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netfilter: nf_tables: Audit log setelem reset
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Since set element reset is not integrated into nf_tables' transaction
logic, an explicit log call is needed, similar to NFT_MSG_GETOBJ_RESET
handling.

For the sake of simplicity, catchall element reset will always generate
a dedicated log entry. This relieves nf_tables_dump_set() from having to
adjust the logged element count depending on whether a catchall element
was found or not.

Fixes: 079cd63 ("netfilter: nf_tables: Introduce NFT_MSG_GETSETELEM_RESET")
Signed-off-by: Phil Sutter <[email protected]>
Reviewed-by: Richard Guy Briggs <[email protected]>
Signed-off-by: Pablo Neira Ayuso <[email protected]>
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Phil Sutter authored and ummakynes committed Aug 30, 2023
1 parent 69c5d28 commit 7e9be11
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Showing 3 changed files with 30 additions and 3 deletions.
1 change: 1 addition & 0 deletions include/linux/audit.h
Original file line number Diff line number Diff line change
Expand Up @@ -117,6 +117,7 @@ enum audit_nfcfgop {
AUDIT_NFT_OP_OBJ_RESET,
AUDIT_NFT_OP_FLOWTABLE_REGISTER,
AUDIT_NFT_OP_FLOWTABLE_UNREGISTER,
AUDIT_NFT_OP_SETELEM_RESET,
AUDIT_NFT_OP_INVALID,
};

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1 change: 1 addition & 0 deletions kernel/auditsc.c
Original file line number Diff line number Diff line change
Expand Up @@ -143,6 +143,7 @@ static const struct audit_nfcfgop_tab audit_nfcfgs[] = {
{ AUDIT_NFT_OP_OBJ_RESET, "nft_reset_obj" },
{ AUDIT_NFT_OP_FLOWTABLE_REGISTER, "nft_register_flowtable" },
{ AUDIT_NFT_OP_FLOWTABLE_UNREGISTER, "nft_unregister_flowtable" },
{ AUDIT_NFT_OP_SETELEM_RESET, "nft_reset_setelem" },
{ AUDIT_NFT_OP_INVALID, "nft_invalid" },
};

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31 changes: 28 additions & 3 deletions net/netfilter/nf_tables_api.c
Original file line number Diff line number Diff line change
Expand Up @@ -102,6 +102,7 @@ static const u8 nft2audit_op[NFT_MSG_MAX] = { // enum nf_tables_msg_types
[NFT_MSG_NEWFLOWTABLE] = AUDIT_NFT_OP_FLOWTABLE_REGISTER,
[NFT_MSG_GETFLOWTABLE] = AUDIT_NFT_OP_INVALID,
[NFT_MSG_DELFLOWTABLE] = AUDIT_NFT_OP_FLOWTABLE_UNREGISTER,
[NFT_MSG_GETSETELEM_RESET] = AUDIT_NFT_OP_SETELEM_RESET,
};

static void nft_validate_state_update(struct nft_table *table, u8 new_validate_state)
Expand Down Expand Up @@ -5624,13 +5625,25 @@ static int nf_tables_dump_setelem(const struct nft_ctx *ctx,
return nf_tables_fill_setelem(args->skb, set, elem, args->reset);
}

static void audit_log_nft_set_reset(const struct nft_table *table,
unsigned int base_seq,
unsigned int nentries)
{
char *buf = kasprintf(GFP_ATOMIC, "%s:%u", table->name, base_seq);

audit_log_nfcfg(buf, table->family, nentries,
AUDIT_NFT_OP_SETELEM_RESET, GFP_ATOMIC);
kfree(buf);
}

struct nft_set_dump_ctx {
const struct nft_set *set;
struct nft_ctx ctx;
};

static int nft_set_catchall_dump(struct net *net, struct sk_buff *skb,
const struct nft_set *set, bool reset)
const struct nft_set *set, bool reset,
unsigned int base_seq)
{
struct nft_set_elem_catchall *catchall;
u8 genmask = nft_genmask_cur(net);
Expand All @@ -5646,6 +5659,8 @@ static int nft_set_catchall_dump(struct net *net, struct sk_buff *skb,

elem.priv = catchall->elem;
ret = nf_tables_fill_setelem(skb, set, &elem, reset);
if (reset && !ret)
audit_log_nft_set_reset(set->table, base_seq, 1);
break;
}

Expand Down Expand Up @@ -5725,12 +5740,17 @@ static int nf_tables_dump_set(struct sk_buff *skb, struct netlink_callback *cb)
set->ops->walk(&dump_ctx->ctx, set, &args.iter);

if (!args.iter.err && args.iter.count == cb->args[0])
args.iter.err = nft_set_catchall_dump(net, skb, set, reset);
args.iter.err = nft_set_catchall_dump(net, skb, set,
reset, cb->seq);
rcu_read_unlock();

nla_nest_end(skb, nest);
nlmsg_end(skb, nlh);

if (reset && args.iter.count > args.iter.skip)
audit_log_nft_set_reset(table, cb->seq,
args.iter.count - args.iter.skip);

if (args.iter.err && args.iter.err != -EMSGSIZE)
return args.iter.err;
if (args.iter.count == cb->args[0])
Expand Down Expand Up @@ -5955,13 +5975,13 @@ static int nf_tables_getsetelem(struct sk_buff *skb,
struct netlink_ext_ack *extack = info->extack;
u8 genmask = nft_genmask_cur(info->net);
u8 family = info->nfmsg->nfgen_family;
int rem, err = 0, nelems = 0;
struct net *net = info->net;
struct nft_table *table;
struct nft_set *set;
struct nlattr *attr;
struct nft_ctx ctx;
bool reset = false;
int rem, err = 0;

table = nft_table_lookup(net, nla[NFTA_SET_ELEM_LIST_TABLE], family,
genmask, 0);
Expand Down Expand Up @@ -6004,8 +6024,13 @@ static int nf_tables_getsetelem(struct sk_buff *skb,
NL_SET_BAD_ATTR(extack, attr);
break;
}
nelems++;
}

if (reset)
audit_log_nft_set_reset(table, nft_pernet(net)->base_seq,
nelems);

return err;
}

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