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, 41 insertions, 42 deletions

diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 1036b6f..44e6948 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -103,60 +103,59 @@ static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
 		u32 k = ftest->k;
 
 		switch (code) {
-		case BPF_S_LD_W_ABS:
+		case BPF_LD | BPF_W | BPF_ABS:
 			ftest->code = BPF_LDX | BPF_W | BPF_ABS;
 			/* 32-bit aligned and not out of bounds. */
 			if (k >= sizeof(struct seccomp_data) || k & 3)
 				return -EINVAL;
 			continue;
-		case BPF_S_LD_W_LEN:
+		case BPF_LD | BPF_W | BPF_LEN:
 			ftest->code = BPF_LD | BPF_IMM;
 			ftest->k = sizeof(struct seccomp_data);
 			continue;
-		case BPF_S_LDX_W_LEN:
+		case BPF_LDX | BPF_W | BPF_LEN:
 			ftest->code = BPF_LDX | BPF_IMM;
 			ftest->k = sizeof(struct seccomp_data);
 			continue;
 		/* Explicitly include allowed calls. */
-		case BPF_S_RET_K:
-		case BPF_S_RET_A:
-		case BPF_S_ALU_ADD_K:
-		case BPF_S_ALU_ADD_X:
-		case BPF_S_ALU_SUB_K:
-		case BPF_S_ALU_SUB_X:
-		case BPF_S_ALU_MUL_K:
-		case BPF_S_ALU_MUL_X:
-		case BPF_S_ALU_DIV_X:
-		case BPF_S_ALU_AND_K:
-		case BPF_S_ALU_AND_X:
-		case BPF_S_ALU_OR_K:
-		case BPF_S_ALU_OR_X:
-		case BPF_S_ALU_XOR_K:
-		case BPF_S_ALU_XOR_X:
-		case BPF_S_ALU_LSH_K:
-		case BPF_S_ALU_LSH_X:
-		case BPF_S_ALU_RSH_K:
-		case BPF_S_ALU_RSH_X:
-		case BPF_S_ALU_NEG:
-		case BPF_S_LD_IMM:
-		case BPF_S_LDX_IMM:
-		case BPF_S_MISC_TAX:
-		case BPF_S_MISC_TXA:
-		case BPF_S_ALU_DIV_K:
-		case BPF_S_LD_MEM:
-		case BPF_S_LDX_MEM:
-		case BPF_S_ST:
-		case BPF_S_STX:
-		case BPF_S_JMP_JA:
-		case BPF_S_JMP_JEQ_K:
-		case BPF_S_JMP_JEQ_X:
-		case BPF_S_JMP_JGE_K:
-		case BPF_S_JMP_JGE_X:
-		case BPF_S_JMP_JGT_K:
-		case BPF_S_JMP_JGT_X:
-		case BPF_S_JMP_JSET_K:
-		case BPF_S_JMP_JSET_X:
-			sk_decode_filter(ftest, ftest);
+		case BPF_RET | BPF_K:
+		case BPF_RET | BPF_A:
+		case BPF_ALU | BPF_ADD | BPF_K:
+		case BPF_ALU | BPF_ADD | BPF_X:
+		case BPF_ALU | BPF_SUB | BPF_K:
+		case BPF_ALU | BPF_SUB | BPF_X:
+		case BPF_ALU | BPF_MUL | BPF_K:
+		case BPF_ALU | BPF_MUL | BPF_X:
+		case BPF_ALU | BPF_DIV | BPF_K:
+		case BPF_ALU | BPF_DIV | BPF_X:
+		case BPF_ALU | BPF_AND | BPF_K:
+		case BPF_ALU | BPF_AND | BPF_X:
+		case BPF_ALU | BPF_OR | BPF_K:
+		case BPF_ALU | BPF_OR | BPF_X:
+		case BPF_ALU | BPF_XOR | BPF_K:
+		case BPF_ALU | BPF_XOR | BPF_X:
+		case BPF_ALU | BPF_LSH | BPF_K:
+		case BPF_ALU | BPF_LSH | BPF_X:
+		case BPF_ALU | BPF_RSH | BPF_K:
+		case BPF_ALU | BPF_RSH | BPF_X:
+		case BPF_ALU | BPF_NEG:
+		case BPF_LD | BPF_IMM:
+		case BPF_LDX | BPF_IMM:
+		case BPF_MISC | BPF_TAX:
+		case BPF_MISC | BPF_TXA:
+		case BPF_LD | BPF_MEM:
+		case BPF_LDX | BPF_MEM:
+		case BPF_ST:
+		case BPF_STX:
+		case BPF_JMP | BPF_JA:
+		case BPF_JMP | BPF_JEQ | BPF_K:
+		case BPF_JMP | BPF_JEQ | BPF_X:
+		case BPF_JMP | BPF_JGE | BPF_K:
+		case BPF_JMP | BPF_JGE | BPF_X:
+		case BPF_JMP | BPF_JGT | BPF_K:
+		case BPF_JMP | BPF_JGT | BPF_X:
+		case BPF_JMP | BPF_JSET | BPF_K:
+		case BPF_JMP | BPF_JSET | BPF_X:
 			continue;
 		default:
 			return -EINVAL;