[PATCH 0/2] More strict error checking in bpf_asm (v2).

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3 messages, 1 author, 2021-02-24 · open the first message on its own page

[PATCH 0/2] More strict error checking in bpf_asm (v2).

From: Ian Denhardt <hidden>
Date: 2021-02-24 21:23:58

Second pass at the patches from:

https://lore.kernel.org/bpf/ef747c45-a68c-2a87-202c-5fd9faf70392@iogearbox.net/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

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

From: Ian Denhardt <hidden>
Date: 2021-02-24 21:23:34

Per discussion at:

https://lore.kernel.org/bpf/c964892195a6b91d20a67691448567ef528ffa6d.camel@linux.ibm.com/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 <iii@linux.ibm.com>
Signed-off-by: Ian Denhradt <redacted>
---
 tools/bpf/bpf_exp.y | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/bpf/bpf_exp.y b/tools/bpf/bpf_exp.y
index 8d48e896be50..8d03e5245da5 100644
--- a/tools/bpf/bpf_exp.y
+++ b/tools/bpf/bpf_exp.y

@@ -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;
 }

-- 
2.30.1

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

From: Ian Denhardt <hidden>
Date: 2021-02-24 21:23:53

...so callers can correctly detect failure.

Signed-off-by: Ian Denhardt <redacted>
---
 tools/bpf/bpf_exp.y | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/bpf/bpf_exp.y b/tools/bpf/bpf_exp.y
index 8d03e5245da5..dfb7254a24e8 100644
--- a/tools/bpf/bpf_exp.y
+++ b/tools/bpf/bpf_exp.y

@@ -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;

-- 
2.30.1

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