From f4eaed28c7834fc049c754f63e6988bbd73778d9 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Wed, 29 Jul 2015 18:40:56 +0200 Subject: [PATCH] act_bpf: fix memory leaks when replacing bpf programs We currently trigger multiple memory leaks when replacing bpf actions, besides others: comm "tc", pid 1909, jiffies 4294851310 (age 1602.796s) hex dump (first 32 bytes): 01 00 00 00 03 00 00 00 00 00 00 00 00 00 00 00 ................ 18 b0 98 6d 00 88 ff ff 00 00 00 00 00 00 00 00 ...m............ backtrace: [] kmemleak_alloc+0x4e/0xb0 [] __vmalloc_node_range+0x1bd/0x2c0 [] __vmalloc+0x4a/0x50 [] bpf_prog_alloc+0x3a/0xa0 [] bpf_prog_create+0x44/0xa0 [] tcf_bpf_init+0x28b/0x3c0 [act_bpf] [] tcf_action_init_1+0x191/0x1b0 [] tcf_action_init+0x82/0xf0 [] tcf_exts_validate+0xb2/0xc0 [] cls_bpf_modify_existing+0x98/0x340 [cls_bpf] [] cls_bpf_change+0x1a6/0x274 [cls_bpf] [] tc_ctl_tfilter+0x335/0x910 [] rtnetlink_rcv_msg+0x95/0x240 [] netlink_rcv_skb+0xaf/0xc0 [] rtnetlink_rcv+0x2e/0x40 [] netlink_unicast+0xef/0x1b0 Issue is that the old content from tcf_bpf is allocated and needs to be released when we replace it. We seem to do that since the beginning of act_bpf on the filter and insns, later on the name as well. Example test case, after patch: # FOO="1,6 0 0 4294967295," # BAR="1,6 0 0 4294967294," # tc actions add action bpf bytecode "$FOO" index 2 # tc actions show action bpf action order 0: bpf bytecode '1,6 0 0 4294967295' default-action pipe index 2 ref 1 bind 0 # tc actions replace action bpf bytecode "$BAR" index 2 # tc actions show action bpf action order 0: bpf bytecode '1,6 0 0 4294967294' default-action pipe index 2 ref 1 bind 0 # tc actions replace action bpf bytecode "$FOO" index 2 # tc actions show action bpf action order 0: bpf bytecode '1,6 0 0 4294967295' default-action pipe index 2 ref 1 bind 0 # tc actions del action bpf index 2 [...] # echo "scan" > /sys/kernel/debug/kmemleak # cat /sys/kernel/debug/kmemleak | grep "comm \"tc\"" | wc -l 0 Fixes: d23b8ad8ab23 ("tc: add BPF based action") Signed-off-by: Daniel Borkmann Signed-off-by: David S. Miller --- net/sched/act_bpf.c | 53 ++++++++++++++++++++++++++++++--------------- 1 file changed, 35 insertions(+), 18 deletions(-) diff --git a/net/sched/act_bpf.c b/net/sched/act_bpf.c index 1df78289e248..d0edeb7a1950 100644 --- a/net/sched/act_bpf.c +++ b/net/sched/act_bpf.c @@ -27,9 +27,10 @@ struct tcf_bpf_cfg { struct bpf_prog *filter; struct sock_filter *bpf_ops; - char *bpf_name; + const char *bpf_name; u32 bpf_fd; u16 bpf_num_ops; + bool is_ebpf; }; static int tcf_bpf(struct sk_buff *skb, const struct tc_action *act, @@ -207,6 +208,7 @@ static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg) cfg->bpf_ops = bpf_ops; cfg->bpf_num_ops = bpf_num_ops; cfg->filter = fp; + cfg->is_ebpf = false; return 0; } @@ -241,18 +243,40 @@ static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg) cfg->bpf_fd = bpf_fd; cfg->bpf_name = name; cfg->filter = fp; + cfg->is_ebpf = true; return 0; } +static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg) +{ + if (cfg->is_ebpf) + bpf_prog_put(cfg->filter); + else + bpf_prog_destroy(cfg->filter); + + kfree(cfg->bpf_ops); + kfree(cfg->bpf_name); +} + +static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog, + struct tcf_bpf_cfg *cfg) +{ + cfg->is_ebpf = tcf_bpf_is_ebpf(prog); + cfg->filter = prog->filter; + + cfg->bpf_ops = prog->bpf_ops; + cfg->bpf_name = prog->bpf_name; +} + static int tcf_bpf_init(struct net *net, struct nlattr *nla, struct nlattr *est, struct tc_action *act, int replace, int bind) { struct nlattr *tb[TCA_ACT_BPF_MAX + 1]; + struct tcf_bpf_cfg cfg, old; struct tc_act_bpf *parm; struct tcf_bpf *prog; - struct tcf_bpf_cfg cfg; bool is_bpf, is_ebpf; int ret; @@ -301,6 +325,9 @@ static int tcf_bpf_init(struct net *net, struct nlattr *nla, prog = to_bpf(act); spin_lock_bh(&prog->tcf_lock); + if (ret != ACT_P_CREATED) + tcf_bpf_prog_fill_cfg(prog, &old); + prog->bpf_ops = cfg.bpf_ops; prog->bpf_name = cfg.bpf_name; @@ -316,32 +343,22 @@ static int tcf_bpf_init(struct net *net, struct nlattr *nla, if (ret == ACT_P_CREATED) tcf_hash_insert(act); + else + tcf_bpf_cfg_cleanup(&old); return ret; destroy_fp: - if (is_ebpf) - bpf_prog_put(cfg.filter); - else - bpf_prog_destroy(cfg.filter); - - kfree(cfg.bpf_ops); - kfree(cfg.bpf_name); - + tcf_bpf_cfg_cleanup(&cfg); return ret; } static void tcf_bpf_cleanup(struct tc_action *act, int bind) { - const struct tcf_bpf *prog = act->priv; - - if (tcf_bpf_is_ebpf(prog)) - bpf_prog_put(prog->filter); - else - bpf_prog_destroy(prog->filter); + struct tcf_bpf_cfg tmp; - kfree(prog->bpf_ops); - kfree(prog->bpf_name); + tcf_bpf_prog_fill_cfg(act->priv, &tmp); + tcf_bpf_cfg_cleanup(&tmp); } static struct tc_action_ops act_bpf_ops __read_mostly = { -- 2.20.1