default with systemd: bitbake secure-core-image-minimal -e | grep USE_DEVFS USE_DEVFS="1" By default, YP is configured with USE_DEVFS= “1”, and the owner of devices if “root” with 0600 permissions. ... but there are also groups which allow access of non root to various devices - a typical example is the dialout group ... also not all of them are with 0600 permissions drwxr-xr-x 16 root root 3.3K Sep 26 17:41 . drwxr-xr-x 17 root root 1.0K Sep 26 17:36 .. crw-r--r-- 1 root root 10, 235 Sep 26 17:41 autofs drwxr-xr-x 2 root root 560 Sep 26 17:41 block drwxr-xr-x 2 root root 60 Sep 26 17:41 bsg crw-rw---- 1 root disk 10, 234 Sep 26 17:41 btrfs-control drwxr-xr-x 3 root root 60 Sep 26 17:41 bus lrwxrwxrwx 1 root root 3 Sep 26 17:41 cdrom -> sr0 drwxr-xr-x 2 root root 2.7K Sep 26 17:41 char crw------- 1 root root 5, 1 Sep 26 17:41 console drwxr-xr-x 6 root root 120 Sep 26 17:41 cpu crw------- 1 root root 10, 125 Sep 26 17:41 cpu_dma_latency crw------- 1 root root 10, 203 Sep 26 17:41 cuse drwxr-xr-x 6 root root 120 Sep 26 17:41 disk drwxr-xr-x 3 root root 80 Sep 26 17:41 dri crw-rw---- 1 root video 29, 0 Sep 26 17:41 fb0 lrwxrwxrwx 1 root root 13 Sep 26 17:41 fd -> /proc/self/fd crw-rw-rw- 1 root root 1, 7 Sep 26 17:41 full crw-rw-rw- 1 root root 10, 229 Sep 26 17:41 fuse crw------- 1 root root 10, 228 Sep 26 17:41 hpet crw------- 1 root root 10, 183 Sep 26 17:41 hwrng lrwxrwxrwx 1 root root 12 Sep 26 17:41 initctl -> /run/initctl drwxr-xr-x 4 root root 180 Sep 26 17:41 input crw-r--r-- 1 root root 1, 11 Sep 26 17:41 kmsg lrwxrwxrwx 1 root root 28 Sep 26 17:41 log -> /run/systemd/journal/dev-log crw-rw---- 1 root disk 10, 237 Sep 26 17:41 loop-control brw-rw---- 1 root disk 7, 0 Sep 26 17:41 loop0 brw-rw---- 1 root disk 7, 1 Sep 26 17:41 loop1 brw-rw---- 1 root disk 7, 2 Sep 26 17:41 loop2 brw-rw---- 1 root disk 7, 3 Sep 26 17:41 loop3 brw-rw---- 1 root disk 7, 4 Sep 26 17:41 loop4 brw-rw---- 1 root disk 7, 5 Sep 26 17:41 loop5 brw-rw---- 1 root disk 7, 6 Sep 26 17:41 loop6 brw-rw---- 1 root disk 7, 7 Sep 26 17:41 loop7 drwxr-xr-x 2 root root 60 Sep 26 17:41 mapper drwxrwxrwt 2 root root 40 Sep 26 17:41 mqueue drwxr-xr-x 2 root root 60 Sep 26 17:41 net crw-rw-rw- 1 root root 1, 3 Sep 26 17:41 null crw-r----- 1 root kmem 1, 4 Sep 26 17:41 port crw------- 1 root root 108, 0 Sep 26 17:41 ppp crw-rw-rw- 1 root tty 5, 2 Sep 26 17:41 ptmx drwxr-xr-x 2 root root 0 Sep 26 17:41 pts brw-rw---- 1 root disk 1, 0 Sep 26 17:41 ram0 brw-rw---- 1 root disk 1, 1 Sep 26 17:41 ram1 brw-rw---- 1 root disk 1, 10 Sep 26 17:41 ram10 brw-rw---- 1 root disk 1, 11 Sep 26 17:41 ram11 brw-rw---- 