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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>
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parent
8788a17c23
commit
bdd8f62431
32
fs/exec.c
32
fs/exec.c
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@ -904,6 +904,10 @@ EXPORT_SYMBOL(transfer_args_to_stack);
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#endif /* CONFIG_MMU */
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/*
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* On success, caller must call do_close_execat() on the returned
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* struct file to close it.
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*/
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static struct file *do_open_execat(int fd, struct filename *name, int flags)
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{
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struct file *file;
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@ -948,6 +952,17 @@ static struct file *do_open_execat(int fd, struct filename *name, int flags)
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return ERR_PTR(err);
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}
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/**
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* open_exec - Open a path name for execution
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*
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* @name: path name to open with the intent of executing it.
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*
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* Returns ERR_PTR on failure or allocated struct file on success.
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*
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* As this is a wrapper for the internal do_open_execat(), callers
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* must call allow_write_access() before fput() on release. Also see
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* do_close_execat().
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*/
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struct file *open_exec(const char *name)
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{
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struct filename *filename = getname_kernel(name);
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@ -1484,6 +1499,15 @@ static int prepare_bprm_creds(struct linux_binprm *bprm)
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return -ENOMEM;
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}
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/* Matches do_open_execat() */
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static void do_close_execat(struct file *file)
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{
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if (!file)
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return;
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allow_write_access(file);
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fput(file);
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}
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static void free_bprm(struct linux_binprm *bprm)
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{
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if (bprm->mm) {
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@ -1495,10 +1519,7 @@ static void free_bprm(struct linux_binprm *bprm)
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mutex_unlock(¤t->signal->cred_guard_mutex);
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abort_creds(bprm->cred);
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}
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if (bprm->file) {
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allow_write_access(bprm->file);
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fput(bprm->file);
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}
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do_close_execat(bprm->file);
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if (bprm->executable)
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fput(bprm->executable);
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/* If a binfmt changed the interp, free it. */
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@ -1520,8 +1541,7 @@ static struct linux_binprm *alloc_bprm(int fd, struct filename *filename, int fl
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bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
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if (!bprm) {
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allow_write_access(file);
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fput(file);
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do_close_execat(file);
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return ERR_PTR(-ENOMEM);
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}
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