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| author | Martin KaFai Lau <kafai@fb.com> | 2017-06-05 12:15:46 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-06-06 15:41:22 -0400 |
| commit | dc4bb0e2356149aee4cdae061936f3bbdd45595c (patch) | |
| tree | 519cc48437a65eade73ab7cb150e32076cbbc17e /kernel/bpf | |
| parent | 8ea4fae926afd81f4d7fd43444562afc8629f77c (diff) | |
| download | linux-dc4bb0e2356149aee4cdae061936f3bbdd45595c.tar.bz2 | |
bpf: Introduce bpf_prog ID
This patch generates an unique ID for each BPF_PROG_LOAD-ed prog.
It is worth to note that each BPF_PROG_LOAD-ed prog will have
a different ID even they have the same bpf instructions.
The ID is generated by the existing idr_alloc_cyclic().
The ID is ranged from [1, INT_MAX). It is allocated in cyclic manner,
so an ID will get reused every 2 billion BPF_PROG_LOAD.
The bpf_prog_alloc_id() is done after bpf_prog_select_runtime()
because the jit process may have allocated a new prog. Hence,
we need to ensure the value of pointer 'prog' will not be changed
any more before storing the prog to the prog_idr.
After bpf_prog_select_runtime(), the prog is read-only. Hence,
the id is stored in 'struct bpf_prog_aux'.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/syscall.c | 40 |
1 files changed, 39 insertions, 1 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 59da103adb85..2a1b32b470f1 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -22,8 +22,11 @@ #include <linux/filter.h> #include <linux/version.h> #include <linux/kernel.h> +#include <linux/idr.h> DEFINE_PER_CPU(int, bpf_prog_active); +static DEFINE_IDR(prog_idr); +static DEFINE_SPINLOCK(prog_idr_lock); int sysctl_unprivileged_bpf_disabled __read_mostly; @@ -650,6 +653,34 @@ static void bpf_prog_uncharge_memlock(struct bpf_prog *prog) free_uid(user); } +static int bpf_prog_alloc_id(struct bpf_prog *prog) +{ + int id; + + spin_lock_bh(&prog_idr_lock); + id = idr_alloc_cyclic(&prog_idr, prog, 1, INT_MAX, GFP_ATOMIC); + if (id > 0) + prog->aux->id = id; + spin_unlock_bh(&prog_idr_lock); + + /* id is in [1, INT_MAX) */ + if (WARN_ON_ONCE(!id)) + return -ENOSPC; + + return id > 0 ? 0 : id; +} + +static void bpf_prog_free_id(struct bpf_prog *prog) +{ + /* cBPF to eBPF migrations are currently not in the idr store. */ + if (!prog->aux->id) + return; + + spin_lock_bh(&prog_idr_lock); + idr_remove(&prog_idr, prog->aux->id); + spin_unlock_bh(&prog_idr_lock); +} + static void __bpf_prog_put_rcu(struct rcu_head *rcu) { struct bpf_prog_aux *aux = container_of(rcu, struct bpf_prog_aux, rcu); @@ -663,6 +694,7 @@ void bpf_prog_put(struct bpf_prog *prog) { if (atomic_dec_and_test(&prog->aux->refcnt)) { trace_bpf_prog_put_rcu(prog); + bpf_prog_free_id(prog); bpf_prog_kallsyms_del(prog); call_rcu(&prog->aux->rcu, __bpf_prog_put_rcu); } @@ -857,15 +889,21 @@ static int bpf_prog_load(union bpf_attr *attr) if (err < 0) goto free_used_maps; + err = bpf_prog_alloc_id(prog); + if (err) + goto free_used_maps; + err = bpf_prog_new_fd(prog); if (err < 0) /* failed to allocate fd */ - goto free_used_maps; + goto free_id; bpf_prog_kallsyms_add(prog); trace_bpf_prog_load(prog, err); return err; +free_id: + bpf_prog_free_id(prog); free_used_maps: free_used_maps(prog->aux); free_prog: |