| Message ID | 20210915230127.2495723-1-kw@linux.com (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
| Series | [v3,1/3] PCI/sysfs: Check CAP_SYS_ADMIN before parsing user input | expand |
On Wed, Sep 15, 2021 at 11:01:25PM +0000, Krzysztof Wilczyński wrote: > Check if the "CAP_SYS_ADMIN" capability flag is set before parsing user > input as it makes more sense to first check whether the current user > actually has the right permissions before accepting any input from such > user. > > This will also make order in which enable_store() and msi_bus_store() > perform the "CAP_SYS_ADMIN" capability check consistent with other > PCI-related sysfs objects that first verify whether user has this > capability set. > > Signed-off-by: Krzysztof Wilczyński <kw@linux.com> Applied all three to pci/sysfs for v5.16, thanks! > --- > drivers/pci/pci-sysfs.c | 15 ++++++++------- > 1 file changed, 8 insertions(+), 7 deletions(-) > > diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c > index 7fb5cd17cc98..6832e161be1c 100644 > --- a/drivers/pci/pci-sysfs.c > +++ b/drivers/pci/pci-sysfs.c > @@ -273,15 +273,16 @@ static ssize_t enable_store(struct device *dev, struct device_attribute *attr, > { > struct pci_dev *pdev = to_pci_dev(dev); > unsigned long val; > - ssize_t result = kstrtoul(buf, 0, &val); > - > - if (result < 0) > - return result; > + ssize_t result; > > /* this can crash the machine when done on the "wrong" device */ > if (!capable(CAP_SYS_ADMIN)) > return -EPERM; > > + result = kstrtoul(buf, 0, &val); > + if (result < 0) > + return result; > + > device_lock(dev); > if (dev->driver) > result = -EBUSY; > @@ -378,12 +379,12 @@ static ssize_t msi_bus_store(struct device *dev, struct device_attribute *attr, > struct pci_bus *subordinate = pdev->subordinate; > unsigned long val; > > - if (kstrtoul(buf, 0, &val) < 0) > - return -EINVAL; > - > if (!capable(CAP_SYS_ADMIN)) > return -EPERM; > > + if (kstrtoul(buf, 0, &val) < 0) > + return -EINVAL; > + > /* > * "no_msi" and "bus_flags" only affect what happens when a driver > * requests MSI or MSI-X. They don't affect any drivers that have > -- > 2.33.0 >
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index 7fb5cd17cc98..6832e161be1c 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -273,15 +273,16 @@ static ssize_t enable_store(struct device *dev, struct device_attribute *attr, { struct pci_dev *pdev = to_pci_dev(dev); unsigned long val; - ssize_t result = kstrtoul(buf, 0, &val); - - if (result < 0) - return result; + ssize_t result; /* this can crash the machine when done on the "wrong" device */ if (!capable(CAP_SYS_ADMIN)) return -EPERM; + result = kstrtoul(buf, 0, &val); + if (result < 0) + return result; + device_lock(dev); if (dev->driver) result = -EBUSY; @@ -378,12 +379,12 @@ static ssize_t msi_bus_store(struct device *dev, struct device_attribute *attr, struct pci_bus *subordinate = pdev->subordinate; unsigned long val; - if (kstrtoul(buf, 0, &val) < 0) - return -EINVAL; - if (!capable(CAP_SYS_ADMIN)) return -EPERM; + if (kstrtoul(buf, 0, &val) < 0) + return -EINVAL; + /* * "no_msi" and "bus_flags" only affect what happens when a driver * requests MSI or MSI-X. They don't affect any drivers that have
Check if the "CAP_SYS_ADMIN" capability flag is set before parsing user input as it makes more sense to first check whether the current user actually has the right permissions before accepting any input from such user. This will also make order in which enable_store() and msi_bus_store() perform the "CAP_SYS_ADMIN" capability check consistent with other PCI-related sysfs objects that first verify whether user has this capability set. Signed-off-by: Krzysztof Wilczyński <kw@linux.com> --- drivers/pci/pci-sysfs.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-)