diff options
Diffstat (limited to 'fs/overlayfs')
-rw-r--r-- | fs/overlayfs/export.c | 6 | ||||
-rw-r--r-- | fs/overlayfs/file.c | 4 | ||||
-rw-r--r-- | fs/overlayfs/namei.c | 116 | ||||
-rw-r--r-- | fs/overlayfs/overlayfs.h | 10 | ||||
-rw-r--r-- | fs/overlayfs/ovl_entry.h | 2 | ||||
-rw-r--r-- | fs/overlayfs/params.c | 40 | ||||
-rw-r--r-- | fs/overlayfs/readdir.c | 25 | ||||
-rw-r--r-- | fs/overlayfs/util.c | 9 |
8 files changed, 113 insertions, 99 deletions
diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c index 444aeeccb6da..83f80fdb1567 100644 --- a/fs/overlayfs/export.c +++ b/fs/overlayfs/export.c @@ -385,11 +385,9 @@ static struct dentry *ovl_lookup_real_one(struct dentry *connected, */ take_dentry_name_snapshot(&name, real); /* - * No idmap handling here: it's an internal lookup. Could skip - * permission checking altogether, but for now just use non-idmap - * transformed ids. + * No idmap handling here: it's an internal lookup. */ - this = lookup_one_len(name.name.name, connected, name.name.len); + this = lookup_noperm(&name.name, connected); release_dentry_name_snapshot(&name); err = PTR_ERR(this); if (IS_ERR(this)) { diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c index 969b458100fe..dfea7bd800cb 100644 --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -48,8 +48,8 @@ static struct file *ovl_open_realfile(const struct file *file, if (!inode_owner_or_capable(real_idmap, realinode)) flags &= ~O_NOATIME; - realfile = backing_file_open(&file->f_path, flags, realpath, - current_cred()); + realfile = backing_file_open(file_user_path((struct file *) file), + flags, realpath, current_cred()); } ovl_revert_creds(old_cred); diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c index be5c65d6f848..2043f0369059 100644 --- a/fs/overlayfs/namei.c +++ b/fs/overlayfs/namei.c @@ -16,6 +16,7 @@ struct ovl_lookup_data { struct super_block *sb; + struct dentry *dentry; const struct ovl_layer *layer; struct qstr name; bool is_dir; @@ -24,6 +25,7 @@ struct ovl_lookup_data { bool stop; bool last; char *redirect; + char *upperredirect; int metacopy; /* Referring to last redirect xattr */ bool absolute_redirect; @@ -205,8 +207,8 @@ static struct dentry *ovl_lookup_positive_unlocked(struct ovl_lookup_data *d, struct dentry *base, int len, bool drop_negative) { - struct dentry *ret = lookup_one_unlocked(mnt_idmap(d->layer->mnt), name, - base, len); + struct dentry *ret = lookup_one_unlocked(mnt_idmap(d->layer->mnt), + &QSTR_LEN(name, len), base); if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { if (drop_negative && ret->d_lockref.count == 1) { @@ -757,7 +759,7 @@ struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh) if (err) return ERR_PTR(err); - index = lookup_positive_unlocked(name.name, ofs->workdir, name.len); + index = lookup_noperm_positive_unlocked(&name, ofs->workdir); kfree(name.name); if (IS_ERR(index)) { if (PTR_ERR(index) == -ENOENT) @@ -789,8 +791,8 @@ struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper, if (err) return ERR_PTR(err); - index = lookup_one_positive_unlocked(ovl_upper_mnt_idmap(ofs), name.name, - ofs->workdir, name.len); + index = lookup_one_positive_unlocked(ovl_upper_mnt_idmap(ofs), &name, + ofs->workdir); if (IS_ERR(index)) { err = PTR_ERR(index); if (err == -ENOENT) { @@ -1024,6 +1026,31 @@ int ovl_verify_lowerdata(struct dentry *dentry) return ovl_maybe_validate_verity(dentry); } +/* + * Following redirects/metacopy can have security consequences: it's like a + * symlink into the lower layer without the permission checks. + * + * This is only a problem if the upper layer is untrusted (e.g comes from an USB + * drive). This can allow a non-readable file or directory to become readable. + * + * Only following redirects when redirects are enabled disables this attack + * vector when not necessary. + */ +static bool