| Message ID | 20230624230950.2272-4-demi@invisiblethingslab.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Diskseq support in device-mapper | expand |
On 6/25/23 01:09, Demi Marie Obenour wrote: > Userspace can use this to avoid spamming udev with events that udev > should ignore. Well, does it also mean that udev will not create /dev/disk/by-* symlinks (as response to the change udev event followed by internal udev blkid scan)? If it is a private device, that is ok. But for a visible device I think that it breaks some assumptions in userspace (presence of symlinks mentioned above etc). So, what is the exact use for this patch? Milan > > Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com> > --- > drivers/md/dm-core.h | 2 + > drivers/md/dm-ioctl.c | 71 ++++++++++++++++++----------------- > drivers/md/dm.c | 5 ++- > include/linux/device-mapper.h | 2 +- > include/uapi/linux/dm-ioctl.h | 14 +++++-- > 5 files changed, 54 insertions(+), 40 deletions(-) > > diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h > index 0d93661f88d306e0d0aa3a1ac085880a8b63d9d6..5a4acdbf119f9b3f9a1c60de36d23f0658449701 100644 > --- a/drivers/md/dm-core.h > +++ b/drivers/md/dm-core.h > @@ -115,6 +115,8 @@ struct mapped_device { > > /* for blk-mq request-based DM support */ > bool init_tio_pdu:1; > + /* If set, do not emit any uevents. */ > + bool disable_uevents:1; > struct blk_mq_tag_set *tag_set; > > struct dm_stats stats; > diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c > index 7abaeec33f1884d4588e8563fb02e9ea1a6782c8..7eab9a8c77ff3286346a1c44581d3b6370a731eb 100644 > --- a/drivers/md/dm-ioctl.c > +++ b/drivers/md/dm-ioctl.c > @@ -821,6 +821,11 @@ static struct dm_table *dm_get_live_or_inactive_table(struct mapped_device *md, > dm_get_inactive_table(md, srcu_idx) : dm_get_live_table(md, srcu_idx); > } > > +static inline bool sloppy_checks(const struct dm_ioctl *param) > +{ > + return param->version[0] < DM_VERSION_MAJOR_STRICT; > +} > + > /* > * Fills in a dm_ioctl structure, ready for sending back to > * userland. > @@ -879,7 +884,7 @@ static void __dev_status(struct mapped_device *md, struct dm_ioctl *param) > dm_put_live_table(md, srcu_idx); > } > > - if (param->version[0] >= DM_VERSION_MAJOR_STRICT) > + if (!sloppy_checks(param)) > dm_set_diskseq(param, disk->diskseq); > } > > @@ -895,7 +900,7 @@ static int dev_create(struct file *filp, struct dm_ioctl *param, size_t param_si > if (param->flags & DM_PERSISTENT_DEV_FLAG) > m = MINOR(huge_decode_dev(param->dev)); > > - r = dm_create(m, &md); > + r = dm_create(m, &md, param->flags & DM_DISABLE_UEVENTS_FLAG); > if (r) > return r; > > @@ -1463,11 +1468,6 @@ static int next_target(struct dm_target_spec *last, uint32_t next, const char *e > return 0; > } > > -static inline bool sloppy_checks(const struct dm_ioctl *param) > -{ > - return param->version[0] < DM_VERSION_MAJOR_STRICT; > -} > - > static bool no_non_nul_after_nul(const char *untrusted_str, size_t size, > unsigned int cmd, const char *msg) > { > @@ -1939,64 +1939,67 @@ static int target_message(struct file *filp, struct dm_ioctl *param, size_t para > * Implementation