diff mbox series

[net,9/9] rds: sysctl: rds_tcp_{rcv,snd}buf: avoid using current->nsproxy

Message ID 20250108-net-sysctl-current-nsproxy-v1-9-5df34b2083e8@kernel.org (mailing list archive)
State New
Delegated to: Netdev Maintainers
Headers show
Series net: sysctl: avoid using current->nsproxy | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1 this patch: 1
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 9 of 9 maintainers
netdev/build_clang success Errors and warnings before: 2 this patch: 2
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 1 this patch: 1
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 75 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest fail net-next-2025-01-08--18-00 (tests: 883)

Commit Message

Matthieu Baerts Jan. 8, 2025, 3:34 p.m. UTC
As mentioned in a previous commit of this series, using the 'net'
structure via 'current' is not recommended for different reasons:

- Inconsistency: getting info from the reader's/writer's netns vs only
  from the opener's netns.

- current->nsproxy can be NULL in some cases, resulting in an 'Oops'
  (null-ptr-deref), e.g. when the current task is exiting, as spotted by
  syzbot [1] using acct(2).

The per-netns structure can be obtained from the table->data using
container_of(), then the 'net' one can be retrieved from the listen
socket (if available).

Fixes: c6a58ffed536 ("RDS: TCP: Add sysctl tunables for sndbuf/rcvbuf on rds-tcp socket")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/67769ecb.050a0220.3a8527.003f.GAE@google.com [1]
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 net/rds/tcp.c | 39 ++++++++++++++++++++++++++++++++-------
 1 file changed, 32 insertions(+), 7 deletions(-)
diff mbox series

Patch

diff --git a/net/rds/tcp.c b/net/rds/tcp.c
index 351ac1747224a3a1c8b0e297ba53cdbbcbc55401..0581c53e6517043ad6c2ad4207b26ab169989ed8 100644
--- a/net/rds/tcp.c
+++ b/net/rds/tcp.c
@@ -61,8 +61,10 @@  static atomic_t rds_tcp_unloading = ATOMIC_INIT(0);
 
 static struct kmem_cache *rds_tcp_conn_slab;
 
-static int rds_tcp_skbuf_handler(const struct ctl_table *ctl, int write,
-				 void *buffer, size_t *lenp, loff_t *fpos);
+static int rds_tcp_sndbuf_handler(const struct ctl_table *ctl, int write,
+				  void *buffer, size_t *lenp, loff_t *fpos);
+static int rds_tcp_rcvbuf_handler(const struct ctl_table *ctl, int write,
+				  void *buffer, size_t *lenp, loff_t *fpos);
 
 static int rds_tcp_min_sndbuf = SOCK_MIN_SNDBUF;
 static int rds_tcp_min_rcvbuf = SOCK_MIN_RCVBUF;
@@ -74,7 +76,7 @@  static struct ctl_table rds_tcp_sysctl_table[] = {
 		/* data is per-net pointer */
 		.maxlen         = sizeof(int),
 		.mode           = 0644,
-		.proc_handler   = rds_tcp_skbuf_handler,
+		.proc_handler   = rds_tcp_sndbuf_handler,
 		.extra1		= &rds_tcp_min_sndbuf,
 	},
 #define	RDS_TCP_RCVBUF	1
@@ -83,7 +85,7 @@  static struct ctl_table rds_tcp_sysctl_table[] = {
 		/* data is per-net pointer */
 		.maxlen         = sizeof(int),
 		.mode           = 0644,
-		.proc_handler   = rds_tcp_skbuf_handler,
+		.proc_handler   = rds_tcp_rcvbuf_handler,
 		.extra1		= &rds_tcp_min_rcvbuf,
 	},
 };
@@ -682,10 +684,10 @@  static void rds_tcp_sysctl_reset(struct net *net)
 	spin_unlock_irq(&rds_tcp_conn_lock);
 }
 
-static int rds_tcp_skbuf_handler(const struct ctl_table *ctl, int write,
+static int rds_tcp_skbuf_handler(struct rds_tcp_net *rtn,
+				 const struct ctl_table *ctl, int write,
 				 void *buffer, size_t *lenp, loff_t *fpos)
 {
-	struct net *net = current->nsproxy->net_ns;
 	int err;
 
 	err = proc_dointvec_minmax(ctl, write, buffer, lenp, fpos);
@@ -694,11 +696,34 @@  static int rds_tcp_skbuf_handler(const struct ctl_table *ctl, int write,
 			*(int *)(ctl->extra1));
 		return err;
 	}
-	if (write)
+
+	if (write && rtn->rds_tcp_listen_sock && rtn->rds_tcp_listen_sock->sk) {
+		struct net *net = sock_net(rtn->rds_tcp_listen_sock->sk);
+
 		rds_tcp_sysctl_reset(net);
+	}
+
 	return 0;
 }
 
+static int rds_tcp_sndbuf_handler(const struct ctl_table *ctl, int write,
+				  void *buffer, size_t *lenp, loff_t *fpos)
+{
+	struct rds_tcp_net *rtn = container_of(ctl->data, struct rds_tcp_net,
+					       sndbuf_size);
+
+	return rds_tcp_skbuf_handler(rtn, ctl, write, buffer, lenp, fpos);
+}
+
+static int rds_tcp_rcvbuf_handler(const struct ctl_table *ctl, int write,
+				  void *buffer, size_t *lenp, loff_t *fpos)
+{
+	struct rds_tcp_net *rtn = container_of(ctl->data, struct rds_tcp_net,
+					       rcvbuf_size);
+
+	return rds_tcp_skbuf_handler(rtn, ctl, write, buffer, lenp, fpos);
+}
+
 static void rds_tcp_exit(void)
 {
 	rds_tcp_set_unloading();