1 root disk 1, 12 Sep 26 17:41 ram12 brw-rw---- 1 root disk 1, 13 Sep 26 17:41 ram13 brw-rw---- 1 root disk 1, 14 Sep 26 17:41 ram14 brw-rw---- 1 root disk 1, 15 Sep 26 17:41 ram15 brw-rw---- 1 root disk 1, 2 Sep 26 17:41 ram2 brw-rw---- 1 root disk 1, 3 Sep 26 17:41 ram3 brw-rw---- 1 root disk 1, 4 Sep 26 17:41 ram4 brw-rw---- 1 root disk 1, 5 Sep 26 17:41 ram5 brw-rw---- 1 root disk 1, 6 Sep 26 17:41 ram6 brw-rw---- 1 root disk 1, 7 Sep 26 17:41 ram7 brw-rw---- 1 root disk 1, 8 Sep 26 17:41 ram8 brw-rw---- 1 root disk 1, 9 Sep 26 17:41 ram9 crw-rw-rw- 1 root root 1, 8 Sep 26 17:41 random crw-rw-r-- 1 root root 10, 242 Sep 26 17:41 rfkill lrwxrwxrwx 1 root root 4 Sep 26 17:41 rtc -> rtc0 crw------- 1 root root 254, 0 Sep 26 17:41 rtc0 drwxrwxrwt 2 root root 40 Sep 26 17:41 shm drwxr-xr-x 2 root root 80 Sep 26 17:41 snd brw-rw---- 1 root cdrom 11, 0 Sep 26 17:41 sr0 lrwxrwxrwx 1 root root 15 Sep 26 17:41 stderr -> /proc/self/fd/2 lrwxrwxrwx 1 root root 15 Sep 26 17:41 stdin -> /proc/self/fd/0 lrwxrwxrwx 1 root root 15 Sep 26 17:41 stdout -> /proc/self/fd/1 crw-rw-rw- 1 root tty 5, 0 Sep 26 17:43 tty crw--w---- 1 root tty 4, 0 Sep 26 17:41 tty0 crw--w---- 1 root tty 4, 1 Sep 26 17:41 tty1 crw--w---- 1 root tty 4, 10 Sep 26 17:41 tty10 crw--w---- 1 root tty 4, 11 Sep 26 17:41 tty11 crw--w---- 1 root tty 4, 12 Sep 26 17:41 tty12 crw--w---- 1 root tty 4, 13 Sep 26 17:41 tty13 crw--w---- 1 root tty 4, 14 Sep 26 17:41 tty14 crw--w---- 1 root tty 4, 15 Sep 26 17:41 tty15 crw--w---- 1 root tty 4, 16 Sep 26 17:41 tty16 crw--w---- 1 root tty 4, 17 Sep 26 17:41 tty17 crw--w---- 1 root tty 4, 18 Sep 26 17:41 tty18 crw--w---- 1 root tty 4, 19 Sep 26 17:41 tty19 crw--w---- 1 root tty 4, 2 Sep 26 17:41 tty2 crw--w---- 1 root tty 4, 20 Sep 26 17:41 tty20 crw--w---- 1 root tty 4, 21 Sep 26 17:41 tty21 crw--w---- 1 root tty 4, 22 Sep 26 17:41 tty22 crw--w---- 1 root tty 4, 23 Sep 26 17:41 tty23 crw--w---- 1 root tty 4, 24 Sep 26 17:41 tty24 crw--w---- 1 root tty 4, 25 Sep 26 17:41 tty25 crw--w---- 1 root tty 4, 26 Sep 26 17:41 tty26 crw--w---- 1 root tty 4, 27 Sep 26 17:41 tty27 crw--w---- 1 root tty 4, 28 Sep 26 17:41 tty28 crw--w---- 1 root tty 4, 29 Sep 26 17:41 tty29 crw--w---- 1 root tty 4, 3 Sep 26 17:41 tty3 crw--w---- 1 root tty 4, 30 Sep 26 17:41 tty30 crw--w---- 1 root tty 4, 31 Sep 26 17:41 tty31 crw--w---- 1 root tty 4, 32 Sep 26 17:41 tty32 crw--w---- 1 root tty 4, 33 Sep 26 17:41 tty33 crw--w---- 1 root tty 4, 34 Sep 26 17:41 tty34 crw--w---- 1 root tty 4, 35 Sep 26 17:41 tty35 crw--w---- 1 root tty 4, 36 Sep 26 17:41 tty36 crw--w---- 1 root tty 4, 37 Sep 26 17:41 