[PATCH ghak90 V8 10/16] audit: add containerid filtering

From: Richard Guy Briggs
Date: Tue Dec 31 2019 - 14:51:10 EST

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Implement audit container identifier filtering using the AUDIT_CONTID
field name to send an 8-character string representing a u64 since the
value field is only u32.

Sending it as two u32 was considered, but gathering and comparing two
fields was more complex.

The feature indicator is AUDIT_FEATURE_BITMAP_CONTAINERID.

Please see the github audit kernel issue for the contid filter feature:
https://github.com/linux-audit/audit-kernel/issues/91
Please see the github audit userspace issue for filter additions:
https://github.com/linux-audit/audit-userspace/issues/40
Please see the github audit testsuiite issue for the test case:
https://github.com/linux-audit/audit-testsuite/issues/64
Please see the github audit wiki for the feature overview:
https://github.com/linux-audit/audit-kernel/wiki/RFE-Audit-Container-ID
Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
Acked-by: Serge Hallyn <serge@xxxxxxxxxx>
Acked-by: Neil Horman <nhorman@xxxxxxxxxxxxx>
Reviewed-by: Ondrej Mosnacek <omosnace@xxxxxxxxxx>
---
include/linux/audit.h | 1 +
include/uapi/linux/audit.h | 5 ++++-
kernel/audit.h | 1 +
kernel/auditfilter.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
kernel/auditsc.c | 4 ++++
5 files changed, 56 insertions(+), 1 deletion(-)

diff --git a/include/linux/audit.h b/include/linux/audit.h
index 29b81cc43f8d..5531d37a4226 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -68,6 +68,7 @@ struct audit_field {
u32 type;
union {
u32 val;
+ u64 val64;
kuid_t uid;
kgid_t gid;
struct {
diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
index 4f87b06f0acd..ea6638bb914b 100644
--- a/include/uapi/linux/audit.h
+++ b/include/uapi/linux/audit.h
@@ -269,6 +269,7 @@
#define AUDIT_LOGINUID_SET 24
#define AUDIT_SESSIONID 25 /* Session ID */
#define AUDIT_FSTYPE 26 /* FileSystem Type */
+#define AUDIT_CONTID 27 /* Container ID */

/* These are ONLY useful when checking
* at syscall exit time (AUDIT_AT_EXIT). */
@@ -350,6 +351,7 @@ enum {
#define AUDIT_FEATURE_BITMAP_SESSIONID_FILTER 0x00000010
#define AUDIT_FEATURE_BITMAP_LOST_RESET 0x00000020
#define AUDIT_FEATURE_BITMAP_FILTER_FS 0x00000040
+#define AUDIT_FEATURE_BITMAP_CONTAINERID 0x00000080

#define AUDIT_FEATURE_BITMAP_ALL (AUDIT_FEATURE_BITMAP_BACKLOG_LIMIT | \
AUDIT_FEATURE_BITMAP_BACKLOG_WAIT_TIME | \
@@ -357,7 +359,8 @@ enum {
AUDIT_FEATURE_BITMAP_EXCLUDE_EXTEND | \
AUDIT_FEATURE_BITMAP_SESSIONID_FILTER | \
AUDIT_FEATURE_BITMAP_LOST_RESET | \
- AUDIT_FEATURE_BITMAP_FILTER_FS)
+ AUDIT_FEATURE_BITMAP_FILTER_FS | \
+ AUDIT_FEATURE_BITMAP_CONTAINERID)

