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authorEric W. Biederman <ebiederm@xmission.com>2012-09-06 18:20:01 +0000
committerDavid S. Miller <davem@davemloft.net>2012-09-07 14:42:05 -0400
commitdbe9a4173ea53b72b2c35d19f676a85b69f1c9fe (patch)
tree49952d501032a2bc303d1d646ec6b1f00773b266 /net
parentd679c5324d9a87c6295f56c2dea52d5f68834f41 (diff)
scm: Don't use struct ucred in NETLINK_CB and struct scm_cookie.
Passing uids and gids on NETLINK_CB from a process in one user namespace to a process in another user namespace can result in the wrong uid or gid being presented to userspace. Avoid that problem by passing kuids and kgids instead. - define struct scm_creds for use in scm_cookie and netlink_skb_parms that holds uid and gid information in kuid_t and kgid_t. - Modify scm_set_cred to fill out scm_creds by heand instead of using cred_to_ucred to fill out struct ucred. This conversion ensures userspace does not get incorrect uid or gid values to look at. - Modify scm_recv to convert from struct scm_creds to struct ucred before copying credential values to userspace. - Modify __scm_send to populate struct scm_creds on in the scm_cookie, instead of just copying struct ucred from userspace. - Modify netlink_sendmsg to copy scm_creds instead of struct ucred into the NETLINK_CB. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/core/scm.c17
-rw-r--r--net/netlink/af_netlink.c2
2 files changed, 12 insertions, 7 deletions
diff --git a/net/core/scm.c b/net/core/scm.c
index 6ab491d6c26f..9c1c63da3ca8 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -155,19 +155,21 @@ int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
break;
case SCM_CREDENTIALS:
{
+ struct ucred creds;
kuid_t uid;
kgid_t gid;
if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
goto error;
- memcpy(&p->creds, CMSG_DATA(cmsg), sizeof(struct ucred));
- err = scm_check_creds(&p->creds);
+ memcpy(&creds, CMSG_DATA(cmsg), sizeof(struct ucred));
+ err = scm_check_creds(&creds);
if (err)
goto error;
- if (!p->pid || pid_vnr(p->pid) != p->creds.pid) {
+ p->creds.pid = creds.pid;
+ if (!p->pid || pid_vnr(p->pid) != creds.pid) {
struct pid *pid;
err = -ESRCH;
- pid = find_get_pid(p->creds.pid);
+ pid = find_get_pid(creds.pid);
if (!pid)
goto error;
put_pid(p->pid);
@@ -175,11 +177,14 @@ int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
}
err = -EINVAL;
- uid = make_kuid(current_user_ns(), p->creds.uid);
- gid = make_kgid(current_user_ns(), p->creds.gid);
+ uid = make_kuid(current_user_ns(), creds.uid);
+ gid = make_kgid(current_user_ns(), creds.gid);
if (!uid_valid(uid) || !gid_valid(gid))
goto error;
+ p->creds.uid = uid;
+ p->creds.gid = gid;
+
if (!p->cred ||
!uid_eq(p->cred->euid, uid) ||
!gid_eq(p->cred->egid, gid)) {
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 382119917166..f530b1ca1773 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1399,7 +1399,7 @@ static int netlink_sendmsg(struct kiocb *kiocb, struct socket *sock,
NETLINK_CB(skb).pid = nlk->pid;
NETLINK_CB(skb).dst_group = dst_group;
- memcpy(NETLINK_CREDS(skb), &siocb->scm->creds, sizeof(struct ucred));
+ NETLINK_CB(skb).creds = siocb->scm->creds;
err = -EFAULT;
if (memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len)) {