License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 14:07:57 +00:00
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// SPDX-License-Identifier: GPL-2.0
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2012-09-27 01:52:08 +00:00
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#include <linux/slab.h>
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#include <linux/file.h>
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#include <linux/fdtable.h>
|
2016-11-10 18:46:38 +00:00
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#include <linux/freezer.h>
|
2012-09-27 01:52:08 +00:00
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|
#include <linux/mm.h>
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#include <linux/stat.h>
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#include <linux/fcntl.h>
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#include <linux/swap.h>
|
2019-08-03 04:49:05 +00:00
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#include <linux/ctype.h>
|
2012-09-27 01:52:08 +00:00
|
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#include <linux/string.h>
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#include <linux/init.h>
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#include <linux/pagemap.h>
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#include <linux/perf_event.h>
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#include <linux/highmem.h>
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#include <linux/spinlock.h>
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#include <linux/key.h>
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#include <linux/personality.h>
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#include <linux/binfmts.h>
|
2012-10-05 00:15:24 +00:00
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#include <linux/coredump.h>
|
2017-02-08 17:51:30 +00:00
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#include <linux/sched/coredump.h>
|
2017-02-08 17:51:30 +00:00
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#include <linux/sched/signal.h>
|
2017-02-08 17:51:37 +00:00
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|
#include <linux/sched/task_stack.h>
|
2012-09-27 01:52:08 +00:00
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#include <linux/utsname.h>
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#include <linux/pid_namespace.h>
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#include <linux/module.h>
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#include <linux/namei.h>
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#include <linux/mount.h>
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#include <linux/security.h>
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#include <linux/syscalls.h>
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#include <linux/tsacct_kern.h>
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#include <linux/cn_proc.h>
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#include <linux/audit.h>
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#include <linux/tracehook.h>
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#include <linux/kmod.h>
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#include <linux/fsnotify.h>
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#include <linux/fs_struct.h>
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#include <linux/pipe_fs_i.h>
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#include <linux/oom.h>
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#include <linux/compat.h>
|
2016-03-22 21:25:36 +00:00
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#include <linux/fs.h>
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#include <linux/path.h>
|
2015-11-25 15:22:25 +00:00
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#include <linux/timekeeping.h>
|
2012-09-27 01:52:08 +00:00
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|
2016-12-24 19:46:01 +00:00
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#include <linux/uaccess.h>
|
2012-09-27 01:52:08 +00:00
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#include <asm/mmu_context.h>
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#include <asm/tlb.h>
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#include <asm/exec.h>
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#include <trace/events/task.h>
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#include "internal.h"
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#include <trace/events/sched.h>
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int core_uses_pid;
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|
unsigned int core_pipe_limit;
|
2013-07-03 22:08:22 +00:00
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char core_pattern[CORENAME_MAX_SIZE] = "core";
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static int core_name_size = CORENAME_MAX_SIZE;
|
2012-09-27 01:52:08 +00:00
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struct core_name {
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|
char *corename;
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int used, size;
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};
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/* The maximal length of core_pattern is also specified in sysctl.c */
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|
2013-07-03 22:08:22 +00:00
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static int expand_corename(struct core_name *cn, int size)
|
2012-09-27 01:52:08 +00:00
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|
{
|
2013-07-03 22:08:16 +00:00
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char *corename = krealloc(cn->corename, size, GFP_KERNEL);
|
2012-09-27 01:52:08 +00:00
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|
2013-07-03 22:08:16 +00:00
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if (!corename)
|
2012-09-27 01:52:08 +00:00
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return -ENOMEM;
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2013-07-03 22:08:22 +00:00
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if (size > core_name_size) /* racy but harmless */
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core_name_size = size;
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cn->size = ksize(corename);
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2013-07-03 22:08:16 +00:00
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cn->corename = corename;
|
2012-09-27 01:52:08 +00:00
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return 0;
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}
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|
2015-06-25 22:03:53 +00:00
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static __printf(2, 0) int cn_vprintf(struct core_name *cn, const char *fmt,
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va_list arg)
|
2012-09-27 01:52:08 +00:00
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{
|
2013-07-03 22:08:19 +00:00
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int free, need;
|
2014-04-19 17:15:07 +00:00
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va_list arg_copy;
|
2012-09-27 01:52:08 +00:00
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|
2013-07-03 22:08:19 +00:00
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again:
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free = cn->size - cn->used;
|
2014-04-19 17:15:07 +00:00
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va_copy(arg_copy, arg);
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need = vsnprintf(cn->corename + cn->used, free, fmt, arg_copy);
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va_end(arg_copy);
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2013-07-03 22:08:19 +00:00
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if (need < free) {
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cn->used += need;
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return 0;
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}
|
2012-09-27 01:52:08 +00:00
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2013-07-03 22:08:22 +00:00
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if (!expand_corename(cn, cn->size + need - free + 1))
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2013-07-03 22:08:19 +00:00
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goto again;
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2012-09-27 01:52:08 +00:00
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2013-07-03 22:08:19 +00:00
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return -ENOMEM;
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2012-09-27 01:52:08 +00:00
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}
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2015-06-25 22:03:53 +00:00
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static __printf(2, 3) int cn_printf(struct core_name *cn, const char *fmt, ...)
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2013-07-03 22:08:17 +00:00
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{
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va_list arg;
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int ret;
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va_start(arg, fmt);
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ret = cn_vprintf(cn, fmt, arg);
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va_end(arg);
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return ret;
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}
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|
2015-06-25 22:03:53 +00:00
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static __printf(2, 3)
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int cn_esc_printf(struct core_name *cn, const char *fmt, ...)
|
2012-09-27 01:52:08 +00:00
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{
|
2013-07-03 22:08:20 +00:00
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int cur = cn->used;
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va_list arg;
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int ret;
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va_start(arg, fmt);
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ret = cn_vprintf(cn, fmt, arg);
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va_end(arg);
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|
2016-01-20 23:00:08 +00:00
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if (ret == 0) {
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/*
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|
* Ensure that this coredump name component can't cause the
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* resulting corefile path to consist of a ".." or ".".
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*/
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if ((cn->used - cur == 1 && cn->corename[cur] == '.') ||
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(cn->used - cur == 2 && cn->corename[cur] == '.'
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&& cn->corename[cur+1] == '.'))
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cn->corename[cur] = '!';
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/*
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|
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* Empty names are fishy and could be used to create a "//" in a
|
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* corefile name, causing the coredump to happen one directory
|
|
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* level too high. Enforce that all components of the core
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* pattern are at least one character long.
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*/
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if (cn->used == cur)
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ret = cn_printf(cn, "!");
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}
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|
2013-07-03 22:08:20 +00:00
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for (; cur < cn->used; ++cur) {
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if (cn->corename[cur] == '/')
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cn->corename[cur] = '!';
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}
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return ret;
|
2012-09-27 01:52:08 +00:00
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}
