| Message ID | 1314990654-32252-1-git-send-email-zenczykowski@gmail.com |
|---|---|
| State | Superseded, archived |
| Delegated to: | David Miller |
| Headers | show |
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On Fri, 2011-09-02 at 12:10 -0700, Maciej Żenczykowski wrote: > From: Maciej Żenczykowski <maze@google.com> > > Up till now the IP{,V6}_TRANSPARENT socket options (which actually set > the same bit in the socket struct) have required CAP_NET_ADMIN > privileges to set or clear the option. > > - we make clearing the bit not require any privileges. > - we deprecate using CAP_NET_ADMIN for this purpose. > - we introduce a new capability CAP_NET_TRANSPARENT, > which is tailored to allow setting just this bit. > - we allow either one of CAP_NET_TRANSPARENT or CAP_NET_RAW > to set this bit, because raw sockets already effectively > allow you to emulate socket transparency, and make the > transition easier for apps not desiring to use a brand > new capability (because of header file or glibc support) > - we print a warning (but allow it) if you try to set > the socket option with CAP_NET_ADMIN privs, but without > either one of CAP_NET_TRANSPARENT or CAP_NET_RAW. > > The reason for introducing a new capability is that while > transparent sockets are potentially dangerous (and can let you > spoof your source IP on traffic), they don't normally give you > the full 'freedom' of eavesdropping and/or spoofing that raw sockets > give you. > > Signed-off-by: Maciej Żenczykowski <maze@google.com> > CC: Balazs Scheidler <bazsi@balabit.hu> This is ok for me, as long as the security maintainers allow the introduction of this new cap. Thanks for doing this and sorry for the late reply. Acked-by: Balazs Scheidler <bazsi@balabit.hu>
>> From: Maciej Żenczykowski <maze@google.com> >> >> Up till now the IP{,V6}_TRANSPARENT socket options (which actually set >> the same bit in the socket struct) have required CAP_NET_ADMIN >> privileges to set or clear the option. >> >> - we make clearing the bit not require any privileges. >> - we deprecate using CAP_NET_ADMIN for this purpose. >> - we introduce a new capability CAP_NET_TRANSPARENT, >> which is tailored to allow setting just this bit. >> - we allow either one of CAP_NET_TRANSPARENT or CAP_NET_RAW >> to set this bit, because raw sockets already effectively >> allow you to emulate socket transparency, and make the >> transition easier for apps not desiring to use a brand >> new capability (because of header file or glibc support) >> - we print a warning (but allow it) if you try to set >> the socket option with CAP_NET_ADMIN privs, but without >> either one of CAP_NET_TRANSPARENT or CAP_NET_RAW. >> >> The reason for introducing a new capability is that while >> transparent sockets are potentially dangerous (and can let you >> spoof your source IP on traffic), they don't normally give you >> the full 'freedom' of eavesdropping and/or spoofing that raw sockets >> give you. >> >> Signed-off-by: Maciej Żenczykowski <maze@google.com> >> CC: Balazs Scheidler <bazsi@balabit.hu> > > This is ok for me, as long as the security maintainers allow the > introduction of this new cap. > > Thanks for doing this and sorry for the late reply. > > Acked-by: Balazs Scheidler <bazsi@balabit.hu> > > -- > Bazsi I'm not really sure who else to CC on this... -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Balazs Scheidler <bazsi@balabit.hu> Date: Tue, 13 Sep 2011 17:27:09 +0200 > On Fri, 2011-09-02 at 12:10 -0700, Maciej Żenczykowski wrote: >> From: Maciej Żenczykowski <maze@google.com> >> >> Up till now the IP{,V6}_TRANSPARENT socket options (which actually set >> the same bit in the socket struct) have required CAP_NET_ADMIN >> privileges to set or clear the option. >> >> - we make clearing the bit not require any privileges. >> - we deprecate using CAP_NET_ADMIN for this purpose. >> - we introduce a new capability CAP_NET_TRANSPARENT, >> which is tailored to allow setting just this bit. >> - we allow either one of CAP_NET_TRANSPARENT or CAP_NET_RAW >> to set this bit, because raw sockets already effectively >> allow you to emulate socket transparency, and make the >> transition easier for apps not desiring to use a brand >> new capability (because of header file or glibc support) >> - we print a warning (but allow it) if you try to set >> the socket option with CAP_NET_ADMIN privs, but without >> either one of CAP_NET_TRANSPARENT or CAP_NET_RAW. >> >> The reason for introducing a new capability is that while >> transparent sockets are potentially dangerous (and can let you >> spoof your source IP on traffic), they don't normally give you >> the full 'freedom' of eavesdropping and/or spoofing that raw sockets >> give you. >> >> Signed-off-by: Maciej Żenczykowski <maze@google.com> >> CC: Balazs Scheidler <bazsi@balabit.hu> > > This is ok for me, as long as the security maintainers allow the > introduction of this new cap. > > Thanks for doing this and sorry for the late reply. > > Acked-by: Balazs Scheidler <bazsi@balabit.hu> I'm fine with this change too and I'll apply it as soon as at least one security person ACK's the addition of the new capability bit. