From 496ad9aa8ef448058e36ca7a787c61f2e63f0f54 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Wed, 23 Jan 2013 17:07:38 -0500 Subject: new helper: file_inode(file) Signed-off-by: Al Viro --- fs/hugetlbfs/inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/hugetlbfs/inode.c') diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index 78bde32ea951..edb42ea60c76 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -97,7 +97,7 @@ static void huge_pagevec_release(struct pagevec *pvec) static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma) { - struct inode *inode = file->f_path.dentry->d_inode; + struct inode *inode = file_inode(file); loff_t len, vma_len; int ret; struct hstate *h = hstate_file(file); -- cgit v1.2.3 From 39b652527457452f09b35044fb4f8b3b0eabafdf Mon Sep 17 00:00:00 2001 From: Anatol Pomozov Date: Wed, 12 Sep 2012 20:11:55 -0700 Subject: fs: Preserve error code in get_empty_filp(), part 2 Allocating a file structure in function get_empty_filp() might fail because of several reasons: - not enough memory for file structures - operation is not allowed - user is over its limit Currently the function returns NULL in all cases and we loose the exact reason of the error. All callers of get_empty_filp() assume that the function can fail with ENFILE only. Return error through pointer. Change all callers to preserve this error code. [AV: cleaned up a bit, carved the get_empty_filp() part out into a separate commit (things remaining here deal with alloc_file()), removed pipe(2) behaviour change] Signed-off-by: Anatol Pomozov Reviewed-by: "Theodore Ts'o" Signed-off-by: Al Viro --- fs/hugetlbfs/inode.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) (limited to 'fs/hugetlbfs/inode.c') diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index edb42ea60c76..99fe7ef2f09b 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -923,8 +923,7 @@ struct file *hugetlb_file_setup(const char *name, unsigned long addr, struct user_struct **user, int creat_flags, int page_size_log) { - int error = -ENOMEM; - struct file *file; + struct file *file = ERR_PTR(-ENOMEM); struct inode *inode; struct path path; struct dentry *root; @@ -964,7 +963,7 @@ struct file *hugetlb_file_setup(const char *name, unsigned long addr, goto out_shm_unlock; path.mnt = mntget(hugetlbfs_vfsmount[hstate_idx]); - error = -ENOSPC; + file = ERR_PTR(-ENOSPC); inode = hugetlbfs_get_inode(root->d_sb, NULL, S_IFREG | S_IRWXUGO, 0); if (!inode) goto out_dentry; @@ -973,7 +972,7 @@ struct file *hugetlb_file_setup(const char *name, unsigned long addr, size += addr & ~huge_page_mask(hstate); num_pages = ALIGN(size, huge_page_size(hstate)) >> huge_page_shift(hstate); - error = -ENOMEM; + file = ERR_PTR(-ENOMEM); if (hugetlb_reserve_pages(inode, 0, num_pages, NULL, acctflag)) goto out_inode; @@ -981,10 +980,9 @@ struct file *hugetlb_file_setup(const char *name, unsigned long addr, inode->i_size = size; clear_nlink(inode); - error = -ENFILE; file = alloc_file(&path, FMODE_WRITE | FMODE_READ, &hugetlbfs_file_operations); - if (!file) + if (IS_ERR(file)) goto out_dentry; /* inode is already attached */ return file; @@ -998,7 +996,7 @@ out_shm_unlock: user_shm_unlock(size, *user); *user = NULL; } - return ERR_PTR(error); + return file; } static int __init init_hugetlbfs_fs(void) -- cgit v1.2.3 From 0df4d6e5bd008a94f1527aa751bbcf7160257c1d Mon Sep 17 00:00:00 2001 From: Al Viro Date: Thu, 14 Feb 2013 22:39:53 -0500 Subject: hugetlb_file_setup(): use d_alloc_pseudo() Signed-off-by: Al Viro --- fs/hugetlbfs/inode.