* [PATCH 1/2] x86_64: Add safe check in a.out loaders and some coding style
@ 2013-09-18 2:54 Geyslan G. Bem
2013-09-18 2:54 ` [PATCH 2/2] x86: Useless inode var and Coding style fixes Geyslan G. Bem
0 siblings, 1 reply; 3+ messages in thread
From: Geyslan G. Bem @ 2013-09-18 2:54 UTC (permalink / raw)
To: viro, linux-fsdevel; +Cc: linux-kernel, Geyslan G. Bem
ia32_aout had no safe checks concerning the mmap and f_op in this module.
It's not necessary to verify f_op in the load_aout_library, since the
prior kernel_read/vfs_read function already does.
Coding style and printk strings fixes.
Tested using qemu, a handcrafted a.out binary and a a.out linked with a
cross-compiled ld.
Signed-off-by: Geyslan G. Bem <geyslan@gmail.com>
---
arch/x86/ia32/ia32_aout.c | 26 +++++++++++++++++++-------
1 file changed, 19 insertions(+), 7 deletions(-)
diff --git a/arch/x86/ia32/ia32_aout.c b/arch/x86/ia32/ia32_aout.c
index bae3aba..15a8319 100644
--- a/arch/x86/ia32/ia32_aout.c
+++ b/arch/x86/ia32/ia32_aout.c
@@ -271,10 +271,17 @@ static int load_aout_binary(struct linux_binprm *bprm)
N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
N_TRSIZE(ex) || N_DRSIZE(ex) ||
i_size_read(file_inode(bprm->file)) <
- ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
+ ex.a_text + ex.a_data + N_SYMSIZE(ex) + N_TXTOFF(ex)) {
return -ENOEXEC;
}
+ /*
+ * Requires a mmap handler. This prevents people from using a.out
+ * as part of an exploit attack against /proc-related vulnerabilities.
+ */
+ if (!bprm->file->f_op || !bprm->file->f_op->mmap)
+ return -ENOEXEC;
+
fd_offset = N_TXTOFF(ex);
/* Check initial limits. This avoids letting people circumvent
@@ -350,14 +357,13 @@ static int load_aout_binary(struct linux_binprm *bprm)
if ((fd_offset & ~PAGE_MASK) != 0 &&
time_after(jiffies, error_time + 5*HZ)) {
printk(KERN_WARNING
- "fd_offset is not page aligned. Please convert "
- "program: %s\n",
+ "fd_offset is not page aligned. Please convert program: %s\n",
bprm->file->f_path.dentry->d_name.name);
error_time = jiffies;
}
#endif
- if (!bprm->file->f_op->mmap || (fd_offset & ~PAGE_MASK) != 0) {
+ if ((fd_offset & ~PAGE_MASK) != 0) {
vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
read_code(bprm->file, N_TXTADDR(ex), fd_offset,
ex.a_text+ex.a_data);
@@ -424,10 +430,17 @@ static int load_aout_library(struct file *file)
if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
i_size_read(file_inode(file)) <
- ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
+ ex.a_text + ex.a_data + N_SYMSIZE(ex) + N_TXTOFF(ex)) {
goto out;
}
+ /*
+ * Requires a mmap handler. This prevents people from using a.out
+ * as part of an exploit attack against /proc-related vulnerabilities.
+ */
+ if (!file->f_op->mmap)
+ goto out;
+
if (N_FLAGS(ex))
goto out;
@@ -441,8 +454,7 @@ static int load_aout_library(struct file *file)
static unsigned long error_time;
if (time_after(jiffies, error_time + 5*HZ)) {
printk(KERN_WARNING
- "N_TXTOFF is not page aligned. Please convert "
- "library: %s\n",
+ "N_TXTOFF is not page aligned. Please convert library: %s\n",
file->f_path.dentry->d_name.name);
error_time = jiffies;
}
--
1.8.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH 2/2] x86: Useless inode var and Coding style fixes
2013-09-18 2:54 [PATCH 1/2] x86_64: Add safe check in a.out loaders and some coding style Geyslan G. Bem
@ 2013-09-18 2:54 ` Geyslan G. Bem
2013-09-18 5:25 ` Joe Perches
0 siblings, 1 reply; 3+ messages in thread
From: Geyslan G. Bem @ 2013-09-18 2:54 UTC (permalink / raw)
To: viro, linux-fsdevel; +Cc: linux-kernel, Geyslan G. Bem
file size read only one time: useless prior value allocation.
It's not necessary to verify f_op in the load_aout_library, since the
prior kernel_read/vfs_read function already does.
Coding style and printk strings fixes.
Tested using qemu, a handcrafted a.out binary and a a.out linked with a
cross-compiled ld.
Signed-off-by: Geyslan G. Bem <geyslan@gmail.com>
---
fs/binfmt_aout.c | 22 +++++++++++-----------
1 file changed, 11 insertions(+), 11 deletions(-)
diff --git a/fs/binfmt_aout.c b/fs/binfmt_aout.c
index 89dec7f..a4af504 100644
--- a/fs/binfmt_aout.c
+++ b/fs/binfmt_aout.c
@@ -142,7 +142,8 @@ static int set_brk(unsigned long start, unsigned long end)
* memory and creates the pointer tables from them, and puts their
* addresses on the "stack", returning the new stack pointer value.