of open/close/ioctl on the special char device. > *--------------------------------------------------------------- > */ > -static ioctl_fn lookup_ioctl(unsigned int cmd, int *ioctl_flags, uint32_t *supported_flags) > +static ioctl_fn lookup_ioctl(unsigned int cmd, bool strict, int *ioctl_flags, > + uint32_t *supported_flags) > { > static const struct { > int cmd; > int flags; > ioctl_fn fn; > uint32_t supported_flags; > + uint32_t strict_flags; > } _ioctls[] = { > /* Macro to make the structure initializers somewhat readable */ > -#define I(cmd, flags, fn, supported_flags) ((typeof(_ioctls[0])) { \ > +#define I(cmd, flags, fn, supported_flags, strict_flags) ((typeof(_ioctls[0])) { \ > (cmd), \ > (flags), \ > (fn), \ > /* > * Supported flags in sloppy mode must not include anything in DM_STRICT_ONLY_FLAGS. > - * Use BUILD_BUG_ON_ZERO to check for that. Currently there are no strict-only flags > - * defined. > + * Use BUILD_BUG_ON_ZERO to check for that. > */ \ > (supported_flags) | BUILD_BUG_ON_ZERO((supported_flags) & DM_STRICT_ONLY_FLAGS), \ > + (strict_flags) | (supported_flags) | \ > + BUILD_BUG_ON_ZERO((supported_flags) & (strict_flags)), \ > }) > - I(DM_VERSION_CMD, 0, NULL, 0), /* version is dealt with elsewhere */ > + I(DM_VERSION_CMD, 0, NULL, 0, 0), /* version is dealt with elsewhere */ > I(DM_REMOVE_ALL_CMD, IOCTL_FLAGS_NO_PARAMS | IOCTL_FLAGS_ISSUE_GLOBAL_EVENT, > - remove_all, DM_DEFERRED_REMOVE), > - I(DM_LIST_DEVICES_CMD, 0, list_devices, DM_UUID_FLAG), > + remove_all, DM_DEFERRED_REMOVE, 0), > + I(DM_LIST_DEVICES_CMD, 0, list_devices, DM_UUID_FLAG, 0), > I(DM_DEV_CREATE_CMD, IOCTL_FLAGS_NO_PARAMS | IOCTL_FLAGS_ISSUE_GLOBAL_EVENT, > - dev_create, DM_PERSISTENT_DEV_FLAG), > + dev_create, DM_PERSISTENT_DEV_FLAG, DM_DISABLE_UEVENTS_FLAG), > I(DM_DEV_REMOVE_CMD, IOCTL_FLAGS_NO_PARAMS | IOCTL_FLAGS_ISSUE_GLOBAL_EVENT, > - dev_remove, DM_DEFERRED_REMOVE), > + dev_remove, DM_DEFERRED_REMOVE, 0), > I(DM_DEV_RENAME_CMD, IOCTL_FLAGS_ISSUE_GLOBAL_EVENT, dev_rename, > - DM_QUERY_INACTIVE_TABLE_FLAG | DM_UUID_FLAG), > + DM_QUERY_INACTIVE_TABLE_FLAG | DM_UUID_FLAG, 0), > I(DM_DEV_SUSPEND_CMD, IOCTL_FLAGS_NO_PARAMS, dev_suspend, > - DM_QUERY_INACTIVE_TABLE_FLAG | DM_SUSPEND_FLAG | DM_SKIP_LOCKFS_FLAG | > - DM_NOFLUSH_FLAG), > + DM_QUERY_INACTIVE_TABLE_FLAG | DM_SUSPEND_FLAG | > + DM_SKIP_LOCKFS_FLAG | DM_NOFLUSH_FLAG, 0), > I(DM_DEV_STATUS_CMD, IOCTL_FLAGS_NO_PARAMS, dev_status, > - DM_QUERY_INACTIVE_TABLE_FLAG), > + DM_QUERY_INACTIVE_TABLE_FLAG, 0), > I(DM_DEV_WAIT_CMD, IOCTL_FLAGS_TAKES_EVENT_NR, dev_wait, > - DM_QUERY_INACTIVE_TABLE_FLAG | DM_STATUS_TABLE_FLAG | DM_NOFLUSH_FLAG), > - I(DM_TABLE_LOAD_CMD, 0, table_load, DM_QUERY_INACTIVE_TABLE_FLAG | > - DM_READONLY_FLAG), > + DM_QUERY_INACTIVE_TABLE_FLAG | DM_STATUS_TABLE_FLAG | DM_NOFLUSH_FLAG, 0), > + I(DM_TABLE_LOAD_CMD, 0, table_load, > + DM_QUERY_INACTIVE_TABLE_FLAG | DM_READONLY_FLAG, 0), > I(DM_TABLE_CLEAR_CMD, IOCTL_FLAGS_NO_PARAMS, table_clear, > - DM_QUERY_INACTIVE_TABLE_FLAG), > - I(DM_TABLE_DEPS_CMD, 0, table_deps, DM_QUERY_INACTIVE_TABLE_FLAG), > + DM_QUERY_INACTIVE_TABLE_FLAG, 0), > + I(DM_TABLE_DEPS_CMD, 