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author | Eric W. Biederman <ebiederm@xmission.com> | 2012-09-06 18:20:01 (GMT) |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2012-09-07 18:42:05 (GMT) |
commit | dbe9a4173ea53b72b2c35d19f676a85b69f1c9fe (patch) | |
tree | 49952d501032a2bc303d1d646ec6b1f00773b266 | |
parent | d679c5324d9a87c6295f56c2dea52d5f68834f41 (diff) | |
download | linux-fsl-qoriq-dbe9a4173ea53b72b2c35d19f676a85b69f1c9fe.tar.xz |
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>
-rw-r--r-- | include/linux/netlink.h | 3 | ||||
-rw-r--r-- | include/net/scm.h | 23 | ||||
-rw-r--r-- | net/core/scm.c | 17 | ||||
-rw-r--r-- | net/netlink/af_netlink.c | 2 |
4 files changed, 33 insertions, 12 deletions
diff --git a/include/linux/netlink.h b/include/linux/netlink.h index c9fdde2..df73cf4 100644 --- a/include/linux/netlink.h +++ b/include/linux/netlink.h @@ -153,6 +153,7 @@ struct nlattr { #include <linux/capability.h> #include <linux/skbuff.h> +#include <net/scm.h> struct net; @@ -162,7 +163,7 @@ static inline struct nlmsghdr *nlmsg_hdr(const struct sk_buff *skb) } struct netlink_skb_parms { - struct ucred creds; /* Skb credentials */ + struct scm_creds creds; /* Skb credentials */ __u32 pid; __u32 dst_group; struct sock *ssk; diff --git a/include/net/scm.h b/include/net/scm.h index 7dc0854..456695f 100644 --- a/include/net/scm.h +++ b/include/net/scm.h @@ -12,6 +12,12 @@ */ #define SCM_MAX_FD 253 +struct scm_creds { + u32 pid; + kuid_t uid; + kgid_t gid; +}; + struct scm_fp_list { short count; short max; @@ -22,7 +28,7 @@ struct scm_cookie { struct pid *pid; /* Skb credentials */ const struct cred *cred; struct scm_fp_list *fp; /* Passed files */ - struct ucred creds; /* Skb credentials */ + struct scm_creds creds; /* Skb credentials */ #ifdef CONFIG_SECURITY_NETWORK u32 secid; /* Passed security ID */ #endif @@ -49,7 +55,9 @@ static __inline__ void scm_set_cred(struct scm_cookie *scm, { scm->pid = get_pid(pid); scm->cred = cred ? get_cred(cred) : NULL; - cred_to_ucred(pid, cred, &scm->creds); + scm->creds.pid = pid_vnr(pid); + scm->creds.uid = cred ? cred->euid : INVALID_UID; + scm->creds.gid = cred ? cred->egid : INVALID_GID; } static __inline__ void scm_destroy_cred(struct scm_cookie *scm) @@ -112,8 +120,15 @@ static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg, return; } - if (test_bit(SOCK_PASSCRED, &sock->flags)) - put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(scm->creds), &scm->creds); + if (test_bit(SOCK_PASSCRED, &sock->flags)) { + struct user_namespace *current_ns = current_user_ns(); + struct ucred ucreds = { + .pid = scm->creds.pid, + .uid = from_kuid_munged(current_ns, scm->creds.uid), + .gid = from_kgid_munged(current_ns, scm->creds.gid), + }; + put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(ucreds), &ucreds); + } scm_destroy_cred(scm); diff --git a/net/core/scm.c b/net/core/scm.c index 6ab491d..9c1c63d 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 3821199..f530b1c 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)) { |