[PATCH] remove duplicated code from proc and ptrace

Extract common code used by ptrace_attach() and may_ptrace_attach()
into a separate function.

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Cc: <viro@parcelfarce.linux.theplanet.co.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 24eed13..84751f3 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -346,33 +346,6 @@ static int proc_root_link(struct inode *inode, struct dentry **dentry, struct vf
         (task->state == TASK_STOPPED || task->state == TASK_TRACED) && \
         security_ptrace(current,task) == 0))
 
-static int may_ptrace_attach(struct task_struct *task)
-{
-       int retval = 0;
-
-       task_lock(task);
-
-       if (!task->mm)
-               goto out;
-       if (((current->uid != task->euid) ||
-            (current->uid != task->suid) ||
-            (current->uid != task->uid) ||
-            (current->gid != task->egid) ||
-            (current->gid != task->sgid) ||
-            (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE))
-               goto out;
-       rmb();
-       if (task->mm->dumpable != 1 && !capable(CAP_SYS_PTRACE))
-               goto out;
-       if (security_ptrace(current, task))
-               goto out;
-
-       retval = 1;
-out:
-       task_unlock(task);
-       return retval;
-}
-
 static int proc_pid_environ(struct task_struct *task, char * buffer)
 {
        int res = 0;
@@ -382,7 +355,7 @@ static int proc_pid_environ(struct task_struct *task, char * buffer)
                if (len > PAGE_SIZE)
                        len = PAGE_SIZE;
                res = access_process_vm(task, mm->env_start, buffer, len, 0);
-               if (!may_ptrace_attach(task))
+               if (!ptrace_may_attach(task))
                        res = -ESRCH;
                mmput(mm);
        }
@@ -685,7 +658,7 @@ static ssize_t mem_read(struct file * file, char __user * buf,
        int ret = -ESRCH;
        struct mm_struct *mm;
 
-       if (!MAY_PTRACE(task) || !may_ptrace_attach(task))
+       if (!MAY_PTRACE(task) || !ptrace_may_attach(task))
                goto out;
 
        ret = -ENOMEM;
@@ -711,7 +684,7 @@ static ssize_t mem_read(struct file * file, char __user * buf,
 
                this_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
                retval = access_process_vm(task, src, page, this_len, 0);
-               if (!retval || !MAY_PTRACE(task) || !may_ptrace_attach(task)) {
+               if (!retval || !MAY_PTRACE(task) || !ptrace_may_attach(task)) {
                        if (!ret)
                                ret = -EIO;
                        break;
@@ -749,7 +722,7 @@ static ssize_t mem_write(struct file * file, const char * buf,
        struct task_struct *task = proc_task(file->f_dentry->d_inode);
        unsigned long dst = *ppos;
 
-       if (!MAY_PTRACE(task) || !may_ptrace_attach(task))
+       if (!MAY_PTRACE(task) || !ptrace_may_attach(task))
                return -ESRCH;
 
        page = (char *)__get_free_page(GFP_USER);

diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index 2afdafb..dc6f364 100644 (file)
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -90,6 +90,7 @@ extern void __ptrace_link(struct task_struct *child,
                          struct task_struct *new_parent);
 extern void __ptrace_unlink(struct task_struct *child);
 extern void ptrace_untrace(struct task_struct *child);
+extern int ptrace_may_attach(struct task_struct *task);
 
 static inline void ptrace_link(struct task_struct *child,
                               struct task_struct *new_parent)

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 8dcb8f6..019e04e 100644 (file)
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -118,6 +118,33 @@ int ptrace_check_attach(struct task_struct *child, int kill)
        return ret;
 }
 
+static int may_attach(struct task_struct *task)
+{
+       if (!task->mm)
+               return -EPERM;
+       if (((current->uid != task->euid) ||
+            (current->uid != task->suid) ||
+            (current->uid != task->uid) ||
+            (current->gid != task->egid) ||
+            (current->gid != task->sgid) ||
+            (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE))
+               return -EPERM;
+       smp_rmb();
+       if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE))
+               return -EPERM;
+
+       return security_ptrace(current, task);
+}
+
+int ptrace_may_attach(struct task_struct *task)
+{
+       int err;
+       task_lock(task);
+       err = may_attach(task);
+       task_unlock(task);
+       return !err;
+}
+
 int ptrace_attach(struct task_struct *task)
 {
        int retval;
@@ -127,22 +154,10 @@ int ptrace_attach(struct task_struct *task)
                goto bad;
        if (task == current)
                goto bad;
-       if (!task->mm)
-               goto bad;
-       if(((current->uid != task->euid) ||
-           (current->uid != task->suid) ||
-           (current->uid != task->uid) ||
-           (current->gid != task->egid) ||
-           (current->gid != task->sgid) ||
-           (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE))
-               goto bad;
-       smp_rmb();
-       if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE))
-               goto bad;
        /* the same process cannot be attached many times */
        if (task->ptrace & PT_PTRACED)
                goto bad;
-       retval = security_ptrace(current, task);
+       retval = may_attach(task);
        if (retval)
                goto bad;