diff mbox series

[net-next,1/2] net: make net.core.{r,w}mem_{default,max} namespaced

Message ID 20240528121139.38035-2-teknoraver@meta.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series net: visibility of memory limits in netns | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 904 this patch: 904
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers warning 2 maintainers not CCed: soheil@google.com dsahern@kernel.org
netdev/build_clang success Errors and warnings before: 906 this patch: 906
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 No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 908 this patch: 908
netdev/checkpatch warning WARNING: From:/Signed-off-by: email address mismatch: 'From: Matteo Croce <technoboy85@gmail.com>' != 'Signed-off-by: Matteo Croce <teknoraver@meta.com>'
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 success net-next-2024-05-30--06-00 (tests: 1042)

Commit Message

Matteo Croce May 28, 2024, 12:11 p.m. UTC 
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(-)

Comments

Shakeel Butt May 28, 2024, 3:02 p.m. UTC | #1 
On Tue, May 28, 2024 at 02:11:38PM GMT, Matteo Croce wrote:
> 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>

Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
diff mbox series

Patch

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);