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https://github.com/torvalds/linux
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fs: keep struct mnt_id_req extensible
Make it extensible so that we have the liberty to reuse it in future mount-id based apis. Treat zero size as the first published struct. Signed-off-by: Christian Brauner <brauner@kernel.org>
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@ -4956,6 +4956,30 @@ static int prepare_kstatmount(struct kstatmount *ks, struct mnt_id_req *kreq,
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return 0;
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}
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static int copy_mnt_id_req(const struct mnt_id_req __user *req,
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struct mnt_id_req *kreq)
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{
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int ret;
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size_t usize;
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BUILD_BUG_ON(sizeof(struct mnt_id_req) != MNT_ID_REQ_SIZE_VER0);
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ret = get_user(usize, &req->size);
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if (ret)
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return -EFAULT;
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if (unlikely(usize > PAGE_SIZE))
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return -E2BIG;
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if (unlikely(usize < MNT_ID_REQ_SIZE_VER0))
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return -EINVAL;
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memset(kreq, 0, sizeof(*kreq));
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ret = copy_struct_from_user(kreq, sizeof(*kreq), req, usize);
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if (ret)
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return ret;
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if (kreq->spare != 0)
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return -EINVAL;
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return 0;
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}
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SYSCALL_DEFINE4(statmount, const struct mnt_id_req __user *, req,
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struct statmount __user *, buf, size_t, bufsize,
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unsigned int, flags)
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@ -4970,8 +4994,9 @@ SYSCALL_DEFINE4(statmount, const struct mnt_id_req __user *, req,
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if (flags)
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return -EINVAL;
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if (copy_from_user(&kreq, req, sizeof(kreq)))
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return -EFAULT;
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ret = copy_mnt_id_req(req, &kreq);
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if (ret)
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return ret;
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retry:
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ret = prepare_kstatmount(&ks, &kreq, buf, bufsize, seq_size);
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@ -5052,8 +5077,9 @@ SYSCALL_DEFINE4(listmount, const struct mnt_id_req __user *, req,
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if (flags)
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return -EINVAL;
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if (copy_from_user(&kreq, req, sizeof(kreq)))
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return -EFAULT;
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ret = copy_mnt_id_req(req, &kreq);
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if (ret)
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return ret;
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mnt_id = kreq.mnt_id;
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last_mnt_id = kreq.param;
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@ -184,10 +184,15 @@ struct statmount {
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* For listmount(2) @param represents the last listed mount id (or zero).
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*/
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struct mnt_id_req {
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__u32 size;
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__u32 spare;
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__u64 mnt_id;
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__u64 param;
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};
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/* List of all mnt_id_req versions. */
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#define MNT_ID_REQ_SIZE_VER0 24 /* sizeof first published struct */
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/*
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* @mask bits for statmount(2)
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*/
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