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authorAlice Frosi <afrosi@redhat.com>2023-04-18 09:26:48 +0200
committerAlice Frosi <afrosi@redhat.com>2023-04-18 09:26:48 +0200
commitafc2ca712ee6bc3b88e763e250dc8aefa8c3fc49 (patch)
treede0972019157e56ab1ef6bcd0fd899f923b79318
parent09fc3f511f7b5579fdc76eb43035c2758661f7f7 (diff)
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filter: add and operation
-rw-r--r--cooker/filter.c66
-rw-r--r--cooker/filter.h1
2 files changed, 57 insertions, 10 deletions
diff --git a/cooker/filter.c b/cooker/filter.c
index 8354ec5..febf3da 100644
--- a/cooker/filter.c
+++ b/cooker/filter.c
@@ -187,17 +187,25 @@ static unsigned int get_n_args_syscall_instr(const struct syscall_entry *table)
continue;
switch (entry->args[k].type) {
case U32:
- /* For 32 bit arguments: 2 instructions,
- * 1 for loading the value and
- * 1 for evaluating the argument */
- n += 2;
+ /* For 32 bit arguments
+ * comparison instructions (2):
+ * 1 loading the value + 1 for evaluation
+ * arithemtic instructions (3):
+ * 1 loading the value + 1 for the operation + 1 for evaluation
+ */
+ if (entry->args[k].cmp == AND_EQ)
+ n += 3;
+ else
+ n += 2;
break;
case U64:
- /* For 64 bit arguments: 4 instructions, for
- * loading and evaluating the high and low 32
- * bits chuncks.
+ /* For 64 bit arguments: 32 instructions * 2
+ * for loading and evaluating the high and low 32 bits chuncks.
*/
- n += 4;
+ if (entry->args[k].cmp == AND_EQ)
+ n += 6;
+ else
+ n += 4;
break;
}
}
@@ -361,6 +369,38 @@ static unsigned int le(struct sock_filter filter[], int idx,
return gt(filter, idx, entry, jfalse, jtrue);
}
+static unsigned int and_eq (struct sock_filter filter[], int idx,
+ const struct bpf_call *entry, unsigned int jtrue,
+ unsigned int jfalse)
+{
+ unsigned int size = 0;
+
+ switch (entry->args[idx].type) {
+ case U64:
+ filter[size++] = (struct sock_filter)LOAD(LO_ARG(idx));
+ filter[size++] = (struct sock_filter)AND(
+ get_lo(entry->args[idx].op2.v64));
+ filter[size++] = (struct sock_filter)EQ(
+ get_lo((entry->args[idx]).value.v64), 0, jfalse);
+ filter[size++] = (struct sock_filter)LOAD(HI_ARG(idx));
+ filter[size++] = (struct sock_filter)AND(
+ get_hi(entry->args[idx].op2.v64));
+ filter[size++] = (struct sock_filter)EQ(
+ get_hi(entry->args[idx].value.v64), jtrue, jfalse);
+ break;
+ case U32:
+
+ filter[size++] = (struct sock_filter)LOAD(LO_ARG(idx));
+ filter[size++] =
+ (struct sock_filter)AND(entry->args[idx].op2.v32);
+ filter[size++] = (struct sock_filter)EQ(
+ entry->args[idx].value.v32, jtrue, jfalse);
+ break;
+ }
+
+ return size;
+}
+
unsigned int create_bfp_program(struct syscall_entry table[],
struct sock_filter filter[],
unsigned int n_syscall)
@@ -467,8 +507,14 @@ unsigned int create_bfp_program(struct syscall_entry table[],
size += le(&filter[size], k, entry, 0,
offset);
break;
- default:
- continue;
+ case AND_EQ:
+ size += and_eq (&filter[size], k, entry,
+ 0, offset);
+ break;
+ case AND_NE:
+ fprintf(stderr,
+ "AND_NE not supported yet\n");
+ break;
}
n_checks++;
has_arg = true;
diff --git a/cooker/filter.h b/cooker/filter.h
index 2729669..0a7d0e0 100644
--- a/cooker/filter.h
+++ b/cooker/filter.h
@@ -33,6 +33,7 @@
#define LT(x, a1, a2) GE((x), (a2), (a1))
#define LE(x, a1, a2) GT((x), (a2), (a1))
#define LOAD(x) BPF_STMT(BPF_LD | BPF_W | BPF_ABS, (x))
+#define AND(x) BPF_STMT(BPF_ALU | BPF_AND | BPF_IMM, (x))
#define MAX_FILTER 1024
#define MAX_JUMPS 128