This patch implements new SNDRV_PCM_IOCTL_ANONYMOUS_DUP ioctl which returns the new duplicated anonymous inode file descriptor (anon_inode:snd-pcm) which can be passed to the restricted clients.
This patch is meant to be the alternative for the dma-buf interface. Both implementation have some pros and cons:
anon_inode:dmabuf
- a bit standard export API for the DMA buffers - fencing for the concurrent access [1] - driver/kernel interface for the DMA buffer [1] - multiple attach/detach scheme [1]
[1] the real usage for the sound PCM is unknown at the moment for this feature
anon_inode:snd-pcm
- simple (no problem with ref-counting, non-standard mmap implementation etc.) - allow to use more sound interfaces for the file descriptor like status ioctls - more fine grained security policies (another anon_inode name unshared with other drivers)
Signed-off-by: Jaroslav Kysela perex@perex.cz Reviewed-by: Takashi Iwai tiwai@suse.de --- include/sound/pcm.h | 8 +++--- include/uapi/sound/asound.h | 3 +- sound/core/oss/pcm_oss.c | 2 +- sound/core/pcm.c | 13 ++++----- sound/core/pcm_compat.c | 1 + sound/core/pcm_native.c | 67 +++++++++++++++++++++++++++++++++++++++++---- 6 files changed, 75 insertions(+), 19 deletions(-)
diff --git a/include/sound/pcm.h b/include/sound/pcm.h index ca20f80f8976..b79ffaa0241d 100644 --- a/include/sound/pcm.h +++ b/include/sound/pcm.h @@ -579,11 +579,11 @@ static inline int snd_pcm_suspend_all(struct snd_pcm *pcm) } #endif int snd_pcm_kernel_ioctl(struct snd_pcm_substream *substream, unsigned int cmd, void *arg); -int snd_pcm_open_substream(struct snd_pcm *pcm, int stream, struct file *file, - struct snd_pcm_substream **rsubstream); +int snd_pcm_open_substream(struct snd_pcm *pcm, int stream, int subdevice, + struct file *file, struct snd_pcm_substream **rsubstream); void snd_pcm_release_substream(struct snd_pcm_substream *substream); -int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream, struct file *file, - struct snd_pcm_substream **rsubstream); +int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream, int subdevice, + struct file *file, struct snd_pcm_substream **rsubstream); void snd_pcm_detach_substream(struct snd_pcm_substream *substream); int snd_pcm_mmap_data(struct snd_pcm_substream *substream, struct file *file, struct vm_area_struct *area);
diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h index 404d4b9ffe76..ebc17d5a3490 100644 --- a/include/uapi/sound/asound.h +++ b/include/uapi/sound/asound.h @@ -153,7 +153,7 @@ struct snd_hwdep_dsp_image { * * *****************************************************************************/
-#define SNDRV_PCM_VERSION SNDRV_PROTOCOL_VERSION(2, 0, 14) +#define SNDRV_PCM_VERSION SNDRV_PROTOCOL_VERSION(2, 0, 15)
typedef unsigned long snd_pcm_uframes_t; typedef signed long snd_pcm_sframes_t; @@ -576,6 +576,7 @@ enum { #define SNDRV_PCM_IOCTL_TSTAMP _IOW('A', 0x02, int) #define SNDRV_PCM_IOCTL_TTSTAMP _IOW('A', 0x03, int) #define SNDRV_PCM_IOCTL_USER_PVERSION _IOW('A', 0x04, int) +#define SNDRV_PCM_IOCTL_ANONYMOUS_DUP _IOWR('A', 0x05, int) #define SNDRV_PCM_IOCTL_HW_REFINE _IOWR('A', 0x10, struct snd_pcm_hw_params) #define SNDRV_PCM_IOCTL_HW_PARAMS _IOWR('A', 0x11, struct snd_pcm_hw_params) #define SNDRV_PCM_IOCTL_HW_FREE _IO('A', 0x12) diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c index d5b0d7ba83c4..2ed609b65c45 100644 --- a/sound/core/oss/pcm_oss.c +++ b/sound/core/oss/pcm_oss.c @@ -2420,7 +2420,7 @@ static int snd_pcm_oss_open_file(struct file *file, if (! (f_mode & FMODE_READ)) continue; } - err = snd_pcm_open_substream(pcm, idx, file, &substream); + err = snd_pcm_open_substream(pcm, idx, -1, file, &substream); if (err < 0) { snd_pcm_oss_release_file(pcm_oss_file); return err; diff --git a/sound/core/pcm.c b/sound/core/pcm.c index 4f45b3000347..af6f7fc3687b 100644 --- a/sound/core/pcm.c +++ b/sound/core/pcm.c @@ -918,15 +918,14 @@ static int snd_pcm_dev_free(struct snd_device *device) return snd_pcm_free(pcm); }
-int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream, - struct file *file, +int snd_pcm_attach_substream(struct snd_pcm *pcm, + int stream, int subdevice, struct file *file, struct snd_pcm_substream **rsubstream) { struct snd_pcm_str * pstr; struct snd_pcm_substream *substream; struct snd_pcm_runtime *runtime; struct snd_card *card; - int prefer_subdevice; size_t size;
if (snd_BUG_ON(!pcm || !rsubstream)) @@ -940,7 +939,6 @@ int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream, return -ENODEV;
card = pcm->card; - prefer_subdevice = snd_ctl_get_preferred_subdevice(card, SND_CTL_SUBDEV_PCM);
if (pcm->info_flags & SNDRV_PCM_INFO_HALF_DUPLEX) { int opposite = !stream; @@ -953,14 +951,14 @@ int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream, }
if (file->f_flags & O_APPEND) { - if (prefer_subdevice < 0) { + if (subdevice < 0) { if (pstr->substream_count > 1) return -EINVAL; /* must be unique */ substream = pstr->substream; } else { for (substream = pstr->substream; substream; substream = substream->next) - if (substream->number == prefer_subdevice) + if (substream->number == subdevice) break; } if (! substream) @@ -974,8 +972,7 @@ int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream,
for (substream = pstr->substream; substream; substream = substream->next) { if (!SUBSTREAM_BUSY(substream) && - (prefer_subdevice == -1 || - substream->number == prefer_subdevice)) + (subdevice == -1 || substream->number == subdevice)) break; } if (substream == NULL) diff --git a/sound/core/pcm_compat.c b/sound/core/pcm_compat.c index 946ab080ac00..22446cd574ee 100644 --- a/sound/core/pcm_compat.c +++ b/sound/core/pcm_compat.c @@ -675,6 +675,7 @@ static long snd_pcm_ioctl_compat(struct file *file, unsigned int cmd, unsigned l case SNDRV_PCM_IOCTL_TSTAMP: case SNDRV_PCM_IOCTL_TTSTAMP: case SNDRV_PCM_IOCTL_USER_PVERSION: + case SNDRV_PCM_IOCTL_ANONYMOUS_DUP: case SNDRV_PCM_IOCTL_HWSYNC: case SNDRV_PCM_IOCTL_PREPARE: case SNDRV_PCM_IOCTL_RESET: diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index 0bc4aa0ac9cf..bb14658e4482 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -37,6 +37,8 @@ #include <sound/minors.h> #include <linux/uio.h> #include <linux/delay.h> +#include <linux/anon_inodes.h> +#include <linux/syscalls.h>
#include "pcm_local.h"
@@ -2437,14 +2439,17 @@ void snd_pcm_release_substream(struct snd_pcm_substream *substream) } EXPORT_SYMBOL(snd_pcm_release_substream);
