Add readme

README

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-Syscall-Intercept allows you to intercept syscalls issued by programs and then block or log them according to a config file.
+# syscall-interceptor
+
+A program that intercepts syscalls issued by other programs and logs/blocks them.
+
+## Configuring:
+The configuration is the `config.yml` file in the root of the repository.
+It only requires the `syscalls` field, however the `log_file` field should also be configured.
+An example configuration that blocks the `umount2(2)` syscall with the `MNT_DETACH` flag, which gets called when running `umount -l`:
+```
+log_file: /some/random/path
+syscalls:
+  - umount2
+    log: true
+    block: true
+    arg0: 1
+    arg0_char: false
+```
+the name of the object is what gets interpreted as the syscall name, here the name `umount2` is taken, but `SYS_umount2` would also be accepted.
+each syscall object can have a total of 6 args, reaching from arg0 to arg5, each also having an Argo_char option, which needs to be set if the argN field is set.
+The argN_char option tells the parser if the argument is a string argument, e.g. if its a path, or if it a long, e.g. flags that can be raised, like `MNT_DETACH`.
+In the example, arg0 is set to a long of value 1, this corresponds to the `MNT_DETACH` flag, if, for example, the syscall should only be blocked if `MNT_DETACH` _and_ `MNT_FORCE` are set, then the result of a bitwise or (|=) with `MNT_DETACH` and `MNT_FORCE` (which is 3) should be set to arg0:
+```
+log_file: /some/random/path
+syscalls:
+  - umount2
+    log: true
+    block: true
+    arg0: 3
+    arg0_char: false
+```
+
+In the future an extra tool may be developed to either fully generate or at least assist with the generation of a configuration file.
+
+## Building
+Dependencies:
+- gcc (or equivalent c compiler)
+- autotools
+- [syscall_intercept](https://github.com/pmem/syscall_intercept)
+
+assuming `config.yml` has already been properly adjusted:
+```
+autoreconf --install
+./configure
+make
+```
+The resulting shared object file will be placed in `src/.libs`
+
+## Usage
+To activate syscall-interceptor, libsyscall_interceptor.so will have to be preloaded.
+This can be done with the `LD_PRELOAD` environment variable:
+`LD_PRELOAD=/path/to/libsyscall_interceptor.so <command>`

README.md

@@ -0,0 +1,51 @@
+# syscall-interceptor
+
+A program that intercepts syscalls issued by other programs and logs/blocks them.
+
+## Configuring:
+The configuration is the `config.yml` file in the root of the repository.
+It only requires the `syscalls` field, however the `log_file` field should also be configured.
+An example configuration that blocks the `umount2(2)` syscall with the `MNT_DETACH` flag, which gets called when running `umount -l`:
+```
+log_file: /some/random/path
+syscalls:
+  - umount2
+    log: true
+    block: true
+    arg0: 1
+    arg0_char: false
+```
+the name of the object is what gets interpreted as the syscall name, here the name `umount2` is taken, but `SYS_umount2` would also be accepted.
+each syscall object can have a total of 6 args, reaching from arg0 to arg5, each also having an Argo_char option, which needs to be set if the argN field is set.
+The argN_char option tells the parser if the argument is a string argument, e.g. if its a path, or if it a long, e.g. flags that can be raised, like `MNT_DETACH`.
+In the example, arg0 is set to a long of value 1, this corresponds to the `MNT_DETACH` flag, if, for example, the syscall should only be blocked if `MNT_DETACH` _and_ `MNT_FORCE` are set, then the result of a bitwise or (|=) with `MNT_DETACH` and `MNT_FORCE` (which is 3) should be set to arg0:
+```
+log_file: /some/random/path
+syscalls:
+  - umount2
+    log: true
+    block: true
+    arg0: 3
+    arg0_char: false
+```
+
+In the future an extra tool may be developed to either fully generate or at least assist with the generation of a configuration file.
+
+## Building
+Dependencies:
+- gcc (or equivalent c compiler)
+- autotools
+- [syscall_intercept](https://github.com/pmem/syscall_intercept)
+
+assuming `config.yml` has already been properly adjusted:
+```
+autoreconf --install
+./configure
+make
+```
+The resulting shared object file will be placed in `src/.libs`
+
+## Usage
+To activate syscall-interceptor, libsyscall_interceptor.so will have to be preloaded.
+This can be done with the `LD_PRELOAD` environment variable:
+`LD_PRELOAD=/path/to/libsyscall_interceptor.so <command>`