On Mon, Mar 11, 2024 at 5:19 PM James Carter <jwcart2@xxxxxxxxx> wrote:
>
> The function sepol_av_to_string() normally returns a list of
> permissions with a space at the beginning, but it will return '\0'
> if there are no permissions. Unfortunately, functions in
> kernel_to_cil, kernel_to_conf, and module_to_cil assume there is a
> space at the beginning and skip the space by using "perms+1".
>
> In kernel_to_cil, kernel_to_conf, 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>
This patch has been merged.
Jim
> ---
> libsepol/src/kernel_to_cil.c | 11 +++++++++++
> libsepol/src/kernel_to_conf.c | 11 +++++++++++
> libsepol/src/module_to_cil.c | 12 ++++++++++++
> 3 files changed, 34 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/kernel_to_conf.c b/libsepol/src/kernel_to_conf.c
> index 956fb6e8..5860a513 100644
> --- a/libsepol/src/kernel_to_conf.c
> +++ b/libsepol/src/kernel_to_conf.c
> @@ -297,6 +297,12 @@ 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 (strchr(perms, ' ')) {
> perm_prefix = "{ ";
> perm_suffix = " }";
> @@ -1741,6 +1747,11 @@ 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 (*permstring == '\0') {
> + ERR(NULL, "No permisisons in permission string");
> + free(permstring);
> + goto exit;
> + }
> rule = create_str("%s %s %s:%s { %s };",
> flavor, src, tgt, class, permstring+1);
> free(permstring);
> 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
>
