next_pidmap: fix overflow condition
[pandora-kernel.git] / fs / proc / base.c
index d49c4b5..dd6628d 100644 (file)
@@ -191,17 +191,20 @@ static int proc_root_link(struct inode *inode, struct path *path)
        return result;
 }
 
-/*
- * Return zero if current may access user memory in @task, -error if not.
- */
-static int check_mem_permission(struct task_struct *task)
+static struct mm_struct *__check_mem_permission(struct task_struct *task)
 {
+       struct mm_struct *mm;
+
+       mm = get_task_mm(task);
+       if (!mm)
+               return ERR_PTR(-EINVAL);
+
        /*
         * A task can always look at itself, in case it chooses
         * to use system calls instead of load instructions.
         */
        if (task == current)
-               return 0;
+               return mm;
 
        /*
         * If current is actively ptrace'ing, and would also be
@@ -213,27 +216,53 @@ static int check_mem_permission(struct task_struct *task)
                match = (tracehook_tracer_task(task) == current);
                rcu_read_unlock();
                if (match && ptrace_may_access(task, PTRACE_MODE_ATTACH))
-                       return 0;
+                       return mm;
        }
 
        /*
-        * Noone else is allowed.
+        * No one else is allowed.
         */
-       return -EPERM;
+       mmput(mm);
+       return ERR_PTR(-EPERM);
+}
+
+/*
+ * If current may access user memory in @task return a reference to the
+ * corresponding mm, otherwise ERR_PTR.
+ */
+static struct mm_struct *check_mem_permission(struct task_struct *task)
+{
+       struct mm_struct *mm;
+       int err;
+
+       /*
+        * Avoid racing if task exec's as we might get a new mm but validate
+        * against old credentials.
+        */
+       err = mutex_lock_killable(&task->signal->cred_guard_mutex);
+       if (err)
+               return ERR_PTR(err);
+
+       mm = __check_mem_permission(task);
+       mutex_unlock(&task->signal->cred_guard_mutex);
+
+       return mm;
 }
 
 struct mm_struct *mm_for_maps(struct task_struct *task)
 {
        struct mm_struct *mm;
+       int err;
 
-       if (mutex_lock_killable(&task->signal->cred_guard_mutex))
-               return NULL;
+       err =  mutex_lock_killable(&task->signal->cred_guard_mutex);
+       if (err)
+               return ERR_PTR(err);
 
        mm = get_task_mm(task);
        if (mm && mm != current->mm &&
                        !ptrace_may_access(task, PTRACE_MODE_READ)) {
                mmput(mm);
-               mm = NULL;
+               mm = ERR_PTR(-EACCES);
        }
        mutex_unlock(&task->signal->cred_guard_mutex);
 
@@ -279,9 +308,9 @@ out:
 
 static int proc_pid_auxv(struct task_struct *task, char *buffer)
 {
-       int res = 0;
-       struct mm_struct *mm = get_task_mm(task);
-       if (mm) {
+       struct mm_struct *mm = mm_for_maps(task);
+       int res = PTR_ERR(mm);
+       if (mm && !IS_ERR(mm)) {
                unsigned int nwords = 0;
                do {
                        nwords += 2;
@@ -318,6 +347,23 @@ static int proc_pid_wchan(struct task_struct *task, char *buffer)
 }
 #endif /* CONFIG_KALLSYMS */
 
+static int lock_trace(struct task_struct *task)
+{
+       int err = mutex_lock_killable(&task->signal->cred_guard_mutex);
+       if (err)
+               return err;
+       if (!ptrace_may_access(task, PTRACE_MODE_ATTACH)) {
+               mutex_unlock(&task->signal->cred_guard_mutex);
+               return -EPERM;
+       }
+       return 0;
+}
+
+static void unlock_trace(struct task_struct *task)
+{
+       mutex_unlock(&task->signal->cred_guard_mutex);
+}
+
 #ifdef CONFIG_STACKTRACE
 
