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Disallow ptrace on greeter and kwin_wayland process on FreeBSD [... for the future]

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Summary:
Similar to[[ https://phabricator.kde.org/D1216 |  D1216 ]] add procctl call to disable ptrace on FreeBSD.

We cannot do the procfs-lookup to check whether the process is already being run inside gdb -- however, on FreeBSD, we could use the P_TRACED flag of the process to figure this out:
> sys/proc.h:#define P_TRACED        0x00800 /* Debugged process being traced. */

And the code would look something similar to

```
    pid_t pid = getpid();
    struct procstat *prstat = procstat_open_sysctl();
    struct kinfo_proc *procinfo;
    unsigned int cnt;
    procinfo = procstat_getprocs(prstat, KERN_PROC_PID, pid, &cnt);
    long p_flags = procinfo->ki_flag;
    int p_traced = p_flags & P_TRACED;
    if (p_traced != P_TRACED) {
        mode = PROC_TRACE_CTL_DISABLE;
        procctl(P_PID, getpid(), PROC_TRACE_CTL, &mode);
    }
    procstat_freeprocs(prstat,procinfo);
    procstat_close(prstat);
```

But as wayland is [far] in the future on FreeBSD, and that check above is a bit lengthy, I think it is enough if we add it once it is needed.

Reviewers: rakuco, graesslin

Reviewed By: graesslin

Subscribers: plasma-devel

Projects: #plasma

Differential Revision: https://phabricator.kde.org/D1425
This commit is contained in:
Tobias C. Berner 2016-05-10 08:49:58 +02:00
parent bd8f6d78f0
commit 2ea5feb35b
3 changed files with 22 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

9
CMakeLists.txt
View file

@ -300,7 +300,14 @@ check_include_files(malloc.h HAVE_MALLOC_H)
check_include_file("sys/prctl.h" HAVE_SYS_PRCTL_H)
check_symbol_exists(PR_SET_DUMPABLE "sys/prctl.h" HAVE_PR_SET_DUMPABLE)
add_feature_info("prctl-dumpable" HAVE_PR_SET_DUMPABLE "Required for disallow ptrace on kwin_wayland process")
check_include_file("sys/procctl.h" HAVE_SYS_PROCCTL_H)
check_symbol_exists(PROC_TRACE_CTL "sys/procctl.h" HAVE_PROC_TRACE_CTL)
if (HAVE_PR_SET_DUMPABLE OR HAVE_PROC_TRACE_CTL)
set(CAN_DISABLE_PTRACE TRUE)
endif()
add_feature_info("prctl/procctl tracing control"
CAN_DISABLE_PTRACE
"Required for disallowing ptrace on kwin_wayland process")
configure_file(config-kwin.h.cmake ${CMAKE_CURRENT_BINARY_DIR}/config-kwin.h )

2
config-kwin.h.cmake
View file

@ -17,6 +17,8 @@
#cmakedefine01 HAVE_WAYLAND_EGL
#cmakedefine01 HAVE_SYS_PRCTL_H
#cmakedefine01 HAVE_PR_SET_DUMPABLE
#cmakedefine01 HAVE_SYS_PROCCTL_H
#cmakedefine01 HAVE_PROC_TRACE_CTL
#cmakedefine01 HAVE_BREEZE_DECO
#if HAVE_BREEZE_DECO
#define BREEZE_KDECORATION_PLUGIN_ID "${BREEZE_KDECORATION_PLUGIN_ID}"

12
main_wayland.cpp
View file

@ -56,6 +56,10 @@ along with this program. If not, see <http://www.gnu.org/licenses/>.
#if HAVE_SYS_PRCTL_H
#include <sys/prctl.h>
#endif
#if HAVE_SYS_PROCCTL_H
#include <unistd.h>
#include <sys/procctl.h>
#endif
#include <iostream>
#include <iomanip>
@ -403,6 +407,14 @@ static void disablePtrace()
// disable ptrace in kwin_wayland
prctl(PR_SET_DUMPABLE, 0);
#endif
#if HAVE_PROC_TRACE_CTL
// FreeBSD's rudimentary procfs does not support /proc/<pid>/exe
// We could use the P_TRACED flag of the process to find out
// if the process is being debugged ond FreeBSD.
int mode = PROC_TRACE_CTL_DISABLE;
procctl(P_PID, getpid(), PROC_TRACE_CTL, &mode);
#endif
}
} // namespace