Message ID | 20190418161311.24197-1-stefanha@redhat.com |
---|---|
State | New |
Headers | show |
Series | security.rst: add Security Guide to developer docs | expand |
Hi Stefan, On 4/18/19 6:13 PM, Stefan Hajnoczi wrote: > At KVM Forum 2018 I gave a presentation on security in QEMU: > https://www.youtube.com/watch?v=YAdRf_hwxU8 (video) > https://vmsplice.net/~stefan/stefanha-kvm-forum-2018.pdf (slides) > > This patch adds a security guide to the developer docs. This document > covers things that developers should know about security in QEMU. It is > just a starting point that we can expand on later. I hope it will be > useful as a resource for new contributors and will save code reviewers > from explaining the same concepts many times. > > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> > --- > docs/devel/index.rst | 1 + > docs/devel/security.rst | 220 ++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 221 insertions(+) > create mode 100644 docs/devel/security.rst > > diff --git a/docs/devel/index.rst b/docs/devel/index.rst > index ebbab636ce..fd0b5fa387 100644 > --- a/docs/devel/index.rst > +++ b/docs/devel/index.rst > @@ -20,3 +20,4 @@ Contents: > stable-process > testing > decodetree > + security > diff --git a/docs/devel/security.rst b/docs/devel/security.rst > new file mode 100644 > index 0000000000..c6a6c9973d > --- /dev/null > +++ b/docs/devel/security.rst > @@ -0,0 +1,220 @@ > +============== > +Security Guide > +============== > +Overview > +-------- > +This guide covers security topics relevant to developers working on QEMU. It > +includes an explanation of the security requirements that QEMU gives its users, > +the architecture of the code, and secure coding practices. > + > +Security Requirements > +--------------------- > +QEMU supports many different use cases, some of which have stricter security > +requirements than others. The community has agreed on the overall security > +requirements that users may depend on. These requirements define what is > +considered supported from a security perspective. > + > +Virtualization Use Case > +~~~~~~~~~~~~~~~~~~~~~~~ > +The virtualization use case covers cloud and virtual private server (VPS) > +hosting, as well as traditional data center and desktop virtualization. These > +use cases rely on hardware virtualization extensions to execute guest code > +safely on the physical CPU at close-to-native speed. > + > +The following entities are **untrusted**, meaning that they may be buggy or > +malicious: > + > +* Guest > +* User-facing interfaces (e.g. VNC, SPICE, WebSocket) > +* Network protocols (e.g. NBD, live migration) > +* User-supplied files (e.g. disk images, kernels, device trees) What about pass-thru USB/PCI devices? > + > +Bugs affecting these entities are evaluated on whether they can cause damage in > +real-world use cases and treated as security bugs if this is the case. > + > +Non-virtualization Use Case > +~~~~~~~~~~~~~~~~~~~~~~~~~~~ > +The non-virtualization use case covers emulation using the Tiny Code Generator > +(TCG). In principle the TCG and device emulation code used in conjunction with > +the non-virtualization use case should meet the same security requirements as > +the virtualization use case. However, for historical reasons much of the > +non-virtualization use case code was not written with these security > +requirements in mind. > + > +Bugs affecting the non-virtualization use case are not considered security > +bugs at this time. Users with non-virtualization use cases must not rely on > +QEMU to provide guest isolation or any security guarantees. > + > +Architecture > +------------ > +This section describes the design principles that ensure the security > +requirements are met. > + > +Guest Isolation > +~~~~~~~~~~~~~~~ > +Guest isolation is the confinement of guest code to the virtual machine. When > +guest code gains control of execution on the host this is called escaping the > +virtual machine. Isolation also includes resource limits such as CPU, memory, > +disk, or network throttling. Guests must be unable to exceed their resource I'm unsure but I'd have written "... such as throttling of CPU, memory, disk or network". > +limits. > + > +QEMU presents an attack surface to the guest in the form of emulated devices. > +The guest must not be able to gain control of QEMU. Bugs in emulated devices > +could allow malicious guests to gain code execution in QEMU. At this point the > +guest has escaped the virtual machine and is able to act in the context of the > +QEMU process on the host. > + > +Guests often interact with other guests and share resources with them. A > +malicious guest must not gain control of other guests or access their data. > +Disk image files and network traffic must be protected from other guests unless > +explicitly