When NET_NS is not enabled, socket ioctl cmd SIOCGSKNS should do nothing but acknowledge userspace it is not supported. Otherwise, kernel would panic wherever nsfs trys to access ns->ops since the proc_ns_operations is not implemented in this case.
[7.670023] Unable to handle kernel NULL pointer dereference at virtual address 00000010 [7.670268] pgd = 32b54000 [7.670544] [00000010] *pgd=00000000 [7.671861] Internal error: Oops: 5 [#1] SMP ARM [7.672315] Modules linked in: [7.672918] CPU: 0 PID: 1 Comm: systemd Not tainted 5.13.0-rc3-00375-g6799d4f2da49 #16 [7.673309] Hardware name: Generic DT based system [7.673642] PC is at nsfs_evict+0x24/0x30 [7.674486] LR is at clear_inode+0x20/0x9c
Signed-off-by: Changbin Du changbin.du@gmail.com Cc: stable@vger.kernel.org # v4.9 --- net/socket.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/net/socket.c b/net/socket.c index 27e3e7d53f8e..644b46112d35 100644 --- a/net/socket.c +++ b/net/socket.c @@ -1149,11 +1149,15 @@ static long sock_ioctl(struct file *file, unsigned cmd, unsigned long arg) mutex_unlock(&vlan_ioctl_mutex); break; case SIOCGSKNS: +#ifdef CONFIG_NET_NS err = -EPERM; if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) break;
err = open_related_ns(&net->ns, get_net_ns); +#else + err = -ENOTSUPP; +#endif break; case SIOCGSTAMP_OLD: case SIOCGSTAMPNS_OLD:
On Sat, 29 May 2021 14:05:26 +0800 Changbin Du wrote:
When NET_NS is not enabled, socket ioctl cmd SIOCGSKNS should do nothing but acknowledge userspace it is not supported. Otherwise, kernel would panic wherever nsfs trys to access ns->ops since the proc_ns_operations is not implemented in this case.
[7.670023] Unable to handle kernel NULL pointer dereference at virtual address 00000010 [7.670268] pgd = 32b54000 [7.670544] [00000010] *pgd=00000000 [7.671861] Internal error: Oops: 5 [#1] SMP ARM [7.672315] Modules linked in: [7.672918] CPU: 0 PID: 1 Comm: systemd Not tainted 5.13.0-rc3-00375-g6799d4f2da49 #16 [7.673309] Hardware name: Generic DT based system [7.673642] PC is at nsfs_evict+0x24/0x30 [7.674486] LR is at clear_inode+0x20/0x9c
Signed-off-by: Changbin Du changbin.du@gmail.com Cc: stable@vger.kernel.org # v4.9
Please provide a Fixes tag.
diff --git a/net/socket.c b/net/socket.c index 27e3e7d53f8e..644b46112d35 100644 --- a/net/socket.c +++ b/net/socket.c @@ -1149,11 +1149,15 @@ static long sock_ioctl(struct file *file, unsigned cmd, unsigned long arg) mutex_unlock(&vlan_ioctl_mutex); break; case SIOCGSKNS: +#ifdef CONFIG_NET_NS err = -EPERM; if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) break; err = open_related_ns(&net->ns, get_net_ns);
There's a few more places with this exact code. Can we please add the check in get_net_ns? That should fix all callers.
+#else
err = -ENOTSUPP;
EOPNOTSUPP, you shouldn't return ENOTSUPP to user space.
+#endif break; case SIOCGSTAMP_OLD: case SIOCGSTAMPNS_OLD:
On Sat, May 29, 2021 at 11:27:35AM -0700, Jakub Kicinski wrote:
On Sat, 29 May 2021 14:05:26 +0800 Changbin Du wrote:
When NET_NS is not enabled, socket ioctl cmd SIOCGSKNS should do nothing but acknowledge userspace it is not supported. Otherwise, kernel would panic wherever nsfs trys to access ns->ops since the proc_ns_operations is not implemented in this case.
[7.670023] Unable to handle kernel NULL pointer dereference at virtual address 00000010 [7.670268] pgd = 32b54000 [7.670544] [00000010] *pgd=00000000 [7.671861] Internal error: Oops: 5 [#1] SMP ARM [7.672315] Modules linked in: [7.672918] CPU: 0 PID: 1 Comm: systemd Not tainted 5.13.0-rc3-00375-g6799d4f2da49 #16 [7.673309] Hardware name: Generic DT based system [7.673642] PC is at nsfs_evict+0x24/0x30 [7.674486] LR is at clear_inode+0x20/0x9c
Signed-off-by: Changbin Du changbin.du@gmail.com Cc: stable@vger.kernel.org # v4.9
Please provide a Fixes tag.
