[PATCH v2 net 00/12] sysctl: Fix data-races around ipv4_table.

[PATCH v2 net 00/12] sysctl: Fix data-races around ipv4_table.

[Kuniyuki Iwashima]

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.

The first half of this series changes some proc handlers used in ipv4_table
to use READ_ONCE() and WRITE_ONCE() internally to fix data-races on the
sysctl side.  Then, the second half adds READ_ONCE() to the other readers
of ipv4_table.


Changes:
  v2:
    * Drop some changes that makes backporting difficult
      * First cleanup patch
      * Lockless helpers and .proc_handler changes
    * Drop the tracing part for .sysctl_mem
      * Steve already posted a fix
    * Drop int-to-bool change for cipso
      * Should be posted to net-next later
    * Drop proc_dobool() change
      * Can be included in another series

  v1: https://lore.kernel.org/netdev/20220706052130.16368-1-kuniyu@amazon.com/


Kuniyuki Iwashima (12):
  sysctl: Fix data races in proc_dointvec().
  sysctl: Fix data races in proc_douintvec().
  sysctl: Fix data races in proc_dointvec_minmax().
  sysctl: Fix data races in proc_douintvec_minmax().
  sysctl: Fix data races in proc_doulongvec_minmax().
  sysctl: Fix data races in proc_dointvec_jiffies().
  tcp: Fix a data-race around sysctl_tcp_max_orphans.
  inetpeer: Fix data-races around sysctl.
  net: Fix data-races around sysctl_mem.
  cipso: Fix data-races around sysctl.
  icmp: Fix data-races around sysctl.
  ipv4: Fix a data-race around sysctl_fib_sync_mem.

 Documentation/networking/ip-sysctl.rst |  2 +-
 include/net/sock.h                     |  2 +-
 kernel/sysctl.c                        | 25 ++++++++++++++-----------
 net/ipv4/cipso_ipv4.c                  | 12 +++++++-----
 net/ipv4/fib_trie.c                    |  2 +-
 net/ipv4/icmp.c                        |  5 +++--
 net/ipv4/inetpeer.c                    | 12 ++++++++----
 net/ipv4/tcp.c                         |  3 ++-
 8 files changed, 37 insertions(+), 26 deletions(-)

-- 
2.30.2

[PATCH v2 net 01/12] sysctl: Fix data races in proc_dointvec().

[Kuniyuki Iwashima]

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() to use READ_ONCE() and WRITE_ONCE()
internally to fix data-races on the sysctl side.  For now, proc_dointvec()
itself is tolerant to a data-race, but we still need to add annotations on
the other subsystem's side.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 kernel/sysctl.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index e52b6e372c60..c8a05655ae60 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -446,14 +446,14 @@ static int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp,
 		if (*negp) {
 			if (*lvalp > (unsigned long) INT_MAX + 1)
 				return -EINVAL;
-			*valp = -*lvalp;
+			WRITE_ONCE(*valp, -*lvalp);
 		} else {
 			if (*lvalp > (unsigned long) INT_MAX)
 				return -EINVAL;
-			*valp = *lvalp;
+			WRITE_ONCE(*valp, *lvalp);
 		}
 	} else {
-		int val = *valp;
+		int val = READ_ONCE(*valp);
 		if (val < 0) {
 			*negp = true;
 			*lvalp = -(unsigned long)val;
-- 
2.30.2

[PATCH v2 net 02/12] sysctl: Fix data races in proc_douintvec().

[Kuniyuki Iwashima]

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_douintvec() to use READ_ONCE() and WRITE_ONCE()
internally to fix data-races on the sysctl side.  For now, proc_douintvec()
itself is tolerant to a data-race, but we still need to add annotations on
the other subsystem's side.

Fixes: e7d316a02f68 ("sysctl: handle error writing UINT_MAX to u32 fields")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
CC: Subash Abhinov Kasiviswanathan <quic_subashab@quicinc.com>
---
 kernel/sysctl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index c8a05655ae60..2ab8c2a37e8f 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -472,9 +472,9 @@ static int do_proc_douintvec_conv(unsigned long *lvalp,
 	if (write) {
 		if (*lvalp > UINT_MAX)
 			return -EINVAL;
-		*valp = *lvalp;
+		WRITE_ONCE(*valp, *lvalp);
 	} else {
-		unsigned int val = *valp;
+		unsigned int val = READ_ONCE(*valp);
 		*lvalp = (unsigned long)val;
 	}
 	return 0;
-- 
2.30.2

[PATCH v2 net 03/12] sysctl: Fix data races in proc_dointvec_minmax().

