path: root/net/sysctl_net.c
diff options
authorStephen Hemminger <shemminger@vyatta.com>2008-07-25 01:48:32 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-25 10:53:45 -0700
commit4ecb90090c84210a8bd2a9d7a5906e616735873c (patch)
treea7baec8859ff9750296be318400ba4475eb40b6c /net/sysctl_net.c
parent99541c23cd32bacf1a591ca537a7c0cb9053ad7e (diff)
sysctl: allow override of /proc/sys/net with CAP_NET_ADMIN
Extend the permission check for networking sysctl's to allow modification when current process has CAP_NET_ADMIN capability and is not root. This version uses the until now unused permissions hook to override the mode value for /proc/sys/net if accessed by a user with capabilities. Found while working with Quagga. It is impossible to turn forwarding on/off through the command interface because Quagga uses secure coding practice of dropping privledges during initialization and only raising via capabilities when necessary. Since the dameon has reset real/effective uid after initialization, all attempts to access /proc/sys/net variables will fail. Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrew Morgan <morgan@kernel.org> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'net/sysctl_net.c')
1 files changed, 14 insertions, 0 deletions
diff --git a/net/sysctl_net.c b/net/sysctl_net.c
index 007c1a6708ee..63ada437fc2f 100644
--- a/net/sysctl_net.c
+++ b/net/sysctl_net.c
@@ -35,8 +35,22 @@ net_ctl_header_lookup(struct ctl_table_root *root, struct nsproxy *namespaces)
return &namespaces->net_ns->sysctl_table_headers;
+/* Return standard mode bits for table entry. */
+static int net_ctl_permissions(struct ctl_table_root *root,
+ struct nsproxy *nsproxy,
+ struct ctl_table *table)
+ /* Allow network administrator to have same access as root. */
+ if (capable(CAP_NET_ADMIN)) {
+ int mode = (table->mode >> 6) & 7;
+ return (mode << 6) | (mode << 3) | mode;
+ }
+ return table->mode;
static struct ctl_table_root net_sysctl_root = {
.lookup = net_ctl_header_lookup,
+ .permissions = net_ctl_permissions,
static LIST_HEAD(net_sysctl_ro_tables);

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