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Subject[patch 81/88] fs core fixes
2.6.28-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Hugh Dickins <hugh@veritas.com>

Please add the following 4 commits to 2.6.27-stable and 2.6.28-stable.
However, there has been a lot of change here between 2.6.28 and 2.6.29:
in particular, fs/exec.c's unsafe_exec() grew into the more complicated
check_unsafe_exec(). So applying the original patches gives too many
rejects: at the bottom is the diffstat and the combined patch required.

1
Commit: 53e9309e01277ec99c38e84e0ca16921287cf470
Author: Hugh Dickins <hugh@veritas.com>
Date: Sat, 28 Mar 2009 23:16:03 +0000 (+0000)
Subject: [patch 81/88] compat_do_execve should unshare_files

2
Commit: e426b64c412aaa3e9eb3e4b261dc5be0d5a83e78
Author: Hugh Dickins <hugh@veritas.com>
Date: Sat, 28 Mar 2009 23:20:19 +0000 (+0000)
Subject: [patch 81/88] fix setuid sometimes doesn't

3
Commit: 7c2c7d993044cddc5010f6f429b100c63bc7dffb
Author: Hugh Dickins <hugh@veritas.com>
Date: Sat, 28 Mar 2009 23:21:27 +0000 (+0000)
Subject: [patch 81/88] fix setuid sometimes wouldn't

4
Commit: f1191b50ec11c8e2ca766d6d99eb5bb9d2c084a3
Author: Al Viro <viro@zeniv.linux.org.uk>
Date: Mon, 30 Mar 2009 11:35:18 +0000 (-0400)
Subject: [patch 81/88] check_unsafe_exec() doesn't care about signal handlers sharing

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
fs/compat.c | 12 +++++++++++-
fs/exec.c | 4 +---
fs/proc/base.c | 50 ++++++++++++++++----------------------------------
3 files changed, 28 insertions(+), 38 deletions(-)

--- a/fs/compat.c
+++ b/fs/compat.c
@@ -1386,12 +1386,17 @@ int compat_do_execve(char * filename,
{
struct linux_binprm *bprm;
struct file *file;
+ struct files_struct *displaced;
int retval;

+ retval = unshare_files(&displaced);
+ if (retval)
+ goto out_ret;
+
retval = -ENOMEM;
bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
if (!bprm)
- goto out_ret;
+ goto out_files;

file = open_exec(filename);
retval = PTR_ERR(file);
@@ -1443,6 +1448,8 @@ int compat_do_execve(char * filename,
security_bprm_free(bprm);
acct_update_integrals(current);
free_bprm(bprm);
+ if (displaced)
+ put_files_struct(displaced);
return retval;
}

@@ -1463,6 +1470,9 @@ out_file:
out_kfree:
free_bprm(bprm);

+out_files:
+ if (displaced)
+ reset_files_struct(displaced);
out_ret:
return retval;
}
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1084,9 +1084,7 @@ static int unsafe_exec(struct task_struc
{
int unsafe = tracehook_unsafe_exec(p);

- if (atomic_read(&p->fs->count) > 1 ||
- atomic_read(&p->files->count) > 1 ||
- atomic_read(&p->sighand->count) > 1)
+ if (atomic_read(&p->fs->count) > 1)
unsafe |= LSM_UNSAFE_SHARE;

return unsafe;
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -148,15 +148,22 @@ static unsigned int pid_entry_count_dirs
return count;
}

-static struct fs_struct *get_fs_struct(struct task_struct *task)
+static int get_fs_path(struct task_struct *task, struct path *path, bool root)
{
struct fs_struct *fs;
+ int result = -ENOENT;
+
task_lock(task);
fs = task->fs;
- if(fs)
- atomic_inc(&fs->count);
+ if (fs) {
+ read_lock(&fs->lock);
+ *path = root ? fs->root : fs->pwd;
+ path_get(path);
+ read_unlock(&fs->lock);
+ result = 0;
+ }
task_unlock(task);
- return fs;
+ return result;
}

static int get_nr_threads(struct task_struct *tsk)
@@ -174,42 +181,24 @@ static int get_nr_threads(struct task_st
static int proc_cwd_link(struct inode *inode, struct path *path)
{
struct task_struct *task = get_proc_task(inode);
- struct fs_struct *fs = NULL;
int result = -ENOENT;

if (task) {
- fs = get_fs_struct(task);
+ result = get_fs_path(task, path, 0);
put_task_struct(task);
}
- if (fs) {
- read_lock(&fs->lock);
- *path = fs->pwd;
- path_get(&fs->pwd);
- read_unlock(&fs->lock);
- result = 0;
- put_fs_struct(fs);
- }
return result;
}

static int proc_root_link(struct inode *inode, struct path *path)
{
struct task_struct *task = get_proc_task(inode);
- struct fs_struct *fs = NULL;
int result = -ENOENT;

if (task) {
- fs = get_fs_struct(task);
+ result = get_fs_path(task, path, 1);
put_task_struct(task);
}
- if (fs) {
- read_lock(&fs->lock);
- *path = fs->root;
- path_get(&fs->root);
- read_unlock(&fs->lock);
- result = 0;
- put_fs_struct(fs);
- }
return result;
}

@@ -567,7 +556,6 @@ static int mounts_open_common(struct ino
struct task_struct *task = get_proc_task(inode);
struct nsproxy *nsp;
struct mnt_namespace *ns = NULL;
- struct fs_struct *fs = NULL;
struct path root;
struct proc_mounts *p;
int ret = -EINVAL;
@@ -581,22 +569,16 @@ static int mounts_open_common(struct ino
get_mnt_ns(ns);
}
rcu_read_unlock();
- if (ns)
- fs = get_fs_struct(task);
+ if (ns && get_fs_path(task, &root, 1) == 0)
+ ret = 0;
put_task_struct(task);
}

if (!ns)
goto err;
- if (!fs)
+ if (ret)
goto err_put_ns;

- read_lock(&fs->lock);
- root = fs->root;
- path_get(&root);
- read_unlock(&fs->lock);
- put_fs_struct(fs);
-
ret = -ENOMEM;
p = kmalloc(sizeof(struct proc_mounts), GFP_KERNEL);
if (!p)



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