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authorSripathi Kodi <sripathik@in.ibm.com>2005-09-19 18:26:12 -0500
committerLinus Torvalds <torvalds@g5.osdl.org>2005-09-21 09:15:34 -0700
commit66dcca062847bcd261ebb3ac96d51101f31a8630 (patch)
tree12f23a499ae0af8107d0c4a3afcff75e6697fa3b
parentd79e743e9fcf03f521300a970eb1ab69641910ba (diff)
[PATCH] Fix invisible threads problem
When the main thread of a thread group has done pthread_exit() and died, the other threads are still happily running, but will not be visible under /proc because their leader is no longer accessible. This fixes the access control so that we can see the sub-threads again. Signed-off-by: Sripathi Kodi <sripathik@in.ibm.com> Acked-by: Al Viro <viro@ftp.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--fs/proc/base.c84
1 files changed, 77 insertions, 7 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 23db452ab428..fb34f88a4a74 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(&current->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