[PATCH bpf-next v2 1/2] bpftool: Add HELP_SPEC_OPTIONS in token.c

[PATCH bpf-next v2 1/2] bpftool: Add HELP_SPEC_OPTIONS in token.c

[Tao Chen]

$ ./bpftool token help

Usage: bpftool token { show | list }
       bpftool token help
       OPTIONS := { {-j|--json} [{-p|--pretty}] | {-d|--debug} }

Fixes: 2d812311c2b2 ("bpftool: Add bpf_token show")
Acked-by: Quentin Monnet <qmo@kernel.org>
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
---
 tools/bpf/bpftool/token.c | 1 +
 1 file changed, 1 insertion(+)

Change list:
 v1 -> v2:
  - strdup(mntent->mnt_opts) once per cmd/map/prog and
    remove another strdrup/free in print_items_per_line
    in patch2.(Alexei)
  v1: https://lore.kernel.org/bpf/20250916054111.1151487-1-chen.dylane@linux.dev

diff --git a/tools/bpf/bpftool/token.c b/tools/bpf/bpftool/token.c
index 6312e662a12..82b829e44c8 100644
--- a/tools/bpf/bpftool/token.c
+++ b/tools/bpf/bpftool/token.c
@@ -206,6 +206,7 @@ static int do_help(int argc, char **argv)
 	fprintf(stderr,
 		"Usage: %1$s %2$s { show | list }\n"
 		"       %1$s %2$s help\n"
+		"       " HELP_SPEC_OPTIONS " }\n"
 		"\n"
 		"",
 		bin_name, argv[-2]);
-- 
2.48.1

[PATCH bpf-next v2 2/2] bpftool: Fix UAF in get_delegate_value

[Tao Chen]

The return value ret pointer is pointing opts_copy, but opts_copy
gets freed in get_delegate_value before return, fix this by free
the mntent->mnt_opts strdup memory after show delegate value.

Fixes: 2d812311c2b2 ("bpftool: Add bpf_token show")
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
---
 tools/bpf/bpftool/token.c | 75 +++++++++++++++++----------------------
 1 file changed, 33 insertions(+), 42 deletions(-)

diff --git a/tools/bpf/bpftool/token.c b/tools/bpf/bpftool/token.c
index 82b829e44c8..05bc76c7276 100644
--- a/tools/bpf/bpftool/token.c
+++ b/tools/bpf/bpftool/token.c
@@ -28,15 +28,14 @@ static bool has_delegate_options(const char *mnt_ops)
 	       strstr(mnt_ops, "delegate_attachs");
 }
 
-static char *get_delegate_value(const char *opts, const char *key)
+static char *get_delegate_value(char *opts, const char *key)
 {
 	char *token, *rest, *ret = NULL;
-	char *opts_copy = strdup(opts);
 
-	if (!opts_copy)
+	if (!opts)
 		return NULL;
 
-	for (token = strtok_r(opts_copy, ",", &rest); token;
+	for (token = strtok_r(opts, ",", &rest); token;
 			token = strtok_r(NULL, ",", &rest)) {
 		if (strncmp(token, key, strlen(key)) == 0 &&
 		    token[strlen(key)] == '=') {
@@ -44,24 +43,19 @@ static char *get_delegate_value(const char *opts, const char *key)
 			break;
 		}
 	}
-	free(opts_copy);
 
 	return ret;
 }
 
-static void print_items_per_line(const char *input, int items_per_line)
+static void print_items_per_line(char *input, int items_per_line)
 {
-	char *str, *rest, *strs;
+	char *str, *rest;
 	int cnt = 0;
 
 	if (!input)
 		return;
 
-	strs = strdup(input);
-	if (!strs)
-		return;
-
-	for (str = strtok_r(strs, ":", &rest); str;
+	for (str = strtok_r(input, ":", &rest); str;
 			str = strtok_r(NULL, ":", &rest)) {
 		if (cnt % items_per_line == 0)
 			printf("\n\t  ");
@@ -69,38 +63,39 @@ static void print_items_per_line(const char *input, int items_per_line)
 		printf("%-20s", str);
 		cnt++;
 	}
-
-	free(strs);
 }
 
