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Message-ID: <20090603230422.GB853@x200.localdomain>
Date: Thu, 4 Jun 2009 03:04:22 +0400
From: Alexey Dobriyan <adobriyan@...il.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Matt Helsley <matthltc@...ibm.com>, xemul@...allels.com,
containers@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org, dave@...ux.vnet.ibm.com,
mingo@...e.hu, torvalds@...ux-foundation.org,
linux-fsdevel@...r.kernel.org
Subject: [PATCH 1/9] exec_path 1/9: introduce ->exec_path and switch
/proc/*/exe
On Sun, May 31, 2009 at 03:19:53PM -0700, Andrew Morton wrote:
> On Mon, 1 Jun 2009 01:54:27 +0400 Alexey Dobriyan <adobriyan@...il.com> wrote:
>
> > And BTW, there is something unnatural when executable path is attached
> > to mm_struct(!) not task_struct,
>
> mm_struct is the central object for a heavyweight process. All threads
> within that process share the same executable path (don't they?) so
> attaching the executable path to the mm seems OK to me.
OK, let's try this:
[PATCH 1/9] exec_path 1/9: introduce ->exec_path and switch /proc/*/exe
->exec_path marks executable which is associated with running task.
Binfmt loader decides which executable is such and can, in theory,
assign anything. Unlike current status quo when first VM_EXECUTABLE mapping is
sort of marks running executable.
If executable unmaps its all VM_EXECUTABLE mappings, /proc/*/exe ceases
to exists, ick! And userpsace can't even use MAP_EXECUTABLE.
Tasks which aren't created by running clone(2) and execve(2)
(read: kernel threads) get empty ->exec_path and
->exec_path is copied on clone(2) and put at do_exit() time.
->exec_path is going to replace struct mm_struct::exe_file et al
and allows to remove VM_EXECUTABLE flag while keeping readlink("/proc/*/exe")
without loop over all VMAs.
Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---
fs/binfmt_aout.c | 1 +
fs/binfmt_elf.c | 1 +
fs/binfmt_elf_fdpic.c | 1 +
fs/binfmt_flat.c | 1 +
fs/binfmt_som.c | 1 +
fs/proc/base.c | 38 ++++++++++++++------------------------
include/linux/sched.h | 25 +++++++++++++++++++++++++
kernel/exit.c | 1 +
kernel/fork.c | 2 ++
9 files changed, 47 insertions(+), 24 deletions(-)
diff --git a/fs/binfmt_aout.c b/fs/binfmt_aout.c
index b639dcf..a19b185 100644
--- a/fs/binfmt_aout.c
+++ b/fs/binfmt_aout.c
@@ -379,6 +379,7 @@ beyond_if:
regs->gp = ex.a_gpvalue;
#endif
start_thread(regs, ex.a_entry, current->mm->start_stack);
+ set_task_exec_path(current, &bprm->file->f_path);
return 0;
}
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 40381df..b815bfc 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -999,6 +999,7 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
#endif
start_thread(regs, elf_entry, bprm->p);
+ set_task_exec_path(current, &bprm->file->f_path);
retval = 0;
out:
kfree(loc);
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index fdb66fa..f545504 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -1185,6 +1185,7 @@ static int elf_fdpic_map_file_by_direct_mmap(struct elf_fdpic_params *params,
seg++;
}
+ set_task_exec_path(current, &file->f_path);
return 0;
}
diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 697f6b5..a16f977 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -798,6 +798,7 @@ static int load_flat_file(struct linux_binprm * bprm,
libinfo->lib_list[id].start_brk) + /* start brk */
stack_len);
+ set_task_exec_path(current, &bprm->file->f_path);
return 0;
err:
return ret;
diff --git a/fs/binfmt_som.c b/fs/binfmt_som.c
index eff74b9..6c56262 100644
--- a/fs/binfmt_som.c
+++ b/fs/binfmt_som.c
@@ -174,6 +174,7 @@ static int map_som_binary(struct file *file,
up_write(¤t->mm->mmap_sem);
if (retval > 0 || retval < -1024)
retval = 0;
+ set_task_exec_path(current, &bprm->file->f_path);
out:
set_fs(old_fs);
return retval;
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 3326bbf..dc4ee6a 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -201,6 +201,20 @@ static int proc_root_link(struct inode *inode, struct path *path)
return result;
}
+static int proc_exe_link(struct inode *inode, struct path *path)
+{
+ struct task_struct *tsk;
+
+ tsk = get_proc_task(inode);
+ if (!tsk)
+ return -ENOENT;
+ get_task_exec_path(tsk, path);
+ put_task_struct(tsk);
+ if (!path->mnt || !path->dentry)
+ return -ENOENT;
+ return 0;
+}
+
/*
* Return zero if current may access user memory in @task, -error if not.
