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/openbmc/linux/net/core/
H A Dnet_namespace.cdiff 7866cc57b51c1e118e5d78d1a8f721f378eec5c4 Tue May 30 04:38:12 CDT 2017 Florian Westphal <fw@strlen.de> netns: add and use net_ns_barrier

Quoting Joe Stringer:
If a user loads nf_conntrack_ftp, sends FTP traffic through a network
namespace, destroys that namespace then unloads the FTP helper module,
then the kernel will crash.

Events that lead to the crash:
1. conntrack is created with ftp helper in netns x
2. This netns is destroyed
3. netns destruction is scheduled
4. netns destruction wq starts, removes netns from global list
5. ftp helper is unloaded, which resets all helpers of the conntracks
via for_each_net()

but because netns is already gone from list the for_each_net() loop
doesn't include it, therefore all of these conntracks are unaffected.

6. helper module unload finishes
7. netns wq invokes destructor for rmmod'ed helper

CC: "Eric W. Biederman" <ebiederm@xmission.com>
Reported-by: Joe Stringer <joe@ovn.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
/openbmc/linux/include/net/
H A Dnet_namespace.hdiff 7866cc57b51c1e118e5d78d1a8f721f378eec5c4 Tue May 30 04:38:12 CDT 2017 Florian Westphal <fw@strlen.de> netns: add and use net_ns_barrier

Quoting Joe Stringer:
If a user loads nf_conntrack_ftp, sends FTP traffic through a network
namespace, destroys that namespace then unloads the FTP helper module,
then the kernel will crash.

Events that lead to the crash:
1. conntrack is created with ftp helper in netns x
2. This netns is destroyed
3. netns destruction is scheduled
4. netns destruction wq starts, removes netns from global list
5. ftp helper is unloaded, which resets all helpers of the conntracks
via for_each_net()

but because netns is already gone from list the for_each_net() loop
doesn't include it, therefore all of these conntracks are unaffected.

6. helper module unload finishes
7. netns wq invokes destructor for rmmod'ed helper

CC: "Eric W. Biederman" <ebiederm@xmission.com>
Reported-by: Joe Stringer <joe@ovn.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
/openbmc/linux/net/netfilter/
H A Dnf_conntrack_core.cdiff 7866cc57b51c1e118e5d78d1a8f721f378eec5c4 Tue May 30 04:38:12 CDT 2017 Florian Westphal <fw@strlen.de> netns: add and use net_ns_barrier

Quoting Joe Stringer:
If a user loads nf_conntrack_ftp, sends FTP traffic through a network
namespace, destroys that namespace then unloads the FTP helper module,
then the kernel will crash.

Events that lead to the crash:
1. conntrack is created with ftp helper in netns x
2. This netns is destroyed
3. netns destruction is scheduled
4. netns destruction wq starts, removes netns from global list
5. ftp helper is unloaded, which resets all helpers of the conntracks
via for_each_net()

but because netns is already gone from list the for_each_net() loop
doesn't include it, therefore all of these conntracks are unaffected.

6. helper module unload finishes
7. netns wq invokes destructor for rmmod'ed helper

CC: "Eric W. Biederman" <ebiederm@xmission.com>
Reported-by: Joe Stringer <joe@ovn.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>