shared between them by the user. > + > +Principle of Least Privilege > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > +The principle of least privilege states that each component only has access to > +the privileges necessary for its function. In the case of QEMU this means that > +each process only has access to resources belonging to the guest. > + > +The QEMU process should not have access to any resources that are inaccessible > +to the guest. This way the guest does not gain anything by escaping into the > +QEMU process since it already has access to those same resources from within > +the guest. > + > +Following the principle of least privilege immediately fulfills guest isolation > +requirements. For example, guest A only has access to its own disk image file > +``a.img`` and not guest B's disk image file ``b.img``. > + > +In reality certain resources are inaccessible to the guest but must be > +available to QEMU to perform its function. For example, host system calls are > +necessary for QEMU but are not exposed to guests. A guest that escapes into > +the QEMU process can then begin invoking host system calls. > + > +New features must be designed to follow the principle of least privilege. > +Should this not be possible for technical reasons, the security risk must be > +clearly documented so users are aware of the trade-off of enabling the feature. > + > +Isolation mechanisms > +~~~~~~~~~~~~~~~~~~~~ > +Several isolation mechanisms are available to realize this architecture of > +guest isolation and the principle of least privilege. With the exception of > +Linux seccomp, these mechanisms are all deployed by management tools that > +launch QEMU, such as libvirt. They are also platform-specific so they are only > +described briefly for Linux here. > + > +The fundamental isolation mechanism is that QEMU processes must run as > +**unprivileged users**. Sometimes it seems more convenient to launch QEMU as > +root to give it access to host devices (e.g. ``/dev/net/tun``) but this poses a > +huge security risk. File descriptor passing can be used to give an otherwise > +unprivileged QEMU process access to host devices without running QEMU as root. > + > +**SELinux** and **AppArmor** make it possible to confine processes beyond the > +traditional UNIX process and file permissions model. They restrict the QEMU > +process from accessing processes and files on the host system that are not > +needed by QEMU. > + > +**Resource limits** and **cgroup controllers** provide throughput and utilization > +limits on key resources such as CPU time, memory, and I/O bandwidth. > + > +**Linux namespaces** can be used to make process, file system, and other system > +resources unavailable to QEMU. A namespaced QEMU process is restricted to only > +those resources that were granted to it. > + > +**Linux seccomp** is available via the QEMU ``--sandbox`` option. It disables > +system calls that are not needed by QEMU, thereby reducing the host kernel > +attack surface. > + > +Secure coding practices > +----------------------- > +At the source code level there are several points to keep in mind. Both > +developers and security researchers must be aware of them so that they can > +develop safe code and audit existing code properly. > + > +General Secure C Coding Practices > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > +Most CVEs (security bugs) reported against QEMU are not specific to > +virtualization or emulation. They are simply C programming bugs. Therefore > +it's critical to be aware of common classes of security bugs. > + > +There is a wide selection of resources available covering secure C coding. For > +example, the `CERT C Coding Standard > +<https://wiki.sei.cmu.edu/confluence/display/c/SEI+CERT+C+Coding+Standard>`_ > +covers the most important classes of security bugs. > + > +Instead of describing them in detail here, only the names of the most important > +classes of security bugs are mentioned: > + > +* Buffer overflows > +* Use-after-free and double-free > +* Integer overflows > +* Format string vulnerabilities > + > +Some of these classes of bugs can be detected by analyzers. Static analysis is > +performed regularly by Coverity and the most obvious of these bugs are even > +reported by compilers. Dynamic analysis is possible with valgrind, tsan, and > +asan. > + > +Input Validation > +~~~~~~~~~~~~~~~~ > +Inputs from the guest or external sources (e.g. network, files) cannot be > +trusted and may be invalid. Inputs must be checked before using them in a way > +that could crash the program, expose host memory to the guest, or otherwise be > +exploitable by an attacker. > + > +The most sensitive attack surface is device emulation. All hardware register > +accesses and data read from guest memory must be