4.19-stable review patch. If anyone has any objections, please let me know.
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From: Florian Westphal fw@strlen.de
commit f342de4e2f33e0e39165d8639387aa6c19dff660 upstream.
This reverts commit e0abdadcc6e1.
core.c:nf_hook_slow assumes that the upper 16 bits of NF_DROP verdicts contain a valid errno, i.e. -EPERM, -EHOSTUNREACH or similar, or 0.
Due to the reverted commit, its possible to provide a positive value, e.g. NF_ACCEPT (1), which results in use-after-free.
Its not clear to me why this commit was made.
NF_QUEUE is not used by nftables; "queue" rules in nftables will result in use of "nft_queue" expression.
If we later need to allow specifiying errno values from userspace (do not know why), this has to call NF_DROP_GETERR and check that "err <= 0" holds true.
Fixes: e0abdadcc6e1 ("netfilter: nf_tables: accept QUEUE/DROP verdict parameters") Cc: stable@vger.kernel.org Reported-by: Notselwyn notselwyn@pwning.tech Signed-off-by: Florian Westphal fw@strlen.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/netfilter/nf_tables_api.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-)
--- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -7341,16 +7341,10 @@ static int nft_verdict_init(const struct data->verdict.code = ntohl(nla_get_be32(tb[NFTA_VERDICT_CODE]));
switch (data->verdict.code) { - default: - switch (data->verdict.code & NF_VERDICT_MASK) { - case NF_ACCEPT: - case NF_DROP: - case NF_QUEUE: - break; - default: - return -EINVAL; - } - /* fall through */ + case NF_ACCEPT: + case NF_DROP: + case NF_QUEUE: + break; case NFT_CONTINUE: case NFT_BREAK: case NFT_RETURN: @@ -7370,6 +7364,8 @@ static int nft_verdict_init(const struct
data->verdict.chain = chain; break; + default: + return -EINVAL; }
desc->len = sizeof(data->verdict);