can: proc: remove pointers from CAN specific proc output
Subsystems (5)
Oliver Hartkopp
maintainerPATCH v2 1/1 can: proc: remove pointers from CAN specific proc output
The proc content in /proc/net/can/ and /proc/net/can-bcm/ is intended to check the internal filter lists (af_can, can_raw) and the efficiency and functionality of can_bcm jobs. While exposing kernel addresses was acceptable when this code was written the times have changed and multiple attempts have been made to hash or remove such now sensitive data.
This patch removes the disclosure of pointers and instead provides the function names and sock inode numbers when available. In the case of KALLSYMS=n (EXPERT setting) the function names can not be resolved and (unknown) is printed instead. As there's no known tooling around the CAN specific proc output breaking the ABI with this rework creates no issue.
Suggested-by Sebastian Andrzej Siewior <[email protected]>
Signed-off-by Oliver Hartkopp <[email protected]>
---
v2: fix sashiko-bot remarks:
- don't use %ps when CONFIG_KALLSYMS=n and print (unknown) instead
- update documentation according to changed proc output example
- print sock inode numbers in decimal (%10llu) to match the representation in /proc/<pid>/fd and ss -e output
- keep decimal sock inode numbers for can-bcm proc filenames
--- Documentation/networking/can.rst | 12 ++++++------ include/linux/can/core.h | 2 +- net/can/af_can.c | 6 +++--- net/can/af_can.h | 2 +- net/can/bcm.c | 14 +++++++------- net/can/gw.c | 2 +- net/can/isotp.c | 4 ++-- net/can/j1939/main.c | 2 +- net/can/proc.c | 22 ++++++++++++---------- net/can/raw.c | 4 ++-- 10 files changed, 36 insertions(+), 34 deletions(-)
Documentation/networking/can.rst +6 -6
@@ -1038,21 +1038,21 @@ procfs content As described in :ref:`socketcan-receive-lists` the SocketCAN core uses several filter lists to deliver received CAN frames to CAN protocol modules. These receive lists, their filters and the count of filter matches can be checked in the appropriate receive list. All entries contain the -device and a protocol module identifier:: +CAN network device and the subscribed function name:: foo@bar:~$ cat /proc/net/can/rcvlist_all receive list 'rx_all': - (vcan3: no entry) - (vcan2: no entry) - (vcan1: no entry) - device can_id can_mask function userdata matches ident - vcan0 000 00000000 f88e6370 f6c6f400 0 raw (any: no entry) + device can_id can_mask matches sock_inode function + vcan0 000 00000000 0 63586 raw_rcv [can_raw] + (vcan1: no entry) + (vcan2: no entry) + (vcan3: no entry) In this example an application requests any CAN traffic from vcan0:: rcvlist_all - list for unfiltered entries (no filter operations) rcvlist_eff - list for single extended frame (EFF) entries
include/linux/can/core.h +1 -1
@@ -49,11 +49,11 @@ extern int can_proto_register(const struct can_proto *cp);extern void can_proto_unregister (const struct can_proto *cp);int can_rx_register (struct net *net,struct net_device *dev,canid_t can_id,canid_t mask,void (*func)(struct sk_buff *,void *), -void *data,char *ident,struct sock *sk); +void *data,u64 ino,struct sock *sk);extern void can_rx_unregister (struct net *net,struct net_device *dev,canid_t can_id,canid_t mask,void (*func)(struct sk_buff *,void *),void *data);
net/can/af_can.c +3 -3
@@ -416,11 +416,11 @@ static struct hlist_head *can_rcv_list_find(canid_t *can_id, canid_t *mask,* @dev: pointer to netdevice (NULL => subscribe from 'all' CAN devices list) * @can_id: CAN identifier (see description) * @mask: CAN mask (see description) * @func: callback function on filter match * @data: returned parameter for callback function -* @ident: string for calling module identification +* @ino: inode number of sock (0 = unknown) * @sk: socket pointer (might be NULL) * * Description: * Invokes the callback function with the received sk_buff and the given * parameter 'data' on a matching receive filter. A filter matches, when
