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sctp: avoid auth_enable sysctl UAF during netns teardown

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proc_sctp_do_auth() updates the SCTP control socket after changing
net.sctp.auth_enable. The handler gets the per-net SCTP state from
ctl->data, so an already opened sysctl file can still target a network
namespace while that namespace is being torn down.

SCTP previously registered its per-net sysctls from sctp_defaults_init(),
while the control socket is created later from sctp_ctrlsock_init(). This
exposed a window during initialization where auth_enable was writable
before net->sctp.ctl_sock existed, and a teardown window where auth_enable
stayed writable after inet_ctl_sock_destroy() had released the control
socket.

Move the per-net SCTP sysctl registration into sctp_ctrlsock_init() after
sctp_ctl_sock_init() succeeds, and unregister the sysctl table before
destroying the control socket in sctp_ctrlsock_exit(). If sysctl
registration fails after the control socket was created, destroy the
control socket in the same init path.

Make sctp_sysctl_net_unregister() tolerate a missing header and clear the
saved pointer so init-error and exit paths can safely share the unregister
helper.

Fixes: 15649fd541 ("sctp: sysctl: auth_enable: avoid using current->nsproxy")
Cc: stable@vger.kernel.org
Reported-by: Yuan Tan <yuantan098@gmail.com>
Reported-by: Yifan Wu <yifanwucs@gmail.com>
Reported-by: Juefei Pu <tomapufckgml@gmail.com>
Reported-by: Xin Liu <bird@lzu.edu.cn>
Co-developed-by: Qi Tang <tpluszz77@gmail.com>
Signed-off-by: Qi Tang <tpluszz77@gmail.com>
Signed-off-by: Zhiling Zou <roxy520tt@gmail.com>
Signed-off-by: Ren Wei <n05ec@lzu.edu.cn>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/390cd5e91ed60eea27b0b64d0468301a9e73b808.1784033357.git.roxy520tt@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Zhiling Zou 2026-07-15 09:50:10 +08:00 committed by Jakub Kicinski
parent 18ae07691d
commit f8d5e78460
2 changed files with 19 additions and 10 deletions
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20
net/sctp/protocol.c
View File

@ -1383,10 +1383,6 @@ static int __net_init sctp_defaults_init(struct net *net)
net->sctp.l3mdev_accept = 1;
#endif
status = sctp_sysctl_net_register(net);
if (status)
goto err_sysctl_register;
/* Allocate and initialise sctp mibs. */
status = init_sctp_mibs(net);
if (status)
@ -1420,8 +1416,6 @@ static int __net_init sctp_defaults_init(struct net *net)
cleanup_sctp_mibs(net);
#endif
err_init_mibs:
sctp_sysctl_net_unregister(net);
err_sysctl_register:
return status;
}
@ -1436,7 +1430,6 @@ static void __net_exit sctp_defaults_exit(struct net *net)
net->sctp.proc_net_sctp = NULL;
#endif
cleanup_sctp_mibs(net);
sctp_sysctl_net_unregister(net);
}
static struct pernet_operations sctp_defaults_ops = {
@ -1450,16 +1443,27 @@ static int __net_init sctp_ctrlsock_init(struct net *net)
/* Initialize the control inode/socket for handling OOTB packets. */
status = sctp_ctl_sock_init(net);
if (status)
if (status) {
pr_err("Failed to initialize the SCTP control sock\n");
return status;
}
status = sctp_sysctl_net_register(net);
if (status) {
inet_ctl_sock_destroy(net->sctp.ctl_sock);
net->sctp.ctl_sock = NULL;
}
return status;
}
static void __net_exit sctp_ctrlsock_exit(struct net *net)
{
sctp_sysctl_net_unregister(net);
/* Free the control endpoint. */
inet_ctl_sock_destroy(net->sctp.ctl_sock);
net->sctp.ctl_sock = NULL;
}
static struct pernet_operations sctp_ctrlsock_ops = {

9
net/sctp/sysctl.c
View File

@ -615,11 +615,16 @@ int sctp_sysctl_net_register(struct net *net)
void sctp_sysctl_net_unregister(struct net *net)
{
struct ctl_table_header *header = net->sctp.sysctl_header;
const struct ctl_table *table;
table = net->sctp.sysctl_header->ctl_table_arg;
unregister_net_sysctl_table(net->sctp.sysctl_header);
if (!header)
return;
table = header->ctl_table_arg;
unregister_net_sysctl_table(header);
kfree(table);
net->sctp.sysctl_header = NULL;
}
static struct ctl_table_header *sctp_sysctl_header;