Closing the MAAS task as it the referenced bug is marked Fix Release. If there are issues there still, please see my previous comment and look at the code in that snap-- there are viable ways to use overlayfs with chroot and an apparmor alias rule, or overlayfs with private mount, chroot and pivot_root.
** Changed in: maas Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to apparmor in Ubuntu. https://bugs.launchpad.net/bugs/1408106 Title: attach_disconnected not sufficient for overlayfs Status in AppArmor: Invalid Status in MAAS: Incomplete Status in apparmor package in Ubuntu: Invalid Status in linux package in Ubuntu: Invalid Bug description: With the following use of overlayfs, we get a disconnected path: $ cat ./profile #include <tunables/global> profile foo { #include <abstractions/base> capability sys_admin, capability sys_chroot, mount, pivot_root, } $ cat ./overlay.c #include <alloca.h> #include <linux/sched.h> #include <stdio.h> #include <string.h> #include <sys/mount.h> #include <fcntl.h> #include <unistd.h> int main(int argc, char* argv[]) { int i = 0; int len = 0; int ret = 0; char* options; if (geteuid()) unshare(CLONE_NEWUSER); unshare(CLONE_NEWNS); for (i = 1; i < argc; i++) { if (i == 1) { len = strlen(argv[i]) + strlen("upperdir=,lowerdir=/") + 2; options = alloca(len); ret = snprintf(options, len, "upperdir=%s,lowerdir=/", argv[i]); } else { len = strlen(argv[i]) + strlen("upperdir=,lowerdir=/mnt") + 2; options = alloca(len); ret = snprintf(options, len, "upperdir=%s,lowerdir=/mnt", argv[i]); } mount("overlayfs", "/mnt", "overlayfs", MS_MGC_VAL, options); } chdir("/mnt"); pivot_root(".", "."); chroot("."); chdir("/"); execl("/bin/bash", "/bin/bash", NULL); } $ sudo apparmor_parser -r ./profile && aa-exec -p foo -- ./a.out /tmp [255] ... Dec 12 14:31:38 localhost kernel: [57278.040216] audit: type=1400 audit(1418387498.613:712): apparmor="DENIED" operation="exec" info="Failed name lookup - disconnected path" error=-13 profile="foo" name="/bin/bash" pid=18255 comm="a.out" requested_mask="x" denied_mask="x" fsuid=1000 ouid=0 With the above, the expectation was for the denial to be /mnt/bin/bash. There are three ways forward: 1. the correct solution is to patch overlayfs to properly track the loopback, but this will take a while, may ultimately be unachievable. UPDATE: upstream is currently working on this and Ubuntu will engage with them 2. we could rely on the fact that overlayfs creates a private unshared submount, and provide a way to not mediate the path when that is present, and tagged. This would take a bit of time, and might be the preferred method over 1 longer term 3. we could extend attach_disconnected so that we can define the attach root. Eg, we can use profile foo (attach_disconnected=/mnt) {} such that '/bin/bash' maps to '/mnt/bin/bash'. UPDATE: THIS IS NOT VIABLE To manage notifications about this bug go to: https://bugs.launchpad.net/apparmor/+bug/1408106/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp