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bpf: allocate cgroup storage entries on attaching bpf programs

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If a bpf program is using cgroup local storage, allocate
a bpf_cgroup_storage structure automatically on attaching the program
to a cgroup and save the pointer into the corresponding bpf_prog_list
entry.
Analogically, release the cgroup local storage on detaching
of the bpf program.

Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Roman Gushchin 2018-08-02 14:27:20 -07:00 committed by Daniel Borkmann
parent aa0ad5b039
commit d7bf2c10af
2 changed files with 32 additions and 4 deletions
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1
include/linux/bpf-cgroup.h
View File

@ -43,6 +43,7 @@ struct bpf_cgroup_storage {
struct bpf_prog_list { struct bpf_prog_list {
struct list_head node; struct list_head node;
struct bpf_prog *prog; struct bpf_prog *prog;
struct bpf_cgroup_storage *storage;
}; };
struct bpf_prog_array; struct bpf_prog_array;

35
kernel/bpf/cgroup.c
View File

@ -34,6 +34,8 @@ void cgroup_bpf_put(struct cgroup *cgrp)
list_for_each_entry_safe(pl, tmp, progs, node) { list_for_each_entry_safe(pl, tmp, progs, node) {
list_del(&pl->node); list_del(&pl->node);
bpf_prog_put(pl->prog); bpf_prog_put(pl->prog);
bpf_cgroup_storage_unlink(pl->storage);
bpf_cgroup_storage_free(pl->storage);
kfree(pl); kfree(pl);
static_branch_dec(&cgroup_bpf_enabled_key); static_branch_dec(&cgroup_bpf_enabled_key);
} }
@ -188,6 +190,7 @@ int __cgroup_bpf_attach(struct cgroup *cgrp, struct bpf_prog *prog,
{ {
struct list_head *progs = &cgrp->bpf.progs[type]; struct list_head *progs = &cgrp->bpf.progs[type];
struct bpf_prog *old_prog = NULL; struct bpf_prog *old_prog = NULL;
struct bpf_cgroup_storage *storage, *old_storage = NULL;
struct cgroup_subsys_state *css; struct cgroup_subsys_state *css;
struct bpf_prog_list *pl; struct bpf_prog_list *pl;
bool pl_was_allocated; bool pl_was_allocated;
@ -210,31 +213,47 @@ int __cgroup_bpf_attach(struct cgroup *cgrp, struct bpf_prog *prog,
if (prog_list_length(progs) >= BPF_CGROUP_MAX_PROGS) if (prog_list_length(progs) >= BPF_CGROUP_MAX_PROGS)
return -E2BIG; return -E2BIG;
storage = bpf_cgroup_storage_alloc(prog);
if (IS_ERR(storage))
return -ENOMEM;
if (flags & BPF_F_ALLOW_MULTI) { if (flags & BPF_F_ALLOW_MULTI) {
list_for_each_entry(pl, progs, node) list_for_each_entry(pl, progs, node) {
if (pl->prog == prog) if (pl->prog == prog) {
/* disallow attaching the same prog twice */ /* disallow attaching the same prog twice */
bpf_cgroup_storage_free(storage);
return -EINVAL; return -EINVAL;
}
}
pl = kmalloc(sizeof(*pl), GFP_KERNEL); pl = kmalloc(sizeof(*pl), GFP_KERNEL);
if (!pl) if (!pl) {
bpf_cgroup_storage_free(storage);
return -ENOMEM; return -ENOMEM;
}
pl_was_allocated = true; pl_was_allocated = true;
pl->prog = prog; pl->prog = prog;
pl->storage = storage;
list_add_tail(&pl->node, progs); list_add_tail(&pl->node, progs);
} else { } else {
if (list_empty(progs)) { if (list_empty(progs)) {
pl = kmalloc(sizeof(*pl), GFP_KERNEL); pl = kmalloc(sizeof(*pl), GFP_KERNEL);
if (!pl) if (!pl) {
bpf_cgroup_storage_free(storage);
return -ENOMEM; return -ENOMEM;
}
pl_was_allocated = true; pl_was_allocated = true;
list_add_tail(&pl->node, progs); list_add_tail(&pl->node, progs);
} else { } else {
pl = list_first_entry(progs, typeof(*pl), node); pl = list_first_entry(progs, typeof(*pl), node);
old_prog = pl->prog; old_prog = pl->prog;
old_storage = pl->storage;
bpf_cgroup_storage_unlink(old_storage);
pl_was_allocated = false; pl_was_allocated = false;
} }
pl->prog = prog; pl->prog = prog;
pl->storage = storage;
} }
cgrp->bpf.flags[type] = flags; cgrp->bpf.flags[type] = flags;
@ -257,10 +276,13 @@ int __cgroup_bpf_attach(struct cgroup *cgrp, struct bpf_prog *prog,
} }
static_branch_inc(&cgroup_bpf_enabled_key); static_branch_inc(&cgroup_bpf_enabled_key);
if (old_storage)
bpf_cgroup_storage_free(old_storage);
if (old_prog) { if (old_prog) {
bpf_prog_put(old_prog); bpf_prog_put(old_prog);
static_branch_dec(&cgroup_bpf_enabled_key); static_branch_dec(&cgroup_bpf_enabled_key);
} }
bpf_cgroup_storage_link(storage, cgrp, type);
return 0; return 0;
cleanup: cleanup:
@ -276,6 +298,9 @@ cleanup:
/* and cleanup the prog list */ /* and cleanup the prog list */
pl->prog = old_prog; pl->prog = old_prog;
bpf_cgroup_storage_free(pl->storage);
pl->storage = old_storage;
bpf_cgroup_storage_link(old_storage, cgrp, type);
if (pl_was_allocated) { if (pl_was_allocated) {
list_del(&pl->node); list_del(&pl->node);
kfree(pl); kfree(pl);
@ -356,6 +381,8 @@ int __cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
/* now can actually delete it from this cgroup list */ /* now can actually delete it from this cgroup list */
list_del(&pl->node); list_del(&pl->node);
bpf_cgroup_storage_unlink(pl->storage);
bpf_cgroup_storage_free(pl->storage);
kfree(pl); kfree(pl);
if (list_empty(progs)) if (list_empty(progs))
/* last program was detached, reset flags to zero */ /* last program was detached, reset flags to zero */