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/linux/capability.h b/include/linux/capability.h index c421123..a115ed4 100644 --- a/include/linux/capability.h +++ b/include/linux/capability.h @@ -198,7 +198,7 @@ struct cpu_vfs_cap_data { /* Allow modification of routing tables */ /* Allow setting arbitrary process / process group ownership on sockets */ -/* Allow binding to any address for transparent proxying */ +/* Allow binding to any address for transparent proxying (deprecated) */ /* Allow setting TOS (type of service) */ /* Allow setting promiscuous mode */ /* Allow clearing driver statistics */ @@ -210,6 +210,7 @@ struct cpu_vfs_cap_data { /* Allow use of RAW sockets */ /* Allow use of PACKET sockets */ +/* Allow binding to any address for transparent proxying */ #define CAP_NET_RAW 13 @@ -332,7 +333,7 @@ struct cpu_vfs_cap_data { #define CAP_AUDIT_CONTROL 30 -#define CAP_SETFCAP 31 +#define CAP_SETFCAP 31 /* Override MAC access. The base kernel enforces no MAC policy. @@ -357,10 +358,14 @@ struct cpu_vfs_cap_data { /* Allow triggering something that will wake the system */ -#define CAP_WAKE_ALARM 35 +#define CAP_WAKE_ALARM 35 + +/* Allow binding to any address for transparent proxying */ + +#define CAP_NET_TRANSPARENT 36 -#define CAP_LAST_CAP CAP_WAKE_ALARM +#define CAP_LAST_CAP CAP_NET_TRANSPARENT #define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP) diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index 8905e92..44efa39 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -961,12 +961,30 @@ mc_msf_out: break; case IP_TRANSPARENT: - if (!capable(CAP_NET_ADMIN)) { - err = -EPERM; - break; - } if (optlen < 1) goto e_inval; + /* Always allow clearing the transparent proxy socket option. + * The pre-3.2 permission for setting this was CAP_NET_ADMIN, + * and this is still supported - but deprecated. As of Linux + * 3.2 the proper permission is one of CAP_NET_TRANSPARENT + * (preferred, a new capability) or CAP_NET_RAW. The latter + * is supported to make the transition easier (and because + * raw sockets already effectively allow one to emulate + * socket transparency). + */ + if (!!val && !capable(CAP_NET_TRANSPARENT) + && !capable(CAP_NET_RAW)) { + if (!capable(CAP_NET_ADMIN)) { + err = -EPERM; + break; + } + printk_once(KERN_WARNING "%s (%d): " + "deprecated: attempt to set socket option " + "IP_TRANSPARENT with CAP_NET_ADMIN but " + "without either one of CAP_NET_TRANSPARENT " + "or CAP_NET_RAW.\n", + current->comm, task_pid_nr(current)); + } inet->transparent = !!val; break; diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c index 147ede38..c840098 100644 --- a/net/ipv6/ipv6_sockglue.c +++ b/net/ipv6/ipv6_sockglue.c @@ -343,13 +343,32 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname, break; case IPV6_TRANSPARENT: - if (!capable(CAP_NET_ADMIN)) { - retv = -EPERM; - break; - } if (optlen < sizeof(int)) goto e_inval; - /* we don't have a separate transparent bit for IPV6 we use the one in the IPv4 socket */ + /* Always allow clearing the transparent proxy socket option. + * The pre-3.2 permission for setting this was CAP_NET_ADMIN, + * and this is still supported - but deprecated. As of Linux + * 3.2 the proper permission is one of CAP_NET_TRANSPARENT + * (preferred, a new capability) or CAP_NET_RAW. The latter + * is supported to make the transition easier (and because + * raw sockets already effectively allow one to emulate + * socket transparency). + */ + if (valbool && !capable(CAP_NET_TRANSPARENT) + && !capable(CAP_NET_RAW)) { + if (!capable(CAP_NET_ADMIN)) { + retv = -EPERM; + break; + } + printk_once(KERN_WARNING "%s (%d): " + "deprecated: attempt to set socket option " + "IPV6_TRANSPARENT with CAP_NET_ADMIN but " + "without either one of CAP_NET_TRANSPARENT " + "or CAP_NET_RAW.\n", + current->comm, task_pid_nr(current)); + } + /* we don't have a separate transparent bit for IPV6 we use the + * one in the IPv4 socket */ inet_sk(sk)->transparent = valbool; retv = 0; break;