diff options
| author | Al Viro <viro@ZenIV.linux.org.uk> | 2008-01-02 14:09:57 +0000 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2008-01-02 13:13:27 -0800 |
| commit | 831830b5a2b5d413407adf380ef62fe17d6fcbf2 (patch) | |
| tree | b08f54f15374b5b98b0b3bea20a1d2ea8d1f50e0 /fs | |
| parent | ac40532ef0b8649e6f7f83859ea0de1c4ed08a19 (diff) | |
restrict reading from /proc/<pid>/maps to those who share ->mm or can ptrace pid
Contents of /proc/*/maps is sensitive and may become sensitive after
open() (e.g. if target originally shares our ->mm and later does exec
on suid-root binary).
Check at read() (actually, ->start() of iterator) time that mm_struct
we'd grabbed and locked is
- still the ->mm of target
- equal to reader's ->mm or the target is ptracable by reader.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/proc/base.c | 20 | ||||
| -rw-r--r-- | fs/proc/internal.h | 2 | ||||
| -rw-r--r-- | fs/proc/task_mmu.c | 3 | ||||
| -rw-r--r-- | fs/proc/task_nommu.c | 4 |
4 files changed, 24 insertions, 5 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index 02a63ac0417..7411bfb0b7c 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -202,6 +202,26 @@ 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)) +struct mm_struct *mm_for_maps(struct task_struct *task) +{ + struct mm_struct *mm = get_task_mm(task); + if (!mm) + return NULL; + down_read(&mm->mmap_sem); + task_lock(task); + if (task->mm != mm) + goto out; + if (task->mm != current->mm && __ptrace_may_attach(task) < 0) + goto out; + task_unlock(task); + return mm; +out: + task_unlock(task); + up_read(&mm->mmap_sem); + mmput(mm); + return NULL; +} + static int proc_pid_cmdline(struct task_struct *task, char * buffer) { int res = 0; diff --git a/fs/proc/internal.h b/fs/proc/internal.h index 1820eb2ef76..05b3e900626 100644 --- a/fs/proc/internal.h +++ b/fs/proc/internal.h @@ -27,6 +27,8 @@ struct vmalloc_info { unsigned long largest_chunk; }; +extern struct mm_struct *mm_for_maps(struct task_struct *); + #ifdef CONFIG_MMU #define VMALLOC_TOTAL (VMALLOC_END - VMALLOC_START) extern void get_vmalloc_info(struct vmalloc_info *vmi); diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index c24d81a5a04..8043a3eab52 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -397,12 +397,11 @@ static void *m_start(struct seq_file *m, loff_t *pos) if (!priv->task) return NULL; - mm = get_task_mm(priv->task); + mm = mm_for_maps(priv->task); if (!mm) return NULL; priv->tail_vma = tail_vma = get_gate_vma(priv->task); - down_read(&mm->mmap_sem); /* Start with last addr hint */ if (last_addr && (vma = find_vma(mm, last_addr))) { diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c index d8b8c7183c2..1932c2ca345 100644 --- a/fs/proc/task_nommu.c +++ b/fs/proc/task_nommu.c @@ -165,15 +165,13 @@ static void *m_start(struct seq_file *m, loff_t *pos) if (!priv->task) return NULL; - mm = get_task_mm(priv->task); + mm = mm_for_maps(priv->task); if (!mm) { put_task_struct(priv->task); priv->task = NULL; return NULL; } - down_read(&mm->mmap_sem); - /* start from the Nth VMA */ for (vml = mm->context.vmlist; vml; vml = vml->next) if (n-- == 0) |