4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Tyler Hicks tyhicks@canonical.com
[ Upstream commit 70ba5b6db96ff7324b8cfc87e0d0383cf59c9677 ]
The low and high values of the net.ipv4.ping_group_range sysctl were being silently forced to the default disabled state when a write to the sysctl contained GIDs that didn't map to the associated user namespace. Confusingly, the sysctl's write operation would return success and then a subsequent read of the sysctl would indicate that the low and high values are the overflowgid.
This patch changes the behavior by clearly returning an error when the sysctl write operation receives a GID range that doesn't map to the associated user namespace. In such a situation, the previous value of the sysctl is preserved and that range will be returned in a subsequent read of the sysctl.
Signed-off-by: Tyler Hicks tyhicks@canonical.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv4/sysctl_net_ipv4.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -140,8 +140,9 @@ static int ipv4_ping_group_range(struct if (write && ret == 0) { low = make_kgid(user_ns, urange[0]); high = make_kgid(user_ns, urange[1]); - if (!gid_valid(low) || !gid_valid(high) || - (urange[1] < urange[0]) || gid_lt(high, low)) { + if (!gid_valid(low) || !gid_valid(high)) + return -EINVAL; + if (urange[1] < urange[0] || gid_lt(high, low)) { low = make_kgid(&init_user_ns, 1); high = make_kgid(&init_user_ns, 0); }