Lyude Paul <ly...@redhat.com> writes: > Looks good! One nitpick I'm not 100% sure about:
>> +#define CHECK_FOR_REQUIRED_ARGUMENT() \
>> + if (((i + 1) >= argc) || (!argv[i + 1])) {
>> \
>> + ErrorF("Required argument to %s not specified\n", argv[i]); \
>> + UseMsg(); \
>> + FatalError("Required argument to %s not specified\n", argv[i]);
> Is the double printing of "Required argument to %s not specified" here
> intentional?
I copied CHECK_FOR_REQUIRED_ARGUMENT from xf86Init.c where it does the
same thing. I assume this is intended to make sure the user understands
what error caused the server to exit -- you can see it both before and
after the long usage message.
>> + if (!xf86PrivsElevated())
>> + ErrorF("-masterfd <fd> use the specified fd as the DRM
>> master fd\n");
> I think it would be a better idea for us to show this argument description
> unconditionally, along with adding a note about setuid/setgid not being
> allowed with it
Sounds good.
Here's an updated patch with the usage message change suggested. Thanks
for reviewing!
From f122451b7f5be985036cae29df7126a7f25cc891 Mon Sep 17 00:00:00 2001
From: Keith Packard <kei...@keithp.com>
Date: Thu, 18 Jan 2018 18:07:29 -0800
Subject: [PATCH xserver] modesetting: Allow a DRM fd to be passed on command
line with -masterfd [v2]
This lets an application open a suitable DRM device and pass the file
descriptor to the mode setting driver through an X server command line
option, '-masterfd'.
There's a companion application, xlease, which creates a DRM master by
leasing an output from another X server. That is available at
git clone git://people.freedesktop.org/~keithp/xlease
v2:
Always print usage, but note that it can't be used if
setuid/gid
Suggested-by: Lyude Paul <ly...@redhat.com>
Signed-off-by: Keith Packard <kei...@keithp.com>
---
hw/xfree86/common/xf86Globals.c | 2 ++
hw/xfree86/common/xf86Priv.h | 1 +
hw/xfree86/drivers/modesetting/driver.c | 26 ++++++++++++++++++++++++-
hw/xfree86/drivers/modesetting/driver.h | 1 +
hw/xfree86/os-support/linux/lnx_init.c | 21 ++++++++++++++++++++
5 files changed, 50 insertions(+), 1 deletion(-)
diff --git a/hw/xfree86/common/xf86Globals.c b/hw/xfree86/common/xf86Globals.c
index e890f05c2..7cc7401a2 100644
--- a/hw/xfree86/common/xf86Globals.c
+++ b/hw/xfree86/common/xf86Globals.c
@@ -53,6 +53,8 @@ DevPrivateKeyRec xf86ScreenKeyRec;
ScrnInfoPtr *xf86Screens = NULL; /* List of ScrnInfos */
ScrnInfoPtr *xf86GPUScreens = NULL; /* List of ScrnInfos */
+int xf86DRMMasterFd = -1; /* Command line argument for DRM master file descriptor */
+
const unsigned char byte_reversed[256] = {
0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0,
0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70, 0xf0,
diff --git a/hw/xfree86/common/xf86Priv.h b/hw/xfree86/common/xf86Priv.h
index 4fe2b5f33..393af3900 100644
--- a/hw/xfree86/common/xf86Priv.h
+++ b/hw/xfree86/common/xf86Priv.h
@@ -93,6 +93,7 @@ extern _X_EXPORT int xf86LogVerbose; /* log file verbosity level */
extern ScrnInfoPtr *xf86GPUScreens; /* List of pointers to ScrnInfoRecs */
extern int xf86NumGPUScreens;
+extern _X_EXPORT int xf86DRMMasterFd; /* Command line argument for DRM master file descriptor */
#ifndef DEFAULT_VERBOSE