0, table_deps, DM_QUERY_INACTIVE_TABLE_FLAG, 0), > I(DM_TABLE_STATUS_CMD, 0, table_status, > - DM_QUERY_INACTIVE_TABLE_FLAG | DM_STATUS_TABLE_FLAG | DM_NOFLUSH_FLAG), > + DM_QUERY_INACTIVE_TABLE_FLAG | DM_STATUS_TABLE_FLAG | DM_NOFLUSH_FLAG, 0), > > - I(DM_LIST_VERSIONS_CMD, 0, list_versions, 0), > + I(DM_LIST_VERSIONS_CMD, 0, list_versions, 0, 0), > > - I(DM_TARGET_MSG_CMD, 0, target_message, DM_QUERY_INACTIVE_TABLE_FLAG), > - I(DM_DEV_SET_GEOMETRY_CMD, 0, dev_set_geometry, 0), > - I(DM_DEV_ARM_POLL_CMD, IOCTL_FLAGS_NO_PARAMS, dev_arm_poll, 0), > - I(DM_GET_TARGET_VERSION_CMD, 0, get_target_version, 0), > + I(DM_TARGET_MSG_CMD, 0, target_message, DM_QUERY_INACTIVE_TABLE_FLAG, 0), > + I(DM_DEV_SET_GEOMETRY_CMD, 0, dev_set_geometry, 0, 0), > + I(DM_DEV_ARM_POLL_CMD, IOCTL_FLAGS_NO_PARAMS, dev_arm_poll, 0, 0), > + I(DM_GET_TARGET_VERSION_CMD, 0, get_target_version, 0, 0), > }; > > if (unlikely(cmd >= ARRAY_SIZE(_ioctls))) > return NULL; > > cmd = array_index_nospec(cmd, ARRAY_SIZE(_ioctls)); > - *supported_flags = _ioctls[cmd].supported_flags; > + *supported_flags = strict ? _ioctls[cmd].strict_flags : _ioctls[cmd].supported_flags; > *ioctl_flags = _ioctls[cmd].flags; > return _ioctls[cmd].fn; > } > @@ -2260,7 +2263,7 @@ static int ctl_ioctl(struct file *file, uint command, struct dm_ioctl __user *us > if (cmd == DM_VERSION_CMD) > return 0; > > - fn = lookup_ioctl(cmd, &ioctl_flags, &supported_flags); > + fn = lookup_ioctl(cmd, !sloppy_checks(¶m_kernel), &ioctl_flags, &supported_flags); > if (!fn) { > DMERR("dm_ctl_ioctl: unknown command 0x%x", command); > return -ENOTTY; > @@ -2480,7 +2483,7 @@ int __init dm_early_create(struct dm_ioctl *dmi, > m = MINOR(huge_decode_dev(dmi->dev)); > > /* alloc dm device */ > - r = dm_create(m, &md); > + r = dm_create(m, &md, false); > if (r) > return r; > > diff --git a/drivers/md/dm.c b/drivers/md/dm.c > index ea1671c39ba131ab2e49b93289d1094cda5cfb25..b7817b4aea52033afeeea9f2b93b9215de682e9c 100644 > --- a/drivers/md/dm.c > +++ b/drivers/md/dm.c > @@ -2281,13 +2281,14 @@ static struct dm_table *__unbind(struct mapped_device *md) > /* > * Constructor for a new device. > */ > -int dm_create(int minor, struct mapped_device **result) > +int dm_create(int minor, struct mapped_device **result, bool disable_uevents) > { > struct mapped_device *md; > > md = alloc_dev(minor); > if (!md) > return -ENXIO; > + md->disable_uevents = disable_uevents; > > dm_ima_reset_data(md); > > @@ -3005,6 +3006,8 @@ int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action, > char udev_cookie[DM_COOKIE_LENGTH]; > char *envp[3] = { NULL, NULL, NULL }; > char **envpp = envp; > + if (md->disable_uevents) > + return 0; > if (cookie) { > snprintf(udev_cookie, DM_COOKIE_LENGTH, "%s=%u", > DM_COOKIE_ENV_VAR_NAME, cookie); > diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h > index 69d0435c7ebb0d7b712e2b8bf32d9ba34c54e09e..2be940c2c6f42ed8e13b97ea8b07d0895566f3e2 100644 > --- a/include/linux/device-mapper.h > +++ b/include/linux/device-mapper.h > @@ -461,7 +461,7 @@ void dm_consume_args(struct dm_arg_set *as, unsigned int num_args); > * DM_ANY_MINOR chooses