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https://github.com/dynup/kpatch
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update patch module terminology
Try to be more consistent with the terminology. In various places we call it a "hotpatch module", "hot patch module", or "patch module". How about we just call it a "patch module" everywhere?
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README.md
32
README.md
@ -60,11 +60,11 @@ Make a source patch against the kernel tree:
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# from a kernel git tree:
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git diff > /path/to/foo.patch
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Build the hot patch kernel module:
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Build the patch module:
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kpatch-build /path/to/foo.patch
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This outputs a hot patch module named `kpatch-foo.ko` in the current
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This outputs a patch module named `kpatch-foo.ko` in the current
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directory. Now apply it to the running kernel:
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sudo insmod kpatch-foo.ko
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@ -79,29 +79,29 @@ kpatch works at a function granularity: old functions are replaced with new
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ones. It has four main components:
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- **kpatch-build**: a collection of tools which convert a source diff patch to
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a hot patch module. They work by compiling the kernel both with and without
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the source patch, comparing the binaries, and generating a hot patch module
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a patch module. They work by compiling the kernel both with and without
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the source patch, comparing the binaries, and generating a patch module
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which includes new binary versions of the functions to be replaced.
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- **hot patch module**: a kernel module (.ko file) which includes the
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- **patch module**: a kernel module (.ko file) which includes the
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replacement functions and metadata about the original functions.
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- **kpatch core module**: a kernel module (.ko file) which provides an
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interface for the hot patch modules to register new functions for
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interface for the patch modules to register new functions for
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replacement. It uses the kernel ftrace subsystem to hook into the original
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function's mcount call instruction, so that a call to the original function
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is redirected to the replacement function.
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- **kpatch utility:** a command-line tool which allows a user to manage a
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collection of hot patch modules. One or more hot patch modules may be
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collection of patch modules. One or more patch modules may be
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configured to load at boot time, so that a system can remain patched
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even after a reboot into the same version of the kernel.
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### kpatch-build
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The "kpatch-build" command converts a source-level diff patch file to a hot
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patch kernel module. Most of its work is performed by the kpatch-build script
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The "kpatch-build" command converts a source-level diff patch file to a kernel
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patch module. Most of its work is performed by the kpatch-build script
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which uses a collection of utilities: `create-diff-object`,
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`add-patch-section`, and `link-vmlinux-syms`.
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@ -120,19 +120,19 @@ The primary steps in kpatch-build are:
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sections
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- Link all the output objects into a cumulative object
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- Use `add-patches-section` to add the .patches section that the
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core kpatch module uses to determine the list of functions that need
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kpatch core module uses to determine the list of functions that need
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to be redirected using ftrace
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- Generate the patch kernel module
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- Generate the patch module
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- Use `link-vmlinux-syms` to hardcode non-exported kernel symbols
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into the symbol table of the patch kernel module
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into the symbol table of the patch module
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### Patching
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The hot patch kernel modules register with the core module (`kpatch.ko`).
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The patch modules register with the core module (`kpatch.ko`).
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They provide information about original functions that need to be replaced, and
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corresponding function pointers to the replacement functions.
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The kpatch core module registers a trampoline function with ftrace. The
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The core module registers a trampoline function with ftrace. The
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trampoline function is called by ftrace immediately before the original
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function begins executing. This occurs with the help of the reserved mcount
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call at the beginning of every function, created by the gcc `-mfentry` flag.
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@ -160,7 +160,7 @@ Limitations
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- Patches which modify statically allocated data are not supported.
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kpatch-build will detect that and return an error. (In the future
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we will add a facility to support it. It will probably require the
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user to write code which runs at module loading time which manually
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user to write code which runs at patch module loading time which manually
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updates the data.)
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- Patches which change the way a function interacts with dynamically
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@ -183,7 +183,7 @@ ability to arbitrarily modify the kernel, with or without kpatch.
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**Q. How can I detect if somebody has patched the kernel?**
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We hope to create a new kernel TAINT flag which will get set whenever a kpatch
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We hope to create a new kernel TAINT flag which will get set whenever a patch
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module is loaded.
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Also, many distros ship with cryptographically signed kernel modules, and will
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@ -31,17 +31,17 @@ usage () {
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echo "usage: kpatch <command> [<args>]" >&2
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echo >&2
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echo "Valid commands:" >&2
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printf ' %-20s %s\n' "install <file>" "install hotpatch module to the kpatch DB" >&2
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printf ' %-20s %s\n' "uninstall <hotpatch>" "uninstall hotpatch module from the kpatch DB" >&2
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printf ' %-20s %s\n' "install <file>" "install patch module to the kpatch DB" >&2
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printf ' %-20s %s\n' "uninstall <patch>" "uninstall patch module from the kpatch DB" >&2
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echo >&2
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printf ' %-20s %s\n' "load --all" "load all installed hotpatch modules into the running kernel" >&2
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printf ' %-20s %s\n' "load <hotpatch>" "load installed hotpatch module to the running kernel" >&2
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printf ' %-20s %s\n' "unload <hotpatch>" "unload hotpatch module from the running kernel" >&2
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printf ' %-20s %s\n' "load --all" "load all installed patch modules into the running kernel" >&2
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printf ' %-20s %s\n' "load <patch>" "load installed patch module into the running kernel" >&2
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printf ' %-20s %s\n' "unload <patch>" "unload patch module from the running kernel" >&2
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echo >&2
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echo >&2
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printf ' %-20s %s\n' "info <hotpatch>" "show information about an installed hotpatch module" >&2
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printf ' %-20s %s\n' "info <patch>" "show information about an installed patch module" >&2
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echo >&2
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printf ' %-20s %s\n' "list" "list installed hotpatch modules" >&2
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printf ' %-20s %s\n' "list" "list installed patch modules" >&2
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exit 1
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}
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man/kpatch.1
22
man/kpatch.1
@ -12,25 +12,25 @@ the system.
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.SH OPTIONS
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install <file>
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install hotpatch module to the kpatch DB
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install patch module to the kpatch DB
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uninstall <hotpatch>
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uninstall hotpatch module from the kpatch DB
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uninstall <patch>
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uninstall patch module from the kpatch DB
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load --all
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load all enabled hotpatch modules into the running kernel
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load all installed patch modules into the running kernel
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load <hotpatch>
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load installed hotpatch module to the running kernel
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load <patch>
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load installed patch module into the running kernel
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unload <hotpatch>
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unload hotpatch module from the running kernel
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unload <patch>
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unload patch module from the running kernel
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info <hotpatch>
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show information about an installed hotpatch module
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info <patch>
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show information about an installed patch module
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list
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list installed hotpatch modules
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list installed patch modules
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.SH SEE ALSO
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kpatch-build(1)
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