From f52e0c11305aa09ed56cad97ffc8f0cdc3d78b5d Mon Sep 17 00:00:00 2001 From: Al Viro Date: Mon, 14 Mar 2011 18:56:51 -0400 Subject: [PATCH] New AT_... flag: AT_EMPTY_PATH For name_to_handle_at(2) we'll want both ...at()-style syscall that would be usable for non-directory descriptors (with empty relative pathname). Introduce new flag (AT_EMPTY_PATH) to deal with that and corresponding LOOKUP_EMPTY; teach user_path_at() and path_init() to deal with the latter. Signed-off-by: Al Viro --- fs/namei.c | 29 +++++++++++++++++++---------- include/linux/fcntl.h | 1 + include/linux/namei.h | 1 + 3 files changed, 21 insertions(+), 10 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index abc8d2df121..83e92bab79a 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -136,7 +136,7 @@ static int do_getname(const char __user *filename, char *page) return retval; } -char * getname(const char __user * filename) +static char *getname_flags(const char __user * filename, int flags) { char *tmp, *result; @@ -147,14 +147,21 @@ char * getname(const char __user * filename) result = tmp; if (retval < 0) { - __putname(tmp); - result = ERR_PTR(retval); + if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) { + __putname(tmp); + result = ERR_PTR(retval); + } } } audit_getname(result); return result; } +char *getname(const char __user * filename) +{ + return getname_flags(filename, 0); +} + #ifdef CONFIG_AUDITSYSCALL void putname(const char *name) { @@ -1544,13 +1551,15 @@ static int path_init(int dfd, const char *name, unsigned int flags, dentry = file->f_path.dentry; - retval = -ENOTDIR; - if (!S_ISDIR(dentry->d_inode->i_mode)) - goto fput_fail; + if (*name) { + retval = -ENOTDIR; + if (!S_ISDIR(dentry->d_inode->i_mode)) + goto fput_fail; - retval = file_permission(file, MAY_EXEC); - if (retval) - goto fput_fail; + retval = file_permission(file, MAY_EXEC); + if (retval) + goto fput_fail; + } nd->path = file->f_path; if (flags & LOOKUP_RCU) { @@ -1759,7 +1768,7 @@ int user_path_at(int dfd, const char __user *name, unsigned flags, struct path *path) { struct nameidata nd; - char *tmp = getname(name); + char *tmp = getname_flags(name, flags); int err = PTR_ERR(tmp); if (!IS_ERR(tmp)) { diff --git a/include/linux/fcntl.h b/include/linux/fcntl.h index a562fa5fb4e..f550f894ba1 100644 --- a/include/linux/fcntl.h +++ b/include/linux/fcntl.h @@ -46,6 +46,7 @@ unlinking file. */ #define AT_SYMLINK_FOLLOW 0x400 /* Follow symbolic links. */ #define AT_NO_AUTOMOUNT 0x800 /* Suppress terminal automount traversal */ +#define AT_EMPTY_PATH 0x1000 /* Allow empty relative pathname */ #ifdef __KERNEL__ diff --git a/include/linux/namei.h b/include/linux/namei.h index 83cd6e5cd7d..9c8603872c3 100644 --- a/include/linux/namei.h +++ b/include/linux/namei.h @@ -64,6 +64,7 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND}; #define LOOKUP_JUMPED 0x1000 #define LOOKUP_ROOT 0x2000 +#define LOOKUP_EMPTY 0x4000 extern int user_path_at(int, const char __user *, unsigned, struct path *); -- 2.20.1