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|
2020-08-12 01:36:20 +00:00
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static int cn_print_exe_file(struct core_name *cn, bool name_only)
|
2012-09-27 01:52:08 +00:00
|
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|
{
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struct file *exe_file;
|
2020-08-12 01:36:20 +00:00
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char *pathbuf, *path, *ptr;
|
2012-09-27 01:52:08 +00:00
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int ret;
|
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|
exe_file = get_mm_exe_file(current->mm);
|
2013-07-03 22:08:20 +00:00
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|
if (!exe_file)
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|
return cn_esc_printf(cn, "%s (path unknown)", current->comm);
|
2012-09-27 01:52:08 +00:00
|
|
|
|
2017-09-13 23:28:29 +00:00
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|
pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
|
2012-09-27 01:52:08 +00:00
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|
if (!pathbuf) {
|
|
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|
ret = -ENOMEM;
|
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|
goto put_exe_file;
|
|
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|
}
|
|
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|
|
2015-06-19 08:29:13 +00:00
|
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|
path = file_path(exe_file, pathbuf, PATH_MAX);
|
2012-09-27 01:52:08 +00:00
|
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|
if (IS_ERR(path)) {
|
|
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|
ret = PTR_ERR(path);
|
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|
goto free_buf;
|
|
|
|
}
|
|
|
|
|
2020-08-12 01:36:20 +00:00
|
|
|
if (name_only) {
|
|
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ptr = strrchr(path, '/');
|
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if (ptr)
|
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path = ptr + 1;
|
|
|
|
}
|
2013-07-03 22:08:20 +00:00
|
|
|
ret = cn_esc_printf(cn, "%s", path);
|
2012-09-27 01:52:08 +00:00
|
|
|
|
|
|
|
free_buf:
|
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|
kfree(pathbuf);
|
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put_exe_file:
|
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|
fput(exe_file);
|
|
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|
return ret;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* format_corename will inspect the pattern parameter, and output a
|
|
|
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* name into corename, which must have space for at least
|
|
|
|
* CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
|
|
|
|
*/
|
2019-08-03 04:49:05 +00:00
|
|
|
static int format_corename(struct core_name *cn, struct coredump_params *cprm,
|
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|
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size_t **argv, int *argc)
|
2012-09-27 01:52:08 +00:00
|
|
|
{
|
|
|
|
const struct cred *cred = current_cred();
|
|
|
|
const char *pat_ptr = core_pattern;
|
|
|
|
int ispipe = (*pat_ptr == '|');
|
2019-08-03 04:49:05 +00:00
|
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|
bool was_space = false;
|
2012-09-27 01:52:08 +00:00
|
|
|
int pid_in_pattern = 0;
|
|
|
|
int err = 0;
|
|
|
|
|
2013-07-03 22:08:16 +00:00
|
|
|
cn->used = 0;
|
2013-07-03 22:08:22 +00:00
|
|
|
cn->corename = NULL;
|
|
|
|
if (expand_corename(cn, core_name_size))
|
2012-09-27 01:52:08 +00:00
|
|
|
return -ENOMEM;
|
2013-07-03 22:08:23 +00:00
|
|
|
cn->corename[0] = '\0';
|
|
|
|
|
2019-08-03 04:49:05 +00:00
|
|
|
if (ispipe) {
|
|
|
|
int argvs = sizeof(core_pattern) / 2;
|
|
|
|
(*argv) = kmalloc_array(argvs, sizeof(**argv), GFP_KERNEL);
|
|
|
|
if (!(*argv))
|
|
|
|
return -ENOMEM;
|
|
|
|
(*argv)[(*argc)++] = 0;
|
2013-07-03 22:08:23 +00:00
|
|
|
++pat_ptr;
|
2020-04-21 01:14:20 +00:00
|
|
|
if (!(*pat_ptr))
|
|
|
|
return -ENOMEM;
|
2019-08-03 04:49:05 +00:00
|
|
|
}
|
2012-09-27 01:52:08 +00:00
|
|
|
|
|
|
|
/* Repeat as long as we have more pattern to process and more output
|
|
|
|
space */
|
|
|
|
while (*pat_ptr) {
|
2019-08-03 04:49:05 +00:00
|
|
|
/*
|
|
|
|
* Split on spaces before doing template expansion so that
|
|
|
|
* %e and %E don't get split if they have spaces in them
|
|
|
|
*/
|
|
|
|
if (ispipe) {
|
|
|
|
if (isspace(*pat_ptr)) {
|
2020-12-06 06:14:42 +00:00
|
|
|
if (cn->used != 0)
|
|
|
|
was_space = true;
|
2019-08-03 04:49:05 +00:00
|
|
|
pat_ptr++;
|
|
|
|
continue;
|
|
|
|
} else if (was_space) {
|
|
|
|
was_space = false;
|
|
|
|
err = cn_printf(cn, "%c", '\0');
|
|
|
|
if (err)
|
|
|
|
return err;
|
|
|
|
(*argv)[(*argc)++] = cn->used;
|
|
|
|
}
|
|
|
|
}
|
2012-09-27 01:52:08 +00:00
|
|
|
if (*pat_ptr != '%') {
|
|
|
|
err = cn_printf(cn, "%c", *pat_ptr++);
|
|
|
|
} else {
|
|
|
|
switch (*++pat_ptr) {
|
|
|
|
/* single % at the end, drop that */
|
|
|
|
case 0:
|
|
|
|
goto out;
|
|
|
|
/* Double percent, output one percent */
|
|
|
|
case '%':
|
|
|
|
err = cn_printf(cn, "%c", '%');
|
|
|
|
break;
|
|
|
|
/* pid */
|
|
|
|
case 'p':
|
|
|
|
pid_in_pattern = 1;
|
|
|
|
err = cn_printf(cn, "%d",
|
|
|
|
task_tgid_vnr(current));
|
|
|
|
break;
|
2013-09-11 21:24:32 +00:00
|
|
|
/* global pid */
|
|
|
|
case 'P':
|
|
|
|
err = cn_printf(cn, "%d",
|
|
|
|
task_tgid_nr(current));
|
|
|
|
break;
|
2014-10-13 22:53:35 +00:00
|
|
|
case 'i':
|
|
|
|
err = cn_printf(cn, "%d",
|
|
|
|
task_pid_vnr(current));
|
|
|
|
break;
|
|
|
|
case 'I':
|
|
|
|
err = cn_printf(cn, "%d",
|
|
|
|
task_pid_nr(current));
|
|
|
|
break;
|
2012-09-27 01:52:08 +00:00
|
|
|
/* uid */
|
|
|
|
case 'u':
|
coredump: use from_kuid/kgid when formatting corename
When adding __printf attribute to cn_printf, gcc reports some issues:
fs/coredump.c:213:5: warning: format '%d' expects argument of type
'int', but argument 3 has type 'kuid_t' [-Wformat=]
err = cn_printf(cn, "%d", cred->uid);
^
fs/coredump.c:217:5: warning: format '%d' expects argument of type
'int', but argument 3 has type 'kgid_t' [-Wformat=]
err = cn_printf(cn, "%d", cred->gid);
^
These warnings come from the fact that the value of uid/gid needs to be
extracted from the kuid_t/kgid_t structure before being used as an
integer. More precisely, cred->uid and cred->gid need to be converted to
either user-namespace uid/gid or to init_user_ns uid/gid.
Use init_user_ns in order not to break existing ABI, and document this in
Documentation/sysctl/kernel.txt.
While at it, format uid and gid values with %u instead of %d because
uid_t/__kernel_uid32_t and gid_t/__kernel_gid32_t are unsigned int.
Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-25 22:03:51 +00:00
|
|
|
err = cn_printf(cn, "%u",
|
|
|
|
from_kuid(&init_user_ns,
|
|
|
|
cred->uid));
|
2012-09-27 01:52:08 +00:00
|
|
|
break;
|
|
|
|
/* gid */
|
|
|
|
case 'g':
|
coredump: use from_kuid/kgid when formatting corename
When adding __printf attribute to cn_printf, gcc reports some issues:
fs/coredump.c:213:5: warning: format '%d' expects argument of type
'int', but argument 3 has type 'kuid_t' [-Wformat=]
err = cn_printf(cn, "%d", cred->uid);
^
fs/coredump.c:217:5: warning: format '%d' expects argument of type
'int', but argument 3 has type 'kgid_t' [-Wformat=]
err = cn_printf(cn, "%d", cred->gid);
^
These warnings come from the fact that the value of uid/gid needs to be
extracted from the kuid_t/kgid_t structure before being used as an
integer. More precisely, cred->uid and cred->gid need to be converted to
either user-namespace uid/gid or to init_user_ns uid/gid.
Use init_user_ns in order not to break existing ABI, and document this in
Documentation/sysctl/kernel.txt.
While at it, format uid and gid values with %u instead of %d because
uid_t/__kernel_uid32_t and gid_t/__kernel_gid32_t are unsigned int.
Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-25 22:03:51 +00:00
|
|
|
err = cn_printf(cn, "%u",
|
|
|
|
from_kgid(&init_user_ns,
|
|
|
|
cred->gid));
|
2012-09-27 01:52:08 +00:00
|
|
|
break;
|
2012-10-05 00:15:25 +00:00
|
|
|
case 'd':
|
|
|
|
err = cn_printf(cn, "%d",
|
|
|
|
__get_dumpable(cprm->mm_flags));
|
|
|
|
break;
|
2012-09-27 01:52:08 +00:00
|
|
|
/* signal that caused the coredump */
|
|
|
|
case 's':
|
2015-06-25 22:03:53 +00:00
|
|
|
err = cn_printf(cn, "%d",
|
|
|
|
cprm->siginfo->si_signo);
|
2012-09-27 01:52:08 +00:00
|
|
|
break;
|
|
|
|
/* UNIX time of coredump */
|
|
|
|
case 't': {
|
2015-11-25 15:22:25 +00:00
|
|
|
time64_t time;
|
|
|
|
|
|
|
|
time = ktime_get_real_seconds();
|
|
|
|
err = cn_printf(cn, "%lld", time);
|
2012-09-27 01:52:08 +00:00
|
|
|
break;
|
|
|
|
}
|
|
|
|
/* hostname */
|
2013-07-03 22:08:20 +00:00
|
|
|
case 'h':
|
2012-09-27 01:52:08 +00:00
|
|
|
down_read(&uts_sem);
|
2013-07-03 22:08:20 +00:00
|
|
|
err = cn_esc_printf(cn, "%s",
|
2012-09-27 01:52:08 +00:00
|
|
|
utsname()->nodename);
|
|
|
|
up_read(&uts_sem);
|
|
|
|
break;
|
2020-08-12 01:36:20 +00:00
|
|
|
/* executable, could be changed by prctl PR_SET_NAME etc */
|
2013-07-03 22:08:20 +00:00
|
|
|
case 'e':
|
|
|
|
err = cn_esc_printf(cn, "%s", current->comm);
|
2012-09-27 01:52:08 +00:00
|
|
|
break;
|
2020-08-12 01:36:20 +00:00
|
|
|
/* file name of executable */
|
|
|
|
case 'f':
|
|
|
|
err = cn_print_exe_file(cn, true);
|
|
|
|
break;
|
2012-09-27 01:52:08 +00:00
|
|
|
case 'E':
|
2020-08-12 01:36:20 +00:00
|
|
|
err = cn_print_exe_file(cn, false);
|
2012-09-27 01:52:08 +00:00
|
|
|
break;
|
|
|
|
/* core limit size */
|
|
|
|
case 'c':
|
|
|
|
err = cn_printf(cn, "%lu",
|
|
|
|
rlimit(RLIMIT_CORE));
|
|
|
|
break;
|
|
|
|
default:
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
++pat_ptr;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (err)
|
|
|
|
return err;
|
|
|
|
}
|
|
|
|
|
2013-07-03 22:08:23 +00:00
|
|
|
out:
|
2012-09-27 01:52:08 +00:00
|
|
|
/* Backward compatibility with core_uses_pid:
|
|
|
|
*
|
|
|
|
* If core_pattern does not include a %p (as is the default)
|
|
|
|
* and core_uses_pid is set, then .%pid will be appended to
|
|
|
|
* the filename. Do not do this for piped commands. */
|
|
|
|
if (!ispipe && !pid_in_pattern && core_uses_pid) {
|
|
|
|
err = cn_printf(cn, ".%d", task_tgid_vnr(current));
|
|
|
|
if (err)
|
|
|
|
return err;
|
|
|
|
}
|
|
|
|
return ispipe;
|
|
|
|
}
|
|
|
|
|
2015-11-07 00:32:31 +00:00
|
|
|
static int zap_process(struct task_struct *start, int exit_code, int flags)
|
2012-09-27 01:52:08 +00:00
|
|
|
{
|
|
|
|
struct task_struct *t;
|
|
|
|
int nr = 0;
|
|
|
|
|
2015-11-07 00:32:31 +00:00
|
|
|
/* ignore all signals except SIGKILL, see prepare_signal() */
|
|
|
|
start->signal->flags = SIGNAL_GROUP_COREDUMP | flags;
|
2012-09-27 01:52:08 +00:00
|
|
|
start->signal->group_exit_code = exit_code;
|
|
|
|
start->signal->group_stop_count = 0;
|
|
|
|
|
2015-11-07 00:32:34 +00:00
|
|
|
for_each_thread(start, t) {
|
2012-09-27 01:52:08 +00:00
|
|
|
task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
|
|
|
|
if (t != current && t->mm) {
|
|
|
|
sigaddset(&t->pending.signal, SIGKILL);
|
|
|
|
signal_wake_up(t, 1);
|
|
|
|
nr++;
|
|
|
|
}
|
2015-11-07 00:32:34 +00:00
|
|
|
}
|
2012-09-27 01:52:08 +00:00
|
|
|
|
|
|
|
return nr;
|
|
|
|
}
|
|
|
|
|
2013-04-30 22:28:10 +00:00
|
|
|
static int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
|
|
|
|
struct core_state *core_state, int exit_code)
|
2012-09-27 01:52:08 +00:00
|
|
|
{
|
|
|
|
struct task_struct *g, *p;
|
|
|
|
unsigned long flags;
|
|
|
|
int nr = -EAGAIN;
|
|
|
|
|
|
|
|
spin_lock_irq(&tsk->sighand->siglock);
|
|
|
|
if (!signal_group_exit(tsk->signal)) {
|
|
|
|
mm->core_state = core_state;
|
2013-04-30 22:28:12 +00:00
|
|
|
tsk->signal->group_exit_task = tsk;
|
2015-11-07 00:32:31 +00:00
|
|
|
nr = zap_process(tsk, exit_code, 0);
|
2013-04-30 22:28:10 +00:00
|
|
|
clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
|
2012-09-27 01:52:08 +00:00
|
|
|
}
|
|
|
|
spin_unlock_irq(&tsk->sighand->siglock);
|
|
|
|
if (unlikely(nr < 0))
|
|
|
|
return nr;
|
|
|
|
|
2014-07-23 20:59:59 +00:00
|
|
|
tsk->flags |= PF_DUMPCORE;
|
2012-09-27 01:52:08 +00:00
|
|
|
if (atomic_read(&mm->mm_users) == nr + 1)
|
|
|
|
goto done;
|
|
|
|
/*
|
|
|
|
* We should find and kill all tasks which use this mm, and we should
|
|
|
|
* count them correctly into ->nr_threads. We don't take tasklist
|
|
|
|
* lock, but this is safe wrt:
|
|
|
|
*
|
|
|
|
* fork:
|
|
|
|
* None of sub-threads can fork after zap_process(leader). All
|
|
|
|
* processes which were created before this point should be
|
|
|
|
* visible to zap_threads() because copy_process() adds the new
|
|
|
|
* process to the tail of init_task.tasks list, and lock/unlock
|
|
|
|
* of ->siglock provides a memory barrier.
