On Tue, Mar 8, 2022 at 11:55 AM Christian Göttsche
<cgzones@xxxxxxxxxxxxxx> wrote:
>
> The arrays for the policy capability names, the initial sid identifiers
> and the class and permission names are not changed at runtime. Declare
> them const to avoid accidental modification.
>
> Do not override the classmap and the initial sid list in the build time
> script genheaders, by using a static buffer in the conversion function
> stoupperx(). In cases we need to compare or print more than one
> identifier allocate a temporary copy.
>
> Signed-off-by: Christian Göttsche <cgzones@xxxxxxxxxxxxxx>
> ---
> v2:
> Drop const exemption for genheaders script by rewriting stoupperx().
> ---
> scripts/selinux/genheaders/genheaders.c | 76 ++++++++++---------
> scripts/selinux/mdp/mdp.c | 4 +-
> security/selinux/avc.c | 2 +-
> security/selinux/include/avc_ss.h | 2 +-
> security/selinux/include/classmap.h | 2 +-
> .../selinux/include/initial_sid_to_string.h | 3 +-
> security/selinux/include/policycap.h | 2 +-
> security/selinux/include/policycap_names.h | 2 +-
> security/selinux/ss/services.c | 4 +-
> 9 files changed, 51 insertions(+), 46 deletions(-)
>
> diff --git a/scripts/selinux/genheaders/genheaders.c b/scripts/selinux/genheaders/genheaders.c
> index f355b3e0e968..a2caff3c997f 100644
> --- a/scripts/selinux/genheaders/genheaders.c
> +++ b/scripts/selinux/genheaders/genheaders.c
> @@ -26,19 +26,23 @@ static void usage(void)
> exit(1);
> }
>
> -static char *stoupperx(const char *s)
> +static const char *stoupperx(const char *s)
> {
> - char *s2 = strdup(s);
> - char *p;
> + static char buffer[256];
> + unsigned int i;
> + char *p = buffer;
>
> - if (!s2) {
> - fprintf(stderr, "%s: out of memory\n", progname);
> + for (i = 0; i < (sizeof(buffer) - 1) && *s; i++)
> + *p++ = toupper(*s++);
> +
> + if (*s) {
> + fprintf(stderr, "%s: buffer too small\n", progname);
> exit(3);
> }
>
> - for (p = s2; *p; p++)
> - *p = toupper(*p);
> - return s2;
> + *p = '\0';
> +
> + return buffer;
> }
Hmmm. I recognize this is just build time code so it's not as
critical, but I still don't like the idea of passing back a static
buffer to the caller; it just seems like we are asking for future
trouble. I'm also curious as to why you made this choice in this
revision when the existing code should have worked (passed a const,
returned a non-const). I'm sure I'm missing something obvious, but
can you help me understand why this is necessary?
--
paul-moore.com
