| Message ID | 20230612215139.5132-3-Avadhut.Naik@amd.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | Add support for Vendor Defined Error Types in Einj Module | expand |
On Mon, Jun 12, 2023 at 09:51:38PM +0000, Avadhut Naik wrote: > /** > - * debugfs_create_blob - create a debugfs file that is used to read a binary blob > + * debugfs_create_blob - create a debugfs file that is used to read and write > + * a binary blob > * @name: a pointer to a string containing the name of the file to create. > - * @mode: the read permission that the file should have (other permissions are > - * masked out) > + * @mode: the permission that the file should have > * @parent: a pointer to the parent dentry for this file. This should be a > * directory dentry if set. If this parameter is %NULL, then the > * file will be created in the root of the debugfs filesystem. > @@ -992,7 +1010,7 @@ static const struct file_operations fops_blob = { > * > * This function creates a file in debugfs with the given name that exports > * @blob->data as a binary blob. If the @mode variable is so set it can be > - * read from. Writing is not supported. > + * read from and written to. > * > * This function will return a pointer to a dentry if it succeeds. This > * pointer must be passed to the debugfs_remove() function when the file is > @@ -1007,7 +1025,7 @@ struct dentry *debugfs_create_blob(const char *name, umode_t mode, > struct dentry *parent, > struct debugfs_blob_wrapper *blob) > { > - return debugfs_create_file_unsafe(name, mode & 0444, parent, blob, &fops_blob); > + return debugfs_create_file_unsafe(name, mode, parent, blob, &fops_blob); Have you audited all calls to this function to verify that you haven't just turned on write access to some debugfs files? Why not rename this to debugfs_create_blob_wo() and then make a new debugfs_create_blob_rw() call to ensure that it all is ok? thanks, greg k-h
On 13/6/23 17:59, Greg KH wrote: > On Mon, Jun 12, 2023 at 09:51:38PM +0000, Avadhut Naik wrote: >> /** >> - * debugfs_create_blob - create a debugfs file that is used to read a binary blob >> + * debugfs_create_blob - create a debugfs file that is used to read and write >> + * a binary blob >> * @name: a pointer to a string containing the name of the file to create. >> - * @mode: the read permission that the file should have (other permissions are >> - * masked out) >> + * @mode: the permission that the file should have >> * @parent: a pointer to the parent dentry for this file. This should be a >> * directory dentry if set. If this parameter is %NULL, then the >> * file will be created in the root of the debugfs filesystem. >> @@ -992,7 +1010,7 @@ static const struct file_operations fops_blob = { >> * >> * This function creates a file in debugfs with the given name that exports >> * @blob->data as a binary blob. If the @mode variable is so set it can be >> - * read from. Writing is not supported. >> + * read from and written to. >> * >> * This function will return a pointer to a dentry if it succeeds. This >> * pointer must be passed to the debugfs_remove() function when the file is >> @@ -1007,7 +1025,7 @@ struct dentry *debugfs_create_blob(const char *name, umode_t mode, >> struct dentry *parent, >> struct debugfs_blob_wrapper *blob) >> { >> - return debugfs_create_file_unsafe(name, mode & 0444, parent, blob, &fops_blob); >> + return debugfs_create_file_unsafe(name, mode, parent, blob, &fops_blob); > > Have you audited all calls to this function to verify that you haven't > just turned on write access to some debugfs files? I just did, it is one of S_IRUGO/S_IRUSR/0444/0400/(S_IFREG | 0444). So we are quite safe here. Except (S_IFREG | 0444) in drivers/platform/chrome/cros_ec_debugfs.c which seems wrong as debugfs files are not regular files. > Why not rename this to debugfs_create_blob_wo() and then make a new > debugfs_create_blob_rw() call to ensure that it all is ok? It is already taking the mode for this purpose. imho just cros_ec_create_panicinfo()'s debugfs_create_blob("panicinfo", S_IFREG | 0444,...) needs fixing. > > thanks, > > greg k-h
