Hi Ilias, On Thu, 12 Oct 2023 at 02:00, Ilias Apalodimas <ilias.apalodimas@xxxxxxxxxx> wrote: > > Kojima-san > Apologies for the late reply, I just found some to test this. > > On Sun, 6 Aug 2023 at 19:55, 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. > > The RO->RW transition works fine and I did manage to test basic stuff > like setting up efibootmgr options. IIUC the RW->RO should be covered > by this patchset [0] ? Yes. > Wouldn't it be better to detect that the tee device of the supplicant > closes and use that to switch the permissions? I get why we need that > for the TPM, the entire subsystem needs to send TPM commands *before* > the supplicant dies. But this is not needed for the EFI variables > case, we could just remount the FS as RO the moment the supplicant > dies. OK, I will add the patch to restore the efivars generic ops when tee-supplicant stops. Thanks, Masahisa Kojima > > [0] https://lore.kernel.org/all/20230728134832.326467-1-sumit.garg@xxxxxxxxxx/ > > Regards > /Ilias > > > > Signed-off-by: Masahisa Kojima <masahisa.kojima@xxxxxxxxxx> > > --- > > 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 603bba2d6437..17cd628b5c42 100644 > > --- a/include/linux/efi.h > > +++ b/include/linux/efi.h > > @@ -1365,6 +1365,14 @@ 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 > >
