From: James Carter <jwcart2@gmail.com>
To: Stephen Smalley <stephen.smalley.work@gmail.com>
Cc: "Christian Göttsche" <cgzones@googlemail.com>, selinux@vger.kernel.org
Subject: Re: [RFC PATCH] libsepol: validate permission identifier length
Date: Fri, 8 Dec 2023 12:39:45 -0500 [thread overview]
Message-ID: <CAP+JOzRF-HcrVjihnngqXRbuPYTn2Ra8AU6swP4NXj7S7=n7Hw@mail.gmail.com> (raw)
In-Reply-To: <CAEjxPJ4htnqzDyHFNR_aNJH-hrz_wbM=Z=NN7BjUQDrKBa8e9A@mail.gmail.com>
On Fri, Dec 8, 2023 at 11:06 AM Stephen Smalley
<stephen.smalley.work@gmail.com> wrote:
>
> On Thu, Dec 7, 2023 at 11:53 AM Christian Göttsche
> <cgzones@googlemail.com> wrote:
> >
> > Limit the maximum length of permission identifiers. Otherwise
> > formatting an access vector might fail in the common used helper
> > sepol_av_to_string().
> >
> > The current longest permission within the Reference Policy is
> > x_application_data { paste_after_confirm } with a length of 19.
>
> Android has longer permission names. I'd rather just fix
> sepol_av_to_string() than impose some arbitrary limit here.
>
I agree.
Christian, something like your recent patch to avoid a fixed size
format buffer for xperms would be better.
Thanks for all your work.
Jim
> >
> > Reported-by: oss-fuzz (issue 64832)
> > Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
> > ---
> > The oss-fuzz issue got closed by the latest fuzzer updates (due to
> > unrelated changes that invalid the current reproducer), but the issue is
> > still valid.
> > ---
> > libsepol/src/policydb_validate.c | 20 ++++++++++++++++++++
> > 1 file changed, 20 insertions(+)
> >
> > diff --git a/libsepol/src/policydb_validate.c b/libsepol/src/policydb_validate.c
> > index bd8e9f8f..72681120 100644
> > --- a/libsepol/src/policydb_validate.c
> > +++ b/libsepol/src/policydb_validate.c
> > @@ -366,12 +366,30 @@ bad:
> > return -1;
> > }
> >
> > +static int validate_permission_wrapper(hashtab_key_t k, __attribute__((unused)) hashtab_datum_t d, void *args)
> > +{
> > + sepol_handle_t *handle = args;
> > + const char *name = k;
> > + size_t len = strlen(name);
> > +
> > + if (len == 0 || len >= 32)
> > + goto bad;
> > +
> > + return 0;
> > +
> > +bad:
> > + ERR(handle, "Invalid permission");
> > + return -1;
> > +}
> > +
> > static int validate_common_datum(sepol_handle_t *handle, const common_datum_t *common, validate_t flavors[])
> > {
> > if (validate_value(common->s.value, &flavors[SYM_COMMONS]))
> > goto bad;
> > if (common->permissions.table->nel == 0 || common->permissions.nprim > PERM_SYMTAB_SIZE)
> > goto bad;
> > + if (hashtab_map(common->permissions.table, validate_permission_wrapper, handle))
> > + goto bad;
> >
> > return 0;
> >
> > @@ -395,6 +413,8 @@ static int validate_class_datum(sepol_handle_t *handle, const class_datum_t *cla
> > goto bad;
> > if (class->permissions.nprim > PERM_SYMTAB_SIZE)
> > goto bad;
> > + if (hashtab_map(class->permissions.table, validate_permission_wrapper, handle))
> > + goto bad;
> > if (validate_constraint_nodes(handle, class->permissions.nprim, class->constraints, flavors))
> > goto bad;
> > if (validate_constraint_nodes(handle, 0, class->validatetrans, flavors))
> > --
> > 2.43.0
> >
> >
>
prev parent reply other threads:[~2023-12-08 17:39 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-07 16:53 [RFC PATCH] libsepol: validate permission identifier length Christian Göttsche
2023-12-08 16:05 ` Stephen Smalley
2023-12-08 16:23 ` Stephen Smalley
2023-12-08 17:39 ` James Carter [this message]
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