diff options
| -rw-r--r-- | fs/proc/base.c | 84 |
1 files changed, 77 insertions, 7 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index 23db452ab42..fb34f88a4a7 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -340,6 +340,52 @@ static int proc_root_link(struct inode *inode, struct dentry **dentry, struct vf return result; } + +/* Same as proc_root_link, but this addionally tries to get fs from other + * threads in the group */ +static int proc_task_root_link(struct inode *inode, struct dentry **dentry, struct vfsmount **mnt) +{ + struct fs_struct *fs; + int result = -ENOENT; + struct task_struct *leader = proc_task(inode); + + task_lock(leader); + fs = leader->fs; + if (fs) { + atomic_inc(&fs->count); + task_unlock(leader); + } else { + /* Try to get fs from other threads */ + task_unlock(leader); + struct task_struct *task = leader; + read_lock(&tasklist_lock); + if (pid_alive(task)) { + while ((task = next_thread(task)) != leader) { + task_lock(task); + fs = task->fs; + if (fs) { + atomic_inc(&fs->count); + task_unlock(task); + break; + } + task_unlock(task); + } + } + read_unlock(&tasklist_lock); + } + + if (fs) { + read_lock(&fs->lock); + *mnt = mntget(fs->rootmnt); + *dentry = dget(fs->root); + read_unlock(&fs->lock); + result = 0; + put_fs_struct(fs); + } + return result; +} + + #define MAY_PTRACE(task) \ (task == current || \ (task->parent == current && \ @@ -471,14 +517,14 @@ static int proc_oom_score(struct task_struct *task, char *buffer) /* permission checks */ -static int proc_check_root(struct inode *inode) +/* If the process being read is separated by chroot from the reading process, + * don't let the reader access the threads. + */ +static int proc_check_chroot(struct dentry *root, struct vfsmount *vfsmnt) { - struct dentry *de, *base, *root; - struct vfsmount *our_vfsmnt, *vfsmnt, *mnt; + struct dentry *de, *base; + struct vfsmount *our_vfsmnt, *mnt; int res = 0; - - if (proc_root_link(inode, &root, &vfsmnt)) /* Ewww... */ - return -ENOENT; read_lock(¤t->fs->lock); our_vfsmnt = mntget(current->fs->rootmnt); base = dget(current->fs->root); @@ -511,6 +557,16 @@ out: goto exit; } +static int proc_check_root(struct inode *inode) +{ + struct dentry *root; + struct vfsmount *vfsmnt; + + if (proc_root_link(inode, &root, &vfsmnt)) /* Ewww... */ + return -ENOENT; + return proc_check_chroot(root, vfsmnt); +} + static int proc_permission(struct inode *inode, int mask, struct nameidata *nd) { if (generic_permission(inode, mask, NULL) != 0) @@ -518,6 +574,20 @@ static int proc_permission(struct inode *inode, int mask, struct nameidata *nd) return proc_check_root(inode); } +static int proc_task_permission(struct inode *inode, int mask, struct nameidata *nd) +{ + struct dentry *root; + struct vfsmount *vfsmnt; + + if (generic_permission(inode, mask, NULL) != 0) + return -EACCES; + + if (proc_task_root_link(inode, &root, &vfsmnt)) + return -ENOENT; + + return proc_check_chroot(root, vfsmnt); +} + extern struct seq_operations proc_pid_maps_op; static int maps_open(struct inode *inode, struct file *file) { @@ -1419,7 +1489,7 @@ static struct inode_operations proc_fd_inode_operations = { static struct inode_operations proc_task_inode_operations = { .lookup = proc_task_lookup, - .permission = proc_permission, + .permission = proc_task_permission, }; #ifdef CONFIG_SECURITY |