Re: [PATCH v2] net: Add UNIX_DIAG_UID to Netlink UNIX socket diagnostics.
From: Andy Lutomirski <luto@amacapital.net>
Date: 2019-05-18 17:18:59
Also in:
lkml, netdev
quoted hunk ↗ jump to hunk
On May 17, 2019, at 8:48 PM, Felipe Gasper [off-list ref] wrote: Author: Felipe Gasper [off-list ref] Date: Fri May 17 16:54:40 2019 -0500 net: Add UNIX_DIAG_UID to Netlink UNIX socket diagnostics. This adds the ability for Netlink to report a socket’s UID along with the other UNIX diagnostic information that is already available. This will allow diagnostic tools greater insight into which users control which socket. Signed-off-by: Felipe Gasper [off-list ref]diff --git a/include/uapi/linux/unix_diag.h b/include/uapi/linux/unix_diag.h index 5c502fd..a198857 100644 --- a/include/uapi/linux/unix_diag.h +++ b/include/uapi/linux/unix_diag.h@@ -20,6 +20,7 @@ struct unix_diag_req {#define UDIAG_SHOW_ICONS 0x00000008 /* show pending connections */ #define UDIAG_SHOW_RQLEN 0x00000010 /* show skb receive queue len */ #define UDIAG_SHOW_MEMINFO 0x00000020 /* show memory info of a socket */ +#define UDIAG_SHOW_UID 0x00000040 /* show socket's UID */ struct unix_diag_msg { __u8 udiag_family;@@ -40,6 +41,7 @@ enum { UNIX_DIAG_RQLEN, UNIX_DIAG_MEMINFO, UNIX_DIAG_SHUTDOWN, + UNIX_DIAG_UID, __UNIX_DIAG_MAX,};diff --git a/net/unix/diag.c b/net/unix/diag.c index 3183d9b..e40f348 100644 --- a/net/unix/diag.c +++ b/net/unix/diag.c@@ -4,9 +4,11 @@#include <linux/unix_diag.h> #include <linux/skbuff.h> #include <linux/module.h> +#include <linux/uidgid.h> #include <net/netlink.h> #include <net/af_unix.h> #include <net/tcp_states.h> +#include <net/sock.h> static int sk_diag_dump_name(struct sock *sk, struct sk_buff *nlskb) {@@ -110,6 +112,12 @@ static int sk_diag_show_rqlen(struct sock *sk, struct sk_buff *nlskb) return nla_put(nlskb, UNIX_DIAG_RQLEN, sizeof(rql), &rql);} +static int sk_diag_dump_uid(struct sock *sk, struct sk_buff *nlskb) +{ + uid_t uid = from_kuid_munged(sk_user_ns(sk), sock_i_uid(sk)); + return nla_put(nlskb, UNIX_DIAG_UID, sizeof(uid_t), &uid);
This still looks wrong. You’re reporting the uid of the socket as seen by that socket. Presumably you actually want the uid of the socket as seen by the *diagnostic* socket. This might be sk_user_ns(nlskb->sk). You can test this with a command like unshare -U -r nc -l 12345 run as no -root. Then run you user diagnostic tool to find the uid of the socket. It should not be zero. Similarly, if you run unshare -U -r bash and then open a socket and run your diagnostic tool, both from that same session, you should see 0 as the uid since bash and all its children think they’re uid 0.
+}
quoted hunk ↗ jump to hunk
+ static int sk_diag_fill(struct sock *sk, struct sk_buff *skb, struct unix_diag_req *req, u32 portid, u32 seq, u32 flags, int sk_ino) {@@ -156,6 +164,10 @@ static int sk_diag_fill(struct sock *sk, struct sk_buff *skb, struct unix_diag_r if (nla_put_u8(skb, UNIX_DIAG_SHUTDOWN, sk->sk_shutdown)) goto out_nlmsg_trim; + if ((req->udiag_show & UDIAG_SHOW_UID) && + sk_diag_dump_uid(sk, skb)) + goto out_nlmsg_trim; + nlmsg_end(skb, nlh); return 0;