 #define MAX_STACK_TRACE_DEPTH  64
@@ -327,6 +373,7 @@ static int proc_pid_stack(struct seq_file *m, struct pid_namespace *ns,
 {
        struct stack_trace trace;
        unsigned long *entries;
+       int err;
        int i;
 
        entries = kmalloc(MAX_STACK_TRACE_DEPTH * sizeof(*entries), GFP_KERNEL);
@@ -337,15 +384,20 @@ static int proc_pid_stack(struct seq_file *m, struct pid_namespace *ns,
        trace.max_entries       = MAX_STACK_TRACE_DEPTH;
        trace.entries           = entries;
        trace.skip              = 0;
-       save_stack_trace_tsk(task, &trace);
 
-       for (i = 0; i < trace.nr_entries; i++) {
-               seq_printf(m, "[<%p>] %pS\n",
-                          (void *)entries[i], (void *)entries[i]);
+       err = lock_trace(task);
+       if (!err) {
+               save_stack_trace_tsk(task, &trace);
+
+               for (i = 0; i < trace.nr_entries; i++) {
+                       seq_printf(m, "[<%pK>] %pS\n",
+                                  (void *)entries[i], (void *)entries[i]);
+               }
+               unlock_trace(task);
        }
        kfree(entries);
 
-       return 0;
+       return err;
 }
 #endif
 
@@ -508,18 +560,22 @@ static int proc_pid_syscall(struct task_struct *task, char *buffer)
 {
        long nr;
        unsigned long args[6], sp, pc;
+       int res = lock_trace(task);
+       if (res)
+               return res;
 
        if (task_current_syscall(task, &nr, args, 6, &sp, &pc))
-               return sprintf(buffer, "running\n");
-
-       if (nr < 0)
-               return sprintf(buffer, "%ld 0x%lx 0x%lx\n", nr, sp, pc);
-
-       return sprintf(buffer,
+               res = sprintf(buffer, "running\n");
+       else if (nr < 0)
+               res = sprintf(buffer, "%ld 0x%lx 0x%lx\n", nr, sp, pc);
+       else
+               res = sprintf(buffer,
                       "%ld 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx\n",
                       nr,
                       args[0], args[1], args[2], args[3], args[4], args[5],
                       sp, pc);
+       unlock_trace(task);
+       return res;
 }
 #endif /* CONFIG_HAVE_ARCH_TRACEHOOK */
 
@@ -775,18 +831,14 @@ static ssize_t mem_read(struct file * file, char __user * buf,
        if (!task)
                goto out_no_task;
 
-       if (check_mem_permission(task))
-               goto out;
-
        ret = -ENOMEM;
        page = (char *)__get_free_page(GFP_TEMPORARY);
        if (!page)
                goto out;
 
-       ret = 0;
-       mm = get_task_mm(task);
-       if (!mm)
+       mm = check_mem_permission(task);
+       ret = PTR_ERR(mm);
+       if (IS_ERR(mm))
                goto out_free;
 
        ret = -EIO;
@@ -800,8 +852,8 @@ static ssize_t mem_read(struct file * file, char __user * buf,
                int this_len, retval;
 
                this_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
-               retval = access_process_vm(task, src, page, this_len, 0);
-               if (!retval || check_mem_permission(task)) {
+               retval = access_remote_vm(mm, src, page, this_len, 0);
+               if (!retval) {
                        if (!ret)
                                ret = -EIO;
                        break;
@@ -829,10 +881,6 @@ out_no_task:
        return ret;
 }
 
-#define mem_write NULL
-
-#ifndef mem_write
-/* This is a security hazard */
 static ssize_t mem_write(struct file * file, const char __user *buf,
                         size_t count, loff_t *ppos)
 {
@@ -840,18 +888,25 @@ static ssize_t mem_write(struct file * file, const char __user *buf,
        char *page;
        struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode);
        unsigned long dst = *ppos;
+       struct mm_struct *mm;
 
        copied = -ESRCH;
        if (!task)
                goto out_no_task;
 