|
|
|
|
*
|
|
|
|
* do_exit:
|
2020-06-09 04:33:54 +00:00
|
|
|
* The caller holds mm->mmap_lock. This means that the task which
|
2012-09-27 01:52:08 +00:00
|
|
|
* uses this mm can't pass exit_mm(), so it can't exit or clear
|
|
|
|
* its ->mm.
|
|
|
|
*
|
|
|
|
* de_thread:
|
|
|
|
* It does list_replace_rcu(&leader->tasks, ¤t->tasks),
|
|
|
|
* we must see either old or new leader, this does not matter.
|
|
|
|
* However, it can change p->sighand, so lock_task_sighand(p)
|
2020-06-09 04:33:54 +00:00
|
|
|
* must be used. Since p->mm != NULL and we hold ->mmap_lock
|
2012-09-27 01:52:08 +00:00
|
|
|
* it can't fail.
|
|
|
|
*
|
|
|
|
* Note also that "g" can be the old leader with ->mm == NULL
|
|
|
|
* and already unhashed and thus removed from ->thread_group.
|
|
|
|
* This is OK, __unhash_process()->list_del_rcu() does not
|
|
|
|
* clear the ->next pointer, we will find the new leader via
|
|
|
|
* next_thread().
|
|
|
|
*/
|
|
|
|
rcu_read_lock();
|
|
|
|
for_each_process(g) {
|
|
|
|
if (g == tsk->group_leader)
|
|
|
|
continue;
|
|
|
|
if (g->flags & PF_KTHREAD)
|
|
|
|
continue;
|
2015-11-07 00:32:34 +00:00
|
|
|
|
|
|
|
for_each_thread(g, p) {
|
|
|
|
if (unlikely(!p->mm))
|
|
|
|
continue;
|
|
|
|
if (unlikely(p->mm == mm)) {
|
|
|
|
lock_task_sighand(p, &flags);
|
|
|
|
nr += zap_process(p, exit_code,
|
|
|
|
SIGNAL_GROUP_EXIT);
|
|
|
|
unlock_task_sighand(p, &flags);
|
2012-09-27 01:52:08 +00:00
|
|
|
}
|
2015-11-07 00:32:34 +00:00
|
|
|
break;
|
|
|
|
}
|
2012-09-27 01:52:08 +00:00
|
|
|
}
|
|
|
|
rcu_read_unlock();
|
|
|
|
done:
|
|
|
|
atomic_set(&core_state->nr_threads, nr);
|
|
|
|
return nr;
|
|
|
|
}
|
|
|
|
|
|
|
|
static int coredump_wait(int exit_code, struct core_state *core_state)
|
|
|
|
{
|
|
|
|
struct task_struct *tsk = current;
|
|
|
|
struct mm_struct *mm = tsk->mm;
|
|
|
|
int core_waiters = -EBUSY;
|
|
|
|
|
|
|
|
init_completion(&core_state->startup);
|
|
|
|
core_state->dumper.task = tsk;
|
|
|
|
core_state->dumper.next = NULL;
|
|
|
|
|
2020-06-09 04:33:25 +00:00
|
|
|
if (mmap_write_lock_killable(mm))
|
2016-05-23 23:25:57 +00:00
|
|
|
return -EINTR;
|
|
|
|
|
2012-09-27 01:52:08 +00:00
|
|
|
if (!mm->core_state)
|
|
|
|
core_waiters = zap_threads(tsk, mm, core_state, exit_code);
|
2020-06-09 04:33:25 +00:00
|
|
|
mmap_write_unlock(mm);
|
2012-09-27 01:52:08 +00:00
|
|
|
|
|
|
|
if (core_waiters > 0) {
|
|
|
|
struct core_thread *ptr;
|
|
|
|
|
2016-11-10 18:46:38 +00:00
|
|
|
freezer_do_not_count();
|
2012-09-27 01:52:08 +00:00
|
|
|
wait_for_completion(&core_state->startup);
|
2016-11-10 18:46:38 +00:00
|
|
|
freezer_count();
|
2012-09-27 01:52:08 +00:00
|
|
|
/*
|
|
|
|
* Wait for all the threads to become inactive, so that
|
|
|
|
* all the thread context (extended register state, like
|
|
|
|
* fpu etc) gets copied to the memory.
|
|
|
|
*/
|
|
|
|
ptr = core_state->dumper.next;
|
|
|
|
while (ptr != NULL) {
|
|
|
|
wait_task_inactive(ptr->task, 0);
|
|
|
|
ptr = ptr->next;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
return core_waiters;
|
|
|
|
}
|
|
|
|
|
2013-04-30 22:28:13 +00:00
|
|
|
static void coredump_finish(struct mm_struct *mm, bool core_dumped)
|
2012-09-27 01:52:08 +00:00
|
|
|
{
|
|
|
|
struct core_thread *curr, *next;
|
|
|
|
struct task_struct *task;
|
|
|
|
|
2013-04-30 22:28:12 +00:00
|
|
|
spin_lock_irq(¤t->sighand->siglock);
|
2013-04-30 22:28:13 +00:00
|
|
|
if (core_dumped && !__fatal_signal_pending(current))
|
|
|
|
current->signal->group_exit_code |= 0x80;
|
2013-04-30 22:28:12 +00:00
|
|
|
current->signal->group_exit_task = NULL;
|
|
|
|
current->signal->flags = SIGNAL_GROUP_EXIT;
|
|
|
|
spin_unlock_irq(¤t->sighand->siglock);
|
|
|
|
|
2012-09-27 01:52:08 +00:00
|
|
|
next = mm->core_state->dumper.next;
|
|
|
|
while ((curr = next) != NULL) {
|
|
|
|
next = curr->next;
|
|
|
|
task = curr->task;
|
|
|
|
/*
|
|
|
|
* see exit_mm(), curr->task must not see
|
|
|
|
* ->task == NULL before we read ->next.
|
|
|
|
*/
|
|
|
|
smp_mb();
|
|
|
|
curr->task = NULL;
|
|
|
|
wake_up_process(task);
|
|
|
|
}
|
|
|
|
|
|
|
|
mm->core_state = NULL;
|
|
|
|
}
|
|
|
|
|
2013-04-30 22:28:15 +00:00
|
|
|
static bool dump_interrupted(void)
|
|
|
|
{
|
|
|
|
/*
|
|
|
|
* SIGKILL or freezing() interrupt the coredumping. Perhaps we
|
|
|
|
* can do try_to_freeze() and check __fatal_signal_pending(),
|
|
|
|
* but then we need to teach dump_write() to restart and clear
|
|
|
|
* TIF_SIGPENDING.
|
|
|
|
*/
|
|
|
|
return signal_pending(current);
|
|
|
|
}
|
|
|
|
|
2012-09-27 01:52:08 +00:00
|
|
|
static void wait_for_dump_helpers(struct file *file)
|
|
|
|
{
|
2013-03-21 15:16:56 +00:00
|
|
|
struct pipe_inode_info *pipe = file->private_data;
|
2012-09-27 01:52:08 +00:00
|
|
|
|
|
|
|
pipe_lock(pipe);
|
|
|
|
pipe->readers++;
|
|
|
|
pipe->writers--;
|
pipe: use exclusive waits when reading or writing
This makes the pipe code use separate wait-queues and exclusive waiting
for readers and writers, avoiding a nasty thundering herd problem when
there are lots of readers waiting for data on a pipe (or, less commonly,
lots of writers waiting for a pipe to have space).
While this isn't a common occurrence in the traditional "use a pipe as a
data transport" case, where you typically only have a single reader and
a single writer process, there is one common special case: using a pipe
as a source of "locking tokens" rather than for data communication.
In particular, the GNU make jobserver code ends up using a pipe as a way
to limit parallelism, where each job consumes a token by reading a byte
from the jobserver pipe, and releases the token by writing a byte back
to the pipe.
This pattern is fairly traditional on Unix, and works very well, but
will waste a lot of time waking up a lot of processes when only a single
reader needs to be woken up when a writer releases a new token.
A simplified test-case of just this pipe interaction is to create 64
processes, and then pass a single token around between them (this
test-case also intentionally passes another token that gets ignored to
test the "wake up next" logic too, in case anybody wonders about it):
#include <unistd.h>
int main(int argc, char **argv)
{
int fd[2], counters[2];
pipe(fd);
counters[0] = 0;
counters[1] = -1;
write(fd[1], counters, sizeof(counters));
/* 64 processes */
fork(); fork(); fork(); fork(); fork(); fork();
do {
int i;
read(fd[0], &i, sizeof(i));
if (i < 0)
continue;
counters[0] = i+1;
write(fd[1], counters, (1+(i & 1)) *sizeof(int));
} while (counters[0] < 1000000);
return 0;
}
and in a perfect world, passing that token around should only cause one
context switch per transfer, when the writer of a token causes a
directed wakeup of just a single reader.
But with the "writer wakes all readers" model we traditionally had, on
my test box the above case causes more than an order of magnitude more
scheduling: instead of the expected ~1M context switches, "perf stat"
shows
231,852.37 msec task-clock # 15.857 CPUs utilized
11,250,961 context-switches # 0.049 M/sec
616,304 cpu-migrations # 0.003 M/sec
1,648 page-faults # 0.007 K/sec
1,097,903,998,514 cycles # 4.735 GHz
120,781,778,352 instructions # 0.11 insn per cycle
27,997,056,043 branches # 120.754 M/sec
283,581,233 branch-misses # 1.01% of all branches
14.621273891 seconds time elapsed
0.018243000 seconds user
3.611468000 seconds sys
before this commit.
After this commit, I get
5,229.55 msec task-clock # 3.072 CPUs utilized
1,212,233 context-switches # 0.232 M/sec
103,951 cpu-migrations # 0.020 M/sec
1,328 page-faults # 0.254 K/sec
21,307,456,166 cycles # 4.074 GHz
12,947,819,999 instructions # 0.61 insn per cycle
2,881,985,678 branches # 551.096 M/sec
64,267,015 branch-misses # 2.23% of all branches
1.702148350 seconds time elapsed
0.004868000 seconds user
0.110786000 seconds sys
instead. Much better.
[ Note! This kernel improvement seems to be very good at triggering a
race condition in the make jobserver (in GNU make 4.2.1) for me. It's
a long known bug that was fixed back in June 2017 by GNU make commit
b552b0525198 ("[SV 51159] Use a non-blocking read with pselect to
avoid hangs.").
But there wasn't a new release of GNU make until 4.3 on Jan 19 2020,
so a number of distributions may still have the buggy version. Some
have backported the fix to their 4.2.1 release, though, and even
without the fix it's quite timing-dependent whether the bug actually
is hit. ]
Josh Triplett says:
"I've been hammering on your pipe fix patch (switching to exclusive
wait queues) for a month or so, on several different systems, and I've
run into no issues with it. The patch *substantially* improves
parallel build times on large (~100 CPU) systems, both with parallel
make and with other things that use make's pipe-based jobserver.
All current distributions (including stable and long-term stable
distributions) have versions of GNU make that no longer have the
jobserver bug"
Tested-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-12-09 17:48:27 +00:00
|
|
|
wake_up_interruptible_sync(&pipe->rd_wait);
|
2013-04-30 22:28:17 +00:00
|
|
|
kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
|
|
|
|
pipe_unlock(pipe);
|
2012-09-27 01:52:08 +00:00
|
|
|
|
2013-04-30 22:28:17 +00:00
|
|
|
/*
|
|
|
|
* We actually want wait_event_freezable() but then we need
|
|
|
|
* to clear TIF_SIGPENDING and improve dump_interrupted().
|
|
|
|
*/
|
pipe: use exclusive waits when reading or writing
This makes the pipe code use separate wait-queues and exclusive waiting
for readers and writers, avoiding a nasty thundering herd problem when
there are lots of readers waiting for data on a pipe (or, less commonly,
lots of writers waiting for a pipe to have space).
While this isn't a common occurrence in the traditional "use a pipe as a
data transport" case, where you typically only have a single reader and
a single writer process, there is one common special case: using a pipe
as a source of "locking tokens" rather than for data communication.
In particular, the GNU make jobserver code ends up using a pipe as a way
to limit parallelism, where each job consumes a token by reading a byte
from the jobserver pipe, and releases the token by writing a byte back
to the pipe.
This pattern is fairly traditional on Unix, and works very well, but
will waste a lot of time waking up a lot of processes when only a single
reader needs to be woken up when a writer releases a new token.
A simplified test-case of just this pipe interaction is to create 64
processes, and then pass a single token around between them (this
test-case also intentionally passes another token that gets ignored to
test the "wake up next" logic too, in case anybody wonders about it):
#include <unistd.h>
int main(int argc, char **argv)
{
int fd[2], counters[2];
pipe(fd);
counters[0] = 0;
counters[1] = -1;
write(fd[1], counters, sizeof(counters));
/* 64 processes */
fork(); fork(); fork(); fork(); fork(); fork();
do {
int i;
read(fd[0], &i, sizeof(i));
if (i < 0)
continue;
counters[0] = i+1;
write(fd[1], counters, (1+(i & 1)) *sizeof(int));
} while (counters[0] < 1000000);
return 0;
}
and in a perfect world, passing that token around should only cause one
context switch per transfer, when the writer of a token causes a
directed wakeup of just a single reader.
But with the "writer wakes all readers" model we traditionally had, on
my test box the above case causes more than an order of magnitude more
scheduling: instead of the expected ~1M context switches, "perf stat"
shows
231,852.37 msec task-clock # 15.857 CPUs utilized
11,250,961 context-switches # 0.049 M/sec
616,304 cpu-migrations # 0.003 M/sec
1,648 page-faults # 0.007 K/sec
1,097,903,998,514 cycles # 4.735 GHz
120,781,778,352 instructions # 0.11 insn per cycle
27,997,056,043 branches # 120.754 M/sec
283,581,233 branch-misses # 1.01% of all branches
14.621273891 seconds time elapsed
0.018243000 seconds user
3.611468000 seconds sys
before this commit.
After this commit, I get
5,229.55 msec task-clock # 3.072 CPUs utilized
1,212,233 context-switches # 0.232 M/sec
103,951 cpu-migrations # 0.020 M/sec
1,328 page-faults # 0.254 K/sec
21,307,456,166 cycles # 4.074 GHz
12,947,819,999 instructions # 0.61 insn per cycle
2,881,985,678 branches # 551.096 M/sec
64,267,015 branch-misses # 2.23% of all branches
1.702148350 seconds time elapsed
0.004868000 seconds user
0.110786000 seconds sys
instead. Much better.
[ Note! This kernel improvement seems to be very good at triggering a
race condition in the make jobserver (in GNU make 4.2.1) for me. It's
a long known bug that was fixed back in June 2017 by GNU make commit
b552b0525198 ("[SV 51159] Use a non-blocking read with pselect to
avoid hangs.").
But there wasn't a new release of GNU make until 4.3 on Jan 19 2020,
so a number of distributions may still have the buggy version. Some
have backported the fix to their 4.2.1 release, though, and even
without the fix it's quite timing-dependent whether the bug actually
is hit. ]
Josh Triplett says:
"I've been hammering on your pipe fix patch (switching to exclusive
wait queues) for a month or so, on several different systems, and I've
run into no issues with it. The patch *substantially* improves
parallel build times on large (~100 CPU) systems, both with parallel
make and with other things that use make's pipe-based jobserver.
All current distributions (including stable and long-term stable
distributions) have versions of GNU make that no longer have the
jobserver bug"
Tested-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-12-09 17:48:27 +00:00
|
|
|
wait_event_interruptible(pipe->rd_wait, pipe->readers == 1);
|
2012-09-27 01:52:08 +00:00
|
|
|
|
2013-04-30 22:28:17 +00:00
|
|
|
pipe_lock(pipe);
|
2012-09-27 01:52:08 +00:00
|
|
|
pipe->readers--;
|
|
|
|
pipe->writers++;
|
|
|
|
pipe_unlock(pipe);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* umh_pipe_setup
|
|
|
|
* helper function to customize the process used
|
|
|
|
* to collect the core in userspace. Specifically
|
|
|
|
* it sets up a pipe and installs it as fd 0 (stdin)
|
|
|
|
* for the process. Returns 0 on success, or
|
|
|
|
* PTR_ERR on failure.
|
|
|
|
* Note that it also sets the core limit to 1. This
|
|
|
|
* is a special value that we use to trap recursive
|
|
|
|
* core dumps
|
|
|
|
*/
|
|
|
|
static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
|
|
|
|
{
|
|
|
|
struct file *files[2];
|
|
|
|
struct coredump_params *cp = (struct coredump_params *)info->data;
|
|
|
|
int err = create_pipe_files(files, 0);
|
|
|
|
if (err)
|
|
|
|
return err;
|
|
|
|
|
|
|
|
cp->file = files[1];
|
|
|
|
|
2012-10-16 17:30:07 +00:00
|
|
|
err = replace_fd(0, files[0], 0);
|
|
|
|
fput(files[0]);
|
2012-09-27 01:52:08 +00:00
|
|
|
/* and disallow core files too */
|
|
|
|
current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
|
|
|
|
|
2012-10-16 17:30:07 +00:00
|
|
|
return err;
|
2012-09-27 01:52:08 +00:00
|
|
|
}
|
|
|
|
|
2018-09-25 09:27:20 +00:00
|
|
|
void do_coredump(const kernel_siginfo_t *siginfo)
|
2012-09-27 01:52:08 +00:00
|
|
|
{
|
|
|
|
struct core_state core_state;
|
|
|
|
struct core_name cn;
|
|
|
|
struct mm_struct *mm = current->mm;
|
|
|
|
struct linux_binfmt * binfmt;
|
|
|
|
const struct cred *old_cred;
|
|
|
|
struct cred *cred;
|
|
|
|
int retval = 0;
|
|
|
|
int ispipe;
|
2019-08-03 04:49:05 +00:00
|
|
|
size_t *argv = NULL;
|
|
|
|
int argc = 0;
|
2012-09-27 01:52:08 +00:00
|
|
|
struct files_struct *displaced;
|
fs: if a coredump already exists, unlink and recreate with O_EXCL
It was possible for an attacking user to trick root (or another user) into
writing his coredumps into an attacker-readable, pre-existing file using
rename() or link(), causing the disclosure of secret data from the victim
process' virtual memory. Depending on the configuration, it was also
possible to trick root into overwriting system files with coredumps. Fix
that issue by never writing coredumps into existing files.
Requirements for the attack:
- The attack only applies if the victim's process has a nonzero
RLIMIT_CORE and is dumpable.
- The attacker can trick the victim into coredumping into an
attacker-writable directory D, either because the core_pattern is
relative and the victim's cwd is attacker-writable or because an
absolute core_pattern pointing to a world-writable directory is used.
- The attacker has one of these:
A: on a system with protected_hardlinks=0:
execute access to a folder containing a victim-owned,
attacker-readable file on the same partition as D, and the
victim-owned file will be deleted before the main part of the attack
takes place. (In practice, there are lots of files that fulfill
this condition, e.g. entries in Debian's /var/lib/dpkg/info/.)
This does not apply to most Linux systems because most distros set
protected_hardlinks=1.
B: on a system with protected_hardlinks=1:
execute access to a folder containing a victim-owned,
attacker-readable and attacker-writable file on the same partition
as D, and the victim-owned file will be deleted before the main part
of the attack takes place.