validated. A typical example > +is a device that contains multiple units that are selectable by the guest via > +an index register:: > + > + typedef struct { > + ProcessingUnit unit[2]; > + ... > + } MyDeviceState; > + > + static void mydev_writel(void *opaque, uint32_t addr, uint32_t val) > + { > + MyDeviceState *mydev = opaque; > + ProcessingUnit *unit; > + > + switch (addr) { > + case MYDEV_SELECT_UNIT: > + unit = &mydev->unit[val]; <-- this input wasn't validated! > + ... > + } > + } > + > +If ``val`` is not in range [0, 1] then an out-of-bounds memory access will take > +place when ``unit`` is dereferenced. The code must check that ``val`` is 0 or > +1 and handle the case where it is invalid. > + > +Unexpected Device Accesses > +~~~~~~~~~~~~~~~~~~~~~~~~~~ > +The guest may access device registers in unusual orders or at unexpected > +moments. Device emulation code must not assume that the guest follows the > +typical "theory of operation" presented in driver writer manuals. The guest > +may make nonsense accesses to device registers such as starting operations > +before the device has been fully initialized. > + > +A related issue is that device emulation code must be prepared for unexpected > +device register accesses while asynchronous operations are in progress. A > +well-behaved guest might wait for a completion interrupt before accessing > +certain device registers. Device emulation code must handle the case where the > +guest overwrites registers or submits further requests before an ongoing > +request completes. Unexpected accesses must not cause memory corruption or > +leaks in QEMU. Might worth to tell such unexpected accesses might be logged with 'qemu_log_mask(LOG_GUEST_ERROR, ...) and audited with -d guest_errors? > + > +Live migration > +~~~~~~~~~~~~~~ > +Device state can be saved to disk image files and shared with other users. > +Live migration code must validate inputs when loading device state so an > +attacker cannot gain control by crafting invalid device states. Device state > +is therefore considered untrusted even though it is typically generated by QEMU > +itself. > + > +Guest Memory Access Races > +~~~~~~~~~~~~~~~~~~~~~~~~~ > +Guests with multiple vCPUs may modify guest RAM while device emulation code is > +running. Device emulation code must copy in descriptors and other guest RAM > +structures and only process the local copy. This prevents > +time-of-check-to-time-of-use (TOCTOU) race conditions that could cause QEMU to > +crash when a vCPU thread modifies guest RAM while device emulation is > +processing it. > Thanks for this document! Regards, Phil.
On Thu, Apr 18, 2019 at 06:47:18PM +0200, Philippe Mathieu-Daudé wrote: > On 4/18/19 6:13 PM, Stefan Hajnoczi wrote: > > +Virtualization Use Case > > +~~~~~~~~~~~~~~~~~~~~~~~ > > +The virtualization use case covers cloud and virtual private server (VPS) > > +hosting, as well as traditional data center and desktop virtualization. These > > +use cases rely on hardware virtualization extensions to execute guest code > > +safely on the physical CPU at close-to-native speed. > > + > > +The following entities are **untrusted**, meaning that they may be buggy or > > +malicious: > > + > > +* Guest > > +* User-facing interfaces (e.g. VNC, SPICE, WebSocket) > > +* Network protocols (e.g. NBD, live migration) > > +* User-supplied files (e.g. disk images, kernels, device trees) > > What about pass-thru USB/PCI devices? Can you give a real-world example? > > +Guest Isolation > > +~~~~~~~~~~~~~~~ > > +Guest isolation is the confinement of guest code to the virtual machine. When > > +guest code gains control of execution on the host this is called escaping the > > +virtual machine. Isolation also includes resource limits such as CPU, memory, > > +disk, or network throttling. Guests must be unable to exceed their resource > > I'm unsure but I'd have written "... such as throttling of CPU, memory, > disk or network". Will change in v2. > > +Unexpected Device Accesses > > +~~~~~~~~~~~~~~~~~~~~~~~~~~ > > +The guest may access device registers in unusual orders or at unexpected > > +moments. Device emulation code must not assume that the guest follows the > > +typical "theory of operation" presented in driver writer manuals. The guest > > +may make nonsense accesses to device registers such as starting operations > > +before the device has been fully initialized. > > + > > +A related issue is that device emulation code must be prepared for unexpected > > +device register accesses while asynchronous operations are in progress. A > > +well-behaved guest might wait for a completion interrupt before accessing > > +certain device registers. Device emulation code must handle the case where the > > +guest overwrites registers or submits further requests before an ongoing > > +request completes. Unexpected accesses must not cause memory corruption or > > +leaks in QEMU. > > Might worth to tell such unexpected accesses might be logged with > 'qemu_log_mask(LOG_GUEST_ERROR, ...) and audited with -d guest_errors? Will add in v2. Stefan
