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Message-Id: <1322694098-21872-2-git-send-email-keescook@chromium.org> Date: Wed, 30 Nov 2011 15:01:37 -0800 From: Kees Cook <keescook@...omium.org> To: linux-kernel@...r.kernel.org Cc: linux-security-module@...r.kernel.org, Roland McGrath <roland@...k.frob.com>, James Morris <jmorris@...ei.org>, kernel-hardening@...ts.openwall.com Subject: [PATCH 1/2] security: create task_free security callback The current LSM interface to cred_free is not sufficient for allowing an LSM to track the life and death of a task. This patch adds the task_free hook so that an LSM can clean up resources on task death. Signed-off-by: Kees Cook <keescook@...omium.org> --- include/linux/security.h | 9 +++++++++ kernel/fork.c | 1 + security/capability.c | 4 ++++ security/security.c | 5 +++++ 4 files changed, 19 insertions(+), 0 deletions(-) diff --git a/include/linux/security.h b/include/linux/security.h index 19d8e04..256befc 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -650,6 +650,10 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts) * manual page for definitions of the @clone_flags. * @clone_flags contains the flags indicating what should be shared. * Return 0 if permission is granted. + * @task_free: + * @task task being freed + * Handle release of task-related resources. (Note that this can be called + * from interrupt context.) * @cred_alloc_blank: * @cred points to the credentials. * @gfp indicates the atomicity of any memory allocations. @@ -1500,6 +1504,7 @@ struct security_operations { int (*dentry_open) (struct file *file, const struct cred *cred); int (*task_create) (unsigned long clone_flags); + void (*task_free) (struct task_struct *task); int (*cred_alloc_blank) (struct cred *cred, gfp_t gfp); void (*cred_free) (struct cred *cred); int (*cred_prepare)(struct cred *new, const struct cred *old, @@ -1762,6 +1767,7 @@ int security_file_send_sigiotask(struct task_struct *tsk, int security_file_receive(struct file *file); int security_dentry_open(struct file *file, const struct cred *cred); int security_task_create(unsigned long clone_flags); +void security_task_free(struct task_struct *task); int security_cred_alloc_blank(struct cred *cred, gfp_t gfp); void security_cred_free(struct cred *cred); int security_prepare_creds(struct cred *new, const struct cred *old, gfp_t gfp); @@ -2273,6 +2279,9 @@ static inline int security_task_create(unsigned long clone_flags) return 0; } +static inline void security_task_free(struct task_struct *task) +{ } + static inline int security_cred_alloc_blank(struct cred *cred, gfp_t gfp) { return 0; diff --git a/kernel/fork.c b/kernel/fork.c index da4a6a1..d707601 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -189,6 +189,7 @@ void __put_task_struct(struct task_struct *tsk) WARN_ON(atomic_read(&tsk->usage)); WARN_ON(tsk == current); + security_task_free(tsk); exit_creds(tsk); delayacct_tsk_free(tsk); put_signal_struct(tsk->signal); diff --git a/security/capability.c b/security/capability.c index 2984ea4..e4206b5 100644 --- a/security/capability.c +++ b/security/capability.c @@ -359,6 +359,9 @@ static int cap_task_create(unsigned long clone_flags) return 0; } +static void cap_task_free(struct task_struct *task) +{ } + static int cap_cred_alloc_blank(struct cred *cred, gfp_t gfp) { return 0; @@ -955,6 +958,7 @@ void __init security_fixup_ops(struct security_operations *ops) set_to_cap_if_null(ops, file_receive); set_to_cap_if_null(ops, dentry_open); set_to_cap_if_null(ops, task_create); + set_to_cap_if_null(ops, task_free); set_to_cap_if_null(ops, cred_alloc_blank); set_to_cap_if_null(ops, cred_free); set_to_cap_if_null(ops, cred_prepare); diff --git a/security/security.c b/security/security.c index 0c6cc69..49a7227 100644 --- a/security/security.c +++ b/security/security.c @@ -749,6 +749,11 @@ int security_task_create(unsigned long clone_flags) return security_ops->task_create(clone_flags); } +void security_task_free(struct task_struct *task) +{ + security_ops->task_free(task); +} + int security_cred_alloc_blank(struct cred *cred, gfp_t gfp) { return security_ops->cred_alloc_blank(cred, gfp); -- 1.7.0.4
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