diff options
Diffstat (limited to 'fs/notify/fanotify/fanotify_user.c')
| -rw-r--r-- | fs/notify/fanotify/fanotify_user.c | 239 |
1 files changed, 238 insertions, 1 deletions
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index 55d6e379f2b..bc4fa48157f 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -1,12 +1,18 @@ #include <linux/fcntl.h> +#include <linux/file.h> #include <linux/fs.h> #include <linux/anon_inodes.h> #include <linux/fsnotify_backend.h> +#include <linux/init.h> +#include <linux/namei.h> #include <linux/security.h> #include <linux/syscalls.h> +#include <linux/types.h> #include "fanotify.h" +static struct kmem_cache *fanotify_mark_cache __read_mostly; + static int fanotify_release(struct inode *ignored, struct file *file) { struct fsnotify_group *group = file->private_data; @@ -28,6 +34,185 @@ static const struct file_operations fanotify_fops = { .compat_ioctl = NULL, }; +static void fanotify_free_mark(struct fsnotify_mark *fsn_mark) +{ + kmem_cache_free(fanotify_mark_cache, fsn_mark); +} + +static int fanotify_find_path(int dfd, const char __user *filename, + struct path *path, unsigned int flags) +{ + int ret; + + pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__, + dfd, filename, flags); + + if (filename == NULL) { + struct file *file; + int fput_needed; + + ret = -EBADF; + file = fget_light(dfd, &fput_needed); + if (!file) + goto out; + + ret = -ENOTDIR; + if ((flags & FAN_MARK_ONLYDIR) && + !(S_ISDIR(file->f_path.dentry->d_inode->i_mode))) { + fput_light(file, fput_needed); + goto out; + } + + *path = file->f_path; + path_get(path); + fput_light(file, fput_needed); + } else { + unsigned int lookup_flags = 0; + + if (!(flags & FAN_MARK_DONT_FOLLOW)) + lookup_flags |= LOOKUP_FOLLOW; + if (flags & FAN_MARK_ONLYDIR) + lookup_flags |= LOOKUP_DIRECTORY; + + ret = user_path_at(dfd, filename, lookup_flags, path); + if (ret) + goto out; + } + + /* you can only watch an inode if you have read permissions on it */ + ret = inode_permission(path->dentry->d_inode, MAY_READ); + if (ret) + path_put(path); +out: + return ret; +} + +static int fanotify_remove_mark(struct fsnotify_group *group, + struct inode *inode, + __u32 mask) +{ + struct fsnotify_mark *fsn_mark; + __u32 new_mask; + + pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, + group, inode, mask); + + fsn_mark = fsnotify_find_mark(group, inode); + if (!fsn_mark) + return -ENOENT; + + spin_lock(&fsn_mark->lock); + fsn_mark->mask &= ~mask; + new_mask = fsn_mark->mask; + spin_unlock(&fsn_mark->lock); + + if (!new_mask) + fsnotify_destroy_mark(fsn_mark); + else + fsnotify_recalc_inode_mask(inode); + + fsnotify_recalc_group_mask(group); + + /* matches the fsnotify_find_mark() */ + fsnotify_put_mark(fsn_mark); + + return 0; +} + +static int fanotify_add_mark(struct fsnotify_group *group, + struct inode *inode, + __u32 mask) +{ + struct fsnotify_mark *fsn_mark; + __u32 old_mask, new_mask; + int ret; + + pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, + group, inode, mask); + + fsn_mark = fsnotify_find_mark(group, inode); + if (!fsn_mark) { + struct fsnotify_mark *new_fsn_mark; + + ret = -ENOMEM; + new_fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); + if (!new_fsn_mark) + goto out; + + fsnotify_init_mark(new_fsn_mark, fanotify_free_mark); + ret = fsnotify_add_mark(new_fsn_mark, group, inode, 0); + if (ret) { + fanotify_free_mark(new_fsn_mark); + goto out; + } + + fsn_mark = new_fsn_mark; + } + + ret = 0; + + spin_lock(&fsn_mark->lock); + old_mask = fsn_mark->mask; + fsn_mark->mask |= mask; + new_mask = fsn_mark->mask; + spin_unlock(&fsn_mark->lock); + + /* we made changes to a mask, update the group mask and the inode mask + * so things happen quickly. */ + if (old_mask != new_mask) { + /* more bits in old than in new? */ + int dropped = (old_mask & ~new_mask); + /* more bits in this mark than the inode's mask? */ + int do_inode = (new_mask & ~inode->i_fsnotify_mask); + /* more bits in this mark than the group? */ + int do_group = (new_mask & ~group->mask); + + /* update the inode with this new mark */ + if (dropped || do_inode) + fsnotify_recalc_inode_mask(inode); + + /* update the group mask with the new mask */ + if (dropped || do_group) + fsnotify_recalc_group_mask(group); + } + + /* match the init or the find.... */ + fsnotify_put_mark(fsn_mark); +out: + return ret; +} + +static int fanotify_update_mark(struct fsnotify_group *group, + struct inode *inode, int flags, + __u32 mask) +{ + pr_debug("%s: group=%p inode=%p flags=%x mask=%x\n", __func__, + group, inode, flags, mask); + + if (flags & FAN_MARK_ADD) + fanotify_add_mark(group, inode, mask); + else if (flags & FAN_MARK_REMOVE) + fanotify_remove_mark(group, inode, mask); + else + BUG(); + + return 0; +} + +static bool fanotify_mark_validate_input(int flags, + __u32 mask) +{ + pr_debug("%s: flags=%x mask=%x\n", __func__, flags, mask); + + /* are flags valid of this operation? */ + if (!fanotify_mark_flags_valid(flags)) + return false; + /* is the mask valid? */ + if (!fanotify_mask_valid(mask)) + return false; + return true; +} + /* fanotify syscalls */ SYSCALL_DEFINE3(fanotify_init, unsigned int, flags, unsigned int, event_f_flags, unsigned int, priority) @@ -74,5 +259,57 @@ out_put_group: SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags, __u64, mask, int, dfd, const char __user *, pathname) { - return -ENOSYS; + struct inode *inode; + struct fsnotify_group *group; + struct file *filp; + struct path path; + int ret, fput_needed; + + pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n", + __func__, fanotify_fd, flags, dfd, pathname, mask); + + /* we only use the lower 32 bits as of right now. */ + if (mask & ((__u64)0xffffffff << 32)) + return -EINVAL; + + if (!fanotify_mark_validate_input(flags, mask)) + return -EINVAL; + + filp = fget_light(fanotify_fd, &fput_needed); + if (unlikely(!filp)) + return -EBADF; + + /* verify that this is indeed an fanotify instance */ + ret = -EINVAL; + if (unlikely(filp->f_op != &fanotify_fops)) + goto fput_and_out; + + ret = fanotify_find_path(dfd, pathname, &path, flags); + if (ret) + goto fput_and_out; + + /* inode held in place by reference to path; group by fget on fd */ + inode = path.dentry->d_inode; + group = filp->private_data; + + /* create/update an inode mark */ + ret = fanotify_update_mark(group, inode, flags, mask); + + path_put(&path); +fput_and_out: + fput_light(filp, fput_needed); + return ret; +} + +/* + * fanotify_user_setup - Our initialization function. Note that we cannnot return + * error because we have compiled-in VFS hooks. So an (unlikely) failure here + * must result in panic(). + */ +static int __init fanotify_user_setup(void) +{ + fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC); + + return 0; } +device_initcall(fanotify_user_setup); |