@@ -5,8 +5,138 @@ Security bugs
55
66Linux kernel developers take security very seriously. As such, we'd
77like to know when a security bug is found so that it can be fixed and
8- disclosed as quickly as possible. Please report security bugs to the
9- Linux kernel security team.
8+ disclosed as quickly as possible.
9+
10+ Preparing your report
11+ ---------------------
12+
13+ Like with any bug report, a security bug report requires a lot of analysis work
14+ from the developers, so the more information you can share about the issue, the
15+ better. Please review the procedure outlined in
16+ Documentation/admin-guide/reporting-issues.rst if you are unclear about what
17+ information is helpful. The following information are absolutely necessary in
18+ **any ** security bug report:
19+
20+ * **affected kernel version range **: with no version indication, your report
21+ will not be processed. A significant part of reports are for bugs that
22+ have already been fixed, so it is extremely important that vulnerabilities
23+ are verified on recent versions (development tree or latest stable
24+ version), at least by verifying that the code has not changed since the
25+ version where it was detected.
26+
27+ * **description of the problem **: a detailed description of the problem, with
28+ traces showing its manifestation, and why you consider that the observed
29+ behavior as a problem in the kernel, is necessary.
30+
31+ * **reproducer **: developers will need to be able to reproduce the problem to
32+ consider a fix as effective. This includes both a way to trigger the issue
33+ and a way to confirm it happens. A reproducer with low complexity
34+ dependencies will be needed (source code, shell script, sequence of
35+ instructions, file-system image etc). Binary-only executables are not
36+ accepted. Working exploits are extremely helpful and will not be released
37+ without consent from the reporter, unless they are already public. By
38+ definition if an issue cannot be reproduced, it is not exploitable, thus it
39+ is not a security bug.
40+
41+ * **conditions **: if the bug depends on certain configuration options,
42+ sysctls, permissions, timing, code modifications etc, these should be
43+ indicated.
44+
45+ In addition, the following information are highly desirable:
46+
47+ * **suspected location of the bug **: the file names and functions where the
48+ bug is suspected to be present are very important, at least to help forward
49+ the report to the appropriate maintainers. When not possible (for example,
50+ "system freezes each time I run this command"), the security team will help
51+ identify the source of the bug.
52+
53+ * **a proposed fix **: bug reporters who have analyzed the cause of a bug in
54+ the source code almost always have an accurate idea on how to fix it,
55+ because they spent a long time studying it and its implications. Proposing
56+ a tested fix will save maintainers a lot of time, even if the fix ends up
57+ not being the right one, because it helps understand the bug. When
58+ proposing a tested fix, please always format it in a way that can be
59+ immediately merged (see Documentation/process/submitting-patches.rst).
60+ This will save some back-and-forth exchanges if it is accepted, and you
61+ will be credited for finding and fixing this issue. Note that in this case
62+ only a ``Signed-off-by: `` tag is needed, without ``Reported-by: `` when the
63+ reporter and author are the same.
64+
65+ * **mitigations **: very often during a bug analysis, some ways of mitigating
66+ the issue appear. It is useful to share them, as they can be helpful to
67+ keep end users protected during the time it takes them to apply the fix.
68+
69+ Identifying contacts
70+ --------------------
71+
72+ The most effective way to report a security bug is to send it directly to the
73+ affected subsystem's maintainers and Cc: the Linux kernel security team. Do
74+ not send it to a public list at this stage, unless you have good reasons to
75+ consider the issue as being public or trivial to discover (e.g. result of a
76+ widely available automated vulnerability scanning tool that can be repeated by
77+ anyone).
78+
79+ If you're sending a report for issues affecting multiple parts in the kernel,
80+ even if they're fairly similar issues, please send individual messages (think
81+ that maintainers will not all work on the issues at the same time). The only
82+ exception is when an issue concerns closely related parts maintained by the
83+ exact same subset of maintainers, and these parts are expected to be fixed all
84+ at once by the same commit, then it may be acceptable to report them at once.