[Kuniyuki Iwashima]

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() and
WRITE_ONCE() internally to fix data-races 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.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 kernel/sysctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 2ab8c2a37e8f..4d87832367f2 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -857,7 +857,7 @@ 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;
-- 
2.30.2

[PATCH v2 net 04/12] sysctl: Fix data races in proc_douintvec_minmax().

[Kuniyuki Iwashima]

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_douintvec_minmax() to use READ_ONCE() and
WRITE_ONCE() internally to fix data-races on the sysctl side.  For now,
proc_douintvec_minmax() itself is tolerant to a data-race, but we still
need to add annotations on the other subsystem's side.

Fixes: 61d9b56a8920 ("sysctl: add unsigned int range support")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 kernel/sysctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 4d87832367f2..379721a03d41 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -923,7 +923,7 @@ static int do_proc_douintvec_minmax_conv(unsigned long *lvalp,
 		    (param->max && *param->max < tmp))
 			return -ERANGE;
 
-		*valp = tmp;
+		WRITE_ONCE(*valp, tmp);
 	}
 
 	return 0;
-- 
2.30.2

[PATCH v2 net 05/12] sysctl: Fix data races in proc_doulongvec_minmax().

[Kuniyuki Iwashima]

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_doulongvec_minmax() to use READ_ONCE() and
WRITE_ONCE() internally to fix data-races on the sysctl side.  For now,
proc_doulongvec_minmax() itself is tolerant to a data-race, but we still
need to add annotations on the other subsystem's side.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 kernel/sysctl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 379721a03d41..8c55ba01f41b 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1090,9 +1090,9 @@ static int __do_proc_doulongvec_minmax(void *data, struct ctl_table *table,
 				err = -EINVAL;
 				break;
 			}
-			*i = val;
+			WRITE_ONCE(*i, val);
 		} else {
-			val = convdiv * (*i) / convmul;
+			val = convdiv * READ_ONCE(*i) / convmul;
 			if (!first)
 				proc_put_char(&buffer, &left, '\t');
 			proc_put_long(&buffer, &left, val, false);
-- 
2.30.2

[PATCH v2 net 06/12] sysctl: Fix data races in proc_dointvec_jiffies().

[Kuniyuki Iwashima]

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_jiffies() to use READ_ONCE() and
WRITE_ONCE() internally to fix data-races on the sysctl side.  For now,
proc_dointvec_jiffies() itself is tolerant to a data-race, but we still
need to add annotations on the other subsystem's side.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 kernel/sysctl.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 8c55ba01f41b..bf9383d17e1b 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1173,9 +1173,12 @@ static int do_proc_dointvec_jiffies_conv(bool *negp, unsigned long *lvalp,
 	if (write) {
 		if (*lvalp > INT_MAX / HZ)
 			return 1;
-		*valp = *negp ? -(*lvalp*HZ) : (*lvalp*HZ);
+		if (*negp)
+			WRITE_ONCE(*valp, -*lvalp * HZ);
+		else
+			WRITE_ONCE(*valp, *lvalp * HZ);
 	} else {
-		int val = *valp;
+		int val = READ_ONCE(*valp);
 		unsigned long lval;
 		if (val < 0) {
 			*negp = true;
-- 
2.30.2

[PATCH v2 net 07/12] tcp: Fix a data-race around sysctl_tcp_max_orphans.

[Kuniyuki Iwashima]

While reading sysctl_tcp_max_orphans, it can be changed concurrently.
So, we need to add READ_ONCE() to avoid a data-race.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 net/ipv4/tcp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 028513d3e2a2..2222dfdde316 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2715,7 +2715,8 @@ static void tcp_orphan_update(struct timer_list *unused)
 
 static bool tcp_too_many_orphans(int shift)
 {
-	return READ_ONCE(tcp_orphan_cache) << shift > sysctl_tcp_max_orphans;
+	return READ_ONCE(tcp_orphan_cache) << shift >
+		READ_ONCE(sysctl_tcp_max_orphans);
 }
 
 bool tcp_check_oom(struct sock *sk, int shift)
-- 
2.30.2

[PATCH v2 net 08/12] inetpeer: Fix data-races around sysctl.