*/
-static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
+static unsigned long __user *create_aout_tables(char __user *p,
+ struct linux_binprm *bprm)
{
char __user * __user *argv;
char __user * __user *envp;
@@ -213,7 +214,8 @@ static int load_aout_binary(struct linux_binprm * bprm)
if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
N_TRSIZE(ex) || N_DRSIZE(ex) ||
- i_size_read(file_inode(bprm->file)) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
+ i_size_read(file_inode(bprm->file)) <
+ ex.a_text + ex.a_data + N_SYMSIZE(ex) + N_TXTOFF(ex)) {
return -ENOEXEC;
}
@@ -299,12 +301,12 @@ static int load_aout_binary(struct linux_binprm * bprm)
if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
{
- printk(KERN_WARNING
+ printk(KERN_WARNING
"fd_offset is not page aligned. Please convert program: %s\n",
bprm->file->f_path.dentry->d_name.name);
}
- if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
+ if ((fd_offset & ~PAGE_MASK) != 0) {
vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
read_code(bprm->file, N_TXTADDR(ex), fd_offset,
ex.a_text + ex.a_data);
@@ -350,14 +352,11 @@ beyond_if:
static int load_aout_library(struct file *file)
{
- struct inode * inode;
unsigned long bss, start_addr, len;
unsigned long error;
int retval;
struct exec ex;
- inode = file_inode(file);
-
retval = -ENOEXEC;
error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
if (error != sizeof(ex))
@@ -366,7 +365,8 @@ static int load_aout_library(struct file *file)
/* We come in here for the regular a.out style of shared libraries */
if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
- i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
+ i_size_read(file_inode(file)) <
+ ex.a_text + ex.a_data + N_SYMSIZE(ex) + N_TXTOFF(ex)) {
goto out;
}
@@ -374,7 +374,7 @@ static int load_aout_library(struct file *file)
* Requires a mmap handler. This prevents people from using a.out
* as part of an exploit attack against /proc-related vulnerabilities.
*/
- if (!file->f_op || !file->f_op->mmap)
+ if (!file->f_op->mmap)
goto out;
if (N_FLAGS(ex))
@@ -388,12 +388,12 @@ static int load_aout_library(struct file *file)
if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
if (printk_ratelimit())
{
- printk(KERN_WARNING
+ printk(KERN_WARNING
"N_TXTOFF is not page aligned. Please convert library: %s\n",
file->f_path.dentry->d_name.name);
}
vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
-
+
read_code(file, start_addr, N_TXTOFF(ex),
ex.a_text + ex.a_data);
retval = 0;
--
1.8.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH 2/2] x86: Useless inode var and Coding style fixes
2013-09-18 2:54 ` [PATCH 2/2] x86: Useless inode var and Coding style fixes Geyslan G. Bem
@ 2013-09-18 5:25 ` Joe Perches
0 siblings, 0 replies; 3+ messages in thread
From: Joe Perches @ 2013-09-18 5:25 UTC (permalink / raw)
To: Geyslan G. Bem; +Cc: viro, linux-fsdevel, linux-kernel
On Tue, 2013-09-17 at 23:54 -0300, Geyslan G. Bem wrote:
> Coding style and printk strings fixes.
[]
> diff --git a/fs/binfmt_aout.c b/fs/binfmt_aout.c
[]
> @@ -299,12 +301,12 @@ static int load_aout_binary(struct linux_binprm * bprm)
>
> if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
> {
> - printk(KERN_WARNING
> + printk(KERN_WARNING
> "fd_offset is not page aligned. Please convert program: %s\n",
> bprm->file->f_path.dentry->d_name.name);
[]
> @@ -388,12 +388,12 @@ static int load_aout_library(struct file *file)
> if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
> if (printk_ratelimit())
> {
> - printk(KERN_WARNING
> + printk(KERN_WARNING
> "N_TXTOFF is not page aligned. Please convert library: %s\n",
> file->f_path.dentry->d_name.name);
I'd rather see these printks were fixed like this:
---
fs/binfmt_aout.c | 24 ++++++++----------------
1 file changed, 8 insertions(+), 16 deletions(-)
diff --git a/fs/binfmt_aout.c b/fs/binfmt_aout.c
index 89dec7f..3c9ec06 100644
--- a/fs/binfmt_aout.c
+++ b/fs/binfmt_aout.c
@@ -25,6 +25,7 @@
#include <linux/init.h>
#include <linux/coredump.h>
#include <linux/slab.h>
+#include <linux/ratelimit.h>
#include <asm/uaccess.h>
#include <asm/cacheflush.h>
@@ -292,17 +293,12 @@ static int load_aout_binary(struct linux_binprm * bprm)
}
} else {
if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
- (N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
- {
- printk(KERN_NOTICE "executable not page aligned\n");
- }
+ (N_MAGIC(ex) != NMAGIC))
+ pr_notice_ratelimited("executable not page aligned\n");
- if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
- {
- printk(KERN_WARNING
- "fd_offset is not page aligned. Please convert program: %s\n",
- bprm->file->f_path.dentry->d_name.name);
- }
+ if ((fd_offset & ~PAGE_MASK) != 0)
+ pr_warn_ratelimited("fd_offset is not page aligned. Please convert program: %s\n",
+ bprm->file->f_path.dentry->d_name.name);
if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
@@ -386,12 +382,8 @@ static int load_aout_library(struct file *file)
start_addr = ex.a_entry & 0xfffff000;
if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
- if (printk_ratelimit())
- {
- printk(KERN_WARNING
- "N_TXTOFF is not page aligned. Please convert library: %s\n",
- file->f_path.dentry->d_name.name);
- }
+ pr_warn_ratelimited("N_TXTOFF is not page aligned. Please convert library: %s\n",
+ file->f_path.dentry->d_name.name);
vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
read_code(file, start_addr, N_TXTOFF(ex),
^ permalink raw reply related [flat|nested] 3+ messages in thread
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2013-09-18 2:54 ` [PATCH 2/2] x86: Useless inode var and Coding style fixes Geyslan G. Bem
2013-09-18 5:25 ` Joe Perches
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