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authorKees Cook <keescook@chromium.org>2022-09-16 17:11:18 -0700
committerKees Cook <keescook@chromium.org>2024-01-22 11:45:39 -0800
commitbdd8f62431ebcf15902a5fce3336388e436405c6 (patch)
treeefbc4718f1dfcf8341d5f4b895fdd264d284fca3 /fs/exec.c
parent8788a17c2319f020ccdc3f2907179a5ae81b7ad6 (diff)
exec: Add do_close_execat() helper
Consolidate the calls to allow_write_access()/fput() into a single place, since we repeat this code pattern. Add comments around the callers for the details on it. Link: https://lore.kernel.org/r/202209161637.9EDAF6B18@keescook Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'fs/exec.c')
-rw-r--r--fs/exec.c32
1 files changed, 26 insertions, 6 deletions
diff --git a/fs/exec.c b/fs/exec.c
index ba7d0548ac57..2037cc636036 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -904,6 +904,10 @@ EXPORT_SYMBOL(transfer_args_to_stack);
#endif /* CONFIG_MMU */
+/*
+ * On success, caller must call do_close_execat() on the returned
+ * struct file to close it.
+ */
static struct file *do_open_execat(int fd, struct filename *name, int flags)
{
struct file *file;
@@ -948,6 +952,17 @@ exit:
return ERR_PTR(err);
}
+/**
+ * open_exec - Open a path name for execution
+ *
+ * @name: path name to open with the intent of executing it.
+ *
+ * Returns ERR_PTR on failure or allocated struct file on success.
+ *
+ * As this is a wrapper for the internal do_open_execat(), callers
+ * must call allow_write_access() before fput() on release. Also see
+ * do_close_execat().
+ */
struct file *open_exec(const char *name)
{
struct filename *filename = getname_kernel(name);
@@ -1484,6 +1499,15 @@ static int prepare_bprm_creds(struct linux_binprm *bprm)
return -ENOMEM;
}
+/* Matches do_open_execat() */
+static void do_close_execat(struct file *file)
+{
+ if (!file)
+ return;
+ allow_write_access(file);
+ fput(file);
+}
+
static void free_bprm(struct linux_binprm *bprm)
{
if (bprm->mm) {
@@ -1495,10 +1519,7 @@ static void free_bprm(struct linux_binprm *bprm)
mutex_unlock(&current->signal->cred_guard_mutex);
abort_creds(bprm->cred);
}
- if (bprm->file) {
- allow_write_access(bprm->file);
- fput(bprm->file);
- }
+ do_close_execat(bprm->file);
if (bprm->executable)
fput(bprm->executable);
/* If a binfmt changed the interp, free it. */
@@ -1520,8 +1541,7 @@ static struct linux_binprm *alloc_bprm(int fd, struct filename *filename, int fl
bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
if (!bprm) {
- allow_write_access(file);
- fput(file);
+ do_close_execat(file);
return ERR_PTR(-ENOMEM);
}