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connector/cn_proc: Add filtering to fix some bugs

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The current proc connector code has the foll. bugs - if there are more
than one listeners for the proc connector messages, and one of them
deregisters for listening using PROC_CN_MCAST_IGNORE, they will still get
all proc connector messages, as long as there is another listener.

Another issue is if one client calls PROC_CN_MCAST_LISTEN, and another one
calls PROC_CN_MCAST_IGNORE, then both will end up not getting any messages.

This patch adds filtering and drops packet if client has sent
PROC_CN_MCAST_IGNORE. This data is stored in the client socket's
sk_user_data. In addition, we only increment or decrement
proc_event_num_listeners once per client. This fixes the above issues.

cn_release is the release function added for NETLINK_CONNECTOR. It uses
the newly added netlink_release function added to netlink_sock. It will
free sk_user_data.

Signed-off-by: Anjali Kulkarni <anjali.k.kulkarni@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Anjali Kulkarni 2023-07-19 13:18:18 -07:00 committed by David S. Miller
parent a4c9a56e6a
commit 2aa1f7a1f4
5 changed files with 100 additions and 35 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

53
drivers/connector/cn_proc.c
View file

@ -48,6 +48,21 @@ static DEFINE_PER_CPU(struct local_event, local_event) = {
.lock = INIT_LOCAL_LOCK(lock),
};
static int cn_filter(struct sock *dsk, struct sk_buff *skb, void *data)
{
enum proc_cn_mcast_op mc_op;
if (!dsk)
return 0;
mc_op = ((struct proc_input *)(dsk->sk_user_data))->mcast_op;
if (mc_op == PROC_CN_MCAST_IGNORE)
return 1;
return 0;
}
static inline void send_msg(struct cn_msg *msg)
{
local_lock(&local_event.lock);
@ -61,7 +76,8 @@ static inline void send_msg(struct cn_msg *msg)
*
* If cn_netlink_send() fails, the data is not sent.
*/
cn_netlink_send(msg, 0, CN_IDX_PROC, GFP_NOWAIT);
cn_netlink_send_mult(msg, msg->len, 0, CN_IDX_PROC, GFP_NOWAIT,
cn_filter, NULL);
local_unlock(&local_event.lock);
}
@ -346,11 +362,9 @@ static void cn_proc_ack(int err, int rcvd_seq, int rcvd_ack)
static void cn_proc_mcast_ctl(struct cn_msg *msg,
struct netlink_skb_parms *nsp)
{
enum proc_cn_mcast_op *mc_op = NULL;
int err = 0;
if (msg->len != sizeof(*mc_op))
return;
enum proc_cn_mcast_op mc_op = 0, prev_mc_op = 0;
int err = 0, initial = 0;
struct sock *sk = NULL;
/*
* Events are reported with respect to the initial pid
@ -367,12 +381,35 @@ static void cn_proc_mcast_ctl(struct cn_msg *msg,
goto out;
}
mc_op = (enum proc_cn_mcast_op *)msg->data;
switch (*mc_op) {
if (msg->len == sizeof(mc_op))
mc_op = *((enum proc_cn_mcast_op *)msg->data);
else
return;
if (nsp->sk) {
sk = nsp->sk;
if (sk->sk_user_data == NULL) {
sk->sk_user_data = kzalloc(sizeof(struct proc_input),
GFP_KERNEL);
if (sk->sk_user_data == NULL) {
err = ENOMEM;
goto out;
}
initial = 1;
} else {
prev_mc_op =
((struct proc_input *)(sk->sk_user_data))->mcast_op;
}
((struct proc_input *)(sk->sk_user_data))->mcast_op = mc_op;
}
switch (mc_op) {
case PROC_CN_MCAST_LISTEN:
if (initial || (prev_mc_op != PROC_CN_MCAST_LISTEN))
atomic_inc(&proc_event_num_listeners);
break;
case PROC_CN_MCAST_IGNORE:
if (!initial && (prev_mc_op != PROC_CN_MCAST_IGNORE))
atomic_dec(&proc_event_num_listeners);
break;
default:

