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Kernel: Use real UID/GID when checking for file access

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This aligns the rest of the system with POSIX, who says that access(2)
must check against the real UID and GID, not effective ones.
This commit is contained in:
sin-ack 2022-10-01 12:03:46 +00:00 • committed by Andrew Kaster
parent 3472c84d14
commit fa692e13f9
Notes: sideshowbarker 2024-07-17 23:00:03 +09:00
3 changed files with 20 additions and 12 deletions
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15
Kernel/FileSystem/InodeMetadata.cpp
View file

@ -9,19 +9,22 @@
namespace Kernel {
bool InodeMetadata::may_read(Credentials const& credentials) const
bool InodeMetadata::may_read(Credentials const& credentials, UseEffectiveIDs use_effective_ids) const
{
return may_read(credentials.euid(), credentials.egid(), credentials.extra_gids());
bool eids = use_effective_ids == UseEffectiveIDs::Yes;
return may_read(eids ? credentials.euid() : credentials.uid(), eids ? credentials.egid() : credentials.gid(), credentials.extra_gids());
}
bool InodeMetadata::may_write(Credentials const& credentials) const
bool InodeMetadata::may_write(Credentials const& credentials, UseEffectiveIDs use_effective_ids) const
{
return may_write(credentials.euid(), credentials.egid(), credentials.extra_gids());
bool eids = use_effective_ids == UseEffectiveIDs::Yes;
return may_write(eids ? credentials.euid() : credentials.uid(), eids ? credentials.egid() : credentials.gid(), credentials.extra_gids());
}
bool InodeMetadata::may_execute(Credentials const& credentials) const
bool InodeMetadata::may_execute(Credentials const& credentials, UseEffectiveIDs use_effective_ids) const
{
return may_execute(credentials.euid(), credentials.egid(), credentials.extra_gids());
bool eids = use_effective_ids == UseEffectiveIDs::Yes;
return may_execute(eids ? credentials.euid() : credentials.uid(), eids ? credentials.egid() : credentials.gid(), credentials.extra_gids());
}
}

11
Kernel/FileSystem/InodeMetadata.h
View file

@ -36,12 +36,17 @@ inline bool is_sticky(mode_t mode) { return (mode & S_ISVTX) == S_ISVTX; }
inline bool is_setuid(mode_t mode) { return (mode & S_ISUID) == S_ISUID; }
inline bool is_setgid(mode_t mode) { return (mode & S_ISGID) == S_ISGID; }
enum class UseEffectiveIDs {
Yes,
No
};
struct InodeMetadata {
bool is_valid() const { return inode.is_valid(); }
bool may_read(Credentials const&) const;
bool may_write(Credentials const&) const;
bool may_execute(Credentials const&) const;
bool may_read(Credentials const&, UseEffectiveIDs = UseEffectiveIDs::Yes) const;
bool may_write(Credentials const&, UseEffectiveIDs = UseEffectiveIDs::Yes) const;
bool may_execute(Credentials const&, UseEffectiveIDs = UseEffectiveIDs::Yes) const;
bool may_read(UserID u, GroupID g, Span<GroupID const> eg) const
{

6
Kernel/FileSystem/VirtualFileSystem.cpp
View file

@ -530,17 +530,17 @@ ErrorOr<void> VirtualFileSystem::access(Credentials const& credentials, StringVi
auto& inode = custody->inode();
auto metadata = inode.metadata();
if (mode & R_OK) {
if (!metadata.may_read(credentials))
if (!metadata.may_read(credentials, UseEffectiveIDs::No))
return EACCES;
}
if (mode & W_OK) {
if (!metadata.may_write(credentials))
if (!metadata.may_write(credentials, UseEffectiveIDs::No))
return EACCES;
if (custody->is_readonly())
return EROFS;
}
if (mode & X_OK) {
if (!metadata.may_execute(credentials))
if (!metadata.may_execute(credentials, UseEffectiveIDs::No))
return EACCES;
}
return {};