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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: 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>
Subject: [RFC PATCH v3 1/8] Use refcount_t for ucounts reference counting
Date: Fri, 15 Jan 2021 15:57:22 +0100	[thread overview]
Message-ID: <116c7669744404364651e3b380db2d82bb23f983.1610722473.git.gladkov.alexey@gmail.com> (raw)
In-Reply-To: <cover.1610722473.git.gladkov.alexey@gmail.com>

Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com>
---
 include/linux/user_namespace.h |  2 +-
 kernel/ucount.c                | 20 +++++++-------------
 2 files changed, 8 insertions(+), 14 deletions(-)

diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 64cf8ebdc4ec..f84fc2d9ce20 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -92,7 +92,7 @@ struct ucounts {
 	struct hlist_node node;
 	struct user_namespace *ns;
 	kuid_t uid;
-	int count;
+	refcount_t count;
 	atomic_t ucount[UCOUNT_COUNTS];
 };
 
diff --git a/kernel/ucount.c b/kernel/ucount.c
index 11b1596e2542..82acd2226460 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -141,7 +141,8 @@ static struct ucounts *get_ucounts(struct user_namespace *ns, kuid_t uid)
 
 		new->ns = ns;
 		new->uid = uid;
-		new->count = 0;
+
+		refcount_set(&new->count, 0);
 
 		spin_lock_irq(&ucounts_lock);
 		ucounts = find_ucounts(ns, uid, hashent);
@@ -152,10 +153,7 @@ static struct ucounts *get_ucounts(struct user_namespace *ns, kuid_t uid)
 			ucounts = new;
 		}
 	}
-	if (ucounts->count == INT_MAX)
-		ucounts = NULL;
-	else
-		ucounts->count += 1;
+	refcount_inc(&ucounts->count);
 	spin_unlock_irq(&ucounts_lock);
 	return ucounts;
 }
@@ -164,15 +162,11 @@ static void put_ucounts(struct ucounts *ucounts)
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&ucounts_lock, flags);
-	ucounts->count -= 1;
-	if (!ucounts->count)
+	if (refcount_dec_and_lock_irqsave(&ucounts->count, &ucounts_lock, &flags)) {
 		hlist_del_init(&ucounts->node);
-	else
-		ucounts = NULL;
-	spin_unlock_irqrestore(&ucounts_lock, flags);
-
-	kfree(ucounts);
+		spin_unlock_irqrestore(&ucounts_lock, flags);
+		kfree(ucounts);
+	}
 }
 
 static inline bool atomic_inc_below(atomic_t *v, int u)
-- 
2.29.2

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WARNING: multiple messages have this Message-ID (diff)
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 1/8] Use refcount_t for ucounts reference counting
Date: Fri, 15 Jan 2021 15:57:22 +0100	[thread overview]
Message-ID: <116c7669744404364651e3b380db2d82bb23f983.1610722473.git.gladkov.alexey@gmail.com> (raw)
In-Reply-To: <cover.1610722473.git.gladkov.alexey@gmail.com>

Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com>
---
 include/linux/user_namespace.h |  2 +-
 kernel/ucount.c                | 20 +++++++-------------
 2 files changed, 8 insertions(+), 14 deletions(-)

diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 64cf8ebdc4ec..f84fc2d9ce20 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -92,7 +92,7 @@ struct ucounts {
 	struct hlist_node node;
 	struct user_namespace *ns;
 	kuid_t uid;
-	int count;
+	refcount_t count;
 	atomic_t ucount[UCOUNT_COUNTS];
 };
 
diff --git a/kernel/ucount.c b/kernel/ucount.c
index 11b1596e2542..82acd2226460 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -141,7 +141,8 @@ static struct ucounts *get_ucounts(struct user_namespace *ns, kuid_t uid)
 
 		new->ns = ns;
 		new->uid = uid;
-		new->count = 0;
+
+		refcount_set(&new->count, 0);
 