(This seems to be uncommon.)
C: on any system, independent of protected_hardlinks:
write access to a non-sticky folder containing a victim-owned,
attacker-readable file on the same partition as D
(This seems to be uncommon.)
The basic idea is that the attacker moves the victim-owned file to where
he expects the victim process to dump its core. The victim process dumps
its core into the existing file, and the attacker reads the coredump from
it.
If the attacker can't move the file because he does not have write access
to the containing directory, he can instead link the file to a directory
he controls, then wait for the original link to the file to be deleted
(because the kernel checks that the link count of the corefile is 1).
A less reliable variant that requires D to be non-sticky works with link()
and does not require deletion of the original link: link() the file into
D, but then unlink() it directly before the kernel performs the link count
check.
On systems with protected_hardlinks=0, this variant allows an attacker to
not only gain information from coredumps, but also clobber existing,
victim-writable files with coredumps. (This could theoretically lead to a
privilege escalation.)
Signed-off-by: Jann Horn <jann@thejh.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 22:38:28 +00:00
|
|
|
/* require nonrelative corefile path and be extra careful */
|
|
|
|
bool need_suid_safe = false;
|
2013-04-30 22:28:13 +00:00
|
|
|
bool core_dumped = false;
|
2012-09-27 01:52:08 +00:00
|
|
|
static atomic_t core_dump_count = ATOMIC_INIT(0);
|
|
|
|
struct coredump_params cprm = {
|
2012-10-05 00:15:29 +00:00
|
|
|
.siginfo = siginfo,
|
2012-11-05 18:11:26 +00:00
|
|
|
.regs = signal_pt_regs(),
|
2012-09-27 01:52:08 +00:00
|
|
|
.limit = rlimit(RLIMIT_CORE),
|
|
|
|
/*
|
|
|
|
* We must use the same mm->flags while dumping core to avoid
|
|
|
|
* inconsistency of bit flags, since this flag is not protected
|
|
|
|
* by any locks.
|
|
|
|
*/
|
|
|
|
.mm_flags = mm->flags,
|
|
|
|
};
|
|
|
|
|
2012-10-05 00:15:29 +00:00
|
|
|
audit_core_dumps(siginfo->si_signo);
|
2012-09-27 01:52:08 +00:00
|
|
|
|
|
|
|
binfmt = mm->binfmt;
|
|
|
|
if (!binfmt || !binfmt->core_dump)
|
|
|
|
goto fail;
|
|
|
|
if (!__get_dumpable(cprm.mm_flags))
|
|
|
|
goto fail;
|
|
|
|
|
|
|
|
cred = prepare_creds();
|
|
|
|
if (!cred)
|
|
|
|
goto fail;
|
|
|
|
/*
|
|
|
|
* We cannot trust fsuid as being the "true" uid of the process
|
|
|
|
* nor do we know its entire history. We only know it was tainted
|
|
|
|
* so we dump it as root in mode 2, and only into a controlled
|
|
|
|
* environment (pipe handler or fully qualified path).
|
|
|
|
*/
|
2013-02-28 01:03:15 +00:00
|
|
|
if (__get_dumpable(cprm.mm_flags) == SUID_DUMP_ROOT) {
|
2012-09-27 01:52:08 +00:00
|
|
|
/* Setuid core dump mode */
|
|
|
|
cred->fsuid = GLOBAL_ROOT_UID; /* Dump root private */
|
fs: if a coredump already exists, unlink and recreate with O_EXCL
It was possible for an attacking user to trick root (or another user) into
writing his coredumps into an attacker-readable, pre-existing file using
rename() or link(), causing the disclosure of secret data from the victim
process' virtual memory. Depending on the configuration, it was also
possible to trick root into overwriting system files with coredumps. Fix
that issue by never writing coredumps into existing files.
Requirements for the attack:
- The attack only applies if the victim's process has a nonzero
RLIMIT_CORE and is dumpable.
- The attacker can trick the victim into coredumping into an
attacker-writable directory D, either because the core_pattern is
relative and the victim's cwd is attacker-writable or because an
absolute core_pattern pointing to a world-writable directory is used.
- The attacker has one of these:
A: on a system with protected_hardlinks=0:
execute access to a folder containing a victim-owned,
attacker-readable file on the same partition as D, and the
victim-owned file will be deleted before the main part of the attack
takes place. (In practice, there are lots of files that fulfill
this condition, e.g. entries in Debian's /var/lib/dpkg/info/.)
This does not apply to most Linux systems because most distros set
protected_hardlinks=1.
B: on a system with protected_hardlinks=1:
execute access to a folder containing a victim-owned,
attacker-readable and attacker-writable file on the same partition
as D, and the victim-owned file will be deleted before the main part
of the attack takes place.
(This seems to be uncommon.)
C: on any system, independent of protected_hardlinks:
write access to a non-sticky folder containing a victim-owned,
attacker-readable file on the same partition as D
(This seems to be uncommon.)
The basic idea is that the attacker moves the victim-owned file to where
he expects the victim process to dump its core. The victim process dumps
its core into the existing file, and the attacker reads the coredump from
it.
If the attacker can't move the file because he does not have write access
to the containing directory, he can instead link the file to a directory
he controls, then wait for the original link to the file to be deleted
(because the kernel checks that the link count of the corefile is 1).
A less reliable variant that requires D to be non-sticky works with link()
and does not require deletion of the original link: link() the file into
D, but then unlink() it directly before the kernel performs the link count
check.
On systems with protected_hardlinks=0, this variant allows an attacker to
not only gain information from coredumps, but also clobber existing,
victim-writable files with coredumps. (This could theoretically lead to a
privilege escalation.)
Signed-off-by: Jann Horn <jann@thejh.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 22:38:28 +00:00
|
|
|
need_suid_safe = true;
|
2012-09-27 01:52:08 +00:00
|
|
|
}
|
|
|
|
|
2012-10-05 00:15:29 +00:00
|
|
|
retval = coredump_wait(siginfo->si_signo, &core_state);
|
2012-09-27 01:52:08 +00:00
|
|
|
if (retval < 0)
|
|
|
|
goto fail_creds;
|
|
|
|
|
|
|
|
old_cred = override_creds(cred);
|
|
|
|
|
2019-08-03 04:49:05 +00:00
|
|
|
ispipe = format_corename(&cn, &cprm, &argv, &argc);
|
2012-09-27 01:52:08 +00:00
|
|
|
|
2013-04-30 22:28:06 +00:00
|
|
|
if (ispipe) {
|
2019-08-03 04:49:05 +00:00
|
|
|
int argi;
|
2012-09-27 01:52:08 +00:00
|
|
|
int dump_count;
|
|
|
|
char **helper_argv;
|
2013-04-30 22:28:07 +00:00
|
|
|
struct subprocess_info *sub_info;
|
2012-09-27 01:52:08 +00:00
|
|
|
|
|
|
|
if (ispipe < 0) {
|
|
|
|
printk(KERN_WARNING "format_corename failed\n");
|
|
|
|
printk(KERN_WARNING "Aborting core\n");
|
2013-07-03 22:08:16 +00:00
|
|
|
goto fail_unlock;
|
2012-09-27 01:52:08 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
if (cprm.limit == 1) {
|
|
|
|
/* See umh_pipe_setup() which sets RLIMIT_CORE = 1.
|
|
|
|
*
|
|
|
|
* Normally core limits are irrelevant to pipes, since
|
|
|
|
* we're not writing to the file system, but we use
|
2015-02-05 13:35:05 +00:00
|
|
|
* cprm.limit of 1 here as a special value, this is a
|
2012-09-27 01:52:08 +00:00
|
|
|
* consistent way to catch recursive crashes.
|
|
|
|
* We can still crash if the core_pattern binary sets
|
|
|
|
* RLIM_CORE = !1, but it runs as root, and can do
|
|
|
|
* lots of stupid things.
|
|
|
|
*
|
|
|
|
* Note that we use task_tgid_vnr here to grab the pid
|
|
|
|
* of the process group leader. That way we get the
|
|
|
|
* right pid if a thread in a multi-threaded
|
|
|
|
* core_pattern process dies.
|
|
|
|
*/
|
|
|
|
printk(KERN_WARNING
|
|
|
|
"Process %d(%s) has RLIMIT_CORE set to 1\n",
|
|
|
|
task_tgid_vnr(current), current->comm);
|
|
|
|
printk(KERN_WARNING "Aborting core\n");
|
|
|
|
goto fail_unlock;
|
|
|
|
}
|
|
|
|
cprm.limit = RLIM_INFINITY;
|
|
|
|
|
|
|
|
dump_count = atomic_inc_return(&core_dump_count);
|
|
|
|
if (core_pipe_limit && (core_pipe_limit < dump_count)) {
|
|
|
|
printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
|
|
|
|
task_tgid_vnr(current), current->comm);
|
|
|
|
printk(KERN_WARNING "Skipping core dump\n");
|
|
|
|
goto fail_dropcount;
|
|
|
|
}
|
|
|
|
|
2019-08-03 04:49:05 +00:00
|
|
|
helper_argv = kmalloc_array(argc + 1, sizeof(*helper_argv),
|
|
|
|
GFP_KERNEL);
|
2012-09-27 01:52:08 +00:00
|
|
|
if (!helper_argv) {
|
|
|
|
printk(KERN_WARNING "%s failed to allocate memory\n",
|
|
|
|
__func__);
|
|
|
|
goto fail_dropcount;
|
|
|
|
}
|
2019-08-03 04:49:05 +00:00
|
|
|
for (argi = 0; argi < argc; argi++)
|
|
|
|
helper_argv[argi] = cn.corename + argv[argi];
|
|
|
|
helper_argv[argi] = NULL;
|
2012-09-27 01:52:08 +00:00
|
|
|
|
2013-04-30 22:28:07 +00:00
|
|
|
retval = -ENOMEM;
|
|
|
|
sub_info = call_usermodehelper_setup(helper_argv[0],
|
|
|
|
helper_argv, NULL, GFP_KERNEL,
|
|
|
|
umh_pipe_setup, NULL, &cprm);
|
|
|
|
if (sub_info)
|
|
|
|
retval = call_usermodehelper_exec(sub_info,
|
|
|
|
UMH_WAIT_EXEC);
|
|
|
|
|
2019-08-03 04:49:05 +00:00
|
|
|
kfree(helper_argv);
|
2012-09-27 01:52:08 +00:00
|
|
|
if (retval) {
|
2013-07-03 22:08:23 +00:00
|
|
|
printk(KERN_INFO "Core dump to |%s pipe failed\n",
|
2012-09-27 01:52:08 +00:00
|
|
|
cn.corename);
|
|
|
|
goto close_fail;
|
2013-04-30 22:28:06 +00:00
|
|
|
}
|
2012-09-27 01:52:08 +00:00
|
|
|
} else {
|
|
|
|
struct inode *inode;
|
2016-03-22 21:25:36 +00:00
|
|
|
int open_flags = O_CREAT | O_RDWR | O_NOFOLLOW |
|
|
|
|
O_LARGEFILE | O_EXCL;
|
2012-09-27 01:52:08 +00:00
|
|
|
|
|
|
|
if (cprm.limit < binfmt->min_coredump)
|
|
|
|
goto fail_unlock;
|
|
|
|
|
fs: if a coredump already exists, unlink and recreate with O_EXCL
It was possible for an attacking user to trick root (or another user) into
writing his coredumps into an attacker-readable, pre-existing file using
rename() or link(), causing the disclosure of secret data from the victim
process' virtual memory. Depending on the configuration, it was also
possible to trick root into overwriting system files with coredumps. Fix
that issue by never writing coredumps into existing files.