[Kuniyuki Iwashima]

While reading inetpeer sysctl variables, they can be changed
concurrently.  So, we need to add READ_ONCE() to avoid data-races.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 net/ipv4/inetpeer.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c
index da21dfce24d7..e9fed83e9b3c 100644
--- a/net/ipv4/inetpeer.c
+++ b/net/ipv4/inetpeer.c
@@ -141,16 +141,20 @@ static void inet_peer_gc(struct inet_peer_base *base,
 			 struct inet_peer *gc_stack[],
 			 unsigned int gc_cnt)
 {
+	int peer_threshold, peer_maxttl, peer_minttl;
 	struct inet_peer *p;
 	__u32 delta, ttl;
 	int i;
 
-	if (base->total >= inet_peer_threshold)
+	peer_threshold = READ_ONCE(inet_peer_threshold);
+	peer_maxttl = READ_ONCE(inet_peer_maxttl);
+	peer_minttl = READ_ONCE(inet_peer_minttl);
+
+	if (base->total >= peer_threshold)
 		ttl = 0; /* be aggressive */
 	else
-		ttl = inet_peer_maxttl
-				- (inet_peer_maxttl - inet_peer_minttl) / HZ *
-					base->total / inet_peer_threshold * HZ;
+		ttl = peer_maxttl - (peer_maxttl - peer_minttl) / HZ *
+			base->total / peer_threshold * HZ;
 	for (i = 0; i < gc_cnt; i++) {
 		p = gc_stack[i];
 
-- 
2.30.2

[PATCH v2 net 09/12] net: Fix data-races around sysctl_mem.

[Kuniyuki Iwashima]

While reading .sysctl_mem, it can be changed concurrently.
So, we need to add READ_ONCE() to avoid data-races.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 include/net/sock.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 72ca97ccb460..9fa54762e077 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1529,7 +1529,7 @@ void __sk_mem_reclaim(struct sock *sk, int amount);
 /* sysctl_mem values are in pages, we convert them in SK_MEM_QUANTUM units */
 static inline long sk_prot_mem_limits(const struct sock *sk, int index)
 {
-	long val = sk->sk_prot->sysctl_mem[index];
+	long val = READ_ONCE(sk->sk_prot->sysctl_mem[index]);
 
 #if PAGE_SIZE > SK_MEM_QUANTUM
 	val <<= PAGE_SHIFT - SK_MEM_QUANTUM_SHIFT;
-- 
2.30.2

Re: [PATCH v2 net 09/12] net: Fix data-races around sysctl_mem.

[Matthieu Baerts]

[-- Attachment #1: Type: text/plain, Size: 782 bytes --]

Hello,

On 07/07/2022 01:40, Kuniyuki Iwashima wrote:
> While reading .sysctl_mem, it can be changed concurrently.
> So, we need to add READ_ONCE() to avoid data-races.

FYI, we got a small conflict when merging -net in net-next in the MPTCP
tree due to this patch applied in -net:

  310731e2f161 ("net: Fix data-races around sysctl_mem.")

and this one from net-next:

  e70f3c701276 ("Revert "net: set SK_MEM_QUANTUM to 4096"")

The conflict has been resolved on our side[1] and the resolution we
suggest is attached to this email.

I'm sharing this thinking it can help others but if it only creates
noise, please tell me! :)

Cheers,
Matt

[1] https://github.com/multipath-tcp/mptcp_net-next/commit/b01bda9d0fe6
-- 
Tessares | Belgium | Hybrid Access Solutions
www.tessares.net

[-- Attachment #2: b01bda9d0fe6.patch --]
[-- Type: text/x-patch, Size: 836 bytes --]

diff --cc include/net/sock.h
index 0dd43c3df49b,9fa54762e077..f7ad1a7705e9
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@@ -1541,10 -1521,22 +1541,10 @@@ void __sk_mem_reclaim(struct sock *sk, 
  #define SK_MEM_SEND	0
  #define SK_MEM_RECV	1
  
