From 97829955ad291acec1d8b94e9911b3ceb1118bb1 Mon Sep 17 00:00:00 2001 From: "Serge E. Hallyn" Date: Mon, 4 Feb 2008 22:29:47 -0800 Subject: [PATCH] oom_kill: remove uid==0 checks Root processes are considered more important when out of memory and killing proceses. The check for CAP_SYS_ADMIN was augmented with a check for uid==0 or euid==0. There are several possible ways to look at this: 1. uid comparisons are unnecessary, trust CAP_SYS_ADMIN alone. However CAP_SYS_RESOURCE is the one that really means "give me extra resources" so allow for that as well. 2. Any privileged code should be protected, but uid is not an indication of privilege. So we should check whether any capabilities are raised. 3. uid==0 makes processes on the host as well as in containers more important, so we should keep the existing checks. 4. uid==0 makes processes only on the host more important, even without any capabilities. So we should be keeping the (uid==0||euid==0) check but only when userns==&init_user_ns. I'm following number 1 here. Signed-off-by: Serge Hallyn Cc: Andrew Morgan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/oom_kill.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 320d74e707af..c1850bf991cd 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -125,7 +125,7 @@ unsigned long badness(struct task_struct *p, unsigned long uptime) * Superuser processes are usually more important, so we make it * less likely that we kill those. */ - if (__capable(p, CAP_SYS_ADMIN) || p->uid == 0 || p->euid == 0) + if (__capable(p, CAP_SYS_ADMIN) || __capable(p, CAP_SYS_RESOURCE)) points /= 4; /* -- 2.20.1