tty37 crw--w---- 1 root tty 4, 38 Sep 26 17:41 tty38 crw--w---- 1 root tty 4, 39 Sep 26 17:41 tty39 crw--w---- 1 root tty 4, 4 Sep 26 17:41 tty4 crw--w---- 1 root tty 4, 40 Sep 26 17:41 tty40 crw--w---- 1 root tty 4, 41 Sep 26 17:41 tty41 crw--w---- 1 root tty 4, 42 Sep 26 17:41 tty42 crw--w---- 1 root tty 4, 43 Sep 26 17:41 tty43 crw--w---- 1 root tty 4, 44 Sep 26 17:41 tty44 crw--w---- 1 root tty 4, 45 Sep 26 17:41 tty45 crw--w---- 1 root tty 4, 46 Sep 26 17:41 tty46 crw--w---- 1 root tty 4, 47 Sep 26 17:41 tty47 crw--w---- 1 root tty 4, 48 Sep 26 17:41 tty48 crw--w---- 1 root tty 4, 49 Sep 26 17:41 tty49 crw--w---- 1 root tty 4, 5 Sep 26 17:41 tty5 crw--w---- 1 root tty 4, 50 Sep 26 17:41 tty50 crw--w---- 1 root tty 4, 51 Sep 26 17:41 tty51 crw--w---- 1 root tty 4, 52 Sep 26 17:41 tty52 crw--w---- 1 root tty 4, 53 Sep 26 17:41 tty53 crw--w---- 1 root tty 4, 54 Sep 26 17:41 tty54 crw--w---- 1 root tty 4, 55 Sep 26 17:41 tty55 crw--w---- 1 root tty 4, 56 Sep 26 17:41 tty56 crw--w---- 1 root tty 4, 57 Sep 26 17:41 tty57 crw--w---- 1 root tty 4, 58 Sep 26 17:41 tty58 crw--w---- 1 root tty 4, 59 Sep 26 17:41 tty59 crw--w---- 1 root tty 4, 6 Sep 26 17:41 tty6 crw--w---- 1 root tty 4, 60 Sep 26 17:41 tty60 crw--w---- 1 root tty 4, 61 Sep 26 17:41 tty61 crw--w---- 1 root tty 4, 62 Sep 26 17:41 tty62 crw--w---- 1 root tty 4, 63 Sep 26 17:41 tty63 crw--w---- 1 root tty 4, 7 Sep 26 17:41 tty7 crw--w---- 1 root tty 4, 8 Sep 26 17:41 tty8 crw--w---- 1 root tty 4, 9 Sep 26 17:41 tty9 crw------- 1 root tty 4, 64 Sep 26 17:51 ttyS0 crw--w---- 1 root tty 4, 65 Sep 26 17:41 ttyS1 crw-rw---- 1 root dialout 4, 66 Sep 26 17:41 ttyS2 crw-rw---- 1 root dialout 4, 67 Sep 26 17:41 ttyS3 crw------- 1 root root 10, 223 Sep 26 17:41 uinput crw-rw-rw- 1 root root 1, 9 Sep 26 17:41 urandom crw-rw---- 1 root tty 7, 0 Sep 26 17:41 vcs crw-rw---- 1 root tty 7, 1 Sep 26 17:41 vcs1 crw-rw---- 1 root tty 7, 2 Sep 26 17:41 vcs2 crw-rw---- 1 root tty 7, 3 Sep 26 17:41 vcs3 crw-rw---- 1 root tty 7, 4 Sep 26 17:41 vcs4 crw-rw---- 1 root tty 7, 5 Sep 26 17:41 vcs5 crw-rw---- 1 root tty 7, 6 Sep 26 17:41 vcs6 crw-rw---- 1 root tty 7, 128 Sep 26 17:41 vcsa crw-rw---- 1 root tty 7, 129 Sep 26 17:41 vcsa1 crw-rw---- 1 root tty 7, 130 Sep 26 17:41 vcsa2 crw-rw---- 1 root tty 7, 131 Sep 26 17:41 vcsa3 crw-rw---- 1 root tty 7, 132 Sep 26 17:41 vcsa4 crw-rw---- 1 root tty 7, 133 Sep 26 17:41 vcsa5 crw-rw---- 1 root tty 7, 134 Sep 26 17:41 vcsa6 crw-rw---- 1 root tty 7, 64 Sep 26 17:41 vcsu crw-rw---- 1 root tty 7, 65 Sep 26 17:41 vcsu1 crw-rw---- 1 root tty 7, 66 Sep 26 17:41 vcsu2 crw-rw---- 1 root tty 7, 67 