Now it will be fixed by nsfs side. And the code has been changed to many times..
diff --git a/net/socket.c b/net/socket.c index 27e3e7d53f8e..644b46112d35 100644 --- a/net/socket.c +++ b/net/socket.c @@ -1149,11 +1149,15 @@ static long sock_ioctl(struct file *file, unsigned cmd, unsigned long arg) mutex_unlock(&vlan_ioctl_mutex); break; case SIOCGSKNS: +#ifdef CONFIG_NET_NS err = -EPERM; if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) break; err = open_related_ns(&net->ns, get_net_ns);
There's a few more places with this exact code. Can we please add the check in get_net_ns? That should fix all callers.
+#else
err = -ENOTSUPP;EOPNOTSUPP, you shouldn't return ENOTSUPP to user space.
Thanks for pointing out. Will change it.
+#endif break; case SIOCGSTAMP_OLD: case SIOCGSTAMPNS_OLD:
On Fri, May 28, 2021 at 11:08 PM Changbin Du changbin.du@gmail.com wrote:
diff --git a/net/socket.c b/net/socket.c index 27e3e7d53f8e..644b46112d35 100644 --- a/net/socket.c +++ b/net/socket.c @@ -1149,11 +1149,15 @@ static long sock_ioctl(struct file *file, unsigned cmd, unsigned long arg) mutex_unlock(&vlan_ioctl_mutex); break; case SIOCGSKNS: +#ifdef CONFIG_NET_NS err = -EPERM; if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) break;
err = open_related_ns(&net->ns, get_net_ns);+#else
err = -ENOTSUPP;+#endif
I wonder if it is easier if we just reject ns->ops==NULL case in open_related_ns(). For 1) we can save an ugly #ifdef here; 2) drivers/net/tun.c has the same bugs.
Something like this:
diff --git a/fs/nsfs.c b/fs/nsfs.c index 800c1d0eb0d0..d63414604e99 100644 --- a/fs/nsfs.c +++ b/fs/nsfs.c @@ -152,6 +152,9 @@ int open_related_ns(struct ns_common *ns, int err; int fd;
+ if (!ns->ops) + return -EOPNOTSUPP; + fd = get_unused_fd_flags(O_CLOEXEC); if (fd < 0) return fd;
From: Cong Wang
Sent: 29 May 2021 20:15
On Fri, May 28, 2021 at 11:08 PM Changbin Du changbin.du@gmail.com wrote:
diff --git a/net/socket.c b/net/socket.c index 27e3e7d53f8e..644b46112d35 100644 --- a/net/socket.c +++ b/net/socket.c @@ -1149,11 +1149,15 @@ static long sock_ioctl(struct file *file, unsigned cmd, unsigned long arg) mutex_unlock(&vlan_ioctl_mutex); break; case SIOCGSKNS: +#ifdef CONFIG_NET_NS err = -EPERM; if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) break;
err = open_related_ns(&net->ns, get_net_ns);+#else
err = -ENOTSUPP;+#endif
I wonder if it is easier if we just reject ns->ops==NULL case in open_related_ns(). For 1) we can save an ugly #ifdef here; 2) drivers/net/tun.c has the same bugs.
If CONFIG_NET_NS is unset then why not make both ns_capable() and open_related_ns() unconditionally return -ENOTSUPP?
David
- Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
On Mon, May 31, 2021 at 08:30:58AM +0000, David Laight wrote:
From: Cong Wang
Sent: 29 May 2021 20:15
On Fri, May 28, 2021 at 11:08 PM Changbin Du changbin.du@gmail.com wrote:
diff --git a/net/socket.c b/net/socket.c index 27e3e7d53f8e..644b46112d35 100644 --- a/net/socket.c +++ b/net/socket.c @@ -1149,11 +1149,15 @@ static long sock_ioctl(struct file *file, unsigned cmd, unsigned long arg) mutex_unlock(&vlan_ioctl_mutex); break; case SIOCGSKNS: +#ifdef CONFIG_NET_NS err = -EPERM; if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) break;
err = open_related_ns(&net->ns, get_net_ns);+#else
err = -ENOTSUPP;+#endif
I wonder if it is easier if we just reject ns->ops==NULL case in open_related_ns(). For 1) we can save an ugly #ifdef here; 2) drivers/net/tun.c has the same bugs.
If CONFIG_NET_NS is unset then why not make both ns_capable() and open_related_ns() unconditionally return -ENOTSUPP?
Here is the new fix that reject creating indoe for disabled ns. --- a/fs/nsfs.c +++ b/fs/nsfs.c @@ -62,6 +62,10 @@ static int __ns_get_path(struct path *path, struct ns_common *ns) struct inode *inode; unsigned long d;
+ /* In case the namespace is not actually enabled. */ + if (!ns->ops) + return -EOPNOTSUPP;
David
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
linux-stable-mirror@lists.linaro.org
-
Changbin Du -
Cong Wang -
David Laight -
Jakub Kicinski