Stefan Hajnoczi <stefanha@redhat.com> 于2019年4月23日周二 下午4:49写道: > On Thu, Apr 18, 2019 at 06:47:18PM +0200, Philippe Mathieu-Daudé wrote: > > On 4/18/19 6:13 PM, Stefan Hajnoczi wrote: > > > +Virtualization Use Case > > > +~~~~~~~~~~~~~~~~~~~~~~~ > > > +The virtualization use case covers cloud and virtual private server > (VPS) > > > +hosting, as well as traditional data center and desktop > virtualization. These > > > +use cases rely on hardware virtualization extensions to execute guest > code > > > +safely on the physical CPU at close-to-native speed. > > > + > > > +The following entities are **untrusted**, meaning that they may be > buggy or > > > +malicious: > > > + > > > +* Guest > > > +* User-facing interfaces (e.g. VNC, SPICE, WebSocket) > > > +* Network protocols (e.g. NBD, live migration) > > > +* User-supplied files (e.g. disk images, kernels, device trees) > > > > What about pass-thru USB/PCI devices? > > Can you give a real-world example? > > Maybe Philippe means qemu maybe interact with the malicious USB/PCI devices. Just like usb-fuzzer recently added to syzkaller. I'm not sure how much qemu communicate with the real device in pass-thru(VFIO?). If there are too much, it may be take consideration. Thanks, Li Qiang > > > +Guest Isolation > > > +~~~~~~~~~~~~~~~ > > > +Guest isolation is the confinement of guest code to the virtual > machine. When > > > +guest code gains control of execution on the host this is called > escaping the > > > +virtual machine. Isolation also includes resource limits such as > CPU, memory, > > > +disk, or network throttling. Guests must be unable to exceed their > resource > > > > I'm unsure but I'd have written "... such as throttling of CPU, memory, > > disk or network". > > Will change in v2. > > > > +Unexpected Device Accesses > > > +~~~~~~~~~~~~~~~~~~~~~~~~~~ > > > +The guest may access device registers in unusual orders or at > unexpected > > > +moments. Device emulation code must not assume that the guest > follows the > > > +typical "theory of operation" presented in driver writer manuals. > The guest > > > +may make nonsense accesses to device registers such as starting > operations > > > +before the device has been fully initialized. > > > + > > > +A related issue is that device emulation code must be prepared for > unexpected > > > +device register accesses while asynchronous operations are in > progress. A > > > +well-behaved guest might wait for a completion interrupt before > accessing > > > +certain device registers. Device emulation code must handle the case > where the > > > +guest overwrites registers or submits further requests before an > ongoing > > > +request completes. Unexpected accesses must not cause memory > corruption or > > > +leaks in QEMU. > > > > Might worth to tell such unexpected accesses might be logged with > > 'qemu_log_mask(LOG_GUEST_ERROR, ...) and audited with -d guest_errors? > > Will add in v2. > > Stefan >
diff --git a/docs/devel/index.rst b/docs/devel/index.rst index ebbab636ce..fd0b5fa387 100644 --- a/docs/devel/index.rst +++ b/docs/devel/index.rst @@ -20,3 +20,4 @@ Contents: stable-process testing decodetree + security diff --git a/docs/devel/security.rst b/docs/devel/security.rst new file mode 100644 index 0000000000..c6a6c9973d --- /dev/null +++ b/docs/devel/security.rst @@ -0,0 +1,220 @@ +============== +Security Guide +============== +Overview +-------- +This guide covers security topics relevant to developers working on QEMU. It +includes an explanation of the security requirements that QEMU gives its users, +the architecture of the code, and secure coding practices. + +Security Requirements +--------------------- +QEMU supports many different use cases, some of which have stricter security +requirements than others. The community has agreed on the overall security +requirements that users may depend on. These requirements define what is +considered supported from a security perspective. + +Virtualization Use Case +~~~~~~~~~~~~~~~~~~~~~~~ +The virtualization use case covers cloud and virtual private server (VPS) +hosting, as well as traditional data center and desktop virtualization. These +use cases rely on hardware virtualization extensions to execute guest code +safely on the physical CPU at close-to-native speed. + +The following entities are **untrusted**, meaning that they may be buggy or +malicious: + +* Guest +* User-facing interfaces (e.g. VNC, SPICE, WebSocket) +* Network protocols (e.g. NBD, live migration) +* User-supplied files (e.g. disk images, kernels, device