From 034dd340b08be1f2f0477ad16131d609f9dbd53c Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 30 Aug 2026 09:22:00 -0700 Subject: Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull tracing fixes from Steven Rostedt: - Fix error output of boot instance creation failure Currently if a boot instance creation fails, instead of printing out the name of the instance that failed, it prints "(null)". That is because it prints "cur_str" that had already been processed by strsep(). Print the saved name instead. While at it, print the error code of the failure. - Fix use-after-free for same named historgrams Histograms can be named so that they can be used in multiple events. But if the named histogram has a variable attached, the second event that uses the named histogram which duplicates it and needs to free the original after duplication leaves the old variable in place and still visible. If another histogram uses than variable, it will use the stale one which will try to reference the freed duplicate histogram and crash the kernel. Free the duplicate variables along with the duplicated histogram data. - Check return value of kthread_run() in event self test The events self tests uses a kthread for testing but does not check if it succeeded in creating a kthread. If the kthread creation were to fail, the code will still try to call kthread_stop() on the error returned. - Fix race between reading trace_pipe and updating subbuffer size If a user is reading the trace_pipe file at the same time they update the ring buffer sub-buffer size, can cause the trace_pipe read to read stale data. Add trace_access_lock() around updating the ring buffer sub-buffer size. - Fix eventfs_inode on failure path in creation of the events directory In the creation of the "events" directory, if after allocating the eventfs_inode a failure is detected, it calls cleanup_ei() which calls free_ei(). The free_ei() will test if eventfs_inode being freed has no children. It is a bug if it does. But on the failure case of the creation of the "events" directory, the children lists have not yet been initialized and the free will trigger a warning because list_empty() on an uninitialized list returns false. Move the initialization into init_ei() where it makes more sense and makes sure that a created eventfs_inode has its lists initialized upon creation. - Check return value of kthread_run() in ftrace direct sample code The sample code that shows how to use the ftrace direct calls does not test the return of kthread_run() to see if it succeeds. Return a failure if the kthread_run() doesn't succeed. - Clear user events state on fork in case of alloc failure On fork, the child gets a pointer to the parent's user events state. It makes a copy of it then updates the child's pointer to it. But if the allocation fails, the duplication function leaves the child with a pointer to its parent's descriptor. When the child cleans up its data, it will free the parent's descriptor while the parent is still using it. In the duplication function, set the child's user_event_mm to NULL before testing if the allocation succeeded, and when it exits it will not free the parent's descriptor. - Fix retry exhaustion in simple ring buffer reader swap simple_ring_buffer_swap_reader_page() starts with retry set to 8 and post-decrements it only after a failed link replacement. On the final attempt, a successful replacement leaves retry at zero, while a failed replacement leaves it at -1. But the check for success expects the retry value to be non-zero and exits with an error on zero. This is the opposite result. Fix it. - Fail nicely when the remote swap_reader_page() returns an error Currently, if the swap_reader_page() of a remote buffer fails, it