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Re: Inject custom code or data into running process
by Sayutin Dmitry Jan. 3, 2017

Jan. 3, 2017

Yes, I understand points you provide. > but a royal pain to sandbox malicious code My idea is to get some assistance from kernel on it (possible with source patch or kernel module), but I would like to implement POC [proof-of-concept] myself, before showing it to the community. Let me return back to the original question (injection of code/data) LD_PRELOAD is quite a briliant way, but will not work on statically-linked code. However it may be enough for POC. 03.01.2017, 22:40, "valdis.kletnieks(a)vt.edu" <valdis.kletnieks(a)vt.edu>: > On Tue, 03 Jan 2017 22:24:11 +0300, Sayutin Dmitry said: > >> (If you want to know motivation for this -- I want to implement some new idea on sandboxing). > > There's pretty much nothing you can do inside the process to do sandboxing > against code that doesn't want to be sandboxed. In other words, it's > easy to sandbox possibly buggy code, but a royal pain to sandbox malicious > code. > > Hint: You can lead a horse to code, but you can't force it to call it. > > For instance, using LD_PRELOAD is a good way to front-end calls to glibc > code - but it doesn't do squat against malware that issues its own syscalls > inline to avoid your front end. Sayutin Dmitry <cdkrot(a)yandex.com>

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How to build an external module in a specified directory?
by Shiyao Ma Jan. 3, 2017

Jan. 3, 2017

Hi, When building an external module, for example, given this command, all: $(MAKE) -C $(KDIR) M=$$PWD It will build the ko file in the $PWD. How to specify a location for the .ko files? Regards.

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Doubt in Eudyptula Challenge
by deeksha varshney Jan. 2, 2017

Jan. 2, 2017

Hello sir, I am not able to understand what to write in the subject line along with the ID while submitting the task 01.Please help I am getting the following reply from Little I can not understand your Subject: line, please read the introductory email and fix the subject to match exactly as it says in order for me to be able to parse it properly. Deeksha

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[MMC_SPI] CMD 18 error -84 transferring data
by Amit Mahadik Jan. 2, 2017

Jan. 2, 2017

Hello, I am using ARM (CortexA9)development board which has SPI controller running at 5MHz. I want to interface MMC card on SPI bus. I have made changes to my board.c file to include the mmc_spi driver and mentioned the Chip select, mode (MODE 0) and frequency of operation (started with 40kHz tried with 25MHz as well). The initial card detection goes well. However, there are CRC errors when the block layer tries to read the partition table. This issue is reproducible. I have attached log for reference. The card gets detected on Linux/Windows PC. The card is formatted with DOS partition (vfat single partition). Linux kernel version Used : 4.4.16 Please help me regarding this issue. Regards, Amit.

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Question about object-based reverse mapping
by Hao Lee Jan. 1, 2017

Jan. 1, 2017

Hi, all I'm currently reading "Understanding the Linux Kernel (3rd)" and I have a question about "object-based reverse mapping". This is the Figure 17-1 on page 683 : http://imgur.com/R0OtIJh As this figure shows, many vm_area_struct are in the anon_vma’s list and they share some page frames. The index field in page struct represents the offset of virtual address within the virtual memory area. What I want to know is what would happen when a page frame is shared by several vm_area_struct. If two virtual memory areas share the same page frame, it seems that page->index would be overridden because there are two vma and the variable index would be assigned two times. How the linux kernel prevent it happening. Thanks. Hao Lee

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Driver to allow DMA from user space
by Ran Shalit Dec. 31, 2016

Dec. 31, 2016

Hello, I want to use DMA from userspace. I already use dma in kernel, and now I want can create a character device which will be responsible for this. The only problem is that I want to use the same memory which was allocated in kernel with dma_alloc_coherent. Is it correct to use mmap in order to use the phsyical memory which was allocated with dma_alloc_coherent ? If it's that simple it can be surely helpful, and the simple driver which wraps dma_alloc_coherent can do the job for dmaing from userspace. In kernel: dma_buffer_info->buf_info[i].virtAddr = (uint8_t *)dma_alloc_coherent( &ti667x_pci_dev[dev_id]->dev, dma_buffer_info->buffer_size, (dma_addr_t *)&dma_buffer_info->buf_info[i].pcieAddr, GFP_KERNEL); In userspace: buf_desc[i].virtAddr = mmap(0, size_of_buffer, PROT_READ | PROT_WRITE, MAP_SHARED, pcie_drv_inst[dsp_id].dev_desc, buf_desc[i].pcieAddr); Thanks, Ran

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Re: how to periodically monitor the qdisc size ?
by Shiyao Ma Dec. 29, 2016

Dec. 29, 2016

Hi Valdis, I am in the process of doing an emulation of a dumbbell topology, on my linux box. > > I am using the RED qdsic. > > You have our condolences. RED is probably not the best choice of > qdisc, because it requires very careful tuning of multiple parameters. > I am using RED for the part of emulating a switch. Since most switches are use AQM of RED/ECN. > > You might want to investigate using fq_codel, or for very new > kernels, use the fq qdisc and the bbr congestion control method. > Yes. For the sending side, I am already using fq+bbr. -- 吾輩は猫である。ホームーページはhttps://introo.me <http://introo.me>。

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how to periodically monitor the qdisc size ?
by Shiyao Ma Dec. 29, 2016

Dec. 29, 2016

Hi, I am using the RED qdsic. I want to see how many skbuffs are in the red qdisc, and the total bytes of the skbuffs, like in every 2 seconds. Regards

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[MMC_SPI] Getting CRC error on CMD18 for MMC card on SPI
by Amit Mahadik Dec. 29, 2016

Dec. 29, 2016

Hello, I am using ARM (CortexA9)development board which has SPI controller running at 6MHz. I want to interface MMC card on SPI bus. I have made changes to my board.c file to include the mmc_spi driver and mentioned the Chip select, mode (MODE 0) and frequency of operation (started with 40kHz). The initial card detection goes well. However, there are CRC errors when the block layer tries to read the partition table.I have attached log for reference. The card gets detected on Linux based system. The card is formatted with DOS partition (single partition). Please help me regarding this issue. Regards,Amit.

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In netlink, what is interface address and what is local address.
by Douglas Su Dec. 29, 2016

Dec. 29, 2016

I am totally confused with these two addresses, don't they are the same? Can a same IP be set on different interface?

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