67 lines
2.0 KiB
Diff
67 lines
2.0 KiB
Diff
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From 60aa0fa94c00942cc2c9f67f05d4a0d9e15349c7 Mon Sep 17 00:00:00 2001
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From: Oleg Nesterov <oleg@redhat.com>
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Date: Thu, 3 Sep 2009 19:21:45 +0200
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Subject: [PATCH] sys_setrlimit: make sure ->rlim_max never grows
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References: FATE#305733
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Patch-mainline: no (later)
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Mostly preparation for Jiri's changes, but probably makes sense anyway.
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sys_setrlimit() checks new_rlim.rlim_max <= old_rlim->rlim_max, but when
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it takes task_lock() old_rlim->rlim_max can be already lowered. Move this
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check under task_lock().
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Currently this is not important, we can only race with our sub-thread,
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this means the application is stupid. But when we change the code to allow
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the update of !current task's limits, it becomes important to make sure
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->rlim_max can be lowered "reliably" even if we race with the application
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doing sys_setrlimit().
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Signed-off-by: Oleg Nesterov <oleg@redhat.com>
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Signed-off-by: Jiri Slaby <jslaby@suse.cz>
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---
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kernel/sys.c | 15 ++++++++-------
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1 file changed, 8 insertions(+), 7 deletions(-)
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--- a/kernel/sys.c
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+++ b/kernel/sys.c
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@@ -1313,10 +1313,6 @@ SYSCALL_DEFINE2(setrlimit, unsigned int,
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return -EFAULT;
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if (new_rlim.rlim_cur > new_rlim.rlim_max)
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return -EINVAL;
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- old_rlim = current->signal->rlim + resource;
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- if ((new_rlim.rlim_max > old_rlim->rlim_max) &&
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- !capable(CAP_SYS_RESOURCE))
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- return -EPERM;
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if (resource == RLIMIT_NOFILE && new_rlim.rlim_max > sysctl_nr_open)
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return -EPERM;
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@@ -1334,11 +1330,16 @@ SYSCALL_DEFINE2(setrlimit, unsigned int,
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new_rlim.rlim_cur = 1;
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}
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+ old_rlim = current->signal->rlim + resource;
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task_lock(current->group_leader);
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- *old_rlim = new_rlim;
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+ if ((new_rlim.rlim_max <= old_rlim->rlim_max) ||
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+ capable(CAP_SYS_RESOURCE))
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+ *old_rlim = new_rlim;
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+ else
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+ retval = -EPERM;
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task_unlock(current->group_leader);
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- if (resource != RLIMIT_CPU)
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+ if (retval || resource != RLIMIT_CPU)
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goto out;
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/*
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@@ -1352,7 +1353,7 @@ SYSCALL_DEFINE2(setrlimit, unsigned int,
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update_rlimit_cpu(current, new_rlim.rlim_cur);
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out:
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- return 0;
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+ return retval;
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}
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/*
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