triggers a WARN_ON_ONCE() and continues normally. Instead, have it exit with an error and a pr_warn() print instead of a full WARNING. * tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: ring-buffer: Stop remote reader update when page swap fails tracing: Fix retry exhaustion in simple ring buffer reader swap tracing/user_events: Clear copied tracing state before fork duplication samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify eventfs: Initialize ei->children and ei->list in init_ei() tracing: Fix use-after-free in trace_pipe read on sub-buffer order change tracing: Fix crash passing ERR_PTR to kthread_stop() tracing: Fix use-after-free with same-name named triggers tracing: Fix logged instance name on creation failure --- fs/afs/dynroot.c | 406 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 406 insertions(+) create mode 100644 fs/afs/dynroot.c (limited to 'fs/afs/dynroot.c') diff --git a/fs/afs/dynroot.c b/fs/afs/dynroot.c new file mode 100644 index 000000000..6e3c8c691 --- /dev/null +++ b/fs/afs/dynroot.c @@ -0,0 +1,406 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* AFS dynamic root handling + * + * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include +#include +#include +#include "internal.h" + +#define AFS_MIN_DYNROOT_CELL_INO 4 /* Allow for ., .., @cell, .@cell */ +#define AFS_MAX_DYNROOT_CELL_INO ((unsigned int)INT_MAX) + +static struct dentry *afs_lookup_atcell(struct inode *dir, struct dentry *dentry, ino_t ino); + +/* + * iget5() comparator for inode created by autocell operations + */ +static int afs_iget5_pseudo_test(struct inode *inode, void *opaque) +{ + struct afs_fid *fid = opaque; + + return inode->i_ino == fid->vnode; +} + +/* + * iget5() inode initialiser + */ +static int afs_iget5_pseudo_set(struct inode *inode, void *opaque) +{ + struct afs_super_info *as = AFS_FS_S(inode->i_sb); + struct afs_vnode *vnode = AFS_FS_I(inode); + struct afs_fid *fid = opaque; + + vnode->volume = as->volume; + vnode->fid = *fid; + inode->i_ino = fid->vnode; + inode->i_generation = fid->unique; + return 0; +} + +/* + * Create an inode for an autocell dynamic automount dir. + */ +static struct inode *afs_iget_pseudo_dir(struct super_block *sb, ino_t ino) +{ + struct afs_vnode *vnode; + struct inode *inode; + struct afs_fid fid = { .vnode = ino, .unique = 1, }; + + _enter(""); + + inode = iget5_locked(sb, fid.vnode, + afs_iget5_pseudo_test, afs_iget5_pseudo_set, &fid); + if (!inode) { + _leave(" = -ENOMEM"); + return ERR_PTR(-ENOMEM); + } + + _debug("GOT INODE %p { ino=%llu, vl=%llx, vn=%llx, u=%x }", + inode, inode->i_ino, fid.vid, fid.vnode, fid.unique); + + vnode = AFS_FS_I(inode); + + if (inode_state_read_once(inode) & I_NEW) { + netfs_inode_init(&vnode->netfs, NULL, false); + simple_inode_init_ts(inode); + set_nlink(inode, 2); + inode->i_size = 0; + inode->i_mode = S_IFDIR | 0555; + inode->i_op = &afs_autocell_inode_operations; + inode->i_uid = GLOBAL_ROOT_UID; + inode->i_gid = GLOBAL_ROOT_GID; + inode->i_blocks = 0; + inode->i_generation = 0; + inode->i_flags |= S_AUTOMOUNT | S_NOATIME; + + set_bit(AFS_VNODE_PSEUDODIR, &vnode->flags); + set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags); + + unlock_new_inode(inode); + } + _leave(" = %p", inode); + return inode; +} + +/* + * Try to automount the mountpoint with pseudo directory, if the autocell + * option is set. + */ +static struct dentry *afs_dynroot_lookup_cell(struct inode *dir, struct dentry *dentry, + unsigned int flags) +{ + struct afs_cell *cell = NULL; + struct afs_net *net = afs_d2net(dentry); + struct inode *inode = NULL; + const char *name = dentry->d_name.name; + size_t len = dentry->d_name.len; + bool dotted = false; + int ret = -ENOENT; + + /* Names prefixed with a dot are