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LoadPin: Ignore the "contents" argument of the LSM hooks 

[ Upstream commit 1a17e5b513 ]

LoadPin only enforces the read-only origin of kernel file reads. Whether
or not it was a partial read isn't important. Remove the overly
conservative checks so that things like partial firmware reads will
succeed (i.e. reading a firmware header).

Fixes: 2039bda1fa ("LSM: Add "contents" flag to kernel_read_file hook")
Cc: Paul Moore <paul@paul-moore.com>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: linux-security-module@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Serge Hallyn <serge@hallyn.com>
Tested-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://lore.kernel.org/r/20221209195453.never.494-kees@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Kees Cook 2022-12-09 11:54:57 -08:00 committed by Greg Kroah-Hartman
parent 2d57269cab
commit 2c5e64f0a8
1 changed files with 18 additions and 12 deletions
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30
security/loadpin/loadpin.c
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@ -122,21 +122,11 @@ static void loadpin_sb_free_security(struct super_block *mnt_sb)
}
}
static int loadpin_read_file(struct file *file, enum kernel_read_file_id id,
bool contents)
static int loadpin_check(struct file *file, enum kernel_read_file_id id)
{
struct super_block *load_root;
const char *origin = kernel_read_file_id_str(id);
/*
* If we will not know that we'll be seeing the full contents
* then we cannot trust a load will be complete and unchanged
* off disk. Treat all contents=false hooks as if there were
* no associated file struct.
*/
if (!contents)
file = NULL;
/* If the file id is excluded, ignore the pinning. */
if ((unsigned int)id < ARRAY_SIZE(ignore_read_file_id) &&
ignore_read_file_id[id]) {
@ -192,9 +182,25 @@ static int loadpin_read_file(struct file *file, enum kernel_read_file_id id,
return 0;
}
static int loadpin_read_file(struct file *file, enum kernel_read_file_id id,
bool contents)
{
/*
* LoadPin only cares about the _origin_ of a file, not its
* contents, so we can ignore the "are full contents available"
* argument here.
*/
return loadpin_check(file, id);
}
static int loadpin_load_data(enum kernel_load_data_id id, bool contents)
{
return loadpin_read_file(NULL, (enum kernel_read_file_id) id, contents);
/*
* LoadPin only cares about the _origin_ of a file, not its
* contents, so a NULL file is passed, and we can ignore the
* state of "contents".
*/
return loadpin_check(NULL, (enum kernel_read_file_id) id);
}
static struct security_hook_list loadpin_hooks[] __lsm_ro_after_init = {