From bbb9560c0e8746ff53b2f80844ecf1531557eeac Mon Sep 17 00:00:00 2001 From: Daniel Rosenberg Date: Wed, 13 Apr 2016 16:38:34 -0700 Subject: [PATCH] sdcardfs: override umask on mkdir and create The mode on files created on the lower fs should not be affected by the umask of the calling task's fs_struct. Instead, we create a copy and modify it as needed. This also lets us avoid the string shenanigans around .nomedia files. Bug: 27992761 Change-Id: Ia3a6e56c24c6e19b3b01c1827e46403bb71c2f4c Signed-off-by: Daniel Rosenberg --- fs/fs_struct.c | 1 + fs/sdcardfs/inode.c | 70 ++++++++++++++++++++++----------------------- 2 files changed, 36 insertions(+), 35 deletions(-) diff --git a/fs/fs_struct.c b/fs/fs_struct.c index d8ac61d0c932..5a1bb8242a56 100644 --- a/fs/fs_struct.c +++ b/fs/fs_struct.c @@ -127,6 +127,7 @@ struct fs_struct *copy_fs_struct(struct fs_struct *old) } return fs; } +EXPORT_SYMBOL_GPL(copy_fs_struct); int unshare_fs_struct(void) { diff --git a/fs/sdcardfs/inode.c b/fs/sdcardfs/inode.c index 0f4aa17645d6..0b2abbfbf1e0 100755 --- a/fs/sdcardfs/inode.c +++ b/fs/sdcardfs/inode.c @@ -19,6 +19,7 @@ */ #include "sdcardfs.h" +#include /* Do not directly use this function. Use OVERRIDE_CRED() instead. */ const struct cred * override_fsids(struct sdcardfs_sb_info* sbi) @@ -56,6 +57,8 @@ static int sdcardfs_create(struct inode *dir, struct dentry *dentry, struct dentry *lower_parent_dentry = NULL; struct path lower_path; const struct cred *saved_cred = NULL; + struct fs_struct *saved_fs; + struct fs_struct *copied_fs; if(!check_caller_access_to_name(dir, dentry->d_name.name)) { printk(KERN_INFO "%s: need to check the caller's gid in packages.list\n" @@ -74,6 +77,16 @@ static int sdcardfs_create(struct inode *dir, struct dentry *dentry, /* set last 16bytes of mode field to 0664 */ mode = (mode & S_IFMT) | 00664; + + /* temporarily change umask for lower fs write */ + saved_fs = current->fs; + copied_fs = copy_fs_struct(current->fs); + if (!copied_fs) { + err = -ENOMEM; + goto out_unlock; + } + current->fs = copied_fs; + current->fs->umask = 0; err = vfs_create(lower_parent_dentry->d_inode, lower_dentry, mode, want_excl); if (err) goto out; @@ -85,6 +98,9 @@ static int sdcardfs_create(struct inode *dir, struct dentry *dentry, fsstack_copy_inode_size(dir, lower_parent_dentry->d_inode); out: + current->fs = saved_fs; + free_fs_struct(copied_fs); +out_unlock: unlock_dir(lower_parent_dentry); sdcardfs_put_lower_path(dentry, &lower_path); REVERT_CRED(saved_cred); @@ -245,11 +261,9 @@ static int sdcardfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode struct sdcardfs_sb_info *sbi = SDCARDFS_SB(dentry->d_sb); const struct cred *saved_cred = NULL; struct sdcardfs_inode_info *pi = SDCARDFS_I(dir); - char *page_buf; - char *nomedia_dir_name; - char *nomedia_fullpath; - int fullpath_namelen; int touch_err = 0; + struct fs_struct *saved_fs; + struct fs_struct *copied_fs; if(!check_caller_access_to_name(dir, dentry->d_name.name)) { printk(KERN_INFO "%s: need to check the caller's gid in packages.list\n" @@ -276,6 +290,16 @@ static int sdcardfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode /* set last 16bytes of mode field to 0775 */ mode = (mode & S_IFMT) | 00775; + + /* temporarily change umask for lower fs write */ + saved_fs = current->fs; + copied_fs = copy_fs_struct(current->fs); + if (!copied_fs) { + err = -ENOMEM; + goto out_unlock; + } + current->fs = copied_fs; + current->fs->umask = 0; err = vfs_mkdir(lower_parent_dentry->d_inode, lower_dentry, mode); if (err) @@ -316,42 +340,18 @@ static int sdcardfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode /* When creating /Android/data and /Android/obb, mark them as .nomedia */ if (make_nomedia_in_obb || ((pi->perm == PERM_ANDROID) && (!strcasecmp(dentry->d_name.name, "data")))) { - - page_buf = (char *)__get_free_page(GFP_KERNEL); - if (!page_buf) { - printk(KERN_ERR "sdcardfs: failed to allocate page buf\n"); - goto out; - } - - nomedia_dir_name = d_absolute_path(&lower_path, page_buf, PAGE_SIZE); - if (IS_ERR(nomedia_dir_name)) { - free_page((unsigned long)page_buf); - printk(KERN_ERR "sdcardfs: failed to get .nomedia dir name\n"); - goto out; - } - - fullpath_namelen = page_buf + PAGE_SIZE - nomedia_dir_name - 1; - fullpath_namelen += strlen("/.nomedia"); - nomedia_fullpath = kzalloc(fullpath_namelen + 1, GFP_KERNEL); - if (!nomedia_fullpath) { - free_page((unsigned long)page_buf); - printk(KERN_ERR "sdcardfs: failed to allocate .nomedia fullpath buf\n"); - goto out; - } - - strcpy(nomedia_fullpath, nomedia_dir_name); - free_page((unsigned long)page_buf); - strcat(nomedia_fullpath, "/.nomedia"); - touch_err = touch(nomedia_fullpath, 0664); + set_fs_pwd(current->fs, &lower_path); + touch_err = touch(".nomedia", 0664); if (touch_err) { - printk(KERN_ERR "sdcardfs: failed to touch(%s): %d\n", - nomedia_fullpath, touch_err); - kfree(nomedia_fullpath); + printk(KERN_ERR "sdcardfs: failed to create .nomedia in %s: %d\n", + lower_path.dentry->d_name.name, touch_err); goto out; } - kfree(nomedia_fullpath); } out: + current->fs = saved_fs; + free_fs_struct(copied_fs); +out_unlock: unlock_dir(lower_parent_dentry); sdcardfs_put_lower_path(dentry, &lower_path); out_revert: