On Mon, 11 Mar 2024 at 13:48, James Carter <jwcart2@xxxxxxxxx> wrote:
>
> The function sepol_av_to_string() returns a list of permissions
> with a space at the beginning. This fits the normal formating of
> permisisons for a policy.conf policy which uses a format of
> "{ p1 p2 ... pn }", but not the formating for a CIL policy which uses
> a format of "(p1 p2 ... pn)". Both kernel_to_cil and module_to_cil
> skip the space by using "perms+1", but this is a problem if there
> are no permissions because sepol_av_to_string() returns '\0'.
>
> In kernel_to_cil and module_to_cil, check for the permission string
> being '\0' and return an error if it is.
>
> Reported-by: oss-fuzz (issue 67276)
> Signed-off-by: James Carter <jwcart2@xxxxxxxxx>
> ---
> libsepol/src/kernel_to_cil.c | 11 +++++++++++
> libsepol/src/module_to_cil.c | 12 ++++++++++++
I think there are also two occurrences in libsepol/src/kernel_to_conf.c.
Also: s/permisisons/permissions/
> 2 files changed, 23 insertions(+)
>
> diff --git a/libsepol/src/kernel_to_cil.c b/libsepol/src/kernel_to_cil.c
> index a081915e..e20ba4af 100644
> --- a/libsepol/src/kernel_to_cil.c
> +++ b/libsepol/src/kernel_to_cil.c
> @@ -302,6 +302,12 @@ static int class_constraint_rules_to_strs(struct policydb *pdb, char *classkey,
> rc = -1;
> goto exit;
> }
> + if (*perms == '\0') {
> + ERR(NULL, "No permisisons in permission string");
> + free(perms);
> + rc = -1;
> + goto exit;
> + }
>
> if (is_mls) {
> key_word = "mlsconstrain";
> @@ -1775,6 +1781,11 @@ static char *avtab_node_to_str(struct policydb *pdb, avtab_key_t *key, avtab_dat
> ERR(NULL, "Failed to generate permission string");
> goto exit;
> }
> + if (*perms == '\0') {
> + ERR(NULL, "No permisisons in permission string");
> + free(perms);
> + goto exit;
> + }
> rule = create_str("(%s %s %s (%s (%s)))",
> flavor, src, tgt, class, perms+1);
> free(perms);
> diff --git a/libsepol/src/module_to_cil.c b/libsepol/src/module_to_cil.c
> index 6699a46b..3b3480bf 100644
> --- a/libsepol/src/module_to_cil.c
> +++ b/libsepol/src/module_to_cil.c
> @@ -593,6 +593,12 @@ static int avrule_to_cil(int indent, struct policydb *pdb, uint32_t type, const
> rc = -1;
> goto exit;
> }
> + if (*perms == '\0') {
> + ERR(NULL, "No permissions in permission string");
> + free(perms);
> + rc = -1;
> + goto exit;
> + }
> cil_println(indent, "(%s %s %s (%s (%s)))",
> rule, src, tgt,
> pdb->p_class_val_to_name[classperm->tclass - 1],
> @@ -1973,6 +1979,12 @@ static int constraints_to_cil(int indent, struct policydb *pdb, char *classkey,
> rc = -1;
> goto exit;
> }
> + if (*perms == '\0') {
> + ERR(NULL, "No permissions in permission string");
> + free(perms);
> + rc = -1;
> + goto exit;
> + }
> cil_println(indent, "(%sconstrain (%s (%s)) %s)", mls, classkey, perms + 1, expr);
> free(perms);
> } else {
> --
> 2.44.0
>
>
