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| author | Mark Grondona <mgrondona@llnl.gov> | 2013-09-11 14:24:31 -0700 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2015-08-07 00:32:18 +0100 |
| commit | f062bd6e420a064a19563b80c26d746b0262e404 (patch) | |
| tree | ae9c4a8e9ff5a2757b080cba8c513b320a77bda4 | |
| parent | a7b4d51399316329b6a3d9eaeab224d83eeebe67 (diff) | |
| download | lwn-f062bd6e420a064a19563b80c26d746b0262e404.tar.gz lwn-f062bd6e420a064a19563b80c26d746b0262e404.zip | |
__ptrace_may_access() should not deny sub-threads
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>
| -rw-r--r-- | kernel/ptrace.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 464b1fe45a30..f07c1441675c 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -225,7 +225,7 @@ 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); |