cregit-Linux how code gets into the kernel

Release 4.18 fs/attr.c

Directory: fs
// SPDX-License-Identifier: GPL-2.0
 *  linux/fs/attr.c
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *  changes by Thomas Schoebel-Theuer

#include <linux/export.h>
#include <linux/time.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/sched/signal.h>
#include <linux/capability.h>
#include <linux/fsnotify.h>
#include <linux/fcntl.h>
#include <linux/security.h>
#include <linux/evm.h>
#include <linux/ima.h>

static bool chown_ok(const struct inode *inode, kuid_t uid) { if (uid_eq(current_fsuid(), inode->i_uid) && uid_eq(uid, inode->i_uid)) return true; if (capable_wrt_inode_uidgid(inode, CAP_CHOWN)) return true; if (uid_eq(inode->i_uid, INVALID_UID) && ns_capable(inode->i_sb->s_user_ns, CAP_CHOWN)) return true; return false; }


Eric W. Biedermann79100.00%1100.00%

static bool chgrp_ok(const struct inode *inode, kgid_t gid) { if (uid_eq(current_fsuid(), inode->i_uid) && (in_group_p(gid) || gid_eq(gid, inode->i_gid))) return true; if (capable_wrt_inode_uidgid(inode, CAP_CHOWN)) return true; if (gid_eq(inode->i_gid, INVALID_GID) && ns_capable(inode->i_sb->s_user_ns, CAP_CHOWN)) return true; return false; }


Eric W. Biedermann86100.00%1100.00%

/** * setattr_prepare - check if attribute changes to a dentry are allowed * @dentry: dentry to check * @attr: attributes to change * * Check if we are allowed to change the attributes contained in @attr * in the given dentry. This includes the normal unix access permission * checks, as well as checks for rlimits and others. The function also clears * SGID bit from mode if user is not allowed to set it. Also file capabilities * and IMA extended attributes are cleared if ATTR_KILL_PRIV is set. * * Should be called as the first thing in ->setattr implementations, * possibly after taking additional locks. */
int setattr_prepare(struct dentry *dentry, struct iattr *attr) { struct inode *inode = d_inode(dentry); unsigned int ia_valid = attr->ia_valid; /* * First check size constraints. These can't be overriden using * ATTR_FORCE. */ if (ia_valid & ATTR_SIZE) { int error = inode_newsize_ok(inode, attr->ia_size); if (error) return error; } /* If force is set do it anyway. */ if (ia_valid & ATTR_FORCE) goto kill_priv; /* Make sure a caller can chown. */ if ((ia_valid & ATTR_UID) && !chown_ok(inode, attr->ia_uid)) return -EPERM; /* Make sure caller can chgrp. */ if ((ia_valid & ATTR_GID) && !chgrp_ok(inode, attr->ia_gid)) return -EPERM; /* Make sure a caller can chmod. */ if (ia_valid & ATTR_MODE) { if (!inode_owner_or_capable(inode)) return -EPERM; /* Also check the setgid bit! */ if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid : inode->i_gid) && !capable_wrt_inode_uidgid(inode, CAP_FSETID)) attr->ia_mode &= ~S_ISGID; } /* Check for setting the inode time. */ if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) { if (!inode_owner_or_capable(inode)) return -EPERM; } kill_priv: /* User has permission for the change */ if (ia_valid & ATTR_KILL_PRIV) { int error; error = security_inode_killpriv(dentry); if (error) return error; } return 0; }


Linus Torvalds (pre-git)12553.88%426.67%
Christoph Hellwig4519.40%16.67%
Jan Kara4418.97%213.33%
Eric W. Biedermann104.31%320.00%
Miklos Szeredi20.86%16.67%
Satyam Sharma20.86%16.67%
Serge E. Hallyn20.86%16.67%
Andrew Lutomirski10.43%16.67%
Chris Wright10.43%16.67%

EXPORT_SYMBOL(setattr_prepare); /** * inode_newsize_ok - may this inode be truncated to a given size * @inode: the inode to be truncated * @offset: the new size to assign to the inode * @Returns: 0 on success, -ve errno on failure * * inode_newsize_ok must be called with i_mutex held. * * inode_newsize_ok will check filesystem limits and ulimits to check that the * new inode size is within limits. inode_newsize_ok will also send SIGXFSZ * when necessary. Caller must not proceed with inode size change if failure is * returned. @inode must be a file (not directory), with appropriate * permissions to allow truncate (inode_newsize_ok does NOT check these * conditions). */
int inode_newsize_ok(const struct inode *inode, loff_t offset) { if (inode->i_size < offset) { unsigned long limit; limit = rlimit(RLIMIT_FSIZE); if (limit != RLIM_INFINITY && offset > limit) goto out_sig; if (offset > inode->i_sb->s_maxbytes) goto out_big; } else { /* * truncation of in-use swapfiles is disallowed - it would * cause subsequent swapout to scribble on the now-freed * blocks. */ if (IS_SWAPFILE(inode)) return -ETXTBSY; } return 0; out_sig: send_sig(SIGXFSZ, current, 0); out_big: return -EFBIG; }


