From c80a67bd5d13e691f730115615885736acc5f1a7 Mon Sep 17 00:00:00 2001 From: Xu Wang Date: Thu, 9 Jul 2020 05:40:33 +0000 Subject: debugfs: file: Remove unnecessary cast in kfree() Remove unnecassary casts in the argument to kfree. Signed-off-by: Xu Wang Link: https://lore.kernel.org/r/20200709054033.30148-1-vulab@iscas.ac.cn Signed-off-by: Greg Kroah-Hartman --- fs/debugfs/file.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/debugfs') diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index ae49a55bda00..3753c4c484fc 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -273,7 +273,7 @@ static int full_proxy_release(struct inode *inode, struct file *filp) r = real_fops->release(inode, filp); replace_fops(filp, d_inode(dentry)->i_fop); - kfree((void *)proxy_fops); + kfree(proxy_fops); fops_put(real_fops); return r; } -- cgit From a2b992c828f7651db369ba8f0eb0818d70232636 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Thu, 9 Jul 2020 17:42:44 -0700 Subject: debugfs: make sure we can remove u32_array files cleanly debugfs_create_u32_array() allocates a small structure to wrap the data and size information about the array. If users ever try to remove the file this leads to a leak since nothing ever frees this wrapper. That said there are no upstream users of debugfs_create_u32_array() that'd remove a u32 array file (we only have one u32 array user in CMA), so there is no real bug here. Make callers pass a wrapper they allocated. This way the lifetime management of the wrapper is on the caller, and we can avoid the potential leak in debugfs. CC: Chucheng Luo Signed-off-by: Jakub Kicinski Reviewed-by: Greg Kroah-Hartman Signed-off-by: David S. Miller --- fs/debugfs/file.c | 27 +++++++-------------------- 1 file changed, 7 insertions(+), 20 deletions(-) (limited to 'fs/debugfs') diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index ae49a55bda00..d0ed71f37511 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -918,11 +918,6 @@ struct dentry *debugfs_create_blob(const char *name, umode_t mode, } EXPORT_SYMBOL_GPL(debugfs_create_blob); -struct array_data { - void *array; - u32 elements; -}; - static size_t u32_format_array(char *buf, size_t bufsize, u32 *array, int array_size) { @@ -943,8 +938,8 @@ static size_t u32_format_array(char *buf, size_t bufsize, static int u32_array_open(struct inode *inode, struct file *file) { - struct array_data *data = inode->i_private; - int size, elements = data->elements; + struct debugfs_u32_array *data = inode->i_private; + int size, elements = data->n_elements; char *buf; /* @@ -959,7 +954,7 @@ static int u32_array_open(struct inode *inode, struct file *file) buf[size] = 0; file->private_data = buf; - u32_format_array(buf, size, data->array, data->elements); + u32_format_array(buf, size, data->array, data->n_elements); return nonseekable_open(inode, file); } @@ -996,8 +991,7 @@ static const struct file_operations u32_array_fops = { * @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. - * @array: u32 array that provides data. - * @elements: total number of elements in the array. + * @array: wrapper struct containing data pointer and size of the array. * * This function creates a file in debugfs with the given name that exports * @array as data. If the @mode variable is so set it can be read from. @@ -1005,17 +999,10 @@ static const struct file_operations u32_array_fops = { * Once array is created its size can not be changed. */ void debugfs_create_u32_array(const char *name, umode_t mode, - struct dentry *parent, u32 *array, u32 elements) + struct dentry *parent, + struct debugfs_u32_array *array) { - struct array_data *data = kmalloc(sizeof(*data), GFP_KERNEL); - - if (data == NULL) - return; - - data->array = array; - data->elements = elements; - - debugfs_create_file_unsafe(name, mode, parent, data, &u32_array_fops); + debugfs_create_file_unsafe(name, mode, parent, array, &u32_array_fops); } EXPORT_SYMBOL_GPL(debugfs_create_u32_array); -- cgit From a24c6f7bc923d5e2f3139855eb09b0d480d6b410 Mon Sep 17 00:00:00 2001 From: Peter Enderborg Date: Thu, 16 Jul 2020 09:15:11 +0200 Subject: debugfs: Add access restriction option Since debugfs include sensitive information it need to be treated carefully. But it also has many very useful debug functions for userspace. With this option we can