From: Firo Yang firo.yang@suse.com
[ Upstream commit da05cecc4939c0410d56c29e252998b192756318 ]
Recently, a customer reported that from their container whose net namespace is different to the host's init_net, they can't set the container's net.sctp.rto_max to any value smaller than init_net.sctp.rto_min.
For instance, Host: sudo sysctl net.sctp.rto_min net.sctp.rto_min = 1000
Container: echo 100 > /mnt/proc-net/sctp/rto_min echo 400 > /mnt/proc-net/sctp/rto_max echo: write error: Invalid argument
This is caused by the check made from this'commit 4f3fdf3bc59c ("sctp: add check rto_min and rto_max in sysctl")' When validating the input value, it's always referring the boundary value set for the init_net namespace.
Having container's rto_max smaller than host's init_net.sctp.rto_min does make sense. Consider that the rto between two containers on the same host is very likely smaller than it for two hosts.
So to fix this problem, as suggested by Marcelo, this patch makes the extra pointers of rto_min, rto_max, pf_retrans, and ps_retrans point to the corresponding variables from the newly created net namespace while the new net namespace is being registered in sctp_sysctl_net_register.
Fixes: 4f3fdf3bc59c ("sctp: add check rto_min and rto_max in sysctl") Reviewed-by: Marcelo Ricardo Leitner marcelo.leitner@gmail.com Reviewed-by: Jakub Kicinski kuba@kernel.org Acked-by: Marcelo Ricardo Leitner marcelo.leitner@gmail.com Signed-off-by: Firo Yang firo.yang@suse.com Link: https://lore.kernel.org/r/20221209054854.23889-1-firo.yang@suse.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/sctp/sysctl.c | 73 ++++++++++++++++++++++++++++------------------- 1 file changed, 44 insertions(+), 29 deletions(-)
diff --git a/net/sctp/sysctl.c b/net/sctp/sysctl.c index c16c80963e55..e4af050aec1b 100644 --- a/net/sctp/sysctl.c +++ b/net/sctp/sysctl.c @@ -79,17 +79,18 @@ static struct ctl_table sctp_table[] = { { /* sentinel */ } };
+/* The following index defines are used in sctp_sysctl_net_register(). + * If you add new items to the sctp_net_table, please ensure that + * the index values of these defines hold the same meaning indicated by + * their macro names when they appear in sctp_net_table. + */ +#define SCTP_RTO_MIN_IDX 0 +#define SCTP_RTO_MAX_IDX 1 +#define SCTP_PF_RETRANS_IDX 2 +#define SCTP_PS_RETRANS_IDX 3 + static struct ctl_table sctp_net_table[] = { - { - .procname = "rto_initial", - .data = &init_net.sctp.rto_initial, - .maxlen = sizeof(unsigned int), - .mode = 0644, - .proc_handler = proc_dointvec_minmax, - .extra1 = SYSCTL_ONE, - .extra2 = &timer_max - }, - { + [SCTP_RTO_MIN_IDX] = { .procname = "rto_min", .data = &init_net.sctp.rto_min, .maxlen = sizeof(unsigned int), @@ -98,7 +99,7 @@ static struct ctl_table sctp_net_table[] = { .extra1 = SYSCTL_ONE, .extra2 = &init_net.sctp.rto_max }, - { + [SCTP_RTO_MAX_IDX] = { .procname = "rto_max", .data = &init_net.sctp.rto_max, .maxlen = sizeof(unsigned int), @@ -107,6 +108,33 @@ static struct ctl_table sctp_net_table[] = { .extra1 = &init_net.sctp.rto_min, .extra2 = &timer_max }, + [SCTP_PF_RETRANS_IDX] = { + .procname = "pf_retrans", + .data = &init_net.sctp.pf_retrans, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO, + .extra2 = &init_net.sctp.ps_retrans, + }, + [SCTP_PS_RETRANS_IDX] = { + .procname = "ps_retrans", + .data = &init_net.sctp.ps_retrans, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &init_net.sctp.pf_retrans, + .extra2 = &ps_retrans_max, + }, + { + .procname = "rto_initial", + .data = &init_net.sctp.rto_initial, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ONE, + .extra2 = &timer_max + }, { .procname = "rto_alpha_exp_divisor", .data = &init_net.sctp.rto_alpha, @@ -202,24 +230,6 @@ static struct ctl_table sctp_net_table[] = { .extra1 = SYSCTL_ONE, .extra2 = SYSCTL_INT_MAX, }, - { - .procname = "pf_retrans", - .data = &init_net.sctp.pf_retrans, - .maxlen = sizeof(int), - .mode = 0644, - .proc_handler = proc_dointvec_minmax, - .extra1 = SYSCTL_ZERO, - .extra2 = &init_net.sctp.ps_retrans, - }, - { - .procname = "ps_retrans", - .data = &init_net.sctp.ps_retrans, - .maxlen = sizeof(int), - .mode = 0644, - .proc_handler = proc_dointvec_minmax, - .extra1 = &init_net.sctp.pf_retrans, - .extra2 = &ps_retrans_max, - }, { .procname = "sndbuf_policy", .data = &init_net.sctp.sndbuf_policy, @@ -489,6 +499,11 @@ int sctp_sysctl_net_register(struct net *net) for (i = 0; table[i].data; i++) table[i].data += (char *)(&net->sctp) - (char *)&init_net.sctp;
+ table[SCTP_RTO_MIN_IDX].extra2 = &net->sctp.rto_max; + table[SCTP_RTO_MAX_IDX].extra1 = &net->sctp.rto_min; + table[SCTP_PF_RETRANS_IDX].extra2 = &net->sctp.ps_retrans; + table[SCTP_PS_RETRANS_IDX].extra1 = &net->sctp.pf_retrans; + net->sctp.sysctl_header = register_net_sysctl(net, "net/sctp", table); if (net->sctp.sysctl_header == NULL) { kfree(table);