| Message ID | 20220701201123.183468-1-bongiojp@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] Add ioctls to get/set the ext4 superblock uuid. | expand |
On Fri, Jul 01, 2022 at 01:11:23PM -0700, Jeremy Bongio wrote: > This fixes a race between changing the ext4 superblock uuid and operations > like mounting, resizing, changing features, etc. > > Reviewed-by: Theodore Ts'o <tytso@mit.edu> > Signed-off-by: Jeremy Bongio <bongiojp@gmail.com> > --- > fs/ext4/ext4.h | 13 ++++++++ > fs/ext4/ioctl.c | 83 +++++++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 96 insertions(+) > > diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h > index 75b8d81b2469..0cf960cb591e 100644 > --- a/fs/ext4/ext4.h > +++ b/fs/ext4/ext4.h > @@ -724,6 +724,8 @@ enum { > #define EXT4_IOC_GETSTATE _IOW('f', 41, __u32) > #define EXT4_IOC_GET_ES_CACHE _IOWR('f', 42, struct fiemap) > #define EXT4_IOC_CHECKPOINT _IOW('f', 43, __u32) > +#define EXT4_IOC_GETFSUUID _IOR('f', 44, struct fsuuid) > +#define EXT4_IOC_SETFSUUID _IOW('f', 44, struct fsuuid) > > #define EXT4_IOC_SHUTDOWN _IOR ('X', 125, __u32) > > @@ -753,6 +755,17 @@ enum { > EXT4_IOC_CHECKPOINT_FLAG_ZEROOUT | \ > EXT4_IOC_CHECKPOINT_FLAG_DRY_RUN) > > +/* > + * Structure for EXT4_IOC_GETFSUUID/EXT4_IOC_SETFSUUID > + */ > +struct fsuuid { > + __u32 fu_len; > + __u32 fu_flags; > + __u8 __user fu_uuid[]; __user is unnecessary here -- it applies to pointers, not to struct members. > +}; > + > +#define EXT4_IOC_SETFSUUID_FLAG_BLOCKING 0x1 What does this do? (Better yet, can you please write a manpage describing these new ioctls?) > + > #if defined(__KERNEL__) && defined(CONFIG_COMPAT) > /* > * ioctl commands in 32 bit emulation > diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c > index cb01c1da0f9d..75069afc16ae 100644 > --- a/fs/ext4/ioctl.c > +++ b/fs/ext4/ioctl.c > @@ -20,6 +20,7 @@ > #include <linux/delay.h> > #include <linux/iversion.h> > #include <linux/fileattr.h> > +#include <linux/uuid.h> > #include "ext4_jbd2.h" > #include "ext4.h" > #include <linux/fsmap.h> > @@ -41,6 +42,15 @@ static void ext4_sb_setlabel(struct ext4_super_block *es, const void *arg) > memcpy(es->s_volume_name, (char *)arg, EXT4_LABEL_MAX); > } > > +/* > + * Superblock modification callback function for changing file system > + * UUID. > + */ > +static void ext4_sb_setuuid(struct ext4_super_block *es, const void *arg) > +{ > + memcpy(es->s_uuid, (__u8 *)arg, UUID_SIZE); > +} > + > static > int ext4_update_primary_sb(struct super_block *sb, handle_t *handle, > ext4_update_sb_callback func, > @@ -1131,6 +1141,73 @@ static int ext4_ioctl_getlabel(struct ext4_sb_info *sbi, char __user *user_label > return 0; > } > > +static int ext4_ioctl_getuuid(struct ext4_sb_info *sbi, > + struct fsuuid __user *ufsuuid) > +{ > + int ret = 0; > + __u8 uuid[UUID_SIZE]; Save some stack space and copy sbi->s_es->s_uuid into fsuuid.fu_uuid, and then copy_to_user from the kernel stack object out to userspace's object. > + struct fsuuid fsuuid; > + > + if (copy_from_user(&fsuuid, ufsuuid, sizeof(fsuuid))) > + return -EFAULT; > + > + if (fsuuid.fu_len != UUID_SIZE) > + return -EINVAL; This function needs to check that fsuuid.fu_flags doesn't contain any unknown bitflags. > + > + lock_buffer(sbi->s_sbh); > + memcpy(uuid, sbi->s_es->s_uuid, UUID_SIZE); > + unlock_buffer(sbi->s_sbh); > + > + if (copy_to_user(&ufsuuid->fu_uuid[0], uuid, UUID_SIZE)) > + ret = -EFAULT; > + return ret; if (copy_to_user(...)) return -EFAULT; return 0; ? > +} > + > +static int ext4_ioctl_setuuid(struct file *filp, > + const struct fsuuid __user *ufsuuid) > +{ > + int ret = 0; > + struct super_block *sb = file_inode(filp)->i_sb; > + struct fsuuid fsuuid; > + __u8 uuid[UUID_SIZE]; > + > + if (!capable(CAP_SYS_ADMIN)) > + return -EPERM; > + > + /* > + * If any checksums (group descriptors or metadata) are being used > + * then the checksum seed feature is required to change the UUID. > + */ > + if (((ext4_has_feature_gdt_csum(sb) || ext4_has_metadata_csum(sb)) > + && !ext4_has_feature_csum_seed(sb)) > + || ext4_has_feature_stable_inodes(sb)) > + return -EOPNOTSUPP; > + > + if (copy_from_user(&fsuuid, ufsuuid, sizeof(fsuuid))) > + return -EFAULT; > + > + if (fsuuid.fu_len != UUID_SIZE) > + return -EINVAL; This function needs to check that fsuuid.fu_flags doesn't contain any unknown bits. > + > + if (copy_from_user(uuid, &ufsuuid->fu_uuid[0], UUID_SIZE)) > + return -EFAULT; > + > + ret = mnt_want_write_file(filp); > + if (ret) > + return ret; > + > + do { > + if (ret == -EBUSY) > + msleep(1000); > + ret = ext4_update_superblocks_fn(sb, ext4_sb_setuuid, &uuid); > + } while (ret == -EBUSY && > + fsuuid.fu_flags & EXT4_IOC_SETFSUUID_FLAG_BLOCKING); So... I guess by default, userspace gets NOWAIT mode? That's a little strange, usually kernel convention is blocking mode by default, with nowait selectable via function flags. Also, what's the intended use case here? Why would we want to set a uuid but only if the superblock(s) aren't busy? --D > + > + mnt_drop_write_file(filp); > + > + return ret; > +} > + > static long __ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) > { > struct inode *inode = file_inode(filp); > @@ -1509,6 +1586,10 @@ static long __ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) > return ext4_ioctl_setlabel(filp, > (const void __user *)arg); > > + case EXT4_IOC_GETFSUUID: > + return ext4_ioctl_getuuid(EXT4_SB(sb), (void __user *)arg); > + case EXT4_IOC_SETFSUUID: > + return ext4_ioctl_setuuid(filp, (const void __user *)arg); > default: > return -ENOTTY; > } > @@ -1586,6 +1667,8 @@ long ext4_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) > case EXT4_IOC_CHECKPOINT: > case FS_IOC_GETFSLABEL: > case FS_IOC_SETFSLABEL: > + case EXT4_IOC_GETFSUUID: > + case EXT4_IOC_SETFSUUID: > break; > default: > return -ENOIOCTLCMD; > -- > 2.37.0.rc0.161.g10f37bed90-goog >
On Tue, Jul 5, 2022 at 10:07 AM Darrick J. Wong <djwong@kernel.org> wrote: > > On Fri, Jul 01, 2022 at 01:11:23PM -0700, Jeremy Bongio wrote: > > This fixes a race between changing the ext4 superblock uuid and operations > > like mounting, resizing, changing features, etc. > > > > Reviewed-by: Theodore Ts'o <tytso@mit.edu> > > Signed-off-by: Jeremy Bongio <bongiojp@gmail.com> > > --- > > fs/ext4/ext4.h | 13 ++++++++ > > fs/ext4/ioctl.c | 83 +++++++++++++++++++++++++++++++++++++++++++++++++ > > 2 files changed, 96 insertions(+) > > > > diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h > > index 75b8d81b2469..0cf960cb591e 100644 > > --- a/fs/ext4/ext4.h > > +++ b/fs/ext4/ext4.h > > @@ -724,6 +724,8 @@ enum { > > #define EXT4_IOC_GETSTATE _IOW('f', 41, __u32) > > #define EXT4_IOC_GET_ES_CACHE _IOWR('f', 42, struct fiemap) > > #define EXT4_IOC_CHECKPOINT _IOW('f', 43, __u32) > > +#define EXT4_IOC_GETFSUUID _IOR('f', 44, struct fsuuid) > > +#define EXT4_IOC_SETFSUUID _IOW('f', 44, struct fsuuid) > > > > #define EXT4_IOC_SHUTDOWN _IOR ('X', 