I am very familiar with editing the ramdisk of a standard boot.img but have no idea how to do so with the way this phone is set up (has a zImage, etc). Can someone point me in the right direction so we can make some great things happen for this device? Thanks in advance
I can tell you how to extract the initramfs image, but I don't think anybody has had success in inserting an altered image into the stock kernel, so it's only of use in building your own kernel. You need to search for a gzip header in the zImage, it is a sequence of three bytes: 1F8B08. Gunzip this and all data following it to get the Image file. Search that for another gzip header, which is the start of the initramfs, in the form of a gzipped cpio archive. You will need to unpack this if you want to modify it. Be aware that it contains absolute pathnames and that cpio will cheerfully and silently extract these to the root of your filesystem if to don't explicitly tell it not to.
Sent from my SAMSUNG-SGH-I897 using XDA App
Hey,
Has anyone been able to get a _real_ dump of bpsw from the Droid X? I'm using dd to dump /dev/block/mmcblk1p14, which I suspect is bpsw, but I'm getting a file with all zero's.
Also, does anyone have a partition table mapping identifying which mmc block device corresponds to which partition (i.e. cdt, sp, etc...).
Thanks.
Hey guys/gals. I'm doing some new development on the Nexus 10, and I need to enable Verity for the /system partition. This poses a problem. The partition is already the full length, and I need to truncate it, so that I can store the hash table, metadata, etc.
As you probably know, the /system partition is an ext4 partition, and parted doesn't support that. So, being as I have complete control over the device, I can do almost anything to solve this problem.
So, here are some questions that I have:
Where are the partitions initialized for a blank device?
Is there a tool that would allow me to modify the sizes of ext4 partitions?
I'm really hoping someone here knows the answers to either of those. Lots of googling has turned up nothing.
If this isn't the right forum to ask this question, please point me to the correct one! I just want an answer, it doesn't have to be specific to the Nexus 10.
FrankRizzo890 said:
If this isn't the right forum to ask this question, please point me to the correct one! I just want an answer, it doesn't have to be specific to the Nexus 10.
Click to expand...
Click to collapse
The answer is that I misunderstood what I needed to do. It's NOT the partition that needs to be adjusted for Verity, it's the FILESYSTEM. And, only if the filesystem fills up the partition.
Anyone know what block does the modem.bin write to?
azpunkster said:
Anyone know what block does the modem.bin write to?
Click to expand...
Click to collapse
do you mean "which partition does Odin write the "modem.bin" file to during flashes?
If so, then
ls -l /dev/block/platform/msm_sdcc.1/by-name
will give you the answer, e.g.
lrwxrwxrwx 1 root root 20 1971-06-12 13:06 modem -> /dev/block/mmcblk0p2
(Note that partition mapping is not universally the same on every phone; the above applies to the SM-N900V. It might be also true of other Note 3 variants, but you shouldn't take that for granted)
If you mean "when the code in modem.bin is running on the CP, where does it store its' private data?", well that's a different question altogether. I know that there are two partitions (can't remember right now but can find it in my notes if you like) that seem to get modified with jibberish every time the phone boots, but I don't think the answer to the 2nd question is completely known (it may involve the rpmb - a hardware "protected" area of the flash chip).
.
Hi all,
has anyone been able to do this? Following the guide here, no longer works for Android N. The phone boots, but ignores all changes to system. How do I modify both build.prop and hosts? It seems that there are now possibly two system partitions?
Thanks!
Same issue on Nexus 5X
No answer on this? How is it that nobody else seems to be having this issue?
What I've done
It looks to me like everyone has moved to systemless and the /system partition cannot be adequately modified in this way anymore.
Maybe this will help others:
I was modifying the system directory for two reasons: 1. modify /system/etc/hosts to remove ads and modifying build.prop to increase lcd.density. I found that here are the alternatives for each:
Removing Ads
Using something similar to AdAway_systemless_hosts_v2.zip (google it for a copy) and modifying the hosts file in that zip file to be the one I use (and rezipping, deploying on the Android device). This basically mounts over /system/etc/hosts with a custom hosts file instead of actually modifying the system specific hosts file which is no longer writable.
The alternative is to use Netguard which routes non https network traffic through a private VPN where you can block ads according to a hosts file. This seems to work OK, but I have noticed that websites seem to take longer to load.
Modifying lcd.density
You can use the same trick as AdAway_systemless_hosts_v2.zip uses, but modify it to also mount a modified copy of build.prop. Alternatively just use the Android N Display settings that are small (what I did anyhow).
I have been able to edit build.prop and still maintain systemless root.
Sent from my Nexus 6P using XDA-Developers mobile app
I was able to modify my system partition; by installing busy box to /su/xbin and running "su busybox mount -o rw,remount system" (no quotes) in material terminal with root
ArminasAnarion said:
I was able to modify my system partition; by installing busy box to /su/xbin and running "su busybox mount -o rw,remount system" (no quotes) in material terminal with root
Click to expand...
Click to collapse
Have you been able to do this with simply fastboot boot <twrp-image>, mounting system in rw mode and modifying it? I did that as I didn't want to root the phone, and while it looks like it did the write, it does not affect the system partition that is used by the phone after boot. I think there are two system partitions, and twrp mounts only one in rw mode. It does seem like it may be possible to do what you say using adb though after the phone is fully booted up. I'll try that!
dontblinkwatchout said:
Have you been able to do this with simply fastboot boot <twrp-image>, mounting system in rw mode and modifying it? I did that as I didn't want to root the phone, and while it looks like it did the write, it does not affect the system partition that is used by the phone after boot. I think there are two system partitions, and twrp mounts only one in rw mode. It does seem like it may be possible to do what you say using adb though after the phone is fully booted up. I'll try that!