21
drivers/connector/connector.c
View file

@ -59,7 +59,9 @@ static int cn_already_initialized;
* both, or if both are zero then the group is looked up and sent there.
*/
int cn_netlink_send_mult(struct cn_msg *msg, u16 len, u32 portid, u32 __group,
gfp_t gfp_mask)
gfp_t gfp_mask,
int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data),
void *filter_data)
{
struct cn_callback_entry *__cbq;
unsigned int size;
@ -110,8 +112,9 @@ int cn_netlink_send_mult(struct cn_msg *msg, u16 len, u32 portid, u32 __group,
NETLINK_CB(skb).dst_group = group;
if (group)
return netlink_broadcast(dev->nls, skb, portid, group,
gfp_mask);
return netlink_broadcast_filtered(dev->nls, skb, portid, group,
gfp_mask, filter,
(void *)filter_data);
return netlink_unicast(dev->nls, skb, portid,
!gfpflags_allow_blocking(gfp_mask));
}
@ -121,7 +124,8 @@ EXPORT_SYMBOL_GPL(cn_netlink_send_mult);
int cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __group,
gfp_t gfp_mask)
{
return cn_netlink_send_mult(msg, msg->len, portid, __group, gfp_mask);
return cn_netlink_send_mult(msg, msg->len, portid, __group, gfp_mask,
NULL, NULL);
}
EXPORT_SYMBOL_GPL(cn_netlink_send);
@ -162,6 +166,14 @@ static int cn_call_callback(struct sk_buff *skb)
return err;
}
static void cn_release(struct sock *sk, unsigned long *groups)
{
if (groups && test_bit(CN_IDX_PROC - 1, groups)) {
kfree(sk->sk_user_data);
sk->sk_user_data = NULL;
}
}
/*
* Main netlink receiving function.
*
@ -249,6 +261,7 @@ static int cn_init(void)
struct netlink_kernel_cfg cfg = {
.groups = CN_NETLINK_USERS + 0xf,
.input = cn_rx_skb,
.release = cn_release,
};
dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR, &cfg);

6
drivers/w1/w1_netlink.c
View file

@ -65,7 +65,8 @@ static void w1_unref_block(struct w1_cb_block *block)
u16 len = w1_reply_len(block);
if (len) {
cn_netlink_send_mult(block->first_cn, len,
block->portid, 0, GFP_KERNEL);
block->portid, 0,
GFP_KERNEL, NULL, NULL);
}
kfree(block);
}
@ -83,7 +84,8 @@ static void w1_reply_make_space(struct w1_cb_block *block, u16 space)
{
u16 len = w1_reply_len(block);
if (len + space >= block->maxlen) {
cn_netlink_send_mult(block->first_cn, len, block->portid, 0, GFP_KERNEL);
cn_netlink_send_mult(block->first_cn, len, block->portid,
0, GFP_KERNEL, NULL, NULL);
block->first_cn->len = 0;
block->cn = NULL;
block->msg = NULL;

8
include/linux/connector.h
View file

@ -90,13 +90,19 @@ void cn_del_callback(const struct cb_id *id);
* If @group is not zero, then message will be delivered
* to the specified group.
* @gfp_mask: GFP mask.
* @filter: Filter function to be used at netlink layer.
* @filter_data:Filter data to be supplied to the filter function
*
* It can be safely called from softirq context, but may silently
* fail under strong memory pressure.
*
* If there are no listeners for given group %-ESRCH can be returned.
*/
int cn_netlink_send_mult(struct cn_msg *msg, u16 len, u32 portid, u32 group, gfp_t gfp_mask);
int cn_netlink_send_mult(struct cn_msg *msg, u16 len, u32 portid,
u32 group, gfp_t gfp_mask,
int (*filter)(struct sock *dsk, struct sk_buff *skb,
void *data),
void *filter_data);
/**
* cn_netlink_send - Sends message to the specified groups.

43
include/uapi/linux/cn_proc.h
View file

@ -30,6 +30,30 @@ enum proc_cn_mcast_op {
PROC_CN_MCAST_IGNORE = 2
};
enum proc_cn_event {
/* Use successive bits so the enums can be used to record
* sets of events as well
*/
PROC_EVENT_NONE = 0x00000000,
PROC_EVENT_FORK = 0x00000001,
PROC_EVENT_EXEC = 0x00000002,
PROC_EVENT_UID = 0x00000004,
PROC_EVENT_GID = 0x00000040,
PROC_EVENT_SID = 0x00000080,
PROC_EVENT_PTRACE = 0x00000100,
PROC_EVENT_COMM = 0x00000200,
/* "next" should be 0x00000400 */
/* "last" is the last process event: exit,
* while "next to last" is coredumping event
*/
PROC_EVENT_COREDUMP = 0x40000000,
PROC_EVENT_EXIT = 0x80000000
};
struct proc_input {
enum proc_cn_mcast_op mcast_op;
};
/*
* From the user's point of view, the process
* ID is the thread group ID and thread ID is the internal
@ -44,24 +68,7 @@ enum proc_cn_mcast_op {
*/
struct proc_event {
enum what {
/* Use successive bits so the enums can be used to record
* sets of events as well
*/
PROC_EVENT_NONE = 0x00000000,
PROC_EVENT_FORK = 0x00000001,
PROC_EVENT_EXEC = 0x00000002,
PROC_EVENT_UID = 0x00000004,
PROC_EVENT_GID = 0x00000040,
PROC_EVENT_SID = 0x00000080,
PROC_EVENT_PTRACE = 0x00000100,
PROC_EVENT_COMM = 0x00000200,
/* "next" should be 0x00000400 */
/* "last" is the last process event: exit,
* while "next to last" is coredumping event */
PROC_EVENT_COREDUMP = 0x40000000,
PROC_EVENT_EXIT = 0x80000000
} what;
enum proc_cn_event what;
__u32 cpu;
__u64 __attribute__((aligned(8))) timestamp_ns;
/* Number of nano seconds since system boot */