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| author | Eric Paris <eparis@redhat.com> | 2010-10-28 23:21:57 +0200 |
|---|---|---|
| committer | Eric Paris <eparis@redhat.com> | 2010-10-28 23:22:14 +0200 |
| commit | e7099d8a5a34d2876908a9fab4952dabdcfc5909 (patch) | |
| tree | 34f62d8ae23c4c115a0b615cd13e9ae7ddd28b42 | |
| parent | fanotify: allow userspace to override max queue depth (diff) | |
| download | linux-e7099d8a5a34d2876908a9fab4952dabdcfc5909.tar.xz linux-e7099d8a5a34d2876908a9fab4952dabdcfc5909.zip | |
fanotify: limit the number of marks in a single fanotify group
There is currently no limit on the number of marks a given fanotify group
can have. Since fanotify is gated on CAP_SYS_ADMIN this was not seen as
a serious DoS threat. This patch implements a default of 8192, the same as
inotify to work towards removing the CAP_SYS_ADMIN gating and eliminating
the default DoS'able status.
Signed-off-by: Eric Paris <eparis@redhat.com>
| -rw-r--r-- | fs/notify/fanotify/fanotify_user.c | 9 | ||||
| -rw-r--r-- | include/linux/fsnotify_backend.h | 1 |
2 files changed, 10 insertions, 0 deletions
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index 43d66d9b2eff..1d33d7db277a 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -17,6 +17,7 @@ #include <asm/ioctls.h> #define FANOTIFY_DEFAULT_MAX_EVENTS 16384 +#define FANOTIFY_DEFAULT_MAX_MARKS 8192 extern const struct fsnotify_ops fanotify_fsnotify_ops; @@ -584,6 +585,9 @@ static int fanotify_add_vfsmount_mark(struct fsnotify_group *group, if (!fsn_mark) { int ret; + if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks) + return -ENOSPC; + fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); if (!fsn_mark) return -ENOMEM; @@ -626,6 +630,9 @@ static int fanotify_add_inode_mark(struct fsnotify_group *group, if (!fsn_mark) { int ret; + if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks) + return -ENOSPC; + fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); if (!fsn_mark) return -ENOMEM; @@ -700,6 +707,8 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) group->max_events = FANOTIFY_DEFAULT_MAX_EVENTS; } + group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS; + fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags); if (fd < 0) goto out_put_group; diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h index b37f3a71a9dc..49ceed6e92b1 100644 --- a/include/linux/fsnotify_backend.h +++ b/include/linux/fsnotify_backend.h @@ -169,6 +169,7 @@ struct fsnotify_group { bool bypass_perm; /* protected by access_mutex */ #endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */ int f_flags; + unsigned int max_marks; } fanotify_data; #endif /* CONFIG_FANOTIFY */ }; |