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broken ping to ipv6 linklocal addresses on debian buster 

I am seeing ping failures to IPv6 linklocal addresses with Debian
buster. Easiest example to reproduce is:

$ ping -c1 -w1 ff02::1%eth1
connect: Invalid argument

$ ping -c1 -w1 ff02::1%eth1
PING ff02::01%eth1(ff02::1%eth1) 56 data bytes
64 bytes from fe80::e0:f9ff:fe0c:37%eth1: icmp_seq=1 ttl=64 time=0.059 ms

git bisect traced the failure to
commit b9ef5513c9 ("smack: Check address length before reading address family")

Arguably ping is being stupid since the buster version is not setting
the address family properly (ping on stretch for example does):

$ strace -e connect ping6 -c1 -w1 ff02::1%eth1
connect(5, {sa_family=AF_UNSPEC,
sa_data="\4\1\0\0\0\0\377\2\0\0\0\0\0\0\0\0\0\0\0\0\0\1\3\0\0\0"}, 28)
= -1 EINVAL (Invalid argument)

but the command works fine on kernels prior to this commit, so this is
breakage which goes against the Linux paradigm of "don't break userspace"

Cc: stable@vger.kernel.org
Reported-by: David Ahern <dsahern@gmail.com>
Suggested-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>

 security/smack/smack_lsm.c | 41 +++++++++++++++++++----------------------
 1 file changed, 19 insertions(+), 22 deletions(-)
This commit is contained in:
Casey Schaufler 2020-02-03 09:15:00 -08:00
parent d5226fa6db
commit 87fbfffcc8
No known key found for this signature in database
GPG Key ID: 38A5157C8C43C811
1 changed files with 19 additions and 22 deletions
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41
security/smack/smack_lsm.c
View File

@ -2831,42 +2831,39 @@ static int smack_socket_connect(struct socket *sock, struct sockaddr *sap,
int addrlen)
{
int rc = 0;
#if IS_ENABLED(CONFIG_IPV6)
struct sockaddr_in6 *sip = (struct sockaddr_in6 *)sap;
#endif
#ifdef SMACK_IPV6_SECMARK_LABELING
struct smack_known *rsp;
struct socket_smack *ssp;
#endif
if (sock->sk == NULL)
return 0;
if (sock->sk->sk_family != PF_INET &&
(!IS_ENABLED(CONFIG_IPV6) || sock->sk->sk_family != PF_INET6))
return 0;
if (addrlen < offsetofend(struct sockaddr, sa_family))
return 0;
if (IS_ENABLED(CONFIG_IPV6) && sap->sa_family == AF_INET6) {
struct sockaddr_in6 *sip = (struct sockaddr_in6 *)sap;
#ifdef SMACK_IPV6_SECMARK_LABELING
ssp = sock->sk->sk_security;
struct smack_known *rsp;
#endif
switch (sock->sk->sk_family) {
case PF_INET:
if (addrlen < sizeof(struct sockaddr_in) ||
sap->sa_family != AF_INET)
return -EINVAL;
rc = smack_netlabel_send(sock->sk, (struct sockaddr_in *)sap);
break;
case PF_INET6:
if (addrlen < SIN6_LEN_RFC2133 || sap->sa_family != AF_INET6)
return -EINVAL;
if (addrlen < SIN6_LEN_RFC2133)
return 0;
#ifdef SMACK_IPV6_SECMARK_LABELING
rsp = smack_ipv6host_label(sip);
if (rsp != NULL)
if (rsp != NULL) {
struct socket_smack *ssp = sock->sk->sk_security;
rc = smk_ipv6_check(ssp->smk_out, rsp, sip,
SMK_CONNECTING);
SMK_CONNECTING);
}
#endif
#ifdef SMACK_IPV6_PORT_LABELING
rc = smk_ipv6_port_check(sock->sk, sip, SMK_CONNECTING);
#endif
break;
return rc;
}
if (sap->sa_family != AF_INET || addrlen < sizeof(struct sockaddr_in))
return 0;
rc = smack_netlabel_send(sock->sk, (struct sockaddr_in *)sap);
return rc;
}