net: filter: get rid of BPF_S_* enum

This patch finally allows us to get rid of the BPF_S_* enum.
Currently, the code performs unnecessary encode and decode
workarounds in seccomp and filter migration itself when a filter
is being attached in order to overcome BPF_S_* encoding which
is not used anymore by the new interpreter resp. JIT compilers.

Keeping it around would mean that also in future we would need
to extend and maintain this enum and related encoders/decoders.
We can get rid of all that and save us these operations during
filter attaching. Naturally, also JIT compilers need to be updated
by this.

Before JIT conversion is being done, each compiler checks if A
is being loaded at startup to obtain information if it needs to
emit instructions to clear A first. Since BPF extensions are a
subset of BPF_LD | BPF_{W,H,B} | BPF_ABS variants, case statements
for extensions can be removed at that point. To ease and minimalize
code changes in the classic JITs, we have introduced bpf_anc_helper().

Tested with test_bpf on x86_64 (JIT, int), s390x (JIT, int),
arm (JIT, int), i368 (int), ppc64 (JIT, int); for sparc we
unfortunately didn't have access, but changes are analogous to
the rest.

Joint work with Alexei Starovoitov.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Mircea Gherzan <mgherzan@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Acked-by: Chema Gonzalez <chemag@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 38 insertions, 70 deletions

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 625f4de..49ef7a2 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -197,7 +197,6 @@ int sk_detach_filter(struct sock *sk);
 int sk_chk_filter(struct sock_filter *filter, unsigned int flen);
 int sk_get_filter(struct sock *sk, struct sock_filter __user *filter,
 		  unsigned int len);
-void sk_decode_filter(struct sock_filter *filt, struct sock_filter *to);
 
 void sk_filter_charge(struct sock *sk, struct sk_filter *fp);
 void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp);
@@ -205,6 +204,41 @@ void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp);
 u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
 void bpf_int_jit_compile(struct sk_filter *fp);
 
+#define BPF_ANC		BIT(15)
+
+static inline u16 bpf_anc_helper(const struct sock_filter *ftest)
+{
+	BUG_ON(ftest->code & BPF_ANC);
+
+	switch (ftest->code) {
+	case BPF_LD | BPF_W | BPF_ABS:
+	case BPF_LD | BPF_H | BPF_ABS:
+	case BPF_LD | BPF_B | BPF_ABS:
+#define BPF_ANCILLARY(CODE)	case SKF_AD_OFF + SKF_AD_##CODE:	\
+				return BPF_ANC | SKF_AD_##CODE
+		switch (ftest->k) {
+		BPF_ANCILLARY(PROTOCOL);
+		BPF_ANCILLARY(PKTTYPE);
+		BPF_ANCILLARY(IFINDEX);
+		BPF_ANCILLARY(NLATTR);
+		BPF_ANCILLARY(NLATTR_NEST);
+		BPF_ANCILLARY(MARK);
+		BPF_ANCILLARY(QUEUE);
+		BPF_ANCILLARY(HATYPE);
+		BPF_ANCILLARY(RXHASH);
+		BPF_ANCILLARY(CPU);
+		BPF_ANCILLARY(ALU_XOR_X);
+		BPF_ANCILLARY(VLAN_TAG);
+		BPF_ANCILLARY(VLAN_TAG_PRESENT);
+		BPF_ANCILLARY(PAY_OFFSET);
+		BPF_ANCILLARY(RANDOM);
+		}
+		/* Fallthrough. */
+	default:
+		return ftest->code;
+	}
+}
+
 #ifdef CONFIG_BPF_JIT
 #include <stdarg.h>
 #include <linux/linkage.h>
@@ -224,86 +258,20 @@ static inline void bpf_jit_dump(unsigned int flen, unsigned int proglen,
 }
 #else
 #include <linux/slab.h>
+
 static inline void bpf_jit_compile(struct sk_filter *fp)
 {
 }
+
 static inline void bpf_jit_free(struct sk_filter *fp)
 {
 	kfree(fp);
 }
-#endif
+#endif /* CONFIG_BPF_JIT */
 
 static inline int bpf_tell_extensions(void)
 {
 	return SKF_AD_MAX;
 }
 
-enum {
-	BPF_S_RET_K = 1,
-	BPF_S_RET_A,
-	BPF_S_ALU_ADD_K,
-	BPF_S_ALU_ADD_X,
-	BPF_S_ALU_SUB_K,
-	BPF_S_ALU_SUB_X,
-	BPF_S_ALU_MUL_K,
-	BPF_S_ALU_MUL_X,
-	BPF_S_ALU_DIV_X,
-	BPF_S_ALU_MOD_K,
-	BPF_S_ALU_MOD_X,
-	BPF_S_ALU_AND_K,
-	BPF_S_ALU_AND_X,
-	BPF_S_ALU_OR_K,
-	BPF_S_ALU_OR_X,
-	BPF_S_ALU_XOR_K,
-	BPF_S_ALU_XOR_X,
-	BPF_S_ALU_LSH_K,
-	BPF_S_ALU_LSH_X,
-	BPF_S_ALU_RSH_K,
-	BPF_S_ALU_RSH_X,
-	BPF_S_ALU_NEG,
-	BPF_S_LD_W_ABS,
-	BPF_S_LD_H_ABS,
-	BPF_S_LD_B_ABS,
-	BPF_S_LD_W_LEN,
-	BPF_S_LD_W_IND,
-	BPF_S_LD_H_IND,
-	BPF_S_LD_B_IND,
-	BPF_S_LD_IMM,
-	BPF_S_LDX_W_LEN,
-	BPF_S_LDX_B_MSH,
-	BPF_S_LDX_IMM,
-	BPF_S_MISC_TAX,
-	BPF_S_MISC_TXA,
-	BPF_S_ALU_DIV_K,
-	BPF_S_LD_MEM,
-	BPF_S_LDX_MEM,
-	BPF_S_ST,
-	BPF_S_STX,
-	BPF_S_JMP_JA,
-	BPF_S_JMP_JEQ_K,
-	BPF_S_JMP_JEQ_X,
-	BPF_S_JMP_JGE_K,
-	BPF_S_JMP_JGE_X,
-	BPF_S_JMP_JGT_K,
-	BPF_S_JMP_JGT_X,
-	BPF_S_JMP_JSET_K,
-	BPF_S_JMP_JSET_X,
-	/* Ancillary data */
-	BPF_S_ANC_PROTOCOL,
-	BPF_S_ANC_PKTTYPE,
-	BPF_S_ANC_IFINDEX,
-	BPF_S_ANC_NLATTR,
-	BPF_S_ANC_NLATTR_NEST,
-	BPF_S_ANC_MARK,
-	BPF_S_ANC_QUEUE,
-	BPF_S_ANC_HATYPE,
-	BPF_S_ANC_RXHASH,
-	BPF_S_ANC_CPU,
-	BPF_S_ANC_ALU_XOR_X,
-	BPF_S_ANC_VLAN_TAG,
-	BPF_S_ANC_VLAN_TAG_PRESENT,
-	BPF_S_ANC_PAY_OFFSET,
-	BPF_S_ANC_RANDOM,
-};
-
 #endif /* __LINUX_FILTER_H__ */