Subject: + fork-reorder-permissions-when-violating-number-of-processes-limits.patch added to -mm tree
To: eparis@xxxxxxxxxx,viro@xxxxxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 14 May 2013 12:36:09 -0700
The patch titled
Subject: fork: reorder permissions when violating number of processes limits
has been added to the -mm tree. Its filename is
fork-reorder-permissions-when-violating-number-of-processes-limits.patch
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From: Eric Paris <eparis@xxxxxxxxxx>
Subject: fork: reorder permissions when violating number of processes limits
When a task is attempting to violate the RLIMIT_NPROC limit we have a
check to see if the task is sufficiently priviledged. The check first
looks at CAP_SYS_ADMIN, then CAP_SYS_RESOURCE, then if the task is uid=0.
A result is that tasks which are allowed by the uid=0 check are first
checked against the security subsystem. This results in the security
subsystem auditting a denial for sys_admin and sys_resource and then the
task passing the uid=0 check.
This patch rearranges the code to first check uid=0, since if we pass that
we shouldn't hit the security system at all. We then check sys_resource,
since it is the smallest capability which will solve the problem. Lastly
we check the fallback everything cap_sysadmin. We don't want to give this
capability many places since it is so powerful.
This will eliminate many of the false positive/needless denial messages we
get when a root task tries to violate the nproc limit. (note that
kthreads count against root, so on a sufficiently large machine we can
actually get past the default limits before any userspace tasks are
launched.)
Signed-off-by: Eric Paris <eparis@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/fork.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff -puN kernel/fork.c~fork-reorder-permissions-when-violating-number-of-processes-limits kernel/fork.c
--- a/kernel/fork.c~fork-reorder-permissions-when-violating-number-of-processes-limits
+++ a/kernel/fork.c
@@ -1195,8 +1195,8 @@ static struct task_struct *copy_process(
retval = -EAGAIN;
if (atomic_read(&p->real_cred->user->processes) >=
task_rlimit(p, RLIMIT_NPROC)) {
- if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
- p->real_cred->user != INIT_USER)
+ if (p->real_cred->user != INIT_USER &&
+ !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
goto bad_fork_free;
}
current->flags &= ~PF_NPROC_EXCEEDED;
_
Patches currently in -mm which might be from eparis@xxxxxxxxxx are
kernel-audit_treec-audit_add_tree_rule-protect-rule-from-kill_rules.patch
audit-fix-mq_open-and-mq_unlink-to-add-the-mq-root-as-a-hidden-parent-audit_names-record.patch
fork-reorder-permissions-when-violating-number-of-processes-limits.patch
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