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-rw-r--r--fs/debugfs/inode.c149
1 files changed, 148 insertions, 1 deletions
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 956d5ddddf6..b80bc846a15 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -23,9 +23,13 @@
#include <linux/debugfs.h>
#include <linux/fsnotify.h>
#include <linux/string.h>
+#include <linux/seq_file.h>
+#include <linux/parser.h>
#include <linux/magic.h>
#include <linux/slab.h>
+#define DEBUGFS_DEFAULT_MODE 0755
+
static struct vfsmount *debugfs_mount;
static int debugfs_mount_count;
static bool debugfs_registered;
@@ -125,11 +129,154 @@ static inline int debugfs_positive(struct dentry *dentry)
return dentry->d_inode && !d_unhashed(dentry);
}
+struct debugfs_mount_opts {
+ uid_t uid;
+ gid_t gid;
+ umode_t mode;
+};
+
+enum {
+ Opt_uid,
+ Opt_gid,
+ Opt_mode,
+ Opt_err
+};
+
+static const match_table_t tokens = {
+ {Opt_uid, "uid=%u"},
+ {Opt_gid, "gid=%u"},
+ {Opt_mode, "mode=%o"},
+ {Opt_err, NULL}
+};
+
+struct debugfs_fs_info {
+ struct debugfs_mount_opts mount_opts;
+};
+
+static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
+{
+ substring_t args[MAX_OPT_ARGS];
+ int option;
+ int token;
+ char *p;
+
+ opts->mode = DEBUGFS_DEFAULT_MODE;
+
+ while ((p = strsep(&data, ",")) != NULL) {
+ if (!*p)
+ continue;
+
+ token = match_token(p, tokens, args);
+ switch (token) {
+ case Opt_uid:
+ if (match_int(&args[0], &option))
+ return -EINVAL;
+ opts->uid = option;
+ break;
+ case Opt_gid:
+ if (match_octal(&args[0], &option))
+ return -EINVAL;
+ opts->gid = option;
+ break;
+ case Opt_mode:
+ if (match_octal(&args[0], &option))
+ return -EINVAL;
+ opts->mode = option & S_IALLUGO;
+ break;
+ /*
+ * We might like to report bad mount options here;
+ * but traditionally debugfs has ignored all mount options
+ */
+ }
+ }
+
+ return 0;
+}
+
+static int debugfs_apply_options(struct super_block *sb)
+{
+ struct debugfs_fs_info *fsi = sb->s_fs_info;
+ struct inode *inode = sb->s_root->d_inode;
+ struct debugfs_mount_opts *opts = &fsi->mount_opts;
+
+ inode->i_mode &= ~S_IALLUGO;
+ inode->i_mode |= opts->mode;
+
+ inode->i_uid = opts->uid;
+ inode->i_gid = opts->gid;
+
+ return 0;
+}
+
+static int debugfs_remount(struct super_block *sb, int *flags, char *data)
+{
+ int err;
+ struct debugfs_fs_info *fsi = sb->s_fs_info;
+
+ err = debugfs_parse_options(data, &fsi->mount_opts);
+ if (err)
+ goto fail;
+
+ debugfs_apply_options(sb);
+
+fail:
+ return err;
+}
+
+static int debugfs_show_options(struct seq_file *m, struct dentry *root)
+{
+ struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
+ struct debugfs_mount_opts *opts = &fsi->mount_opts;
+
+ if (opts->uid != 0)
+ seq_printf(m, ",uid=%u", opts->uid);
+ if (opts->gid != 0)
+ seq_printf(m, ",gid=%u", opts->gid);
+ if (opts->mode != DEBUGFS_DEFAULT_MODE)
+ seq_printf(m, ",mode=%o", opts->mode);
+
+ return 0;
+}
+
+static const struct super_operations debugfs_super_operations = {
+ .statfs = simple_statfs,
+ .remount_fs = debugfs_remount,
+ .show_options = debugfs_show_options,
+};
+
static int debug_fill_super(struct super_block *sb, void *data, int silent)
{
static struct tree_descr debug_files[] = {{""}};
+ struct debugfs_fs_info *fsi;
+ int err;
+
+ save_mount_options(sb, data);
+
+ fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
+ sb->s_fs_info = fsi;
+ if (!fsi) {
+ err = -ENOMEM;
+ goto fail;
+ }
+
+ err = debugfs_parse_options(data, &fsi->mount_opts);
+ if (err)
+ goto fail;
+
+ err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
+ if (err)
+ goto fail;
+
+ sb->s_op = &debugfs_super_operations;
+
+ debugfs_apply_options(sb);
+
+ return 0;
- return simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
+fail:
+ kfree(fsi);
+ sb->s_fs_info = NULL;
+ return err;
}
static struct dentry *debug_mount(struct file_system_type *fs_type,