125, __u32) > > > > @@ -753,6 +755,17 @@ enum { > > EXT4_IOC_CHECKPOINT_FLAG_ZEROOUT | \ > > EXT4_IOC_CHECKPOINT_FLAG_DRY_RUN) > > > > +/* > > + * Structure for EXT4_IOC_GETFSUUID/EXT4_IOC_SETFSUUID > > + */ > > +struct fsuuid { > > + __u32 fu_len; > > + __u32 fu_flags; > > + __u8 __user fu_uuid[]; > > __user is unnecessary here -- it applies to pointers, not to struct > members. > > > +}; > > + > > +#define EXT4_IOC_SETFSUUID_FLAG_BLOCKING 0x1 > > What does this do? > > (Better yet, can you please write a manpage describing these new > ioctls?) Good idea. I'll write a manpage as if it were being converted to a general ioctl and not specific to ext4. > > > + > > #if defined(__KERNEL__) && defined(CONFIG_COMPAT) > > /* > > * ioctl commands in 32 bit emulation > > diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c > > index cb01c1da0f9d..75069afc16ae 100644 > > --- a/fs/ext4/ioctl.c > > +++ b/fs/ext4/ioctl.c > > @@ -20,6 +20,7 @@ > > #include <linux/delay.h> > > #include <linux/iversion.h> > > #include <linux/fileattr.h> > > +#include <linux/uuid.h> > > #include "ext4_jbd2.h" > > #include "ext4.h" > > #include <linux/fsmap.h> > > @@ -41,6 +42,15 @@ static void ext4_sb_setlabel(struct ext4_super_block *es, const void *arg) > > memcpy(es->s_volume_name, (char *)arg, EXT4_LABEL_MAX); > > } > > > > +/* > > + * Superblock modification callback function for changing file system > > + * UUID. > > + */ > > +static void ext4_sb_setuuid(struct ext4_super_block *es, const void *arg) > > +{ > > + memcpy(es->s_uuid, (__u8 *)arg, UUID_SIZE); > > +} > > + > > static > > int ext4_update_primary_sb(struct super_block *sb, handle_t *handle, > > ext4_update_sb_callback func, > > @@ -1131,6 +1141,73 @@ static int ext4_ioctl_getlabel(struct ext4_sb_info *sbi, char __user *user_label > > return 0; > > } > > > > +static int ext4_ioctl_getuuid(struct ext4_sb_info *sbi, > > + struct fsuuid __user *ufsuuid) > > +{ > > + int ret = 0; > > + __u8 uuid[UUID_SIZE]; > > Save some stack space and copy sbi->s_es->s_uuid into fsuuid.fu_uuid, > and then copy_to_user from the kernel stack object out to userspace's > object. I can't copy sbi->s_es->s_uuid into fsuuid.fu_uuid since fu_uuid is a VLA (size 0 array). Are you suggesting I copy_to_user() from sbi->s_es->s_uuid into ufsuuid within the locked region? > > > + struct fsuuid fsuuid; > > + > > + if (copy_from_user(&fsuuid, ufsuuid, sizeof(fsuuid))) > > + return -EFAULT; > > + > > + if (fsuuid.fu_len != UUID_SIZE) > > + return -EINVAL; > > This function needs to check that fsuuid.fu_flags doesn't contain any > unknown bitflags. > > > + > > + lock_buffer(sbi->s_sbh); > > + memcpy(uuid, sbi->s_es->s_uuid, UUID_SIZE); > > + unlock_buffer(sbi->s_sbh); > > + > > + if (copy_to_user(&ufsuuid->fu_uuid[0], uuid, UUID_SIZE)) > > + ret = -EFAULT; > > + return ret; > > if (copy_to_user(...)) > return -EFAULT; > > return 0; > > ? > > > +} > > + > > +static int ext4_ioctl_setuuid(struct file *filp, > > + const struct fsuuid __user *ufsuuid) > > +{ > > + int ret = 0; > > + struct super_block *sb = file_inode(filp)->i_sb; > > + struct fsuuid fsuuid; > > + __u8 uuid[UUID_SIZE]; > > + > > + if (!capable(CAP_SYS_ADMIN)) > > + return -EPERM; > > + > > + /* > > + * If any checksums (group descriptors or metadata) are being used > > + * then the checksum seed feature is required to change the UUID. > > + */ > > + if (((ext4_has_feature_gdt_csum(sb) || ext4_has_metadata_csum(sb)) > > + && !ext4_has_feature_csum_seed(sb)) > > + || ext4_has_feature_stable_inodes(sb)) > > + return -EOPNOTSUPP; > > + > > + if (copy_from_user(&fsuuid, ufsuuid, sizeof(fsuuid))) > > + return -EFAULT; > > + > > + if (fsuuid.fu_len != UUID_SIZE) > > + return -EINVAL; > > This function needs to check that fsuuid.fu_flags doesn't contain any > unknown bits. > > > + > > + if (copy_from_user(uuid, &ufsuuid->fu_uuid[0], UUID_SIZE)) > > + return -EFAULT; > > + > > + ret = mnt_want_write_file(filp); > > + if (ret) > > + return ret; > > + > > + do { > > + if (ret == -EBUSY) > > + msleep(1000); > > + ret = ext4_update_superblocks_fn(sb, ext4_sb_setuuid, &uuid); > > + } while (ret == -EBUSY && > > + fsuuid.fu_flags & EXT4_IOC_SETFSUUID_FLAG_BLOCKING); > > So... I guess by default, userspace gets NOWAIT mode? That's a little > strange, usually kernel convention is blocking mode by default, with > nowait selectable via function flags. > > Also, what's the intended use case here? Why would we want to set a > uuid but only if the superblock(s) aren't busy? When an ext4 filesystem is being resized, which could potentially take a long time, ext4_update_superblocks_fn() will return -EBUSY. In that case we can either sleep and retry, or return EBUSY to userspace. However, for my use case, I only care about the blocking case. I'll remove the flag since the default mode will be blocking. > > --D > > > + > > + mnt_drop_write_file(filp); > > + > > + return ret; > > +} > > + > > static long __ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) > > { > > struct inode *inode = file_inode(filp); > > @@ -1509,6 +1586,10 @@ static long __ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) > > return ext4_ioctl_setlabel(filp, > > (const void __user *)arg); > > > > + case EXT4_IOC_GETFSUUID: > > + return ext4_ioctl_getuuid(EXT4_SB(sb), (void __user *)arg); > > + case EXT4_IOC_SETFSUUID: > > + return ext4_ioctl_setuuid(filp, (const void __user *)arg); > > default: > > return -ENOTTY; > > } > > @@ -1586,6 +1667,8 @@ long ext4_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) > > case EXT4_IOC_CHECKPOINT: > > case FS_IOC_GETFSLABEL: > > case FS_IOC_SETFSLABEL: > > + case EXT4_IOC_GETFSUUID: > > + case EXT4_IOC_SETFSUUID: > > break; > > default: > > return -ENOIOCTLCMD; > > -- > > 2.37.0.rc0.161.g10f37bed90-goog > >
On Mon, Jul 11, 2022 at 09:33:00PM -0700, Jeremy Bongio wrote: > On Tue, Jul 5, 2022 at 10:07 AM Darrick J. Wong <djwong@kernel.org> wrote: > > > > On Fri, Jul 01, 2022 at 01:11:23PM -0700, Jeremy Bongio wrote: > > > This fixes a race between changing the ext4 superblock uuid and operations > > > like mounting, resizing, changing features, etc. > > > > > > Reviewed-by: Theodore Ts'o <tytso@mit.edu> > > > Signed-off-by: Jeremy Bongio <bongiojp@gmail.com> > > > --- > > > fs/ext4/ext4.h | 13 ++++++++ > > > fs/ext4/ioctl.c | 83 +++++++++++++++++++++++++++++++++++++++++++++++++ > > > 2 files changed, 96 insertions(+) > > > > > > diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h > > > index 75b8d81b2469..0cf960cb591e 100644 > > > --- a/fs/ext4/ext4.h > > > +++ b/fs/ext4/ext4.h > > > @@ -724,6 +724,8 @@ enum { > > > #define EXT4_IOC_GETSTATE _IOW('f', 41, __u32) > > > #define EXT4_IOC_GET_ES_CACHE _IOWR('f', 42, struct fiemap) > > > #define EXT4_IOC_CHECKPOINT _IOW('f', 43, __u32) > > > +#define EXT4_IOC_GETFSUUID _IOR('f', 44, struct fsuuid) > > > +#define EXT4_IOC_SETFSUUID _IOW('f', 44, struct fsuuid) > > > > > > #define