Hi Christian,
First of all, there's a typo in the subject: umber -> number ;)
On 2023/07/06 21:23, Christian Göttsche wrote:
> Security classes have only up to 32 permissions, hence using an u16 is
> sufficient (while improving padding).
>
> Also use a fixed sized cast in a bit shift to work correctly on
> architectures where sizeof(unsigned int) != sizeof(u32).
>
> Signed-off-by: Christian Göttsche <cgzones@xxxxxxxxxxxxxx>
> ---
> security/selinux/ss/services.c | 6 +++---
> security/selinux/ss/services.h | 2 +-
> 2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
> index 78946b71c1c1..3275cfe2c8f7 100644
> --- a/security/selinux/ss/services.c
> +++ b/security/selinux/ss/services.c
> @@ -97,7 +97,6 @@ static int selinux_set_mapping(struct policydb *pol,
> struct selinux_map *out_map)
> {
> u16 i, j;
> - unsigned k;
> bool print_unknown_handle = false;
>
> /* Find number of classes in the input mapping */
> @@ -117,6 +116,7 @@ static int selinux_set_mapping(struct policydb *pol,
> while (map[j].name) {
> const struct security_class_mapping *p_in = map + (j++);
> struct selinux_mapping *p_out = out_map->mapping + j;
> + u16 k;
>
> /* An empty class string skips ahead */
> if (!strcmp(p_in->name, "")) {
> @@ -202,7 +202,7 @@ static void map_decision(struct selinux_map *map,
> {
> if (tclass < map->size) {
> struct selinux_mapping *mapping = &map->mapping[tclass];
> - unsigned int i, n = mapping->num_perms;
> + u16 i, n = mapping->num_perms;
> u32 result;
>
> for (i = 0, result = 0; i < n; i++) {
> @@ -230,7 +230,7 @@ static void map_decision(struct selinux_map *map,
> * should audit that denial
> */
> for (; i < (sizeof(u32)*8); i++)
> - result |= 1<<i;
> + result |= 1<<((u32)i);
Is it really necessary to do explicit conversion here? Its value is
known to be small, and IIUC, u16 will be implicitly promoted to int as
an operand of <<, as described here:
https://en.cppreference.com/w/c/language/conversion#Integer_promotions
> avd->auditdeny = result;
> }
> }
> diff --git a/security/selinux/ss/services.h b/security/selinux/ss/services.h
> index 8a9b85f44b66..b6f99353301e 100644
> --- a/security/selinux/ss/services.h
> +++ b/security/selinux/ss/services.h
> @@ -12,7 +12,7 @@
> /* Mapping for a single class */
> struct selinux_mapping {
> u16 value; /* policy value for class */
> - unsigned int num_perms; /* number of permissions in class */
> + u16 num_perms; /* number of permissions in class */
> u32 perms[sizeof(u32) * 8]; /* policy values for permissions */
> };
>
