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authorRoland McGrath <roland@redhat.com>2007-11-11 19:13:43 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-11-12 10:32:29 -0800
commit00ec99da43a7c2aed46c6595aa271b84bb1b1462 (patch)
tree88eec24facdcba422db6a13206d4586daef9e1ad
parent6e800af233e0bdf108efb7bd23c11ea6fa34cdeb (diff)
core dump: remain dumpable
The coredump code always calls set_dumpable(0) when it starts (even if RLIMIT_CORE prevents any core from being dumped). The effect of this (via task_dumpable) is to make /proc/pid/* files owned by root instead of the user, so the user can no longer examine his own process--in a case where there was never any privileged data to protect. This affects e.g. auxv, environ, fd; in Fedora (execshield) kernels, also maps. In practice, you can only notice this when a debugger has requested PTRACE_EVENT_EXIT tracing. set_dumpable was only used in do_coredump for synchronization and not intended for any security purpose. (It doesn't secure anything that wasn't already unsecured when a process dies by SIGTERM instead of SIGQUIT.) This changes do_coredump to check the core_waiters count as the means of synchronization, which is sufficient. Now we leave the "dumpable" bits alone. Signed-off-by: Roland McGrath <roland@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/exec.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/fs/exec.c b/fs/exec.c
index 2c942e2d14ea..4ccaaa4b13b2 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1692,7 +1692,10 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs)
if (!binfmt || !binfmt->core_dump)
goto fail;
down_write(&mm->mmap_sem);
- if (!get_dumpable(mm)) {
+ /*
+ * If another thread got here first, or we are not dumpable, bail out.
+ */
+ if (mm->core_waiters || !get_dumpable(mm)) {
up_write(&mm->mmap_sem);
goto fail;
}
@@ -1706,7 +1709,6 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs)
flag = O_EXCL; /* Stop rewrite attacks */
current->fsuid = 0; /* Dump root private */
}
- set_dumpable(mm, 0);
retval = coredump_wait(exit_code);
if (retval < 0)