From: Kuniyuki Iwashima <kuniyu@amazon.com>
To: "David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Luis Chamberlain <mcgrof@kernel.org>,
Kees Cook <keescook@chromium.org>,
Iurii Zaikin <yzaikin@google.com>
Cc: Kuniyuki Iwashima <kuniyu@amazon.com>,
Kuniyuki Iwashima <kuni1840@gmail.com>, <netdev@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Subject: [PATCH v1 net 05/16] sysctl: Add proc_dointvec_minmax_lockless().
Date: Tue, 5 Jul 2022 22:21:19 -0700 [thread overview]
Message-ID: <20220706052130.16368-6-kuniyu@amazon.com> (raw)
In-Reply-To: <20220706052130.16368-1-kuniyu@amazon.com>
A sysctl variable is accessed concurrently, and there is always a chance of
data-race. So, all readers and writers need some basic protection to avoid
load/store-tearing.
This patch changes proc_dointvec_minmax() to use READ_ONCE()/WRITE_ONCE()
internally to fix a data-race on the sysctl side. For now,
proc_dointvec_minmax() itself is tolerant to a data-race, but we still need
to add annotations on the other subsystem's side.
In case we miss such fixes, this patch converts proc_dointvec_minmax() to a
wrapper of proc_dointvec_minmax_lockless(). When we fix a data-race in the
other subsystem, we can explicitly set it as a handler.
Also, this patch removes proc_dointvec_minmax()'s document and adds
proc_dointvec_minmax_lockless()'s one so that no one will use
proc_dointvec_minmax() anymore.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
include/linux/sysctl.h | 1 +
kernel/sysctl.c | 19 +++++++++++++++----
2 files changed, 16 insertions(+), 4 deletions(-)
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 770ee1833c25..7f91cc625d56 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -86,6 +86,7 @@ PROC_HANDLER(proc_do_static_key);
PROC_HANDLER(proc_dobool_lockless);
PROC_HANDLER(proc_dointvec_lockless);
PROC_HANDLER(proc_douintvec_lockless);
+PROC_HANDLER(proc_dointvec_minmax_lockless);
/*
* Register a set of sysctl names by calling register_sysctl_table
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index be8a7d912180..aead731ae74b 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -879,14 +879,16 @@ static int do_proc_dointvec_minmax_conv(bool *negp, unsigned long *lvalp,
if ((param->min && *param->min > tmp) ||
(param->max && *param->max < tmp))
return -EINVAL;
- *valp = tmp;
+
+ WRITE_ONCE(*valp, tmp);
}
return 0;
}
/**
- * proc_dointvec_minmax - read a vector of integers with min/max values
+ * proc_dointvec_minmax_lockless - read/write a vector of integers with
+ * min/max values locklessly
* @table: the sysctl table
* @write: %TRUE if this is a write to the sysctl file
* @buffer: the user buffer
@@ -901,8 +903,8 @@ static int do_proc_dointvec_minmax_conv(bool *negp, unsigned long *lvalp,
*
* Returns 0 on success or -EINVAL on write when the range check fails.
