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author | Kees Cook <kees@outflux.net> | 2007-05-08 00:26:04 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-05-08 11:15:02 -0700 |
commit | 5096add84b9e96e2e0a9c72675c442fe5433388a (patch) | |
tree | f0444013cb7db32596d2b6febafc1ee4c2a4ea1f /fs/proc | |
parent | 4a1ccb5b1eff949a90ab830869cb23d6609c3d5f (diff) | |
download | op-kernel-dev-5096add84b9e96e2e0a9c72675c442fe5433388a.zip op-kernel-dev-5096add84b9e96e2e0a9c72675c442fe5433388a.tar.gz |
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 <kees@outflux.net>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc')
-rw-r--r-- | fs/proc/base.c | 4 | ||||
-rw-r--r-- | fs/proc/internal.h | 2 | ||||
-rw-r--r-- | fs/proc/task_mmu.c | 17 | ||||
-rw-r--r-- | fs/proc/task_nommu.c | 7 |
4 files changed, 29 insertions, 1 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index a721acf..17f7a7e 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -64,6 +64,7 @@ #include <linux/smp_lock.h> #include <linux/rcupdate.h> #include <linux/kallsyms.h> +#include <linux/module.h> #include <linux/mount.h> #include <linux/security.h> #include <linux/ptrace.h> @@ -123,6 +124,9 @@ struct pid_entry { NULL, &proc_info_file_operations, \ { .proc_read = &proc_##OTYPE } ) +int maps_protect; +EXPORT_SYMBOL(maps_protect); + static struct fs_struct *get_fs_struct(struct task_struct *task) { struct fs_struct *fs; diff --git a/fs/proc/internal.h b/fs/proc/internal.h index f771889..b215c35 100644 --- a/fs/proc/internal.h +++ b/fs/proc/internal.h @@ -37,6 +37,8 @@ do { \ extern int nommu_vma_show(struct seq_file *, struct vm_area_struct *); #endif +extern int maps_protect; + extern void create_seq_entry(char *name, mode_t mode, const struct file_operations *f); extern int proc_exe_link(struct inode *, struct dentry **, struct vfsmount **); extern int proc_tid_stat(struct task_struct *, char *); diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 4008c06..c24d81a 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -3,6 +3,7 @@ #include <linux/mount.h> #include <linux/seq_file.h> #include <linux/highmem.h> +#include <linux/ptrace.h> #include <linux/pagemap.h> #include <linux/mempolicy.h> @@ -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) diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c index 7cddf6b..d8b8c71 100644 --- a/fs/proc/task_nommu.c +++ b/fs/proc/task_nommu.c @@ -2,6 +2,7 @@ #include <linux/mm.h> #include <linux/file.h> #include <linux/mount.h> +#include <linux/ptrace.h> #include <linux/seq_file.h> #include "internal.h" @@ -143,6 +144,12 @@ out: static int show_map(struct seq_file *m, void *_vml) { struct vm_list_struct *vml = _vml; + struct proc_maps_private *priv = m->private; + struct task_struct *task = priv->task; + + if (maps_protect && !ptrace_may_attach(task)) + return -EACCES; + return nommu_vma_show(m, vml->vma); } |