diff options
authorSeebs <seebs@seebs.net>2018-04-13 16:00:26 -0500
committerSeebs <seebs@seebs.net>2018-04-13 16:03:00 -0500
commitfddbe854c9db058d5a05830d3bcdd4233d95ee2e (patch)
parent3a48dc4373d65bf1203da4899b4dc2bc17993a26 (diff)
Fix symlink following errors
openat() was passing its flags unaltered to pseudo_root_path(), which assumes that a flags argument other than 0 means "don't follow symlinks in last path component". This is completely wrong, and I have no idea how it survived this long unnoticed. Now, if a plain flags variable is set and not overruled by a comment like /* flags=... */, it's masked with AT_SYMLINK_NOFOLLOW, as there are other values fstatat() and friends can take, and the openat() flags are just overridden with 0. (The only meaningful case would be O_NOFOLLOW, but O_NOFOLLOW instructs us to *fail* in the open if the path is a symlink, so we don't care.) Signed-off-by: Seebs <seebs@seebs.net>
3 files changed, 4 insertions, 3 deletions
diff --git a/ChangeLog.txt b/ChangeLog.txt
index 36a1927..d6e3fca 100644
--- a/ChangeLog.txt
+++ b/ChangeLog.txt
@@ -7,6 +7,7 @@
calls to diag() and debug().
* (seebs) Fix a lurking stray slash that could happen while
resolving absolute symlinks.
+ * (seebs) fix mishandled flags for symlink following.
* (seebs) Change default copyright notice in guts to
diff --git a/makewrappers b/makewrappers
index ff08ba0..fa514ba 100755
--- a/makewrappers
+++ b/makewrappers
@@ -275,7 +275,7 @@ class Function:
self.specific_dirfds[arg.name[:-5]] = True
self.dirfd = 'dirfd'
elif arg.name == 'flags':
- self.flags = 'flags'
+ self.flags = '(flags & AT_SYMLINK_NOFOLLOW)'
elif arg.name.endswith('path'):
diff --git a/ports/linux/wrapfuncs.in b/ports/linux/wrapfuncs.in
index 9be6505..e47acc3 100644
--- a/ports/linux/wrapfuncs.in
+++ b/ports/linux/wrapfuncs.in
@@ -5,8 +5,8 @@ int __lxstat(int ver, const char *path, struct stat *buf); /* flags=AT_SYMLINK_N
int __fxstat(int ver, int fd, struct stat *buf);
int lchown(const char *path, uid_t owner, gid_t group); /* flags=AT_SYMLINK_NOFOLLOW */
int __fxstatat(int ver, int dirfd, const char *path, struct stat *buf, int flags);
-int openat(int dirfd, const char *path, int flags, ...{mode_t mode});
-int __openat_2(int dirfd, const char *path, int flags);
+int openat(int dirfd, const char *path, int flags, ...{mode_t mode}); /* flags=0 */
+int __openat_2(int dirfd, const char *path, int flags); /* flags=0 */
int mknod(const char *path, mode_t mode, dev_t dev); /* real_func=pseudo_mknod */
int mknodat(int dirfd, const char *path, mode_t mode, dev_t dev); /* real_func=pseudo_mknodat */
int __xmknod(int ver, const char *path, mode_t mode, dev_t *dev); /* flags=AT_SYMLINK_NOFOLLOW */