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lsattr,chattr: do not open e.g. device files unless asked directly; do not follow links

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Add O_NOFOLLOW (and O_NOCTTY for good measure) to open calls like e2fsprogs does.

In lsattr, when recursing, operate only on regular files, symlinks, and directories.
(Otherwise, "lsattr /dev" can e.g. open a watchdog device... not good).

At this time, looks like chattr/lsattr can't operate on symlink inodes -
ioctls do not work on open(O_PATH | O_NOFOLLOW) fds.

function                                             old     new   delta
lsattr_dir_proc                                      168     203     +35
change_attributes                                    410     408      -2
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/1 up/down: 35/-2)              Total: 33 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2021-06-24 01:07:56 +02:00
parent 0e55af6c61
commit 9468ea06d2
2 changed files with 18 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
e2fsprogs/chattr.c
View File

@ -162,8 +162,6 @@ static void change_attributes(const char *name, struct globals *gp)
bb_perror_msg("can't stat '%s'", name);
return;
}
if (S_ISLNK(st.st_mode) && gp->recursive)
return;
/* Don't try to open device files, fifos etc. We probably
* ought to display an error if the file was explicitly given
@ -172,7 +170,12 @@ static void change_attributes(const char *name, struct globals *gp)
if (!S_ISREG(st.st_mode) && !S_ISLNK(st.st_mode) && !S_ISDIR(st.st_mode))
return;
fd = open_or_warn(name, O_RDONLY | O_NONBLOCK); /* neither read nor write asked for */
/* There is no way to run needed ioctls on a symlink.
* open(O_PATH | O_NOFOLLOW) _can_ be used to get a fd referring to the symlink,
* but ioctls fail on such a fd (tried on 4.12.0 kernel).
* e2fsprogs-1.46.2 uses open(O_NOFOLLOW), it fails on symlinks.
*/
fd = open_or_warn(name, O_RDONLY | O_NONBLOCK | O_NOCTTY | O_NOFOLLOW);
if (fd >= 0) {
int r;

15
e2fsprogs/lsattr.c
View File

@ -49,8 +49,13 @@ static void list_attributes(const char *name)
unsigned fsflags;
int fd, r;
fd = open_or_warn(name, O_RDONLY | O_NONBLOCK); /* neither read nor write asked for */
if (fd < 0) /* for example, dangling links */
/* There is no way to run needed ioctls on a symlink.
* open(O_PATH | O_NOFOLLOW) _can_ be used to get a fd referring to the symlink,
* but ioctls fail on such a fd (tried on 4.12.0 kernel).
* e2fsprogs-1.46.2 uses open(O_NOFOLLOW), it fails on symlinks.
*/
fd = open_or_warn(name, O_RDONLY | O_NONBLOCK | O_NOCTTY | O_NOFOLLOW);
if (fd < 0)
return;
if (option_mask32 & OPT_PROJID) {
@ -102,8 +107,12 @@ static int FAST_FUNC lsattr_dir_proc(const char *dir_name,
if (lstat(path, &st) != 0)
bb_perror_msg("can't stat '%s'", path);
else if (de->d_name[0] != '.' || (option_mask32 & OPT_ALL)) {
list_attributes(path);
/* Don't try to open device files, fifos etc */
if (S_ISREG(st.st_mode) || S_ISLNK(st.st_mode) || S_ISDIR(st.st_mode))
list_attributes(path);
if (S_ISDIR(st.st_mode) && (option_mask32 & OPT_RECUR)
&& !DOT_OR_DOTDOT(de->d_name)
) {