ovl_check_follow_redirect(struct ovl_lookup_data *d) +{ + struct ovl_fs *ofs = OVL_FS(d->sb); + + if (d->metacopy && !ofs->config.metacopy) { + pr_warn_ratelimited("refusing to follow metacopy origin for (%pd2)\n", d->dentry); + return false; + } + if ((d->redirect || d->upperredirect) && !ovl_redirect_follow(ofs)) { + pr_warn_ratelimited("refusing to follow redirect for (%pd2)\n", d->dentry); + return false; + } + return true; +} + struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) { @@ -1039,7 +1066,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, unsigned int ctr = 0; struct inode *inode = NULL; bool upperopaque = false; - char *upperredirect = NULL; + bool check_redirect = (ovl_redirect_follow(ofs) || ofs->numdatalayer); struct dentry *this; unsigned int i; int err; @@ -1047,12 +1074,14 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, int metacopy_size = 0; struct ovl_lookup_data d = { .sb = dentry->d_sb, + .dentry = dentry, .name = dentry->d_name, .is_dir = false, .opaque = false, .stop = false, - .last = ovl_redirect_follow(ofs) ? false : !ovl_numlower(poe), + .last = check_redirect ? false : !ovl_numlower(poe), .redirect = NULL, + .upperredirect = NULL, .metacopy = 0, }; @@ -1094,8 +1123,8 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, if (d.redirect) { err = -ENOMEM; - upperredirect = kstrdup(d.redirect, GFP_KERNEL); - if (!upperredirect) + d.upperredirect = kstrdup(d.redirect, GFP_KERNEL); + if (!d.upperredirect) goto out_put_upper; if (d.redirect[0] == '/') poe = roe; @@ -1113,7 +1142,12 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, for (i = 0; !d.stop && i < ovl_numlower(poe); i++) { struct ovl_path lower = ovl_lowerstack(poe)[i]; - if (!ovl_redirect_follow(ofs)) + if (!ovl_check_follow_redirect(&d)) { + err = -EPERM; + goto out_put; + } + + if (!check_redirect) d.last = i == ovl_numlower(poe) - 1; else if (d.is_dir || !ofs->numdatalayer) d.last = lower.layer->idx == ovl_numlower(roe); @@ -1126,13 +1160,6 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, if (!this) continue; - if ((uppermetacopy || d.metacopy) && !ofs->config.metacopy) { - dput(this); - err = -EPERM; - pr_warn_ratelimited("refusing to follow metacopy origin for (%pd2)\n", dentry); - goto out_put; - } - /* * If no origin fh is stored in upper of a merge dir, store fh * of lower dir and set upper parent "impure". @@ -1185,23 +1212,6 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, ctr++; } - /* - * Following redirects can have security consequences: it's like - * a symlink into the lower layer without the permission checks. - * This is only a problem if the upper layer is untrusted (e.g - * comes from an USB drive). This can allow a non-readable file - * or directory to become readable. - * - * Only following redirects when redirects are enabled disables - * this attack vector when not necessary. - */ - err = -EPERM; - if (d.redirect && !ovl_redirect_follow(ofs)) { - pr_warn_ratelimited("refusing to follow redirect for (%pd2)\n", - dentry); - goto out_put; - } - if (d.stop) break; @@ -1212,10 +1222,16 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, } } - /* Defer lookup of lowerdata in data-only layers to first access */ + /* + * Defer lookup of lowerdata in data-only layers to first access. + * Don't require redirect=follow and metacopy=on in this case. + */ if (d.metacopy && ctr && ofs->numdatalayer && d.absolute_redirect) { d.metacopy = 0; ctr++; + } else if (!ovl_check_follow_redirect(&d)) { + err = -EPERM; + goto out_put; } /* @@ -1298,20 +1314,26 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, /* * It's safe to assign upperredirect here: the previous - * assignment of happens only if upperdentry is non-NULL, and + * assignment happens only if upperdentry is non-NULL, and * this one only if upperdentry is NULL. */ - upperredirect = ovl_get_redirect_xattr(ofs, &upperpath, 