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Kernel: Make Inode::lookup() return a RefPtr<Inode>

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Previously this API would return an InodeIdentifier, which meant that
there was a race in path resolution where an inode could be unlinked
in between finding the InodeIdentifier for a path component, and
actually resolving that to an Inode object.

Attaching a test that would quickly trip an assertion before.

Test: Kernel/path-resolution-race.cpp
This commit is contained in:
Andreas Kling 2020-02-01 09:23:46 +01:00
parent 5aa37f6f5c
commit c44b4d61f3
11 changed files with 50 additions and 36 deletions
Download patch file Download diff file Expand all files Collapse all files

28
Kernel/FileSystem/ProcFS.cpp
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@ -1298,13 +1298,13 @@ bool ProcFSInode::traverse_as_directory(Function<bool(const FS::DirectoryEntry&)
return true;
}
InodeIdentifier ProcFSInode::lookup(StringView name)
RefPtr<Inode> ProcFSInode::lookup(StringView name)
{
ASSERT(is_directory());
if (name == ".")
return identifier();
return fs().get_inode(identifier());
if (name == "..")
return to_parent_id(identifier());
return fs().get_inode(to_parent_id(identifier()));
auto proc_file_type = to_proc_file_type(identifier());
@ -1314,7 +1314,7 @@ InodeIdentifier ProcFSInode::lookup(StringView name)
continue;
if (entry.proc_file_type > __FI_Root_Start && entry.proc_file_type < __FI_Root_End) {
if (name == entry.name) {
return to_identifier(fsid(), PDI_Root, 0, (ProcFileType)entry.proc_file_type);
return fs().get_inode(to_identifier(fsid(), PDI_Root, 0, (ProcFileType)entry.proc_file_type));
}
}
}
@ -1327,7 +1327,7 @@ InodeIdentifier ProcFSInode::lookup(StringView name)
process_exists = Process::from_pid(name_as_number);
}
if (process_exists)
return to_identifier(fsid(), PDI_Root, name_as_number, FI_PID);
return fs().get_inode(to_identifier(fsid(), PDI_Root, name_as_number, FI_PID));
}
return {};
}
@ -1336,22 +1336,22 @@ InodeIdentifier ProcFSInode::lookup(StringView name)
for (int i = 1; i < sys_variables().size(); ++i) {
auto& variable = sys_variables()[i];
if (name == variable.name)
return sys_var_to_identifier(fsid(), i);
return fs().get_inode(sys_var_to_identifier(fsid(), i));
}
return {};
}
if (proc_file_type == FI_Root_net) {
if (name == "adapters")
return to_identifier(fsid(), PDI_Root, 0, FI_Root_net_adapters);
return fs().get_inode(to_identifier(fsid(), PDI_Root, 0, FI_Root_net_adapters));
if (name == "arp")
return to_identifier(fsid(), PDI_Root, 0, FI_Root_net_arp);
return fs().get_inode(to_identifier(fsid(), PDI_Root, 0, FI_Root_net_arp));
if (name == "tcp")
return to_identifier(fsid(), PDI_Root, 0, FI_Root_net_tcp);
return fs().get_inode(to_identifier(fsid(), PDI_Root, 0, FI_Root_net_tcp));
if (name == "udp")
return to_identifier(fsid(), PDI_Root, 0, FI_Root_net_udp);
return fs().get_inode(to_identifier(fsid(), PDI_Root, 0, FI_Root_net_udp));
if (name == "local")
return to_identifier(fsid(), PDI_Root, 0, FI_Root_net_local);
return fs().get_inode(to_identifier(fsid(), PDI_Root, 0, FI_Root_net_local));
return {};
}
@ -1367,7 +1367,7 @@ InodeIdentifier ProcFSInode::lookup(StringView name)
if (entry.name == nullptr)
continue;
if (name == entry.name) {
return to_identifier(fsid(), PDI_PID, to_pid(identifier()), (ProcFileType)entry.proc_file_type);
return fs().get_inode(to_identifier(fsid(), PDI_PID, to_pid(identifier()), (ProcFileType)entry.proc_file_type));
}
}
}
@ -1385,7 +1385,7 @@ InodeIdentifier ProcFSInode::lookup(StringView name)
fd_exists = process->file_description(name_as_number);
}
if (fd_exists)
return to_identifier_with_fd(fsid(), to_pid(identifier()), name_as_number);
return fs().get_inode(to_identifier_with_fd(fsid(), to_pid(identifier()), name_as_number));
}
}
return {};
@ -1529,7 +1529,7 @@ KResult ProcFSProxyInode::remove_child(const StringView& name)
return m_fd->inode()->remove_child(name);
}
InodeIdentifier ProcFSProxyInode::lookup(StringView name)
RefPtr<Inode> ProcFSProxyInode::lookup(StringView name)
{
if (!m_fd->inode())
return {};