Segmentation Fault occured after calling setcap to v2ray

[ghost]

getcap ./v2ray
----> (no output)

./v2ray                                      
----> V2Ray 4.20.0 (V2Fly, a community-driven edition of V2Ray.) Custom
----> A unified platform for anti-censorship......
----> (blablablabla.............)

sudo setcap CAP_NET_ADMIN,CAP_NET_RAW,CAP_NET_BIND_SERVICE=eip ./v2ray

getcap ./v2ray
----> ./v2ray = cap_net_bind_service,cap_net_admin,cap_net_raw+eip

./v2ray                                      
----> [1]    75971 segmentation fault  ./v2ray

Originally posted by @lhy0403 in #57 (comment)

[ghost]

解决方案：

sudo sysctl fs.suid_dumpable=1

[ghost]

For future refrence: yggdrasil-network/yggdrasil-go#403 (comment)

[iusearch]

Write this into doc.

[ghost]

After a short talk on IRC, we came to this conclusion:

This is caused by vsyscall=none being passed to the kernel command line, and the go runtime relying on the legacy vsyscall table being present.

The go runtime is attempting to call gettimeofday() using the vdso page.

278  LEAQ 0(SP), DI
279  MOVQ $0, SI
280  MOVQ runtime·vdsoGettimeofdaySym(SB), AX
281  CALL AX
282  MOVQ 0(SP), AX // sec

However, since the legacy vsyscall table is disabled in the kernel, this ends up failing and causing a segfault.

[559159.574164] yggdrasil[1562] vsyscall attempted with vsyscall=none ip:ffffffffff600000 cs:33 sp:7ffd6f0c3e78 ax:ffffffffff600000 si:0 di:7ffd6f0c3e80
[559159.574174] yggdrasil[1562]: segfault at ffffffffff600000 ip ffffffffff600000 sp 00007ffd6f0c3e78 error 15
[559159.574178] Code: Bad RIP value.

Modern programs shouldn't rely on the vsyscall table being present and should link to linux-vdso.so.1

Edit:
The normal output of ldd yggdrasilshould be something like this

linux-vdso.so.1 (0x00007ffc3eeef000)   //this should be present 
ibpthread.so.0 => /usr/lib/libpthread.so.0 (0x00007f5df3a01000)
libc.so.6 => /usr/lib/libc.so.6 (0x00007f5df383d000)
/lib64/ld-linux-x86-64.so.2 => /usr/lib64/ld-linux-x86-64.so.2 (0x00007f5df3fd8000)

Error analyzed from: yggdrasil-network/yggdrasil-go#403 (comment)