Requirements for the attack:
- The attack only applies if the victim's process has a nonzero
RLIMIT_CORE and is dumpable.
- The attacker can trick the victim into coredumping into an
attacker-writable directory D, either because the core_pattern is
relative and the victim's cwd is attacker-writable or because an
absolute core_pattern pointing to a world-writable directory is used.
- The attacker has one of these:
A: on a system with protected_hardlinks=0:
execute access to a folder containing a victim-owned,
attacker-readable file on the same partition as D, and the
victim-owned file will be deleted before the main part of the attack
takes place. (In practice, there are lots of files that fulfill
this condition, e.g. entries in Debian's /var/lib/dpkg/info/.)
This does not apply to most Linux systems because most distros set
protected_hardlinks=1.
B: on a system with protected_hardlinks=1:
execute access to a folder containing a victim-owned,
attacker-readable and attacker-writable file on the same partition
as D, and the victim-owned file will be deleted before the main part
of the attack takes place.
(This seems to be uncommon.)
C: on any system, independent of protected_hardlinks:
write access to a non-sticky folder containing a victim-owned,
attacker-readable file on the same partition as D
(This seems to be uncommon.)
The basic idea is that the attacker moves the victim-owned file to where
he expects the victim process to dump its core. The victim process dumps
its core into the existing file, and the attacker reads the coredump from
it.
If the attacker can't move the file because he does not have write access
to the containing directory, he can instead link the file to a directory
he controls, then wait for the original link to the file to be deleted
(because the kernel checks that the link count of the corefile is 1).
A less reliable variant that requires D to be non-sticky works with link()
and does not require deletion of the original link: link() the file into
D, but then unlink() it directly before the kernel performs the link count
check.
On systems with protected_hardlinks=0, this variant allows an attacker to
not only gain information from coredumps, but also clobber existing,
victim-writable files with coredumps. (This could theoretically lead to a
privilege escalation.)
Signed-off-by: Jann Horn <jann@thejh.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 22:38:28 +00:00
|
|
|
if (need_suid_safe && cn.corename[0] != '/') {
|
2012-09-27 01:52:08 +00:00
|
|
|
printk(KERN_WARNING "Pid %d(%s) can only dump core "\
|
|
|
|
"to fully qualified path!\n",
|
|
|
|
task_tgid_vnr(current), current->comm);
|
|
|
|
printk(KERN_WARNING "Skipping core dump\n");
|
|
|
|
goto fail_unlock;
|
|
|
|
}
|
|
|
|
|
fs: if a coredump already exists, unlink and recreate with O_EXCL
It was possible for an attacking user to trick root (or another user) into
writing his coredumps into an attacker-readable, pre-existing file using
rename() or link(), causing the disclosure of secret data from the victim
process' virtual memory. Depending on the configuration, it was also
possible to trick root into overwriting system files with coredumps. Fix
that issue by never writing coredumps into existing files.
Requirements for the attack:
- The attack only applies if the victim's process has a nonzero
RLIMIT_CORE and is dumpable.
- The attacker can trick the victim into coredumping into an
attacker-writable directory D, either because the core_pattern is
relative and the victim's cwd is attacker-writable or because an
absolute core_pattern pointing to a world-writable directory is used.
- The attacker has one of these:
A: on a system with protected_hardlinks=0:
execute access to a folder containing a victim-owned,
attacker-readable file on the same partition as D, and the
victim-owned file will be deleted before the main part of the attack
takes place. (In practice, there are lots of files that fulfill
this condition, e.g. entries in Debian's /var/lib/dpkg/info/.)
This does not apply to most Linux systems because most distros set
protected_hardlinks=1.
B: on a system with protected_hardlinks=1:
execute access to a folder containing a victim-owned,
attacker-readable and attacker-writable file on the same partition
as D, and the victim-owned file will be deleted before the main part
of the attack takes place.
(This seems to be uncommon.)
C: on any system, independent of protected_hardlinks:
write access to a non-sticky folder containing a victim-owned,
attacker-readable file on the same partition as D
(This seems to be uncommon.)
The basic idea is that the attacker moves the victim-owned file to where
he expects the victim process to dump its core. The victim process dumps
its core into the existing file, and the attacker reads the coredump from
it.
If the attacker can't move the file because he does not have write access
to the containing directory, he can instead link the file to a directory
he controls, then wait for the original link to the file to be deleted
(because the kernel checks that the link count of the corefile is 1).
A less reliable variant that requires D to be non-sticky works with link()
and does not require deletion of the original link: link() the file into
D, but then unlink() it directly before the kernel performs the link count
check.
On systems with protected_hardlinks=0, this variant allows an attacker to
not only gain information from coredumps, but also clobber existing,
victim-writable files with coredumps. (This could theoretically lead to a
privilege escalation.)
Signed-off-by: Jann Horn <jann@thejh.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 22:38:28 +00:00
|
|
|
/*
|
|
|
|
* Unlink the file if it exists unless this is a SUID
|
|
|
|
* binary - in that case, we're running around with root
|
|
|
|
* privs and don't want to unlink another user's coredump.
|
|
|
|
*/
|
|
|
|
if (!need_suid_safe) {
|
|
|
|
/*
|
|
|
|
* If it doesn't exist, that's fine. If there's some
|
|
|
|
* other problem, we'll catch it at the filp_open().
|
|
|
|
*/
|
2017-11-04 10:44:46 +00:00
|
|
|
do_unlinkat(AT_FDCWD, getname_kernel(cn.corename));
|
fs: if a coredump already exists, unlink and recreate with O_EXCL
It was possible for an attacking user to trick root (or another user) into
writing his coredumps into an attacker-readable, pre-existing file using
rename() or link(), causing the disclosure of secret data from the victim
process' virtual memory. Depending on the configuration, it was also
possible to trick root into overwriting system files with coredumps. Fix
that issue by never writing coredumps into existing files.
Requirements for the attack:
- The attack only applies if the victim's process has a nonzero
RLIMIT_CORE and is dumpable.
- The attacker can trick the victim into coredumping into an
attacker-writable directory D, either because the core_pattern is
relative and the victim's cwd is attacker-writable or because an
absolute core_pattern pointing to a world-writable directory is used.
- The attacker has one of these:
A: on a system with protected_hardlinks=0:
execute access to a folder containing a victim-owned,
attacker-readable file on the same partition as D, and the
victim-owned file will be deleted before the main part of the attack
takes place. (In practice, there are lots of files that fulfill
this condition, e.g. entries in Debian's /var/lib/dpkg/info/.)
This does not apply to most Linux systems because most distros set
protected_hardlinks=1.
B: on a system with protected_hardlinks=1:
execute access to a folder containing a victim-owned,
attacker-readable and attacker-writable file on the same partition
as D, and the victim-owned file will be deleted before the main part
of the attack takes place.
(This seems to be uncommon.)
C: on any system, independent of protected_hardlinks:
write access to a non-sticky folder containing a victim-owned,
attacker-readable file on the same partition as D
(This seems to be uncommon.)
The basic idea is that the attacker moves the victim-owned file to where
he expects the victim process to dump its core. The victim process dumps
its core into the existing file, and the attacker reads the coredump from
it.
If the attacker can't move the file because he does not have write access
to the containing directory, he can instead link the file to a directory
he controls, then wait for the original link to the file to be deleted
(because the kernel checks that the link count of the corefile is 1).
A less reliable variant that requires D to be non-sticky works with link()
and does not require deletion of the original link: link() the file into
D, but then unlink() it directly before the kernel performs the link count
check.
On systems with protected_hardlinks=0, this variant allows an attacker to
not only gain information from coredumps, but also clobber existing,
victim-writable files with coredumps. (This could theoretically lead to a
privilege escalation.)
Signed-off-by: Jann Horn <jann@thejh.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-09 22:38:28 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* There is a race between unlinking and creating the
|
|
|
|
* file, but if that causes an EEXIST here, that's
|
|
|
|
* fine - another process raced with us while creating
|
|
|
|
* the corefile, and the other process won. To userspace,
|
|
|
|
* what matters is that at least one of the two processes
|
|
|
|
* writes its coredump successfully, not which one.
|
|
|
|
*/
|
2016-03-22 21:25:36 +00:00
|
|
|
if (need_suid_safe) {
|
|
|
|
/*
|
|
|
|
* Using user namespaces, normal user tasks can change
|
|
|
|
* their current->fs->root to point to arbitrary
|
|
|
|
* directories. Since the intention of the "only dump
|
|
|
|
* with a fully qualified path" rule is to control where
|
|
|
|
* coredumps may be placed using root privileges,
|
|
|
|
* current->fs->root must not be used. Instead, use the
|
|
|
|
* root directory of init_task.
|
|
|
|
*/
|
|
|
|
struct path root;
|
|
|
|
|
|
|
|
task_lock(&init_task);
|
|
|
|
get_fs_root(init_task.fs, &root);
|
|
|
|
task_unlock(&init_task);
|
|
|
|
cprm.file = file_open_root(root.dentry, root.mnt,
|
|
|
|
cn.corename, open_flags, 0600);
|
|
|
|
path_put(&root);
|
|
|
|
} else {
|
|
|
|
cprm.file = filp_open(cn.corename, open_flags, 0600);
|
|
|
|
}
|
2012-09-27 01:52:08 +00:00
|
|
|
if (IS_ERR(cprm.file))
|
|
|
|
goto fail_unlock;
|
|
|
|
|
2013-01-23 22:07:38 +00:00
|
|
|
inode = file_inode(cprm.file);
|
2012-09-27 01:52:08 +00:00
|
|
|
if (inode->i_nlink > 1)
|
|
|
|
goto close_fail;
|
|
|
|
if (d_unhashed(cprm.file->f_path.dentry))
|
|
|
|
goto close_fail;
|
|
|
|
/*
|
|
|
|
* AK: actually i see no reason to not allow this for named
|
|
|
|
* pipes etc, but keep the previous behaviour for now.