R/W mounts. */ + if (name[0] == '.') { + name++; + len--; + dotted = true; + } + + cell = afs_lookup_cell(net, name, len, NULL, + AFS_LOOKUP_CELL_DYNROOT, + afs_cell_trace_use_lookup_dynroot); + if (IS_ERR(cell)) { + ret = PTR_ERR(cell); + goto out_no_cell; + } + + inode = afs_iget_pseudo_dir(dir->i_sb, cell->dynroot_ino * 2 + dotted); + if (IS_ERR(inode)) { + ret = PTR_ERR(inode); + goto out; + } + + dentry->d_fsdata = cell; + return d_splice_alias(inode, dentry); + +out: + afs_unuse_cell(cell, afs_cell_trace_unuse_lookup_dynroot); +out_no_cell: + if (!inode) + return d_splice_alias(inode, dentry); + return ret == -ENOENT ? NULL : ERR_PTR(ret); +} + +/* + * Look up an entry in a dynroot directory. + */ +static struct dentry *afs_dynroot_lookup(struct inode *dir, struct dentry *dentry, + unsigned int flags) +{ + _enter("%pd", dentry); + + if (flags & LOOKUP_CREATE) + return ERR_PTR(-EOPNOTSUPP); + + if (dentry->d_name.len >= AFSNAMEMAX) { + _leave(" = -ENAMETOOLONG"); + return ERR_PTR(-ENAMETOOLONG); + } + + if (dentry->d_name.len == 5 && + memcmp(dentry->d_name.name, "@cell", 5) == 0) + return afs_lookup_atcell(dir, dentry, 2); + + if (dentry->d_name.len == 6 && + memcmp(dentry->d_name.name, ".@cell", 6) == 0) + return afs_lookup_atcell(dir, dentry, 3); + + return afs_dynroot_lookup_cell(dir, dentry, flags); +} + +const struct inode_operations afs_dynroot_inode_operations = { + .lookup = afs_dynroot_lookup, +}; + +static void afs_dynroot_d_release(struct dentry *dentry) +{ + struct afs_cell *cell = dentry->d_fsdata; + + afs_unuse_cell(cell, afs_cell_trace_unuse_dynroot_mntpt); +} + +/* + * Keep @cell symlink dentries around, but only keep cell autodirs when they're + * being used. + */ +static int afs_dynroot_delete_dentry(const struct dentry *dentry) +{ + const struct qstr *name = &dentry->d_name; + + if (name->len == 5 && memcmp(name->name, "@cell", 5) == 0) + return 0; + if (name->len == 6 && memcmp(name->name, ".@cell", 6) == 0) + return 0; + return 1; +} + +const struct dentry_operations afs_dynroot_dentry_operations = { + .d_delete = afs_dynroot_delete_dentry, + .d_release = afs_dynroot_d_release, + .d_automount = afs_d_automount, +}; + +static void afs_atcell_delayed_put_cell(void *arg) +{ + struct afs_cell *cell = arg; + + afs_put_cell(cell, afs_cell_trace_put_atcell); +} + +/* + * Read @cell or .@cell symlinks. + */ +static const char *afs_atcell_get_link(struct dentry *dentry, struct inode *inode, + struct delayed_call *done) +{ + struct afs_vnode *vnode = AFS_FS_I(inode); + struct afs_cell *cell; + struct afs_net *net = afs_i2net(inode); + const char *name; + bool dotted = vnode->fid.vnode == 3; + + if (!rcu_access_pointer(net->ws_cell)) + return ERR_PTR(-ENOENT); + + if (!dentry) { + /* We're in RCU-pathwalk. */ + cell = rcu_dereference(net->ws_cell); + if (dotted) + name = cell->name - 1; + else + name = cell->name; + /* Shouldn't need to set a delayed call. */ + return name; + } + + down_read(&net->cells_lock); + + cell = rcu_dereference_protected(net->ws_cell, lockdep_is_held(&net->cells_lock)); + if (dotted) + name = cell->name - 1; + else + name = cell->name; + afs_get_cell(cell, afs_cell_trace_get_atcell); + set_delayed_call(done, afs_atcell_delayed_put_cell, cell); + + up_read(&net->cells_lock); + return name; +} + +static const struct inode_operations afs_atcell_inode_operations = { + .get_link = afs_atcell_get_link, +}; + +/* + * Create an inode for the @cell or .