-       if (check_mem_permission(task))
-               goto out;
+       mm = check_mem_permission(task);
+       copied = PTR_ERR(mm);
+       if (IS_ERR(mm))
+               goto out_task;
+
+       copied = -EIO;
+       if (file->private_data != (void *)((long)current->self_exec_id))
+               goto out_mm;
 
        copied = -ENOMEM;
        page = (char *)__get_free_page(GFP_TEMPORARY);
        if (!page)
-               goto out;
+               goto out_mm;
 
        copied = 0;
        while (count > 0) {
@@ -862,7 +917,7 @@ static ssize_t mem_write(struct file * file, const char __user *buf,
                        copied = -EFAULT;
                        break;
                }
-               retval = access_process_vm(task, dst, page, this_len, 1);
+               retval = access_remote_vm(mm, dst, page, this_len, 1);
                if (!retval) {
                        if (!copied)
                                copied = -EIO;
@@ -875,12 +930,13 @@ static ssize_t mem_write(struct file * file, const char __user *buf,
        }
        *ppos = dst;
        free_page((unsigned long) page);
-out:
+out_mm:
+       mmput(mm);
+out_task:
        put_task_struct(task);
 out_no_task:
        return copied;
 }
-#endif
 
 loff_t mem_lseek(struct file *file, loff_t offset, int orig)
 {
@@ -917,20 +973,18 @@ static ssize_t environ_read(struct file *file, char __user *buf,
        if (!task)
                goto out_no_task;
 
-       if (!ptrace_may_access(task, PTRACE_MODE_READ))
-               goto out;
-
        ret = -ENOMEM;
        page = (char *)__get_free_page(GFP_TEMPORARY);
        if (!page)
                goto out;
 
-       ret = 0;
 
-       mm = get_task_mm(task);
-       if (!mm)
+       mm = mm_for_maps(task);
+       ret = PTR_ERR(mm);
+       if (!mm || IS_ERR(mm))
                goto out_free;
 
+       ret = 0;
        while (count > 0) {
                int this_len, retval, max_len;
 
@@ -2748,8 +2802,12 @@ static int proc_tgid_io_accounting(struct task_struct *task, char *buffer)
 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;
+       int err = lock_trace(task);
+       if (!err) {
+               seq_printf(m, "%08x\n", task->personality);
+               unlock_trace(task);
+       }
+       return err;
 }
 