85+
86+ One difficulty for most first-time reporters is to figure the right list of
87+ recipients to send a report to. In the Linux kernel, all official maintainers
88+ are trusted, so the consequences of accidentally including the wrong maintainer
89+ are essentially a bit more noise for that person, i.e. nothing dramatic. As
90+ such, a suitable method to figure the list of maintainers (which kernel
91+ security officers use) is to rely on the get_maintainer.pl script, tuned to
92+ only report maintainers. This script, when passed a file name, will look for
93+ its path in the MAINTAINERS file to figure a hierarchical list of relevant
94+ maintainers. Calling it a first time with the finest level of filtering will
95+ most of the time return a short list of this specific file's maintainers::
96+
97+ $ ./scripts/get_maintainer.pl --no-l --no-r --pattern-depth 1 \
98+ drivers/example.c
99+ Developer One <dev1@example.com> (maintainer:example driver)
100+ Developer Two <dev2@example.org> (maintainer:example driver)
101+
102+ These two maintainers should then receive the message. If the command does not
103+ return anything, it means the affected file is part of a wider subsystem, so we
104+ should be less specific::
105+
106+ $ ./scripts/get_maintainer.pl --no-l --no-r drivers/example.c
107+ Developer One <dev1@example.com> (maintainer:example subsystem)
108+ Developer Two <dev2@example.org> (maintainer:example subsystem)
109+ Developer Three <dev3@example.com> (maintainer:example subsystem [GENERAL])
110+ Developer Four <dev4@example.org> (maintainer:example subsystem [GENERAL])
111+
112+ Here, picking the first, most specific ones, is sufficient. When the list is
113+ long, it is possible to produce a comma-delimited e-mail address list on a
114+ single line suitable for use in the To: field of a mailer like this::
115+
116+ $ ./scripts/get_maintainer.pl --no-tree --no-l --no-r --no-n --m \
117+ --no-git-fallback --no-substatus --no-rolestats --no-multiline \
118+ --pattern-depth 1 drivers/example.c
119+ dev1@example.com, dev2@example.org
120+
121+ or this for the wider list::
122+
123+ $ ./scripts/get_maintainer.pl --no-tree --no-l --no-r --no-n --m \
124+ --no-git-fallback --no-substatus --no-rolestats --no-multiline \
125+ drivers/example.c
126+ dev1@example.com, dev2@example.org, dev3@example.com, dev4@example.org
127+
128+ If at this point you're still facing difficulties spotting the right
129+ maintainers, **and only in this case **, it's possible to send your report to
130+ the Linux kernel security team only. Your message will be triaged, and you
131+ will receive instructions about whom to contact, if needed. Your message may
132+ equally be forwarded as-is to the relevant maintainers.
133+
134+ Sending the report
135+ ------------------
136+
137+ Reports are to be sent over e-mail exclusively. Please use a working e-mail
138+ address, preferably the same that you want to appear in ``Reported-by `` tags
139+ if any. If unsure, send your report to yourself first.
10140
11141The security team and maintainers almost always require additional
12142information beyond what was initially provided in a report and rely on
@@ -18,20 +148,12 @@ run additional tests. Reports where the reporter does not respond promptly
18148or cannot effectively discuss their findings may be abandoned if the
19149communication does not quickly improve.
20150
21- As it is with any bug, the more information provided the easier it
22- will be to diagnose and fix. Please review the procedure outlined in
23- 'Documentation/admin-guide/reporting-issues.rst' if you are unclear about what
24- information is helpful. Any exploit code is very helpful and will not
25- be released without consent from the reporter unless it has already been
26- made public.
27-
151+ The report must be sent to maintainers, with the security team in ``Cc: ``.
28152The Linux kernel security team can be contacted by email at
29153<security@kernel.org>. This is a private list of security officers
30- who will help verify the bug report and develop and release a fix.
31- If you already have a fix, please include it with your report, as
32- that can speed up the process considerably. It is possible that the
33- security team will bring in extra help from area maintainers to
34- understand and fix the security vulnerability.
154+ who will help verify the bug report and assist developers working on a fix.
155+ It is possible that the security team will bring in extra help from area
156+ maintainers to understand and fix the security vulnerability.
35157
36158Please send **plain text ** emails without attachments where possible.
37159It is much harder to have a context-quoted discussion about a complex
@@ -42,7 +164,9 @@ reproduction steps, and follow it with a proposed fix, all in plain text.
42164Markdown, HTML and RST formatted reports are particularly frowned upon since
43165they're quite hard to read for humans and encourage to use dedicated viewers,
44166sometimes online, which by definition is not acceptable for a confidential
45- security report.
167+ security report. Note that some mailers tend to mangle formatting of plain
168+ text by default, please consult Documentation/process/email-clients.rst for
169+ more info.
46170
47171Disclosure and embargoed information
48172------------------------------------
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