Hi Ard, On Tue, 12 Dec 2023 at 07:39, Masahisa Kojima <masahisa.kojima@xxxxxxxxxx> wrote: > > Hi Ard, > > On Mon, 11 Dec 2023 at 19:02, Ard Biesheuvel <ardb@xxxxxxxxxx> wrote: > > > > On Fri, 13 Oct 2023 at 09:47, Masahisa Kojima > > <masahisa.kojima@xxxxxxxxxx> wrote: > > > > > > efivar operation is updated when the tee_stmm_efi module is probed. > > > tee_stmm_efi module supports SetVariable runtime service, > > > but user needs to manually remount the efivarfs as RW to enable > > > the write access if the previous efivar operation does not support > > > SerVariable and efivarfs is mounted as read-only. > > > > > > This commit notifies the update of efivar operation to > > > efivarfs subsystem, then drops SB_RDONLY flag if the efivar > > > operation supports SetVariable. > > > > > > Signed-off-by: Masahisa Kojima <masahisa.kojima@xxxxxxxxxx> > > > > Unfortunately, I have identified a problem with this approach. > > > > There are cases where there are multiple instances of struct > > superblock are associated with the efivarfs file system [0]. > > > > So I reworked the patch a little - please take the time to double > > check that I did not make any mistakes here. > > > > [0] https://lore.kernel.org/linux-efi/20231208163925.3225018-8-ardb@xxxxxxxxxx/T/#u > > I think you are referring to this patch[1]? > The modification should be OK, also I have tested it works as expected. > > Thank you very much for fixing this. Same results here (as we discussed yesterday on IRC). Code looks sane and the automatic remounting correctly sets the mountpoint as RW Thanks! /Ilias > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/fs/efivarfs?id=94f7f6182c72ba642c1f20111681f9cc8621c95f > > Thanks, > Masahisa Kojima > > > > > > > > --- > > > drivers/firmware/efi/efi.c | 6 ++++++ > > > drivers/firmware/efi/vars.c | 8 ++++++++ > > > fs/efivarfs/super.c | 33 +++++++++++++++++++++++++++++++++ > > > include/linux/efi.h | 8 ++++++++ > > > 4 files changed, 55 insertions(+) > > > > > > diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c > > > index 53ae25bbb6ac..d2eec5ed8e5e 100644 > > > --- a/drivers/firmware/efi/efi.c > > > +++ b/drivers/firmware/efi/efi.c > > > @@ -32,6 +32,7 @@ > > > #include <linux/ucs2_string.h> > > > #include <linux/memblock.h> > > > #include <linux/security.h> > > > +#include <linux/notifier.h> > > > > > > #include <asm/early_ioremap.h> > > > > > > @@ -187,6 +188,9 @@ static const struct attribute_group efi_subsys_attr_group = { > > > .is_visible = efi_attr_is_visible, > > > }; > > > > > > +struct blocking_notifier_head efivar_ops_nh; > > > +EXPORT_SYMBOL_GPL(efivar_ops_nh); > > > + > > > static struct efivars generic_efivars; > > > static struct efivar_operations generic_ops; > > > > > > @@ -427,6 +431,8 @@ static int __init efisubsys_init(void) > > > platform_device_register_simple("efivars", 0, NULL, 0); > > > } > > > > > > + BLOCKING_INIT_NOTIFIER_HEAD(&efivar_ops_nh); > > > + > > > error = sysfs_create_group(efi_kobj, &efi_subsys_attr_group); > > > if (error) { > > > pr_err("efi: Sysfs attribute export failed with error %d.\n", > > > diff --git a/drivers/firmware/efi/vars.c b/drivers/firmware/efi/vars.c > > > index e9dc7116daf1..f654e6f6af87 100644 > > > --- a/drivers/firmware/efi/vars.c > > > +++ b/drivers/firmware/efi/vars.c > > > @@ -63,6 +63,7 @@ int efivars_register(struct efivars *efivars, > > > const struct efivar_operations *ops) > > > { > > > int rv; > > > + int event; > > > > > > if (down_interruptible(&efivars_lock)) > > > return -EINTR; > > > @@ -77,6 +78,13 @@ int efivars_register(struct efivars *efivars, > > > > > > __efivars = efivars; > > > > > > + if (efivar_supports_writes()) > > > + event = EFIVAR_OPS_RDWR; > > > + else > > > + event = EFIVAR_OPS_RDONLY; > > > + > > > + blocking_notifier_call_chain(&efivar_ops_nh, event, NULL); > > > + > > > pr_info("Registered efivars operations\n"); > > > rv = 0; > > > out: > > > diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c > > > index e028fafa04f3..0f6e4d223aea 100644 > > > --- a/fs/efivarfs/super.c > > > +++ b/fs/efivarfs/super.c > > > @@ -14,11 +14,36 @@ > > > #include <linux/slab.h> > > > #include <linux/magic.h> > > > #include <linux/statfs.h> > > > +#include <linux/notifier.h> > > > > > > #include "internal.h" > > > > > > LIST_HEAD(efivarfs_list); > > > > > > +struct efivarfs_info { > > > + struct super_block *sb; > > > + struct notifier_block nb; > > > +}; > > > + > > > +static struct efivarfs_info info; > > > + > > > +static int efivarfs_ops_notifier(struct notifier_block *nb, unsigned long event, > > > + void *data) > > > +{ > > > + switch (event) { > > > + case EFIVAR_OPS_RDONLY: > > > + info.sb->s_flags |= SB_RDONLY; > > > + break; > > > + case EFIVAR_OPS_RDWR: > > > + info.sb->s_flags &= ~SB_RDONLY; > > > + break; > > > + default: > > > + return NOTIFY_DONE; > > > + } > > > + > > > + return NOTIFY_OK; > > > +} > > > + > > > static void efivarfs_evict_inode(struct inode *inode) > > > { > > > clear_inode(inode); > > > @@ -255,6 +280,12 @@ static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc) > > > if (!root) > > > return -ENOMEM; > > > > > > + info.sb = sb; > > > + info.nb.notifier_call = efivarfs_ops_notifier; > > > + err = blocking_notifier_chain_register(&efivar_ops_nh, &info.nb); > > > + if (err) > > > + return err; > > > + > > > INIT_LIST_HEAD(&efivarfs_list); > > > > > > err = efivar_init(efivarfs_callback, (void *)sb, true, &efivarfs_list); > > > @@ -281,6 +312,8 @@ static int efivarfs_init_fs_context(struct fs_context *fc) > > > > > > static void efivarfs_kill_sb(struct super_block *sb) > > > { > > > + blocking_notifier_chain_unregister(&efivar_ops_nh, &info.nb); > > > + info.sb = NULL; > > > kill_litter_super(sb); > > > > > > if (!efivar_is_available()) > > > diff --git a/include/linux/efi.h b/include/linux/efi.h > > > index 4776a3dd9a72..489707b9b0b0 100644 > > > --- a/include/linux/efi.h > > > +++ b/include/linux/efi.h > > > @@ -1355,6 +1355,14 @@ bool efi_config_table_is_usable(const efi_guid_t *guid, unsigned long table) > > > > > > umode_t efi_attr_is_visible(struct kobject *kobj, struct attribute *attr, int n); > > > > > > +/* > > > + * efivar ops event type > > > + */ > > > +#define EFIVAR_OPS_RDONLY 0 > > > +#define EFIVAR_OPS_RDWR 1 > > > + > > > +extern struct blocking_notifier_head efivar_ops_nh; > > > + > > > void efivars_generic_ops_register(void); > > > void efivars_generic_ops_unregister(void); > > > > > > -- > > > 2.30.2 > > >
