[PATCH bpf] tools: bpftool: JIT limited misreported as negative value on aarch64

[PATCH bpf] tools: bpftool: JIT limited misreported as negative value on aarch64

[Alan Maguire]

On aarch64, "bpftool feature" reports an incorrect BPF JIT limit:

$ sudo /sbin/bpftool feature
Scanning system configuration...
bpf() syscall restricted to privileged users
JIT compiler is enabled
JIT compiler hardening is disabled
JIT compiler kallsyms exports are enabled for root
skipping kernel config, can't open file: No such file or directory
Global memory limit for JIT compiler for unprivileged users is -201326592 bytes

This is because /proc/sys/net/core/bpf_jit_limit reports

$ sudo cat /proc/sys/net/core/bpf_jit_limit
68169519595520

...and an int is assumed in read_procfs().  Change read_procfs()
to return a long to avoid negative value reporting.

Fixes: 7a4522bbef0c ("tools: bpftool: add probes for /proc/ eBPF parameters")
Reported-by: Nicky Veitch <nicky.veitch@oracle.com>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
---
 tools/bpf/bpftool/feature.c | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c
index da16e6a27ccc..0675d6a46413 100644
--- a/tools/bpf/bpftool/feature.c
+++ b/tools/bpf/bpftool/feature.c
@@ -167,12 +167,12 @@ static int get_vendor_id(int ifindex)
 	return strtol(buf, NULL, 0);
 }
 
-static int read_procfs(const char *path)
+static long read_procfs(const char *path)
 {
 	char *endptr, *line = NULL;
 	size_t len = 0;
 	FILE *fd;
-	int res;
+	long res;
 
 	fd = fopen(path, "r");
 	if (!fd)
@@ -194,7 +194,7 @@ static int read_procfs(const char *path)
 
 static void probe_unprivileged_disabled(void)
 {
-	int res;
+	long res;
 
 	/* No support for C-style ouptut */
 
@@ -216,14 +216,14 @@ static void probe_unprivileged_disabled(void)
 			printf("Unable to retrieve required privileges for bpf() syscall\n");
 			break;
 		default:
-			printf("bpf() syscall restriction has unknown value %d\n", res);
+			printf("bpf() syscall restriction has unknown value %ld\n", res);
 		}
 	}
 }
 
 static void probe_jit_enable(void)
 {
-	int res;
+	long res;
 
 	/* No support for C-style ouptut */
 
@@ -245,7 +245,7 @@ static void probe_jit_enable(void)
 			printf("Unable to retrieve JIT-compiler status\n");
 			break;
 		default:
-			printf("JIT-compiler status has unknown value %d\n",
+			printf("JIT-compiler status has unknown value %ld\n",
 			       res);
 		}
 	}
@@ -253,7 +253,7 @@ static void probe_jit_enable(void)
 
 static void probe_jit_harden(void)
 {
-	int res;
+	long res;
 
 	/* No support for C-style ouptut */
 
@@ -275,7 +275,7 @@ static void probe_jit_harden(void)
 			printf("Unable to retrieve JIT hardening status\n");
 			break;
 		default:
-			printf("JIT hardening status has unknown value %d\n",
+			printf("JIT hardening status has unknown value %ld\n",
 			       res);
 		}
 	}
@@ -283,7 +283,7 @@ static void probe_jit_harden(void)
 
 static void probe_jit_kallsyms(void)
 {
-	int res;
+	long res;
 
 	/* No support for C-style ouptut */
 
@@ -302,14 +302,14 @@ static void probe_jit_kallsyms(void)
 			printf("Unable to retrieve JIT kallsyms export status\n");
 			break;
 		default:
-			printf("JIT kallsyms exports status has unknown value %d\n", res);
+			printf("JIT kallsyms exports status has unknown value %ld\n", res);
 		}
 	}
 }
 
 static void probe_jit_limit(void)
 {
-	int res;
+	long res;
 