EXT4_IOC_SHUTDOWN _IOR ('X', 125, __u32) > > > > > > @@ -753,6 +755,17 @@ enum { > > > EXT4_IOC_CHECKPOINT_FLAG_ZEROOUT | \ > > > EXT4_IOC_CHECKPOINT_FLAG_DRY_RUN) > > > > > > +/* > > > + * Structure for EXT4_IOC_GETFSUUID/EXT4_IOC_SETFSUUID > > > + */ > > > +struct fsuuid { > > > + __u32 fu_len; > > > + __u32 fu_flags; > > > + __u8 __user fu_uuid[]; > > > > __user is unnecessary here -- it applies to pointers, not to struct > > members. > > > > > +}; > > > + > > > +#define EXT4_IOC_SETFSUUID_FLAG_BLOCKING 0x1 > > > > What does this do? > > > > (Better yet, can you please write a manpage describing these new > > ioctls?) > > Good idea. I'll write a manpage as if it were being converted to a general ioctl > and not specific to ext4. Thank you. :) > > > > > + > > > #if defined(__KERNEL__) && defined(CONFIG_COMPAT) > > > /* > > > * ioctl commands in 32 bit emulation > > > diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c > > > index cb01c1da0f9d..75069afc16ae 100644 > > > --- a/fs/ext4/ioctl.c > > > +++ b/fs/ext4/ioctl.c > > > @@ -20,6 +20,7 @@ > > > #include <linux/delay.h> > > > #include <linux/iversion.h> > > > #include <linux/fileattr.h> > > > +#include <linux/uuid.h> > > > #include "ext4_jbd2.h" > > > #include "ext4.h" > > > #include <linux/fsmap.h> > > > @@ -41,6 +42,15 @@ static void ext4_sb_setlabel(struct ext4_super_block *es, const void *arg) > > > memcpy(es->s_volume_name, (char *)arg, EXT4_LABEL_MAX); > > > } > > > > > > +/* > > > + * Superblock modification callback function for changing file system > > > + * UUID. > > > + */ > > > +static void ext4_sb_setuuid(struct ext4_super_block *es, const void *arg) > > > +{ > > > + memcpy(es->s_uuid, (__u8 *)arg, UUID_SIZE); > > > +} > > > + > > > static > > > int ext4_update_primary_sb(struct super_block *sb, handle_t *handle, > > > ext4_update_sb_callback func, > > > @@ -1131,6 +1141,73 @@ static int ext4_ioctl_getlabel(struct ext4_sb_info *sbi, char __user *user_label > > > return 0; > > > } > > > > > > +static int ext4_ioctl_getuuid(struct ext4_sb_info *sbi, > > > + struct fsuuid __user *ufsuuid) > > > +{ > > > + int ret = 0; > > > + __u8 uuid[UUID_SIZE]; > > > > Save some stack space and copy sbi->s_es->s_uuid into fsuuid.fu_uuid, > > and then copy_to_user from the kernel stack object out to userspace's > > object. > > I can't copy sbi->s_es->s_uuid into fsuuid.fu_uuid since fu_uuid is a > VLA (size 0 array). > Are you suggesting I copy_to_user() from sbi->s_es->s_uuid into > ufsuuid within the locked region? No, I'd ... forgotten my own previous suggestion, so please ignore this. > > > > > + struct fsuuid fsuuid; > > > + > > > + if (copy_from_user(&fsuuid, ufsuuid, sizeof(fsuuid))) > > > + return -EFAULT; > > > + > > > + if (fsuuid.fu_len != UUID_SIZE) > > > + return -EINVAL; > > > > This function needs to check that fsuuid.fu_flags doesn't contain any > > unknown bitflags. > > > > > + > > > + lock_buffer(sbi->s_sbh); > > > + memcpy(uuid, sbi->s_es->s_uuid, UUID_SIZE); > > > + unlock_buffer(sbi->s_sbh); > > > + > > > + if (copy_to_user(&ufsuuid->fu_uuid[0], uuid, UUID_SIZE)) > > > + ret = -EFAULT; > > > + return ret; > > > > if (copy_to_user(...)) > > return -EFAULT; > > > > return 0; > > > > ? > > > > > +} > > > + > > > +static int ext4_ioctl_setuuid(struct file *filp, > > > + const struct fsuuid __user *ufsuuid) > > > +{ > > > + int ret = 0; > > > + struct super_block *sb = file_inode(filp)->i_sb; > > > + struct fsuuid fsuuid; > > > + __u8 