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net: netfilter: Add kfuncs to set and change CT status

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Introduce bpf_ct_set_status and bpf_ct_change_status kfunc helpers in
order to set nf_conn field of allocated entry or update nf_conn status
field of existing inserted entry. Use nf_ct_change_status_common to
share the permitted status field changes between netlink and BPF side
by refactoring ctnetlink_change_status.

It is required to introduce two kfuncs taking nf_conn___init and nf_conn
instead of sharing one because KF_TRUSTED_ARGS flag causes strict type
checking. This would disallow passing nf_conn___init to kfunc taking
nf_conn, and vice versa. We cannot remove the KF_TRUSTED_ARGS flag as we
only want to accept refcounted pointers and not e.g. ct->master.

Hence, bpf_ct_set_* kfuncs are meant to be used on allocated CT, and
bpf_ct_change_* kfuncs are meant to be used on inserted or looked up
CT entry.

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Co-developed-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220721134245.2450-10-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Lorenzo Bianconi 2022-07-21 15:42:41 +02:00 committed by Alexei Starovoitov
parent 0b38923644
commit ef69aa3a98
4 changed files with 76 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/net/netfilter/nf_conntrack_core.h
View File

@ -98,6 +98,8 @@ static inline void __nf_ct_set_timeout(struct nf_conn *ct, u64 timeout)
}
int __nf_ct_change_timeout(struct nf_conn *ct, u64 cta_timeout);
void __nf_ct_change_status(struct nf_conn *ct, unsigned long on, unsigned long off);
int nf_ct_change_status_common(struct nf_conn *ct, unsigned int status);
#endif

32
net/netfilter/nf_conntrack_bpf.c
View File

@ -394,6 +394,36 @@ int bpf_ct_change_timeout(struct nf_conn *nfct, u32 timeout)
return __nf_ct_change_timeout(nfct, msecs_to_jiffies(timeout));
}
/* bpf_ct_set_status - Set status field of allocated nf_conn
*
* Set the status field of the newly allocated nf_conn before insertion.
* This must be invoked for referenced PTR_TO_BTF_ID to nf_conn___init.
*
* Parameters:
* @nfct - Pointer to referenced nf_conn object, obtained using
* bpf_xdp_ct_alloc or bpf_skb_ct_alloc.
* @status - New status value.
*/
int bpf_ct_set_status(const struct nf_conn___init *nfct, u32 status)
{
return nf_ct_change_status_common((struct nf_conn *)nfct, status);
}
/* bpf_ct_change_status - Change status of inserted nf_conn
*
* Change the status field of the provided connection tracking entry.
* This must be invoked for referenced PTR_TO_BTF_ID to nf_conn.
*
* Parameters:
* @nfct - Pointer to referenced nf_conn object, obtained using
* bpf_ct_insert_entry, bpf_xdp_ct_lookup or bpf_skb_ct_lookup.
* @status - New status value.
*/
int bpf_ct_change_status(struct nf_conn *nfct, u32 status)
{
return nf_ct_change_status_common(nfct, status);
}
__diag_pop()
BTF_SET8_START(nf_ct_kfunc_set)
@ -405,6 +435,8 @@ BTF_ID_FLAGS(func, bpf_ct_insert_entry, KF_ACQUIRE | KF_RET_NULL | KF_RELEASE)
BTF_ID_FLAGS(func, bpf_ct_release, KF_RELEASE)
BTF_ID_FLAGS(func, bpf_ct_set_timeout, KF_TRUSTED_ARGS)
BTF_ID_FLAGS(func, bpf_ct_change_timeout, KF_TRUSTED_ARGS)
BTF_ID_FLAGS(func, bpf_ct_set_status, KF_TRUSTED_ARGS)
BTF_ID_FLAGS(func, bpf_ct_change_status, KF_TRUSTED_ARGS)
BTF_SET8_END(nf_ct_kfunc_set)
static const struct btf_kfunc_id_set nf_conntrack_kfunc_set = {

40
net/netfilter/nf_conntrack_core.c
View File

@ -2807,4 +2807,44 @@ int __nf_ct_change_timeout(struct nf_conn *ct, u64 timeout)
}
EXPORT_SYMBOL_GPL(__nf_ct_change_timeout);
void __nf_ct_change_status(struct nf_conn *ct, unsigned long on, unsigned long off)
{
unsigned int bit;
/* Ignore these unchangable bits */
on &= ~IPS_UNCHANGEABLE_MASK;
off &= ~IPS_UNCHANGEABLE_MASK;
for (bit = 0; bit < __IPS_MAX_BIT; bit++) {
if (on & (1 << bit))
set_bit(bit, &ct->status);
else if (off & (1 << bit))
clear_bit(bit, &ct->status);
}
}
EXPORT_SYMBOL_GPL(__nf_ct_change_status);
int nf_ct_change_status_common(struct nf_conn *ct, unsigned int status)
{
unsigned long d;
d = ct->status ^ status;
if (d & (IPS_EXPECTED|IPS_CONFIRMED|IPS_DYING))
/* unchangeable */
return -EBUSY;
if (d & IPS_SEEN_REPLY && !(status & IPS_SEEN_REPLY))
/* SEEN_REPLY bit can only be set */
return -EBUSY;
if (d & IPS_ASSURED && !(status & IPS_ASSURED))
/* ASSURED bit can only be set */
return -EBUSY;
__nf_ct_change_status(ct, status, 0);
return 0;
}
EXPORT_SYMBOL_GPL(nf_ct_change_status_common);
#endif

39
net/netfilter/nf_conntrack_netlink.c
View File

@ -1890,45 +1890,10 @@ ctnetlink_parse_nat_setup(struct nf_conn *ct,
}
#endif
static void
__ctnetlink_change_status(struct nf_conn *ct, unsigned long on,
unsigned long off)
{
unsigned int bit;
/* Ignore these unchangable bits */
on &= ~IPS_UNCHANGEABLE_MASK;
off &= ~IPS_UNCHANGEABLE_MASK;
for (bit = 0; bit < __IPS_MAX_BIT; bit++) {
if (on & (1 << bit))
set_bit(bit, &ct->status);
else if (off & (1 << bit))
clear_bit(bit, &ct->status);
}
}
static int
ctnetlink_change_status(struct nf_conn *ct, const struct nlattr * const cda[])
{
unsigned long d;
unsigned int status = ntohl(nla_get_be32(cda[CTA_STATUS]));
d = ct->status ^ status;
if (d & (IPS_EXPECTED|IPS_CONFIRMED|IPS_DYING))
/* unchangeable */
return -EBUSY;
if (d & IPS_SEEN_REPLY && !(status & IPS_SEEN_REPLY))
/* SEEN_REPLY bit can only be set */
return -EBUSY;
if (d & IPS_ASSURED && !(status & IPS_ASSURED))
/* ASSURED bit can only be set */
return -EBUSY;
__ctnetlink_change_status(ct, status, 0);
return 0;
return nf_ct_change_status_common(ct, ntohl(nla_get_be32(cda[CTA_STATUS])));
}
static int
@ -2825,7 +2790,7 @@ ctnetlink_update_status(struct nf_conn *ct, const struct nlattr * const cda[])
* unchangeable bits but do not error out. Also user programs
* are allowed to clear the bits that they are allowed to change.
*/
__ctnetlink_change_status(ct, status, ~status);
__nf_ct_change_status(ct, status, ~status);
return 0;
}