#define DEFAULT_VERBOSE 0
#endif
diff --git a/hw/xfree86/drivers/modesetting/driver.c b/hw/xfree86/drivers/modesetting/driver.c
index 306541f33..6f4637254 100644
--- a/hw/xfree86/drivers/modesetting/driver.c
+++ b/hw/xfree86/drivers/modesetting/driver.c
@@ -36,6 +36,7 @@
#include <unistd.h>
#include <fcntl.h>
#include "xf86.h"
+#include "xf86Priv.h"
#include "xf86_OSproc.h"
#include "compiler.h"
#include "xf86Pci.h"
@@ -194,11 +195,24 @@ modesettingEntPtr ms_ent_priv(ScrnInfoPtr scrn)
return pPriv->ptr;
}
+static int
+get_passed_fd(void)
+{
+ if (xf86DRMMasterFd >= 0) {
+ xf86DrvMsg(-1, X_INFO, "Using passed DRM master file descriptor %d\n", xf86DRMMasterFd);
+ return dup(xf86DRMMasterFd);
+ }
+ return -1;
+}
+
static int
open_hw(const char *dev)
{
int fd;
+ if ((fd = get_passed_fd()) != -1)
+ return fd;
+
if (dev)
fd = open(dev, O_RDWR | O_CLOEXEC, 0);
else {
@@ -818,6 +832,12 @@ ms_get_drm_master_fd(ScrnInfoPtr pScrn)
return TRUE;
}
+ ms->fd_passed = FALSE;
+ if ((ms->fd = get_passed_fd()) >= 0) {
+ ms->fd_passed = TRUE;
+ return TRUE;
+ }
+
#ifdef XSERVER_PLATFORM_BUS
if (pEnt->location.type == BUS_PLATFORM) {
#ifdef XF86_PDEV_SERVER_FD
@@ -1502,6 +1522,9 @@ SetMaster(ScrnInfoPtr pScrn)
return TRUE;
#endif
+ if (ms->fd_passed)
+ return TRUE;
+
ret = drmSetMaster(ms->fd);
if (ret)
xf86DrvMsg(pScrn->scrnIndex, X_ERROR, "drmSetMaster failed: %s\n",
@@ -1754,7 +1777,8 @@ LeaveVT(ScrnInfoPtr pScrn)
return;
#endif
- drmDropMaster(ms->fd);
+ if (!ms->fd_passed)
+ drmDropMaster(ms->fd);
}
/*
diff --git a/hw/xfree86/drivers/modesetting/driver.h b/hw/xfree86/drivers/modesetting/driver.h
index 55f3400e2..c8db4b8a4 100644
--- a/hw/xfree86/drivers/modesetting/driver.h
+++ b/hw/xfree86/drivers/modesetting/driver.h
@@ -84,6 +84,7 @@ struct ms_drm_queue {
typedef struct _modesettingRec {
int fd;
+ Bool fd_passed;
int Chipset;
EntityInfoPtr pEnt;
diff --git a/hw/xfree86/os-support/linux/lnx_init.c b/hw/xfree86/os-support/linux/lnx_init.c
index a00002464..039dc4a4d 100644
--- a/hw/xfree86/os-support/linux/lnx_init.c
+++ b/hw/xfree86/os-support/linux/lnx_init.c
@@ -346,6 +346,13 @@ xf86CloseConsole(void)
close(xf86Info.consoleFd); /* make the vt-manager happy */
}
+#define CHECK_FOR_REQUIRED_ARGUMENT() \
+ if (((i + 1) >= argc) || (!argv[i + 1])) { \
+ ErrorF("Required argument to %s not specified\n", argv[i]); \
+ UseMsg(); \
+ FatalError("Required argument to %s not specified\n", argv[i]); \
+ }
+
int
xf86ProcessArgument(int argc, char *argv[], int i)
{
@@ -366,6 +373,19 @@ xf86ProcessArgument(int argc, char *argv[], int i)
}
return 1;
}
+
+ if (!strcmp(argv[i], "-masterfd")) {
+ CHECK_FOR_REQUIRED_ARGUMENT();
+ if (xf86PrivsElevated())
+ FatalError("\nCannot specify -masterfd when server is setuid/setgid\n");
+ if (sscanf(argv[++i], "%d", &xf86DRMMasterFd) != 1) {
+ UseMsg();
+ xf86DRMMasterFd = -1;
+ return 0;
+ }
+ return 2;
+ }
+
return 0;
}
@@ -375,4 +395,5 @@ xf86UseMsg(void)
ErrorF("vtXX use the specified VT number\n");
ErrorF("-keeptty ");
ErrorF("don't detach controlling tty (for debugging only)\n");
+ ErrorF("-masterfd <fd> use the specified fd as the DRM master fd (not if setuid/gid)\n");
}
--
2.17.1
-- -keith
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