diff options
Diffstat (limited to 'fs/debugfs/inode.c')
| -rw-r--r-- | fs/debugfs/inode.c | 151 |
1 files changed, 121 insertions, 30 deletions
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c index e742dfc66933..2e8e112b1993 100644 --- a/fs/debugfs/inode.c +++ b/fs/debugfs/inode.c @@ -35,19 +35,24 @@ static struct vfsmount *debugfs_mount; static int debugfs_mount_count; static bool debugfs_registered; +static unsigned int debugfs_allow __ro_after_init = DEFAULT_DEBUGFS_ALLOW_BITS; /* * Don't allow access attributes to be changed whilst the kernel is locked down * so that we can use the file mode as part of a heuristic to determine whether * to lock down individual files. */ -static int debugfs_setattr(struct dentry *dentry, struct iattr *ia) +static int debugfs_setattr(struct user_namespace *mnt_userns, + struct dentry *dentry, struct iattr *ia) { - int ret = security_locked_down(LOCKDOWN_DEBUGFS); + int ret; - if (ret && (ia->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))) - return ret; - return simple_setattr(dentry, ia); + if (ia->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)) { + ret = security_locked_down(LOCKDOWN_DEBUGFS); + if (ret) + return ret; + } + return simple_setattr(&init_user_ns, dentry, ia); } static const struct inode_operations debugfs_file_inode_operations = { @@ -77,6 +82,8 @@ struct debugfs_mount_opts { kuid_t uid; kgid_t gid; umode_t mode; + /* Opt_* bitfield. */ + unsigned int opts; }; enum { @@ -106,6 +113,7 @@ static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts) kgid_t gid; char *p; + opts->opts = 0; opts->mode = DEBUGFS_DEFAULT_MODE; while ((p = strsep(&data, ",")) != NULL) { @@ -140,24 +148,44 @@ static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts) * but traditionally debugfs has ignored all mount options */ } + + opts->opts |= BIT(token); } return 0; } -static int debugfs_apply_options(struct super_block *sb) +static void _debugfs_apply_options(struct super_block *sb, bool remount) { struct debugfs_fs_info *fsi = sb->s_fs_info; struct inode *inode = d_inode(sb->s_root); struct debugfs_mount_opts *opts = &fsi->mount_opts; - inode->i_mode &= ~S_IALLUGO; - inode->i_mode |= opts->mode; + /* + * On remount, only reset mode/uid/gid if they were provided as mount + * options. + */ - inode->i_uid = opts->uid; - inode->i_gid = opts->gid; + if (!remount || opts->opts & BIT(Opt_mode)) { + inode->i_mode &= ~S_IALLUGO; + inode->i_mode |= opts->mode; + } - return 0; + if (!remount || opts->opts & BIT(Opt_uid)) + inode->i_uid = opts->uid; + + if (!remount || opts->opts & BIT(Opt_gid)) + inode->i_gid = opts->gid; +} + +static void debugfs_apply_options(struct super_block *sb) +{ + _debugfs_apply_options(sb, false); +} + +static void debugfs_apply_options_remount(struct super_block *sb) +{ + _debugfs_apply_options(sb, true); } static int debugfs_remount(struct super_block *sb, int *flags, char *data) @@ -170,7 +198,7 @@ static int debugfs_remount(struct super_block *sb, int *flags, char *data) if (err) goto fail; - debugfs_apply_options(sb); + debugfs_apply_options_remount(sb); fail: return err; @@ -266,6 +294,9 @@ 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); } @@ -293,7 +324,7 @@ struct dentry *debugfs_lookup(const char *name, struct dentry *parent) { struct dentry *dentry; - if (IS_ERR(parent)) + if (!debugfs_initialized() || IS_ERR_OR_NULL(name) || IS_ERR(parent)) return NULL; if (!parent) @@ -311,6 +342,12 @@ 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); + + if (!debugfs_initialized()) + return ERR_PTR(-ENOENT); + pr_debug("creating file '%s'\n", name); if (IS_ERR(parent)) @@ -385,6 +422,11 @@ 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", @@ -431,6 +473,11 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode, * * If debugfs is not enabled in the kernel, the value -%ENODEV will be * returned. + * + * NOTE: it's expected that most callers should _ignore_ the errors returned + * by this function. Other debugfs functions handle the fact that the "dentry" + * passed to them could be an error and they don't crash in that case. + * Drivers should generally work fine even if debugfs fails to init anyway. */ struct dentry *debugfs_create_file(const char *name, umode_t mode, struct dentry *parent, void *data, @@ -501,26 +548,16 @@ EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe); * wide range of flexibility in creating a file, or a directory (if you want * to create a directory, the debugfs_create_dir() function is * recommended to be used instead.) - * - * 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 - * to be removed (no automatic cleanup happens if your module is unloaded, - * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be - * returned. - * - * If debugfs is not enabled in the kernel, the value -%ENODEV will be - * returned. */ -struct dentry *debugfs_create_file_size(const char *name, umode_t mode, - struct dentry *parent, void *data, - const struct file_operations *fops, - loff_t file_size) +void debugfs_create_file_size(const char *name, umode_t mode, + struct dentry *parent, void *data, + const struct file_operations *fops, + loff_t file_size) { struct dentry *de = debugfs_create_file(name, mode, parent, data, fops); - if (de) + if (!IS_ERR(de)) d_inode(de)->i_size = file_size; - return de; } EXPORT_SYMBOL_GPL(debugfs_create_file_size); @@ -542,6 +579,11 @@ EXPORT_SYMBOL_GPL(debugfs_create_file_size); * * If debugfs is not enabled in the kernel, the value -%ENODEV will be * returned. + * + * NOTE: it's expected that most callers should _ignore_ the errors returned + * by this function. Other debugfs functions handle the fact that the "dentry" + * passed to them could be an error and they don't crash in that case. + * Drivers should generally work fine even if debugfs fails to init anyway. */ struct dentry *debugfs_create_dir(const char *name, struct dentry *parent) { @@ -551,6 +593,11 @@ 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", @@ -593,6 +640,11 @@ 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", @@ -716,6 +768,28 @@ void debugfs_remove(struct dentry *dentry) EXPORT_SYMBOL_GPL(debugfs_remove); /** + * debugfs_lookup_and_remove - lookup a directory or file and recursively remove it + * @name: a pointer to a string containing the name of the item to look up. + * @parent: a pointer to the parent dentry of the item. + * + * This is the equlivant of doing something like + * debugfs_remove(debugfs_lookup(..)) but with the proper reference counting + * handled for the directory being looked up. + */ +void debugfs_lookup_and_remove(const char *name, struct dentry *parent) +{ + struct dentry *dentry; + + dentry = debugfs_lookup(name, parent); + if (!dentry) + return; + + debugfs_remove(dentry); + dput(dentry); +} +EXPORT_SYMBOL_GPL(debugfs_lookup_and_remove); + +/** * debugfs_rename - rename a file/directory in the debugfs filesystem * @old_dir: a pointer to the parent dentry for the renamed object. This * should be a directory dentry. @@ -763,8 +837,8 @@ struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry, take_dentry_name_snapshot(&old_name, old_dentry); - error = simple_rename(d_inode(old_dir), old_dentry, d_inode(new_dir), - dentry, 0); + error = simple_rename(&init_user_ns, d_inode(old_dir), old_dentry, + d_inode(new_dir), dentry, 0); if (error) { release_dentry_name_snapshot(&old_name); goto exit; @@ -796,10 +870,27 @@ 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; |