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author | 2018-10-08 10:49:35 -0500 | |
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committer | 2018-10-15 21:37:58 -0700 | |
commit | 58f5bbe331c566f49c9559568f982202a278aa78 (patch) | |
tree | 013be2c5db2e21cdfafe6a249d6dac5790627c47 /net/core | |
parent | ethtool: fix a missing-check bug (diff) | |
download | linux-58f5bbe331c566f49c9559568f982202a278aa78.tar.gz linux-58f5bbe331c566f49c9559568f982202a278aa78.tar.bz2 linux-58f5bbe331c566f49c9559568f982202a278aa78.zip |
ethtool: fix a privilege escalation bug
In dev_ethtool(), the eth command 'ethcmd' is firstly copied from the
use-space buffer 'useraddr' and checked to see whether it is
ETHTOOL_PERQUEUE. If yes, the sub-command 'sub_cmd' is further copied from
the user space. Otherwise, 'sub_cmd' is the same as 'ethcmd'. Next,
according to 'sub_cmd', a permission check is enforced through the function
ns_capable(). For example, the permission check is required if 'sub_cmd' is
ETHTOOL_SCOALESCE, but it is not necessary if 'sub_cmd' is
ETHTOOL_GCOALESCE, as suggested in the comment "Allow some commands to be
done by anyone". The following execution invokes different handlers
according to 'ethcmd'. Specifically, if 'ethcmd' is ETHTOOL_PERQUEUE,
ethtool_set_per_queue() is called. In ethtool_set_per_queue(), the kernel
object 'per_queue_opt' is copied again from the user-space buffer
'useraddr' and 'per_queue_opt.sub_command' is used to determine which
operation should be performed. Given that the buffer 'useraddr' is in the
user space, a malicious user can race to change the sub-command between the
two copies. In particular, the attacker can supply ETHTOOL_PERQUEUE and
ETHTOOL_GCOALESCE to bypass the permission check in dev_ethtool(). Then
before ethtool_set_per_queue() is called, the attacker changes
ETHTOOL_GCOALESCE to ETHTOOL_SCOALESCE. In this way, the attacker can
bypass the permission check and execute ETHTOOL_SCOALESCE.
This patch enforces a check in ethtool_set_per_queue() after the second
copy from 'useraddr'. If the sub-command is different from the one obtained
in the first copy in dev_ethtool(), an error code EINVAL will be returned.
Fixes: f38d138a7da6 ("net/ethtool: support set coalesce per queue")
Signed-off-by: Wenwen Wang <wang6495@umn.edu>
Reviewed-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
-rw-r--r-- | net/core/ethtool.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/net/core/ethtool.c b/net/core/ethtool.c index 192f2f76b7bd..aeabc4831fca 100644 --- a/net/core/ethtool.c +++ b/net/core/ethtool.c @@ -2472,13 +2472,17 @@ roll_back: return ret; } -static int ethtool_set_per_queue(struct net_device *dev, void __user *useraddr) +static int ethtool_set_per_queue(struct net_device *dev, + void __user *useraddr, u32 sub_cmd) { struct ethtool_per_queue_op per_queue_opt; if (copy_from_user(&per_queue_opt, useraddr, sizeof(per_queue_opt))) return -EFAULT; + if (per_queue_opt.sub_command != sub_cmd) + return -EINVAL; + switch (per_queue_opt.sub_command) { case ETHTOOL_GCOALESCE: return ethtool_get_per_queue_coalesce(dev, useraddr, &per_queue_opt); @@ -2849,7 +2853,7 @@ int dev_ethtool(struct net *net, struct ifreq *ifr) rc = ethtool_get_phy_stats(dev, useraddr); break; case ETHTOOL_PERQUEUE: - rc = ethtool_set_per_queue(dev, useraddr); + rc = ethtool_set_per_queue(dev, useraddr, sub_cmd); break; case ETHTOOL_GLINKSETTINGS: rc = ethtool_get_link_ksettings(dev, useraddr); |