On Thu, May 14, 2015 at 11:39:49PM -0700, Andy Lutomirski wrote: > Per Andrew Morgan's request, add a securebit to allow admins to > disable PR_CAP_AMBIENT_RAISE. This securebit will prevent processes > from adding capabilities to their ambient set. > > For simplicity, this disables PR_CAP_AMBIENT_RAISE entirely rather > than just disabling setting previously cleared bits. > > Requested-by: Andrew G. Morgan <[email protected]> > Cc: Kees Cook <[email protected]> > Cc: Christoph Lameter <[email protected]> > Cc: Serge Hallyn <[email protected]> > Cc: Andy Lutomirski <[email protected]> > Cc: Jonathan Corbet <[email protected]> > Cc: Aaron Jones <[email protected]> > CC: Ted Ts'o <[email protected]> > Cc: [email protected] > Cc: [email protected] > Cc: [email protected] > Cc: [email protected] > Cc: Andrew G. Morgan <[email protected]> > Cc: Mimi Zohar <[email protected]> > Cc: Austin S Hemmelgarn <[email protected]> > Cc: Markku Savela <[email protected]> > Cc: Jarkko Sakkinen <[email protected]> > Cc: Michael Kerrisk <[email protected]> > Signed-off-by: Andy Lutomirski <[email protected]>
Interesting - at first I thought this wouldn't please Andrew as he'd want the inverse, but I guess this way keeps the pure-capabilities mode (with SECURE_ALL_BITS set) ambient-free which I suppose is really the important thing. Acked-by: Serge Hallyn <[email protected]> > --- > include/uapi/linux/securebits.h | 11 ++++++++++- > security/commoncap.c | 3 ++- > 2 files changed, 12 insertions(+), 2 deletions(-) > > diff --git a/include/uapi/linux/securebits.h b/include/uapi/linux/securebits.h > index 985aac9e6bf8..35ac35cef217 100644 > --- a/include/uapi/linux/securebits.h > +++ b/include/uapi/linux/securebits.h > @@ -43,9 +43,18 @@ > #define SECBIT_KEEP_CAPS (issecure_mask(SECURE_KEEP_CAPS)) > #define SECBIT_KEEP_CAPS_LOCKED (issecure_mask(SECURE_KEEP_CAPS_LOCKED)) > > +/* When set, a process cannot add new capabilities to its ambient set. */ > +#define SECURE_NO_CAP_AMBIENT_RAISE 6 > +#define SECURE_NO_CAP_AMBIENT_RAISE_LOCKED 7 /* make bit-6 immutable */ > + > +#define SECBIT_NO_CAP_AMBIENT_RAISE > (issecure_mask(SECURE_NO_CAP_AMBIENT_RAISE)) > +#define SECBIT_NO_CAP_AMBIENT_RAISE_LOCKED \ > + (issecure_mask(SECURE_NO_CAP_AMBIENT_RAISE_LOCKED)) > + > #define SECURE_ALL_BITS (issecure_mask(SECURE_NOROOT) | \ > issecure_mask(SECURE_NO_SETUID_FIXUP) | \ > - issecure_mask(SECURE_KEEP_CAPS)) > + issecure_mask(SECURE_KEEP_CAPS) | \ > + issecure_mask(SECURE_NO_CAP_AMBIENT_RAISE)) > #define SECURE_ALL_LOCKS (SECURE_ALL_BITS << 1) > > #endif /* _UAPI_LINUX_SECUREBITS_H */ > diff --git a/security/commoncap.c b/security/commoncap.c > index 09541a6a85a0..98aa1b129c12 100644 > --- a/security/commoncap.c > +++ b/security/commoncap.c > @@ -983,7 +983,8 @@ int cap_task_prctl(int option, unsigned long arg2, > unsigned long arg3, > if (arg2 == PR_CAP_AMBIENT_RAISE && > (!cap_raised(current_cred()->cap_permitted, arg3) || > !cap_raised(current_cred()->cap_inheritable, > - arg3))) > + arg3) || > + issecure(SECURE_NO_CAP_AMBIENT_RAISE))) > return -EPERM; > > new = prepare_creds(); > -- > 2.1.0 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