+#define PRINT_DELEGATE_OPT(opt_name) do {		\
+	char *opts, *value;				\
+	opts = strdup(mntent->mnt_opts);		\
+	value = get_delegate_value(opts, opt_name);	\
+	print_items_per_line(value, ITEMS_PER_LINE);	\
+	free(opts);					\
+} while (0)
+
 #define ITEMS_PER_LINE 4
 static void show_token_info_plain(struct mntent *mntent)
 {
-	char *value;
 
 	printf("token_info  %s", mntent->mnt_dir);
 
 	printf("\n\tallowed_cmds:");
-	value = get_delegate_value(mntent->mnt_opts, "delegate_cmds");
-	print_items_per_line(value, ITEMS_PER_LINE);
+	PRINT_DELEGATE_OPT("delegate_cmds");
 
 	printf("\n\tallowed_maps:");
-	value = get_delegate_value(mntent->mnt_opts, "delegate_maps");
-	print_items_per_line(value, ITEMS_PER_LINE);
+	PRINT_DELEGATE_OPT("delegate_maps");
 
 	printf("\n\tallowed_progs:");
-	value = get_delegate_value(mntent->mnt_opts, "delegate_progs");
-	print_items_per_line(value, ITEMS_PER_LINE);
+	PRINT_DELEGATE_OPT("delegate_progs");
 
 	printf("\n\tallowed_attachs:");
-	value = get_delegate_value(mntent->mnt_opts, "delegate_attachs");
-	print_items_per_line(value, ITEMS_PER_LINE);
+	PRINT_DELEGATE_OPT("delegate_attachs");
 	printf("\n");
 }
 
-static void split_json_array_str(const char *input)
+static void split_json_array_str(char *input)
 {
-	char *str, *rest, *strs;
+	char *str, *rest;
 
 	if (!input) {
 		jsonw_start_array(json_wtr);
@@ -108,43 +103,39 @@ static void split_json_array_str(const char *input)
 		return;
 	}
 
-	strs = strdup(input);
-	if (!strs)
-		return;
-
 	jsonw_start_array(json_wtr);
-	for (str = strtok_r(strs, ":", &rest); str;
+	for (str = strtok_r(input, ":", &rest); str;
 			str = strtok_r(NULL, ":", &rest)) {
 		jsonw_string(json_wtr, str);
 	}
 	jsonw_end_array(json_wtr);
-
-	free(strs);
 }
 
+#define PRINT_DELEGATE_OPT_JSON(opt_name) do {		\
+	char *opts, *value;				\
+	opts = strdup(mntent->mnt_opts);		\
+	value = get_delegate_value(opts, opt_name);	\
+	split_json_array_str(value);			\
+	free(opts);					\
+} while (0)
+
 static void show_token_info_json(struct mntent *mntent)
 {
-	char *value;
-
 	jsonw_start_object(json_wtr);
 
 	jsonw_string_field(json_wtr, "token_info", mntent->mnt_dir);
 
 	jsonw_name(json_wtr, "allowed_cmds");
-	value = get_delegate_value(mntent->mnt_opts, "delegate_cmds");
-	split_json_array_str(value);
+	PRINT_DELEGATE_OPT_JSON("delegate_cmds");
 
 	jsonw_name(json_wtr, "allowed_maps");
-	value = get_delegate_value(mntent->mnt_opts, "delegate_maps");
-	split_json_array_str(value);
+	PRINT_DELEGATE_OPT_JSON("delegate_maps");
 
 	jsonw_name(json_wtr, "allowed_progs");
-	value = get_delegate_value(mntent->mnt_opts, "delegate_progs");
-	split_json_array_str(value);
+	PRINT_DELEGATE_OPT_JSON("delegate_progs");
 
 	jsonw_name(json_wtr, "allowed_attachs");
-	value = get_delegate_value(mntent->mnt_opts, "delegate_attachs");
-	split_json_array_str(value);
+	PRINT_DELEGATE_OPT_JSON("delegate_attachs");
 
 	jsonw_end_object(json_wtr);
 }
-- 
2.48.1

Re: [PATCH bpf-next v2 2/2] bpftool: Fix UAF in get_delegate_value

[Quentin Monnet]