 	/* No support for C-style ouptut */
 
@@ -322,7 +322,7 @@ static void probe_jit_limit(void)
 			printf("Unable to retrieve global memory limit for JIT compiler for unprivileged users\n");
 			break;
 		default:
-			printf("Global memory limit for JIT compiler for unprivileged users is %d bytes\n", res);
+			printf("Global memory limit for JIT compiler for unprivileged users is %ld bytes\n", res);
 		}
 	}
 }
-- 
2.31.1

Re: [PATCH bpf] tools: bpftool: JIT limited misreported as negative value on aarch64

[Jiri Olsa]

On Fri, May 12, 2023 at 12:31:34PM +0100, Alan Maguire wrote:
> On aarch64, "bpftool feature" reports an incorrect BPF JIT limit:
> 
> $ sudo /sbin/bpftool feature
> Scanning system configuration...
> bpf() syscall restricted to privileged users
> JIT compiler is enabled
> JIT compiler hardening is disabled
> JIT compiler kallsyms exports are enabled for root
> skipping kernel config, can't open file: No such file or directory
> Global memory limit for JIT compiler for unprivileged users is -201326592 bytes
> 
> This is because /proc/sys/net/core/bpf_jit_limit reports
> 
> $ sudo cat /proc/sys/net/core/bpf_jit_limit
> 68169519595520
> 
> ...and an int is assumed in read_procfs().  Change read_procfs()
> to return a long to avoid negative value reporting.
> 
> Fixes: 7a4522bbef0c ("tools: bpftool: add probes for /proc/ eBPF parameters")
> Reported-by: Nicky Veitch <nicky.veitch@oracle.com>
> Signed-off-by: Alan Maguire <alan.maguire@oracle.com>

Acked-by: Jiri Olsa <jolsa@kernel.org>

jirka

> ---
>  tools/bpf/bpftool/feature.c | 24 ++++++++++++------------
>  1 file changed, 12 insertions(+), 12 deletions(-)
> 
> diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c
> index da16e6a27ccc..0675d6a46413 100644
> --- a/tools/bpf/bpftool/feature.c
> +++ b/tools/bpf/bpftool/feature.c
> @@ -167,12 +167,12 @@ static int get_vendor_id(int ifindex)
>  	return strtol(buf, NULL, 0);
>  }
>  
> -static int read_procfs(const char *path)
> +static long read_procfs(const char *path)
>  {
>  	char *endptr, *line = NULL;
>  	size_t len = 0;
>  	FILE *fd;
> -	int res;
> +	long res;
>  
>  	fd = fopen(path, "r");
>  	if (!fd)
> @@ -194,7 +194,7 @@ static int read_procfs(const char *path)
>  
>  static void probe_unprivileged_disabled(void)
>  {
> -	int res;
> +	long res;
>  
>  	/* No support for C-style ouptut */
>  
> @@ -216,14 +216,14 @@ static void probe_unprivileged_disabled(void)
>  			printf("Unable to retrieve required privileges for bpf() syscall\n");
>  			break;
>  		default:
> -			printf("bpf() syscall restriction has unknown value %d\n", res);
> +			printf("bpf() syscall restriction has unknown value %ld\n", res);
>  		}
>  	}
>  }
>  
>  static void probe_jit_enable(void)
>  {
> -	int res;
> +	long res;
>  
>  	/* No support for C-style ouptut */
>  
> @@ -245,7 +245,7 @@ static void probe_jit_enable(void)
>  			printf("Unable to retrieve JIT-compiler status\n");
>  			break;
>  		default:
> -			printf("JIT-compiler status has unknown value %d\n",
> +			printf("JIT-compiler status has unknown value %ld\n",
>  			       res);
>  		}
>  	}
> @@ -253,7 +253,7 @@ static void probe_jit_enable(void)
>  
>  static void probe_jit_harden(void)
>  {
> -	int res;
> +	long res;
>  
>  	/* No support for C-style ouptut */
>  
> @@ -275,7 +275,7 @@ static void probe_jit_harden(void)
>  			printf("Unable to retrieve JIT hardening status\n");
>  			break;
>  		default:
> -			printf("JIT hardening status has unknown value %d\n",
> +			printf("JIT hardening status has unknown value %ld\n",
>  			       res);
>  		}
>  	}
> @@ -283,7 +283,7 @@ static void probe_jit_harden(void)
>  
>  static void probe_jit_kallsyms(void)
>  {
> -	int res;
> +	long res;
>  
>  	/* No support for C-style ouptut */
>  
> @@ -302,14 +302,14 @@ static void probe_jit_kallsyms(void)
>  			printf("Unable to retrieve JIT kallsyms export status\n");
>  			break;
>  		default:
> -			printf("JIT kallsyms exports status has unknown value %d\n", res);
> +			printf("JIT kallsyms exports status has unknown value %ld\n", res);
>  		}
>  	}
>  }
>  
>  static void probe_jit_limit(void)
>  {
> -	int res;
> +	long res;
>  
>  	/* No support for C-style ouptut */
>  
> @@ -322,7 +322,7 @@ static void probe_jit_limit(void)
>  			printf("Unable to retrieve global memory limit for JIT compiler for unprivileged users\n");
>  			break;
>  		default:
> -			printf("Global memory limit for JIT compiler for unprivileged users is %d bytes\n", res);
> +			printf("Global memory limit for JIT compiler for unprivileged users is %ld bytes\n", res);
>  		}
>  	}
>  }
> -- 
> 2.31.1
> 

