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authorEric W. Biederman <ebiederm@xmission.com>2012-09-06 22:20:01 +0400
committerDavid S. Miller <davem@davemloft.net>2012-09-07 22:42:05 +0400
commitdbe9a4173ea53b72b2c35d19f676a85b69f1c9fe (patch)
tree49952d501032a2bc303d1d646ec6b1f00773b266 /include/net/scm.h
parentd679c5324d9a87c6295f56c2dea52d5f68834f41 (diff)
downloadlinux-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>
Diffstat (limited to 'include/net/scm.h')
-rw-r--r--include/net/scm.h23
1 files changed, 19 insertions, 4 deletions
diff --git a/include/net/scm.h b/include/net/scm.h
index 7dc0854f0b38..456695f5cbc4 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);