the next available minor number. > */ > #define DM_ANY_MINOR (-1) > -int dm_create(int minor, struct mapped_device **md); > +int dm_create(int minor, struct mapped_device **md, bool disable_uevents); > > /* > * Reference counting for md. > diff --git a/include/uapi/linux/dm-ioctl.h b/include/uapi/linux/dm-ioctl.h > index 1d33109aece2ff9854e752066baa96fdf7d85857..b338a4f9a299acda9430995d63fbb490e70c8cd8 100644 > --- a/include/uapi/linux/dm-ioctl.h > +++ b/include/uapi/linux/dm-ioctl.h > @@ -369,8 +369,16 @@ enum { > #define DM_BUFFER_FULL_FLAG (1 << 8) /* Out */ > > /* > - * This flag is now ignored if DM_VERSION_MAJOR is used, and causes > - * -EINVAL if DM_VERSION_MAJOR_STRICT is used. > + * This flag is only recognized when DM_VERSION_MAJOR_STRICT is used. > + * It tells the kernel to not generate any uevents for the newly-created > + * device. Using it outside of DM_DEV_CREATE results in -EINVAL. When > + * DM_VERSION_MAJOR is used this flag is ignored. > + */ > +#define DM_DISABLE_UEVENTS_FLAG (1 << 9) /* In */ > + > +/* > + * This flag is now ignored if DM_VERSION_MAJOR is used. When > + * DM_VERSION_MAJOR_STRICT is used it is an alias for DM_DISABLE_UEVENT_FLAG. > */ > #define DM_SKIP_BDGET_FLAG (1 << 9) /* In */ > > @@ -439,8 +447,6 @@ enum { > > /* > * If DM_VERSION_MAJOR is used, these flags are ignored by the kernel. > - * If DM_VERSION_MAJOR_STRICT is used, these flags are reserved and > - * must be zeroed. > */ > #define DM_STRICT_ONLY_FLAGS \ > (DM_ACTIVE_PRESENT_FLAG | DM_INACTIVE_PRESENT_FLAG | \ -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel
On Sun, Jun 25, 2023 at 03:25:38PM +0200, Milan Broz wrote: > On 6/25/23 01:09, Demi Marie Obenour wrote: > > Userspace can use this to avoid spamming udev with events that udev > > should ignore. > > Well, does it also mean that udev will not create /dev/disk/by-* symlinks > (as response to the change udev event followed by internal udev blkid scan)? In the use-case I have for this feature (block devices for Qubes VMs) the blkid scan is unwanted and there are udev rules to prevent this. > If it is a private device, that is ok. But for a visible device I think > that it breaks some assumptions in userspace (presence of symlinks mentioned > above etc). The devices I am considering are implementation details of a userspace process. Nobody else should be opening them. Ideally, no other userspace process would even know they exist, at least without mucking around in /proc or using ptrace. > So, what is the exact use for this patch? Ephemeral devices that are created, opened, marked for deferred removal, assigned to a Xen VM (needs another patch currently being worked on), and then closed. udev has no business scanning these devices, and indeed for it to scan them at all would be a security vulnerability since their contents are under guest control. There are udev rules to ignore these devices, but for udev to even process the event wastes CPU time and delays processing of other events that actually matter. The only symlink that possibly ought to be created is /dev/disk/by-diskseq and I can just do that myself.
