[ 33/34] net: fix incorrect credentials passing

Greg Kroah-Hartman
2013-04-29T19:13:10Z

From: Linus Torvalds <torvalds@linux-foundation.org>

[ Upstream commit 83f1b4ba917db5dc5a061a44b3403ddb6e783494 ]

Commit 257b5358b32f ("scm: Capture the full credentials of the scm
sender") changed the credentials passing code to pass in the effective
uid/gid instead of the real uid/gid.

Obviously this doesn't matter most of the time (since normally they are
the same), but it results in differences for suid binaries when the wrong
uid/gid ends up being used.

This just undoes that (presumably unintentional) part of the commit.

Reported-by: Andy Lutomirski <luto@amacapital.net>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Serge E. Hallyn <serge@hallyn.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/socket.h | 3 ++-
include/net/scm.h | 2 +-
net/core/sock.c | 14 ++++++++++----
3 files changed, 13 insertions(+), 6 deletions(-)

--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -316,7 +316,8 @@ struct ucred {
/* IPX options */
#define IPX_TYPE 1

-extern void cred_to_ucred(struct pid *pid, const struct cred *cred, struct ucred *ucred);
+extern void cred_to_ucred(struct pid *pid, const struct cred *cred, struct ucred *ucred,
+ bool use_effective);

extern int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len);
extern int memcpy_fromiovecend(unsigned char *kdata, const struct iovec *iov,
--- a/include/net/scm.h
+++ b/include/net/scm.h
@@ -50,7 +50,7 @@ static __inline__ void scm_set_cred(stru
{
scm->pid = get_pid(pid);
scm->cred = cred ? get_cred(cred) : NULL;
- cred_to_ucred(pid, cred, &scm->creds);
+ cred_to_ucred(pid, cred, &scm->creds, false);
}

static __inline__ void scm_destroy_cred(struct scm_cookie *scm)
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -815,15 +815,20 @@ EXPORT_SYMBOL(sock_setsockopt);

void cred_to_ucred(struct pid *pid, const struct cred *cred,
- struct ucred *ucred)
+ struct ucred *ucred, bool use_effective)
{
ucred->pid = pid_vnr(pid);
ucred->uid = ucred->gid = -1;
if (cred) {
struct user_namespace *current_ns = current_user_ns();

- ucred->uid = user_ns_map_uid(current_ns, cred, cred->euid);
- ucred->gid = user_ns_map_gid(current_ns, cred, cred->egid);
+ if (use_effective) {
+ ucred->uid = user_ns_map_uid(current_ns, cred, cred->euid);
+ ucred->gid = user_ns_map_gid(current_ns, cred, cred->egid);
+ } else {
+ ucred->uid = user_ns_map_uid(current_ns, cred, cred->uid);
+ ucred->gid = user_ns_map_gid(current_ns, cred, cred->gid);
+ }
}
}
EXPORT_SYMBOL_GPL(cred_to_ucred);
@@ -984,7 +989,8 @@ int sock_getsockopt(struct socket *sock,
struct ucred peercred;
if (len > sizeof(peercred))
len = sizeof(peercred);
- cred_to_ucred(sk->sk_peer_pid, sk->sk_peer_cred, &peercred);
+ cred_to_ucred(sk->sk_peer_pid, sk->sk_peer_cred,
+ &peercred, true);
if (copy_to_user(optval, &peercred, len))
return -EFAULT;
goto lenout;