dbe9a4173e
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>
146 lines
3.6 KiB
C
146 lines
3.6 KiB
C
#ifndef __LINUX_NET_SCM_H
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#define __LINUX_NET_SCM_H
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#include <linux/limits.h>
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#include <linux/net.h>
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#include <linux/security.h>
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#include <linux/pid.h>
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#include <linux/nsproxy.h>
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/* Well, we should have at least one descriptor open
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* to accept passed FDs 8)
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*/
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#define SCM_MAX_FD 253
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struct scm_creds {
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u32 pid;
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kuid_t uid;
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kgid_t gid;
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};
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struct scm_fp_list {
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short count;
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short max;
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struct file *fp[SCM_MAX_FD];
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};
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struct scm_cookie {
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struct pid *pid; /* Skb credentials */
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const struct cred *cred;
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struct scm_fp_list *fp; /* Passed files */
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struct scm_creds creds; /* Skb credentials */
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#ifdef CONFIG_SECURITY_NETWORK
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u32 secid; /* Passed security ID */
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#endif
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};
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extern void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm);
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extern void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm);
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extern int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm);
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extern void __scm_destroy(struct scm_cookie *scm);
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extern struct scm_fp_list * scm_fp_dup(struct scm_fp_list *fpl);
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#ifdef CONFIG_SECURITY_NETWORK
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static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm)
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{
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security_socket_getpeersec_dgram(sock, NULL, &scm->secid);
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}
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#else
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static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm)
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{ }
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#endif /* CONFIG_SECURITY_NETWORK */
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static __inline__ void scm_set_cred(struct scm_cookie *scm,
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struct pid *pid, const struct cred *cred)
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{
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scm->pid = get_pid(pid);
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scm->cred = cred ? get_cred(cred) : NULL;
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scm->creds.pid = pid_vnr(pid);
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scm->creds.uid = cred ? cred->euid : INVALID_UID;
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scm->creds.gid = cred ? cred->egid : INVALID_GID;
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}
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static __inline__ void scm_destroy_cred(struct scm_cookie *scm)
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{
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put_pid(scm->pid);
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scm->pid = NULL;
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if (scm->cred)
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put_cred(scm->cred);
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scm->cred = NULL;
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}
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static __inline__ void scm_destroy(struct scm_cookie *scm)
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{
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scm_destroy_cred(scm);
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if (scm && scm->fp)
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__scm_destroy(scm);
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}
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static __inline__ int scm_send(struct socket *sock, struct msghdr *msg,
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struct scm_cookie *scm, bool forcecreds)
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{
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memset(scm, 0, sizeof(*scm));
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if (forcecreds)
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scm_set_cred(scm, task_tgid(current), current_cred());
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unix_get_peersec_dgram(sock, scm);
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if (msg->msg_controllen <= 0)
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return 0;
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return __scm_send(sock, msg, scm);
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}
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#ifdef CONFIG_SECURITY_NETWORK
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static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)
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{
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char *secdata;
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u32 seclen;
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int err;
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if (test_bit(SOCK_PASSSEC, &sock->flags)) {
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err = security_secid_to_secctx(scm->secid, &secdata, &seclen);
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if (!err) {
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put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, seclen, secdata);
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security_release_secctx(secdata, seclen);
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}
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}
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}
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#else
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static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)
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{ }
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#endif /* CONFIG_SECURITY_NETWORK */
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static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg,
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struct scm_cookie *scm, int flags)
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{
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if (!msg->msg_control) {
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if (test_bit(SOCK_PASSCRED, &sock->flags) || scm->fp)
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msg->msg_flags |= MSG_CTRUNC;
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scm_destroy(scm);
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return;
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}
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if (test_bit(SOCK_PASSCRED, &sock->flags)) {
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struct user_namespace *current_ns = current_user_ns();
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struct ucred ucreds = {
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.pid = scm->creds.pid,
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.uid = from_kuid_munged(current_ns, scm->creds.uid),
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.gid = from_kgid_munged(current_ns, scm->creds.gid),
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};
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put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(ucreds), &ucreds);
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}
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scm_destroy_cred(scm);
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scm_passec(sock, msg, scm);
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if (!scm->fp)
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return;
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scm_detach_fds(msg, scm);
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}
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#endif /* __LINUX_NET_SCM_H */
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