From 918112c02aff2bac4cb72dc2feba0cb05305813e Mon Sep 17 00:00:00 2001 From: Greg Kurz Date: Mon, 6 Mar 2017 17:34:01 +0100 Subject: 9pfs: fix O_PATH build break with older glibc versions When O_PATH is used with O_DIRECTORY, it only acts as an optimization: the openat() syscall simply finds the name in the VFS, and doesn't trigger the underlying filesystem. On systems that don't define O_PATH, because they have glibc version 2.13 or older for example, we can safely omit it. We don't want to deactivate O_PATH globally though, in case it is used without O_DIRECTORY. The is done with a dedicated macro. Systems without O_PATH may thus fail to resolve names that involve unreadable directories, compared to newer systems succeeding, but such corner case failure is our only option on those older systems to avoid the security hole of chasing symlinks inappropriately. Signed-off-by: Greg Kurz Reviewed-by: Eric Blake (added last paragraph to changelog as suggested by Eric Blake) Signed-off-by: Greg Kurz --- hw/9pfs/9p-util.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'hw/9pfs/9p-util.h') diff --git a/hw/9pfs/9p-util.h b/hw/9pfs/9p-util.h index 091f3ce..cb7b207 100644 --- a/hw/9pfs/9p-util.h +++ b/hw/9pfs/9p-util.h @@ -22,7 +22,12 @@ static inline void close_preserve_errno(int fd) static inline int openat_dir(int dirfd, const char *name) { - return openat(dirfd, name, O_DIRECTORY | O_RDONLY | O_PATH); +#ifdef O_PATH +#define OPENAT_DIR_O_PATH O_PATH +#else +#define OPENAT_DIR_O_PATH 0 +#endif + return openat(dirfd, name, O_DIRECTORY | O_RDONLY | OPENAT_DIR_O_PATH); } static inline int openat_file(int dirfd, const char *name, int flags, -- cgit v1.1