[PATCH v2 05/10] audit: allow audit code to satisfy getname requests from its names_list

Currently, if we call getname() on a userland string more than once, we'll get multiple copies of the string and multiple audit_names records. Add a function that will allow the audit_names code to satisfy getname requests using info from the audit_names list, avoiding a new allocation and audit_names records. Signed-off-by: Jeff Layton <jlayton(a)redhat.com&gt; --- fs/namei.c | 4 ++++ include/linux/audit.h | 8 ++++++++ kernel/auditsc.c | 23 +++++++++++++++++++++++ 3 files changed, 35 insertions(+) diff --git a/fs/namei.c b/fs/namei.c index 60db390..01a2dd18 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -130,6 +130,10 @@ getname_flags(const char __user *filename, int flags, int *empty) char *kname; int len; + result = audit_reusename(filename); + if (result) + return result; + /* FIXME: create dedicated slabcache? */ result = kzalloc(sizeof(*result), GFP_KERNEL); if (unlikely(!result)) diff --git a/include/linux/audit.h b/include/linux/audit.h index d361921..ea58de3 100644 --- a/include/linux/audit.h +++ b/include/linux/audit.h @@ -469,6 +469,7 @@ extern void __audit_syscall_entry(int arch, int major, unsigned long a0, unsigned long a1, unsigned long a2, unsigned long a3); extern void __audit_syscall_exit(int ret_success, long ret_value); +extern struct getname_info *__audit_reusename(const __user char *uptr); extern void __audit_getname(struct getname_info *ginfo); extern void audit_putname(struct getname_info *ginfo); extern void __audit_inode(const char *name, const struct dentry *dentry, @@ -505,6 +506,12 @@ static inline void audit_syscall_exit(void *pt_regs) __audit_syscall_exit(success, return_code); } } +static inline struct getname_info *audit_reusename(const __user char *name) +{ + if (unlikely(!audit_dummy_context())) + return __audit_reusename(name); + return NULL; +} static inline void audit_getname(struct getname_info *name) { if (unlikely(!audit_dummy_context())) @@ -642,6 +649,7 @@ extern int audit_signals; #define audit_syscall_entry(ta,a,b,c,d,e) do { ; } while (0) #define audit_syscall_exit(r) do { ; } while (0) #define audit_dummy_context() 1 +#define audit_reusename(g) ({ NULL; }) #define audit_getname(n) do { ; } while (0) #define audit_putname(n) do { ; } while (0) #define __audit_inode(n,d,p) do { ; } while (0) diff --git a/kernel/auditsc.c b/kernel/auditsc.c index 0ba346b..89974ca 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -2035,6 +2035,29 @@ static struct audit_names *audit_alloc_name(struct audit_context *context, } /** + * audit_reusename - fill out getname_info with info from existing entry + * @uptr: userland ptr to pathname + * + * Search the audit_names list for the current audit context. If there is an + * existing entry with a matching "uptr" then return the getname_info + * associated with that audit_name. If not, return NULL. + */ +struct getname_info * +__audit_reusename(const __user char *uptr) +{ + struct audit_context *context = current->audit_context; + struct audit_names *n; + + list_for_each_entry(n, &context->names_list, list) { + if (!n->ginfo) + continue; + if (n->ginfo->uptr == uptr) + return n->ginfo; + } + return NULL; +} + +/** * audit_getname - add a name to the list * @name: name to add * -- 1.7.11.4