On 6/25/23 18:02, Demi Marie Obenour wrote: > On Sun, Jun 25, 2023 at 03:25:38PM +0200, Milan Broz wrote: >> On 6/25/23 01:09, Demi Marie Obenour wrote: >>> Userspace can use this to avoid spamming udev with events that udev >>> should ignore. >> >> Well, does it also mean that udev will not create /dev/disk/by-* symlinks >> (as response to the change udev event followed by internal udev blkid scan)? > > In the use-case I have for this feature (block devices for Qubes VMs) > the blkid scan is unwanted and there are udev rules to prevent this. > >> If it is a private device, that is ok. But for a visible device I think >> that it breaks some assumptions in userspace (presence of symlinks mentioned >> above etc). > > The devices I am considering are implementation details of a userspace > process. Nobody else should be opening them. Ideally, no other > userspace process would even know they exist, at least without mucking > around in /proc or using ptrace. > >> So, what is the exact use for this patch? > > Ephemeral devices that are created, opened, marked for deferred removal, > assigned to a Xen VM (needs another patch currently being worked on), > and then closed. udev has no business scanning these devices, and > indeed for it to scan them at all would be a security vulnerability > since their contents are under guest control. There are udev rules to > ignore these devices, but for udev to even process the event wastes CPU > time and delays processing of other events that actually matter. The > only symlink that possibly ought to be created is /dev/disk/by-diskseq > and I can just do that myself. But this is not clear from the patch header. I guess you also need to disable udev inotify on close on write, which will trigger device scan too. BTW we use exactly this scenario in cryptsetup for years with existing flags (DM_UDEV_DISABLE_SUBSYSTEM_RULES_FLAG | DM_UDEV_DISABLE_DISK_RULES_FLAG DM_UDEV_DISABLE_OTHER_RULES_FLAG) - just rules are ignored while uevent is still sent. Anyway, not sure we need another way to disable it; I just asked do you need it. Milan -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel
On Sun, Jun 25, 2023 at 06:33:33PM +0200, Milan Broz wrote: > On 6/25/23 18:02, Demi Marie Obenour wrote: > > On Sun, Jun 25, 2023 at 03:25:38PM +0200, Milan Broz wrote: > > > On 6/25/23 01:09, Demi Marie Obenour wrote: > > > > Userspace can use this to avoid spamming udev with events that udev > > > > should ignore. > > > > > > Well, does it also mean that udev will not create /dev/disk/by-* symlinks > > > (as response to the change udev event followed by internal udev blkid scan)? > > > > In the use-case I have for this feature (block devices for Qubes VMs) > > the blkid scan is unwanted and there are udev rules to prevent this. > > > > > If it is a private device, that is ok. But for a visible device I think > > > that it breaks some assumptions in userspace (presence of symlinks mentioned > > > above etc). > > > > The devices I am considering are implementation details of a userspace > > process. Nobody else should be opening them. Ideally, no other > > userspace process would even know they exist, at least without mucking > > around in /proc or using ptrace. > > > > > So, what is the exact use for this patch? > > > > Ephemeral devices that are created, opened, marked for deferred removal, > > assigned to a Xen VM (needs another patch currently being worked on), > > and then closed. udev has no business scanning these devices, and > > indeed for it to scan them at all would be a security vulnerability > > since their contents are under guest control. There are udev rules to > > ignore these devices, but for udev to even process the event wastes CPU > > time and delays processing of other events that actually matter. The > > only symlink