*/
-int proc_dointvec_minmax(struct ctl_table *table, int write,
- void *buffer, size_t *lenp, loff_t *ppos)
+int proc_dointvec_minmax_lockless(struct ctl_table *table, int write,
+ void *buffer, size_t *lenp, loff_t *ppos)
{
struct do_proc_dointvec_minmax_conv_param param = {
.min = (int *) table->extra1,
@@ -912,6 +914,13 @@ int proc_dointvec_minmax(struct ctl_table *table, int write,
do_proc_dointvec_minmax_conv, ¶m);
}
+int proc_dointvec_minmax(struct ctl_table *table, int write,
+ void *buffer, size_t *lenp, loff_t *ppos)
+{
+ return proc_dointvec_minmax_lockless(table, write, buffer,
+ lenp, ppos);
+}
+
/**
* struct do_proc_douintvec_minmax_conv_param - proc_douintvec_minmax() range checking structure
* @min: pointer to minimum allowable value
@@ -1522,6 +1531,7 @@ PROC_HANDLER_ENOSYS(proc_do_large_bitmap);
PROC_HANDLER_ENOSYS(proc_dobool_lockless);
PROC_HANDLER_ENOSYS(proc_dointvec_lockless);
PROC_HANDLER_ENOSYS(proc_douintvec_lockless);
+PROC_HANDLER_ENOSYS(proc_dointvec_minmax_lockless);
#endif /* CONFIG_PROC_SYSCTL */
@@ -2435,3 +2445,4 @@ EXPORT_SYMBOL(proc_do_large_bitmap);
EXPORT_SYMBOL(proc_dobool_lockless);
EXPORT_SYMBOL(proc_dointvec_lockless);
EXPORT_SYMBOL(proc_douintvec_lockless);
+EXPORT_SYMBOL(proc_dointvec_minmax_lockless);
--
2.30.2
next prev parent reply other threads:[~2022-07-06 5:23 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-06 5:21 [PATCH v1 net 00/16] sysctl: Fix data-races around ipv4_table Kuniyuki Iwashima
2022-07-06 5:21 ` [PATCH v1 net 01/16] sysctl: Clean up proc_handler definitions Kuniyuki Iwashima
2022-07-06 5:21 ` [PATCH v1 net 02/16] sysctl: Add proc_dobool_lockless() Kuniyuki Iwashima
2022-07-06 5:21 ` [PATCH v1 net 03/16] sysctl: Add proc_dointvec_lockless() Kuniyuki Iwashima
2022-07-06 7:00 ` Eric Dumazet
2022-07-06 16:15 ` Kuniyuki Iwashima
2022-07-06 5:21 ` [PATCH v1 net 04/16] sysctl: Add proc_douintvec_lockless() Kuniyuki Iwashima
2022-07-06 5:21 ` Kuniyuki Iwashima [this message]
2022-07-06 5:21 ` [PATCH v1 net 06/16] sysctl: Add proc_douintvec_minmax_lockless() Kuniyuki Iwashima
2022-07-06 5:21 ` [PATCH v1 net 07/16] sysctl: Add proc_doulongvec_minmax_lockless() Kuniyuki Iwashima
2022-07-06 5:21 ` [PATCH v1 net 08/16] sysctl: Add proc_dointvec_jiffies_lockless() Kuniyuki Iwashima
2022-07-06 5:21 ` [PATCH v1 net 09/16] tcp: Fix a data-race around sysctl_tcp_max_orphans Kuniyuki Iwashima
2022-07-06 5:21 ` [PATCH v1 net 10/16] inetpeer: Fix data-races around sysctl Kuniyuki Iwashima
2022-07-06 5:21 ` [PATCH v1 net 11/16] net: Fix a data-race around sysctl_mem Kuniyuki Iwashima
2022-07-06 13:17 ` Steven Rostedt
2022-07-06 13:27 ` Steven Rostedt
2022-07-06 16:27 ` Kuniyuki Iwashima
2022-07-06 5:21 ` [PATCH v1 net 12/16] tcp: Mark sysctl_tcp_low_latency obsolete Kuniyuki Iwashima
2022-07-06 5:21 ` [PATCH v1 net 13/16] cipso: Fix a data-race around cipso_v4_cache_bucketsize Kuniyuki Iwashima
2022-07-06 5:21 ` [PATCH v1 net 14/16] cipso: Fix data-races around boolean sysctl Kuniyuki Iwashima
2022-07-06 5:21 ` [PATCH v1 net 15/16] icmp: Fix data-races around sysctl Kuniyuki Iwashima
2022-07-06 5:21 ` [PATCH v1 net 16/16] ipv4: Fix a data-race around sysctl_fib_sync_mem Kuniyuki Iwashima
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