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module: replace copy_module_from_fd with kernel version

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Replace copy_module_from_fd() with kernel_read_file_from_fd().

Although none of the upstreamed LSMs define a kernel_module_from_file
hook, IMA is called, based on policy, to prevent unsigned kernel modules
from being loaded by the original kernel module syscall and to
measure/appraise signed kernel modules.

The security function security_kernel_module_from_file() was called prior
to reading a kernel module.  Preventing unsigned kernel modules from being
loaded by the original kernel module syscall remains on the pre-read
kernel_read_file() security hook.  Instead of reading the kernel module
twice, once for measuring/appraising and again for loading the kernel
module, the signature validation is moved to the kernel_post_read_file()
security hook.

This patch removes the security_kernel_module_from_file() hook and security
call.

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Luis R. Rodriguez <mcgrof@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Mimi Zohar
2015-12-30 07:35:30 -05:00
parent b844f0ecbc
commit a1db742094
7 changed files with 22 additions and 112 deletions
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68
kernel/module.c
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@@ -2654,7 +2654,7 @@ static int copy_module_from_user(const void __user *umod, unsigned long len,
if (info->len < sizeof(*(info->hdr)))
return -ENOEXEC;
err = security_kernel_module_from_file(NULL);
err = security_kernel_read_file(NULL, READING_MODULE);
if (err)
return err;
@@ -2672,63 +2672,6 @@ static int copy_module_from_user(const void __user *umod, unsigned long len,
return 0;
}
/* Sets info->hdr and info->len. */
static int copy_module_from_fd(int fd, struct load_info *info)
{
struct fd f = fdget(fd);
int err;
struct kstat stat;
loff_t pos;
ssize_t bytes = 0;
if (!f.file)
return -ENOEXEC;
err = security_kernel_module_from_file(f.file);
if (err)
goto out;
err = vfs_getattr(&f.file->f_path, &stat);
if (err)
goto out;
if (stat.size > INT_MAX) {
err = -EFBIG;
goto out;
}
/* Don't hand 0 to vmalloc, it whines. */
if (stat.size == 0) {
err = -EINVAL;
goto out;
}
info->hdr = vmalloc(stat.size);
if (!info->hdr) {
err = -ENOMEM;
goto out;
}
pos = 0;
while (pos < stat.size) {
bytes = kernel_read(f.file, pos, (char *)(info->hdr) + pos,
stat.size - pos);
if (bytes < 0) {
vfree(info->hdr);
err = bytes;
goto out;
}
if (bytes == 0)
break;
pos += bytes;
}
info->len = pos;
out:
fdput(f);
return err;
}
static void free_copy(struct load_info *info)
{
vfree(info->hdr);
@@ -3589,8 +3532,10 @@ SYSCALL_DEFINE3(init_module, void __user *, umod,
SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags)
{
int err;
struct load_info info = { };
loff_t size;
void *hdr;
int err;
err = may_init_module();
if (err)
@@ -3602,9 +3547,12 @@ SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags)
|MODULE_INIT_IGNORE_VERMAGIC))
return -EINVAL;
err = copy_module_from_fd(fd, &info);
err = kernel_read_file_from_fd(fd, &hdr, &size, INT_MAX,
READING_MODULE);
if (err)
return err;
info.hdr = hdr;
info.len = size;
return load_module(&info, uargs, flags);
}