[PATCH bpf 2/4] bpf_trace: support 32-bit kernels in bpf_kprobe_multi_link_attach
From: Eugene Syromiatnikov <hidden>
Date: 2022-05-16 18:27:53
Also in:
bpf, linux-kselftest, lkml
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [security & lsm] (security audit and enforcement using bpf), bpf [tracing], the rest, tracing · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, KP Singh, Matt Bobrowski, Song Liu, Linus Torvalds, Steven Rostedt, Masami Hiramatsu
It seems that there is no reason not to support 32-bit architectures; doing so requires a bit of rework with respect to cookies handling, however, as the current code implicitly assumes that sizeof(long) == sizeof(u64). Signed-off-by: Eugene Syromiatnikov <redacted> --- kernel/trace/bpf_trace.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index e90c4ce7..d228440 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c@@ -2405,16 +2405,12 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr struct bpf_link_primer link_primer; void __user *ucookies; unsigned long *addrs; - u32 flags, cnt, size; + u32 flags, cnt, size, cookies_size; void __user *uaddrs; u64 *cookies = NULL; void __user *usyms; int err; - /* no support for 32bit archs yet */ - if (sizeof(u64) != sizeof(void *)) - return -EOPNOTSUPP; - if (prog->expected_attach_type != BPF_TRACE_KPROBE_MULTI) return -EINVAL;
@@ -2424,6 +2420,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr uaddrs = u64_to_user_ptr(attr->link_create.kprobe_multi.addrs); usyms = u64_to_user_ptr(attr->link_create.kprobe_multi.syms); + ucookies = u64_to_user_ptr(attr->link_create.kprobe_multi.cookies); if (!!uaddrs == !!usyms) return -EINVAL;
@@ -2431,8 +2428,11 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr if (!cnt) return -EINVAL; - if (check_mul_overflow(cnt, (u32)sizeof(*addrs), &size)) + if (check_mul_overflow(cnt, (u32)sizeof(*addrs), &size) || + (ucookies && + check_mul_overflow(cnt, (u32)sizeof(*cookies), &cookies_size))) { return -EOVERFLOW; + } size = cnt * sizeof(*addrs); addrs = kvmalloc(size, GFP_KERNEL); if (!addrs)
@@ -2449,14 +2449,14 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr goto error; } - ucookies = u64_to_user_ptr(attr->link_create.kprobe_multi.cookies); if (ucookies) { - cookies = kvmalloc(size, GFP_KERNEL); + cookies_size = cnt * sizeof(*cookies); + cookies = kvmalloc(cookies_size, GFP_KERNEL); if (!cookies) { err = -ENOMEM; goto error; } - if (copy_from_user(cookies, ucookies, size)) { + if (copy_from_user(cookies, ucookies, cookies_size)) { err = -EFAULT; goto error; }
--
2.1.4