On Tue, Jun 13, 2023 at 08:05:41PM +1000, Alexey Kardashevskiy wrote: > > > On 13/6/23 17:59, Greg KH wrote: > > On Mon, Jun 12, 2023 at 09:51:38PM +0000, Avadhut Naik wrote: > > > /** > > > - * debugfs_create_blob - create a debugfs file that is used to read a binary blob > > > + * debugfs_create_blob - create a debugfs file that is used to read and write > > > + * a binary blob > > > * @name: a pointer to a string containing the name of the file to create. > > > - * @mode: the read permission that the file should have (other permissions are > > > - * masked out) > > > + * @mode: the permission that the file should have > > > * @parent: a pointer to the parent dentry for this file. This should be a > > > * directory dentry if set. If this parameter is %NULL, then the > > > * file will be created in the root of the debugfs filesystem. > > > @@ -992,7 +1010,7 @@ static const struct file_operations fops_blob = { > > > * > > > * This function creates a file in debugfs with the given name that exports > > > * @blob->data as a binary blob. If the @mode variable is so set it can be > > > - * read from. Writing is not supported. > > > + * read from and written to. > > > * > > > * This function will return a pointer to a dentry if it succeeds. This > > > * pointer must be passed to the debugfs_remove() function when the file is > > > @@ -1007,7 +1025,7 @@ struct dentry *debugfs_create_blob(const char *name, umode_t mode, > > > struct dentry *parent, > > > struct debugfs_blob_wrapper *blob) > > > { > > > - return debugfs_create_file_unsafe(name, mode & 0444, parent, blob, &fops_blob); > > > + return debugfs_create_file_unsafe(name, mode, parent, blob, &fops_blob); > > > > Have you audited all calls to this function to verify that you haven't > > just turned on write access to some debugfs files? > > I just did, it is one of S_IRUGO/S_IRUSR/0444/0400/(S_IFREG | 0444). So we > are quite safe here. Except (S_IFREG | 0444) in > drivers/platform/chrome/cros_ec_debugfs.c which seems wrong as debugfs files > are not regular files. > > > Why not rename this to debugfs_create_blob_wo() and then make a new > > debugfs_create_blob_rw() call to ensure that it all is ok? > > It is already taking the mode for this purpose. imho just > cros_ec_create_panicinfo()'s debugfs_create_blob("panicinfo", S_IFREG | > 0444,...) needs fixing. Yes, well it's taking the mode, but silently modifying it :) Ok, thanks for the audit, respin this with that fix and then I don't have a problem with it (other than binary debugfs files fill me with dread, what could go wrong...) thanks, greg k-h
Hi, Thanks for reviewing! On 6/13/2023 05:22, Greg KH wrote: > On Tue, Jun 13, 2023 at 08:05:41PM +1000, Alexey Kardashevskiy wrote: >> >> >> On 13/6/23 17:59, Greg KH wrote: >>> On Mon, Jun 12, 2023 at 09:51:38PM +0000, Avadhut Naik wrote: >>>> /** >>>> - * debugfs_create_blob - create a debugfs file that is used to read a binary blob >>>> + * debugfs_create_blob - create a debugfs file that is used to read and write >>>> + * a binary blob >>>> * @name: a pointer to a string containing the name of the file to create. >>>> - * @mode: the read permission that the file should have (other permissions are >>>> - * masked out) >>>> + * @mode: the permission that the file should have >>>> * @parent: a pointer to the parent dentry for this file. This should be a >>>> * directory dentry if set. If this parameter is %NULL, then the >>>> * file will be created in the root of the debugfs filesystem. >>>> @@ -992,7 +1010,7 @@ static const struct file_operations fops_blob = { >>>> * >>>> * This function creates a file in debugfs with the given name that exports >>>> * @blob->data as