classes/sanity: check for suid root command evility

Some users have been found to have an unnamed third-party piece of software installed which sets chmod, chown and mknod as suid root as part of its installation process. This interferes with the operation of pseudo and can result in files really being owned by root within the build output, and therefore breaks the build, apart from being a security issue. Check for this and bail out early if it is found.

Reported-by Nicolas Dechesne <[email protected]>

Signed-off-by Paul Eggleton <[email protected]>

---
  meta/classes/sanity.bbclass | 10 ++++++++++
  1 file changed, 10 insertions(+)

meta/classes/sanity.bbclass +10 -0

index a505a5d..0546293 100644
@@ -569,6 +569,16 @@ def check_sanity_everybuild(status, d):
      if 0 == os.getuid():
          raise_sanity_error("Do not use Bitbake as root.", d)
 
+    # Some third-party software apparently relies on chmod etc. being suid root (!!)
+    import stat
+    suid_check_bins = "chown chmod mknod".split()
+    for bin_cmd in suid_check_bins:
+        bin_path = bb.utils.which(os.environ["PATH"], bin_cmd)
+        if bin_path:
+            bin_stat = os.stat(bin_path)
+            if bin_stat.st_uid == 0 and bin_stat.st_mode & stat.S_ISUID:
+                status.addresult('%s has the setuid bit set. This interferes with pseudo and may cause other issues that break the build process.\n' % bin_path)
+
      # Check the Python version, we now have a minimum of Python 2.7.3
      import sys
      if sys.hexversion < 0x020703F0:

Quoted 7 lines · Paul Eggleton

Some users have been found to have an unnamed third-party piece of software installed which sets chmod, chown and mknod as suid root as part of its installation process. This interferes with the operation of pseudo and can result in files really being owned by root within the build output, and therefore breaks the build, apart from being a security issue. Check for this and bail out early if it is found.

Quoted 3 lines

Reported-by Nicolas Dechesne <[email protected]>

Signed-off-by Paul Eggleton <[email protected]>

Should these items be added to the buildtools-tarball target? It might help avoid the problem in the same way we already do to detect the bad make, tar, etc..