mirror of
https://github.com/LadybirdBrowser/ladybird.git
synced 2025-05-07 11:42:51 +00:00
8233da3398
This makes pledge() ignore promises that would otherwise cause it to fail with EPERM, which is very useful for allowing programs to run under a "jail" so to speak, without having them termiate early due to a failing pledge() call.
74 lines
3.7 KiB
Markdown
74 lines
3.7 KiB
Markdown
## Name
|
|
|
|
pledge - reduce process capabilities
|
|
|
|
## Synopsis
|
|
|
|
```**c++
|
|
#include <unistd.h>
|
|
|
|
int pledge(const char* promises, const char* execpromises);
|
|
```
|
|
|
|
## Description
|
|
|
|
`pledge()` makes a promise to the kernel that from this moment on, the calling process will only use a subset of system functionality.
|
|
|
|
Functionality is divided into a curated set of promises (described below), which can be combined to cover the program's needs. Both arguments are space-separated lists of promises.
|
|
|
|
Note that `pledge()` can be called repeatedly to remove previously-pledged promises, but it can never regain capabilities once lost.
|
|
|
|
`promises` are applied to the current process, and will also be inherited by children created by [`fork`(2)](help://man/2/fork).
|
|
|
|
`execpromises` are applied if/when a new process image is created with [`exec`(2)](help://man/2/exec).
|
|
|
|
If `promises` or `execpromises` is null, the corresponding value is unchanged.
|
|
|
|
If the process later attempts to use any system functionality it has previously promised *not* to use, the process is instantly terminated. Note that a process that has not ever called `pledge()` is considered to not have made any promises, and is allowed use any system functionality (subject to regular permission checks).
|
|
|
|
`pledge()` is intended to be used in programs that want to sandbox themselves, either to limit the impact of a possible vulnerability exploitation, or before intentionally executing untrusted code.
|
|
|
|
## Promises
|
|
|
|
* `stdio`: Basic I/O, memory allocation, information about self, various non-destructive syscalls
|
|
* `thread`: The POSIX threading API (\*)
|
|
* `id`: Ability to change UID/GID
|
|
* `tty`: TTY related functionality
|
|
* `proc`: Process and scheduling related functionality
|
|
* `exec`: The [`exec`(2)](help://man/2/exec) syscall
|
|
* `unix`: UNIX local domain sockets
|
|
* `inet`: IPv4 domain sockets
|
|
* `accept`: May use [`accept`(2)](help://man/2/accept) to accept incoming socket connections on already listening sockets (\*)
|
|
* `rpath`: "Read" filesystem access
|
|
* `wpath`: "Write" filesystem access
|
|
* `cpath`: "Create" filesystem access
|
|
* `dpath`: Creating new device files
|
|
* `chown`: Changing file owner/group
|
|
* `fattr`: Changing file attributes/permissions
|
|
* `video`: May use [`ioctl`(2)](help://man/2/ioctl) and [`mmap`(2)](help://man/2/mmap) on framebuffer video devices
|
|
* `settime`: Changing the system time and date
|
|
* `setkeymap`: Changing the system keyboard layout (\*)
|
|
* `sigaction`: Change signal handlers and dispositions (\*)
|
|
* `sendfd`: Send file descriptors over a local socket
|
|
* `recvfd`: Receive file descriptors over a local socket
|
|
* `ptrace`: The [`ptrace`(2)](help://man/2/ptrace) syscall (\*)
|
|
* `prot_exec`: [`mmap`(2)](help://man/2/mmap) and [`mprotect`(2)](help://man/2/mprotect) with `PROT_EXEC`
|
|
* `map_fixed`: [`mmap`(2)](help://man/2/mmap) with `MAP_FIXED` or `MAP_FIXED_NOREPLACE` (\*)
|
|
* `no_error`: Ignore requests of pledge elevation going forwards, this is useful for enforcing _execpromises_ while the child process wants to ask for more upfront (Note that the elevation requests are _not_ granted, merely ignored), this is similar to the `error` pledge in OpenBSD.
|
|
|
|
Promises marked with an asterisk (\*) are SerenityOS specific extensions not supported by the original OpenBSD `pledge()`.
|
|
|
|
## Errors
|
|
|
|
* `EFAULT`: `promises` and/or `execpromises` are not null and not in readable memory.
|
|
* `EINVAL`: One or more invalid promises were specified.
|
|
* `EPERM`: An attempt to increase capabilities was rejected.
|
|
|
|
## History
|
|
|
|
The `pledge()` system call was first introduced by OpenBSD. The implementation in SerenityOS differs in many ways and is by no means final.
|
|
|
|
## See also
|
|
|
|
* [`unveil`(2)](help://man/2/unveil)
|
|
* [`Mitigations`(7)](help://man/7/Mitigations)
|