a binary blob. If the @mode variable is so set it can be >>>> - * read from. Writing is not supported. >>>> + * read from and written to. >>>> * >>>> * This function will return a pointer to a dentry if it succeeds. This >>>> * pointer must be passed to the debugfs_remove() function when the file is >>>> @@ -1007,7 +1025,7 @@ struct dentry *debugfs_create_blob(const char *name, umode_t mode, >>>> struct dentry *parent, >>>> struct debugfs_blob_wrapper *blob) >>>> { >>>> - return debugfs_create_file_unsafe(name, mode & 0444, parent, blob, &fops_blob); >>>> + return debugfs_create_file_unsafe(name, mode, parent, blob, &fops_blob); >>> >>> Have you audited all calls to this function to verify that you haven't >>> just turned on write access to some debugfs files? >> >> I just did, it is one of S_IRUGO/S_IRUSR/0444/0400/(S_IFREG | 0444). So we >> are quite safe here. Except (S_IFREG | 0444) in >> drivers/platform/chrome/cros_ec_debugfs.c which seems wrong as debugfs files >> are not regular files. >> >>> Why not rename this to debugfs_create_blob_wo() and then make a new >>> debugfs_create_blob_rw() call to ensure that it all is ok? >> >> It is already taking the mode for this purpose. imho just >> cros_ec_create_panicinfo()'s debugfs_create_blob("panicinfo", S_IFREG | >> 0444,...) needs fixing. > > Yes, well it's taking the mode, but silently modifying it :) > > Ok, thanks for the audit, respin this with that fix and then I don't > have a problem with it (other than binary debugfs files fill me with > dread, what could go wrong...) > Will add the fix for cros_ec_create_panicinfo()'s debugfs_create_blob() usage. Thanks, Avadhut Naik > thanks, > > greg k-h --
diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index 1f971c880dde..fab5a562b57c 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -973,17 +973,35 @@ static ssize_t read_file_blob(struct file *file, char __user *user_buf, return r; } +static ssize_t write_file_blob(struct file *file, const char __user *user_buf, + size_t count, loff_t *ppos) +{ + struct debugfs_blob_wrapper *blob = file->private_data; + struct dentry *dentry = F_DENTRY(file); + ssize_t r; + + r = debugfs_file_get(dentry); + if (unlikely(r)) + return r; + r = simple_write_to_buffer(blob->data, blob->size, ppos, user_buf, + count); + + debugfs_file_put(dentry); + return r; +} + static const struct file_operations fops_blob = { .read = read_file_blob, + .write = write_file_blob, .open = simple_open, .llseek = default_llseek, }; /** - * debugfs_create_blob - create a debugfs file that is used to read a binary blob + * debugfs_create_blob - create a debugfs file that is used to read and write + * a binary blob * @name: a pointer to a string containing the name of the file to create. - * @mode: the read permission that the file should have (other permissions are - * masked out) + * @mode: the permission that the file should have * @parent: a pointer to the parent dentry for this file. This should be a * directory dentry if set. If this parameter is %NULL, then the * file will be created in the root of the debugfs filesystem. @@ -992,7 +1010,7 @@ static const struct file_operations fops_blob = { * * This function creates a file in debugfs with the given name that exports * @blob->data as a binary blob. If the @mode variable is so set it can be - * read from. Writing is not supported. + * read from and written to. * * This function will return a pointer to a dentry if it succeeds. This * pointer must be passed to the debugfs_remove() function when the file is @@ -1007,7 +1025,7 @@ struct dentry *debugfs_create_blob(const char *name, umode_t mode, struct dentry *parent, struct debugfs_blob_wrapper *blob) { - return debugfs_create_file_unsafe(name, mode & 0444, parent, blob, &fops_blob); + return debugfs_create_file_unsafe(name, mode, parent, blob, &fops_blob); } EXPORT_SYMBOL_GPL(debugfs_create_blob);