Thread (73 messages) 73 messages, 7 authors, 2022-03-15

Re: [PATCH bpf-next v2 01/28] bpf: add new is_sys_admin_prog_type() helper

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From: Sean Young <sean@mess.org>
Date: 2022-03-09 08:27:20
Also in: bpf, linux-input, linux-kselftest, lkml

On Fri, Mar 04, 2022 at 06:28:25PM +0100, Benjamin Tissoires wrote:
LIRC_MODE2 does not really need net_admin capability, but only sys_admin.

Extract a new helper for it, it will be also used for the HID bpf
implementation.

Cc: Sean Young <sean@mess.org>
Signed-off-by: Benjamin Tissoires <redacted>
For BPF_PROG_TYPE_LIRC_MODE2, I don't think this change will break userspace.
This is called from ir-keytable(1) which is called from udev. It should have
all the necessary permissions.

In addition, the vast majority IR decoders are non-bpf. bpf ir decoders have
very few users at the moment.

Acked-by: Sean Young <sean@mess.org>


Sean
quoted hunk ↗ jump to hunk
---

new in v2
---
 kernel/bpf/syscall.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index db402ebc5570..cc570891322b 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2165,7 +2165,6 @@ static bool is_net_admin_prog_type(enum bpf_prog_type prog_type)
 	case BPF_PROG_TYPE_LWT_SEG6LOCAL:
 	case BPF_PROG_TYPE_SK_SKB:
 	case BPF_PROG_TYPE_SK_MSG:
-	case BPF_PROG_TYPE_LIRC_MODE2:
 	case BPF_PROG_TYPE_FLOW_DISSECTOR:
 	case BPF_PROG_TYPE_CGROUP_DEVICE:
 	case BPF_PROG_TYPE_CGROUP_SOCK:
@@ -2202,6 +2201,17 @@ static bool is_perfmon_prog_type(enum bpf_prog_type prog_type)
 	}
 }
 
+static bool is_sys_admin_prog_type(enum bpf_prog_type prog_type)
+{
+	switch (prog_type) {
+	case BPF_PROG_TYPE_LIRC_MODE2:
+	case BPF_PROG_TYPE_EXT: /* extends any prog */
+		return true;
+	default:
+		return false;
+	}
+}
+
 /* last field in 'union bpf_attr' used by this command */
 #define	BPF_PROG_LOAD_LAST_FIELD core_relo_rec_size
 
@@ -2252,6 +2262,8 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr)
 		return -EPERM;
 	if (is_perfmon_prog_type(type) && !perfmon_capable())
 		return -EPERM;
+	if (is_sys_admin_prog_type(type) && !capable(CAP_SYS_ADMIN))
+		return -EPERM;
 
 	/* attach_prog_fd/attach_btf_obj_fd can specify fd of either bpf_prog
 	 * or btf, we need to check which one it is
-- 
2.35.1
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