2025-09-17 11:47 UTC+0800 ~ Tao Chen <chen.dylane@linux.dev>
> The return value ret pointer is pointing opts_copy, but opts_copy
> gets freed in get_delegate_value before return, fix this by free
> the mntent->mnt_opts strdup memory after show delegate value.
> 
> Fixes: 2d812311c2b2 ("bpftool: Add bpf_token show")
> Signed-off-by: Tao Chen <chen.dylane@linux.dev>
> ---
>  tools/bpf/bpftool/token.c | 75 +++++++++++++++++----------------------
>  1 file changed, 33 insertions(+), 42 deletions(-)
> 
> diff --git a/tools/bpf/bpftool/token.c b/tools/bpf/bpftool/token.c
> index 82b829e44c8..05bc76c7276 100644
> --- a/tools/bpf/bpftool/token.c
> +++ b/tools/bpf/bpftool/token.c
> @@ -28,15 +28,14 @@ static bool has_delegate_options(const char *mnt_ops)
>  	       strstr(mnt_ops, "delegate_attachs");
>  }
>  
> -static char *get_delegate_value(const char *opts, const char *key)
> +static char *get_delegate_value(char *opts, const char *key)
>  {
>  	char *token, *rest, *ret = NULL;
> -	char *opts_copy = strdup(opts);
>  
> -	if (!opts_copy)
> +	if (!opts)
>  		return NULL;
>  
> -	for (token = strtok_r(opts_copy, ",", &rest); token;
> +	for (token = strtok_r(opts, ",", &rest); token;
>  			token = strtok_r(NULL, ",", &rest)) {
>  		if (strncmp(token, key, strlen(key)) == 0 &&
>  		    token[strlen(key)] == '=') {
> @@ -44,24 +43,19 @@ static char *get_delegate_value(const char *opts, const char *key)
>  			break;
>  		}
>  	}
> -	free(opts_copy);
>  
>  	return ret;
>  }
>  
> -static void print_items_per_line(const char *input, int items_per_line)
> +static void print_items_per_line(char *input, int items_per_line)
>  {
> -	char *str, *rest, *strs;
> +	char *str, *rest;
>  	int cnt = 0;
>  
>  	if (!input)
>  		return;
>  
> -	strs = strdup(input);
> -	if (!strs)
> -		return;
> -
> -	for (str = strtok_r(strs, ":", &rest); str;
> +	for (str = strtok_r(input, ":", &rest); str;
>  			str = strtok_r(NULL, ":", &rest)) {
>  		if (cnt % items_per_line == 0)
>  			printf("\n\t  ");
> @@ -69,38 +63,39 @@ static void print_items_per_line(const char *input, int items_per_line)
>  		printf("%-20s", str);
>  		cnt++;
>  	}
> -
> -	free(strs);
>  }
>  
> +#define PRINT_DELEGATE_OPT(opt_name) do {		\
> +	char *opts, *value;				\
> +	opts = strdup(mntent->mnt_opts);		\
> +	value = get_delegate_value(opts, opt_name);	\
> +	print_items_per_line(value, ITEMS_PER_LINE);	\
> +	free(opts);					\
> +} while (0)


Thanks! The fix looks OK to me, but why do you need to have
PRINT_DELEGATE_OPT*() as macros? Can't you just use functions instead?

