From 5096add84b9e96e2e0a9c72675c442fe5433388a Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Tue, 8 May 2007 00:26:04 -0700 Subject: proc: maps protection The /proc/pid/ "maps", "smaps", and "numa_maps" files contain sensitive information about the memory location and usage of processes. Issues: - maps should not be world-readable, especially if programs expect any kind of ASLR protection from local attackers. - maps cannot just be 0400 because "-D_FORTIFY_SOURCE=2 -O2" makes glibc check the maps when %n is in a *printf call, and a setuid(getuid()) process wouldn't be able to read its own maps file. (For reference see http://lkml.org/lkml/2006/1/22/150) - a system-wide toggle is needed to allow prior behavior in the case of non-root applications that depend on access to the maps contents. This change implements a check using "ptrace_may_attach" before allowing access to read the maps contents. To control this protection, the new knob /proc/sys/kernel/maps_protect has been added, with corresponding updates to the procfs documentation. [akpm@linux-foundation.org: build fixes] [akpm@linux-foundation.org: New sysctl numbers are old hat] Signed-off-by: Kees Cook Cc: Arjan van de Ven Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/task_mmu.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) (limited to 'fs/proc/task_mmu.c') diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 4008c060f7ef..c24d81a5a040 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -3,6 +3,7 @@ #include #include #include +#include #include #include @@ -142,6 +143,9 @@ static int show_map_internal(struct seq_file *m, void *v, struct mem_size_stats dev_t dev = 0; int len; + if (maps_protect && !ptrace_may_attach(task)) + return -EACCES; + if (file) { struct inode *inode = vma->vm_file->f_path.dentry->d_inode; dev = inode->i_sb->s_dev; @@ -512,11 +516,22 @@ const struct file_operations proc_maps_operations = { #ifdef CONFIG_NUMA extern int show_numa_map(struct seq_file *m, void *v); +static int show_numa_map_checked(struct seq_file *m, void *v) +{ + struct proc_maps_private *priv = m->private; + struct task_struct *task = priv->task; + + if (maps_protect && !ptrace_may_attach(task)) + return -EACCES; + + return show_numa_map(m, v); +} + static struct seq_operations proc_pid_numa_maps_op = { .start = m_start, .next = m_next, .stop = m_stop, - .show = show_numa_map + .show = show_numa_map_checked }; static int numa_maps_open(struct inode *inode, struct file *file) -- cgit v1.2.3