1 files changed, 126 insertions, 63 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index d49c4b5d2c3e..dfa532730e55 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -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.
+         */
+        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.
          */
-        return -EPERM;
+        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),
@@ -3066,11 +3124,16 @@ static int proc_pid_fill_cache(struct file *filp, void *dirent, filldir_t filldi
 /* for the /proc/ directory itself, after non-process stuff has been done */
 int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
 {
-        unsigned int nr = filp->f_pos - FIRST_PROCESS_ENTRY;
-        struct task_struct *reaper = get_proc_task(filp->f_path.dentry->d_inode);
+        unsigned int nr;
+        struct task_struct *reaper;
         struct tgid_iter iter;
         struct pid_namespace *ns;
 
+        if (filp->f_pos >= PID_MAX_LIMIT + TGID_OFFSET)
+                goto out_no_task;
+        nr = filp->f_pos - FIRST_PROCESS_ENTRY;
+
+        reaper = get_proc_task(filp->f_path.dentry->d_inode);
         if (!reaper)
                 goto out_no_task;
 
@@ -3108,14 +3171,14 @@ 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 +3196,7 @@ 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 +3205,7 @@ 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 +3224,7 @@ 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),