Quentin

Re: [PATCH bpf-next v2 2/2] bpftool: Fix UAF in get_delegate_value

[Andrii Nakryiko]

On Wed, Sep 17, 2025 at 9:30 AM Quentin Monnet <qmo@kernel.org> wrote:
>
> 2025-09-17 11:47 UTC+0800 ~ Tao Chen <chen.dylane@linux.dev>
> > The return value ret pointer is pointing opts_copy, but opts_copy
> > gets freed in get_delegate_value before return, fix this by free
> > the mntent->mnt_opts strdup memory after show delegate value.
> >
> > Fixes: 2d812311c2b2 ("bpftool: Add bpf_token show")
> > Signed-off-by: Tao Chen <chen.dylane@linux.dev>
> > ---
> >  tools/bpf/bpftool/token.c | 75 +++++++++++++++++----------------------
> >  1 file changed, 33 insertions(+), 42 deletions(-)
> >
> > diff --git a/tools/bpf/bpftool/token.c b/tools/bpf/bpftool/token.c
> > index 82b829e44c8..05bc76c7276 100644
> > --- a/tools/bpf/bpftool/token.c
> > +++ b/tools/bpf/bpftool/token.c
> > @@ -28,15 +28,14 @@ static bool has_delegate_options(const char *mnt_ops)
> >              strstr(mnt_ops, "delegate_attachs");
> >  }
> >
> > -static char *get_delegate_value(const char *opts, const char *key)
> > +static char *get_delegate_value(char *opts, const char *key)
> >  {
> >       char *token, *rest, *ret = NULL;
> > -     char *opts_copy = strdup(opts);
> >
> > -     if (!opts_copy)
> > +     if (!opts)
> >               return NULL;
> >
> > -     for (token = strtok_r(opts_copy, ",", &rest); token;
> > +     for (token = strtok_r(opts, ",", &rest); token;
> >                       token = strtok_r(NULL, ",", &rest)) {
> >               if (strncmp(token, key, strlen(key)) == 0 &&
> >                   token[strlen(key)] == '=') {
> > @@ -44,24 +43,19 @@ static char *get_delegate_value(const char *opts, const char *key)
> >                       break;
> >               }
> >       }
> > -     free(opts_copy);
> >
> >       return ret;
> >  }
> >
> > -static void print_items_per_line(const char *input, int items_per_line)
> > +static void print_items_per_line(char *input, int items_per_line)
> >  {
> > -     char *str, *rest, *strs;
> > +     char *str, *rest;
> >       int cnt = 0;
> >
> >       if (!input)
> >               return;
> >
> > -     strs = strdup(input);
> > -     if (!strs)
> > -             return;
> > -
> > -     for (str = strtok_r(strs, ":", &rest); str;
> > +     for (str = strtok_r(input, ":", &rest); str;
> >                       str = strtok_r(NULL, ":", &rest)) {
> >               if (cnt % items_per_line == 0)
> >                       printf("\n\t  ");
> > @@ -69,38 +63,39 @@ static void print_items_per_line(const char *input, int items_per_line)
> >               printf("%-20s", str);
> >               cnt++;
> >       }
> > -
> > -     free(strs);
> >  }
> >
> > +#define PRINT_DELEGATE_OPT(opt_name) do {            \
> > +     char *opts, *value;                             \
> > +     opts = strdup(mntent->mnt_opts);                \
> > +     value = get_delegate_value(opts, opt_name);     \
> > +     print_items_per_line(value, ITEMS_PER_LINE);    \
> > +     free(opts);                                     \
> > +} while (0)
>
>
> Thanks! The fix looks OK to me, but why do you need to have
> PRINT_DELEGATE_OPT*() as macros? Can't you just use functions instead?

right, function or just a loop, that will allow to also avoid
repeating jsonw_name or printf calls:

struct { const char *header, key; } sets = {
    {"allowed_cmds", "delegate_cmds"},
    {"allowed_maps", "delegate_maps"},
    ...
};

for (i = 0; i < ARRAY_SIZE(sets); i++) {
    ... use sets[i].header and sets[i].key ...
}

pw-bot: cr

>
> Quentin

Re: [PATCH bpf-next v2 2/2] bpftool: Fix UAF in get_delegate_value

[Tao Chen]