have same configuration for system with need of debugfs and a way to turn it off. This gives a extra protection for exposure on systems where user-space services with system access are attacked. It is controlled by a configurable default value that can be override with a kernel command line parameter. (debugfs=) It can be on or off, but also internally on but not seen from user-space. This no-mount mode do not register a debugfs as filesystem, but client can register their parts in the internal structures. This data can be readed with a debugger or saved with a crashkernel. When it is off clients get EPERM error when accessing the functions for registering their components. Signed-off-by: Peter Enderborg Link: https://lore.kernel.org/r/20200716071511.26864-3-peter.enderborg@sony.com Signed-off-by: Greg Kroah-Hartman --- fs/debugfs/inode.c | 39 +++++++++++++++++++++++++++++++++++++++ fs/debugfs/internal.h | 14 ++++++++++++++ 2 files changed, 53 insertions(+) (limited to 'fs/debugfs') diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c index b7f2e971ecbc..2fcf66473436 100644 --- a/fs/debugfs/inode.c +++ b/fs/debugfs/inode.c @@ -35,6 +35,7 @@ static struct vfsmount *debugfs_mount; static int debugfs_mount_count; static bool debugfs_registered; +static unsigned int debugfs_allow = DEFAULT_DEBUGFS_ALLOW_BITS; /* * Don't allow access attributes to be changed whilst the kernel is locked down @@ -266,6 +267,9 @@ static struct dentry *debug_mount(struct file_system_type *fs_type, int flags, const char *dev_name, void *data) { + if (!(debugfs_allow & DEBUGFS_ALLOW_API)) + return ERR_PTR(-EPERM); + return mount_single(fs_type, flags, data, debug_fill_super); } @@ -311,6 +315,9 @@ static struct dentry *start_creating(const char *name, struct dentry *parent) struct dentry *dentry; int error; + if (!(debugfs_allow & DEBUGFS_ALLOW_API)) + return ERR_PTR(-EPERM); + pr_debug("creating file '%s'\n", name); if (IS_ERR(parent)) @@ -385,6 +392,11 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode, if (IS_ERR(dentry)) return dentry; + if (!(debugfs_allow & DEBUGFS_ALLOW_API)) { + failed_creating(dentry); + return ERR_PTR(-EPERM); + } + inode = debugfs_get_inode(dentry->d_sb); if (unlikely(!inode)) { pr_err("out of free dentries, can not create file '%s'\n", @@ -541,6 +553,11 @@ struct dentry *debugfs_create_dir(const char *name, struct dentry *parent) if (IS_ERR(dentry)) return dentry; + if (!(debugfs_allow & DEBUGFS_ALLOW_API)) { + failed_creating(dentry); + return ERR_PTR(-EPERM); + } + inode = debugfs_get_inode(dentry->d_sb); if (unlikely(!inode)) { pr_err("out of free dentries, can not create directory '%s'\n", @@ -583,6 +600,11 @@ struct dentry *debugfs_create_automount(const char *name, if (IS_ERR(dentry)) return dentry; + if (!(debugfs_allow & DEBUGFS_ALLOW_API)) { + failed_creating(dentry); + return ERR_PTR(-EPERM); + } + inode = debugfs_get_inode(dentry->d_sb); if (unlikely(!inode)) { pr_err("out of free dentries, can not create automount '%s'\n", @@ -786,10 +808,27 @@ bool debugfs_initialized(void) } EXPORT_SYMBOL_GPL(debugfs_initialized); +static int __init debugfs_kernel(char *str) +{ + if (str) { + if (!strcmp(str, "on")) + debugfs_allow = DEBUGFS_ALLOW_API | DEBUGFS_ALLOW_MOUNT; + else if (!strcmp(str, "no-mount")) + debugfs_allow = DEBUGFS_ALLOW_API; + else if (!strcmp(str, "off")) + debugfs_allow = 0; + } + + return 0; +} +early_param("debugfs", debugfs_kernel); static int __init debugfs_init(void) { int retval; + if (!(debugfs_allow & DEBUGFS_ALLOW_MOUNT)) + return -EPERM; + retval = sysfs_create_mount_point(kernel_kobj, "debug"); if (retval) return retval; diff --git a/fs/debugfs/internal.h b/fs/debugfs/internal.h index 034e6973cead..92af8ae31313 100644 --- a/fs/debugfs/internal.h +++ b/fs/debugfs/internal.h @@ -29,4 +29,18 @@ struct debugfs_fsdata { */ #define DEBUGFS_FSDATA_IS_REAL_FOPS_BIT BIT(0) +/* Access BITS */ +#define DEBUGFS_ALLOW_API BIT(0) +#define DEBUGFS_ALLOW_MOUNT BIT(1) + +#ifdef CONFIG_DEBUG_FS_ALLOW_ALL +#define DEFAULT_DEBUGFS_ALLOW_BITS (DEBUGFS_ALLOW_MOUNT | DEBUGFS_ALLOW_API) +#endif +#ifdef CONFIG_DEBUG_FS_DISALLOW_MOUNT +#define DEFAULT_DEBUGFS_ALLOW_BITS (DEBUGFS_ALLOW_API) +#endif +#ifdef CONFIG_DEBUG_FS_ALLOW_NONE +#define DEFAULT_DEBUGFS_ALLOW_BITS (0) +#endif + #endif /* _DEBUGFS_INTERNAL_H_ */ -- cgit