[PATCH v4 09/15] LSM: drop bprm_secureexec hook

From: Kees Cook
Date: Mon Jul 31 2017 - 19:53:39 EST


This removes the bprm_secureexec hook since the logic has been folded into
the bprm_set_creds hook for all LSMs now.

Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: John Johansen <john.johansen@xxxxxxxxxxxxx>
Acked-by: James Morris <james.l.morris@xxxxxxxxxx>
Acked-by: Serge Hallyn <serge@xxxxxxxxxx>
---
fs/exec.c | 2 --
include/linux/lsm_hooks.h | 14 +++++---------
include/linux/security.h | 7 -------
security/security.c | 5 -----
4 files changed, 5 insertions(+), 23 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index 3762aef8b49e..f0e8d25eba9f 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1322,8 +1322,6 @@ EXPORT_SYMBOL(would_dump);

void setup_new_exec(struct linux_binprm * bprm)
{
- bprm->secureexec |= security_bprm_secureexec(bprm);
-
/*
* Once here, prepare_binrpm() will not be called any more, so
* the final state of setuid/setgid/fscaps can be merged into the
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 080f34e66017..2ddc1c7e8923 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -40,7 +40,11 @@
* interpreters. The hook can tell whether it has already been called by
* checking to see if @bprm->security is non-NULL. If so, then the hook
* may decide either to retain the security information saved earlier or
- * to replace it.
+ * to replace it. The hook must set @bprm->secureexec to 1 if a "secure
+ * exec" has happened as a result of this hook call. The flag is used to
+ * indicate the need for a sanitized execution environment, and is also
+ * passed in the ELF auxiliary table on the initial stack to indicate
+ * whether libc should enable secure mode.
* @bprm contains the linux_binprm structure.
* Return 0 if the hook is successful and permission is granted.
* @bprm_check_security:
@@ -68,12 +72,6 @@
* linux_binprm structure. This hook is a good place to perform state
* changes on the process such as clearing out non-inheritable signal
* state. This is called immediately after commit_creds().
- * @bprm_secureexec:
- * Return a boolean value (0 or 1) indicating whether a "secure exec"
- * is required. The flag is passed in the auxiliary table
- * on the initial stack to the ELF interpreter to indicate whether libc
- * should enable secure mode.
- * @bprm contains the linux_binprm structure.
*
* Security hooks for filesystem operations.
*
@@ -1368,7 +1366,6 @@ union security_list_options {

int (*bprm_set_creds)(struct linux_binprm *bprm);
int (*bprm_check_security)(struct linux_binprm *bprm);
- int (*bprm_secureexec)(struct linux_binprm *bprm);
void (*bprm_committing_creds)(struct linux_binprm *bprm);
void (*bprm_committed_creds)(struct linux_binprm *bprm);

@@ -1680,7 +1677,6 @@ struct security_hook_heads {
struct list_head vm_enough_memory;
struct list_head bprm_set_creds;
struct list_head bprm_check_security;
- struct list_head bprm_secureexec;
struct list_head bprm_committing_creds;
struct list_head bprm_committed_creds;
struct list_head sb_alloc_security;
diff --git a/include/linux/security.h b/include/linux/security.h
index af675b576645..133c41bb666d 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -80,7 +80,6 @@ extern int cap_capset(struct cred *new, const struct cred *old,
const kernel_cap_t *inheritable,
const kernel_cap_t *permitted);
extern int cap_bprm_set_creds(struct linux_binprm *bprm);
-extern int cap_bprm_secureexec(struct linux_binprm *bprm);
extern int cap_inode_setxattr(struct dentry *dentry, const char *name,
const void *value, size_t size, int flags);
extern int cap_inode_removexattr(struct dentry *dentry, const char *name);
@@ -223,7 +222,6 @@ int security_bprm_set_creds(struct linux_binprm *bprm);
int security_bprm_check(struct linux_binprm *bprm);
void security_bprm_committing_creds(struct linux_binprm *bprm);
void security_bprm_committed_creds(struct linux_binprm *bprm);
-int security_bprm_secureexec(struct linux_binprm *bprm);
int security_sb_alloc(struct super_block *sb);
void security_sb_free(struct super_block *sb);
int security_sb_copy_data(char *orig, char *copy);
@@ -515,11 +513,6 @@ static inline void security_bprm_committed_creds(struct linux_binprm *bprm)
{
}

-static inline int security_bprm_secureexec(struct linux_binprm *bprm)
-{
- return cap_bprm_secureexec(bprm);
-}
-
static inline int security_sb_alloc(struct super_block *sb)
{
return 0;
diff --git a/security/security.c b/security/security.c
index b9fea3999cf8..750b83186869 100644
--- a/security/security.c
+++ b/security/security.c
@@ -311,11 +311,6 @@ void security_bprm_committed_creds(struct linux_binprm *bprm)
call_void_hook(bprm_committed_creds, bprm);
}

-int security_bprm_secureexec(struct linux_binprm *bprm)
-{
- return call_int_hook(bprm_secureexec, 0, bprm);
-}
-
int security_sb_alloc(struct super_block *sb)
{
return call_int_hook(sb_alloc_security, 0, sb);
--
2.7.4