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authorDan Carpenter <dan.carpenter@linaro.org>2023-05-29 14:35:55 +0300
committerChuck Lever <chuck.lever@oracle.com>2023-05-31 09:57:14 -0400
commitc034203b6a9dae6751ef4371c18cb77983e30c28 (patch)
treeac499da052b4a58091c2eb857fdbdeb58ca7f692
parentd53d70084d27f56bcdf5074328f2c9ec861be596 (diff)
nfsd: fix double fget() bug in __write_ports_addfd()
The bug here is that you cannot rely on getting the same socket from multiple calls to fget() because userspace can influence that. This is a kind of double fetch bug. The fix is to delete the svc_alien_sock() function and instead do the checking inside the svc_addsock() function. Fixes: 3064639423c4 ("nfsd: check passed socket's net matches NFSd superblock's one") Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org> Reviewed-by: NeilBrown <neilb@suse.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
-rw-r--r--fs/nfsd/nfsctl.c7
-rw-r--r--include/linux/sunrpc/svcsock.h7
-rw-r--r--net/sunrpc/svcsock.c24
3 files changed, 10 insertions, 28 deletions
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index c159817d1282..b4fd7a7062d5 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -690,16 +690,11 @@ static ssize_t __write_ports_addfd(char *buf, struct net *net, const struct cred
if (err != 0 || fd < 0)
return -EINVAL;
- if (svc_alien_sock(net, fd)) {
- printk(KERN_ERR "%s: socket net is different to NFSd's one\n", __func__);
- return -EINVAL;
- }
-
err = nfsd_create_serv(net);
if (err != 0)
return err;
- err = svc_addsock(nn->nfsd_serv, fd, buf, SIMPLE_TRANSACTION_LIMIT, cred);
+ err = svc_addsock(nn->nfsd_serv, net, fd, buf, SIMPLE_TRANSACTION_LIMIT, cred);
if (err >= 0 &&
!nn->nfsd_serv->sv_nrthreads && !xchg(&nn->keep_active, 1))
diff --git a/include/linux/sunrpc/svcsock.h b/include/linux/sunrpc/svcsock.h
index d16ae621782c..a7116048a4d4 100644
--- a/include/linux/sunrpc/svcsock.h
+++ b/include/linux/sunrpc/svcsock.h
@@ -61,10 +61,9 @@ int svc_recv(struct svc_rqst *, long);
void svc_send(struct svc_rqst *rqstp);
void svc_drop(struct svc_rqst *);
void svc_sock_update_bufs(struct svc_serv *serv);
-bool svc_alien_sock(struct net *net, int fd);
-int svc_addsock(struct svc_serv *serv, const int fd,
- char *name_return, const size_t len,
- const struct cred *cred);
+int svc_addsock(struct svc_serv *serv, struct net *net,
+ const int fd, char *name_return, const size_t len,
+ const struct cred *cred);
void svc_init_xprt_sock(void);
void svc_cleanup_xprt_sock(void);
struct svc_xprt *svc_sock_create(struct svc_serv *serv, int prot);
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 63fe7a338992..f77cebe2c071 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -1480,25 +1480,10 @@ static struct svc_sock *svc_setup_socket(struct svc_serv *serv,
return svsk;
}
-bool svc_alien_sock(struct net *net, int fd)
-{
- int err;
- struct socket *sock = sockfd_lookup(fd, &err);
- bool ret = false;
-
- if (!sock)
- goto out;
- if (sock_net(sock->sk) != net)
- ret = true;
- sockfd_put(sock);
-out:
- return ret;
-}
-EXPORT_SYMBOL_GPL(svc_alien_sock);
-
/**
* svc_addsock - add a listener socket to an RPC service
* @serv: pointer to RPC service to which to add a new listener
+ * @net: caller's network namespace
* @fd: file descriptor of the new listener
* @name_return: pointer to buffer to fill in with name of listener
* @len: size of the buffer
@@ -1508,8 +1493,8 @@ EXPORT_SYMBOL_GPL(svc_alien_sock);
* Name is terminated with '\n'. On error, returns a negative errno
* value.
*/
-int svc_addsock(struct svc_serv *serv, const int fd, char *name_return,
- const size_t len, const struct cred *cred)
+int svc_addsock(struct svc_serv *serv, struct net *net, const int fd,
+ char *name_return, const size_t len, const struct cred *cred)
{
int err = 0;
struct socket *so = sockfd_lookup(fd, &err);
@@ -1520,6 +1505,9 @@ int svc_addsock(struct svc_serv *serv, const int fd, char *name_return,
if (!so)
return err;
+ err = -EINVAL;
+ if (sock_net(so->sk) != net)
+ goto out;
err = -EAFNOSUPPORT;
if ((so->sk->sk_family != PF_INET) && (so->sk->sk_family != PF_INET6))
goto out;