|
|
|
|
*/
|
|
|
|
if (!S_ISREG(inode->i_mode))
|
|
|
|
goto close_fail;
|
|
|
|
/*
|
2015-09-09 22:38:30 +00:00
|
|
|
* Don't dump core if the filesystem changed owner or mode
|
|
|
|
* of the file during file creation. This is an issue when
|
|
|
|
* a process dumps core while its cwd is e.g. on a vfat
|
|
|
|
* filesystem.
|
2012-09-27 01:52:08 +00:00
|
|
|
*/
|
|
|
|
if (!uid_eq(inode->i_uid, current_fsuid()))
|
|
|
|
goto close_fail;
|
2015-09-09 22:38:30 +00:00
|
|
|
if ((inode->i_mode & 0677) != 0600)
|
|
|
|
goto close_fail;
|
2015-04-03 19:23:17 +00:00
|
|
|
if (!(cprm.file->f_mode & FMODE_CAN_WRITE))
|
2012-09-27 01:52:08 +00:00
|
|
|
goto close_fail;
|
|
|
|
if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
|
|
|
|
goto close_fail;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* get us an unshared descriptor table; almost always a no-op */
|
|
|
|
retval = unshare_files(&displaced);
|
|
|
|
if (retval)
|
|
|
|
goto close_fail;
|
|
|
|
if (displaced)
|
|
|
|
put_files_struct(displaced);
|
2013-05-04 18:45:54 +00:00
|
|
|
if (!dump_interrupted()) {
|
2020-04-16 16:28:59 +00:00
|
|
|
/*
|
|
|
|
* umh disabled with CONFIG_STATIC_USERMODEHELPER_PATH="" would
|
|
|
|
* have this set to NULL.
|
|
|
|
*/
|
|
|
|
if (!cprm.file) {
|
|
|
|
pr_info("Core dump to |%s disabled\n", cn.corename);
|
|
|
|
goto close_fail;
|
|
|
|
}
|
2013-05-04 18:45:54 +00:00
|
|
|
file_start_write(cprm.file);
|
|
|
|
core_dumped = binfmt->core_dump(&cprm);
|
|
|
|
file_end_write(cprm.file);
|
|
|
|
}
|
2012-09-27 01:52:08 +00:00
|
|
|
if (ispipe && core_pipe_limit)
|
|
|
|
wait_for_dump_helpers(cprm.file);
|
|
|
|
close_fail:
|
|
|
|
if (cprm.file)
|
|
|
|
filp_close(cprm.file, NULL);
|
|
|
|
fail_dropcount:
|
|
|
|
if (ispipe)
|
|
|
|
atomic_dec(&core_dump_count);
|
|
|
|
fail_unlock:
|
2019-08-03 04:49:05 +00:00
|
|
|
kfree(argv);
|
2012-09-27 01:52:08 +00:00
|
|
|
kfree(cn.corename);
|
2013-04-30 22:28:13 +00:00
|
|
|
coredump_finish(mm, core_dumped);
|
2012-09-27 01:52:08 +00:00
|
|
|
revert_creds(old_cred);
|
|
|
|
fail_creds:
|
|
|
|
put_cred(cred);
|
|
|
|
fail:
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Core dumping helper functions. These are the only things you should
|
|
|
|
* do on a core-file: use only these functions to write out all the
|
|
|
|
* necessary info.
|
|
|
|
*/
|
2013-10-05 19:32:35 +00:00
|
|
|
int dump_emit(struct coredump_params *cprm, const void *addr, int nr)
|
|
|
|
{
|
|
|
|
struct file *file = cprm->file;
|
2013-10-08 13:11:48 +00:00
|
|
|
loff_t pos = file->f_pos;
|
|
|
|
ssize_t n;
|
2016-05-11 22:16:37 +00:00
|
|
|
if (cprm->written + nr > cprm->limit)
|
2013-10-05 19:32:35 +00:00
|
|
|
return 0;
|
2020-10-16 03:12:43 +00:00
|
|
|
|
|
|
|
|
|
|
|
if (dump_interrupted())
|
|
|
|
return 0;
|
|
|
|
n = __kernel_write(file, addr, nr, &pos);
|
|
|
|
if (n != nr)
|
|
|
|
return 0;
|
|
|
|
file->f_pos = pos;
|
|
|
|
cprm->written += n;
|
|
|
|
cprm->pos += n;
|
|
|
|
|
2013-10-05 19:32:35 +00:00
|
|
|
return 1;
|
|
|
|
}
|
|
|
|
EXPORT_SYMBOL(dump_emit);
|
|
|
|
|
2013-10-08 13:26:08 +00:00
|
|
|
int dump_skip(struct coredump_params *cprm, size_t nr)
|
2012-09-27 01:52:08 +00:00
|
|
|
{
|
2013-10-08 13:26:08 +00:00
|
|
|
static char zeroes[PAGE_SIZE];
|
|
|
|
struct file *file = cprm->file;
|
2012-09-27 01:52:08 +00:00
|
|
|
if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
|
2013-04-30 22:28:15 +00:00
|
|
|
if (dump_interrupted() ||
|
2013-10-08 13:26:08 +00:00
|
|
|
file->f_op->llseek(file, nr, SEEK_CUR) < 0)
|
2012-09-27 01:52:08 +00:00
|
|
|
return 0;
|
2016-06-05 21:14:14 +00:00
|
|
|
cprm->pos += nr;
|
2013-10-08 13:26:08 +00:00
|
|
|
return 1;
|
2012-09-27 01:52:08 +00:00
|
|
|
} else {
|
2013-10-08 13:26:08 +00:00
|
|
|
while (nr > PAGE_SIZE) {
|
|
|
|
if (!dump_emit(cprm, zeroes, PAGE_SIZE))
|
|
|
|
return 0;
|
|
|
|
nr -= PAGE_SIZE;
|
2012-09-27 01:52:08 +00:00
|
|
|
}
|
2013-10-08 13:26:08 +00:00
|
|
|
return dump_emit(cprm, zeroes, nr);
|
2012-09-27 01:52:08 +00:00
|
|
|
}
|
|
|
|
}
|
2013-10-08 13:26:08 +00:00
|
|
|
EXPORT_SYMBOL(dump_skip);
|
2013-10-08 15:05:01 +00:00
|
|
|
|
2020-10-16 03:12:46 +00:00
|
|
|
#ifdef CONFIG_ELF_CORE
|
|
|
|
int dump_user_range(struct coredump_params *cprm, unsigned long start,
|
|
|
|
unsigned long len)
|
|
|
|
{
|
|
|
|
unsigned long addr;
|
|
|
|
|
|
|
|
for (addr = start; addr < start + len; addr += PAGE_SIZE) {
|
|
|
|
struct page *page;
|
|
|
|
int stop;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* To avoid having to allocate page tables for virtual address
|
|
|
|
* ranges that have never been used yet, and also to make it
|
|
|
|
* easy to generate sparse core files, use a helper that returns
|
|
|
|
* NULL when encountering an empty page table entry that would
|
|
|
|
* otherwise have been filled with the zero page.
|
|
|
|
*/
|
|
|
|
page = get_dump_page(addr);
|
|
|
|
if (page) {
|
|
|
|
void *kaddr = kmap(page);
|
|
|
|
|
|
|
|
stop = !dump_emit(cprm, kaddr, PAGE_SIZE);
|
|
|
|
kunmap(page);
|
|
|
|
put_page(page);
|
|
|
|
} else {
|
|
|
|
stop = !dump_skip(cprm, PAGE_SIZE);
|
|
|
|
}
|
|
|
|
if (stop)
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
return 1;
|
|
|
|
}
|
|
|
|
#endif
|
|
|
|
|
2013-10-08 15:05:01 +00:00
|
|
|
int dump_align(struct coredump_params *cprm, int align)
|
|
|
|
{
|
2016-06-05 21:14:14 +00:00
|
|
|
unsigned mod = cprm->pos & (align - 1);
|
2013-10-08 15:05:01 +00:00
|
|
|
if (align & (align - 1))
|
2013-11-16 02:55:52 +00:00
|
|
|
return 0;
|
|
|
|
return mod ? dump_skip(cprm, align - mod) : 1;
|
2013-10-08 15:05:01 +00:00
|
|
|
}
|
|
|
|
EXPORT_SYMBOL(dump_align);
|
2017-01-11 19:25:00 +00:00
|
|
|
|
|
|
|
/*
|
|
|
|
* Ensures that file size is big enough to contain the current file
|
|
|
|
* postion. This prevents gdb from complaining about a truncated file
|
|
|
|
* if the last "write" to the file was dump_skip.
|
|
|
|
*/
|
|
|
|
void dump_truncate(struct coredump_params *cprm)
|
|
|
|
{
|
|
|
|
struct file *file = cprm->file;
|
|
|
|
loff_t offset;
|
|
|
|
|
|
|
|
if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
|
|
|
|
offset = file->f_op->llseek(file, 0, SEEK_CUR);
|
|
|
|
if (i_size_read(file->f_mapping->host) < offset)
|
|
|
|
do_truncate(file->f_path.dentry, offset, 0, file);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
EXPORT_SYMBOL(dump_truncate);
|
2020-10-16 03:12:50 +00:00
|
|
|
|
|
|
|
/*
|
|
|
|
* The purpose of always_dump_vma() is to make sure that special kernel mappings
|
|
|
|
* that are useful for post-mortem analysis are included in every core dump.
|
|
|
|
* In that way we ensure that the core dump is fully interpretable later
|
|
|
|
* without matching up the same kernel and hardware config to see what PC values
|
|
|
|
* meant. These special mappings include - vDSO, vsyscall, and other
|
|
|
|
* architecture specific mappings
|
|
|
|
*/
|
|
|
|
static bool always_dump_vma(struct vm_area_struct *vma)
|
|
|
|
{
|
|
|
|
/* Any vsyscall mappings? */
|
|
|
|
if (vma == get_gate_vma(vma->vm_mm))
|
|
|
|
return true;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Assume that all vmas with a .name op should always be dumped.
|
|
|
|
* If this changes, a new vm_ops field can easily be added.
|
|
|
|
*/
|
|
|
|
if (vma->vm_ops && vma->vm_ops->name && vma->vm_ops->name(vma))
|
|
|
|
return true;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* arch_vma_name() returns non-NULL for special architecture mappings,
|
|
|
|
* such as vDSO sections.
|
|
|
|
*/
|
|
|
|
if (arch_vma_name(vma))
|
|
|
|
return true;
|
|
|
|
|
|
|
|
return false;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Decide how much of @vma's contents should be included in a core dump.
|
|
|
|
*/
|
binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot
In both binfmt_elf and binfmt_elf_fdpic, use a new helper
dump_vma_snapshot() to take a snapshot of the VMA list (including the gate
VMA, if we have one) while protected by the mmap_lock, and then use that
snapshot instead of walking the VMA list without locking.