 		spin_lock_irq(&ucounts_lock);
 		ucounts = find_ucounts(ns, uid, hashent);
@@ -152,10 +153,7 @@ static struct ucounts *get_ucounts(struct user_namespace *ns, kuid_t uid)
 			ucounts = new;
 		}
 	}
-	if (ucounts->count == INT_MAX)
-		ucounts = NULL;
-	else
-		ucounts->count += 1;
+	refcount_inc(&ucounts->count);
 	spin_unlock_irq(&ucounts_lock);
 	return ucounts;
 }
@@ -164,15 +162,11 @@ static void put_ucounts(struct ucounts *ucounts)
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&ucounts_lock, flags);
-	ucounts->count -= 1;
-	if (!ucounts->count)
+	if (refcount_dec_and_lock_irqsave(&ucounts->count, &ucounts_lock, &flags)) {
 		hlist_del_init(&ucounts->node);
-	else
-		ucounts = NULL;
-	spin_unlock_irqrestore(&ucounts_lock, flags);
-
-	kfree(ucounts);
+		spin_unlock_irqrestore(&ucounts_lock, flags);
+		kfree(ucounts);
+	}
 }
 
 static inline bool atomic_inc_below(atomic_t *v, int u)
-- 
2.29.2


  reply	other threads:[~2021-01-15 14:59 UTC|newest]

Thread overview: 54+ 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 ` Alexey Gladkov
2021-01-15 14:57 ` Alexey Gladkov [this message]
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  6:06     ` kernel test robot
2021-01-18  6:06     ` 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 19:14     ` Linus Torvalds
2021-01-18 19:14     ` Linus Torvalds
2021-01-18 19:45     ` Alexey Gladkov
2021-01-18 19:45       ` Alexey Gladkov
2021-01-18 20:34       ` Linus Torvalds
2021-01-18 20:34         ` Linus Torvalds
2021-01-18 20:34         ` Linus Torvalds
2021-01-18 20:56         ` Alexey Gladkov
2021-01-18 20:56           ` Alexey Gladkov
2021-01-19  4:35           ` Kaiwan N Billimoria
2021-01-19  4:35             ` Kaiwan N Billimoria
2021-01-19  4:35             ` Kaiwan N Billimoria
2021-01-20  1:57           ` Eric W. Biederman
2021-01-20  1:57             ` Eric W. Biederman
2021-01-20  1:57             ` Eric W. Biederman
2021-01-20  1:58             ` Eric W. Biederman
2021-01-20  1:58               ` Eric W. Biederman
2021-01-20  1:58               ` Eric W. Biederman
2021-01-21 12:04             ` Alexey Gladkov
2021-01-21 12:04               ` Alexey Gladkov
2021-01-21 15:50               ` Eric W. Biederman
2021-01-21 15:50                 ` Eric W. Biederman
2021-01-21 15:50                 ` Eric W. Biederman
2021-01-21 16:07                 ` Alexey Gladkov
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
2021-01-15 14:57   ` Alexey Gladkov
2021-01-15 22:15   ` kernel test robot
2021-01-16  2:29   ` kernel test robot
2021-01-18  6:47   ` 14c3c8a27f: kernel_BUG_at_kernel/cred.c kernel test robot
2021-01-18  6:47     ` kernel test robot
2021-01-18  6:47     ` kernel test robot
2021-01-18  8:31   ` [PATCH v4 2/8] Add a reference to ucounts for each cred Alexey Gladkov
2021-01-18  8:31     ` 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   ` Alexey Gladkov
2021-01-15 14:57 ` [RFC PATCH v3 4/8] Move RLIMIT_MSGQUEUE " Alexey Gladkov
2021-01-15 14:57   ` Alexey Gladkov
2021-01-15 14:57 ` [RFC PATCH v3 5/8] Move RLIMIT_SIGPENDING " Alexey Gladkov
2021-01-15 14:57   ` Alexey Gladkov
2021-01-15 14:57 ` [RFC PATCH v3 6/8] Move RLIMIT_MEMLOCK " Alexey Gladkov
2021-01-15 14:57   ` Alexey Gladkov
2021-01-15 14:57 ` [RFC PATCH v3 7/8] Move RLIMIT_NPROC check to the place where we increment the counter Alexey Gladkov
2021-01-15 14:57   ` Alexey Gladkov
2021-01-15 14:57 ` [RFC PATCH v3 8/8] kselftests: Add test to check for rlimit changes in different user namespaces Alexey Gladkov
2021-01-15 14:57   ` Alexey Gladkov

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