*/
@@ -1302,30 +1316,6 @@ void dup_mm_exe_file(struct mm_struct *oldmm, struct mm_struct *newmm)
newmm->exe_file = get_mm_exe_file(oldmm);
}
-static int proc_exe_link(struct inode *inode, struct path *exe_path)
-{
- struct task_struct *task;
- struct mm_struct *mm;
- struct file *exe_file;
-
- task = get_proc_task(inode);
- if (!task)
- return -ENOENT;
- mm = get_task_mm(task);
- put_task_struct(task);
- if (!mm)
- return -ENOENT;
- exe_file = get_mm_exe_file(mm);
- mmput(mm);
- if (exe_file) {
- *exe_path = exe_file->f_path;
- path_get(&exe_file->f_path);
- fput(exe_file);
- return 0;
- } else
- return -ENOENT;
-}
-
static void *proc_pid_follow_link(struct dentry *dentry, struct nameidata *nd)
{
struct inode *inode = dentry->d_inode;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index b4c38bc..6b2dd01 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1265,6 +1265,12 @@ struct task_struct {
#endif
/* CPU-specific state of this task */
struct thread_struct thread;
+ /*
+ * Executable, binfmt loader wants to associate with task
+ * (read: execve(2) argument).
+ * Empty, if concept isn't applicable, e. g. kernel thread.
+ */
+ struct path exec_path;
/* filesystem information */
struct fs_struct *fs;
/* open file information */
@@ -2403,6 +2409,25 @@ static inline void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
#define TASK_STATE_TO_CHAR_STR "RSDTtZX"
+static inline void get_task_exec_path(struct task_struct *tsk, struct path *path)
+{
+ task_lock(tsk);
+ path_get(&tsk->exec_path);
+ *path = tsk->exec_path;
+ task_unlock(tsk);
+}
+
+static inline void set_task_exec_path(struct task_struct *tsk, struct path *path)
+{
+ struct path old_path;
+
+ path_get(path);
+ task_lock(tsk);
+ old_path = tsk->exec_path;
+ tsk->exec_path = *path;
+ task_unlock(tsk);
+ path_put(&old_path);
+}
#endif /* __KERNEL__ */
#endif
diff --git a/kernel/exit.c b/kernel/exit.c
index abf9cf3..8e70b54 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -962,6 +962,7 @@ NORET_TYPE void do_exit(long code)
exit_sem(tsk);
exit_files(tsk);
+ set_task_exec_path(tsk, &(struct path){ .mnt = NULL, .dentry = NULL });
exit_fs(tsk);
check_stack_usage();
exit_thread();
diff --git a/kernel/fork.c b/kernel/fork.c
index b9e2edd..c0ee931 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1191,6 +1191,8 @@ static struct task_struct *copy_process(unsigned long clone_flags,
cgroup_fork_callbacks(p);
cgroup_callbacks_done = 1;
+ get_task_exec_path(current, &p->exec_path);
+
/* Need tasklist lock for parent etc handling! */
write_lock_irq(&tasklist_lock);
--
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