diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h index 92bc89ae7e20..c970a25d2a49 100644 --- a/include/linux/bpf-cgroup.h +++ b/include/linux/bpf-cgroup.h @@ -21,20 +21,19 @@ struct cgroup_bpf { */ struct bpf_prog *prog[MAX_BPF_ATTACH_TYPE]; struct bpf_prog __rcu *effective[MAX_BPF_ATTACH_TYPE]; + bool disallow_override[MAX_BPF_ATTACH_TYPE]; }; void cgroup_bpf_put(struct cgroup *cgrp); void cgroup_bpf_inherit(struct cgroup *cgrp, struct cgroup *parent); -void __cgroup_bpf_update(struct cgroup *cgrp, - struct cgroup *parent, - struct bpf_prog *prog, - enum bpf_attach_type type); +int __cgroup_bpf_update(struct cgroup *cgrp, struct cgroup *parent, + struct bpf_prog *prog, enum bpf_attach_type type, + bool overridable); /* Wrapper for __cgroup_bpf_update() protected by cgroup_mutex */ -void cgroup_bpf_update(struct cgroup *cgrp, - struct bpf_prog *prog, - enum bpf_attach_type type); +int cgroup_bpf_update(struct cgroup *cgrp, struct bpf_prog *prog, + enum bpf_attach_type type, bool overridable); int __cgroup_bpf_run_filter_skb(struct sock *sk, struct sk_buff *skb, diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 0eb0e87dbe9f..d2b0ac799d03 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -116,6 +116,12 @@ enum bpf_attach_type { #define MAX_BPF_ATTACH_TYPE __MAX_BPF_ATTACH_TYPE +/* If BPF_F_ALLOW_OVERRIDE flag is used in BPF_PROG_ATTACH command + * to the given target_fd cgroup the descendent cgroup will be able to + * override effective bpf program that was inherited from this cgroup + */ +#define BPF_F_ALLOW_OVERRIDE (1U << 0) + #define BPF_PSEUDO_MAP_FD 1 /* flags for BPF_MAP_UPDATE_ELEM command */ @@ -171,6 +177,7 @@ union bpf_attr { __u32 target_fd; /* container object to attach to */ __u32 attach_bpf_fd; /* eBPF program to attach */ __u32 attach_type; + __u32 attach_flags; }; } __attribute__((aligned(8))); diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c index a515f7b007c6..da0f53690295 100644 --- a/kernel/bpf/cgroup.c +++ b/kernel/bpf/cgroup.c @@ -52,6 +52,7 @@ void cgroup_bpf_inherit(struct cgroup *cgrp, struct cgroup *parent) e = rcu_dereference_protected(parent->bpf.effective[type], lockdep_is_held(&cgroup_mutex)); rcu_assign_pointer(cgrp->bpf.effective[type], e); + cgrp->bpf.disallow_override[type] = parent->bpf.disallow_override[type]; } } @@ -82,30 +83,63 @@ void cgroup_bpf_inherit(struct cgroup *cgrp, struct cgroup *parent) * * Must be called with cgroup_mutex held. */ -void __cgroup_bpf_update(struct cgroup *cgrp, - struct cgroup *parent, - struct bpf_prog *prog, - enum bpf_attach_type type) +int __cgroup_bpf_update(struct cgroup *cgrp, struct cgroup *parent, + struct bpf_prog *prog, enum bpf_attach_type type, + bool new_overridable) { - struct bpf_prog *old_prog, *effective; + struct bpf_prog *old_prog, *effective = NULL; struct cgroup_subsys_state *pos; + bool overridable = true; - old_prog = xchg(cgrp->bpf.prog + type, prog); + if (parent) { + overridable = !parent->bpf.disallow_override[type]; + effective = rcu_dereference_protected(parent->bpf.effective[type], + lockdep_is_held(&cgroup_mutex)); + } - effective = (!prog && parent) ? - rcu_dereference_protected(parent->bpf.effective[type], - lockdep_is_held(&cgroup_mutex)) : - prog; + if (prog && effective && !overridable) + /* if parent has non-overridable prog