diff options
Diffstat (limited to 'fs/namei.c')
| -rw-r--r-- | fs/namei.c | 25 |
1 files changed, 22 insertions, 3 deletions
diff --git a/fs/namei.c b/fs/namei.c index 2e7c4bff6..ab8d6089e 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -73,6 +73,10 @@ * and in the old Linux semantics. */ +/* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink + * semantics. See the comments in "open_namei" and "do_link" below. + */ + static char * quicklist = NULL; static int quickcount = 0; struct semaphore quicklock = MUTEX; @@ -530,7 +534,13 @@ struct dentry * open_namei(const char * pathname, int flag, int mode) mode &= S_IALLUGO & ~current->fs->umask; mode |= S_IFREG; - dentry = lookup_dentry(pathname, NULL, 1); + /* + * Special case: O_CREAT|O_EXCL on a dangling symlink should + * give EEXIST for security reasons. While inconsistent, this + * is the same scheme used by, for example, Solaris 2.5.1. --KAB + */ + dentry = lookup_dentry(pathname, NULL, + (flag & (O_CREAT|O_EXCL)) != (O_CREAT|O_EXCL)); if (IS_ERR(dentry)) return dentry; @@ -731,7 +741,7 @@ static inline int do_mkdir(const char * pathname, int mode) struct dentry *dir; struct dentry *dentry; - dentry = lookup_dentry(pathname, NULL, 1); + dentry = lookup_dentry(pathname, NULL, 0); error = PTR_ERR(dentry); if (IS_ERR(dentry)) goto exit; @@ -1010,7 +1020,16 @@ static inline int do_link(const char * oldname, const char * newname) if (IS_ERR(old_dentry)) goto exit; - new_dentry = lookup_dentry(newname, NULL, 1); + /* + * Hardlinks are often used in delicate situations. We avoid + * security-related surprises by not following symlinks on the + * newname. We *do* follow them on the oldname. This is + * the same as Digital Unix 4.0, for example. + * + * Solaris 2.5.1 is similar, but for a laugh try linking from + * a dangling symlink. --KAB + */ + new_dentry = lookup_dentry(newname, NULL, 0); error = PTR_ERR(new_dentry); if (IS_ERR(new_dentry)) goto exit_old; |