CRED: Use RCU to access another task's creds and to release a task's own creds

[deliverable/linux.git] / fs / proc / base.c

diff --git a/fs/proc/base.c b/fs/proc/base.c
index a28840b11b89b5ca0b544f44ce58182544f51eef..cf42c42cbfbbf5db12491dc769585f4a0c7f4229 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -148,9 +148,6 @@ static unsigned int pid_entry_count_dirs(const struct pid_entry *entries,
        return count;
 }
 
-int maps_protect;
-EXPORT_SYMBOL(maps_protect);
-
 static struct fs_struct *get_fs_struct(struct task_struct *task)
 {
        struct fs_struct *fs;
@@ -164,7 +161,6 @@ static struct fs_struct *get_fs_struct(struct task_struct *task)
 
 static int get_nr_threads(struct task_struct *tsk)
 {
-       /* Must be called with the rcu_read_lock held */
        unsigned long flags;
        int count = 0;
 
@@ -471,14 +467,10 @@ static int proc_pid_limits(struct task_struct *task, char *buffer)
 
        struct rlimit rlim[RLIM_NLIMITS];
 
-       rcu_read_lock();
-       if (!lock_task_sighand(task,&flags)) {
-               rcu_read_unlock();
+       if (!lock_task_sighand(task, &flags))
                return 0;
-       }
        memcpy(rlim, task->signal->rlim, sizeof(struct rlimit) * RLIM_NLIMITS);
        unlock_task_sighand(task, &flags);
-       rcu_read_unlock();
 
        /*
         * print the file header
@@ -1414,6 +1406,7 @@ static struct inode *proc_pid_make_inode(struct super_block * sb, struct task_st
 {
        struct inode * inode;
        struct proc_inode *ei;
+       const struct cred *cred;
 
        /* We need a new inode */
 
@@ -1436,8 +1429,11 @@ static struct inode *proc_pid_make_inode(struct super_block * sb, struct task_st
        inode->i_uid = 0;
        inode->i_gid = 0;
        if (task_dumpable(task)) {
-               inode->i_uid = task->euid;
-               inode->i_gid = task->egid;
+               rcu_read_lock();
+               cred = __task_cred(task);
+               inode->i_uid = cred->euid;
+               inode->i_gid = cred->egid;
+               rcu_read_unlock();
        }
        security_task_to_inode(task, inode);
 
@@ -1453,6 +1449,8 @@ static int pid_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat
 {
        struct inode *inode = dentry->d_inode;
        struct task_struct *task;
+       const struct cred *cred;
+
        generic_fillattr(inode, stat);
 
        rcu_read_lock();
@@ -1462,8 +1460,9 @@ static int pid_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat
        if (task) {
                if ((inode->i_mode == (S_IFDIR|S_IRUGO|S_IXUGO)) ||
                    task_dumpable(task)) {
-                       stat->uid = task->euid;
-                       stat->gid = task->egid;
+                       cred = __task_cred(task);
+                       stat->uid = cred->euid;
+                       stat->gid = cred->egid;
                }
        }
        rcu_read_unlock();
@@ -1491,11 +1490,16 @@ static int pid_revalidate(struct dentry *dentry, struct nameidata *nd)
 {
        struct inode *inode = dentry->d_inode;
        struct task_struct *task = get_proc_task(inode);
+       const struct cred *cred;
+
        if (task) {
                if ((inode->i_mode == (S_IFDIR|S_IRUGO|S_IXUGO)) ||
                    task_dumpable(task)) {
-                       inode->i_uid = task->euid;
-                       inode->i_gid = task->egid;
+                       rcu_read_lock();
+                       cred = __task_cred(task);
+                       inode->i_uid = cred->euid;
+                       inode->i_gid = cred->egid;
+                       rcu_read_unlock();
                } else {
                        inode->i_uid = 0;
                        inode->i_gid = 0;
@@ -1657,6 +1661,7 @@ static int tid_fd_revalidate(struct dentry *dentry, struct nameidata *nd)
        struct task_struct *task = get_proc_task(inode);
        int fd = proc_fd(inode);
        struct files_struct *files;
+       const struct cred *cred;
 
        if (task) {
                files = get_files_struct(task);
@@ -1666,8 +1671,11 @@ static int tid_fd_revalidate(struct dentry *dentry, struct nameidata *nd)
                                rcu_read_unlock();
                                put_files_struct(files);
                                if (task_dumpable(task)) {
-                                       inode->i_uid = task->euid;
-                                       inode->i_gid = task->egid;
+                                       rcu_read_lock();
+                                       cred = __task_cred(task);
+                                       inode->i_uid = cred->euid;
+                                       inode->i_gid = cred->egid;
+                                       rcu_read_unlock();
                                } else {
                                        inode->i_uid = 0;
                                        inode->i_gid = 0;
@@ -1720,9 +1728,9 @@ static struct dentry *proc_fd_instantiate(struct inode *dir,
        file = fcheck_files(files, fd);
        if (!file)
                goto out_unlock;
-       if (file->f_mode & 1)
+       if (file->f_mode & FMODE_READ)
                inode->i_mode |= S_IRUSR | S_IXUSR;
-       if (file->f_mode & 2)
+       if (file->f_mode & FMODE_WRITE)
                inode->i_mode |= S_IWUSR | S_IXUSR;
        spin_unlock(&files->file_lock);
        put_files_struct(files);
@@ -2443,6 +2451,13 @@ static int proc_tgid_io_accounting(struct task_struct *task, char *buffer)
 }
 #endif /* CONFIG_TASK_IO_ACCOUNTING */
 
+static int proc_pid_personality(struct seq_file *m, struct pid_namespace *ns,
+                               struct pid *pid, struct task_struct *task)
+{
+       seq_printf(m, "%08x\n", task->personality);
+       return 0;
+}
+
 /*
  * Thread groups
  */
@@ -2459,6 +2474,7 @@ static const struct pid_entry tgid_base_stuff[] = {
        REG("environ",    S_IRUSR, environ),
        INF("auxv",       S_IRUSR, pid_auxv),
        ONE("status",     S_IRUGO, pid_status),
+       ONE("personality", S_IRUSR, pid_personality),
        INF("limits",     S_IRUSR, pid_limits),
 #ifdef CONFIG_SCHED_DEBUG
        REG("sched",      S_IRUGO|S_IWUSR, pid_sched),
@@ -2794,6 +2810,7 @@ static const struct pid_entry tid_base_stuff[] = {
        REG("environ",   S_IRUSR, environ),
        INF("auxv",      S_IRUSR, pid_auxv),
        ONE("status",    S_IRUGO, pid_status),
+       ONE("personality", S_IRUSR, pid_personality),
        INF("limits",    S_IRUSR, pid_limits),
 #ifdef CONFIG_SCHED_DEBUG
        REG("sched",     S_IRUGO|S_IWUSR, pid_sched),
@@ -3088,9 +3105,7 @@ static int proc_task_getattr(struct vfsmount *mnt, struct dentry *dentry, struct
        generic_fillattr(inode, stat);
 
        if (p) {
-               rcu_read_lock();
                stat->nlink += get_nr_threads(p);
-               rcu_read_unlock();
                put_task_struct(p);
        }