On Fri, 26 Feb 2021 at 16:32, Mathieu Desnoyers
[off-list ref] wrote:
----- On Feb 26, 2021, at 8:51 AM, Piotr Figiel figiel@google.com wrote:
[...]
quoted
---
v2:
Applied review comments:
- changed return value from the ptrace request to the size of the
configuration structure
- expanded configuration structure with the flags field and
the rseq abi structure size
[...]
quoted
+#define PTRACE_GET_RSEQ_CONFIGURATION 0x420f
+
+struct ptrace_rseq_configuration {
+ __u64 rseq_abi_pointer;
+ __u32 rseq_abi_size;
+ __u32 signature;
+ __u32 flags;
+ __u32 pad;
+};
+
[...]
quoted
+#ifdef CONFIG_RSEQ
+static long ptrace_get_rseq_configuration(struct task_struct *task,
+ unsigned long size, void __user *data)
+{
+ struct ptrace_rseq_configuration conf = {
+ .rseq_abi_pointer = (u64)(uintptr_t)task->rseq,
+ .rseq_abi_size = sizeof(*task->rseq),
+ .signature = task->rseq_sig,
+ .flags = 0,
+ };
+
+ size = min_t(unsigned long, size, sizeof(conf));
+ if (copy_to_user(data, &conf, size))
+ return -EFAULT;
+ return sizeof(conf);
+}
I think what Florian was after would be:
struct ptrace_rseq_configuration {
__u32 size; /* size of struct ptrace_rseq_configuration */
__u32 flags;
__u64 rseq_abi_pointer;
__u32 signature;
__u32 pad;
};
where:
.size = sizeof(struct ptrace_rseq_configuration),
This way, the configuration structure can be expanded in the future. The
rseq ABI structure is by definition fixed-size, so there is no point in
having its size here.
Florian, did I understand your request correctly, or am I missing your point ?
In this case returning sizeof(conf) would serve the same purpose, wouldn't it?
Best Regards
Michał Mirosław
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