| Message ID | 1525182503-13849-2-git-send-email-zohar@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
If you can add Andres Rodriguez <andresx7@gmail.com>, and Greg to your Cc list in the future patches that'd be appreciated. On Tue, May 01, 2018 at 09:48:18AM -0400, Mimi Zohar wrote: > Add an LSM hook prior to allowing firmware sysfs fallback loading. > > Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com> > Cc: Luis R. Rodriguez <mcgrof@suse.com> > Cc: David Howells <dhowells@redhat.com> > Cc: Kees Cook <keescook@chromium.org> > Cc: Matthew Garrett <mjg59@google.com> > --- > drivers/base/firmware_loader/fallback.c | 7 +++++++ > include/linux/fs.h | 1 + > 2 files changed, 8 insertions(+) > > diff --git a/drivers/base/firmware_loader/fallback.c b/drivers/base/firmware_loader/fallback.c > index 31b5015b59fe..23d2af30474e 100644 > --- a/drivers/base/firmware_loader/fallback.c > +++ b/drivers/base/firmware_loader/fallback.c > @@ -651,6 +651,8 @@ static bool fw_force_sysfs_fallback(unsigned int opt_flags) > > static bool fw_run_sysfs_fallback(unsigned int opt_flags) > { > + int ret; > + > if (fw_fallback_config.ignore_sysfs_fallback) { > pr_info_once("Ignoring firmware sysfs fallback due to sysctl knob\n"); > return false; > @@ -659,6 +661,11 @@ static bool fw_run_sysfs_fallback(unsigned int opt_flags) > if ((opt_flags & FW_OPT_NOFALLBACK)) > return false; > > + /* Also permit LSMs and IMA to fail firmware sysfs fallback */ > + ret = security_kernel_read_file(NULL, READING_FIRMWARE_FALLBACK); > + if (ret < 0) > + return ret; > + > return fw_force_sysfs_fallback(opt_flags); > } > > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 760d8da1b6c7..dc16a73c3d38 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -2810,6 +2810,7 @@ extern int do_pipe_flags(int *, int); > id(UNKNOWN, unknown) \ > id(FIRMWARE, firmware) \ > id(FIRMWARE_PREALLOC_BUFFER, firmware) \ > + id(FIRMWARE_FALLBACK, firmware) \ If you're going to add this perhaps FIRMWARE_FALLBACK_SYSFS as we may later get FIRMWARE_FALLBACK_EFI. Luis
On Fri, 2018-05-04 at 00:02 +0000, Luis R. Rodriguez wrote: > If you can add Andres Rodriguez <andresx7@gmail.com>, and Greg to your Cc list > in the future patches that'd be appreciated. > > On Tue, May 01, 2018 at 09:48:18AM -0400, Mimi Zohar wrote: > > Add an LSM hook prior to allowing firmware sysfs fallback loading. > > > > Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com> > > Cc: Luis R. Rodriguez <mcgrof@suse.com> > > Cc: David Howells <dhowells@redhat.com> > > Cc: Kees Cook <keescook@chromium.org> > > Cc: Matthew Garrett <mjg59@google.com> > > --- > > drivers/base/firmware_loader/fallback.c | 7 +++++++ > > include/linux/fs.h | 1 + > > 2 files changed, 8 insertions(+) > > > > diff --git a/drivers/base/firmware_loader/fallback.c b/drivers/base/firmware_loader/fallback.c > > index 31b5015b59fe..23d2af30474e 100644 > > --- a/drivers/base/firmware_loader/fallback.c > > +++ b/drivers/base/firmware_loader/fallback.c > > @@ -651,6 +651,8 @@ static bool fw_force_sysfs_fallback(unsigned int opt_flags) > > > > static bool fw_run_sysfs_fallback(unsigned int opt_flags) > > { > > + int ret; > > + > > if (fw_fallback_config.ignore_sysfs_fallback) { > > pr_info_once("Ignoring firmware sysfs fallback due to sysctl knob\n"); > > return false; > > @@ -659,6 +661,11 @@ static bool fw_run_sysfs_fallback(unsigned int opt_flags) > > if ((opt_flags & FW_OPT_NOFALLBACK)) > > return false; > > > > + /* Also permit LSMs and IMA to fail firmware sysfs fallback */ > > + ret = security_kernel_read_file(NULL, READING_FIRMWARE_FALLBACK); > > + if (ret < 0) > > + return ret; > > + > > return fw_force_sysfs_fallback(opt_flags); > > } > > > > diff --git a/include/linux/fs.h b/include/linux/fs.h > > index 760d8da1b6c7..dc16a73c3d38 100644 > > --- a/include/linux/fs.h > > +++ b/include/linux/fs.h > > @@ -2810,6 +2810,7 @@ extern int do_pipe_flags(int *, int); > > id(UNKNOWN, unknown) \ > > id(FIRMWARE, firmware) \ > > id(FIRMWARE_PREALLOC_BUFFER, firmware) \ > > + id(FIRMWARE_FALLBACK, firmware) \ > > If you're going to add this perhaps FIRMWARE_FALLBACK_SYSFS as we may later > get FIRMWARE_FALLBACK_EFI. From an IMA signature verification perspective, both are buffer based. The file signature is stored as a security xattr. Without a file descriptor, the kernel cannot verify the firmware signature. I don't have a problem with defining another enumeration. Perhaps other LSMs will want to be able to differentiate between sysfs and EFI fallback methods. Mimi
diff --git a/drivers/base/firmware_loader/fallback.c b/drivers/base/firmware_loader/fallback.c index 31b5015b59fe..23d2af30474e 100644 --- a/drivers/base/firmware_loader/fallback.c +++ b/drivers/base/firmware_loader/fallback.c @@ -651,6 +651,8 @@ static bool fw_force_sysfs_fallback(unsigned int opt_flags) static bool fw_run_sysfs_fallback(unsigned int opt_flags) { + int ret; + if (fw_fallback_config.ignore_sysfs_fallback) { pr_info_once("Ignoring firmware sysfs fallback due to sysctl knob\n"); return false; @@ -659,6 +661,11 @@ static bool fw_run_sysfs_fallback(unsigned int opt_flags) if ((opt_flags & FW_OPT_NOFALLBACK)) return false; + /* Also permit LSMs and IMA to fail firmware sysfs fallback */ + ret = security_kernel_read_file(NULL, READING_FIRMWARE_FALLBACK); + if (ret < 0) + return ret; + return fw_force_sysfs_fallback(opt_flags); } diff --git a/include/linux/fs.h b/include/linux/fs.h index 760d8da1b6c7..dc16a73c3d38 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2810,6 +2810,7 @@ extern int do_pipe_flags(int *, int); id(UNKNOWN, unknown) \ id(FIRMWARE, firmware) \ id(FIRMWARE_PREALLOC_BUFFER, firmware) \ + id(FIRMWARE_FALLBACK, firmware) \ id(MODULE, kernel-module) \ id(KEXEC_IMAGE, kexec-image) \ id(KEXEC_INITRAMFS, kexec-initramfs) \
Add an LSM hook prior to allowing firmware sysfs fallback loading. Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com> Cc: Luis R. Rodriguez <mcgrof@suse.com> Cc: David Howells <dhowells@redhat.com> Cc: Kees Cook <keescook@chromium.org> Cc: Matthew Garrett <mjg59@google.com> --- drivers/base/firmware_loader/fallback.c | 7 +++++++ include/linux/fs.h | 1 + 2 files changed, 8 insertions(+)