@cell symlinks. + */ +static struct dentry *afs_lookup_atcell(struct inode *dir, struct dentry *dentry, ino_t ino) +{ + struct afs_vnode *vnode; + struct inode *inode; + struct afs_fid fid = { .vnode = ino, .unique = 1, }; + + inode = iget5_locked(dir->i_sb, fid.vnode, + afs_iget5_pseudo_test, afs_iget5_pseudo_set, &fid); + if (!inode) + return ERR_PTR(-ENOMEM); + + vnode = AFS_FS_I(inode); + + if (inode_state_read_once(inode) & I_NEW) { + netfs_inode_init(&vnode->netfs, NULL, false); + simple_inode_init_ts(inode); + set_nlink(inode, 1); + inode->i_size = 0; + inode->i_mode = S_IFLNK | 0555; + inode->i_op = &afs_atcell_inode_operations; + inode->i_uid = GLOBAL_ROOT_UID; + inode->i_gid = GLOBAL_ROOT_GID; + inode->i_blocks = 0; + inode->i_generation = 0; + inode->i_flags |= S_NOATIME; + + unlock_new_inode(inode); + } + return d_splice_alias(inode, dentry); +} + +/* + * Transcribe the cell database into readdir content under net->cells_lock. + * Each cell produces two entries, one prefixed with a dot and one not. + */ +static int afs_dynroot_readdir_cells(struct afs_net *net, struct dir_context *ctx) +{ + const struct afs_cell *cell; + loff_t newpos; + + _enter("%llu", ctx->pos); + + for (;;) { + unsigned int ix = ctx->pos >> 1; + + cell = idr_get_next(&net->cells_dyn_ino, &ix); + if (!cell) + return 0; + if (READ_ONCE(cell->state) == AFS_CELL_REMOVING || + READ_ONCE(cell->state) == AFS_CELL_DEAD) { + ctx->pos += 2; + ctx->pos &= ~1; + continue; + } + + newpos = ix << 1; + if (newpos > ctx->pos) + ctx->pos = newpos; + + _debug("pos %llu -> cell %u", ctx->pos, cell->dynroot_ino); + + if ((ctx->pos & 1) == 0) { + if (!dir_emit(ctx, cell->name, cell->name_len, + cell->dynroot_ino, DT_DIR)) + return 0; + ctx->pos++; + } + if ((ctx->pos & 1) == 1) { + if (!dir_emit(ctx, cell->name - 1, cell->name_len + 1, + cell->dynroot_ino + 1, DT_DIR)) + return 0; + ctx->pos++; + } + } + return 0; +} + +/* + * Read the AFS dynamic root directory. This produces a list of cellnames, + * dotted and undotted, along with @cell and .@cell links if configured. + */ +static int afs_dynroot_readdir(struct file *file, struct dir_context *ctx) +{ + struct afs_net *net = afs_d2net(file->f_path.dentry); + int ret = 0; + + if (!dir_emit_dots(file, ctx)) + return 0; + + if (ctx->pos == 2) { + if (rcu_access_pointer(net->ws_cell) && + !dir_emit(ctx, "@cell", 5, 2, DT_LNK)) + return 0; + ctx->pos = 3; + } + if (ctx->pos == 3) { + if (rcu_access_pointer(net->ws_cell) && + !dir_emit(ctx, ".@cell", 6, 3, DT_LNK)) + return 0; + ctx->pos = 4; + } + + if ((unsigned long long)ctx->pos <= AFS_MAX_DYNROOT_CELL_INO) { + down_read(&net->cells_lock); + ret = afs_dynroot_readdir_cells(net, ctx); + up_read(&net->cells_lock); + } + return ret; +} + +static const struct file_operations afs_dynroot_file_operations = { + .llseek = generic_file_llseek, + .read = generic_read_dir, + .iterate_shared = afs_dynroot_readdir, + .fsync = noop_fsync, +}; + +/* + * Create an inode for a dynamic root directory. + */ +struct inode *afs_dynroot_iget_root(struct super_block *sb) +{ + struct afs_super_info *as = AFS_FS_S(sb); + struct afs_vnode *vnode; + struct inode *inode; + struct afs_fid fid = { .vid = 0, .vnode = 1, .unique = 1,}; + + if (as->volume) + fid.vid = as->volume->vid; + + inode = iget5_locked(sb, fid.vnode, + afs_iget5_pseudo_test, afs_iget5_pseudo_set, &fid); + if (!inode) + return ERR_PTR(-ENOMEM); + + vnode = AFS_FS_I(inode); + + /* there shouldn't be an existing inode */ + if (inode_state_read_once(inode) & I_NEW) { + netfs_inode_init(&vnode->netfs, NULL, false); + simple_inode_init_ts(inode); + set_nlink(inode, 2); + inode->i_size = 0; + inode->i_mode = S_IFDIR | 0555; + inode->i_op = &afs_dynroot_inode_operations; + inode->i_fop = &afs_dynroot_file_operations; + inode->i_uid = GLOBAL_ROOT_UID; + inode->i_gid = GLOBAL_ROOT_GID; + inode->i_blocks = 0; + inode->i_generation = 0; + inode->i_flags |= S_NOATIME; + + set_bit(AFS_VNODE_PSEUDODIR, &vnode->flags); + unlock_new_inode(inode); + } + _leave(" = %p", inode); + return inode; +} -- cgit v1.3.1