Messages in this thread Patch in this message | | | Date | Sun, 13 Sep 2015 00:56:38 +0200 | From | Willy Tarreau <> | Subject | [PATCH 2.6.32 32/62] __ptrace_may_access() should not deny sub-threads |
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2.6.32-longterm review patch. If anyone has any objections, please let me know.
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From: Mark Grondona <mgrondona@llnl.gov>
commit 73af963f9f3036dffed55c3a2898598186db1045 upstream.
__ptrace_may_access() checks get_dumpable/ptrace_has_cap/etc if task != current, this can can lead to surprising results.
For example, a sub-thread can't readlink("/proc/self/exe") if the executable is not readable. setup_new_exec()->would_dump() notices that inode_permission(MAY_READ) fails and then it does set_dumpable(suid_dumpable). After that get_dumpable() fails.
(It is not clear why proc_pid_readlink() checks get_dumpable(), perhaps we could add PTRACE_MODE_NODUMPABLE)
Change __ptrace_may_access() to use same_thread_group() instead of "task == current". Any security check is pointless when the tasks share the same ->mm.
Signed-off-by: Mark Grondona <mgrondona@llnl.gov> Signed-off-by: Ben Woodard <woodard@redhat.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Cc: Sheng Yong <shengyong1@huawei.com> (cherry picked from commit f062bd6e420a064a19563b80c26d746b0262e404)
Signed-off-by: Willy Tarreau <w@1wt.eu> --- kernel/ptrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 03da336..426b0c8 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -169,7 +169,7 @@ int __ptrace_may_access(struct task_struct *task, unsigned int mode) */ int dumpable = 0; /* Don't let security modules deny introspection */ - if (task == current) + if (same_thread_group(task, current)) return 0; rcu_read_lock(); tcred = __task_cred(task); -- 1.7.12.2.21.g234cd45.dirty
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