Sep 26 17:41 vcsu3 crw-rw---- 1 root tty 7, 68 Sep 26 17:41 vcsu4 crw-rw---- 1 root tty 7, 69 Sep 26 17:41 vcsu5 crw-rw---- 1 root tty 7, 70 Sep 26 17:41 vcsu6 brw-rw---- 1 root disk 253, 0 Sep 26 17:41 vda crw------- 1 root root 10, 127 Sep 26 17:41 vga_arbiter crw-rw-rw- 1 root root 10, 126 Sep 26 17:41 vsock crw-rw-rw- 1 root root 1, 5 Sep 26 17:41 zero sysv + rust coreutils: drwxr-xr-x 15 root root 3.0K Sep 26 18:09 . drwxr-xr-x 17 root root 1.0K Sep 26 18:09 .. crw-r--r-- 1 root root 10, 235 Sep 26 18:09 autofs drwxr-xr-x 2 root root 560 Sep 26 18:09 block drwxr-xr-x 2 root root 60 Sep 26 18:09 bsg crw-rw---- 1 root disk 10, 234 Sep 26 18:09 btrfs-control drwxr-xr-x 3 root root 60 Sep 26 18:09 bus lrwxrwxrwx 1 root root 3 Sep 26 18:09 cdrom -> sr0 drwxr-xr-x 2 root root 2.4K Sep 26 18:09 char crw------- 1 root root 5, 1 Sep 26 18:09 console drwxr-xr-x 6 root root 120 Sep 26 18:09 cpu crw------- 1 root root 10, 125 Sep 26 18:09 cpu_dma_latency crw------- 1 root root 10, 203 Sep 26 18:09 cuse drwxr-xr-x 5 root root 100 Sep 26 18:09 disk drwxr-xr-x 3 root root 80 Sep 26 18:09 dri crw-rw---- 1 root video 29, 0 Sep 26 18:09 fb0 lrwxrwxrwx 1 root root 13 Sep 26 18:09 fd -> /proc/self/fd crw-rw-rw- 1 root root 1, 7 Sep 26 18:09 full crw-rw-rw- 1 root root 10, 229 Sep 26 18:09 fuse crw------- 1 root root 10, 228 Sep 26 18:09 hpet crw------- 1 root root 10, 183 Sep 26 18:09 hwrng prw------- 1 root root 0 Sep 26 18:09 initctl drwxr-xr-x 4 root root 180 Sep 26 18:09 input crw-r--r-- 1 root root 1, 11 Sep 26 18:09 kmsg srw-rw-rw- 1 root root 0 Sep 26 18:09 log crw-rw---- 1 root disk 10, 237 Sep 26 18:09 loop-control brw-rw---- 1 root disk 7, 0 Sep 26 18:09 loop0 brw-rw---- 1 root disk 7, 1 Sep 26 18:09 loop1 brw-rw---- 1 root disk 7, 2 Sep 26 18:09 loop2 brw-rw---- 1 root disk 7, 3 Sep 26 18:09 loop3 brw-rw---- 1 root disk 7, 4 Sep 26 18:09 loop4 brw-rw---- 1 root disk 7, 5 Sep 26 18:09 loop5 brw-rw---- 1 root disk 7, 6 Sep 26 18:09 loop6 brw-rw---- 1 root disk 7, 7 Sep 26 18:09 loop7 drwxr-xr-x 2 root root 60 Sep 26 18:09 mapper lrwxrwxrwx 1 root root 12 Sep 26 18:09 mtab -> /proc/mounts drwxr-xr-x 2 root root 60 Sep 26 18:09 net crw-rw-rw- 1 root root 1, 3 Sep 26 18:09 null crw-r----- 1 root kmem 1, 4 Sep 26 18:09 port crw------- 1 root root 108, 0 Sep 26 18:09 ppp crw-rw-rw- 1 root tty 5, 2 Sep 26 18:09 ptmx drwxr-xr-x 2 root root 0 Sep 26 18:09 pts brw-rw---- 1 root disk 1, 0 Sep 26 18:09 ram0 brw-rw---- 1 root disk 1, 1 Sep 26 18:09 ram1 brw-rw---- 1 root disk 1, 10 Sep 26 18:09 ram10 brw-rw---- 1 root disk 1, 11 Sep 26 18:09 ram11 brw-rw---- 1 root disk 1, 12 Sep 26 