An alternative approach would be to keep the mmap_lock held across the
entire core dumping operation; however, keeping the mmap_lock locked while
we may be blocked for an unbounded amount of time (e.g. because we're
dumping to a FUSE filesystem or so) isn't really optimal; the mmap_lock
blocks things like the ->release handler of userfaultfd, and we don't
really want critical system daemons to grind to a halt just because
someone "gifted" them SCM_RIGHTS to an eternally-locked userfaultfd, or
something like that.
Since both the normal ELF code and the FDPIC ELF code need this
functionality (and if any other binfmt wants to add coredump support in
the future, they'd probably need it, too), implement this with a common
helper in fs/coredump.c.
A downside of this approach is that we now need a bigger amount of kernel
memory per userspace VMA in the normal ELF case, and that we need O(n)
kernel memory in the FDPIC ELF case at all; but 40 bytes per VMA shouldn't
be terribly bad.
There currently is a data race between stack expansion and anything that
reads ->vm_start or ->vm_end under the mmap_lock held in read mode; to
mitigate that for core dumping, take the mmap_lock in write mode when
taking a snapshot of the VMA hierarchy. (If we only took the mmap_lock in
read mode, we could end up with a corrupted core dump if someone does
get_user_pages_remote() concurrently. Not really a major problem, but
taking the mmap_lock either way works here, so we might as well avoid the
issue.) (This doesn't do anything about the existing data races with stack
expansion in other mm code.)
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Link: http://lkml.kernel.org/r/20200827114932.3572699-6-jannh@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-10-16 03:12:54 +00:00
|
|
|
static unsigned long vma_dump_size(struct vm_area_struct *vma,
|
|
|
|
unsigned long mm_flags)
|
2020-10-16 03:12:50 +00:00
|
|
|
{
|
|
|
|
#define FILTER(type) (mm_flags & (1UL << MMF_DUMP_##type))
|
|
|
|
|
|
|
|
/* always dump the vdso and vsyscall sections */
|
|
|
|
if (always_dump_vma(vma))
|
|
|
|
goto whole;
|
|
|
|
|
|
|
|
if (vma->vm_flags & VM_DONTDUMP)
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
/* support for DAX */
|
|
|
|
if (vma_is_dax(vma)) {
|
|
|
|
if ((vma->vm_flags & VM_SHARED) && FILTER(DAX_SHARED))
|
|
|
|
goto whole;
|
|
|
|
if (!(vma->vm_flags & VM_SHARED) && FILTER(DAX_PRIVATE))
|
|
|
|
goto whole;
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* Hugetlb memory check */
|
|
|
|
if (is_vm_hugetlb_page(vma)) {
|
|
|
|
if ((vma->vm_flags & VM_SHARED) && FILTER(HUGETLB_SHARED))
|
|
|
|
goto whole;
|
|
|
|
if (!(vma->vm_flags & VM_SHARED) && FILTER(HUGETLB_PRIVATE))
|
|
|
|
goto whole;
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* Do not dump I/O mapped devices or special mappings */
|
|
|
|
if (vma->vm_flags & VM_IO)
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
/* By default, dump shared memory if mapped from an anonymous file. */
|
|
|
|
if (vma->vm_flags & VM_SHARED) {
|
|
|
|
if (file_inode(vma->vm_file)->i_nlink == 0 ?
|
|
|
|
FILTER(ANON_SHARED) : FILTER(MAPPED_SHARED))
|
|
|
|
goto whole;
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* Dump segments that have been written to. */
|
|
|
|
if ((!IS_ENABLED(CONFIG_MMU) || vma->anon_vma) && FILTER(ANON_PRIVATE))
|
|
|
|
goto whole;
|
|
|
|
if (vma->vm_file == NULL)
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
if (FILTER(MAPPED_PRIVATE))
|
|
|
|
goto whole;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* If this is the beginning of an executable file mapping,
|
|
|
|
* dump the first page to aid in determining what was mapped here.
|
|
|
|
*/
|
|
|
|
if (FILTER(ELF_HEADERS) &&
|
|
|
|
vma->vm_pgoff == 0 && (vma->vm_flags & VM_READ) &&
|
|
|
|
(READ_ONCE(file_inode(vma->vm_file)->i_mode) & 0111) != 0)
|
|
|
|
return PAGE_SIZE;
|
|
|
|
|
|
|
|
#undef FILTER
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
whole:
|
|
|
|
return vma->vm_end - vma->vm_start;
|
|
|
|
}
|
binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot
In both binfmt_elf and binfmt_elf_fdpic, use a new helper
dump_vma_snapshot() to take a snapshot of the VMA list (including the gate
VMA, if we have one) while protected by the mmap_lock, and then use that
snapshot instead of walking the VMA list without locking.
An alternative approach would be to keep the mmap_lock held across the
entire core dumping operation; however, keeping the mmap_lock locked while
we may be blocked for an unbounded amount of time (e.g. because we're
dumping to a FUSE filesystem or so) isn't really optimal; the mmap_lock
blocks things like the ->release handler of userfaultfd, and we don't
really want critical system daemons to grind to a halt just because
someone "gifted" them SCM_RIGHTS to an eternally-locked userfaultfd, or
something like that.
Since both the normal ELF code and the FDPIC ELF code need this
functionality (and if any other binfmt wants to add coredump support in
the future, they'd probably need it, too), implement this with a common
helper in fs/coredump.c.
A downside of this approach is that we now need a bigger amount of kernel
memory per userspace VMA in the normal ELF case, and that we need O(n)
kernel memory in the FDPIC ELF case at all; but 40 bytes per VMA shouldn't
be terribly bad.
There currently is a data race between stack expansion and anything that
reads ->vm_start or ->vm_end under the mmap_lock held in read mode; to
mitigate that for core dumping, take the mmap_lock in write mode when
taking a snapshot of the VMA hierarchy. (If we only took the mmap_lock in
read mode, we could end up with a corrupted core dump if someone does
get_user_pages_remote() concurrently. Not really a major problem, but
taking the mmap_lock either way works here, so we might as well avoid the
issue.) (This doesn't do anything about the existing data races with stack
expansion in other mm code.)
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Link: http://lkml.kernel.org/r/20200827114932.3572699-6-jannh@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-10-16 03:12:54 +00:00
|
|
|
|
|
|
|
static struct vm_area_struct *first_vma(struct task_struct *tsk,
|
|
|
|
struct vm_area_struct *gate_vma)
|
|
|
|
{
|
|
|
|
struct vm_area_struct *ret = tsk->mm->mmap;
|
|
|
|
|
|
|
|
if (ret)
|
|
|
|
return ret;
|
|
|
|
return gate_vma;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Helper function for iterating across a vma list. It ensures that the caller
|
|
|
|
* will visit `gate_vma' prior to terminating the search.
|
|
|
|
*/
|
|
|
|
static struct vm_area_struct *next_vma(struct vm_area_struct *this_vma,
|
|
|
|
struct vm_area_struct *gate_vma)
|
|
|
|
{
|
|
|
|
struct vm_area_struct *ret;
|
|
|
|
|
|
|
|
ret = this_vma->vm_next;
|
|
|
|
if (ret)
|
|
|
|
return ret;
|
|
|
|
if (this_vma == gate_vma)
|
|
|
|
return NULL;
|
|
|
|
return gate_vma;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Under the mmap_lock, take a snapshot of relevant information about the task's
|
|
|
|
* VMAs.
|
|
|
|
*/
|
|
|
|
int dump_vma_snapshot(struct coredump_params *cprm, int *vma_count,
|
|
|
|
struct core_vma_metadata **vma_meta,
|
|
|
|
size_t *vma_data_size_ptr)
|
|
|
|
{
|
|
|
|
struct vm_area_struct *vma, *gate_vma;
|
|
|
|
struct mm_struct *mm = current->mm;
|
|
|
|
int i;
|
|
|
|
size_t vma_data_size = 0;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Once the stack expansion code is fixed to not change VMA bounds
|
|
|
|
* under mmap_lock in read mode, this can be changed to take the
|
|
|
|
* mmap_lock in read mode.
|
|
|
|
*/
|
|
|
|
if (mmap_write_lock_killable(mm))
|
|
|
|
return -EINTR;
|
|
|
|
|
|
|
|
gate_vma = get_gate_vma(mm);
|
|
|
|
*vma_count = mm->map_count + (gate_vma ? 1 : 0);
|
|
|
|
|
|
|
|
*vma_meta = kvmalloc_array(*vma_count, sizeof(**vma_meta), GFP_KERNEL);
|
|
|
|
if (!*vma_meta) {
|
|
|
|
mmap_write_unlock(mm);
|
|
|
|
return -ENOMEM;
|
|
|
|
}
|
|
|
|
|
|
|
|
for (i = 0, vma = first_vma(current, gate_vma); vma != NULL;
|
|
|
|
vma = next_vma(vma, gate_vma), i++) {
|
|
|
|
struct core_vma_metadata *m = (*vma_meta) + i;
|
|
|
|
|
|
|
|
m->start = vma->vm_start;
|
|
|
|
m->end = vma->vm_end;
|
|
|
|
m->flags = vma->vm_flags;
|
|
|
|
m->dump_size = vma_dump_size(vma, cprm->mm_flags);
|
|
|
|
|
|
|
|
vma_data_size += m->dump_size;
|
|
|
|
}
|
|
|
|
|
|
|
|
mmap_write_unlock(mm);
|
|
|
|
|
|
|
|
if (WARN_ON(i != *vma_count))
|
|
|
|
return -EFAULT;
|
|
|
|
|
|
|
|
*vma_data_size_ptr = vma_data_size;
|
|
|
|
return 0;
|
|
|
|
}
|