Re: [iproute PATCH] bpf: Make bytecode-file reading a little more robust

[Stephen Hemminger]

On Wed,  2 Aug 2017 14:57:56 +0200
Phil Sutter  wrote:

> bpf_parse_string() will now correctly handle:
> 
> - Extraneous whitespace,
> - OPs on multiple lines and
> - overlong file names.
> 
> The added feature of allowing to have OPs on multiple lines (like e.g.
> tcpdump prints them) is rather a side effect of fixing detection of
> malformed bytecode files having random content on a second line, like
> e.g.:
> 
> | 4,40 0 0 12,21 0 1 2048,6 0 0 262144,6 0 0 0
> | foobar
> 
> Cc: Daniel Borkmann 
> Signed-off-by: Phil Sutter 

Looks good applied.

Re: [iproute PATCH] bpf: Make bytecode-file reading a little more robust

[Daniel Borkmann]

On 08/02/2017 02:57 PM, Phil Sutter wrote:

bpf_parse_string() will now correctly handle:

- Extraneous whitespace,
- OPs on multiple lines and
- overlong file names.

The added feature of allowing to have OPs on multiple lines (like e.g.
tcpdump prints them) is rather a side effect of fixing detection of
malformed bytecode files having random content on a second line, like
e.g.:

| 4,40 0 0 12,21 0 1 2048,6 0 0 262144,6 0 0 0
| foobar

Cc: Daniel Borkmann 
Signed-off-by: Phil Sutter 


Acked-by: Daniel Borkmann 

[iproute PATCH] bpf: Make bytecode-file reading a little more robust

[Phil Sutter]

bpf_parse_string() will now correctly handle:

- Extraneous whitespace,
- OPs on multiple lines and
- overlong file names.

The added feature of allowing to have OPs on multiple lines (like e.g.
tcpdump prints them) is rather a side effect of fixing detection of
malformed bytecode files having random content on a second line, like
e.g.:

| 4,40 0 0 12,21 0 1 2048,6 0 0 262144,6 0 0 0
| foobar

Cc: Daniel Borkmann 
Signed-off-by: Phil Sutter 
---
 lib/bpf.c | 32 
 1 file changed, 24 insertions(+), 8 deletions(-)

diff --git a/lib/bpf.c b/lib/bpf.c
index e7a4d12fdf2f9..4f52ad4a8f023 100644
--- a/lib/bpf.c
+++ b/lib/bpf.c
@@ -208,11 +208,11 @@ static int bpf_parse_string(char *arg, bool from_file, 
__u16 *bpf_len,
 
if (from_file) {
size_t tmp_len, op_len = sizeof("65535 255 255 4294967295,");
-   char *tmp_string, *last;
+   char *tmp_string, *pos, c, c_prev = ' ';
FILE *fp;
 
tmp_len = sizeof("4096,") + BPF_MAXINSNS * op_len;
-   tmp_string = calloc(1, tmp_len);
+   tmp_string = pos = calloc(1, tmp_len);
if (tmp_string == NULL)
return -ENOMEM;
 
@@ -223,17 +223,33 @@ static int bpf_parse_string(char *arg, bool from_file, 
__u16 *bpf_len,
return -ENOENT;
}
 
-   if (!fgets(tmp_string, tmp_len, fp)) {
+   while ((c = fgetc(fp)) != EOF) {
+   switch (c) {
+   case '\n':
+   if (c_prev != ',')
+   *(pos++) = ',';
+   break;
+   case ' ':
+   case '\t':
+   if (c_prev != ' ')
+   *(pos++) = c;
+   break;
+   default:
+   *(pos++) = c;
+   }
+   if (pos - tmp_string == tmp_len)
+   break;
+   c_prev = c;
+   }
+
+   if (!feof(fp)) {
free(tmp_string);
fclose(fp);
-   return -EIO;
+   return -E2BIG;
}
 
fclose(fp);
-
-   last = _string[strlen(tmp_string) - 1];
-   if (*last == '\n')
-   *last = 0;
+   *pos = 0;
 
*need_release = true;
*bpf_string = tmp_string;
-- 
2.13.1