The following sysctl are global and can't be read from a netns:
net.core.rmem_default net.core.rmem_max net.core.wmem_default net.core.wmem_max
Make the following sysctl parameters available readonly from within a network namespace, allowing a container to read them.
Signed-off-by: Matteo Croce teknoraver@meta.com --- net/core/sysctl_net_core.c | 75 +++++++++++++++++++++----------------- 1 file changed, 42 insertions(+), 33 deletions(-)
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c index c9fb9ad87485..2079000691e2 100644 --- a/net/core/sysctl_net_core.c +++ b/net/core/sysctl_net_core.c @@ -382,38 +382,6 @@ proc_dolongvec_minmax_bpf_restricted(struct ctl_table *table, int write, #endif
static struct ctl_table net_core_table[] = { - { - .procname = "wmem_max", - .data = &sysctl_wmem_max, - .maxlen = sizeof(int), - .mode = 0644, - .proc_handler = proc_dointvec_minmax, - .extra1 = &min_sndbuf, - }, - { - .procname = "rmem_max", - .data = &sysctl_rmem_max, - .maxlen = sizeof(int), - .mode = 0644, - .proc_handler = proc_dointvec_minmax, - .extra1 = &min_rcvbuf, - }, - { - .procname = "wmem_default", - .data = &sysctl_wmem_default, - .maxlen = sizeof(int), - .mode = 0644, - .proc_handler = proc_dointvec_minmax, - .extra1 = &min_sndbuf, - }, - { - .procname = "rmem_default", - .data = &sysctl_rmem_default, - .maxlen = sizeof(int), - .mode = 0644, - .proc_handler = proc_dointvec_minmax, - .extra1 = &min_rcvbuf, - }, { .procname = "mem_pcpu_rsv", .data = &net_hotdata.sysctl_mem_pcpu_rsv, @@ -697,6 +665,41 @@ static struct ctl_table netns_core_table[] = { .extra2 = SYSCTL_ONE, .proc_handler = proc_dou8vec_minmax, }, + /* sysctl_core_net_init() will set the values after this + * to readonly in network namespaces + */ + { + .procname = "wmem_max", + .data = &sysctl_wmem_max, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &min_sndbuf, + }, + { + .procname = "rmem_max", + .data = &sysctl_rmem_max, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &min_rcvbuf, + }, + { + .procname = "wmem_default", + .data = &sysctl_wmem_default, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &min_sndbuf, + }, + { + .procname = "rmem_default", + .data = &sysctl_rmem_default, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &min_rcvbuf, + }, };
static int __init fb_tunnels_only_for_init_net_sysctl_setup(char *str) @@ -724,8 +727,14 @@ static __net_init int sysctl_core_net_init(struct net *net) if (tbl == NULL) goto err_dup;
- for (i = 0; i < table_size; ++i) + for (i = 0; i < table_size; ++i) { + if (tbl[i].data == &sysctl_wmem_max) + break; + tbl[i].data += (char *)net - (char *)&init_net; + } + for (; i < table_size; ++i) + tbl[i].mode &= ~0222; }
net->core.sysctl_hdr = register_net_sysctl_sz(net, "net/core", tbl, table_size);