 -/* sysctl_mem values are in pages, we convert them in SK_MEM_QUANTUM units */
 +/* sysctl_mem values are in pages */
  static inline long sk_prot_mem_limits(const struct sock *sk, int index)
  {
- 	return sk->sk_prot->sysctl_mem[index];
 -	long val = READ_ONCE(sk->sk_prot->sysctl_mem[index]);
 -
 -#if PAGE_SIZE > SK_MEM_QUANTUM
 -	val <<= PAGE_SHIFT - SK_MEM_QUANTUM_SHIFT;
 -#elif PAGE_SIZE < SK_MEM_QUANTUM
 -	val >>= SK_MEM_QUANTUM_SHIFT - PAGE_SHIFT;
 -#endif
 -	return val;
++	return READ_ONCE(sk->sk_prot->sysctl_mem[index]);
  }
  
  static inline int sk_mem_pages(int amt)

[PATCH v2 net 10/12] cipso: Fix data-races around sysctl.

[Kuniyuki Iwashima]

While reading cipso sysctl variables, they can be changed concurrently.
So, we need to add READ_ONCE() to avoid data-races.

Fixes: 446fda4f2682 ("[NetLabel]: CIPSOv4 engine")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
CC: Paul Moore <paul@paul-moore.com>
---
 Documentation/networking/ip-sysctl.rst |  2 +-
 net/ipv4/cipso_ipv4.c                  | 12 +++++++-----
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index 9f41961d11d5..0e58001f8580 100644
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst
@@ -1085,7 +1085,7 @@ cipso_cache_enable - BOOLEAN
 cipso_cache_bucket_size - INTEGER
 	The CIPSO label cache consists of a fixed size hash table with each
 	hash bucket containing a number of cache entries.  This variable limits
-	the number of entries in each hash bucket; the larger the value the
+	the number of entries in each hash bucket; the larger the value is, the
 	more CIPSO label mappings that can be cached.  When the number of
 	entries in a given hash bucket reaches this limit adding new entries
 	causes the oldest entry in the bucket to be removed to make room.
diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index 62d5f99760aa..6cd3b6c559f0 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -239,7 +239,7 @@ static int cipso_v4_cache_check(const unsigned char *key,
 	struct cipso_v4_map_cache_entry *prev_entry = NULL;
 	u32 hash;
 
-	if (!cipso_v4_cache_enabled)
+	if (!READ_ONCE(cipso_v4_cache_enabled))
 		return -ENOENT;
 
 	hash = cipso_v4_map_cache_hash(key, key_len);
@@ -296,13 +296,14 @@ static int cipso_v4_cache_check(const unsigned char *key,
 int cipso_v4_cache_add(const unsigned char *cipso_ptr,
 		       const struct netlbl_lsm_secattr *secattr)
 {
+	int bkt_size = READ_ONCE(cipso_v4_cache_bucketsize);
 	int ret_val = -EPERM;
 	u32 bkt;
 	struct cipso_v4_map_cache_entry *entry = NULL;
 	struct cipso_v4_map_cache_entry *old_entry = NULL;
 	u32 cipso_ptr_len;
 
-	if (!cipso_v4_cache_enabled || cipso_v4_cache_bucketsize <= 0)
+	if (!READ_ONCE(cipso_v4_cache_enabled) || bkt_size <= 0)
 		return 0;
 
 	cipso_ptr_len = cipso_ptr[1];
@@ -322,7 +323,7 @@ int cipso_v4_cache_add(const unsigned char *cipso_ptr,
 