在 2025/9/18 00:30, Quentin Monnet 写道:
> 2025-09-17 11:47 UTC+0800 ~ Tao Chen <chen.dylane@linux.dev>
>> The return value ret pointer is pointing opts_copy, but opts_copy
>> gets freed in get_delegate_value before return, fix this by free
>> the mntent->mnt_opts strdup memory after show delegate value.
>>
>> Fixes: 2d812311c2b2 ("bpftool: Add bpf_token show")
>> Signed-off-by: Tao Chen <chen.dylane@linux.dev>
>> ---
>>   tools/bpf/bpftool/token.c | 75 +++++++++++++++++----------------------
>>   1 file changed, 33 insertions(+), 42 deletions(-)
>>
>> diff --git a/tools/bpf/bpftool/token.c b/tools/bpf/bpftool/token.c
>> index 82b829e44c8..05bc76c7276 100644
>> --- a/tools/bpf/bpftool/token.c
>> +++ b/tools/bpf/bpftool/token.c
>> @@ -28,15 +28,14 @@ static bool has_delegate_options(const char *mnt_ops)
>>   	       strstr(mnt_ops, "delegate_attachs");
>>   }
>>   
>> -static char *get_delegate_value(const char *opts, const char *key)
>> +static char *get_delegate_value(char *opts, const char *key)
>>   {
>>   	char *token, *rest, *ret = NULL;
>> -	char *opts_copy = strdup(opts);
>>   
>> -	if (!opts_copy)
>> +	if (!opts)
>>   		return NULL;
>>   
>> -	for (token = strtok_r(opts_copy, ",", &rest); token;
>> +	for (token = strtok_r(opts, ",", &rest); token;
>>   			token = strtok_r(NULL, ",", &rest)) {
>>   		if (strncmp(token, key, strlen(key)) == 0 &&
>>   		    token[strlen(key)] == '=') {
>> @@ -44,24 +43,19 @@ static char *get_delegate_value(const char *opts, const char *key)
>>   			break;
>>   		}
>>   	}
>> -	free(opts_copy);
>>   
>>   	return ret;
>>   }
>>   
>> -static void print_items_per_line(const char *input, int items_per_line)
>> +static void print_items_per_line(char *input, int items_per_line)
>>   {
>> -	char *str, *rest, *strs;
>> +	char *str, *rest;
>>   	int cnt = 0;
>>   
>>   	if (!input)
>>   		return;
>>   
>> -	strs = strdup(input);
>> -	if (!strs)
>> -		return;
>> -
>> -	for (str = strtok_r(strs, ":", &rest); str;
>> +	for (str = strtok_r(input, ":", &rest); str;
>>   			str = strtok_r(NULL, ":", &rest)) {
>>   		if (cnt % items_per_line == 0)
>>   			printf("\n\t  ");
>> @@ -69,38 +63,39 @@ static void print_items_per_line(const char *input, int items_per_line)
>>   		printf("%-20s", str);
>>   		cnt++;
>>   	}
>> -
>> -	free(strs);
>>   }
>>   
>> +#define PRINT_DELEGATE_OPT(opt_name) do {		\
>> +	char *opts, *value;				\
>> +	opts = strdup(mntent->mnt_opts);		\
>> +	value = get_delegate_value(opts, opt_name);	\
>> +	print_items_per_line(value, ITEMS_PER_LINE);	\
>> +	free(opts);					\
>> +} while (0)
> 
> 
> Thanks! The fix looks OK to me, but why do you need to have
> PRINT_DELEGATE_OPT*() as macros? Can't you just use functions instead?
> 
> Quentin

Well, actually, there is no special purpose about using macros, i will
use functions as you and Andrri suggested, thanks.

-- 
Best Regards
Tao Chen