0); - if (IS_ERR(upperredirect)) { - err = PTR_ERR(upperredirect); - upperredirect = NULL; + d.upperredirect = ovl_get_redirect_xattr(ofs, &upperpath, 0); + if (IS_ERR(d.upperredirect)) { + err = PTR_ERR(d.upperredirect); + d.upperredirect = NULL; goto out_free_oe; } + err = ovl_check_metacopy_xattr(ofs, &upperpath, NULL); if (err < 0) goto out_free_oe; - uppermetacopy = err; + d.metacopy = uppermetacopy = err; metacopy_size = err; + + if (!ovl_check_follow_redirect(&d)) { + err = -EPERM; + goto out_free_oe; + } } if (upperdentry || ctr) { @@ -1319,7 +1341,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, .upperdentry = upperdentry, .oe = oe, .index = index, - .redirect = upperredirect, + .redirect = d.upperredirect, }; /* Store lowerdata redirect for lazy lookup */ @@ -1361,7 +1383,7 @@ out_put_upper: kfree(origin_path); } dput(upperdentry); - kfree(upperredirect); + kfree(d.upperredirect); out: kfree(d.redirect); ovl_revert_creds(old_cred); @@ -1394,9 +1416,15 @@ bool ovl_lower_positive(struct dentry *dentry) struct dentry *this; struct ovl_path *parentpath = &ovl_lowerstack(poe)[i]; + /* + * We need to make a non-const copy of dentry->d_name, + * because lookup_one_positive_unlocked() will hash name + * with parentpath base, which is on another (lower fs). + */ this = lookup_one_positive_unlocked( mnt_idmap(parentpath->layer->mnt), - name->name, parentpath->dentry, name->len); + &QSTR_LEN(name->name, name->len), + parentpath->dentry); if (IS_ERR(this)) { switch (PTR_ERR(this)) { case -ENOENT: diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index aef942a758ce..497323128e5f 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -246,9 +246,11 @@ static inline struct dentry *ovl_do_mkdir(struct ovl_fs *ofs, struct dentry *dentry, umode_t mode) { - dentry = vfs_mkdir(ovl_upper_mnt_idmap(ofs), dir, dentry, mode); - pr_debug("mkdir(%pd2, 0%o) = %i\n", dentry, mode, PTR_ERR_OR_ZERO(dentry)); - return dentry; + struct dentry *ret; + + ret = vfs_mkdir(ovl_upper_mnt_idmap(ofs), dir, dentry, mode); + pr_debug("mkdir(%pd2, 0%o) = %i\n", dentry, mode, PTR_ERR_OR_ZERO(ret)); + return ret; } static inline int ovl_do_mknod(struct ovl_fs *ofs, @@ -402,7 +404,7 @@ static inline struct dentry *ovl_lookup_upper(struct ovl_fs *ofs, const char *name, struct dentry *base, int len) { - return lookup_one(ovl_upper_mnt_idmap(ofs), name, base, len); + return lookup_one(ovl_upper_mnt_idmap(ofs), &QSTR_LEN(name, len), base); } static inline bool ovl_open_flags_need_copy_up(int flags) diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h index cb449ab310a7..afb7762f873f 100644 --- a/fs/overlayfs/ovl_entry.h +++ b/fs/overlayfs/ovl_entry.h @@ -51,7 +51,7 @@ struct ovl_path { struct ovl_entry { unsigned int __numlower; - struct ovl_path __lowerstack[]; + struct ovl_path __lowerstack[] __counted_by(__numlower); }; /* private information held for overlayfs's superblock */ diff --git a/fs/overlayfs/params.c b/fs/overlayfs/params.c index 6759f7d040c8..f42488c01957 100644 --- a/fs/overlayfs/params.c +++ b/fs/overlayfs/params.c @@ -871,18 +871,6 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx, config->uuid = OVL_UUID_NULL; } - /* Resolve verity -> metacopy dependency */ - if (config->verity_mode && !config->metacopy) { - /* Don't allow explicit specified conflicting combinations */ - if (set.metacopy) { - pr_err("conflicting options: metacopy=off,verity=%s\n", - ovl_verity_mode(config)); - return -EINVAL; - } - /* Otherwise automatically enable metacopy. */ - config->metacopy = true; - } - /* * This is to make the logic below simpler. It doesn't make any other * difference, since redirect_dir=on is only used for upper. @@ -890,18 +878,13 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx, if (!config->upperdir && config->redirect_mode == OVL_REDIRECT_FOLLOW) config->redirect_mode = OVL_REDIRECT_ON; - /* Resolve verity -> metacopy -> redirect_dir dependency */ + /* metacopy -> redirect_dir dependency */ if (config->metacopy && config->redirect_mode != OVL_REDIRECT_ON) { if (set.metacopy && set.redirect) { pr_err("conflicting options: metacopy=on,redirect_dir=%s\n", ovl_redirect_mode(config)); return -EINVAL; } - if (config->verity_mode && set.redirect) { - pr_err("conflicting options: verity=%s,redirect_dir=%s\n", - ovl_verity_mode(config), ovl_redirect_mode(config)); - return -EINVAL; - } if (set.redirect) { /* * There was an explicit redirect_dir=... that resulted @@ -970,7 +953,7 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx, } - /* Resolve userxattr -> !redirect && !metacopy && !verity dependency */ + /* Resolve userxattr -> !redirect && !metacopy dependency */ if (config->userxattr) { if (set.redirect && config->redirect_mode != OVL_REDIRECT_NOFOLLOW) { @@ -982,11 +965,6 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx, pr_err("conflicting options: userxattr,metacopy=on\n"); return -EINVAL; } - if (config->verity_mode) { - pr_err("conflicting options: userxattr,verity=%s\n", - ovl_verity_mode(config)); - return -EINVAL; - } /* * Silently disable default setting of redirect and metacopy. * This shall be the default in the future as well: these @@ -1025,11 +1003,6 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx, */ } - if (ctx->nr_data > 0 && !config->metacopy) { - pr_err("lower data-only dirs require metacopy support.\n"); - return -EINVAL; - } - return 0; } @@ -1078,17 +1051,16 @@ int ovl_show_options(struct seq_file *m, struct dentry *dentry) seq_printf(m, ",redirect_dir=%s", ovl_redirect_mode(&ofs->config)); if (ofs->config.index != ovl_index_def) - seq_printf(m, ",index=%s", ofs->config.index ? "on" : "off"); + seq_printf(m, ",index=%s", str_on_off(ofs->config.index)); if (ofs->config.uuid != ovl_uuid_def()) seq_printf(m, ",uuid=%s", ovl_uuid_mode(&ofs->config)); if (ofs->config.nfs_export != ovl_nfs_export_def) - seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ? - "on" : "off"); + seq_printf(m, ",nfs_export=%s", + str_on_off(ofs->config.nfs_export)); if (ofs->config.xino != ovl_xino_def() && !ovl_same_fs(ofs)) seq_printf(m, ",xino=%s", ovl_xino_mode(&ofs->config)); if (ofs->config.metacopy != ovl_metacopy_def) - seq_printf(m, ",metacopy=%s", - ofs->config.metacopy ? "on" : "off"); + seq_printf(m, ",metacopy=%s", str_on_off(ofs->config.metacopy)); if (ofs->config.ovl_volatile) seq_puts(m, ",volatile"); if (ofs->config.userxattr) diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c index 881ec5592da5..474c80d210d1 100644 --- a/fs/overlayfs/readdir.c +++ b/fs/overlayfs/readdir.c @@ -13,6 +13,7 @@ #include <linux/security.h> #include <linux/cred.h> #include <linux/ratelimit.h> +#include <linux/overflow.h> #include "overlayfs.h" struct ovl_cache_entry { @@ -147,9 +148,8 @@ static struct ovl_cache_entry *ovl_cache_entry_new(struct ovl_readdir_data *rdd, u64 ino, unsigned int d_type) { struct ovl_cache_entry *p; - size_t size = offsetof(struct ovl_cache_entry, name[len + 1]); - p = kmalloc(size, GFP_KERNEL); + p = kmalloc(struct_size(p, name, len + 1), GFP_KERNEL); if (!p) return NULL; @@ -271,7 +271,6 @@ static bool ovl_fill_merge(struct dir_context *ctx, const char *name, static int ovl_check_whiteouts(const struct path *path, struct ovl_readdir_data *rdd) { int err; - struct ovl_cache_entry *p; struct dentry *dentry, *dir = path->dentry; const struct cred *old_cred; @@ -280,9 +279,11 @@ static int ovl_check_whiteouts(const struct path *path, struct ovl_readdir_data err = down_write_killable(&dir->d_inode->i_rwsem); if (!err) { while (rdd->first_maybe_whiteout) { - p = rdd->first_maybe_whiteout; + struct ovl_cache_entry *p = + rdd->first_maybe_whiteout; rdd->first_maybe_whiteout = p->next_maybe_whiteout; - dentry = lookup_one(mnt_idmap(path->mnt), p->name, dir, p->len); + dentry = lookup_one(mnt_idmap(path->mnt), + &QSTR_LEN(p->name, p->len), dir); if (!IS_ERR(dentry)) { p->is_whiteout = ovl_is_whiteout(dentry); dput(dentry); @@ -351,6 +352,7 @@ static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list, struct path realpath; struct ovl_readdir_data rdd = { .ctx.actor = ovl_fill_merge, + .ctx.count = INT_MAX, .dentry = dentry, .list = list, .root = root, @@ -492,7 +494,7 @@ static int ovl_cache_update(const struct path *path, struct ovl_cache_entry *p, } } /* This checks also for xwhiteouts */ - this = lookup_one(mnt_idmap(path->mnt), p->name, dir, p->len); + this = lookup_one(mnt_idmap(path->mnt), &QSTR_LEN(p->name, p->len), dir); if (IS_ERR_OR_NULL(this) || !this->d_inode) { /* Mark a stale entry */ p->is_whiteout = true; @@ -571,6 +573,7 @@ static int ovl_dir_read_impure(const struct path *path, struct list_head *list, struct ovl_cache_entry *p, *n; struct ovl_readdir_data rdd = { .ctx.actor = ovl_fill_plain, + .ctx.count = INT_MAX, .list = list, .root = root, }; @@ -672,6 +675,7 @@ static bool ovl_fill_real(struct dir_context *ctx, const char *name, struct ovl_readdir_translate *rdt = container_of(ctx, struct ovl_readdir_translate, ctx); struct dir_context *orig_ctx = rdt->orig_ctx; + bool res; if (rdt->parent_ino && strcmp(name, "..") == 0) { ino = rdt->parent_ino; @@ -686,7 +690,10 @@ static bool ovl_fill_real(struct dir_context *ctx, const char *name, name, namelen, rdt->xinowarn); } - return orig_ctx->actor(orig_ctx, name, namelen, offset, ino, d_type); + res = orig_ctx->actor(orig_ctx, name, namelen, offset, ino, d_type); + ctx->count = orig_ctx->count; + + return res; } static bool ovl_is_impure_dir(struct file *file) @@ -713,6 +720,7 @@ static int ovl_iterate_real(struct file *file, struct dir_context *ctx) const struct ovl_layer *lower_layer = ovl_layer_lower(dir); struct ovl_readdir_translate rdt = { .ctx.actor = ovl_fill_real, + .ctx.count = ctx->count, .orig_ctx = ctx, .xinobits = ovl_xino_bits(ofs), .xinowarn = ovl_xino_warn(ofs), @@ -1073,6 +1081,7 @@ int ovl_check_d_type_supported(const struct path *realpath) int err; struct ovl_readdir_data rdd = { .ctx.actor = ovl_check_d_type, + .ctx.count = INT_MAX, .d_type_supported = false, }; @@ -1094,6 +1103,7 @@ static int ovl_workdir_cleanup_recurse(struct ovl_fs *ofs, const struct path *pa struct ovl_cache_entry *p; struct ovl_readdir_data rdd = { .ctx.actor = ovl_fill_plain, + .ctx.count = INT_MAX, .list = &list, }; bool incompat = false; @@ -1178,6 +1188,7 @@ int ovl_indexdir_cleanup(struct ovl_fs *ofs) struct ovl_cache_entry *p; struct ovl_readdir_data rdd = { .ctx.actor = ovl_fill_plain, + .ctx.count = INT_MAX, .list = &list, }; diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c index 0819c739cc2f..dcccb4b4a66c 100644 --- a/fs/overlayfs/util.c +++ b/fs/overlayfs/util.c @@ -15,6 +15,7 @@ #include <linux/uuid.h> #include <linux/namei.h> #include <linux/ratelimit.h> +#include <linux/overflow.h> #include "overlayfs.h" /* Get write access to upper mnt - may fail if upper sb was remounted ro */ @@ -145,9 +146,9 @@ void ovl_stack_free(struct ovl_path *stack, unsigned int n) struct ovl_entry *ovl_alloc_entry(unsigned int numlower) { - size_t size = offsetof(struct ovl_entry, __lowerstack[numlower]); - struct ovl_entry *oe = kzalloc(size, GFP_KERNEL); + struct ovl_entry *oe; + oe = kzalloc(struct_size(oe, __lowerstack, numlower), GFP_KERNEL); if (oe) oe->__numlower = numlower; @@ -305,7 +306,9 @@ enum ovl_path_type ovl_path_realdata(struct dentry *dentry, struct path *path) struct dentry *ovl_dentry_upper(struct dentry *dentry) { - return ovl_upperdentry_dereference(OVL_I(d_inode(dentry))); + struct inode *inode = d_inode(dentry); + + return inode ? ovl_upperdentry_dereference(OVL_I(inode)) : NULL; } struct dentry *ovl_dentry_lower(struct dentry *dentry) |