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) (limited to 'fs/hugetlbfs/inode.c') diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index 99fe7ef2f09b..7f94e0cbc69c 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -918,6 +918,16 @@ static int get_hstate_idx(int page_size_log) return h - hstates; } +static char *hugetlb_dname(struct dentry *dentry, char *buffer, int buflen) +{ + return dynamic_dname(dentry, buffer, buflen, "/%s (deleted)", + dentry->d_name.name); +} + +static struct dentry_operations anon_ops = { + .d_dname = hugetlb_dname +}; + struct file *hugetlb_file_setup(const char *name, unsigned long addr, size_t size, vm_flags_t acctflag, struct user_struct **user, @@ -926,7 +936,7 @@ struct file *hugetlb_file_setup(const char *name, unsigned long addr, struct file *file = ERR_PTR(-ENOMEM); struct inode *inode; struct path path; - struct dentry *root; + struct super_block *sb; struct qstr quick_string; struct hstate *hstate; unsigned long num_pages; @@ -954,17 +964,18 @@ struct file *hugetlb_file_setup(const char *name, unsigned long addr, } } - root = hugetlbfs_vfsmount[hstate_idx]->mnt_root; + sb = hugetlbfs_vfsmount[hstate_idx]->mnt_sb; quick_string.name = name; quick_string.len = strlen(quick_string.name); quick_string.hash = 0; - path.dentry = d_alloc(root, &quick_string); + path.dentry = d_alloc_pseudo(sb, &quick_string); if (!path.dentry) goto out_shm_unlock; + d_set_d_op(path.dentry, &anon_ops); path.mnt = mntget(hugetlbfs_vfsmount[hstate_idx]); file = ERR_PTR(-ENOSPC); - inode = hugetlbfs_get_inode(root->d_sb, NULL, S_IFREG | S_IRWXUGO, 0); + inode = hugetlbfs_get_inode(sb, NULL, S_IFREG | S_IRWXUGO, 0); if (!inode) goto out_dentry; -- cgit v1.2.3 From 7f78e0351394052e1a6293e175825eb5c7869507 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Sat, 2 Mar 2013 19:39:14 -0800 Subject: fs: Limit sys_mount to only request filesystem modules. Modify the request_module to prefix the file system type with "fs-" and add aliases to all of the filesystems that can be built as modules to match. A common practice is to build all of the kernel code and leave code that is not commonly needed as modules, with the result that many users are exposed to any bug anywhere in the kernel. Looking for filesystems with a fs- prefix limits the pool of possible modules that can be loaded by mount to just filesystems trivially making things safer with no real cost. Using aliases means user space can control the policy of which filesystem modules are auto-loaded by editing /etc/modprobe.d/*.conf with blacklist and alias directives. Allowing simple, safe, well understood work-arounds to known problematic software. This also addresses a rare but unfortunate problem where the filesystem name is not the same as it's module name and module auto-loading would not work. While writing this patch I saw a handful of such cases. The most significant being autofs that lives in the module autofs4. This is relevant to user namespaces because we can reach the request module in get_fs_type() without having any special permissions, and people get uncomfortable when a user specified string (in this case the filesystem type) goes all of the way to request_module. After having looked at this issue I don't think there is any particular reason to perform any filtering or permission checks beyond making it clear in the module request that we want a filesystem module. The common pattern in the kernel is to call request_module() without regards to the users permissions. In general all a filesystem module does once loaded is call register_filesystem() and go to sleep. Which means there is not much attack surface exposed by loading a filesytem module unless the filesystem is mounted. In a user namespace filesystems are not mounted unless .fs_flags = FS_USERNS_MOUNT, which most filesystems do not set today. Acked-by: Serge Hallyn Acked-by: Kees Cook Reported-by: Kees Cook Signed-off-by: "Eric W. Biederman" --- fs/hugetlbfs/inode.c | 1 + 1 file changed, 1 insertion(+) (limited to 'fs/hugetlbfs/inode.c') diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index 7f94e0cbc69c..84e3d856e91d 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -896,6 +896,7 @@ static struct file_system_type hugetlbfs_fs_type = { .mount = hugetlbfs_mount, .kill_sb = kill_litter_super, }; +MODULE_ALIAS_FS("hugetlbfs"); static struct vfsmount *hugetlbfs_vfsmount[HUGE_MAX_HSTATE]; -- cgit v1.2.3