lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Fri, 31 Jul 2020 02:03:23 +0200
From:   Maciej Fijalkowski <maciej.fijalkowski@...el.com>
To:     ast@...nel.org, daniel@...earbox.net
Cc:     bpf@...r.kernel.org, netdev@...r.kernel.org, bjorn.topel@...el.com,
        magnus.karlsson@...el.com,
        Maciej Fijalkowski <maciej.fijalkowski@...el.com>
Subject: [PATCH v6 bpf-next 5/6] bpf: allow for tailcalls in BPF subprograms for x64 JIT

Relax verifier's restriction that was meant to forbid tailcall usage
when subprog count was higher than 1.

Also, do not max out the stack depth of program that utilizes tailcalls.

Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
---
 kernel/bpf/verifier.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 96a339e24e93..fefc91f350d8 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -4251,10 +4251,12 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
 	case BPF_FUNC_tail_call:
 		if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
 			goto error;
+#if !defined(CONFIG_X86_64) || !defined(CONFIG_BPF_JIT_ALWAYS_ON)
 		if (env->subprog_cnt > 1) {
 			verbose(env, "tail_calls are not allowed in programs with bpf-to-bpf calls\n");
 			return -EINVAL;
 		}
+#endif
 		break;
 	case BPF_FUNC_perf_event_read:
 	case BPF_FUNC_perf_event_output:
@@ -10387,7 +10389,9 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env)
 			 * the program array.
 			 */
 			prog->cb_access = 1;
+#if !defined(CONFIG_X86_64) || !defined(CONFIG_BPF_JIT_ALWAYS_ON)
 			env->prog->aux->stack_depth = MAX_BPF_STACK;
+#endif
 			env->prog->aux->max_pkt_offset = MAX_PACKET_OFF;
 
 			/* mark bpf_tail_call as different opcode to avoid
-- 
2.20.1

Powered by blists - more mailing lists