diff options
Diffstat (limited to 'fs/namei.c')
| -rw-r--r-- | fs/namei.c | 117 |
1 files changed, 77 insertions, 40 deletions
diff --git a/fs/namei.c b/fs/namei.c index 509657fdf4f5..1f28d3f463c3 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -22,6 +22,7 @@ #include <linux/fs.h> #include <linux/namei.h> #include <linux/pagemap.h> +#include <linux/sched/mm.h> #include <linux/fsnotify.h> #include <linux/personality.h> #include <linux/security.h> @@ -729,13 +730,6 @@ static bool legitimize_links(struct nameidata *nd) static bool legitimize_root(struct nameidata *nd) { - /* - * For scoped-lookups (where nd->root has been zeroed), we need to - * restart the whole lookup from scratch -- because set_root() is wrong - * for these lookups (nd->dfd is the root, not the filesystem root). - */ - if (!nd->root.mnt && (nd->flags & LOOKUP_IS_SCOPED)) - return false; /* Nothing to do if nd->root is zero or is managed by the VFS user. */ if (!nd->root.mnt || (nd->state & ND_ROOT_PRESET)) return true; @@ -797,7 +791,7 @@ out: * @seq: seq number to check @dentry against * Returns: true on success, false on failure * - * Similar to to try_to_unlazy(), but here we have the next dentry already + * Similar to try_to_unlazy(), but here we have the next dentry already * picked by rcu-walk and want to legitimize that in addition to the current * nd->path and nd->root for ref-walk mode. Must be called from rcu-walk context. * Nothing should touch nameidata between try_to_unlazy_next() failure and @@ -1031,7 +1025,7 @@ static struct ctl_table namei_sysctls[] = { .procname = "protected_symlinks", .data = &sysctl_protected_symlinks, .maxlen = sizeof(int), - .mode = 0600, + .mode = 0644, .proc_handler = proc_dointvec_minmax, .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_ONE, @@ -1040,7 +1034,7 @@ static struct ctl_table namei_sysctls[] = { .procname = "protected_hardlinks", .data = &sysctl_protected_hardlinks, .maxlen = sizeof(int), - .mode = 0600, + .mode = 0644, .proc_handler = proc_dointvec_minmax, .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_ONE, @@ -1049,7 +1043,7 @@ static struct ctl_table namei_sysctls[] = { .procname = "protected_fifos", .data = &sysctl_protected_fifos, .maxlen = sizeof(int), - .mode = 0600, + .mode = 0644, .proc_handler = proc_dointvec_minmax, .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_TWO, @@ -1058,7 +1052,7 @@ static struct ctl_table namei_sysctls[] = { .procname = "protected_regular", .data = &sysctl_protected_regular, .maxlen = sizeof(int), - .mode = 0600, + .mode = 0644, .proc_handler = proc_dointvec_minmax, .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_TWO, @@ -1754,7 +1748,7 @@ static int reserve_stack(struct nameidata *nd, struct path *link, unsigned seq) // unlazy even if we fail to grab the link - cleanup needs it bool grabbed_link = legitimize_path(nd, link, seq); - if (!try_to_unlazy(nd) != 0 || !grabbed_link) + if (!try_to_unlazy(nd) || !grabbed_link) return -ECHILD; if (nd_alloc_stack(nd)) @@ -2768,7 +2762,8 @@ struct dentry *lookup_one(struct user_namespace *mnt_userns, const char *name, EXPORT_SYMBOL(lookup_one); /** - * lookup_one_len_unlocked - filesystem helper to lookup single pathname component + * lookup_one_unlocked - filesystem helper to lookup single pathname component + * @mnt_userns: idmapping of the mount the lookup is performed from * @name: pathname component to lookup * @base: base directory to lookup from * @len: maximum length @len should be interpreted to @@ -2779,14 +2774,15 @@ EXPORT_SYMBOL(lookup_one); * Unlike lookup_one_len, it should be called without the parent * i_mutex held, and will take the i_mutex itself if necessary. */ -struct dentry *lookup_one_len_unlocked(const char *name, - struct dentry *base, int len) +struct dentry *lookup_one_unlocked(struct user_namespace *mnt_userns, + const char *name, struct dentry *base, + int len) { struct qstr this; int err; struct dentry *ret; - err = lookup_one_common(&init_user_ns, name, base, len, &this); + err = lookup_one_common(mnt_userns, name, base, len, &this); if (err) return ERR_PTR(err); @@ -2795,6 +2791,59 @@ struct dentry *lookup_one_len_unlocked(const char *name, ret = lookup_slow(&this, base, 0); return ret; } +EXPORT_SYMBOL(lookup_one_unlocked); + +/** + * lookup_one_positive_unlocked - filesystem helper to lookup single + * pathname component + * @mnt_userns: idmapping of the mount the lookup is performed from + * @name: pathname component to lookup + * @base: base directory to lookup from + * @len: maximum length @len should be interpreted to + * + * This helper will yield ERR_PTR(-ENOENT) on negatives. The helper returns + * known positive or ERR_PTR(). This is what most of the users want. + * + * Note that pinned negative with unlocked parent _can_ become positive at any + * time, so callers of lookup_one_unlocked() need to be very careful; pinned + * positives have >d_inode stable, so this one avoids such problems. + * + * Note that this routine is purely a helper for filesystem usage and should + * not be called by generic code. + * + * The helper should be called without i_mutex held. + */ +struct dentry *lookup_one_positive_unlocked(struct user_namespace *mnt_userns, + const char *name, + struct dentry *base, int len) +{ + struct dentry *ret = lookup_one_unlocked(mnt_userns, name, base, len); + + if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { + dput(ret); + ret = ERR_PTR(-ENOENT); + } + return ret; +} +EXPORT_SYMBOL(lookup_one_positive_unlocked); + +/** + * lookup_one_len_unlocked - filesystem helper to lookup single pathname component + * @name: pathname component to lookup + * @base: base directory to lookup from + * @len: maximum length @len should be interpreted to + * + * Note that this routine is purely a helper for filesystem usage and should + * not be called by generic code. + * + * Unlike lookup_one_len, it should be called without the parent + * i_mutex held, and will take the i_mutex itself if necessary. + */ +struct dentry *lookup_one_len_unlocked(const char *name, + struct dentry *base, int len) +{ + return lookup_one_unlocked(&init_user_ns, name, base, len); +} EXPORT_SYMBOL(lookup_one_len_unlocked); /* @@ -2808,12 +2857,7 @@ EXPORT_SYMBOL(lookup_one_len_unlocked); struct dentry *lookup_positive_unlocked(const char *name, struct dentry *base, int len) { - struct dentry *ret = lookup_one_len_unlocked(name, base, len); - if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { - dput(ret); - ret = ERR_PTR(-ENOENT); - } - return ret; + return lookup_one_positive_unlocked(&init_user_ns, name, base, len); } EXPORT_SYMBOL(lookup_positive_unlocked); @@ -5001,28 +5045,28 @@ int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) } EXPORT_SYMBOL(page_readlink); -/* - * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS - */ -int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) +int page_symlink(struct inode *inode, const char *symname, int len) { struct address_space *mapping = inode->i_mapping; + const struct address_space_operations *aops = mapping->a_ops; + bool nofs = !mapping_gfp_constraint(mapping, __GFP_FS); struct page *page; void *fsdata; int err; - unsigned int flags = 0; - if (nofs) - flags |= AOP_FLAG_NOFS; + unsigned int flags; retry: - err = pagecache_write_begin(NULL, mapping, 0, len-1, - flags, &page, &fsdata); + if (nofs) + flags = memalloc_nofs_save(); + err = aops->write_begin(NULL, mapping, 0, len-1, &page, &fsdata); + if (nofs) + memalloc_nofs_restore(flags); if (err) goto fail; memcpy(page_address(page), symname, len-1); - err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, + err = aops->write_end(NULL, mapping, 0, len-1, len-1, page, fsdata); if (err < 0) goto fail; @@ -5034,13 +5078,6 @@ retry: fail: return err; } -EXPORT_SYMBOL(__page_symlink); - -int page_symlink(struct inode *inode, const char *symname, int len) -{ - return __page_symlink(inode, symname, len, - !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); -} EXPORT_SYMBOL(page_symlink); const struct inode_operations page_symlink_inode_operations = { |