@@ -441,11 +441,11 @@ static struct hlist_head *can_rcv_list_find(canid_t *can_id, canid_t *mask,* -ENOMEM on missing cache mem to create subscription entry * -ENODEV unknown device */ int can_rx_register (struct net *net,struct net_device *dev,canid_t can_id,canid_t mask,void (*func)(struct sk_buff *,void *), -void *data,char *ident,struct sock *sk) +void *data,u64 ino,struct sock *sk) {struct receiver *rcv;struct hlist_head *rcv_list;struct can_dev_rcv_lists *dev_rcv_lists;struct can_rcv_lists_stats *rcv_lists_stats = net->can.rcv_lists_stats;
@@ -470,11 +470,11 @@ int can_rx_register(struct net *net, struct net_device *dev, canid_t can_id, rcv->can_id = can_id; rcv->mask = mask;atomic_long_set (&rcv->matches,0 ); rcv->func = func; rcv->data = data; - rcv->ident = ident; + rcv->ino = ino; rcv->sk = sk;hlist_add_head_rcu (&rcv->list, rcv_list); dev_rcv_lists->entries++;
net/can/af_can.h +1 -1
@@ -53,11 +53,11 @@ struct receiver {canid_t can_id;canid_t mask;atomic_long_t matches;void (*func)(struct sk_buff *skb,void *data);void *data; -char *ident; +u64 ino;struct sock *sk;struct rcu_head rcu; };/* statistic structures */
net/can/bcm.c +7 -7
@@ -219,13 +219,11 @@ static int bcm_proc_show(struct seq_file *m, void *v)struct net *net = m->private;struct sock *sk = (struct sock *)pde_data (m->file->f_inode);struct bcm_sock *bo =bcm_sk (sk);struct bcm_op *op; -seq_printf (m,">>> socket %pK" , sk->sk_socket); -seq_printf (m," / sk %pK" , sk); -seq_printf (m," / bo %pK" , bo); +seq_printf (m,">>> sock inode %s" , bo->procname);seq_printf (m," / dropped %lu" , bo->dropped_usr_msgs);seq_printf (m," / bound %s" ,bcm_proc_getifname (net, ifname, bo->ifindex));seq_printf (m," <<<\n" );rcu_read_lock ();
@@ -1535,11 +1533,11 @@ static int bcm_rx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg,if (dev) { err =can_rx_register (sock_net (sk), dev, op->can_id,REGMASK (op->can_id), bcm_rx_handler, op, -"bcm" , sk); +sock_i_ino (sk), sk);/* keep a tracked reference so that a later * unregister can safely reach the device even * if a concurrent NETDEV_UNREGISTER has * already unlisted it by ifindex
@@ -1559,11 +1557,12 @@ static int bcm_rx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg, } }else { err =can_rx_register (sock_net (sk),NULL , op->can_id,REGMASK (op->can_id), - bcm_rx_handler, op,"bcm" , sk); + bcm_rx_handler, op, +sock_i_ino (sk), sk); }if (err) {/* newly created bcm rx op is broken -> remove it */ if (new_op) {
@@ -2039,12 +2038,13 @@ static int bcm_connect(struct socket *sock, struct sockaddr_unsized *uaddr, int bo->ifindex =0 ; }#if IS_ENABLED (CONFIG_PROC_FS )if (net->can.bcmproc_dir) { -/* unique socket address as filename */ -sprintf (bo->procname,"%llu" ,sock_i_ino (sk)); +/* use unique socket inode number as filename */ +snprintf (bo->procname,sizeof (bo->procname), +"%llu" ,sock_i_ino (sk)); bo->bcm_proc_read =proc_create_net_single (bo->procname,0644 , net->can.bcmproc_dir, bcm_proc_show, sk);if (!bo->bcm_proc_read) { ret = -ENOMEM ;
net/can/gw.c +1 -1
@@ -578,11 +578,11 @@ static void can_can_gw_rcv(struct sk_buff *skb, void *data)static inline int cgw_register_filter (struct net *net,struct cgw_job *gwj) {return can_rx_register (net, gwj->src.dev, gwj->ccgw.filter.can_id, gwj->ccgw.filter.can_mask, can_can_gw_rcv, - gwj,"gw" ,NULL ); + gwj,0 ,NULL ); }static inline void cgw_unregister_filter (struct net *net,struct cgw_job *gwj) { can_rx_unregister(net, gwj->src.dev, gwj->ccgw.filter.can_id,
net/can/isotp.c +2 -2
@@ -1624,18 +1624,18 @@ static int isotp_bind(struct socket *sock, struct sockaddr_unsized *uaddr, int l ifindex = dev->ifindex;if (isotp_register_rxid (so))can_rx_register (net, dev, rx_id,SINGLE_MASK (rx_id), - isotp_rcv, sk,"isotp" , sk); + isotp_rcv, sk,sock_i_ino (sk), sk);/* no consecutive frame echo skb in flight */ WRITE_ONCE (so->cfecho,0 );/* register for echo skb's */ can_rx_register (net, dev, tx_id,SINGLE_MASK (tx_id), - isotp_rcv_echo, sk,"isotpe" , sk); + isotp_rcv_echo, sk,sock_i_ino (sk), sk);/* switch to new settings */ so->ifindex = ifindex; so->rxid = rx_id; so->txid = tx_id;