-int snd_pcm_open_substream(struct snd_pcm *pcm, int stream, +int snd_pcm_open_substream(struct snd_pcm *pcm, int stream, int subdevice, struct file *file, struct snd_pcm_substream **rsubstream) { struct snd_pcm_substream *substream; int err;
- err = snd_pcm_attach_substream(pcm, stream, file, &substream); + if (subdevice < 0 && pcm) + subdevice = snd_ctl_get_preferred_subdevice(pcm->card, SND_CTL_SUBDEV_PCM); + + err = snd_pcm_attach_substream(pcm, stream, subdevice, file, &substream); if (err < 0) return err; if (substream->ref_count > 1) { @@ -2480,13 +2485,14 @@ EXPORT_SYMBOL(snd_pcm_open_substream);
static int snd_pcm_open_file(struct file *file, struct snd_pcm *pcm, - int stream) + int stream, + int subdevice) { struct snd_pcm_file *pcm_file; struct snd_pcm_substream *substream; int err;
- err = snd_pcm_open_substream(pcm, stream, file, &substream); + err = snd_pcm_open_substream(pcm, stream, subdevice, file, &substream); if (err < 0) return err;
@@ -2551,7 +2557,7 @@ static int snd_pcm_open(struct file *file, struct snd_pcm *pcm, int stream) add_wait_queue(&pcm->open_wait, &wait); mutex_lock(&pcm->open_mutex); while (1) { - err = snd_pcm_open_file(file, pcm, stream); + err = snd_pcm_open_file(file, pcm, stream, -1); if (err >= 0) break; if (err == -EAGAIN) { @@ -2595,6 +2601,9 @@ static int snd_pcm_release(struct inode *inode, struct file *file) struct snd_pcm_file *pcm_file;
pcm_file = file->private_data; + /* a problem in the anonymous dup can hit the NULL pcm_file */ + if (pcm_file == NULL) + return 0; substream = pcm_file->substream; if (snd_BUG_ON(!substream)) return -ENXIO; @@ -2878,6 +2887,52 @@ static int snd_pcm_forward_ioctl(struct snd_pcm_substream *substream, return result < 0 ? result : 0; }
+static int snd_pcm_anonymous_dup(struct file *file, + struct snd_pcm_substream *substream, + int __user *arg) +{ + int fd, err, perm, flags; + struct file *nfile; + struct snd_pcm *pcm = substream->pcm; + + if (get_user(perm, arg)) + return -EFAULT; + if (perm < 0) + return -EPERM; + flags = file->f_flags & (O_ACCMODE | O_NONBLOCK); + flags |= O_APPEND | O_CLOEXEC; + fd = get_unused_fd_flags(flags); + if (fd < 0) + return fd; + nfile = anon_inode_getfile("snd-pcm", file->f_op, NULL, flags); + if (IS_ERR(nfile)) { + put_unused_fd(fd); + return PTR_ERR(nfile); + } + /* anon_inode_getfile() filters the O_APPEND flag out */ + nfile->f_flags |= O_APPEND; + fd_install(fd, nfile); + if (!try_module_get(pcm->card->module)) { + err = -EFAULT; + goto __error1; + } + err = snd_card_file_add(pcm->card, nfile); + if (err < 0) + goto __error2; + err = snd_pcm_open_file(nfile, substream->pcm, + substream->stream, substream->number); + if (err >= 0) { + put_user(fd, arg); + return 0; + } + snd_card_file_remove(pcm->card, nfile); + __error2: + module_put(pcm->card->module); + __error1: + ksys_close(fd); + return err; +} + static int snd_pcm_common_ioctl(struct file *file, struct snd_pcm_substream *substream, unsigned int cmd, void __user *arg) @@ -2906,6 +2961,8 @@ static int snd_pcm_common_ioctl(struct file *file, (unsigned int __user *)arg)) return -EFAULT; return 0; + case SNDRV_PCM_IOCTL_ANONYMOUS_DUP: + return snd_pcm_anonymous_dup(file, substream, (int __user *)arg); case SNDRV_PCM_IOCTL_HW_REFINE: return snd_pcm_hw_refine_user(substream, arg); case SNDRV_PCM_IOCTL_HW_PARAMS: