From: Dan Williams <dan.j.williams@intel.com> mainline inclusion from mainline-v6.16-rc1 commit fba4ceaa242d2bdf4c04b77bda41d32d02d3925d category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IBWQ24 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- Unlike sysfs, the lifetime of configfs objects is controlled by userspace. There is no mechanism for the kernel to find and delete all created config-items. Instead, the configfs-tsm-report mechanism has an expectation that tsm_unregister() can happen at any time and cause established config-item access to start failing. That expectation is not fully satisfied. While tsm_report_read(), tsm_report_{is,is_bin}_visible(), and tsm_report_make_item() safely fail if tsm_ops have been unregistered, tsm_report_privlevel_store() tsm_report_provider_show() fail to check for ops registration. Add the missing checks for tsm_ops having been removed. Now, in supporting the ability for tsm_unregister() to always succeed, it leaves the problem of what to do with lingering config-items. The expectation is that the admin that arranges for the ->remove() (unbind) of the ${tsm_arch}-guest driver is also responsible for deletion of all open config-items. Until that deletion happens, ->probe() (reload / bind) of the ${tsm_arch}-guest driver fails. This allows for emergency shutdown / revocation of attestation interfaces, and requires coordinated restart. Fixes: 70e6f7e2b985 ("configfs-tsm: Introduce a shared ABI for attestation reports") Cc: stable@vger.kernel.org Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Steven Price <steven.price@arm.com> Cc: Sami Mujawar <sami.mujawar@arm.com> Cc: Borislav Petkov (AMD) <bp@alien8.de> Cc: Tom Lendacky <thomas.lendacky@amd.com> Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> Reported-by: Cedric Xing <cedric.xing@intel.com> Reviewed-by: Kai Huang <kai.huang@intel.com> Link: https://patch.msgid.link/20250430203331.1177062-1-dan.j.williams@intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com> Conflicts: drivers/virt/coco/tsm.c [Because the commit 20dfee959364 ("x86/sev: Take advantage of configfs visibility support in TSM") is not merged, result in context conflicts.] Signed-off-by: Cai Xinchen <caixinchen1@huawei.com> --- drivers/virt/coco/tsm.c | 31 +++++++++++++++++++++++++++++-- 1 file changed, 29 insertions(+), 2 deletions(-) diff --git a/drivers/virt/coco/tsm.c b/drivers/virt/coco/tsm.c index d1c2db83a8ca..9c80966dd7b6 100644 --- a/drivers/virt/coco/tsm.c +++ b/drivers/virt/coco/tsm.c @@ -16,6 +16,7 @@ static struct tsm_provider { const struct tsm_ops *ops; const struct config_item_type *type; void *data; + atomic_t count; } provider; static DECLARE_RWSEM(tsm_rwsem); @@ -92,6 +93,10 @@ static ssize_t tsm_report_privlevel_store(struct config_item *cfg, if (rc) return rc; + guard(rwsem_write)(&tsm_rwsem); + if (!provider.ops) + return -ENXIO; + /* * The valid privilege levels that a TSM might accept, if it accepts a * privilege level setting at all, are a max of TSM_PRIVLEVEL_MAX (see @@ -101,7 +106,6 @@ static ssize_t tsm_report_privlevel_store(struct config_item *cfg, if (provider.ops->privlevel_floor > val || val > TSM_PRIVLEVEL_MAX) return -EINVAL; - guard(rwsem_write)(&tsm_rwsem); rc = try_advance_write_generation(report); if (rc) return rc; @@ -115,6 +119,10 @@ static ssize_t tsm_report_privlevel_floor_show(struct config_item *cfg, char *buf) { guard(rwsem_read)(&tsm_rwsem); + + if (!provider.ops) + return -ENXIO; + return sysfs_emit(buf, "%u\n", provider.ops->privlevel_floor); } CONFIGFS_ATTR_RO(tsm_report_, privlevel_floor); @@ -149,6 +157,9 @@ CONFIGFS_ATTR_RO(tsm_report_, generation); static ssize_t tsm_report_provider_show(struct config_item *cfg, char *buf) { guard(rwsem_read)(&tsm_rwsem); + if (!provider.ops) + return -ENXIO; + return sysfs_emit(buf, "%s\n", provider.ops->name); } CONFIGFS_ATTR_RO(tsm_report_, provider); @@ -213,7 +224,7 @@ static ssize_t tsm_report_read(struct tsm_report *report, void *buf, guard(rwsem_write)(&tsm_rwsem); ops = provider.ops; if (!ops) - return -ENOTTY; + return -ENXIO; if (!report->desc.inblob_len) return -EINVAL; @@ -326,12 +337,20 @@ static struct config_item *tsm_report_make_item(struct config_group *group, if (!state) return ERR_PTR(-ENOMEM); + atomic_inc(&provider.count); config_item_init_type_name(&state->cfg, name, provider.type); return &state->cfg; } +static void tsm_report_drop_item(struct config_group *group, struct config_item *item) +{ + config_item_put(item); + atomic_dec(&provider.count); +} + static struct configfs_group_operations tsm_report_group_ops = { .make_item = tsm_report_make_item, + .drop_item = tsm_report_drop_item, }; static const struct config_item_type tsm_reports_type = { @@ -370,6 +389,11 @@ int tsm_register(const struct tsm_ops *ops, void *priv, return -EBUSY; } + if (atomic_read(&provider.count)) { + pr_err("configfs/tsm/report not empty\n"); + return -EBUSY; + } + provider.ops = ops; provider.data = priv; provider.type = type; @@ -382,6 +406,9 @@ int tsm_unregister(const struct tsm_ops *ops) guard(rwsem_write)(&tsm_rwsem); if (ops != provider.ops) return -EBUSY; + if (atomic_read(&provider.count)) + pr_warn("\"%s\" unregistered with items present in configfs/tsm/report\n", + provider.ops->name); provider.ops = NULL; provider.data = NULL; provider.type = NULL; -- 2.18.0.huawei.25