Re: [PATCH bpf] tools: bpftool: JIT limited misreported as negative value on aarch64

[Quentin Monnet]

2023-05-12 13:58 UTC+0200 ~ Jiri Olsa <olsajiri@gmail.com>
> On Fri, May 12, 2023 at 12:31:34PM +0100, Alan Maguire wrote:
>> On aarch64, "bpftool feature" reports an incorrect BPF JIT limit:
>>
>> $ sudo /sbin/bpftool feature
>> Scanning system configuration...
>> bpf() syscall restricted to privileged users
>> JIT compiler is enabled
>> JIT compiler hardening is disabled
>> JIT compiler kallsyms exports are enabled for root
>> skipping kernel config, can't open file: No such file or directory
>> Global memory limit for JIT compiler for unprivileged users is -201326592 bytes
>>
>> This is because /proc/sys/net/core/bpf_jit_limit reports
>>
>> $ sudo cat /proc/sys/net/core/bpf_jit_limit
>> 68169519595520
>>
>> ...and an int is assumed in read_procfs().  Change read_procfs()
>> to return a long to avoid negative value reporting.
>>
>> Fixes: 7a4522bbef0c ("tools: bpftool: add probes for /proc/ eBPF parameters")
>> Reported-by: Nicky Veitch <nicky.veitch@oracle.com>
>> Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
> 
> Acked-by: Jiri Olsa <jolsa@kernel.org>
> 
> jirka

Acked-by: Quentin Monnet <quentin@isovalent.com>

Thanks!

Re: [PATCH bpf] tools: bpftool: JIT limited misreported as negative value on aarch64

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Daniel Borkmann <daniel@iogearbox.net>:

On Fri, 12 May 2023 12:31:34 +0100 you wrote:
> On aarch64, "bpftool feature" reports an incorrect BPF JIT limit:
> 
> $ sudo /sbin/bpftool feature
> Scanning system configuration...
> bpf() syscall restricted to privileged users
> JIT compiler is enabled
> JIT compiler hardening is disabled
> JIT compiler kallsyms exports are enabled for root
> skipping kernel config, can't open file: No such file or directory
> Global memory limit for JIT compiler for unprivileged users is -201326592 bytes
> 
> [...]

Here is the summary with links:
  - [bpf] tools: bpftool: JIT limited misreported as negative value on aarch64
    https://git.kernel.org/bpf/bpf-next/c/04cb8453a91c

You are awesome, thank you!
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