that possibly ought to be created is /dev/disk/by-diskseq > > and I can just do that myself. > But this is not clear from the patch header. I guess you also need > to disable udev inotify on close on write, which will trigger device scan too. > > BTW we use exactly this scenario in cryptsetup for years with existing flags > (DM_UDEV_DISABLE_SUBSYSTEM_RULES_FLAG | DM_UDEV_DISABLE_DISK_RULES_FLAG > DM_UDEV_DISABLE_OTHER_RULES_FLAG) - just rules are ignored while uevent is still > sent. > Anyway, not sure we need another way to disable it; I just asked do you need it. How can one set these flags using the raw kernel ioctls? The code I am working on does not use libdevmapper at all and just uses the kernel API directly.
On 6/25/23 18:43, Demi Marie Obenour wrote: > On Sun, Jun 25, 2023 at 06:33:33PM +0200, Milan Broz wrote: ... >> BTW we use exactly this scenario in cryptsetup for years with existing flags >> (DM_UDEV_DISABLE_SUBSYSTEM_RULES_FLAG | DM_UDEV_DISABLE_DISK_RULES_FLAG >> DM_UDEV_DISABLE_OTHER_RULES_FLAG) - just rules are ignored while uevent is still >> sent. >> Anyway, not sure we need another way to disable it; I just asked do you need it. > > How can one set these flags using the raw kernel ioctls? The code I am > working on does not use libdevmapper at all and just uses the kernel API > directly. IIRC you need to set cookie (kernel DM_COOKIE env), then default udev dm.rules decode the flags from it. (It is libdevmapper internal magic for me, the design is kind of complicated, but works.) Better ask on LVM list (but the udev DM rules are pretty well inline documented). Milan -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel
diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h index 0d93661f88d306e0d0aa3a1ac085880a8b63d9d6..5a4acdbf119f9b3f9a1c60de36d23f0658449701 100644 --- a/drivers/md/dm-core.h +++ b/drivers/md/dm-core.h @@ -115,6 +115,8 @@ struct mapped_device { /* for blk-mq request-based DM support */ bool init_tio_pdu:1; + /* If set, do not emit any uevents. */ + bool disable_uevents:1; struct blk_mq_tag_set *tag_set; struct dm_stats stats; diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index 7abaeec33f1884d4588e8563fb02e9ea1a6782c8..7eab9a8c77ff3286346a1c44581d3b6370a731eb 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -821,6 +821,11 @@ static struct dm_table *dm_get_live_or_inactive_table(struct mapped_device *md, dm_get_inactive_table(md, srcu_idx) : dm_get_live_table(md, srcu_idx); } +static inline bool sloppy_checks(const struct dm_ioctl *param) +{ + return param->version[0] < DM_VERSION_MAJOR_STRICT; +} + /* * Fills in a dm_ioctl structure, ready for sending back to * userland. @@ -879,7 +884,7 @@ static void __dev_status(struct mapped_device *md, struct dm_ioctl *param) dm_put_live_table(md, srcu_idx); } - if (param->version[0] >= DM_VERSION_MAJOR_STRICT) + if (!sloppy_checks(param)) dm_set_diskseq(param, disk->diskseq); } @@ -895,7 +900,7 @@ static int dev_create(struct file *filp, struct dm_ioctl *param, size_t param_si if (param->flags & DM_PERSISTENT_DEV_FLAG) m = MINOR(huge_decode_dev(param->dev)); - r = dm_create(m, &md); + r = dm_create(m, &md, param->flags & DM_DISABLE_UEVENTS_FLAG); if (r) return r; @@ -1463,11 +1468,6 @@ static int next_target(struct dm_target_spec *last, uint32_t next, const char *e return 0; } -static inline bool sloppy_checks(const struct dm_ioctl *param) -{ - return param->version[0] < DM_VERSION_MAJOR_STRICT; -} - static bool no_non_nul_after_nul(const char *untrusted_str, size_t size, unsigned int cmd, const char *msg) { @@ -1939,64 +1939,67 @@ static int target_message(struct file *filp, struct dm_ioctl *param, size_t para * Implementation of open/close/ioctl on the special char device. *--------------------------------------------------------------- */ -static ioctl_fn