trees) + +Bugs affecting these entities are evaluated on whether they can cause damage in +real-world use cases and treated as security bugs if this is the case. + +Non-virtualization Use Case +~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The non-virtualization use case covers emulation using the Tiny Code Generator +(TCG). In principle the TCG and device emulation code used in conjunction with +the non-virtualization use case should meet the same security requirements as +the virtualization use case. However, for historical reasons much of the +non-virtualization use case code was not written with these security +requirements in mind. + +Bugs affecting the non-virtualization use case are not considered security +bugs at this time. Users with non-virtualization use cases must not rely on +QEMU to provide guest isolation or any security guarantees. + +Architecture +------------ +This section describes the design principles that ensure the security +requirements are met. + +Guest Isolation +~~~~~~~~~~~~~~~ +Guest isolation is the confinement of guest code to the virtual machine. When +guest code gains control of execution on the host this is called escaping the +virtual machine. Isolation also includes resource limits such as CPU, memory, +disk, or network throttling. Guests must be unable to exceed their resource +limits. + +QEMU presents an attack surface to the guest in the form of emulated devices. +The guest must not be able to gain control of QEMU. Bugs in emulated devices +could allow malicious guests to gain code execution in QEMU. At this point the +guest has escaped the virtual machine and is able to act in the context of the +QEMU process on the host. + +Guests often interact with other guests and share resources with them. A +malicious guest must not gain control of other guests or access their data. +Disk image files and network traffic must be protected from other guests unless +explicitly shared between them by the user. + +Principle of Least Privilege +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The principle of least privilege states that each component only has access to +the privileges necessary for its function. In the case of QEMU this means that +each process only has access to resources belonging to the guest. + +The QEMU process should not have access to any resources that are inaccessible +to the guest. This way the guest does not gain anything by escaping into the +QEMU process since it already has access to those same resources from within +the guest. + +Following the principle of least privilege immediately fulfills guest isolation +requirements. For example, guest A only has access to its own disk image file +``a.img`` and not guest B's disk image file ``b.img``. + +In reality certain resources are inaccessible to the guest but must be +available to QEMU to perform its function. For example, host system calls are +necessary for QEMU but are not exposed to guests. A guest that escapes into +the QEMU process can then begin invoking host system calls. + +New features must be designed to follow the principle of least privilege. +Should this not be possible for technical reasons, the security risk must be +clearly documented so users are aware of the trade-off of enabling the feature. + +Isolation mechanisms +~~~~~~~~~~~~~~~~~~~~ +Several isolation mechanisms are available to realize this architecture of +guest isolation and the principle of least privilege. With the exception of +Linux seccomp, these mechanisms are all deployed by management tools that +launch QEMU, such as libvirt. They are also platform-specific so they are only +described briefly for Linux here. + +The fundamental isolation mechanism is that QEMU processes must run as +**unprivileged users**. Sometimes it seems more convenient to launch QEMU as +root to give it access to host devices (e.g. ``/dev/net/tun``) but this poses a +huge security risk. File descriptor passing can be used to give an otherwise +unprivileged QEMU process access to host devices without running QEMU as root. + +**SELinux** and **AppArmor** make it possible to confine processes beyond the +traditional UNIX process and file permissions model. They restrict the QEMU +process from accessing processes and files on the host system that are not +needed by QEMU. + +**Resource limits** and **cgroup controllers** provide throughput and utilization +limits on key resources such as CPU time, memory, and I/O bandwidth. + +**Linux namespaces** can be used to make process, file system, and other system +resources unavailable to QEMU. A namespaced QEMU process is restricted to only +those resources that were granted to it. + +**Linux seccomp** is available via the QEMU ``--sandbox`` option. It disables +system calls that are not needed by QEMU, thereby reducing the