ubuntu.com>
Subject: [PATCH v11 1/9] Increase size of ucounts to atomic_long_t
Date: Thu, 22 Apr 2021 14:27:08 +0200
Message-ID: <257aa5fb1a7d81cf0f4c34f39ada2320c4284771.1619094428.git.legion@kernel.org> (raw)
In-Reply-To: <cover.1619094428.git.legion@kernel.org>

From: Alexey Gladkov <legion@kernel.org>

RLIMIT_MSGQUEUE and RLIMIT_MEMLOCK use unsigned long to store their
counters. As a preparation for moving rlimits based on ucounts, we need
to increase the size of the variable to long.

Signed-off-by: Alexey Gladkov <legion@kernel.org>
---
 include/linux/user_namespace.h |  4 ++--
 kernel/ucount.c                | 16 ++++++++--------
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 64cf8ebdc4ec..0bb833fd41f4 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -85,7 +85,7 @@ struct user_namespace {
 	struct ctl_table_header *sysctls;
 #endif
 	struct ucounts		*ucounts;
-	int ucount_max[UCOUNT_COUNTS];
+	long ucount_max[UCOUNT_COUNTS];
 } __randomize_layout;
 
 struct ucounts {
@@ -93,7 +93,7 @@ struct ucounts {
 	struct user_namespace *ns;
 	kuid_t uid;
 	int count;
-	atomic_t ucount[UCOUNT_COUNTS];
+	atomic_long_t ucount[UCOUNT_COUNTS];
 };
 
 extern struct user_namespace init_user_ns;
diff --git a/kernel/ucount.c b/kernel/ucount.c
index 11b1596e2542..04c561751af1 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -175,14 +175,14 @@ static void put_ucounts(struct ucounts *ucounts)
 	kfree(ucounts);
 }
 
-static inline bool atomic_inc_below(atomic_t *v, int u)
+static inline bool atomic_long_inc_below(atomic_long_t *v, int u)
 {
-	int c, old;
-	c = atomic_read(v);
+	long c, old;
+	c = atomic_long_read(v);
 	for (;;) {
 		if (unlikely(c >= u))
 			return false;
-		old = atomic_cmpxchg(v, c, c+1);
+		old = atomic_long_cmpxchg(v, c, c+1);
 		if (likely(old == c))
 			return true;
 		c = old;
@@ -196,17 +196,17 @@ struct ucounts *inc_ucount(struct user_namespace *ns, kuid_t uid,
 	struct user_namespace *tns;
 	ucounts = get_ucounts(ns, uid);
 	for (iter = ucounts; iter; iter = tns->ucounts) {
-		int max;
+		long max;
 		tns = iter->ns;
 		max = READ_ONCE(tns->ucount_max[type]);
-		if (!atomic_inc_below(&iter->ucount[type], max))
+		if (!atomic_long_inc_below(&iter->ucount[type], max))
 			goto fail;
 	}
 	return ucounts;
 fail:
 	bad = iter;
 	for (iter = ucounts; iter != bad; iter = iter->ns->ucounts)
-		atomic_dec(&iter->ucount[type]);
+		atomic_long_dec(&iter->ucount[type]);
 
 	put_ucounts(ucounts);
 	return NULL;
@@ -216,7 +216,7 @@ void dec_ucount(struct ucounts *ucounts, enum ucount_type type)
 {
 	struct ucounts *iter;
 	for (iter = ucounts; iter; iter = iter->ns->ucounts) {
-		int dec = atomic_dec_if_positive(&iter->ucount[type]);
+		long dec = atomic_long_dec_if_positive(&iter->ucount[type]);
 		WARN_ON_ONCE(dec < 0);
 	}
 	put_ucounts(ucounts);
-- 
2.29.3

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Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-22 12:27 [PATCH v11 0/9] Count rlimits in each user namespace legion
2021-04-22 12:27 ` legion [this message]
2021-04-22 12:27 ` [PATCH v11 2/9] Add a reference to ucounts for each cred legion
2021-04-22 12:27 ` [PATCH v11 3/9] Use atomic_t for ucounts reference counting legion
2021-04-22 12:27 ` [PATCH v11 5/9] Reimplement RLIMIT_MSGQUEUE on top of ucounts legion
2021-04-22 12:27 ` [PATCH v11 6/9] Reimplement RLIMIT_SIGPENDING " legion
2021-04-22 12:27 ` [PATCH v11 7/9] Reimplement RLIMIT_MEMLOCK " legion
2021-04-22 12:27 ` [PATCH v11 8/9] kselftests: Add test to check for rlimit changes in different user namespaces legion
2021-04-22 12:27 ` [PATCH v11 9/9] ucounts: Set ucount_max to the largest positive value the type can hold legion
2021-04-29 14:04 [PATCH v11 4/9] Reimplement RLIMIT_NPROC on top of ucounts Dan Carpenter
2021-04-30 18:09 ` [PATCH] ucounts: Silence warning in dec_rlimit_ucounts Eric W. Biederman

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