attached, disallow + * attaching new programs to descendent cgroup + */ + return -EPERM; + + if (prog && effective && overridable != new_overridable) + /* if parent has overridable prog attached, only + * allow overridable programs in descendent cgroup + */ + return -EPERM; + + old_prog = cgrp->bpf.prog[type]; + + if (prog) { + overridable = new_overridable; + effective = prog; + if (old_prog && + cgrp->bpf.disallow_override[type] == new_overridable) + /* disallow attaching non-overridable on top + * of existing overridable in this cgroup + * and vice versa + */ + return -EPERM; + } + + if (!prog && !old_prog) + /* report error when trying to detach and nothing is attached */ + return -ENOENT; + + cgrp->bpf.prog[type] = prog; css_for_each_descendant_pre(pos, &cgrp->self) { struct cgroup *desc = container_of(pos, struct cgroup, self); /* skip the subtree if the descendant has its own program */ - if (desc->bpf.prog[type] && desc != cgrp) + if (desc->bpf.prog[type] && desc != cgrp) { pos = css_rightmost_descendant(pos); - else + } else { rcu_assign_pointer(desc->bpf.effective[type], effective); + desc->bpf.disallow_override[type] = !overridable; + } } if (prog) @@ -115,6 +149,7 @@ void __cgroup_bpf_update(struct cgroup *cgrp, bpf_prog_put(old_prog); static_branch_dec(&cgroup_bpf_enabled_key); } + return 0; } /** diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 19b6129eab23..bbb016adbaeb 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -920,13 +920,14 @@ static int bpf_obj_get(const union bpf_attr *attr) #ifdef CONFIG_CGROUP_BPF -#define BPF_PROG_ATTACH_LAST_FIELD attach_type +#define BPF_PROG_ATTACH_LAST_FIELD attach_flags static int bpf_prog_attach(const union bpf_attr *attr) { + enum bpf_prog_type ptype; struct bpf_prog *prog; struct cgroup *cgrp; - enum bpf_prog_type ptype; + int ret; if (!capable(CAP_NET_ADMIN)) return -EPERM; @@ -934,6 +935,9 @@ static int bpf_prog_attach(const union bpf_attr *attr) if (CHECK_ATTR(BPF_PROG_ATTACH)) return -EINVAL; + if (attr->attach_flags & ~BPF_F_ALLOW_OVERRIDE) + return -EINVAL; + switch (attr->attach_type) { case BPF_CGROUP_INET_INGRESS: case BPF_CGROUP_INET_EGRESS: @@ -956,10 +960,13 @@ static int bpf_prog_attach(const union bpf_attr *attr) return PTR_ERR(cgrp); } - cgroup_bpf_update(cgrp, prog, attr->attach_type); + ret = cgroup_bpf_update(cgrp, prog, attr->attach_type, + attr->attach_flags & BPF_F_ALLOW_OVERRIDE); + if (ret) + bpf_prog_put(prog); cgroup_put(cgrp); - return 0; + return ret; } #define BPF_PROG_DETACH_LAST_FIELD attach_type @@ -967,6 +974,7 @@ static int bpf_prog_attach(const union bpf_attr *attr) static int bpf_prog_detach(const union bpf_attr *attr) { struct cgroup *cgrp; + int ret; if (!capable(CAP_NET_ADMIN)) return -EPERM; @@ -982,7 +990,7 @@ static int bpf_prog_detach(const union bpf_attr *attr) if (IS_ERR(cgrp)) return PTR_ERR(cgrp); - cgroup_bpf_update(cgrp, NULL, attr->attach_type); + ret = cgroup_bpf_update(cgrp, NULL, attr->attach_type, false); cgroup_put(cgrp); break; @@ -990,7 +998,7 @@ static int bpf_prog_detach(const union bpf_attr *attr) return -EINVAL; } - return 0; + return ret; } #endif /* CONFIG_CGROUP_BPF */ diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 688dd02af985..53bbca7c4859 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -6498,15 +6498,16 @@ static __init int cgroup_namespaces_init(void) subsys_initcall(cgroup_namespaces_init); #ifdef CONFIG_CGROUP_BPF -void cgroup_bpf_update(struct cgroup *cgrp, - struct bpf_prog *prog, - enum bpf_attach_type type) +int cgroup_bpf_update(struct cgroup *cgrp, struct bpf_prog *prog, + enum bpf_attach_type type, bool overridable) { struct cgroup *parent = cgroup_parent(cgrp); + int ret; mutex_lock(&cgroup_mutex); - __cgroup_bpf_update(cgrp, parent, prog, type); + ret = __cgroup_bpf_update(cgrp, parent, prog, type, overridable); mutex_unlock(&cgroup_mutex); + return ret; } #endif /* CONFIG_CGROUP_BPF */ diff --git a/samples/bpf/test_cgrp2_attach.c b/samples/bpf/test_cgrp2_attach.c index 504058631ffc..4bfcaf93fcf3 100644 --- a/samples/bpf/test_cgrp2_attach.c +++ b/samples/bpf/test_cgrp2_attach.c @@ -104,7 +104,7 @@ static int attach_filter(int cg_fd, int type, int verdict) return EXIT_FAILURE; } - ret = bpf_prog_attach(prog_fd, cg_fd, type); + ret = bpf_prog_attach(prog_fd, cg_fd, type, 0); if (ret < 0) { printf("Failed to attach prog to cgroup: '%s'\n", strerror(errno)); diff --git a/samples/bpf/test_cgrp2_attach2.c b/samples/bpf/test_cgrp2_attach2.c index 6e69be37f87f..3049b1f26267 100644 --- a/samples/bpf/test_cgrp2_attach2.c +++ b/samples/bpf/test_cgrp2_attach2.c @@ -79,11 +79,12 @@ int main(int argc, char **argv) if (join_cgroup(FOO)) goto err; - if (bpf_prog_attach(drop_prog, foo, BPF_CGROUP_INET_EGRESS)) { + if (bpf_prog_attach(drop_prog, foo, BPF_CGROUP_INET_EGRESS, 1)) { log_err("Attaching prog to /foo"); goto err; } + printf("Attached DROP prog. This ping in cgroup /foo should fail...\n"); assert(system(PING_CMD) != 0); /* Create cgroup /foo/bar, get fd, and join it */ @@ -94,24 +95,27 @@ int main(int argc, char **argv) if (join_cgroup(BAR)) goto err; + printf("Attached DROP prog. This ping in cgroup /foo/bar should fail...\n"); assert(system(PING_CMD) != 0); - if (bpf_prog_attach(allow_prog, bar, BPF_CGROUP_INET_EGRESS)) { + if (bpf_prog_attach(allow_prog, bar, BPF_CGROUP_INET_EGRESS, 1)) { log_err("Attaching prog to /foo/bar"); goto err; } + printf("Attached PASS prog. This ping in cgroup /foo/bar should pass...\n"); assert(system(PING_CMD) == 0); - if (bpf_prog_detach(bar, BPF_CGROUP_INET_EGRESS)) { log_err("Detaching program from /foo/bar"); goto err; } + printf("Detached PASS from /foo/bar while DROP is attached to /foo.\n" + "This ping in cgroup /foo/bar should fail...\n"); assert(system(PING_CMD) != 0); - if (bpf_prog_attach(allow_prog, bar, BPF_CGROUP_INET_EGRESS)) { + if (bpf_prog_attach(allow_prog, bar, BPF_CGROUP_INET_EGRESS, 1)) { log_err("Attaching prog to /foo/bar"); goto err; } @@ -121,8 +125,60 @@ int main(int argc, char **argv) goto err; } + printf("Attached PASS from /foo/bar and detached DROP from /foo.\n" + "This ping in cgroup /foo/bar should pass...\n"); assert(system(PING_CMD) == 0); + if (bpf_prog_attach(allow_prog, bar, BPF_CGROUP_INET_EGRESS, 1)) { + log_err("Attaching prog to /foo/bar"); + goto err; + } + + if (!bpf_prog_attach(allow_prog, bar, BPF_CGROUP_INET_EGRESS, 0)) { + errno = 0; + log_err("Unexpected success attaching prog to /foo/bar"); + goto err; + } + + if (bpf_prog_detach(bar, BPF_CGROUP_INET_EGRESS)) { + log_err("Detaching program from /foo/bar"); + goto err; + } + + if (!bpf_prog_detach(foo, BPF_CGROUP_INET_EGRESS)) { + errno = 0; + log_err("Unexpected success in double detach from /foo"); + goto err; + } + + if (bpf_prog_attach(allow_prog, foo, BPF_CGROUP_INET_EGRESS, 0)) { + log_err("Attaching non-overridable prog to /foo"); + goto err; + } + + if (!bpf_prog_attach(allow_prog, bar, BPF_CGROUP_INET_EGRESS, 0)) { + errno = 0; + log_err("Unexpected success attaching non-overridable prog to /foo/bar"); + goto err; + } + + if (!bpf_prog_attach(allow_prog, bar, BPF_CGROUP_INET_EGRESS, 1)) { + errno = 0; + log_err("Unexpected success attaching overridable prog to /foo/bar"); + goto err; + } + + if (!bpf_prog_attach(allow_prog, foo, BPF_CGROUP_INET_EGRESS, 1)) { + errno = 0; + log_err("Unexpected success attaching overridable prog to /foo"); + goto err; + } + + if (bpf_prog_attach(drop_prog, foo, BPF_CGROUP_INET_EGRESS, 0)) { + log_err("Attaching different non-overridable prog to /foo"); + goto err; + } + goto out; err: @@ -132,5 +188,9 @@ out: close(foo); close(bar); cleanup_cgroup_environment(); + if (!rc) + printf("PASS\n"); + else + printf("FAIL\n"); return rc; } diff --git a/samples/bpf/test_cgrp2_sock.c b/samples/bpf/test_cgrp2_sock.c index 0791b949cbe4..c3cfb23e23b5 100644 --- a/samples/bpf/test_cgrp2_sock.c +++ b/samples/bpf/test_cgrp2_sock.c @@ -75,7 +75,7 @@ int main(int argc, char **argv) return EXIT_FAILURE; } - ret = bpf_prog_attach(prog_fd, cg_fd, BPF_CGROUP_INET_SOCK_CREATE); + ret = bpf_prog_attach(prog_fd, cg_fd, BPF_CGROUP_INET_SOCK_CREATE, 0); if (ret < 0) { printf("Failed to attach prog to cgroup: '%s'\n", strerror(errno)); diff --git a/samples/bpf/test_cgrp2_sock2.c b/samples/bpf/test_cgrp2_sock2.c index 455ef0d06e93..db036077b644 100644 --- a/samples/bpf/test_cgrp2_sock2.c +++ b/samples/bpf/test_cgrp2_sock2.c @@ -55,7 +55,7 @@ int main(int argc, char **argv) } ret = bpf_prog_attach(prog_fd[filter_id], cg_fd, - BPF_CGROUP_INET_SOCK_CREATE); + BPF_CGROUP_INET_SOCK_CREATE, 0); if (ret < 0) { printf("Failed to attach prog to cgroup: '%s'\n", strerror(errno)); diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c index 3ddb58a36d3c..ae752fa4eaa7 100644 --- a/tools/lib/bpf/bpf.c +++ b/tools/lib/bpf/bpf.c @@ -168,7 +168,8 @@ int bpf_obj_get(const char *pathname) return sys_bpf(BPF_OBJ_GET, &attr, sizeof(attr)); } -int bpf_prog_attach(int prog_fd, int target_fd, enum bpf_attach_type type) +int bpf_prog_attach(int prog_fd, int target_fd, enum bpf_attach_type type, + unsigned int flags) { union bpf_attr attr; @@ -176,6 +177,7 @@ int bpf_prog_attach(int prog_fd, int target_fd, enum bpf_attach_type type) attr.target_fd = target_fd; attr.attach_bpf_fd = prog_fd; attr.attach_type = type; + attr.attach_flags = flags; return sys_bpf(BPF_PROG_ATTACH, &attr, sizeof(attr)); } diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h index a2f9853dd882..4ac6c4b84100 100644 --- a/tools/lib/bpf/bpf.h +++ b/tools/lib/bpf/bpf.h @@ -41,7 +41,8 @@ int bpf_map_delete_elem(int fd, void *key); int bpf_map_get_next_key(int fd, void *key, void *next_key); int bpf_obj_pin(int fd, const char *pathname); int bpf_obj_get(const char *pathname); -int bpf_prog_attach(int prog_fd, int attachable_fd, enum bpf_attach_type type); +int bpf_prog_attach(int prog_fd, int attachable_fd, enum bpf_attach_type type, + unsigned int flags); int bpf_prog_detach(int attachable_fd, enum bpf_attach_type type);