net/can/j1939/main.c +1 -1
@@ -182,11 +182,11 @@ static int j1939_can_rx_register(struct j1939_priv *priv)struct net_device *ndev = priv->ndev;int ret;j1939_priv_get (priv); ret =can_rx_register (dev_net (ndev), ndev,J1939_CAN_ID ,J1939_CAN_MASK , - j1939_can_recv, priv,"j1939" ,NULL ); + j1939_can_recv, priv,0 ,NULL );if (ret <0 ) {j1939_priv_put (priv);return ret; }
net/can/proc.c +12 -10
@@ -213,29 +213,31 @@ static void can_print_rcvlist(struct seq_file *m, struct hlist_head *rx_list, {struct receiver *r;hlist_for_each_entry_rcu (r, rx_list, list) {char *fmt = (r->can_id &CAN_EFF_FLAG )? -" %-5s %08x %08x %pK %pK %8ld %s\n" : -" %-5s %03x %08x %pK %pK %8ld %s\n" ; +" %6s %08x %08x %8ld %10llu" : +" %6s %03x %08x %8ld %10llu" ;seq_printf (m, fmt,DNAME (dev), r->can_id, r->mask, - r->func, r->data,atomic_long_read (&r->matches), - r->ident); +atomic_long_read (&r->matches), r->ino); + +/* without kallsyms %ps would print the raw text address */ +if (IS_ENABLED (CONFIG_KALLSYMS )) +seq_printf (m," %ps\n" , r->func); +else +seq_puts (m," (unknown)\n" ); } }static void can_print_recv_banner (struct seq_file *m) {/* -* can1. 00000000 00000000 00000000 -* ....... 0 tp20 +* device can_id can_mask matches sock_inode function +* vcan0 000 00000000 0 43798 raw_rcv [can_raw] */ -if (IS_ENABLED (CONFIG_64BIT )) -seq_puts (m," device can_id can_mask function userdata matches ident\n" ); -else -seq_puts (m," device can_id can_mask function userdata matches ident\n" ); +seq_puts (m," device can_id can_mask matches sock_inode function\n" ); }static int can_stats_proc_show (struct seq_file *m,void *v) {struct net *net = m->private;
net/can/raw.c +2 -2
@@ -224,11 +224,11 @@ static int raw_enable_filters(struct net *net, struct net_device *dev,int i;for (i =0 ; i < count; i++) { err =can_rx_register (net, dev, filter[i].can_id, filter[i].can_mask, - raw_rcv, sk,"raw" , sk); + raw_rcv, sk,sock_i_ino (sk), sk);if (err) {/* clean up successfully registered filters */ while (--i >=0 ) can_rx_unregister(net, dev, filter[i].can_id, filter[i].can_mask,
@@ -245,11 +245,11 @@ static int raw_enable_errfilter(struct net *net, struct net_device *dev, {int err =0 ;if (err_mask) err =can_rx_register (net, dev,0 , err_mask |CAN_ERR_FLAG , - raw_rcv, sk,"raw" , sk); + raw_rcv, sk,sock_i_ino (sk), sk);return err; } static void raw_disable_filters(struct net *net, struct net_device *dev,
Signature · 1 line
2.53.0
Marc Kleine-Budde
maintainerQuoted 6 lines · Oliver Hartkopp
The proc content in
/proc/net/can/and/proc/net/can-bcm/is intended to check the internal filter lists (af_can,can_raw) and the efficiency and functionality ofcan_bcmjobs. While exposing kernel addresses was acceptable when this code was written the times have changed and multiple attempts have been made to hash or remove such now sensitive data.
Quoted 8 lines
This patch removes the disclosure of pointers and instead provides the function names and sock inode numbers when available. In the case of KALLSYMS=n (EXPERT setting) the function names can not be resolved and (unknown) is printed instead. As there's no known tooling around the CAN specific proc output breaking the ABI with this rework creates no issue.
Suggested-by Sebastian Andrzej Siewior <[email protected]>Signed-off-by Oliver Hartkopp <[email protected]>
I've replaced the v1.
Thanks,
Marc
pw-bot: accepted
Signature · 4 lines
Pengutronix e.K. | Marc Kleine-Budde | Embedded Linux | https://www.pengutronix.de | Vertretung Nürnberg | Phone: +49-5121-206917-129 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-9 |