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scm: Capture the full credentials of the scm sender.

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Start capturing not only the userspace pid, uid and gid values of the
sending process but also the struct pid and struct cred of the sending
process as well.

This is in preparation for properly supporting SCM_CREDENTIALS for
sockets that have different uid and/or pid namespaces at the different
ends.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Serge E. Hallyn <serge@hallyn.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric W. Biederman 2010-06-13 03:32:34 +00:00 committed by David S. Miller
parent b47030c71d
commit 257b5358b3
2 changed files with 48 additions and 4 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

28
include/net/scm.h
View file

@ -19,6 +19,8 @@ struct scm_fp_list {
}; };
struct scm_cookie { struct scm_cookie {
struct pid *pid; /* Skb credentials */
const struct cred *cred;
struct scm_fp_list *fp; /* Passed files */ struct scm_fp_list *fp; /* Passed files */
struct ucred creds; /* Skb credentials */ struct ucred creds; /* Skb credentials */
#ifdef CONFIG_SECURITY_NETWORK #ifdef CONFIG_SECURITY_NETWORK
@ -42,8 +44,27 @@ static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_co
{ } { }
#endif /* CONFIG_SECURITY_NETWORK */ #endif /* CONFIG_SECURITY_NETWORK */
static __inline__ void scm_set_cred(struct scm_cookie *scm,
struct pid *pid, const struct cred *cred)
{
scm->pid = get_pid(pid);
scm->cred = get_cred(cred);
cred_to_ucred(pid, cred, &scm->creds);
}
static __inline__ void scm_destroy_cred(struct scm_cookie *scm)
{
put_pid(scm->pid);
scm->pid = NULL;
if (scm->cred)
put_cred(scm->cred);
scm->cred = NULL;
}
static __inline__ void scm_destroy(struct scm_cookie *scm) static __inline__ void scm_destroy(struct scm_cookie *scm)
{ {
scm_destroy_cred(scm);
if (scm && scm->fp) if (scm && scm->fp)
__scm_destroy(scm); __scm_destroy(scm);
} }
@ -51,10 +72,7 @@ static __inline__ void scm_destroy(struct scm_cookie *scm)
static __inline__ int scm_send(struct socket *sock, struct msghdr *msg, static __inline__ int scm_send(struct socket *sock, struct msghdr *msg,
struct scm_cookie *scm) struct scm_cookie *scm)
{ {
struct task_struct *p = current; scm_set_cred(scm, task_tgid(current), current_cred());
scm->creds.uid = current_uid();
scm->creds.gid = current_gid();
scm->creds.pid = task_tgid_vnr(p);
scm->fp = NULL; scm->fp = NULL;
unix_get_peersec_dgram(sock, scm); unix_get_peersec_dgram(sock, scm);
if (msg->msg_controllen <= 0) if (msg->msg_controllen <= 0)
@ -96,6 +114,8 @@ static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg,
if (test_bit(SOCK_PASSCRED, &sock->flags)) if (test_bit(SOCK_PASSCRED, &sock->flags))
put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(scm->creds), &scm->creds); put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(scm->creds), &scm->creds);
scm_destroy_cred(scm);
scm_passec(sock, msg, scm); scm_passec(sock, msg, scm);
if (!scm->fp) if (!scm->fp)

24
net/core/scm.c
View file

@ -170,6 +170,30 @@ int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
err = scm_check_creds(&p->creds); err = scm_check_creds(&p->creds);
if (err) if (err)
goto error; goto error;
if (pid_vnr(p->pid) != p->creds.pid) {
struct pid *pid;
err = -ESRCH;
pid = find_get_pid(p->creds.pid);
if (!pid)
goto error;
put_pid(p->pid);
p->pid = pid;
}
if ((p->cred->euid != p->creds.uid) ||
(p->cred->egid != p->creds.gid)) {
struct cred *cred;
err = -ENOMEM;
cred = prepare_creds();
if (!cred)
goto error;
cred->uid = cred->euid = p->creds.uid;
cred->gid = cred->egid = p->creds.uid;
put_cred(p->cred);
p->cred = cred;
}
break; break;
default: default:
goto error; goto error;