Messages in this thread Patch in this message | | | From | Christian Brauner <> | Subject | [PATCH v2 3/3] bpf: use copy_struct_from_user() in bpf() syscall | Date | Wed, 16 Oct 2019 02:41:38 +0200 |
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In v5.4-rc2 we added a new helper (cf. [1]) copy_struct_from_user(). This helper is intended for all codepaths that copy structs from userspace that are versioned by size. The bpf() syscall does exactly what copy_struct_from_user() is doing. Note that copy_struct_from_user() is calling min() already. So technically, the min_t() call could go. But the size is used further below so leave it.
[1]: f5a1a536fa14 ("lib: introduce copy_struct_from_user() helper") Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: bpf@vger.kernel.org Acked-by: Aleksa Sarai <cyphar@cyphar.com> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> --- /* v1 */ Link: https://lore.kernel.org/r/20191009160907.10981-4-christian.brauner@ubuntu.com
/* v2 */ - Alexei Starovoitov <ast@kernel.org>: - remove unneeded initialization --- kernel/bpf/syscall.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 45524089e15d..5db9887a8f4c 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2817,20 +2817,17 @@ static int bpf_task_fd_query(const union bpf_attr *attr, SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size) { - union bpf_attr attr = {}; + union bpf_attr attr; int err; if (sysctl_unprivileged_bpf_disabled && !capable(CAP_SYS_ADMIN)) return -EPERM; - err = bpf_check_uarg_tail_zero(uattr, sizeof(attr), size); - if (err) - return err; size = min_t(u32, size, sizeof(attr)); - /* copy attributes from user space, may be less than sizeof(bpf_attr) */ - if (copy_from_user(&attr, uattr, size) != 0) - return -EFAULT; + err = copy_struct_from_user(&attr, sizeof(attr), uattr, size); + if (err) + return err; err = security_bpf(cmd, &attr, size); if (err < 0) -- 2.23.0
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