/* deprecated: AUDIT_VERSION_* */
#define AUDIT_VERSION_LATEST AUDIT_FEATURE_BITMAP_ALL
diff --git a/kernel/audit.h b/kernel/audit.h
index 000ca7c89f6d..5e2f5c9820d8 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -225,6 +225,7 @@ static inline int audit_hash_contid(u64 contid)

extern int audit_match_class(int class, unsigned syscall);
extern int audit_comparator(const u32 left, const u32 op, const u32 right);
+extern int audit_comparator64(const u64 left, const u32 op, const u64 right);
extern int audit_uid_comparator(kuid_t left, u32 op, kuid_t right);
extern int audit_gid_comparator(kgid_t left, u32 op, kgid_t right);
extern int parent_len(const char *path);
diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index b0126e9c0743..9606f973fe33 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -399,6 +399,7 @@ static int audit_field_valid(struct audit_entry *entry, struct audit_field *f)
case AUDIT_FILETYPE:
case AUDIT_FIELD_COMPARE:
case AUDIT_EXE:
+ case AUDIT_CONTID:
/* only equal and not equal valid ops */
if (f->op != Audit_not_equal && f->op != Audit_equal)
return -EINVAL;
@@ -586,6 +587,14 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
}
entry->rule.exe = audit_mark;
break;
+ case AUDIT_CONTID:
+ if (f->val != sizeof(u64))
+ goto exit_free;
+ str = audit_unpack_string(&bufp, &remain, f->val);
+ if (IS_ERR(str))
+ goto exit_free;
+ f->val64 = ((u64 *)str)[0];
+ break;
}
}

@@ -668,6 +677,11 @@ static struct audit_rule_data *audit_krule_to_data(struct audit_krule *krule)
data->buflen += data->values[i] =
audit_pack_string(&bufp, audit_mark_path(krule->exe));
break;
+ case AUDIT_CONTID:
+ data->buflen += data->values[i] = sizeof(u64);
+ memcpy(bufp, &f->val64, sizeof(u64));
+ bufp += sizeof(u64);
+ break;
case AUDIT_LOGINUID_SET:
if (krule->pflags & AUDIT_LOGINUID_LEGACY && !f->val) {
data->fields[i] = AUDIT_LOGINUID;
@@ -754,6 +768,10 @@ static int audit_compare_rule(struct audit_krule *a, struct audit_krule *b)
if (!gid_eq(a->fields[i].gid, b->fields[i].gid))
return 1;
break;
+ case AUDIT_CONTID:
+ if (a->fields[i].val64 != b->fields[i].val64)
+ return 1;
+ break;
default:
if (a->fields[i].val != b->fields[i].val)
return 1;
@@ -1211,6 +1229,30 @@ int audit_comparator(u32 left, u32 op, u32 right)
}
}

+int audit_comparator64(u64 left, u32 op, u64 right)
+{
+ switch (op) {
+ case Audit_equal:
+ return (left == right);
+ case Audit_not_equal:
+ return (left != right);
+ case Audit_lt:
+ return (left < right);
+ case Audit_le:
+ return (left <= right);
+ case Audit_gt:
+ return (left > right);
+ case Audit_ge:
+ return (left >= right);
+ case Audit_bitmask:
+ return (left & right);
+ case Audit_bittest:
+ return ((left & right) == right);
+ default:
+ return 0;
+ }
+}
+
int audit_uid_comparator(kuid_t left, u32 op, kuid_t right)
{
switch (op) {
@@ -1345,6 +1387,10 @@ int audit_filter(int msgtype, unsigned int listtype)
result = audit_comparator(audit_loginuid_set(current),
f->op, f->val);
break;
+ case AUDIT_CONTID:
+ result = audit_comparator64(audit_get_contid(current),
+ f->op, f->val64);
+ break;
case AUDIT_MSGTYPE:
result = audit_comparator(msgtype, f->op, f->val);
break;
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 3138c88887c7..a658fe775b86 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -629,6 +629,10 @@ static int audit_filter_rules(struct task_struct *tsk,
result = audit_comparator(ctx->sockaddr->ss_family,
f->op, f->val);
break;
+ case AUDIT_CONTID:
+ result = audit_comparator64(audit_get_contid(tsk),
+ f->op, f->val64);
+ break;
case AUDIT_SUBJ_USER:
case AUDIT_SUBJ_ROLE:
case AUDIT_SUBJ_TYPE:
--
1.8.3.1

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