 	bkt = entry->hash & (CIPSO_V4_CACHE_BUCKETS - 1);
 	spin_lock_bh(&cipso_v4_cache[bkt].lock);
-	if (cipso_v4_cache[bkt].size < cipso_v4_cache_bucketsize) {
+	if (cipso_v4_cache[bkt].size < bkt_size) {
 		list_add(&entry->list, &cipso_v4_cache[bkt].list);
 		cipso_v4_cache[bkt].size += 1;
 	} else {
@@ -1199,7 +1200,8 @@ static int cipso_v4_gentag_rbm(const struct cipso_v4_doi *doi_def,
 		/* This will send packets using the "optimized" format when
 		 * possible as specified in  section 3.4.2.6 of the
 		 * CIPSO draft. */
-		if (cipso_v4_rbm_optfmt && ret_val > 0 && ret_val <= 10)
+		if (READ_ONCE(cipso_v4_rbm_optfmt) && ret_val > 0 &&
+		    ret_val <= 10)
 			tag_len = 14;
 		else
 			tag_len = 4 + ret_val;
@@ -1603,7 +1605,7 @@ int cipso_v4_validate(const struct sk_buff *skb, unsigned char **option)
 			 * all the CIPSO validations here but it doesn't
 			 * really specify _exactly_ what we need to validate
 			 * ... so, just make it a sysctl tunable. */
-			if (cipso_v4_rbm_strictvalid) {
+			if (READ_ONCE(cipso_v4_rbm_strictvalid)) {
 				if (cipso_v4_map_lvl_valid(doi_def,
 							   tag[3]) < 0) {
 					err_offset = opt_iter + 3;
-- 
2.30.2

Re: [PATCH v2 net 10/12] cipso: Fix data-races around sysctl.

[Paul Moore]

On Wed, Jul 6, 2022 at 7:43 PM Kuniyuki Iwashima <kuniyu@amazon.com> wrote:
>
> While reading cipso sysctl variables, they can be changed concurrently.
> So, we need to add READ_ONCE() to avoid data-races.
>
> Fixes: 446fda4f2682 ("[NetLabel]: CIPSOv4 engine")
> Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
> ---
> CC: Paul Moore <paul@paul-moore.com>

Thanks for the patch, this looks good to me.  However, in the future
you should probably drop the extra "---" separator (just leave the one
before the diffstat below) and move my "Cc:" up above "Fixes:".

Acked-by: Paul Moore <paul@paul-moore.com>

> ---
>  Documentation/networking/ip-sysctl.rst |  2 +-
>  net/ipv4/cipso_ipv4.c                  | 12 +++++++-----
>  2 files changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
> index 9f41961d11d5..0e58001f8580 100644
> --- a/Documentation/networking/ip-sysctl.rst
> +++ b/Documentation/networking/ip-sysctl.rst
> @@ -1085,7 +1085,7 @@ cipso_cache_enable - BOOLEAN
>  cipso_cache_bucket_size - INTEGER
>         The CIPSO label cache consists of a fixed size hash table with each
>         hash bucket containing a number of cache entries.  This variable limits
> -       the number of entries in each hash bucket; the larger the value the
> +       the number of entries in each hash bucket; the larger the value is, the
>         more CIPSO label mappings that can be cached.  When the number of
>         entries in a given hash bucket reaches this limit adding new entries
>         causes the oldest entry in the bucket to be removed to make room.
> diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
> index 62d5f99760aa..6cd3b6c559f0 100644
> --- a/net/ipv4/cipso_ipv4.c
> +++ b/net/ipv4/cipso_ipv4.c
> @@ -239,7 +239,7 @@ static int cipso_v4_cache_check(const unsigned char *key,
>         struct cipso_v4_map_cache_entry *prev_entry = NULL;
>         u32 hash;
>
> -       if (!cipso_v4_cache_enabled)
> +       if (!READ_ONCE(cipso_v4_cache_enabled))
>                 return -ENOENT;
>
>         hash = cipso_v4_map_cache_hash(key, key_len);
> @@ -296,13 +296,14 @@ static int cipso_v4_cache_check(const unsigned char *key,
>  int cipso_v4_cache_add(const unsigned char *cipso_ptr,
>                        const struct netlbl_lsm_secattr *secattr)
>  {
> +       int bkt_size = READ_ONCE(cipso_v4_cache_bucketsize);
>         int ret_val = -EPERM;
>         u32 bkt;
>         struct cipso_v4_map_cache_entry *entry = NULL;
>         struct cipso_v4_map_cache_entry *old_entry = NULL;
>         u32 cipso_ptr_len;
>
> -       if (!cipso_v4_cache_enabled || cipso_v4_cache_bucketsize <= 0)
> +       if (!READ_ONCE(cipso_v4_cache_enabled) || bkt_size <= 0)
>                 return 0;
>
>         cipso_ptr_len = cipso_ptr[1];
> @@ -322,7 +323,7 @@ int cipso_v4_cache_add(const unsigned char *cipso_ptr,
>
>         bkt = entry->hash & (CIPSO_V4_CACHE_BUCKETS - 1);
>         spin_lock_bh(&cipso_v4_cache[bkt].lock);
> -       if (cipso_v4_cache[bkt].size < cipso_v4_cache_bucketsize) {
> +       if (cipso_v4_cache[bkt].size < bkt_size) {
>                 list_add(&entry->list, &cipso_v4_cache[bkt].list);
>                 cipso_v4_cache[bkt].size += 1;
>         } else {
> @@ -1199,7 +1200,8 @@ static int cipso_v4_gentag_rbm(const struct cipso_v4_doi *doi_def,
>                 /* This will send packets using the "optimized" format when
>                  * possible as specified in  section 3.4.2.6 of the
>                  * CIPSO draft. */
> -               if (cipso_v4_rbm_optfmt && ret_val > 0 && ret_val <= 10)
> +               if (READ_ONCE(cipso_v4_rbm_optfmt) && ret_val > 0 &&
> +                   ret_val <= 10)
>                         tag_len = 14;
>                 else
>                         tag_len = 4 + ret_val;
> @@ -1603,7 +1605,7 @@ int cipso_v4_validate(const struct sk_buff *skb, unsigned char **option)
>                          * all the CIPSO validations here but it doesn't
>                          * really specify _exactly_ what we need to validate
>                          * ... so, just make it a sysctl tunable. */
> -                       if (cipso_v4_rbm_strictvalid) {
> +                       if (READ_ONCE(cipso_v4_rbm_strictvalid)) {
>                                 if (cipso_v4_map_lvl_valid(doi_def,
>                                                            tag[3]) < 0) {
>                                         err_offset = opt_iter + 3;
> --
> 2.30.2