Click to expand...
Click to collapse
I had the same problem. I don't want to root but I do make a few changes to my /system partition through adb in recovery such as the hosts file and some font files (namely the Emoji font file). I had modified stock boot image to not enforce encryption. I would boot back up into the system and couldn't see any changes made. The only thing I found that worked was installing a custom kernel (I use ElementalX). After that, changes I made to /system in TWRP were reflected in the OS. I don't know enough about kernel development to understand why on (mostly) stock kernel my changes couldn't be seen but on a custom one they were.
I never had this "problem" prior to Nougat.
Same issue here. Something has changed with how this is handled in Nougat.
I don't want to root just to overwrite the hosts file...
I'll keep debugging but my capability in this is definitely limited!
I use a similar approach as described in the OP's linked guide except I use my own recovery image that I compiled as an engineering build from source, and I am also experiencing the same behavior. Modifying the hosts file seems to have no impact on the system though the changes persist. Comparing the host file I installed and the host file from the latest Nexus 5X image with 'ls -lZ' the SELinux info looks to be the same. The only information that appears to differ is the modified date and one additional line in the file itself for testing. I thought I was doing something wrong with my hosts file, even though I have been using this approach since Android 6.0. However, I agree, it appears that changes to system are being ignored. Further, changing the system partition no longer shows the red warning at boot about the system being corrupted.
---------- Post added at 09:58 PM ---------- Previous post was at 09:38 PM ----------
DanRyb;68654939 I would boot back up into the system and couldn't see any changes made.[/QUOTE said:
Oooh. You're right. Neither /etc/hosts or /system/etc/hosts is modified in the booted OS after I modify it from live image, but the change is retained when I reboot into live image and mount system. Hmm, so either:
1) Need to figure out where the the system files are being loaded from and modify them from live image if possible
2) Use a mechanism similar to what dontblinkwatchout described AdAway is using of having a custom mount setup (have to reverse engineer AdAway I guess to see what it's doing)
3) ?
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Click to collapse
There's absolutely no way to modify or mount system partition r+w unless you disable dm-verity
Enviado desde mi Nexus 6P mediante Tapatalk
alexiuss said:
There's absolutely no way to modify or mount system partition r+w unless you disable dm-verity
Enviado desde mi Nexus 6P mediante Tapatalk
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Click to collapse
dm-verity has been around since Android 4.4. Are you saying there is something new around this in Android 7.0?
You can modify the system partition by compiling an engineering build of Android and booting it, then mounting the system partition and modifying it. I've been doing this to update the hosts file since Android 6.0 for every OTA update (since more recently OTA updates bomb out unless you reflash the clean "uncorrupted" system.img first). Changing the system image before Android 7.0 did result in an extra screen with a red warning about a corrupted something or other (I'm sure because dm-verity checking failed). Regardless, you can still change the system partition, the information just no longer seems to be used, which is a bit perplexing to me atm.
crashenx said:
dm-verity has been around since Android 4.4. Are you saying there is something new around this in Android 7.0?
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Click to collapse
Android 7.0 introduced redundant bits for reed solomon forward error correction into the system and vendor partitions and code in the kernel to perform the error correction.
Your changes are being written to emmc but when you boot with 7.0 kernel with dm-verity enabled your changes are being treated as data corruption and on-the-fly error corrected back to original.
You can see your changes if you boot into twrp because it has dm-verity disabled. However if you boot into android with dm-verity enabled it will look like original image again even though your changes are technically still there.
It took me a day to figure out what was really going on because i initially had no idea they added this feature to Android N.
The simple way to disable dm-verity is to install SuperSU, but you can also accomplish the same patching your own kernel, installing pre-patched kernel, installing custom kernel, etc.
sfhub said:
Android 7.0 introduced redundant bits for reed solomon forward error correction into the system and vendor partitions and code in the kernel to perform the error correction.
Your changes are being written to emmc but when you boot with 7.0 kernel with dm-verity enabled your changes are being treated as data corruption and on-the-fly error corrected back to original.
You can see your changes if you boot into twrp because it has dm-verity disabled. However if you boot into android with dm-verity enabled it will look like original image again even though your changes are technically still there.
It took me a day to figure out what was really going on because i initially had no idea they added this feature to Android N.
The simple way to disable dm-verity is to install SuperSU, but you can also accomplish the same patching your own kernel, installing pre-patched kernel, installing custom kernel, etc.
Click to expand...
Click to collapse
That's good info and makes total sense. Thanks! Pretty neat actually, just a bummer for me.
Yeah so SuperSU path is not really one I want to pursue. I could learn how to update the dm-verity shas used for verification. That'd probably be the most secure, but it's gonna be a PITA I bet. I imagine I'd need to compile my own image similar to how I made my live image and update a few things. Might have to deal with encryption which is probably an even bigger headache. Also, I bet it would break OTA and have to reflash to update, though that's true now.
I'm really curious what AdAway is doing. Maybe I should pursue reverse engineering that.
I really appreciate you pointing us in the right direction.
I am glad found this thread..willing to assist here without permanent root..
Ericarthurc said:
I was able to modify my system partition; by installing busy box to /su/xbin and running "su busybox mount -o rw,remount system" (no quotes) in material terminal with root
Click to expand...
Click to collapse
I was trying to create a /system/xbin/post-boot but couldn't remount /system, and so I added busybox to the front of my command. I am not using adb so I cut that part off. Thanks a lot!