uuid[UUID_SIZE]; > > > + > > > + if (!capable(CAP_SYS_ADMIN)) > > > + return -EPERM; > > > + > > > + /* > > > + * If any checksums (group descriptors or metadata) are being used > > > + * then the checksum seed feature is required to change the UUID. > > > + */ > > > + if (((ext4_has_feature_gdt_csum(sb) || ext4_has_metadata_csum(sb)) > > > + && !ext4_has_feature_csum_seed(sb)) > > > + || ext4_has_feature_stable_inodes(sb)) > > > + return -EOPNOTSUPP; > > > + > > > + if (copy_from_user(&fsuuid, ufsuuid, sizeof(fsuuid))) > > > + return -EFAULT; > > > + > > > + if (fsuuid.fu_len != UUID_SIZE) > > > + return -EINVAL; > > > > This function needs to check that fsuuid.fu_flags doesn't contain any > > unknown bits. > > > > > + > > > + if (copy_from_user(uuid, &ufsuuid->fu_uuid[0], UUID_SIZE)) > > > + return -EFAULT; > > > + > > > + ret = mnt_want_write_file(filp); > > > + if (ret) > > > + return ret; > > > + > > > + do { > > > + if (ret == -EBUSY) > > > + msleep(1000); > > > + ret = ext4_update_superblocks_fn(sb, ext4_sb_setuuid, &uuid); > > > + } while (ret == -EBUSY && > > > + fsuuid.fu_flags & EXT4_IOC_SETFSUUID_FLAG_BLOCKING); > > > > So... I guess by default, userspace gets NOWAIT mode? That's a little > > strange, usually kernel convention is blocking mode by default, with > > nowait selectable via function flags. > > > > Also, what's the intended use case here? Why would we want to set a > > uuid but only if the superblock(s) aren't busy? > > When an ext4 filesystem is being resized, which could potentially take > a long time, > ext4_update_superblocks_fn() will return -EBUSY. In that case we can > either sleep and retry, > or return EBUSY to userspace. However, for my use case, I only care > about the blocking case. > I'll remove the flag since the default mode will be blocking. <nod> --D > > > > > --D > > > > > + > > > + mnt_drop_write_file(filp); > > > + > > > + return ret; > > > +} > > > + > > > static long __ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) > > > { > > > struct inode *inode = file_inode(filp); > > > @@ -1509,6 +1586,10 @@ static long __ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) > > > return ext4_ioctl_setlabel(filp, > > > (const void __user *)arg); > > > > > > + case EXT4_IOC_GETFSUUID: > > > + return ext4_ioctl_getuuid(EXT4_SB(sb), (void __user *)arg); > > > + case EXT4_IOC_SETFSUUID: > > > + return ext4_ioctl_setuuid(filp, (const void __user *)arg); > > > default: > > > return -ENOTTY; > > > } > > > @@ -1586,6 +1667,8 @@ long ext4_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) > > > case EXT4_IOC_CHECKPOINT: > > > case FS_IOC_GETFSLABEL: > > > case FS_IOC_SETFSLABEL: > > > + case EXT4_IOC_GETFSUUID: > > > + case EXT4_IOC_SETFSUUID: > > > break; > > > default: > > > return -ENOIOCTLCMD; > > > -- > > > 2.37.0.rc0.161.g10f37bed90-goog > > >
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 75b8d81b2469..0cf960cb591e 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -724,6 +724,8 @@ enum { #define EXT4_IOC_GETSTATE _IOW('f', 41, __u32) #define EXT4_IOC_GET_ES_CACHE _IOWR('f', 42, struct fiemap) #define EXT4_IOC_CHECKPOINT _IOW('f', 43, __u32) +#define EXT4_IOC_GETFSUUID _IOR('f', 44, struct fsuuid) +#define EXT4_IOC_SETFSUUID _IOW('f', 44, struct fsuuid) #define EXT4_IOC_SHUTDOWN _IOR ('X', 125, __u32) @@ -753,6 +755,17 @@ enum { EXT4_IOC_CHECKPOINT_FLAG_ZEROOUT | \ EXT4_IOC_CHECKPOINT_FLAG_DRY_RUN) +/* + * Structure for EXT4_IOC_GETFSUUID/EXT4_IOC_SETFSUUID + */ +struct fsuuid { + __u32 fu_len; + __u32 fu_flags; + __u8 __user fu_uuid[]; +}; + +#define EXT4_IOC_SETFSUUID_FLAG_BLOCKING 0x1 + #if defined(__KERNEL__) && defined(CONFIG_COMPAT) /* * ioctl commands in 32 bit emulation diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c index cb01c1da0f9d..75069afc16ae 100644 --- a/fs/ext4/ioctl.c +++ b/fs/ext4/ioctl.c @@ -20,6 +20,7 @@ #include <linux/delay.h> #include <linux/iversion.h> #include <linux/fileattr.h> +#include <linux/uuid.h> #include "ext4_jbd2.h" #include "ext4.h" #include <linux/fsmap.h> @@ -41,6 +42,15 @@ static void ext4_sb_setlabel(struct ext4_super_block *es, const void *arg) memcpy(es->s_volume_name, (char *)arg, EXT4_LABEL_MAX); } +/* + * Superblock modification callback function for changing file system + * UUID. + */ +static void ext4_sb_setuuid(struct ext4_super_block *es, const void *arg) +{ + memcpy(es->s_uuid, (__u8 *)arg, UUID_SIZE); +} + static int ext4_update_primary_sb(struct super_block *sb, handle_t *handle, ext4_update_sb_callback func, @@ -1131,6 +1141,73 @@ static int ext4_ioctl_getlabel(struct ext4_sb_info *sbi, char __user *user_label return 0; } +static int ext4_ioctl_getuuid(struct ext4_sb_info *sbi, + struct fsuuid __user *ufsuuid) +{ + int ret = 0; + __u8 uuid[UUID_SIZE]; + struct fsuuid fsuuid; + + if (copy_from_user(&fsuuid, ufsuuid, sizeof(fsuuid))) + return -EFAULT; + + if (fsuuid.fu_len != UUID_SIZE) + return -EINVAL; + + lock_buffer(sbi->s_sbh); + memcpy(uuid, sbi->s_es->s_uuid, UUID_SIZE); + unlock_buffer(sbi->s_sbh); + + if (copy_to_user(&ufsuuid->fu_uuid[0], uuid, UUID_SIZE)) + ret = -EFAULT; + return ret; +} + +static int ext4_ioctl_setuuid(struct file *filp, + const struct fsuuid __user *ufsuuid) +{ + int ret = 0; + struct super_block *sb = file_inode(filp)->i_sb; + struct fsuuid fsuuid; + __u8 uuid[UUID_SIZE]; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + /* + * If any checksums (group descriptors or metadata) are being used + * then the checksum seed feature is required to change the UUID. + */ + if (((ext4_has_feature_gdt_csum(sb) || ext4_has_metadata_csum(sb)) + && !ext4_has_feature_csum_seed(sb)) + || ext4_has_feature_stable_inodes(sb)) + return -EOPNOTSUPP; + + if (copy_from_user(&fsuuid, ufsuuid, sizeof(fsuuid))) + return -EFAULT; + + if (fsuuid.fu_len != UUID_SIZE) + return -EINVAL; + + if (copy_from_user(uuid, &ufsuuid->fu_uuid[0], UUID_SIZE)) + return -EFAULT; + + ret = mnt_want_write_file(filp); + if (ret) + return ret; + + do { + if (ret == -EBUSY) + msleep(1000); + ret = ext4_update_superblocks_fn(sb, ext4_sb_setuuid, &uuid); + } while (ret == -EBUSY && + fsuuid.fu_flags & EXT4_IOC_SETFSUUID_FLAG_BLOCKING); + + mnt_drop_write_file(filp); + + return ret; +} + static long __ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) { struct inode *inode = file_inode(filp); @@ -1509,6 +1586,10 @@ static long __ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) return ext4_ioctl_setlabel(filp, (const void __user *)arg); + case EXT4_IOC_GETFSUUID: + return ext4_ioctl_getuuid(EXT4_SB(sb), (void __user *)arg); + case EXT4_IOC_SETFSUUID: + return ext4_ioctl_setuuid(filp, (const void __user *)arg); default: return -ENOTTY; } @@ -1586,6 +1667,8 @@ long ext4_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) case EXT4_IOC_CHECKPOINT: case FS_IOC_GETFSLABEL: case FS_IOC_SETFSLABEL: + case EXT4_IOC_GETFSUUID: + case EXT4_IOC_SETFSUUID: break; default: return -ENOIOCTLCMD;