lookup_ioctl(unsigned int cmd, int *ioctl_flags, uint32_t *supported_flags) +static ioctl_fn lookup_ioctl(unsigned int cmd, bool strict, int *ioctl_flags, + uint32_t *supported_flags) { static const struct { int cmd; int flags; ioctl_fn fn; uint32_t supported_flags; + uint32_t strict_flags; } _ioctls[] = { /* Macro to make the structure initializers somewhat readable */ -#define I(cmd, flags, fn, supported_flags) ((typeof(_ioctls[0])) { \ +#define I(cmd, flags, fn, supported_flags, strict_flags) ((typeof(_ioctls[0])) { \ (cmd), \ (flags), \ (fn), \ /* * Supported flags in sloppy mode must not include anything in DM_STRICT_ONLY_FLAGS. - * Use BUILD_BUG_ON_ZERO to check for that. Currently there are no strict-only flags - * defined. + * Use BUILD_BUG_ON_ZERO to check for that. */ \ (supported_flags) | BUILD_BUG_ON_ZERO((supported_flags) & DM_STRICT_ONLY_FLAGS), \ + (strict_flags) | (supported_flags) | \ + BUILD_BUG_ON_ZERO((supported_flags) & (strict_flags)), \ }) - I(DM_VERSION_CMD, 0, NULL, 0), /* version is dealt with elsewhere */ + I(DM_VERSION_CMD, 0, NULL, 0, 0), /* version is dealt with elsewhere */ I(DM_REMOVE_ALL_CMD, IOCTL_FLAGS_NO_PARAMS | IOCTL_FLAGS_ISSUE_GLOBAL_EVENT, - remove_all, DM_DEFERRED_REMOVE), - I(DM_LIST_DEVICES_CMD, 0, list_devices, DM_UUID_FLAG), + remove_all, DM_DEFERRED_REMOVE, 0), + I(DM_LIST_DEVICES_CMD, 0, list_devices, DM_UUID_FLAG, 0), I(DM_DEV_CREATE_CMD, IOCTL_FLAGS_NO_PARAMS | IOCTL_FLAGS_ISSUE_GLOBAL_EVENT, - dev_create, DM_PERSISTENT_DEV_FLAG), + dev_create, DM_PERSISTENT_DEV_FLAG, DM_DISABLE_UEVENTS_FLAG), I(DM_DEV_REMOVE_CMD, IOCTL_FLAGS_NO_PARAMS | IOCTL_FLAGS_ISSUE_GLOBAL_EVENT, - dev_remove, DM_DEFERRED_REMOVE), + dev_remove, DM_DEFERRED_REMOVE, 0), I(DM_DEV_RENAME_CMD, IOCTL_FLAGS_ISSUE_GLOBAL_EVENT, dev_rename, - DM_QUERY_INACTIVE_TABLE_FLAG | DM_UUID_FLAG), + DM_QUERY_INACTIVE_TABLE_FLAG | DM_UUID_FLAG, 0), I(DM_DEV_SUSPEND_CMD, IOCTL_FLAGS_NO_PARAMS, dev_suspend, - DM_QUERY_INACTIVE_TABLE_FLAG | DM_SUSPEND_FLAG | DM_SKIP_LOCKFS_FLAG | - DM_NOFLUSH_FLAG), + DM_QUERY_INACTIVE_TABLE_FLAG | DM_SUSPEND_FLAG | + DM_SKIP_LOCKFS_FLAG | DM_NOFLUSH_FLAG, 0), I(DM_DEV_STATUS_CMD, IOCTL_FLAGS_NO_PARAMS, dev_status, - DM_QUERY_INACTIVE_TABLE_FLAG), + DM_QUERY_INACTIVE_TABLE_FLAG, 0), I(DM_DEV_WAIT_CMD, IOCTL_FLAGS_TAKES_EVENT_NR, dev_wait, - DM_QUERY_INACTIVE_TABLE_FLAG | DM_STATUS_TABLE_FLAG | DM_NOFLUSH_FLAG), - I(DM_TABLE_LOAD_CMD, 0, table_load, DM_QUERY_INACTIVE_TABLE_FLAG | - DM_READONLY_FLAG), + DM_QUERY_INACTIVE_TABLE_FLAG | DM_STATUS_TABLE_FLAG | DM_NOFLUSH_FLAG, 0), + I(DM_TABLE_LOAD_CMD, 0, table_load, + DM_QUERY_INACTIVE_TABLE_FLAG | DM_READONLY_FLAG, 0), I(DM_TABLE_CLEAR_CMD, IOCTL_FLAGS_NO_PARAMS, table_clear, - DM_QUERY_INACTIVE_TABLE_FLAG), - I(DM_TABLE_DEPS_CMD, 0, table_deps, DM_QUERY_INACTIVE_TABLE_FLAG), + DM_QUERY_INACTIVE_TABLE_FLAG, 0), + I(DM_TABLE_DEPS_CMD, 0, table_deps, DM_QUERY_INACTIVE_TABLE_FLAG, 0), I(DM_TABLE_STATUS_CMD, 0, table_status, - DM_QUERY_INACTIVE_TABLE_FLAG | DM_STATUS_TABLE_FLAG | DM_NOFLUSH_FLAG), + DM_QUERY_INACTIVE_TABLE_FLAG | DM_STATUS_TABLE_FLAG | DM_NOFLUSH_FLAG, 0), - I(DM_LIST_VERSIONS_CMD, 0, list_versions, 0), + I(DM_LIST_VERSIONS_CMD, 0, list_versions, 0, 0), - I(DM_TARGET_MSG_CMD, 0, target_message, DM_QUERY_INACTIVE_TABLE_FLAG), - I(DM_DEV_SET_GEOMETRY_CMD, 0, dev_set_geometry, 0), - I(DM_DEV_ARM_POLL_CMD, IOCTL_FLAGS_NO_PARAMS, dev_arm_poll, 0), - I(DM_GET_TARGET_VERSION_CMD, 0, get_target_version, 0), + I(DM_TARGET_MSG_CMD, 0, target_message, DM_QUERY_INACTIVE_TABLE_FLAG, 0), + I(DM_DEV_SET_GEOMETRY_CMD, 0, dev_set_geometry, 0, 0), + I(DM_DEV_ARM_POLL_CMD, IOCTL_FLAGS_NO_PARAMS, dev_arm_poll, 0, 0), + I(DM_GET_TARGET_VERSION_CMD, 0, get_target_version, 0, 0), }; if (unlikely(cmd >= ARRAY_SIZE(_ioctls))) return NULL; cmd = array_index_nospec(cmd, ARRAY_SIZE(_ioctls)); - *supported_flags = _ioctls[cmd].supported_flags; + *supported_flags = strict ? _ioctls[cmd].strict_flags : _ioctls[cmd].supported_flags; *ioctl_flags = _ioctls[cmd].flags; return _ioctls[cmd].fn; } @@ -2260,7 +2263,7 @@ static int ctl_ioctl(struct file *file, uint command, struct dm_ioctl __user *us if (cmd == DM_VERSION_CMD) return 0; - fn = lookup_ioctl(cmd, &ioctl_flags, &supported_flags); + fn = lookup_ioctl(cmd, !sloppy_checks(¶m_kernel), &ioctl_flags, &supported_flags); if (!fn) { DMERR("dm_ctl_ioctl: unknown command 0x%x", command); return -ENOTTY; @@ -2480,7 +2483,7 @@ int __init dm_early_create(struct dm_ioctl *dmi, m = MINOR(huge_decode_dev(dmi->dev)); /* alloc dm device */ - r = dm_create(m, &md); + r = dm_create(m, &md, false); if (r) return r; diff --git a/drivers/md/dm.c b/drivers/md/dm.c index ea1671c39ba131ab2e49b93289d1094cda5cfb25..b7817b4aea52033afeeea9f2b93b9215de682e9c 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -2281,13 +2281,14 @@ static struct dm_table *__unbind(struct mapped_device *md) /* * Constructor for a new device. */ -int dm_create(int minor, struct mapped_device **result) +int dm_create(int minor, struct mapped_device **result, bool disable_uevents) { struct mapped_device *md; md = alloc_dev(minor); if (!md) return -ENXIO; + md->disable_uevents = disable_uevents; dm_ima_reset_data(md); @@ -3005,6 +3006,8 @@ int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action, char udev_cookie[DM_COOKIE_LENGTH]; char *envp[3] = { NULL, NULL, NULL }; char **envpp = envp; + if (md->disable_uevents) + return 0; if (cookie) { snprintf(udev_cookie, DM_COOKIE_LENGTH, "%s=%u", DM_COOKIE_ENV_VAR_NAME, cookie); diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index 69d0435c7ebb0d7b712e2b8bf32d9ba34c54e09e..2be940c2c6f42ed8e13b97ea8b07d0895566f3e2 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -461,7 +461,7 @@ void dm_consume_args(struct dm_arg_set *as, unsigned int num_args); * DM_ANY_MINOR chooses the next available minor number. */ #define DM_ANY_MINOR (-1) -int dm_create(int minor, struct mapped_device **md); +int dm_create(int minor, struct mapped_device **md, bool disable_uevents); /* * Reference counting for md. diff --git a/include/uapi/linux/dm-ioctl.h b/include/uapi/linux/dm-ioctl.h index 1d33109aece2ff9854e752066baa96fdf7d85857..b338a4f9a299acda9430995d63fbb490e70c8cd8 100644 --- a/include/uapi/linux/dm-ioctl.h +++ b/include/uapi/linux/dm-ioctl.h @@ -369,8 +369,16 @@ enum { #define DM_BUFFER_FULL_FLAG (1 << 8) /* Out */ /* - * This flag is now ignored if DM_VERSION_MAJOR is used, and causes - * -EINVAL if DM_VERSION_MAJOR_STRICT is used. + * This flag is only recognized when DM_VERSION_MAJOR_STRICT is used. + * It tells the kernel to not generate any uevents for the newly-created + * device. Using it outside of DM_DEV_CREATE results in -EINVAL. When + * DM_VERSION_MAJOR is used this flag is ignored. + */ +#define DM_DISABLE_UEVENTS_FLAG (1 << 9) /* In */ + +/* + * This flag is now ignored if DM_VERSION_MAJOR is used. When + * DM_VERSION_MAJOR_STRICT is used it is an alias for DM_DISABLE_UEVENT_FLAG. */ #define DM_SKIP_BDGET_FLAG (1 << 9) /* In */ @@ -439,8 +447,6 @@ enum { /* * If DM_VERSION_MAJOR is used, these flags are ignored by the kernel. - * If DM_VERSION_MAJOR_STRICT is used, these flags are reserved and - * must be zeroed. */ #define DM_STRICT_ONLY_FLAGS \ (DM_ACTIVE_PRESENT_FLAG | DM_INACTIVE_PRESENT_FLAG | \
Userspace can use this to avoid spamming udev with events that udev should ignore. Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com> --- drivers/md/dm-core.h | 2 + drivers/md/dm-ioctl.c | 71 ++++++++++++++++++----------------- drivers/md/dm.c | 5 ++- include/linux/device-mapper.h | 2 +- include/uapi/linux/dm-ioctl.h | 14 +++++-- 5 files changed, 54 insertions(+), 40 deletions(-)