Nicholas Piggin9396.88%150.00%
Jiri Slaby33.12%150.00%

EXPORT_SYMBOL(inode_newsize_ok); /** * setattr_copy - copy simple metadata updates into the generic inode * @inode: the inode to be updated * @attr: the new attributes * * setattr_copy must be called with i_mutex held. * * setattr_copy updates the inode's metadata with that specified * in attr. Noticeably missing is inode size update, which is more complex * as it requires pagecache updates. * * The inode is not marked as dirty after this operation. The rationale is * that for "simple" filesystems, the struct inode is the inode storage. * The caller is free to mark the inode dirty afterwards if needed. */
void setattr_copy(struct inode *inode, const struct iattr *attr) { unsigned int ia_valid = attr->ia_valid; if (ia_valid & ATTR_UID) inode->i_uid = attr->ia_uid; if (ia_valid & ATTR_GID) inode->i_gid = attr->ia_gid; if (ia_valid & ATTR_ATIME) inode->i_atime = timespec64_trunc(attr->ia_atime, inode->i_sb->s_time_gran); if (ia_valid & ATTR_MTIME) inode->i_mtime = timespec64_trunc(attr->ia_mtime, inode->i_sb->s_time_gran); if (ia_valid & ATTR_CTIME) inode->i_ctime = timespec64_trunc(attr->ia_ctime, inode->i_sb->s_time_gran); if (ia_valid & ATTR_MODE) { umode_t mode = attr->ia_mode; if (!in_group_p(inode->i_gid) && !capable_wrt_inode_uidgid(inode, CAP_FSETID)) mode &= ~S_ISGID; inode->i_mode = mode; } }


Linus Torvalds (pre-git)11267.88%538.46%
Andi Kleen2414.55%17.69%
Andrew Morton116.67%17.69%
Linus Torvalds84.85%17.69%
Nicholas Piggin31.82%17.69%
Deepa Dinamani31.82%17.69%
Eric W. Biedermann21.21%17.69%
Andrew Lutomirski10.61%17.69%
Christoph Hellwig10.61%17.69%

