Andrew GunnersonandGitHub
a0171e3a9b
ad0044fec8 previously disabled it due to
seccomp crashes. This was caused by `golang.org/x/sys`'s
`unix.EpollWait` function using the `epoll_wait` syscall instead of the
`epoll_pwait` syscall. bionic libc implements the `epoll_wait` C wrapper
function in terms of the `epoll_pwait` syscall, so this never affected C
code.
`golang.org/x/sys` switched to the `epoll_pwait` syscall in 2016, but
only for arm64. As of v0.47.0, it now uses `epoll_pwait` for all
architectures.
Upstream bug: https://github.com/golang/go/issues/80080
Upstream fix: https://go-review.googlesource.com/c/sys/+/792700
Upstream arm64 fix from 2016:
https://go-review.googlesource.com/c/sys/+/21971
---
With this change, Syncthing no longer crashes when inotify is allowed
and enabled in the Android emulator when run inside an app context. (The
seccomp policies do not affect execution under `adb shell`.)
This is the crash that occurs if inotify is enabled without the v0.47.0
update:
```
2026-07-08 10:59:36.711202 -0400 F/DEBUG (16538): *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
2026-07-08 10:59:36.711219 -0400 F/DEBUG (16538): Build fingerprint: 'google/sdk_gphone16k_x86_64/emu64xa16k:17/CE2A.260420.019/15611780:userdebug/dev-keys'
2026-07-08 10:59:36.711224 -0400 F/DEBUG (16538): Kernel Release: '6.12.58-android16-6-gccafb60de224-ab14828483'
2026-07-08 10:59:36.711226 -0400 F/DEBUG (16538): Revision: '0'
2026-07-08 10:59:36.711228 -0400 F/DEBUG (16538): ABI: 'x86_64'
2026-07-08 10:59:36.711230 -0400 F/DEBUG (16538): Timestamp: 2026-07-08 10:59:36.617348693-0400
2026-07-08 10:59:36.711232 -0400 F/DEBUG (16538): Process uptime: 2s
2026-07-08 10:59:36.711234 -0400 F/DEBUG (16538): Page size: 16384 bytes
2026-07-08 10:59:36.711236 -0400 F/DEBUG (16538): Executable: /system/bin/app_process64
2026-07-08 10:59:36.711239 -0400 F/DEBUG (16538): Cmdline: com.chiller3.basicsync.debug
2026-07-08 10:59:36.711241 -0400 F/DEBUG (16538): pid: 16502, ppid: 436, tid: 16531, name: Thread-6 >>> com.chiller3.basicsync.debug <<<
2026-07-08 10:59:36.711243 -0400 F/DEBUG (16538): uid: 10231
2026-07-08 10:59:36.711886 -0400 F/DEBUG (16538): signal 31 (SIGSYS), code 1 (SYS_SECCOMP), fault addr --------
2026-07-08 10:59:36.711899 -0400 F/DEBUG (16538): Cause: seccomp prevented call to disallowed x86_64 system call 232
2026-07-08 10:59:36.711908 -0400 F/DEBUG (16538): rax 00000000000000e8 rbx 0000000000000078 rcx 00007372d956826e rdx 0000000000000001
2026-07-08 10:59:36.711912 -0400 F/DEBUG (16538): r8 0000000000000000 r9 0000000000000000 r10 ffffffffffffffff r11 0000000000000206
2026-07-08 10:59:36.712123 -0400 F/DEBUG (16538): r12 0000737291cc5d00 r13 000025897adcad20 r14 000025897abc7c20 r15 ffffffffffffffff
2026-07-08 10:59:36.712134 -0400 F/DEBUG (16538): rdi 0000000000000078 rsi 000025897af9ef7c
2026-07-08 10:59:36.712137 -0400 F/DEBUG (16538): rbp 000025897af9ee28 rsp 000025897af9ede8 rip 00007372d956826e err 0000000000000000
2026-07-08 10:59:36.712139 -0400 F/DEBUG (16538): 1 total frames
2026-07-08 10:59:36.712141 -0400 F/DEBUG (16538): backtrace:
2026-07-08 10:59:36.712145 -0400 F/DEBUG (16538): #00 pc 0000000000d2826e /data/app/~~s99umF1bl81-VDLSDwy30g==/com.chiller3.basicsync.debug-5Lq8YsTwbMz_SXt-F_uHaQ==/base.apk (offset 0x2e4c000)
2026-07-08 10:59:36.712431 -0400 F/DEBUG (16538): Note: To display stack pointer information, use the pbtombstone tool:
2026-07-08 10:59:36.712443 -0400 F/DEBUG (16538): pbtombstone --display-sp tombstone_XX.pb
```
Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>
Goals
Syncthing is a continuous file synchronization program. It synchronizes files between two or more computers. We strive to fulfill the goals below. The goals are listed in order of importance, the most important ones first. This is the summary version of the goal list - for more commentary, see the full Goals document.
Syncthing should be:
-
Safe From Data Loss
Protecting the user's data is paramount. We take every reasonable precaution to avoid corrupting the user's files.
-
Secure Against Attackers
Again, protecting the user's data is paramount. Regardless of our other goals, we must never allow the user's data to be susceptible to eavesdropping or modification by unauthorized parties.
-
Easy to Use
Syncthing should be approachable, understandable, and inclusive.
-
Automatic
User interaction should be required only when absolutely necessary.
-
Universally Available
Syncthing should run on every common computer. We are mindful that the latest technology is not always available to every individual.
-
For Individuals
Syncthing is primarily about empowering the individual user with safe, secure, and easy to use file synchronization.
-
Everything Else
There are many things we care about that don't make it on to the list. It is fine to optimize for these values, as long as they are not in conflict with the stated goals above.
Getting Started
Take a look at the getting started guide.
There are a few examples for keeping Syncthing running in the background on your system in the etc directory. There are also several GUI implementations for Windows, Mac, and Linux.
Docker
To run Syncthing in Docker, see the Docker README.
Getting in Touch
The first and best point of contact is the Forum. If you've found something that is clearly a bug, feel free to report it in the GitHub issue tracker.
If you believe that you’ve found a Syncthing-related security vulnerability, please report it by emailing security@syncthing.net. Do not report it in the Forum or issue tracker.
Building
Building Syncthing from source is easy. After extracting the source bundle from
a release or checking out git, you just need to run go run build.go and the
binaries are created in ./bin. There's a guide with more details on the
build process.
Signed Releases
Release binaries are GPG signed with the key available from https://syncthing.net/security/. There is also a built-in automatic upgrade mechanism (disabled in some distribution channels) which uses a compiled in ECDSA signature. macOS and Windows binaries are also code-signed.
Documentation
Please see the Syncthing documentation site [source].
All code is licensed under the MPLv2 License.