host kernel +attack surface. + +Secure coding practices +----------------------- +At the source code level there are several points to keep in mind. Both +developers and security researchers must be aware of them so that they can +develop safe code and audit existing code properly. + +General Secure C Coding Practices +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Most CVEs (security bugs) reported against QEMU are not specific to +virtualization or emulation. They are simply C programming bugs. Therefore +it's critical to be aware of common classes of security bugs. + +There is a wide selection of resources available covering secure C coding. For +example, the `CERT C Coding Standard +<https://wiki.sei.cmu.edu/confluence/display/c/SEI+CERT+C+Coding+Standard>`_ +covers the most important classes of security bugs. + +Instead of describing them in detail here, only the names of the most important +classes of security bugs are mentioned: + +* Buffer overflows +* Use-after-free and double-free +* Integer overflows +* Format string vulnerabilities + +Some of these classes of bugs can be detected by analyzers. Static analysis is +performed regularly by Coverity and the most obvious of these bugs are even +reported by compilers. Dynamic analysis is possible with valgrind, tsan, and +asan. + +Input Validation +~~~~~~~~~~~~~~~~ +Inputs from the guest or external sources (e.g. network, files) cannot be +trusted and may be invalid. Inputs must be checked before using them in a way +that could crash the program, expose host memory to the guest, or otherwise be +exploitable by an attacker. + +The most sensitive attack surface is device emulation. All hardware register +accesses and data read from guest memory must be validated. A typical example +is a device that contains multiple units that are selectable by the guest via +an index register:: + + typedef struct { + ProcessingUnit unit[2]; + ... + } MyDeviceState; + + static void mydev_writel(void *opaque, uint32_t addr, uint32_t val) + { + MyDeviceState *mydev = opaque; + ProcessingUnit *unit; + + switch (addr) { + case MYDEV_SELECT_UNIT: + unit = &mydev->unit[val]; <-- this input wasn't validated! + ... + } + } + +If ``val`` is not in range [0, 1] then an out-of-bounds memory access will take +place when ``unit`` is dereferenced. The code must check that ``val`` is 0 or +1 and handle the case where it is invalid. + +Unexpected Device Accesses +~~~~~~~~~~~~~~~~~~~~~~~~~~ +The guest may access device registers in unusual orders or at unexpected +moments. Device emulation code must not assume that the guest follows the +typical "theory of operation" presented in driver writer manuals. The guest +may make nonsense accesses to device registers such as starting operations +before the device has been fully initialized. + +A related issue is that device emulation code must be prepared for unexpected +device register accesses while asynchronous operations are in progress. A +well-behaved guest might wait for a completion interrupt before accessing +certain device registers. Device emulation code must handle the case where the +guest overwrites registers or submits further requests before an ongoing +request completes. Unexpected accesses must not cause memory corruption or +leaks in QEMU. + +Live migration +~~~~~~~~~~~~~~ +Device state can be saved to disk image files and shared with other users. +Live migration code must validate inputs when loading device state so an +attacker cannot gain control by crafting invalid device states. Device state +is therefore considered untrusted even though it is typically generated by QEMU +itself. + +Guest Memory Access Races +~~~~~~~~~~~~~~~~~~~~~~~~~ +Guests with multiple vCPUs may modify guest RAM while device emulation code is +running. Device emulation code must copy in descriptors and other guest RAM +structures and only process the local copy. This prevents +time-of-check-to-time-of-use (TOCTOU) race conditions that could cause QEMU to +crash when a vCPU thread modifies guest RAM while device emulation is +processing it.
At KVM Forum 2018 I gave a presentation on security in QEMU: https://www.youtube.com/watch?v=YAdRf_hwxU8 (video) https://vmsplice.net/~stefan/stefanha-kvm-forum-2018.pdf (slides) This patch adds a security guide to the developer docs. This document covers things that developers should know about security in QEMU. It is just a starting point that we can expand on later. I hope it will be useful as a resource for new contributors and will save code reviewers from explaining the same concepts many times. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> --- docs/devel/index.rst | 1 + docs/devel/security.rst | 220 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 221 insertions(+) create mode 100644 docs/devel/security.rst