EXPORT_SYMBOL(setattr_copy); /** * notify_change - modify attributes of a filesytem object * @dentry: object affected * @iattr: new attributes * @delegated_inode: returns inode, if the inode is delegated * * The caller must hold the i_mutex on the affected object. * * If notify_change discovers a delegation in need of breaking, * it will return -EWOULDBLOCK and return a reference to the inode in * delegated_inode. The caller should then break the delegation and * retry. Because breaking a delegation may take a long time, the * caller should drop the i_mutex before doing so. * * Alternatively, a caller may pass NULL for delegated_inode. This may * be appropriate for callers that expect the underlying filesystem not * to be NFS exported. Also, passing NULL is fine for callers holding * the file open for write, as there can be no conflicting delegation in * that case. */
int notify_change(struct dentry * dentry, struct iattr * attr, struct inode **delegated_inode) { struct inode *inode = dentry->d_inode; umode_t mode = inode->i_mode; int error; struct timespec64 now; unsigned int ia_valid = attr->ia_valid; WARN_ON_ONCE(!inode_is_locked(inode)); if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) { if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) return -EPERM; } /* * If utimes(2) and friends are called with times == NULL (or both * times are UTIME_NOW), then we need to check for write permission */ if (ia_valid & ATTR_TOUCH) { if (IS_IMMUTABLE(inode)) return -EPERM; if (!inode_owner_or_capable(inode)) { error = inode_permission(inode, MAY_WRITE); if (error) return error; } } if ((ia_valid & ATTR_MODE)) { umode_t amode = attr->ia_mode; /* Flag setting protected by i_mutex */ if (is_sxid(amode)) inode->i_flags &= ~S_NOSEC; } now = current_time(inode); attr->ia_ctime = now; if (!(ia_valid & ATTR_ATIME_SET)) attr->ia_atime = now; if (!(ia_valid & ATTR_MTIME_SET)) attr->ia_mtime = now; if (ia_valid & ATTR_KILL_PRIV) { error = security_inode_need_killpriv(dentry); if (error < 0) return error; if (error == 0) ia_valid = attr->ia_valid &= ~ATTR_KILL_PRIV; } /* * We now pass ATTR_KILL_S*ID to the lower level setattr function so * that the function has the ability to reinterpret a mode change * that's due to these bits. This adds an implicit restriction that * no function will ever call notify_change with both ATTR_MODE and * ATTR_KILL_S*ID set. */ if ((ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) && (ia_valid & ATTR_MODE)) BUG(); if (ia_valid & ATTR_KILL_SUID) { if (mode & S_ISUID) { ia_valid = attr->ia_valid |= ATTR_MODE; attr->ia_mode = (inode->i_mode & ~S_ISUID); } } if (ia_valid & ATTR_KILL_SGID) { if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { if (!(ia_valid & ATTR_MODE)) { ia_valid = attr->ia_valid |= ATTR_MODE; attr->ia_mode = inode->i_mode; } attr->ia_mode &= ~S_ISGID; } } if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID))) return 0; /* * Verify that uid/gid changes are valid in the target * namespace of the superblock. */ if (ia_valid & ATTR_UID && !kuid_has_mapping(inode->i_sb->s_user_ns, attr->ia_uid)) return -EOVERFLOW; if (ia_valid & ATTR_GID && !kgid_has_mapping(inode->i_sb->s_user_ns, attr->ia_gid)) return -EOVERFLOW; /* Don't allow modifications of files with invalid uids or * gids unless those uids & gids are being made valid. */ if (!(ia_valid & ATTR_UID) && !uid_valid(inode->i_uid)) return -EOVERFLOW; if (!(ia_valid & ATTR_GID) && !gid_valid(inode->i_gid)) return -EOVERFLOW; error = security_inode_setattr(dentry, attr); if (error) return error; error = try_break_deleg(inode, delegated_inode); if (error) return error; if (inode->i_op->setattr) error = inode->i_op->setattr(dentry, attr); else error = simple_setattr(dentry, attr); if (!error) { fsnotify_change(dentry, ia_valid); ima_inode_post_setattr(dentry); evm_inode_post_setattr(dentry, ia_valid); } return error; }


Linus Torvalds (pre-git)11319.58%618.75%
Al Viro9917.16%412.50%
Miklos Szeredi9416.29%39.38%
Seth Forshee498.49%13.12%
Eric W. Biedermann437.45%13.12%
Jeff Layton356.07%13.12%
Andi Kleen325.55%26.25%
Serge E. Hallyn254.33%13.12%
J. Bruce Fields223.81%13.12%
Jan Kara142.43%13.12%
Mimi Zohar142.43%26.25%
Chuck Lever122.08%13.12%
Andrew Morton81.39%13.12%
Adrian Bunk61.04%13.12%
Dave Hansen30.52%13.12%
Robert Love20.35%13.12%
Deepa Dinamani20.35%26.25%
Stephen D. Smalley20.35%13.12%
Christoph Hellwig20.35%13.12%


Overall Contributors

Linus Torvalds (pre-git)36428.13%1016.39%
Eric W. Biedermann22017.00%46.56%
Nicholas Piggin1068.19%23.28%
Al Viro997.65%46.56%
Miklos Szeredi967.42%46.56%
Jan Kara604.64%23.28%
Andi Kleen564.33%34.92%
Christoph Hellwig493.79%34.92%
Seth Forshee493.79%11.64%
Jeff Layton352.70%11.64%
Serge E. Hallyn272.09%23.28%
J. Bruce Fields231.78%11.64%
Mimi Zohar201.55%23.28%
Andrew Morton191.47%23.28%
Chuck Lever120.93%11.64%
Arnaldo Carvalho de Melo110.85%11.64%
Linus Torvalds100.77%23.28%
Adrian Bunk60.46%11.64%
Deepa Dinamani50.39%23.28%
Ingo Molnar30.23%11.64%
Jiri Slaby30.23%11.64%
Randy Dunlap30.23%11.64%
Robert Love30.23%11.64%
Stephen D. Smalley30.23%11.64%
Dave Hansen30.23%11.64%
Satyam Sharma20.15%11.64%
Andrew Lutomirski20.15%11.64%
Chris Wright10.08%11.64%
Paul Gortmaker10.08%11.64%
Greg Kroah-Hartman10.08%11.64%
Dave Jones10.08%11.64%
Lucas De Marchi10.08%11.64%
Directory: fs
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