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Subject[PATCH ghak25 v3 1/3] audit: tidy and extend netfilter_cfg x_tables and ebtables logging
Date
NETFILTER_CFG record generation was inconsistent for x_tables and
ebtables configuration changes. The call was needlessly messy and there
were supporting records missing at times while they were produced when
not requested. Simplify the logging call into a new audit_log_nfcfg
call. Honour the audit_enabled setting while more consistently
recording information including supporting records by tidying up dummy
checks.

Add an op= field that indicates the operation being performed (register
or replace).

Here is the enhanced sample record:
type=NETFILTER_CFG msg=audit(1580905834.919:82970): table=filter family=2 entries=83 op=replace

Generate audit NETFILTER_CFG records on ebtables table registration.
Previously this was being done for x_tables registration and replacement
operations and ebtables table replacement only.

See: https://github.com/linux-audit/audit-kernel/issues/25
See: https://github.com/linux-audit/audit-kernel/issues/35
See: https://github.com/linux-audit/audit-kernel/issues/43

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
---
include/linux/audit.h | 19 +++++++++++++++++++
kernel/auditsc.c | 24 ++++++++++++++++++++++++
net/bridge/netfilter/ebtables.c | 12 ++++--------
net/netfilter/x_tables.c | 12 +++---------
4 files changed, 50 insertions(+), 17 deletions(-)

diff --git a/include/linux/audit.h b/include/linux/audit.h
index f9ceae57ca8d..f4aed2b9be8d 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -94,6 +94,11 @@ struct audit_ntp_data {
struct audit_ntp_data {};
#endif

+enum audit_nfcfgop {
+ AUDIT_XT_OP_REGISTER,
+ AUDIT_XT_OP_REPLACE,
+};
+
extern int is_audit_feature_set(int which);

extern int __init audit_register_class(int class, unsigned *list);
@@ -379,6 +384,8 @@ extern int __audit_log_bprm_fcaps(struct linux_binprm *bprm,
extern void __audit_fanotify(unsigned int response);
extern void __audit_tk_injoffset(struct timespec64 offset);
extern void __audit_ntp_log(const struct audit_ntp_data *ad);
+extern void __audit_log_nfcfg(const char *name, u8 af, unsigned int nentries,
+ enum audit_nfcfgop op);

static inline void audit_ipc_obj(struct kern_ipc_perm *ipcp)
{
@@ -514,6 +521,13 @@ static inline void audit_ntp_log(const struct audit_ntp_data *ad)
__audit_ntp_log(ad);
}

+static inline void audit_log_nfcfg(const char *name, u8 af, unsigned int nentries,
+ enum audit_nfcfgop op)
+{
+ if (audit_enabled)
+ __audit_log_nfcfg(name, af, nentries, op);
+}
+
extern int audit_n_rules;
extern int audit_signals;
#else /* CONFIG_AUDITSYSCALL */
@@ -646,6 +660,11 @@ static inline void audit_ntp_log(const struct audit_ntp_data *ad)

static inline void audit_ptrace(struct task_struct *t)
{ }
+
+static inline void audit_log_nfcfg(const char *name, u8 af, unsigned int nentries,
+ enum audit_nfcfgop op)
+{ }
+
#define audit_n_rules 0
#define audit_signals 0
#endif /* CONFIG_AUDITSYSCALL */
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 814406a35db1..f4e342125dd9 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -130,6 +130,16 @@ struct audit_tree_refs {
struct audit_chunk *c[31];
};

+struct audit_nfcfgop_tab {
+ enum audit_nfcfgop op;
+ const char *s;
+};
+
+const struct audit_nfcfgop_tab audit_nfcfgs[] = {
+ { AUDIT_XT_OP_REGISTER, "register" },
+ { AUDIT_XT_OP_REPLACE, "replace" },
+};
+
static int audit_match_perm(struct audit_context *ctx, int mask)
{
unsigned n;
@@ -2542,6 +2552,20 @@ void __audit_ntp_log(const struct audit_ntp_data *ad)
audit_log_ntp_val(ad, "adjust", AUDIT_NTP_ADJUST);
}

+void __audit_log_nfcfg(const char *name, u8 af, unsigned int nentries,
+ enum audit_nfcfgop op)
+{
+ struct audit_buffer *ab;
+
+ ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_NETFILTER_CFG);
+ if (!ab)
+ return;
+ audit_log_format(ab, "table=%s family=%u entries=%u op=%s",
+ name, af, nentries, audit_nfcfgs[op].s);
+ audit_log_end(ab);
+}
+EXPORT_SYMBOL_GPL(__audit_log_nfcfg);
+
static void audit_log_task(struct audit_buffer *ab)
{
kuid_t auid, uid;
diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index e1256e03a9a8..55f9409c3ee0 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -1046,14 +1046,8 @@ static int do_replace_finish(struct net *net, struct ebt_replace *repl,
vfree(table);
vfree(counterstmp);

-#ifdef CONFIG_AUDIT
- if (audit_enabled) {
- audit_log(audit_context(), GFP_KERNEL,
- AUDIT_NETFILTER_CFG,
- "table=%s family=%u entries=%u",
- repl->name, AF_BRIDGE, repl->nentries);
- }
-#endif
+ audit_log_nfcfg(repl->name, AF_BRIDGE, repl->nentries,
+ AUDIT_XT_OP_REPLACE);
return ret;

free_unlock:
@@ -1223,6 +1217,8 @@ int ebt_register_table(struct net *net, const struct ebt_table *input_table,
*res = NULL;
}

+ audit_log_nfcfg(repl->name, AF_BRIDGE, repl->nentries,
+ AUDIT_XT_OP_REGISTER);
return ret;
free_unlock:
mutex_unlock(&ebt_mutex);
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index e27c6c5ba9df..db5cbcf43748 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -1408,15 +1408,9 @@ struct xt_table_info *
}
}

-#ifdef CONFIG_AUDIT
- if (audit_enabled) {
- audit_log(audit_context(), GFP_KERNEL,
- AUDIT_NETFILTER_CFG,
- "table=%s family=%u entries=%u",
- table->name, table->af, private->number);
- }
-#endif
-
+ audit_log_nfcfg(table->name, table->af, private->number,
+ !private->number ? AUDIT_XT_OP_REGISTER :
+ AUDIT_XT_OP_REPLACE);
return private;
}
EXPORT_SYMBOL_GPL(xt_replace_table);
--
1.8.3.1
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