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| author | Rui Salvaterra <rsalvaterra@gmail.com> | 2022-01-09 23:27:27 +0000 |
|---|---|---|
| committer | Daniel Golle <daniel@makrotopia.org> | 2022-01-11 16:23:05 +0000 |
| commit | 3b3ac648f48dda5269852994d42c70f61e9db4fe (patch) | |
| tree | 08d549fdc2418e5241621d72a4d602b4ccbab9a9 | |
| parent | 35dfbffc2d2e3772332e965342778259c79581ab (diff) | |
| download | procd-3b3ac648f48dda5269852994d42c70f61e9db4fe.tar.gz | |
procd: mount /dev with noexec
/dev is writable. Allowing execution inside it makes it a possible attack
vector. Kees Cook recently sent a kernel patch [1] in order to mount /dev as
noexec and nosuid for systems which rely on CONFIG_DEVTMPFS_MOUNT=y to
create/populate /dev, which isn't our case (it's procd's responsibility).
Add noexec to the /dev mount flags, since we already use nosuid (and keep the
coldplug flags symmetric, while at it). This carries the risk of breaking very
old, pre-KMS graphics drivers [2], but it shouldn't be a problem for systems
built in the last ~15 years. The vast majority of our targets doesn't have a
GPU, anyway. :)
[1] https://lore.kernel.org/all/YcMfDOyrg647RCmd@debian-BULLSEYE-live-builder-AMD64/
[2] https://lore.kernel.org/all/CAPXgP12e5LpN6XVxaXOHhH=u8XXN==2reTaJDCoCk4tP4QduDQ@mail.gmail.com/
Signed-off-by: Rui Salvaterra <rsalvaterra@gmail.com>
| -rw-r--r-- | initd/early.c | 2 | ||||
| -rw-r--r-- | plug/coldplug.c | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/initd/early.c b/initd/early.c index d69495e..87fee65 100644 --- a/initd/early.c +++ b/initd/early.c @@ -61,7 +61,7 @@ early_mounts(void) mount("proc", "/proc", "proc", MS_NOATIME | MS_NODEV | MS_NOEXEC | MS_NOSUID, 0); mount("sysfs", "/sys", "sysfs", MS_NOATIME | MS_NODEV | MS_NOEXEC | MS_NOSUID, 0); mount("cgroup2", "/sys/fs/cgroup", "cgroup2", MS_NODEV | MS_NOEXEC | MS_NOSUID | MS_RELATIME, "nsdelegate"); - mount("tmpfs", "/dev", "tmpfs", MS_NOATIME | MS_NOSUID, "mode=0755,size=512K"); + mount("tmpfs", "/dev", "tmpfs", MS_NOATIME | MS_NOEXEC | MS_NOSUID, "mode=0755,size=512K"); ignore(symlink("/tmp/shm", "/dev/shm")); mkdir("/dev/pts", 0755); mount("devpts", "/dev/pts", "devpts", MS_NOATIME | MS_NOEXEC | MS_NOSUID, "mode=600"); diff --git a/plug/coldplug.c b/plug/coldplug.c index b185083..b9462e7 100644 --- a/plug/coldplug.c +++ b/plug/coldplug.c @@ -48,7 +48,7 @@ void procd_coldplug(void) if (!is_container()) { umount2("/dev/pts", MNT_DETACH); umount2("/dev/", MNT_DETACH); - mount("tmpfs", "/dev", "tmpfs", MS_NOSUID, "mode=0755,size=512K"); + mount("tmpfs", "/dev", "tmpfs", MS_NOATIME | MS_NOEXEC | MS_NOSUID, "mode=0755,size=512K"); mkdir("/dev/pts", 0755); mount("devpts", "/dev/pts", "devpts", MS_NOEXEC | MS_NOSUID, 0); } |