-- 
paul-moore.com

Re: [PATCH v2 net 10/12] cipso: Fix data-races around sysctl.

[Kuniyuki Iwashima]

From:   Paul Moore <paul@paul-moore.com>
Date:   Thu, 7 Jul 2022 15:15:52 -0400
> On Wed, Jul 6, 2022 at 7:43 PM Kuniyuki Iwashima <kuniyu@amazon.com> wrote:
> >
> > While reading cipso sysctl variables, they can be changed concurrently.
> > So, we need to add READ_ONCE() to avoid data-races.
> >
> > Fixes: 446fda4f2682 ("[NetLabel]: CIPSOv4 engine")
> > Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
> > ---
> > CC: Paul Moore <paul@paul-moore.com>
> 
> Thanks for the patch, this looks good to me.  However, in the future
> you should probably drop the extra "---" separator (just leave the one
> before the diffstat below) and move my "Cc:" up above "Fixes:".
> 
> Acked-by: Paul Moore <paul@paul-moore.com>

I was wondering if both CC and Acked-by should stay in each commit, but
will do so in the next time.

Thank you for taking a look!

Re: [PATCH v2 net 10/12] cipso: Fix data-races around sysctl.

[Jakub Kicinski]

On Thu, 7 Jul 2022 15:15:37 -0700 Kuniyuki Iwashima wrote:
> I was wondering if both CC and Acked-by should stay in each commit, but
> will do so in the next time.

For Paul only, don't take that as general advice.

Re: [PATCH v2 net 10/12] cipso: Fix data-races around sysctl.

[Kuniyuki Iwashima]

From:   Jakub Kicinski <kuba@kernel.org>
Date:   Thu, 7 Jul 2022 17:24:24 -0700
> On Thu, 7 Jul 2022 15:15:37 -0700 Kuniyuki Iwashima wrote:
> > I was wondering if both CC and Acked-by should stay in each commit, but
> > will do so in the next time.
> 
> For Paul only, don't take that as general advice.

...got it, thanks :)

[PATCH v2 net 11/12] icmp: Fix data-races around sysctl.

[Kuniyuki Iwashima]

While reading icmp sysctl variables, they can be changed concurrently.
So, we need to add READ_ONCE() to avoid data-races.

