These two manual pages both imply that a setuid process can call prctl(PR_SET_DUMPABLE, 1, 0, 0, 0); to set this flag back to 1 and restore the ownership of /proc files back to being the real user id of the process. This is not exactly true. Empirical testing reveals that this flag is ignored in favor of the value in /proc/sys/fs/suid_dumpable if either the real group or user id fail to match the effective group or user id. You can use prctl to set it to 1, and then prctl(PR_GET_DUMPABLE, 0, 0, 0, 0); to fetch it, and it will report as '1', but the ownership of files in /proc/self will remain as root:root until the effective and real ids match. This should be mentioned in the manual as it prescribes a very specific sequence of events that must happen to restore the ownership of these files that the current manual does not make clear. Thank you, -- Eric Hopper -- http://www.omnifarious.org/~hopper/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
