| Message ID | 22b21b3ddd5c11c43fcfb150a5cec30bd2cca8df.1650553693.git.qemu_oss@crudebyte.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | 9pfs: macOS host fixes | expand |
On Thu, 21 Apr 2022 17:07:46 +0200 Christian Schoenebeck <qemu_oss@crudebyte.com> wrote: > The 'rdev' field in 9p reponse 'Rgetattr' is of type dev_t, > which is actually a system dependant type and therefore both the > size and encoding of dev_t differ between macOS and Linux. > > So far we have sent 'rdev' to guest in host's dev_t format as-is, > which caused devices to appear with wrong device numbers on > guests running on macOS hosts, eventually leading to various > misbehaviours on guest in conjunction with device files. > > This patch fixes this issue by converting the device number from > host's dev_t format to Linux dev_t format. As 9p request > 'Tgettattr' is exclusive to protocol version 9p2000.L, it should > be fair to assume that 'rdev' field is assumed to be in Linux dev_t > format by client as well. > > Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com> > Link: https://lore.kernel.org/qemu-devel/20220421093056.5ab1e7ed@bahia/ > Reviewed-by: Greg Kurz <groug@kaod.org> > --- Reviewed-again-by: Greg Kurz <groug@kaod.org> > hw/9pfs/9p-util.h | 39 +++++++++++++++++++++++++++++++++++++++ > hw/9pfs/9p.c | 2 +- > 2 files changed, 40 insertions(+), 1 deletion(-) > > diff --git a/hw/9pfs/9p-util.h b/hw/9pfs/9p-util.h > index 97e681e167..2cc9a5dbfb 100644 > --- a/hw/9pfs/9p-util.h > +++ b/hw/9pfs/9p-util.h > @@ -19,6 +19,45 @@ > #define O_PATH_9P_UTIL 0 > #endif > > +#if !defined(CONFIG_LINUX) > + > +/* > + * Generates a Linux device number (a.k.a. dev_t) for given device major > + * and minor numbers. > + * > + * To be more precise: it generates a device number in glibc's format > + * (MMMM_Mmmm_mmmM_MMmm, 64 bits) actually, which is compatible with > + * Linux's format (mmmM_MMmm, 32 bits), as described in <bits/sysmacros.h>. > + */ > +static inline uint64_t makedev_dotl(uint32_t dev_major, uint32_t dev_minor) > +{ > + uint64_t dev; > + > + // from glibc sysmacros.h: > + dev = (((uint64_t) (dev_major & 0x00000fffu)) << 8); > + dev |= (((uint64_t) (dev_major & 0xfffff000u)) << 32); > + dev |= (((uint64_t) (dev_minor & 0x000000ffu)) << 0); > + dev |= (((uint64_t) (dev_minor & 0xffffff00u)) << 12); > + return dev; > +} > + > +#endif > + > +/* > + * Converts given device number from host's device number format to Linux > + * device number format. As both the size of type dev_t and encoding of > + * dev_t is system dependant, we have to convert them for Linux guests if > + * host is not running Linux. > + */ > +static inline uint64_t host_dev_to_dotl_dev(dev_t dev) > +{ > +#ifdef CONFIG_LINUX > + return dev; > +#else > + return makedev_dotl(major(dev), minor(dev)); > +#endif > +} > + > #ifdef CONFIG_DARWIN > #define qemu_fgetxattr(...) fgetxattr(__VA_ARGS__, 0, 0) > #define qemu_lgetxattr(...) getxattr(__VA_ARGS__, 0, XATTR_NOFOLLOW) > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c > index 225f31fc31..4a296a0b94 100644 > --- a/hw/9pfs/9p.c > +++ b/hw/9pfs/9p.c > @@ -1327,7 +1327,7 @@ static int stat_to_v9stat_dotl(V9fsPDU *pdu, const struct stat *stbuf, > v9lstat->st_nlink = stbuf->st_nlink; > v9lstat->st_uid = stbuf->st_uid; > v9lstat->st_gid = stbuf->st_gid; > - v9lstat->st_rdev = stbuf->st_rdev; > + v9lstat->st_rdev = host_dev_to_dotl_dev(stbuf->st_rdev); > v9lstat->st_size = stbuf->st_size; > v9lstat->st_blksize = stat_to_iounit(pdu, stbuf); > v9lstat->st_blocks = stbuf->st_blocks;
diff --git a/hw/9pfs/9p-util.h b/hw/9pfs/9p-util.h index 97e681e167..2cc9a5dbfb 100644 --- a/hw/9pfs/9p-util.h +++ b/hw/9pfs/9p-util.h @@ -19,6 +19,45 @@ #define O_PATH_9P_UTIL 0 #endif +#if !defined(CONFIG_LINUX) + +/* + * Generates a Linux device number (a.k.a. dev_t) for given device major + * and minor numbers. + * + * To be more precise: it generates a device number in glibc's format + * (MMMM_Mmmm_mmmM_MMmm, 64 bits) actually, which is compatible with + * Linux's format (mmmM_MMmm, 32 bits), as described in <bits/sysmacros.h>. + */ +static inline uint64_t makedev_dotl(uint32_t dev_major, uint32_t dev_minor) +{ + uint64_t dev; + + // from glibc sysmacros.h: + dev = (((uint64_t) (dev_major & 0x00000fffu)) << 8); + dev |= (((uint64_t) (dev_major & 0xfffff000u)) << 32); + dev |= (((uint64_t) (dev_minor & 0x000000ffu)) << 0); + dev |= (((uint64_t) (dev_minor & 0xffffff00u)) << 12); + return dev; +} + +#endif + +/* + * Converts given device number from host's device number format to Linux + * device number format. As both the size of type dev_t and encoding of + * dev_t is system dependant, we have to convert them for Linux guests if + * host is not running Linux. + */ +static inline uint64_t host_dev_to_dotl_dev(dev_t dev) +{ +#ifdef CONFIG_LINUX + return dev; +#else + return makedev_dotl(major(dev), minor(dev)); +#endif +} + #ifdef CONFIG_DARWIN #define qemu_fgetxattr(...) fgetxattr(__VA_ARGS__, 0, 0) #define qemu_lgetxattr(...) getxattr(__VA_ARGS__, 0, XATTR_NOFOLLOW) diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index 225f31fc31..4a296a0b94 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -1327,7 +1327,7 @@ static int stat_to_v9stat_dotl(V9fsPDU *pdu, const struct stat *stbuf, v9lstat->st_nlink = stbuf->st_nlink; v9lstat->st_uid = stbuf->st_uid; v9lstat->st_gid = stbuf->st_gid; - v9lstat->st_rdev = stbuf->st_rdev; + v9lstat->st_rdev = host_dev_to_dotl_dev(stbuf->st_rdev); v9lstat->st_size = stbuf->st_size; v9lstat->st_blksize = stat_to_iounit(pdu, stbuf); v9lstat->st_blocks = stbuf->st_blocks;