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pidns: fix set/getpriority and ioprio_set/get in PRIO_USER mode

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setpriority(PRIO_USER, 0, x) will change the priority of tasks outside of
the current pid namespace.  This is in contrast to both the other modes of
setpriority and the example of kill(-1).  Fix this.  getpriority and
ioprio have the same failure mode, fix them too.

Eric said:

: After some more thinking about it this patch sounds justifiable.
:
: My goal with namespaces is not to build perfect isolation mechanisms
: as that can get into ill defined territory, but to build well defined
: mechanisms.  And to handle the corner cases so you can use only
: a single namespace with well defined results.
:
: In this case you have found the two interfaces I am aware of that
: identify processes by uid instead of by pid.  Which quite frankly is
: weird.  Unfortunately the weird unexpected cases are hard to handle
: in the usual way.
:
: I was hoping for a little more information.  Changes like this one we
: have to be careful of because someone might be depending on the current
: behavior.  I don't think they are and I do think this make sense as part
: of the pid namespace.

Signed-off-by: Ben Segall <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Ambrose Feinstein <[email protected]>
Acked-by: "Eric W. Biederman" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Ben Segall authored and Linus Torvalds committed 2015-11-06 17:50:42 -08:00
1 parent de90a6bcae
commit 8639b46139
2 files changed
+6 -4
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block/ioprio.c
+4 -2
View File
@@ -123,7 +123,8 @@ SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio)
break;
do_each_thread(g, p) {
if (!uid_eq(task_uid(p), uid))
if (!uid_eq(task_uid(p), uid) ||
!task_pid_vnr(p))
continue;
ret = set_task_ioprio(p, ioprio);
if (ret)
@@ -220,7 +221,8 @@ SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
break;
do_each_thread(g, p) {
if (!uid_eq(task_uid(p), user->uid))
if (!uid_eq(task_uid(p), user->uid) ||
!task_pid_vnr(p))
continue;
tmpio = get_task_ioprio(p);
if (tmpio < 0)
kernel/sys.c
+2 -2
View File
@@ -222,7 +222,7 @@ SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval)
goto out_unlock; /* No processes for this user */
}
do_each_thread(g, p) {
if (uid_eq(task_uid(p), uid))
if (uid_eq(task_uid(p), uid) && task_pid_vnr(p))
error = set_one_prio(p, niceval, error);
} while_each_thread(g, p);
if (!uid_eq(uid, cred->uid))
@@ -290,7 +290,7 @@ SYSCALL_DEFINE2(getpriority, int, which, int, who)
goto out_unlock; /* No processes for this user */
}
do_each_thread(g, p) {
if (uid_eq(task_uid(p), uid)) {
if (uid_eq(task_uid(p), uid) && task_pid_vnr(p)) {
niceval = nice_to_rlimit(task_nice(p));
if (niceval > retval)
retval = niceval;