From: Andreas Gruenbacher Date: Fri, 3 Nov 2006 06:07:29 +0000 (-0800) Subject: [PATCH] Fix user.* xattr permission check for sticky dirs X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=f1f2d8713d16a1e198880bbc716eb24fae09c858;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git [PATCH] Fix user.* xattr permission check for sticky dirs The user.* extended attributes are only allowed on regular files and directories. Sticky directories further restrict write access to the owner and privileged users. (See the attr(5) man page for an explanation.) The original check in ext2/ext3 when user.* xattrs were merged was more restrictive than intended, and when the xattr permission checks were moved into the VFS, read access to user.* attributes on sticky directores ended up being denied in addition. Originally-from: Gerard Neil Signed-off-by: Andreas Gruenbacher Cc: Dave Kleikamp Cc: Jan Engelhardt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/fs/xattr.c b/fs/xattr.c index 395635100f77..0901bdc2ce24 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -48,14 +48,21 @@ xattr_permission(struct inode *inode, const char *name, int mask) return 0; /* - * The trusted.* namespace can only accessed by a privilegued user. + * The trusted.* namespace can only be accessed by a privileged user. */ if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) return (capable(CAP_SYS_ADMIN) ? 0 : -EPERM); + /* In user.* namespace, only regular files and directories can have + * extended attributes. For sticky directories, only the owner and + * privileged user can write attributes. + */ if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) { - if (!S_ISREG(inode->i_mode) && - (!S_ISDIR(inode->i_mode) || inode->i_mode & S_ISVTX)) + if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode)) + return -EPERM; + if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) && + (mask & MAY_WRITE) && (current->fsuid != inode->i_uid) && + !capable(CAP_FOWNER)) return -EPERM; }