18:09 ram12 brw-rw---- 1 root disk 1, 13 Sep 26 18:09 ram13 brw-rw---- 1 root disk 1, 14 Sep 26 18:09 ram14 brw-rw---- 1 root disk 1, 15 Sep 26 18:09 ram15 brw-rw---- 1 root disk 1, 2 Sep 26 18:09 ram2 brw-rw---- 1 root disk 1, 3 Sep 26 18:09 ram3 brw-rw---- 1 root disk 1, 4 Sep 26 18:09 ram4 brw-rw---- 1 root disk 1, 5 Sep 26 18:09 ram5 brw-rw---- 1 root disk 1, 6 Sep 26 18:09 ram6 brw-rw---- 1 root disk 1, 7 Sep 26 18:09 ram7 brw-rw---- 1 root disk 1, 8 Sep 26 18:09 ram8 brw-rw---- 1 root disk 1, 9 Sep 26 18:09 ram9 crw-rw-rw- 1 root root 1, 8 Sep 26 18:09 random crw-rw-r-- 1 root root 10, 242 Sep 26 18:09 rfkill lrwxrwxrwx 1 root root 4 Sep 26 18:09 rtc -> rtc0 crw------- 1 root root 254, 0 Sep 26 18:09 rtc0 drwxrwxrwt 2 root root 40 Sep 26 18:09 shm drwxr-xr-x 2 root root 80 Sep 26 18:09 snd brw-rw---- 1 root cdrom 11, 0 Sep 26 18:09 sr0 lrwxrwxrwx 1 root root 15 Sep 26 18:09 stderr -> /proc/self/fd/2 lrwxrwxrwx 1 root root 15 Sep 26 18:09 stdin -> /proc/self/fd/0 lrwxrwxrwx 1 root root 15 Sep 26 18:09 stdout -> /proc/self/fd/1 crw-rw-rw- 1 root tty 5, 0 Sep 26 18:09 tty crw--w---- 1 root tty 4, 0 Sep 26 18:09 tty0 crw--w---- 1 root root 4, 1 Sep 26 18:09 tty1 crw--w---- 1 root tty 4, 10 Sep 26 18:09 tty10 crw--w---- 1 root tty 4, 11 Sep 26 18:09 tty11 crw--w---- 1 root tty 4, 12 Sep 26 18:09 tty12 crw--w---- 1 root tty 4, 13 Sep 26 18:09 tty13 crw--w---- 1 root tty 4, 14 Sep 26 18:09 tty14 crw--w---- 1 root tty 4, 15 Sep 26 18:09 tty15 crw--w---- 1 root tty 4, 16 Sep 26 18:09 tty16 crw--w---- 1 root tty 4, 17 Sep 26 18:09 tty17 crw--w---- 1 root tty 4, 18 Sep 26 18:09 tty18 crw--w---- 1 root tty 4, 19 Sep 26 18:09 tty19 crw--w---- 1 root tty 4, 2 Sep 26 18:09 tty2 crw--w---- 1 root tty 4, 20 Sep 26 18:09 tty20 crw--w---- 1 root tty 4, 21 Sep 26 18:09 tty21 crw--w---- 1 root tty 4, 22 Sep 26 18:09 tty22 crw--w---- 1 root tty 4, 23 Sep 26 18:09 tty23 crw--w---- 1 root tty 4, 24 Sep 26 18:09 tty24 crw--w---- 1 root tty 4, 25 Sep 26 18:09 tty25 crw--w---- 1 root tty 4, 26 Sep 26 18:09 tty26 crw--w---- 1 root tty 4, 27 Sep 26 18:09 tty27 crw--w---- 1 root tty 4, 28 Sep 26 18:09 tty28 crw--w---- 1 root tty 4, 29 Sep 26 18:09 tty29 crw--w---- 1 root tty 4, 3 Sep 26 18:09 tty3 crw--w---- 1 root tty 4, 30 Sep 26 18:09 tty30 crw--w---- 1 root tty 4, 31 Sep 26 18:09 tty31 crw--w---- 1 root tty 4, 32 Sep 26 18:09 tty32 crw--w---- 1 root tty 4, 33 Sep 26 18:09 tty33 crw--w---- 1 root tty 4, 34 Sep 26 18:09 tty34 crw--w---- 1 root tty 4, 35 Sep 26 18:09 tty35 crw--w---- 1 root tty 4, 36 Sep 26 18:09 tty36 crw--w---- 1 root tty 4, 37 Sep 26 18:09 tty37 crw--w---- 1 root tty 