 /*
@@ -2768,7 +2826,7 @@ static const struct pid_entry tgid_base_stuff[] = {
        REG("environ",    S_IRUSR, proc_environ_operations),
        INF("auxv",       S_IRUSR, proc_pid_auxv),
        ONE("status",     S_IRUGO, proc_pid_status),
-       ONE("personality", S_IRUSR, proc_pid_personality),
+       ONE("personality", S_IRUGO, proc_pid_personality),
        INF("limits",     S_IRUGO, proc_pid_limits),
 #ifdef CONFIG_SCHED_DEBUG
        REG("sched",      S_IRUGO|S_IWUSR, proc_pid_sched_operations),
@@ -2778,7 +2836,7 @@ static const struct pid_entry tgid_base_stuff[] = {
 #endif
        REG("comm",      S_IRUGO|S_IWUSR, proc_pid_set_comm_operations),
 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
-       INF("syscall",    S_IRUSR, proc_pid_syscall),
+       INF("syscall",    S_IRUGO, proc_pid_syscall),
 #endif
        INF("cmdline",    S_IRUGO, proc_pid_cmdline),
        ONE("stat",       S_IRUGO, proc_tgid_stat),
@@ -2797,7 +2855,7 @@ static const struct pid_entry tgid_base_stuff[] = {
 #ifdef CONFIG_PROC_PAGE_MONITOR
        REG("clear_refs", S_IWUSR, proc_clear_refs_operations),
        REG("smaps",      S_IRUGO, proc_smaps_operations),
-       REG("pagemap",    S_IRUSR, proc_pagemap_operations),
+       REG("pagemap",    S_IRUGO, proc_pagemap_operations),
 #endif
 #ifdef CONFIG_SECURITY
        DIR("attr",       S_IRUGO|S_IXUGO, proc_attr_dir_inode_operations, proc_attr_dir_operations),
@@ -2806,7 +2864,7 @@ static const struct pid_entry tgid_base_stuff[] = {
        INF("wchan",      S_IRUGO, proc_pid_wchan),
 #endif
 #ifdef CONFIG_STACKTRACE
-       ONE("stack",      S_IRUSR, proc_pid_stack),
+       ONE("stack",      S_IRUGO, proc_pid_stack),
 #endif
 #ifdef CONFIG_SCHEDSTATS
        INF("schedstat",  S_IRUGO, proc_pid_schedstat),
@@ -3108,14 +3166,14 @@ static const struct pid_entry tid_base_stuff[] = {
        REG("environ",   S_IRUSR, proc_environ_operations),
        INF("auxv",      S_IRUSR, proc_pid_auxv),
        ONE("status",    S_IRUGO, proc_pid_status),
-       ONE("personality", S_IRUSR, proc_pid_personality),
+       ONE("personality", S_IRUGO, proc_pid_personality),
        INF("limits",    S_IRUGO, proc_pid_limits),
 #ifdef CONFIG_SCHED_DEBUG
        REG("sched",     S_IRUGO|S_IWUSR, proc_pid_sched_operations),
 #endif
        REG("comm",      S_IRUGO|S_IWUSR, proc_pid_set_comm_operations),
 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
-       INF("syscall",   S_IRUSR, proc_pid_syscall),
+       INF("syscall",   S_IRUGO, proc_pid_syscall),
 #endif
        INF("cmdline",   S_IRUGO, proc_pid_cmdline),
        ONE("stat",      S_IRUGO, proc_tid_stat),
@@ -3133,7 +3191,7 @@ static const struct pid_entry tid_base_stuff[] = {
 #ifdef CONFIG_PROC_PAGE_MONITOR
        REG("clear_refs", S_IWUSR, proc_clear_refs_operations),
        REG("smaps",     S_IRUGO, proc_smaps_operations),
-       REG("pagemap",    S_IRUSR, proc_pagemap_operations),
+       REG("pagemap",    S_IRUGO, proc_pagemap_operations),
 #endif
 #ifdef CONFIG_SECURITY
        DIR("attr",      S_IRUGO|S_IXUGO, proc_attr_dir_inode_operations, proc_attr_dir_operations),
@@ -3142,7 +3200,7 @@ static const struct pid_entry tid_base_stuff[] = {
        INF("wchan",     S_IRUGO, proc_pid_wchan),
 #endif
 #ifdef CONFIG_STACKTRACE
-       ONE("stack",      S_IRUSR, proc_pid_stack),
+       ONE("stack",      S_IRUGO, proc_pid_stack),
 #endif
 #ifdef CONFIG_SCHEDSTATS
        INF("schedstat", S_IRUGO, proc_pid_schedstat),
@@ -3161,7 +3219,7 @@ static const struct pid_entry tid_base_stuff[] = {
        REG("oom_score_adj", S_IRUGO|S_IWUSR, proc_oom_score_adj_operations),
 #ifdef CONFIG_AUDITSYSCALL
        REG("loginuid",  S_IWUSR|S_IRUGO, proc_loginuid_operations),
-       REG("sessionid",  S_IRUSR, proc_sessionid_operations),
+       REG("sessionid",  S_IRUGO, proc_sessionid_operations),
 #endif
 #ifdef CONFIG_FAULT_INJECTION
        REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),