[PATCH v2 09/10] bpf: Add size validation to bpf_sock_addr_set_sun_path()
From: Kees Cook <kees@kernel.org>
Date: 2025-10-14 22:43:35
Also in:
bpf, linux-hardening, lkml
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [networking] (tcx & tc bpf, sock_addr), networking [general], the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Add defensive size validation to bpf_sock_addr_set_sun_path() before
writing to the sockaddr buffer. While the underlying buffer is guaranteed
to be sockaddr_storage (128 bytes) from the bind() syscall path, the
function should validate that "sa_kern->uaddrlen" is sufficient for the
sockaddr_un structure being written.
The validation checks that the available buffer size ("sa_kern->uaddrlen")
can accommodate both the sockaddr_un header and the requested path length
before performing the memcpy() operation.
Signed-off-by: Kees Cook <kees@kernel.org>
---
net/core/filter.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index b96b5ffc7eb3..fa6c5baf0bf3 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c@@ -12089,6 +12089,7 @@ __bpf_kfunc int bpf_sock_addr_set_sun_path(struct bpf_sock_addr_kern *sa_kern, const u8 *sun_path, u32 sun_path__sz) { struct sockaddr_un *un; + size_t required_size; if (sa_kern->sk->sk_family != AF_UNIX) return -EINVAL;
@@ -12099,9 +12100,14 @@ __bpf_kfunc int bpf_sock_addr_set_sun_path(struct bpf_sock_addr_kern *sa_kern, if (sun_path__sz == 0 || sun_path__sz > UNIX_PATH_MAX) return -EINVAL; + /* Validate that the buffer is large enough for sockaddr_un + path */ + required_size = offsetof(struct sockaddr_un, sun_path) + sun_path__sz; + if (sa_kern->uaddrlen < required_size) + return -EINVAL; + un = (struct sockaddr_un *)sa_kern->uaddr; memcpy(un->sun_path, sun_path, sun_path__sz); - sa_kern->uaddrlen = offsetof(struct sockaddr_un, sun_path) + sun_path__sz; + sa_kern->uaddrlen = required_size; return 0; }
--
2.34.1