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More strict error checking in bpf_asm (v2).

PATCH New Ian Denhardt 1 participant 3 messages Feb 24, 2021

Subsystems (3)
Networking Network drivers BPF
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Ian Denhardt

author
#0 lore raw

cover More strict error checking in bpf_asm (v2).

Second pass at the patches from:

https://lore.kernel.org/bpf/[email protected]/T/#t.

Patches are the same, this just addes the Signed-off-by: lines as requested by Daniel Borkmann

Ian Denhardt (2):
tools, bpf_asm: Hard error on out of range jumps. tools, bpf_asm: exit non-zero on errors.

 tools/bpf/bpf_exp.y | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

--
2.30.1

author
#1 lore raw

PATCH 1/2 tools, bpf_asm: Hard error on out of range jumps.

Per discussion at:

https://lore.kernel.org/bpf/[email protected]/T/#t

...this was originally introduced as a warning due to concerns about breaking existing code, but a hard error probably makes more sense, especially given that concerns about breakage were only speculation.

Acked-by Ilya Leoshkevich <[email protected]>
Signed-off-by Ian Denhradt <[email protected]>
---
 tools/bpf/bpf_exp.y | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
tools/bpf/bpf_exp.y +4 -2
index 8d48e896be50..8d03e5245da5 100644
@@ -549,9 +549,11 @@ static uint8_t bpf_encode_jt_jf_offset(int off, int i)
 {
 	int delta = off - i - 1;
 
-	if (delta < 0 || delta > 255)
-		fprintf(stderr, "warning: insn #%d jumps to insn #%d, "
+	if (delta < 0 || delta > 255) {
+		fprintf(stderr, "error: insn #%d jumps to insn #%d, "
 				"which is out of range\n", i, off);
+		exit(1);
+	}
 	return (uint8_t) delta;
 }
Signature · 1 line
2.30.1
author
#2 lore raw

PATCH 2/2 tools, bpf_asm: exit non-zero on errors.

In reply to Ian Denhardt

...so callers can correctly detect failure.

Signed-off-by Ian Denhardt <[email protected]>
---
 tools/bpf/bpf_exp.y | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
tools/bpf/bpf_exp.y +4 -4
index 8d03e5245da5..dfb7254a24e8 100644
@@ -185,13 +185,13 @@ ldx
 	| OP_LDXB number '*' '(' '[' number ']' '&' number ')' {
 		if ($2 != 4 || $9 != 0xf) {
 			fprintf(stderr, "ldxb offset not supported!\n");
-			exit(0);
+			exit(1);
 		} else {
 			bpf_set_curr_instr(BPF_LDX | BPF_MSH | BPF_B, 0, 0, $6); } }
 	| OP_LDX number '*' '(' '[' number ']' '&' number ')' {
 		if ($2 != 4 || $9 != 0xf) {
 			fprintf(stderr, "ldxb offset not supported!\n");
-			exit(0);
+			exit(1);
 		} else {
 			bpf_set_curr_instr(BPF_LDX | BPF_MSH | BPF_B, 0, 0, $6); } }
 	;

@@ -472,7 +472,7 @@ static void bpf_assert_max(void)
 {
 	if (curr_instr >= BPF_MAXINSNS) {
 		fprintf(stderr, "only max %u insns allowed!\n", BPF_MAXINSNS);
-		exit(0);
+		exit(1);
 	}
 }
 

@@ -522,7 +522,7 @@ static int bpf_find_insns_offset(const char *label)
 
 	if (ret == -ENOENT) {
 		fprintf(stderr, "no such label \'%s\'!\n", label);
-		exit(0);
+		exit(1);
 	}
 
 	return ret;
Signature · 1 line
2.30.1