4, 38 Sep 26 18:09 tty38 crw--w---- 1 root tty 4, 39 Sep 26 18:09 tty39 crw--w---- 1 root tty 4, 4 Sep 26 18:09 tty4 crw--w---- 1 root tty 4, 40 Sep 26 18:09 tty40 crw--w---- 1 root tty 4, 41 Sep 26 18:09 tty41 crw--w---- 1 root tty 4, 42 Sep 26 18:09 tty42 crw--w---- 1 root tty 4, 43 Sep 26 18:09 tty43 crw--w---- 1 root tty 4, 44 Sep 26 18:09 tty44 crw--w---- 1 root tty 4, 45 Sep 26 18:09 tty45 crw--w---- 1 root tty 4, 46 Sep 26 18:09 tty46 crw--w---- 1 root tty 4, 47 Sep 26 18:09 tty47 crw--w---- 1 root tty 4, 48 Sep 26 18:09 tty48 crw--w---- 1 root tty 4, 49 Sep 26 18:09 tty49 crw--w---- 1 root tty 4, 5 Sep 26 18:09 tty5 crw--w---- 1 root tty 4, 50 Sep 26 18:09 tty50 crw--w---- 1 root tty 4, 51 Sep 26 18:09 tty51 crw--w---- 1 root tty 4, 52 Sep 26 18:09 tty52 crw--w---- 1 root tty 4, 53 Sep 26 18:09 tty53 crw--w---- 1 root tty 4, 54 Sep 26 18:09 tty54 crw--w---- 1 root tty 4, 55 Sep 26 18:09 tty55 crw--w---- 1 root tty 4, 56 Sep 26 18:09 tty56 crw--w---- 1 root tty 4, 57 Sep 26 18:09 tty57 crw--w---- 1 root tty 4, 58 Sep 26 18:09 tty58 crw--w---- 1 root tty 4, 59 Sep 26 18:09 tty59 crw--w---- 1 root tty 4, 6 Sep 26 18:09 tty6 crw--w---- 1 root tty 4, 60 Sep 26 18:09 tty60 crw--w---- 1 root tty 4, 61 Sep 26 18:09 tty61 crw--w---- 1 root tty 4, 62 Sep 26 18:09 tty62 crw--w---- 1 root tty 4, 63 Sep 26 18:09 tty63 crw--w---- 1 root tty 4, 7 Sep 26 18:09 tty7 crw--w---- 1 root tty 4, 8 Sep 26 18:09 tty8 crw--w---- 1 root tty 4, 9 Sep 26 18:09 tty9 crw------- 1 root tty 4, 64 Sep 26 18:09 ttyS0 crw--w---- 1 root root 4, 65 Sep 26 18:09 ttyS1 crw-rw---- 1 root dialout 4, 66 Sep 26 18:09 ttyS2 crw-rw---- 1 root dialout 4, 67 Sep 26 18:09 ttyS3 crw------- 1 root root 10, 223 Sep 26 18:09 uinput crw-rw-rw- 1 root root 1, 9 Sep 26 18:09 urandom crw-rw---- 1 root tty 7, 0 Sep 26 18:09 vcs crw-rw---- 1 root tty 7, 1 Sep 26 18:09 vcs1 crw-rw---- 1 root tty 7, 128 Sep 26 18:09 vcsa crw-rw---- 1 root tty 7, 129 Sep 26 18:09 vcsa1 crw-rw---- 1 root tty 7, 64 Sep 26 18:09 vcsu crw-rw---- 1 root tty 7, 65 Sep 26 18:09 vcsu1 brw-rw---- 1 root disk 253, 0 Sep 26 18:09 vda crw------- 1 root root 10, 127 Sep 26 18:09 vga_arbiter crw-rw-rw- 1 root root 10, 126 Sep 26 18:09 vsock crw-rw-rw- 1 root root 1, 5 Sep 26 18:09 zero ----- In wrote a little script to check access to /dev entries for root, sudo and non sudo users and ran it on a systemd and sys-v image. Access permissions define who is allowed to access what and there are some files on sys-v where root has no write access. ===> /dev/fd -> /proc/self/fd ls /dev/fd 0 1 2 3 Access: (0500/dr-x------) Uid: ( 0/ root) Gid: ( 0/ root) : /proc/self/fd /proc/self/fd is readable for monitoring /proc/self/fd is readable for root /proc/self/fd is NOT writeable for monitoring ---> /proc/self/fd is NOT writeable for root <--- <=== ===> /dev/mtab -> /proc/mounts -> /proc/self/mounts cat /dev/mtab /dev/root / ext4 rw,relatime 0 0 devtmpfs /dev devtmpfs rw,relatime,size=109152k,nr_inodes=27288,mode=755 0 0 proc /proc proc rw,relatime 0 0 sysfs /sys sysfs rw,relatime 0 0 none /sys/kernel/debug debugfs rw,relatime 0 0 tmpfs /run tmpfs rw,nosuid,nodev,mode=755 0 0 tmpfs /var/volatile tmpfs rw,relatime 0 0 devpts /dev/pts devpts rw,relatime,gid=5,mode=620,ptmxmode=000 0 0 Access: (0777/lrwxrwxrwx) Uid: ( 0/ root) Gid: ( 0/ root) : /proc/mounts /proc/mounts is readable for monitoring /proc/mounts is readable for root /proc/mounts is NOT writeable for monitoring ---> /proc/mounts is NOT writeable for root <--- Access: (0444/-r--r--r--) Uid: ( 0/ root) Gid: ( 0/ root) : /proc/self/mounts /proc/self/mounts is readable for monitoring /proc/self/mounts is readable for root /proc/self/mounts is NOT writeable for monitoring ---> /proc/self/mounts is NOT writeable for root <--- <=== Now here comes the fun!!! systemd does not seem to create /dev/mtab and /dev/fd has different permissions: systemd: Access: (0777/lrwxrwxrwx) Uid: ( 0/ root) Gid: ( 0/ root) : /dev/fd /dev/fd is readable for monitoring /dev/fd is readable for nonroot /dev/fd is readable for root /dev/fd is writeable for monitoring /dev/fd is writeable for nonroot /dev/fd is writeable for root sys-v: Access: (0777/lrwxrwxrwx) Uid: ( 0/ root) Gid: ( 0/ root) : /dev/fd /dev/fd is readable for monitoring /dev/fd is readable for nonroot /dev/fd is readable for root /dev/fd is NOT writeable for monitoring /dev/fd is NOT writeable for nonroot ---> /dev/fd is NOT writeable for root <--- that's not permissions, since those seems to be the same, but the actual device ;) some permissions are slightly different: systemd: Access: (0777/lrwxrwxrwx) Uid: ( 0/ root) Gid: ( 0/ root) : /dev/initctl sys-v: Access: (0600/prw-------) Uid: ( 0/ root) Gid: ( 0/ root) : /dev/initctl with the same effect on reading/writing, but one is a symlink and the other a pipe systemd: Access: (0777/lrwxrwxrwx) Uid: ( 0/ root) Gid: ( 0/ root) : /dev/log sys-v: Access: (0666/srw-rw-rw-) Uid: ( 0/ root) Gid: ( 0/ root) : /dev/log the "setuid" bit, which might have security implications ;) systemd: Access: (0620/crw--w----) Uid: ( 0/ root) Gid: ( 5/ tty) : /dev/tty1 sys-v: Access: (0620/crw--w----) Uid: ( 0/ root) Gid: ( 0/ root) : /dev/tty1
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