Fixes: 4cdf507d5452 ("icmp: add a global rate limitation")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 net/ipv4/icmp.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index efea0e796f06..0f9e61d29f73 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -253,11 +253,12 @@ bool icmp_global_allow(void)
 	spin_lock(&icmp_global.lock);
 	delta = min_t(u32, now - icmp_global.stamp, HZ);
 	if (delta >= HZ / 50) {
-		incr = sysctl_icmp_msgs_per_sec * delta / HZ ;
+		incr = READ_ONCE(sysctl_icmp_msgs_per_sec) * delta / HZ;
 		if (incr)
 			WRITE_ONCE(icmp_global.stamp, now);
 	}
-	credit = min_t(u32, icmp_global.credit + incr, sysctl_icmp_msgs_burst);
+	credit = min_t(u32, icmp_global.credit + incr,
+		       READ_ONCE(sysctl_icmp_msgs_burst));
 	if (credit) {
 		/* We want to use a credit of one in average, but need to randomize
 		 * it for security reasons.
-- 
2.30.2

[PATCH v2 net 12/12] ipv4: Fix a data-race around sysctl_fib_sync_mem.

[Kuniyuki Iwashima]

While reading sysctl_fib_sync_mem, it can be changed concurrently.
So, we need to add READ_ONCE() to avoid a data-race.

Fixes: 9ab948a91b2c ("ipv4: Allow amount of dirty memory from fib resizing to be controllable")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
CC: David Ahern <dsahern@kernel.org>
---
 net/ipv4/fib_trie.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 2734c3af7e24..46e8a5125853 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -498,7 +498,7 @@ static void tnode_free(struct key_vector *tn)
 		tn = container_of(head, struct tnode, rcu)->kv;
 	}
 
-	if (tnode_free_size >= sysctl_fib_sync_mem) {
+	if (tnode_free_size >= READ_ONCE(sysctl_fib_sync_mem)) {
 		tnode_free_size = 0;
 		synchronize_rcu();
 	}
-- 
2.30.2

Re: [PATCH v2 net 00/12] sysctl: Fix data-races around ipv4_table.

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (master)
by David S. Miller <davem@davemloft.net>:

On Wed, 6 Jul 2022 16:39:51 -0700 you wrote:
> 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.
> 
> The first half of this series changes some proc handlers used in ipv4_table
> to use READ_ONCE() and WRITE_ONCE() internally to fix data-races on the
> sysctl side.  Then, the second half adds READ_ONCE() to the other readers
> of ipv4_table.
> 
> [...]

Here is the summary with links:
  - [v2,net,01/12] sysctl: Fix data races in proc_dointvec().
    https://git.kernel.org/netdev/net/c/1f1be04b4d48
  - [v2,net,02/12] sysctl: Fix data races in proc_douintvec().
    https://git.kernel.org/netdev/net/c/4762b532ec95
  - [v2,net,03/12] sysctl: Fix data races in proc_dointvec_minmax().
    https://git.kernel.org/netdev/net/c/f613d86d014b
  - [v2,net,04/12] sysctl: Fix data races in proc_douintvec_minmax().
    https://git.kernel.org/netdev/net/c/2d3b559df3ed
  - [v2,net,05/12] sysctl: Fix data races in proc_doulongvec_minmax().
    https://git.kernel.org/netdev/net/c/c31bcc8fb89f
  - [v2,net,06/12] sysctl: Fix data races in proc_dointvec_jiffies().
    https://git.kernel.org/netdev/net/c/e87782087766
  - [v2,net,07/12] tcp: Fix a data-race around sysctl_tcp_max_orphans.
    https://git.kernel.org/netdev/net/c/47e6ab24e8c6
  - [v2,net,08/12] inetpeer: Fix data-races around sysctl.
    https://git.kernel.org/netdev/net/c/3d32edf1f3c3
  - [v2,net,09/12] net: Fix data-races around sysctl_mem.
    https://git.kernel.org/netdev/net/c/310731e2f161
  - [v2,net,10/12] cipso: Fix data-races around sysctl.
    https://git.kernel.org/netdev/net/c/dd44f04b9214
  - [v2,net,11/12] icmp: Fix data-races around sysctl.
    https://git.kernel.org/netdev/net/c/48d7ee321ea5
  - [v2,net,12/12] ipv4: Fix a data-race around sysctl_fib_sync_mem.
    https://git.kernel.org/netdev/net/c/73318c4b7dbd

You are awesome, thank you!
-- 
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